Seismic Stratigraphy Shallow Waters 2013
Transcript of Seismic Stratigraphy Shallow Waters 2013
New insights into seismic stratigraphy of shallow-waterprogradational sequences Subseismic clinoforms
Hongliu Zeng1 Xiaomin Zhu2 and Rukai Zhu3
Abstract
Seismic clinoforms are the key building blocks for constructing the seismic stratigraphy of progradationaldepositional sequences However not all progradational systems are necessarily represented by seismic clino-forms We evaluated the definition and interpretation of progradational systems that do not associate with seis-mic clinoforms Nonclinoform (or subseismic clinoforms) seismic facies are mainly related to shallow-waterdeltas where the thickness of a prograding clinoform complex is too thin to be imaged as an offlapping reflectionconfiguration The clinoform detection limit for clinoform imaging is defined as one wavelength (the thicknessof two seismic events) and is related to the predominant frequency of the seismic data and the velocity ofthe sediments Three examples from the Songliao Basin of China and Gulf of Mexico illustrated ancientshallow-water deltas with various morphologies in lacustrine and marine environments by integrating the analy-sis of the core wireline logs and amplitude stratal slices made from nonclinoform seismic events A seismicmodel of an outcrop carbonate clinoform complex in west Texas further demonstrated the seismic frequencycontrol on clinoform seismic stratigraphy including transitions between different types of clinoforms andbetween clinoforms and nonclinoform seismic facies Ambiguity in interpreting nonclinoform seismicfacies can be reduced by high-resolution acquisition high-frequency enhancement processing and seismicsedimentology
IntroductionThe term clinoform is proposed by Rich (1951) to
depict the shape of a depositional surface at the scaleof the entire continental margin (Figure 1) A clinoformresults from the varying rate of deposition and waterdepth its upper end connecting to a flat shallow-water undaform and its lower end graduating into ahorizontal deep-water fondoform Multiple clinoformaldepositional units compose a unique easy-to-recognizestratigraphic pattern in the continental margin
Mitchum et al (1977) adapt the term and use it tocharacterize a group of very special seismic reflectionsthat are typically composed of topset foreset and bot-tomset (roughly corresponding to undaform clinoformand fondoform of Rich [1951] respectively) A clino-form was interpreted as strata in which significant dep-osition is produced by lateral outbuilding or basinwardprograding forming the gently sloping depositional sur-faces (clinoforms) Although seismic clinoforms can re-sult from any prograding depositional process they aregenerally produced by deltas that prograded seaward
(Sangree and Widmier 1977) Berg (1982) further estab-lishes a relationship between some different deltaicfacies and distinctive clinoform seismic facies Seismicclinoform patterns are also common in ramp bankand platform carbonate depositional systems (egBelopolsky and Droxler 2004 Droste and Steenwinkel2004 Eberli et al 2004 Isern et al 2004)
Widely recognized as among the most commondepositional stratal patterns clinoforms are one of thefundamental building blocks of seismic- and sequence-stratigraphic models (eg Mitchum et al 1977Vail et al 1977 Van Wagoner et al 1988) Howevermost documented seismic clinoforms are related to largeshelf-edge deltas developed in margins of deep-water ba-sins where a clinoformmay have significant (high tens tohundreds of meters) accommodation and therefore bereadily apparent In other environments those havingshallow water depth and less accommodation the clino-forms are thinner and more difficult to identify usingseismic data Prograding deltaic systems developed inshallow-water environments such as along the coast
1The University of Texas at Austin Jackson School of Geosciences Bureau of Economic Geology Austin Texas USA E-mail hongliuzengbegutexasedu
2China University of Petroleum Beijing China E-mail xmzhucupeducn3Research Institute of Petroleum Exploration and Development PetroChina Beijing China E-mail zrkpetrochinacomcnManuscript received by the Editor 25 February 2013 published online 6 August 2013 This paper appears in INTERPRETATION Vol 1 No 1
(August 2013) p SA35ndashSA51 18 FIGS 1 TABLEhttpdxdoiorg101190INT-2013-00171 copy 2013 Society of Exploration Geophysicists and American Association of Petroleum Geologists All rights reserved
t
Special section Interpreting stratigraphy from geophysical data
Interpretation August 2013 SA35
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
in shallow-marine on-shelf intracratonic basins and inpostrift continental basins are especially hard to recog-nize using seismic data In these areas where sedimentsare only several meters to low tens of meters thick seis-mic clinoform patterns are commonly poorly imaged Asa result these clinoforms have received much less atten-tion from seismic interpreters In fact except for somemoderately thin sequences that can be recognized asldquoshingledrdquo clinoform complexes (Mitchum et al 1977)many thin deltaic sequences have probably been mistak-enly interpreted as other facies because they lack dis-tinctive seismic clinoforms In this study we defineseismic nonclinoforms (or subseismic clinoforms) asseismic events produced by prograding depositional se-quences that cannot be recognized visually as seismicclinoforms
The purpose of this study is to discuss and interpretthin deltas and prograding depositional systems belowseismic detection power Geologic and seismic indica-tions of deltaic systems are discussed The limits ofusing clinoform seismic facies to characterize deltaicsystems are pointed out Specific examples of subsur-face delta sequences without clinoform geometry onseismic sections are described and evaluated Seismicresolution control on imaging of clinoform seismic ar-chitecture is investigated Seismic techniques that canbe used to detect nonclinoform sequences are outlined
In this paper carbonate progradational systemsare discussed to a lesser degree Although lithologyand depositional processes in carbonate depositionalsequences are different from those in clastic systemslinks between clinoformal surfaces and depositionalratewater depth are similar which leads to similarimpedance architecture and comparable seismic faciesTherefore our observations in deltas could safely beapplied to carbonate systems and vice versa
Indication of deltaic systemsDeltaic systems show a wide complexity in the geo-
logic record Many of these systems can be interpretedin seismic data in certain situations An understandingof the geologic conditions of delta sequence develop-ment is essential to predict their seismic responsesFollowing is a brief description of various deltaic sys-tems and how they relate to seismic interpretability
Deltas in modern and geologic recordGalloway (1975) defines a delta as ldquoa contiguous
mass of sediment partly subaerial deposited aroundthe point where a stream enters a standing body ofwaterrdquo Galloway (1975) also classifies deltas into threebasic types or end members on the basis of the energysource that dominates the deltaic building processfluvial-dominated delta wave-dominated delta andtide-dominated delta These basic delta types are char-acterized by significantly different landform geometry(Figure 2) Fluvial-dominated deltas are elongate tolobate in shape whereas wave- and tide-dominated del-tas are arcuate and funnel shaped respectively Faciespatterns associated with each delta type are also differ-ent Adding to the complexity although a deltaic systemmay be controlled by one of the energy sources otherenergy sources are usually also active to some degreeleading to mixed geometry and facies patterns amongthe end members
Postma (1990) further classifies fluvial-dominateddeltaic systems on the basis of water depth in the re-ceiving basin Shallow-water deltas are developed inwater depths of low tens of meters which would in-clude on-shelf or ldquoshelf-typerdquo deltas (Ethridge andWescott 1984) in marine basins and lacustrine andother deltas related to other shelves Shallow-water del-tas are normally represented by three physiographiczones mdash delta plain delta front and prodelta mdash
similar to those in standard models of fluvial-dominateddeltas (eg Galloway and Hobday 1983) The slopenear the river mouth and the delta-front can be gentle(shoal-water type) or steep (Gilbert-type) dependingon the channel depth versus the basin depth The
QAe1675
UndathemClinothem
Basement
Undaform ClinoformLand
Fondothem
Fondoform
Depth ofwave base
Seasurface
Figure 1 Diagram showing the original concept of the clino-form defined by Rich (1951)
Fluvial dominated
Tide dominated
Wave dominated
Tidal
Lafourche(Mississippi)
Lobate
Elongate
Rhone River
ModernMississippi
Gulf of Papua
0 10 mi
QAe1676
Current
0 10 mi
0 10 mi
0 10 mi
Figure 2 Modern examples of three basic types of deltas(modified from Fisher et al 1969)
SA36 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
general stratigraphic architecture of a fluvial-dominated shallow-water delta is summarized inFigure 3a In the dip (basinward) profile individualdelta lobes that formed in outbuilding deltaic episodescompose a clinoform complex with sandy sedimentsmostly accumulated in the upper portion of the com-plex (topsets and upper foresets) The combinationof the sandy sediments forms a lithostratigraphic unithaving a relatively smooth top and probably an unevenbase In the strike section multiple delta lobes formedat different times and accumulated as irregular-shapedmounds rarely showing parallel internal stratal beddingin seismic sections
According to Postma (1990) deep-water deltas occurin water depths deeper than tens of meters to hundredsof meters and include shelf-edge deltas ldquoslope-typerdquodeltas (Ethridge and Wescott 1984) and other systemsnot necessarily related to true shelf breaks (eg in afault-controlled deep lake) The biggest difference be-tween deep-water deltas and shallow-water deltas isthat in addition to the three physiographic zonesfound in shallow-water deltas deep-water deltas alsoextend to a suspension settling and gravity-driven masstransport zone and a deep-water turbidite zone beyondthe normal prodelta zone on the long inclined muddybasin floor (Figure 3b) Sands in this system wouldbe preferentially distributed at the top (delta-plainand delta-front sands) and base (turbidites) separatedby thick muddy sediments (prodelta and deep-water
mudstones) Internal stratal bedding is relativelysmooth and easy to correlate in dip and strike sections
Shallow-water deltaic sedimentation is a commonprocess in modern environments Examples includeLena and Volga deltas in marine basins (Olariu andBhattacharya 2006) and Wax Lake Atchafalaya (Olariuand Bhattacharya 2006) and Poyang Lake deltas
a) Sigmoid
b) Oblique
c) Complex sigmoid-oblique
d) Shingled
QAe1679
Figure 4 Reflection configurations of fluvial- and wave-dominated deltas (modified from Mitchum et al [1977]initially interpreted by Mitchum et al [1977] and Sangreeand Widmier [1977] and reinterpreted by Berg [1982])
25 Hz
100 Hz
50 Hz
60 Hz
30 Hz
40 Hz
Velocity (ms)
Rec
ogni
zabl
e pr
ogra
ding
seq
(m
)
80 Hz
4000 000600050002 3000
20
0
40
60
80
100
120
140
20
0
40
60
80
100
120
140
Rec
ogni
zabl
e pr
ogra
ding
seq
(T
wo-
way
tim
e m
s)
20 Hz
Clastics
Carbonates
200 Hz
QAe1680
Figure 5 Hmin in time and depth as a function of the pre-dominant frequency of the seismic data and the velocity ofprograding sediments
Shallow-water delta
Deep-water delta
Dip section
Strike section
Meters to low tens of meters
High tens to hundreds of meters
1
5
4
32
13
2
Sandstone Shale
QAe1678
a)
b)
Figure 3 Models of fluvial-dominated deltas illustratingtheir internal clinoform framework and gross sand distribu-tion patterns (a) Shallow-water delta (b) deep-waterdelta 1 frac14 delta plain 2 frac14 delta front 3 frac14 prodelta 4 frac14suspension settling and gravity-driven mass transport zoneand 5 = deep-water turbidite zone
Interpretation August 2013 SA37
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(Zou et al 2008) in lacustrine basins Several authorsinvestigate many ancient subsurface examples of shal-low-water deltas deposited in shallow intracratonic sea-ways (eg Busch 1959 1971 Cleaves and Broussard1980 Rasmussen et al 1985 Bhattacharya and Walker1991 Li et al 2011 Olariu et al 2012) and in lacustrinebasins (eg Cretaceous Songliao Basin Lou et al 1999Triassic Ordos Basin Zou et al 2008) However com-
pared with the large number of investigations of deep-water deltas or deltas at the shelf edge (eg Carvajaland Steel 2009 Covault et al 2009 Dixon et al 2012)the number of shallow-water deltas described in an-cient deposits is very limited
Deltas represented by clinoform seismic faciesMitchum et al (1977) promote the use of external
shape and internal configuration onseismic profiles to interpret stratalconfiguration facies patterns and depo-sitional environments of progradingstratigraphic sequences In particulartheir recognition of sigmoid obliquecomplex and shingled clinoform seismicfacies (Figure 4) and the general geologicinterpretation of these facies establishesa foundation for stratigraphic evaluationof seismic clinoforms A sigmoid clino-form pattern (Figure 4a) refers to a rela-tively low-energy sedimentary regimean oblique facies (Figure 4b) would oc-cur in a relatively high-energy sedimen-tary regime A complex sigmoid-obliquemodel (Figure 4c) results from alternat-ing high- and low-energy sedimentaryregimes Whereas these three types ofclinoforms are associated with deep-water basins a shingled clinoform
configuration (Figure 4d) represents depositional unitsprograding into shallow waters
Berg (1982) further links different clinoform con-figurations to some distinctive delta types The sig-moid oblique and complex sigmoid-oblique patterns(Figure 4andash4c) are representative seismic facies of adeep-water fluvial-dominated delta The sigmoid seismicpattern is composed of continuous and S-shapedclinoforms (Figure 4a) Without toplapping sigmoid pat-terns usually occur in low-energy delta interlobe areaslacking sandy deposits The oblique pattern (Figure 4b)is characterized by clinoforms that terminate updip bytoplap and downdip by downlap that bound the deltaicsequence This pattern represents a high-energy deltawhere the sand-rich delta plain is coincident with theupper horizontal events (undaform) The seismic clino-form is equivalent to shale-prone prodelta facies The ab-sence of stacking of horizontal events in the delta plainsuggests sediment bypassing on a stable shelf The com-plex sigmoid-oblique pattern (Figure 4c) is a result ofalternate high-energy sandy deposition (oblique) andlow-energy shaly deposition (sigmoid) that occurred indelta-lobe shifting during delta system outbuildingThe shingled pattern (Figure 4d) appears to indicate awave-dominated delta in shallow water Developmentof a wave-dominated delta seems to require a stable shal-low depositional shelf Less studied and documentedtide-dominated deltas are difficult to identify using sim-ple seismic clinoform patterns
Table 1 Hmin in meters as a function of the predominant frequency ofthe seismic data and the velocity of prograding sediments Typicalindustry data are characterized by a predominant frequency from 20 to50 Hz
f (Hz) V frac14 2000m∕s
V frac14 3000m∕s
V frac14 4000m∕s
V frac14 5000m∕s
V frac14 6000m∕s
20 500 750 1000 1250 1500
25 400 600 800 1000 1200
30 333 500 667 833 1000
40 250 375 500 625 750
50 200 300 400 500 600
60 167 250 333 417 500
80 125 187 250 312 375
100 100 150 200 250 300
200 50 75 100 125 150
0 1200 km
BEIJINGPeoplersquos Republic
of China
0 500 km
48deg
46deg
44deg
50deg126deg 128deg 130deg
124deg122deg
Qiqihar
Harbin
Changchun
DaqingOilfieldStudy
area
SongliaoBasin
QAe1681
N
Figure 6 Cretaceous Songliao Basin of China showing thestudy area in the Qijia Depression near the Daqing Oilfield
SA38 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Limits of clinoform seismic faciesBarring any data quality issues related to acquisition
and processing our ability to use clinoform seismicstratigraphy to recognize progradational depositionalsequences is largely limited by seismic resolution
To visually identify a clinoform pattern within a seis-mic stratigraphic mapping unit one has to recognize atleast two seismic events with one offlapping the otherIn other words the unit has to be at least as thick as thewidth of two seismic events (one wavelength or cycle)in two-way traveltime We call the thickness of such aseismic stratigraphic mapping unit clinoform detectionlimit
Hmin frac14 1000∕f (1)
where f denotes the predominant frequency of the seis-mic data in hertz (Hz) and Hmin is the clinoform detec-tion limit in milliseconds (ms) The clinoform detection
limit in depth is related to the predominant frequency ofthe seismic data and the velocity of the prograding sedi-ments (Figure 5 Table 1)
Hmin frac14 V∕2f (2)
where V denotes velocity of the sediments in meters persecond (m∕s) and Hmin is the clinoform detection limitin meters (m) Most modern seismic data sets are char-acterized by a predominant frequency ranging from20 to 100 Hz corresponding to Hmin (in time) from10 to 50 ms In a typical clastic basin the velocity ofsandstones and shales is usually between 2000 and4000 m∕s resulting in a Hmin (in depth) of 10 to100 m in a carbonate formation rock velocity is signifi-cantly higher (mostly 5000 minus 6000 m∕s) and Hmin (indepth) increases sizably (25ndash150 m)
These simple calculations reveal that seismic clino-form recognition is reserved to thicker prograding
rsquoAA
G21
G42G41G32G31
G22
G12
SQ1SS1SS2
SS3
SS4
SS5
SS6
SQ2
SQ3
G11
Tra
velti
me
(ms)
T1
T2
a)Basinward
2 km2 km
b)
SQ1
SQ2
SQ3
T1
T2
Rel
ativ
e ge
olog
ic ti
me
a
b
c
SS1
SS2
SS3
SS4
SS5
SS6
G21
G42G41G32G31G22
G12G11
Third-orderseq boundary
SP DT High-ordersequence
Fault
fifth fourth third
fifth fourth third
- +
Amplitude
A
Arsquo
BBrsquo
QAe1682
2 km
1200
1300
1400
1500
1600
1700
Figure 7 A dip well-seismic section illustrat-ing the high-frequency depositional sequenceframework and internal nonclinoform reflec-tion pattern in the Cretaceous Qijia Depres-sion (modified from Zeng et al 2012) SeeFigure 7a for position (a) Traveltime sectionshowing wireline logs sequence definitionand well-seismic correlation (b) Wheeler-transformed section flattened in relativegeologic time for easy viewing of internalreflection characteristics Positions of stratalslices in Figure 10 are labeled a b and c SP frac14spontaneous potential log DT = sonic log
Interpretation August 2013 SA39
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
depositional sequences or the thicker part of a prograd-ing depositional sequence Sequences thinner thanHminnormally do not show as clinoforms on seismic profilesDepending on the current status of seismic data qualityin basins around the world a large number of shallow-water deltas would fall below Hmin because they devel-oped in water depths shallower than tens of meters
These shallow-water deltas are good candidates to bereflected as nonclinoform seismic patterns Accord-ingly the interpretation of deltas needs to go beyondthe recognition of seismic clinoforms Lacking visibleclinoforms shallow-water deltas would routinely gounrecognized by seismic interpreters Seismic faciesof those nonclinoform sequences are our major concernin following sections
Examples of seismic nonclinoform deltasIn this section three investigations are presented
as examples of seismic nonclinoform deltas Withoutvisible seismic clinoforms seismic geomorphologypatterns on amplitude stratal slices provide vital infor-mation for interpreting thin deltaic systems The pro-duction of stratal slices has followed the procedurediscussed in Zeng et al (1998a 1998b) Where availableconventional cores and wireline logs have been used tocalibrate the interpretations in these studies
Qijia depression Songliao Basin ChinaThe Songliao Basin of China is a large-scale
Mesozoic-Cenozoic lacustrine basin covering an areaof more than 250000 km2 (Figure 6) In lower throughupper Cretaceous strata postrift deposits as thick as3000 to 4000 m unconformably overlie synrift strataand extend beyond the fault blocks to cover the wholebasin (Feng et al 2010) Lacking true shelf breaks seis-mic clinoforms can be seen only along major delta axeswhere fluvial systems transported abundant sedimentto the deep part of the lake in the center of the basin
B B
+-
Amplitude2 km
50 m
s50
ms
QAe1683
50 m
s
a
b
c
Figure 8 Strike seismic section showing the internal reflec-tion pattern in the Cretaceous Qijia Depression The expectedmounded seismic configuration for a ldquonormalrdquo deltaic system(Figure 3b) does not exist The regional structural trend is cor-rected for a better view of internal reflection characteristicsPositions of stratal slices in Figure 10 are labeled a b and cSee Figure 7a for position
QAe1684
10 m
Del
ta fr
ont
Sha
llow
lake
Depth(m)
Limestone
Shale
Sandstone
sotohp eroCseicafbuSnoitces deroC
GR DT
a)
b)
c)
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2120
2133
a)
b)
c)
Figure 9 Description of a cored section in awell in the Qijia Depression showing Creta-ceous fluvial-dominated shallow-water deltadeposits Arrows denote upward-coarseninggrain-size trends (a) Shallow-lake Ostracodalimestone (b) trough-cross-stratified (arrow)fine-grained distributary-channel sandstone(c) medium-grained blocky sandstone withshale lag (arrow) on the scoured distributary-channel base Cores are oriented up (shal-lower) to the left
SA40 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(eg in the Daqing Oilfield area) Much of the deltaicsediment was deposited in very gentle slopes aroundthe basin margin in shallow waters lacking well-developed clinoforms
In the Qijia Depression (Figure 6) deltaic sedimentsconsist of gray and dark-gray mudstone interbeddedwith sandstone and siltstone A wireline-log-basedsequence-stratigraphic correlation (Figure 7a) revealedmultiple higher order sequences (G11 through SS1) inthree third-order sequences (SQ1 through SQ3) in theQingshankou Formation (Zeng et al 2012) In this22-km-long dip-oriented section thickness changesfrom updip to downdip are minor revealing a very gen-tle slope at the time of deposition Each of the higherorder sequences has an average thickness of approxi-mately 40 m which is composed of a relative lowstandsystems tract (LST) at the bottom and a relative high-stand systems tract (HST) at the top with roughly equalthickness (20 m)
A Wheeler-transformed equivalent of Figure 7a isrealized with stratal slicing processing (Figure 7b)which shows a good correlation between well-baseddepositional sequences and seismic events The 3Dseismic data have a frequency range of 10 to 80 Hzand a dominant frequency of 50 Hz In this formationaverage velocity is 4000 m∕s and the calculated Hminis 40 m (Table 1) This doubles the Hmin in this forma-tion for seismic imaging of clinoform complexes ineither LST or HST As a result seismic clinoformsare not imaged Instead these seismic events can beclassified as subparallel to discontinuous variable-amplitude seismic facies Each pair of seismic events(peak at bottom and trough at top) in each of thehigh-frequency sequences roughly represents a high-frequency sequence composed of a relative LST at thebottom and a relative HST at the top A strike seismicsection (Figure 8) shows a seismic facies distributionsimilar to that in the dip section (Figure 7) and fails
Fault- +
Amplitude
Shoreline Channellobe
Deltaplain
Deltafront
Prodeltalake
Direction ofprogradation
2 km2 km2 km
QAe1685
a)
c)
e)
b)
d)
f)
Figure 10 Three amplitude stratal slices (ac and e) at three high-frequency sequences(G31 G41 and SS2 respectively in Figure 7band labeled as a b and c in Figures 7b and 8)These slices interpreted as shallow-water del-tas are shown in (b d and f) respectivelyShorelines interpreted in (d and f) refer toposition of the successive shorelines duringprogradation
Interpretation August 2013 SA41
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
to reveal any seismic reflection configuration thatresembles the mound geometry associated with typicalprograding delta clinoforms (Figure 3b)
Lithology grain-size trend and sedimentary struc-ture were observed in conventional cores providingmore direct evidence for classifying depositional faciesBy describing more than 1300 m of core in 11 wells inthe area we recognized that most subfacies in the coreare related to fluvial-dominated deltaic deposition Forexample in a long cored section (Figure 9) a typicalfacies cycle (from bottom to top) includes gray shaleand thin limestone (Figure 9a) representing shallow-lake deposition trough-cross-stratified fine-grainedsandstone (Figure 9b) from the distributary channeland medium-grained blocky sandstone with shale-clastlag (Figure 9c) on the scoured distributary-channelbase in the delta front There are abundant ostracodfossils (eg Cypridea Candona Mongolocypris andZiziphocypris) identified in the limestones andshales all indicative of a shallow-water environmentRanging from 4- to 15-m thick the upward-coarseningsequences are a result of progradational processes ina shallow-water deltaic system (eg Olariu and Bhatta-charya 2006)
A set of stratal slices was constructed in the intervalbetween reference events T1 and T2 from stacked andmigrated data (Figure 7a) All the stratal slices roughlyfollow individual seismic events that are parallel toone another Selected slices (Figure 10a 10c and10e) represent three thin LST deltaic depositional sys-tems in high-order sequences The most striking seismicgeomorphologic features in these stratal slices are nu-merous channel patterns and associated amplitudeanomalies of different shapes representing variousdeltaic environments (Figure 10b 10d and 10f)Differences in the facies patterns reflect relative mar-gin-to-basin positions in the gentle slope of a postriftlacustrine basin During deposition of the high-frequency sequence SS2 (Figure 10a and 10b) the lakewas at its maximum depth and extent and the studyarea was a delta front Distributary channels extendedfar into the basin and were rarely exposed before burialA fringing sandy delta front was lacking Later duringdeposition of the high-frequency sequences G41(Figure 10c and 10d) and G31 (Figure 10e and 10f)the lake diminished in area after repeated deltaic-deposition episodes The study area is located in theshoreline area which has a narrower delta-front zoneThe deltaic system prograded on a smaller scale withdeltaic lobes forming one in front of another attachedto shorter distributary channels which terminated atthe shoreline at the time of deposition Multiple shore-line positions can be determined on the basis of channelterminations (Figure 10c and 10d) or amplitude zoning(Figure 10e and 10f) showing a general direction ofdeltaic progradation
Miocene deltas at the Gulf of MexicoLouisiana United States
Starfak and Tiger Shoal fields of offshore LouisianaUnited States (Figure 11) lie along the western periph-ery of the ancestral Mississippi River area Located inthe Oligocene-Miocene Detachment Province of thenorth Gulf Coast continental margin (Diegel et al1995) Miocene deposits are largely controlled bydown-to-the-basin listric growth faults that sole on aregional detachment zone above the Oligocene sectionSalt tectonics and growth faulting resulted in a greatthickness of deltaic and other on-shelf sediments duringa period of high sedimentation rates Interpreted depo-sitional environments include lowstand progradingwedge slope fan and basin-floor fan beyond the shelfedge incised valley highstand delta and transgressivefacies and coastal plain coastal delta and inner-shelfmarine deposits in the coastal area (Hentz and Zeng2003)
All these Miocene depositional systems are com-posed of interbedded sandstone and shale units withsandstones varying widely in thickness and rangingfrom 1 to 40 m Although the study area is situatedin a passive continental margin a representative dipseismic section across the area (Figure 12) demon-strates mostly parallel to divergent seismic facies
TEXAS
LOUISIANA
MISSISSIPPI
3D surveysField
N
VERMILIONAREA
SOUTH MARSHISLAND AREA
North LightHouse Point
TigerShoal
Starfak C
LOUISIANA
MARSH ISLAND
C
A
A
0
0
5 mi
8 km
B
B
LightHousePoint
Trinity Shoal
Amber Complex
Mound Point
Fig 13
QAe1686
Figure 11 Location of Starfak and Tiger Shoal fields 3Dseismic surveys and wells in the Louisiana Gulf Coast
SA42 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
in shallow-marine on-shelf intracratonic basins and inpostrift continental basins are especially hard to recog-nize using seismic data In these areas where sedimentsare only several meters to low tens of meters thick seis-mic clinoform patterns are commonly poorly imaged Asa result these clinoforms have received much less atten-tion from seismic interpreters In fact except for somemoderately thin sequences that can be recognized asldquoshingledrdquo clinoform complexes (Mitchum et al 1977)many thin deltaic sequences have probably been mistak-enly interpreted as other facies because they lack dis-tinctive seismic clinoforms In this study we defineseismic nonclinoforms (or subseismic clinoforms) asseismic events produced by prograding depositional se-quences that cannot be recognized visually as seismicclinoforms
The purpose of this study is to discuss and interpretthin deltas and prograding depositional systems belowseismic detection power Geologic and seismic indica-tions of deltaic systems are discussed The limits ofusing clinoform seismic facies to characterize deltaicsystems are pointed out Specific examples of subsur-face delta sequences without clinoform geometry onseismic sections are described and evaluated Seismicresolution control on imaging of clinoform seismic ar-chitecture is investigated Seismic techniques that canbe used to detect nonclinoform sequences are outlined
In this paper carbonate progradational systemsare discussed to a lesser degree Although lithologyand depositional processes in carbonate depositionalsequences are different from those in clastic systemslinks between clinoformal surfaces and depositionalratewater depth are similar which leads to similarimpedance architecture and comparable seismic faciesTherefore our observations in deltas could safely beapplied to carbonate systems and vice versa
Indication of deltaic systemsDeltaic systems show a wide complexity in the geo-
logic record Many of these systems can be interpretedin seismic data in certain situations An understandingof the geologic conditions of delta sequence develop-ment is essential to predict their seismic responsesFollowing is a brief description of various deltaic sys-tems and how they relate to seismic interpretability
Deltas in modern and geologic recordGalloway (1975) defines a delta as ldquoa contiguous
mass of sediment partly subaerial deposited aroundthe point where a stream enters a standing body ofwaterrdquo Galloway (1975) also classifies deltas into threebasic types or end members on the basis of the energysource that dominates the deltaic building processfluvial-dominated delta wave-dominated delta andtide-dominated delta These basic delta types are char-acterized by significantly different landform geometry(Figure 2) Fluvial-dominated deltas are elongate tolobate in shape whereas wave- and tide-dominated del-tas are arcuate and funnel shaped respectively Faciespatterns associated with each delta type are also differ-ent Adding to the complexity although a deltaic systemmay be controlled by one of the energy sources otherenergy sources are usually also active to some degreeleading to mixed geometry and facies patterns amongthe end members
Postma (1990) further classifies fluvial-dominateddeltaic systems on the basis of water depth in the re-ceiving basin Shallow-water deltas are developed inwater depths of low tens of meters which would in-clude on-shelf or ldquoshelf-typerdquo deltas (Ethridge andWescott 1984) in marine basins and lacustrine andother deltas related to other shelves Shallow-water del-tas are normally represented by three physiographiczones mdash delta plain delta front and prodelta mdash
similar to those in standard models of fluvial-dominateddeltas (eg Galloway and Hobday 1983) The slopenear the river mouth and the delta-front can be gentle(shoal-water type) or steep (Gilbert-type) dependingon the channel depth versus the basin depth The
QAe1675
UndathemClinothem
Basement
Undaform ClinoformLand
Fondothem
Fondoform
Depth ofwave base
Seasurface
Figure 1 Diagram showing the original concept of the clino-form defined by Rich (1951)
Fluvial dominated
Tide dominated
Wave dominated
Tidal
Lafourche(Mississippi)
Lobate
Elongate
Rhone River
ModernMississippi
Gulf of Papua
0 10 mi
QAe1676
Current
0 10 mi
0 10 mi
0 10 mi
Figure 2 Modern examples of three basic types of deltas(modified from Fisher et al 1969)
SA36 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
general stratigraphic architecture of a fluvial-dominated shallow-water delta is summarized inFigure 3a In the dip (basinward) profile individualdelta lobes that formed in outbuilding deltaic episodescompose a clinoform complex with sandy sedimentsmostly accumulated in the upper portion of the com-plex (topsets and upper foresets) The combinationof the sandy sediments forms a lithostratigraphic unithaving a relatively smooth top and probably an unevenbase In the strike section multiple delta lobes formedat different times and accumulated as irregular-shapedmounds rarely showing parallel internal stratal beddingin seismic sections
According to Postma (1990) deep-water deltas occurin water depths deeper than tens of meters to hundredsof meters and include shelf-edge deltas ldquoslope-typerdquodeltas (Ethridge and Wescott 1984) and other systemsnot necessarily related to true shelf breaks (eg in afault-controlled deep lake) The biggest difference be-tween deep-water deltas and shallow-water deltas isthat in addition to the three physiographic zonesfound in shallow-water deltas deep-water deltas alsoextend to a suspension settling and gravity-driven masstransport zone and a deep-water turbidite zone beyondthe normal prodelta zone on the long inclined muddybasin floor (Figure 3b) Sands in this system wouldbe preferentially distributed at the top (delta-plainand delta-front sands) and base (turbidites) separatedby thick muddy sediments (prodelta and deep-water
mudstones) Internal stratal bedding is relativelysmooth and easy to correlate in dip and strike sections
Shallow-water deltaic sedimentation is a commonprocess in modern environments Examples includeLena and Volga deltas in marine basins (Olariu andBhattacharya 2006) and Wax Lake Atchafalaya (Olariuand Bhattacharya 2006) and Poyang Lake deltas
a) Sigmoid
b) Oblique
c) Complex sigmoid-oblique
d) Shingled
QAe1679
Figure 4 Reflection configurations of fluvial- and wave-dominated deltas (modified from Mitchum et al [1977]initially interpreted by Mitchum et al [1977] and Sangreeand Widmier [1977] and reinterpreted by Berg [1982])
25 Hz
100 Hz
50 Hz
60 Hz
30 Hz
40 Hz
Velocity (ms)
Rec
ogni
zabl
e pr
ogra
ding
seq
(m
)
80 Hz
4000 000600050002 3000
20
0
40
60
80
100
120
140
20
0
40
60
80
100
120
140
Rec
ogni
zabl
e pr
ogra
ding
seq
(T
wo-
way
tim
e m
s)
20 Hz
Clastics
Carbonates
200 Hz
QAe1680
Figure 5 Hmin in time and depth as a function of the pre-dominant frequency of the seismic data and the velocity ofprograding sediments
Shallow-water delta
Deep-water delta
Dip section
Strike section
Meters to low tens of meters
High tens to hundreds of meters
1
5
4
32
13
2
Sandstone Shale
QAe1678
a)
b)
Figure 3 Models of fluvial-dominated deltas illustratingtheir internal clinoform framework and gross sand distribu-tion patterns (a) Shallow-water delta (b) deep-waterdelta 1 frac14 delta plain 2 frac14 delta front 3 frac14 prodelta 4 frac14suspension settling and gravity-driven mass transport zoneand 5 = deep-water turbidite zone
Interpretation August 2013 SA37
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(Zou et al 2008) in lacustrine basins Several authorsinvestigate many ancient subsurface examples of shal-low-water deltas deposited in shallow intracratonic sea-ways (eg Busch 1959 1971 Cleaves and Broussard1980 Rasmussen et al 1985 Bhattacharya and Walker1991 Li et al 2011 Olariu et al 2012) and in lacustrinebasins (eg Cretaceous Songliao Basin Lou et al 1999Triassic Ordos Basin Zou et al 2008) However com-
pared with the large number of investigations of deep-water deltas or deltas at the shelf edge (eg Carvajaland Steel 2009 Covault et al 2009 Dixon et al 2012)the number of shallow-water deltas described in an-cient deposits is very limited
Deltas represented by clinoform seismic faciesMitchum et al (1977) promote the use of external
shape and internal configuration onseismic profiles to interpret stratalconfiguration facies patterns and depo-sitional environments of progradingstratigraphic sequences In particulartheir recognition of sigmoid obliquecomplex and shingled clinoform seismicfacies (Figure 4) and the general geologicinterpretation of these facies establishesa foundation for stratigraphic evaluationof seismic clinoforms A sigmoid clino-form pattern (Figure 4a) refers to a rela-tively low-energy sedimentary regimean oblique facies (Figure 4b) would oc-cur in a relatively high-energy sedimen-tary regime A complex sigmoid-obliquemodel (Figure 4c) results from alternat-ing high- and low-energy sedimentaryregimes Whereas these three types ofclinoforms are associated with deep-water basins a shingled clinoform
configuration (Figure 4d) represents depositional unitsprograding into shallow waters
Berg (1982) further links different clinoform con-figurations to some distinctive delta types The sig-moid oblique and complex sigmoid-oblique patterns(Figure 4andash4c) are representative seismic facies of adeep-water fluvial-dominated delta The sigmoid seismicpattern is composed of continuous and S-shapedclinoforms (Figure 4a) Without toplapping sigmoid pat-terns usually occur in low-energy delta interlobe areaslacking sandy deposits The oblique pattern (Figure 4b)is characterized by clinoforms that terminate updip bytoplap and downdip by downlap that bound the deltaicsequence This pattern represents a high-energy deltawhere the sand-rich delta plain is coincident with theupper horizontal events (undaform) The seismic clino-form is equivalent to shale-prone prodelta facies The ab-sence of stacking of horizontal events in the delta plainsuggests sediment bypassing on a stable shelf The com-plex sigmoid-oblique pattern (Figure 4c) is a result ofalternate high-energy sandy deposition (oblique) andlow-energy shaly deposition (sigmoid) that occurred indelta-lobe shifting during delta system outbuildingThe shingled pattern (Figure 4d) appears to indicate awave-dominated delta in shallow water Developmentof a wave-dominated delta seems to require a stable shal-low depositional shelf Less studied and documentedtide-dominated deltas are difficult to identify using sim-ple seismic clinoform patterns
Table 1 Hmin in meters as a function of the predominant frequency ofthe seismic data and the velocity of prograding sediments Typicalindustry data are characterized by a predominant frequency from 20 to50 Hz
f (Hz) V frac14 2000m∕s
V frac14 3000m∕s
V frac14 4000m∕s
V frac14 5000m∕s
V frac14 6000m∕s
20 500 750 1000 1250 1500
25 400 600 800 1000 1200
30 333 500 667 833 1000
40 250 375 500 625 750
50 200 300 400 500 600
60 167 250 333 417 500
80 125 187 250 312 375
100 100 150 200 250 300
200 50 75 100 125 150
0 1200 km
BEIJINGPeoplersquos Republic
of China
0 500 km
48deg
46deg
44deg
50deg126deg 128deg 130deg
124deg122deg
Qiqihar
Harbin
Changchun
DaqingOilfieldStudy
area
SongliaoBasin
QAe1681
N
Figure 6 Cretaceous Songliao Basin of China showing thestudy area in the Qijia Depression near the Daqing Oilfield
SA38 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Limits of clinoform seismic faciesBarring any data quality issues related to acquisition
and processing our ability to use clinoform seismicstratigraphy to recognize progradational depositionalsequences is largely limited by seismic resolution
To visually identify a clinoform pattern within a seis-mic stratigraphic mapping unit one has to recognize atleast two seismic events with one offlapping the otherIn other words the unit has to be at least as thick as thewidth of two seismic events (one wavelength or cycle)in two-way traveltime We call the thickness of such aseismic stratigraphic mapping unit clinoform detectionlimit
Hmin frac14 1000∕f (1)
where f denotes the predominant frequency of the seis-mic data in hertz (Hz) and Hmin is the clinoform detec-tion limit in milliseconds (ms) The clinoform detection
limit in depth is related to the predominant frequency ofthe seismic data and the velocity of the prograding sedi-ments (Figure 5 Table 1)
Hmin frac14 V∕2f (2)
where V denotes velocity of the sediments in meters persecond (m∕s) and Hmin is the clinoform detection limitin meters (m) Most modern seismic data sets are char-acterized by a predominant frequency ranging from20 to 100 Hz corresponding to Hmin (in time) from10 to 50 ms In a typical clastic basin the velocity ofsandstones and shales is usually between 2000 and4000 m∕s resulting in a Hmin (in depth) of 10 to100 m in a carbonate formation rock velocity is signifi-cantly higher (mostly 5000 minus 6000 m∕s) and Hmin (indepth) increases sizably (25ndash150 m)
These simple calculations reveal that seismic clino-form recognition is reserved to thicker prograding
rsquoAA
G21
G42G41G32G31
G22
G12
SQ1SS1SS2
SS3
SS4
SS5
SS6
SQ2
SQ3
G11
Tra
velti
me
(ms)
T1
T2
a)Basinward
2 km2 km
b)
SQ1
SQ2
SQ3
T1
T2
Rel
ativ
e ge
olog
ic ti
me
a
b
c
SS1
SS2
SS3
SS4
SS5
SS6
G21
G42G41G32G31G22
G12G11
Third-orderseq boundary
SP DT High-ordersequence
Fault
fifth fourth third
fifth fourth third
- +
Amplitude
A
Arsquo
BBrsquo
QAe1682
2 km
1200
1300
1400
1500
1600
1700
Figure 7 A dip well-seismic section illustrat-ing the high-frequency depositional sequenceframework and internal nonclinoform reflec-tion pattern in the Cretaceous Qijia Depres-sion (modified from Zeng et al 2012) SeeFigure 7a for position (a) Traveltime sectionshowing wireline logs sequence definitionand well-seismic correlation (b) Wheeler-transformed section flattened in relativegeologic time for easy viewing of internalreflection characteristics Positions of stratalslices in Figure 10 are labeled a b and c SP frac14spontaneous potential log DT = sonic log
Interpretation August 2013 SA39
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
depositional sequences or the thicker part of a prograd-ing depositional sequence Sequences thinner thanHminnormally do not show as clinoforms on seismic profilesDepending on the current status of seismic data qualityin basins around the world a large number of shallow-water deltas would fall below Hmin because they devel-oped in water depths shallower than tens of meters
These shallow-water deltas are good candidates to bereflected as nonclinoform seismic patterns Accord-ingly the interpretation of deltas needs to go beyondthe recognition of seismic clinoforms Lacking visibleclinoforms shallow-water deltas would routinely gounrecognized by seismic interpreters Seismic faciesof those nonclinoform sequences are our major concernin following sections
Examples of seismic nonclinoform deltasIn this section three investigations are presented
as examples of seismic nonclinoform deltas Withoutvisible seismic clinoforms seismic geomorphologypatterns on amplitude stratal slices provide vital infor-mation for interpreting thin deltaic systems The pro-duction of stratal slices has followed the procedurediscussed in Zeng et al (1998a 1998b) Where availableconventional cores and wireline logs have been used tocalibrate the interpretations in these studies
Qijia depression Songliao Basin ChinaThe Songliao Basin of China is a large-scale
Mesozoic-Cenozoic lacustrine basin covering an areaof more than 250000 km2 (Figure 6) In lower throughupper Cretaceous strata postrift deposits as thick as3000 to 4000 m unconformably overlie synrift strataand extend beyond the fault blocks to cover the wholebasin (Feng et al 2010) Lacking true shelf breaks seis-mic clinoforms can be seen only along major delta axeswhere fluvial systems transported abundant sedimentto the deep part of the lake in the center of the basin
B B
+-
Amplitude2 km
50 m
s50
ms
QAe1683
50 m
s
a
b
c
Figure 8 Strike seismic section showing the internal reflec-tion pattern in the Cretaceous Qijia Depression The expectedmounded seismic configuration for a ldquonormalrdquo deltaic system(Figure 3b) does not exist The regional structural trend is cor-rected for a better view of internal reflection characteristicsPositions of stratal slices in Figure 10 are labeled a b and cSee Figure 7a for position
QAe1684
10 m
Del
ta fr
ont
Sha
llow
lake
Depth(m)
Limestone
Shale
Sandstone
sotohp eroCseicafbuSnoitces deroC
GR DT
a)
b)
c)
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2120
2133
a)
b)
c)
Figure 9 Description of a cored section in awell in the Qijia Depression showing Creta-ceous fluvial-dominated shallow-water deltadeposits Arrows denote upward-coarseninggrain-size trends (a) Shallow-lake Ostracodalimestone (b) trough-cross-stratified (arrow)fine-grained distributary-channel sandstone(c) medium-grained blocky sandstone withshale lag (arrow) on the scoured distributary-channel base Cores are oriented up (shal-lower) to the left
SA40 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(eg in the Daqing Oilfield area) Much of the deltaicsediment was deposited in very gentle slopes aroundthe basin margin in shallow waters lacking well-developed clinoforms
In the Qijia Depression (Figure 6) deltaic sedimentsconsist of gray and dark-gray mudstone interbeddedwith sandstone and siltstone A wireline-log-basedsequence-stratigraphic correlation (Figure 7a) revealedmultiple higher order sequences (G11 through SS1) inthree third-order sequences (SQ1 through SQ3) in theQingshankou Formation (Zeng et al 2012) In this22-km-long dip-oriented section thickness changesfrom updip to downdip are minor revealing a very gen-tle slope at the time of deposition Each of the higherorder sequences has an average thickness of approxi-mately 40 m which is composed of a relative lowstandsystems tract (LST) at the bottom and a relative high-stand systems tract (HST) at the top with roughly equalthickness (20 m)
A Wheeler-transformed equivalent of Figure 7a isrealized with stratal slicing processing (Figure 7b)which shows a good correlation between well-baseddepositional sequences and seismic events The 3Dseismic data have a frequency range of 10 to 80 Hzand a dominant frequency of 50 Hz In this formationaverage velocity is 4000 m∕s and the calculated Hminis 40 m (Table 1) This doubles the Hmin in this forma-tion for seismic imaging of clinoform complexes ineither LST or HST As a result seismic clinoformsare not imaged Instead these seismic events can beclassified as subparallel to discontinuous variable-amplitude seismic facies Each pair of seismic events(peak at bottom and trough at top) in each of thehigh-frequency sequences roughly represents a high-frequency sequence composed of a relative LST at thebottom and a relative HST at the top A strike seismicsection (Figure 8) shows a seismic facies distributionsimilar to that in the dip section (Figure 7) and fails
Fault- +
Amplitude
Shoreline Channellobe
Deltaplain
Deltafront
Prodeltalake
Direction ofprogradation
2 km2 km2 km
QAe1685
a)
c)
e)
b)
d)
f)
Figure 10 Three amplitude stratal slices (ac and e) at three high-frequency sequences(G31 G41 and SS2 respectively in Figure 7band labeled as a b and c in Figures 7b and 8)These slices interpreted as shallow-water del-tas are shown in (b d and f) respectivelyShorelines interpreted in (d and f) refer toposition of the successive shorelines duringprogradation
Interpretation August 2013 SA41
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
to reveal any seismic reflection configuration thatresembles the mound geometry associated with typicalprograding delta clinoforms (Figure 3b)
Lithology grain-size trend and sedimentary struc-ture were observed in conventional cores providingmore direct evidence for classifying depositional faciesBy describing more than 1300 m of core in 11 wells inthe area we recognized that most subfacies in the coreare related to fluvial-dominated deltaic deposition Forexample in a long cored section (Figure 9) a typicalfacies cycle (from bottom to top) includes gray shaleand thin limestone (Figure 9a) representing shallow-lake deposition trough-cross-stratified fine-grainedsandstone (Figure 9b) from the distributary channeland medium-grained blocky sandstone with shale-clastlag (Figure 9c) on the scoured distributary-channelbase in the delta front There are abundant ostracodfossils (eg Cypridea Candona Mongolocypris andZiziphocypris) identified in the limestones andshales all indicative of a shallow-water environmentRanging from 4- to 15-m thick the upward-coarseningsequences are a result of progradational processes ina shallow-water deltaic system (eg Olariu and Bhatta-charya 2006)
A set of stratal slices was constructed in the intervalbetween reference events T1 and T2 from stacked andmigrated data (Figure 7a) All the stratal slices roughlyfollow individual seismic events that are parallel toone another Selected slices (Figure 10a 10c and10e) represent three thin LST deltaic depositional sys-tems in high-order sequences The most striking seismicgeomorphologic features in these stratal slices are nu-merous channel patterns and associated amplitudeanomalies of different shapes representing variousdeltaic environments (Figure 10b 10d and 10f)Differences in the facies patterns reflect relative mar-gin-to-basin positions in the gentle slope of a postriftlacustrine basin During deposition of the high-frequency sequence SS2 (Figure 10a and 10b) the lakewas at its maximum depth and extent and the studyarea was a delta front Distributary channels extendedfar into the basin and were rarely exposed before burialA fringing sandy delta front was lacking Later duringdeposition of the high-frequency sequences G41(Figure 10c and 10d) and G31 (Figure 10e and 10f)the lake diminished in area after repeated deltaic-deposition episodes The study area is located in theshoreline area which has a narrower delta-front zoneThe deltaic system prograded on a smaller scale withdeltaic lobes forming one in front of another attachedto shorter distributary channels which terminated atthe shoreline at the time of deposition Multiple shore-line positions can be determined on the basis of channelterminations (Figure 10c and 10d) or amplitude zoning(Figure 10e and 10f) showing a general direction ofdeltaic progradation
Miocene deltas at the Gulf of MexicoLouisiana United States
Starfak and Tiger Shoal fields of offshore LouisianaUnited States (Figure 11) lie along the western periph-ery of the ancestral Mississippi River area Located inthe Oligocene-Miocene Detachment Province of thenorth Gulf Coast continental margin (Diegel et al1995) Miocene deposits are largely controlled bydown-to-the-basin listric growth faults that sole on aregional detachment zone above the Oligocene sectionSalt tectonics and growth faulting resulted in a greatthickness of deltaic and other on-shelf sediments duringa period of high sedimentation rates Interpreted depo-sitional environments include lowstand progradingwedge slope fan and basin-floor fan beyond the shelfedge incised valley highstand delta and transgressivefacies and coastal plain coastal delta and inner-shelfmarine deposits in the coastal area (Hentz and Zeng2003)
All these Miocene depositional systems are com-posed of interbedded sandstone and shale units withsandstones varying widely in thickness and rangingfrom 1 to 40 m Although the study area is situatedin a passive continental margin a representative dipseismic section across the area (Figure 12) demon-strates mostly parallel to divergent seismic facies
TEXAS
LOUISIANA
MISSISSIPPI
3D surveysField
N
VERMILIONAREA
SOUTH MARSHISLAND AREA
North LightHouse Point
TigerShoal
Starfak C
LOUISIANA
MARSH ISLAND
C
A
A
0
0
5 mi
8 km
B
B
LightHousePoint
Trinity Shoal
Amber Complex
Mound Point
Fig 13
QAe1686
Figure 11 Location of Starfak and Tiger Shoal fields 3Dseismic surveys and wells in the Louisiana Gulf Coast
SA42 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
general stratigraphic architecture of a fluvial-dominated shallow-water delta is summarized inFigure 3a In the dip (basinward) profile individualdelta lobes that formed in outbuilding deltaic episodescompose a clinoform complex with sandy sedimentsmostly accumulated in the upper portion of the com-plex (topsets and upper foresets) The combinationof the sandy sediments forms a lithostratigraphic unithaving a relatively smooth top and probably an unevenbase In the strike section multiple delta lobes formedat different times and accumulated as irregular-shapedmounds rarely showing parallel internal stratal beddingin seismic sections
According to Postma (1990) deep-water deltas occurin water depths deeper than tens of meters to hundredsof meters and include shelf-edge deltas ldquoslope-typerdquodeltas (Ethridge and Wescott 1984) and other systemsnot necessarily related to true shelf breaks (eg in afault-controlled deep lake) The biggest difference be-tween deep-water deltas and shallow-water deltas isthat in addition to the three physiographic zonesfound in shallow-water deltas deep-water deltas alsoextend to a suspension settling and gravity-driven masstransport zone and a deep-water turbidite zone beyondthe normal prodelta zone on the long inclined muddybasin floor (Figure 3b) Sands in this system wouldbe preferentially distributed at the top (delta-plainand delta-front sands) and base (turbidites) separatedby thick muddy sediments (prodelta and deep-water
mudstones) Internal stratal bedding is relativelysmooth and easy to correlate in dip and strike sections
Shallow-water deltaic sedimentation is a commonprocess in modern environments Examples includeLena and Volga deltas in marine basins (Olariu andBhattacharya 2006) and Wax Lake Atchafalaya (Olariuand Bhattacharya 2006) and Poyang Lake deltas
a) Sigmoid
b) Oblique
c) Complex sigmoid-oblique
d) Shingled
QAe1679
Figure 4 Reflection configurations of fluvial- and wave-dominated deltas (modified from Mitchum et al [1977]initially interpreted by Mitchum et al [1977] and Sangreeand Widmier [1977] and reinterpreted by Berg [1982])
25 Hz
100 Hz
50 Hz
60 Hz
30 Hz
40 Hz
Velocity (ms)
Rec
ogni
zabl
e pr
ogra
ding
seq
(m
)
80 Hz
4000 000600050002 3000
20
0
40
60
80
100
120
140
20
0
40
60
80
100
120
140
Rec
ogni
zabl
e pr
ogra
ding
seq
(T
wo-
way
tim
e m
s)
20 Hz
Clastics
Carbonates
200 Hz
QAe1680
Figure 5 Hmin in time and depth as a function of the pre-dominant frequency of the seismic data and the velocity ofprograding sediments
Shallow-water delta
Deep-water delta
Dip section
Strike section
Meters to low tens of meters
High tens to hundreds of meters
1
5
4
32
13
2
Sandstone Shale
QAe1678
a)
b)
Figure 3 Models of fluvial-dominated deltas illustratingtheir internal clinoform framework and gross sand distribu-tion patterns (a) Shallow-water delta (b) deep-waterdelta 1 frac14 delta plain 2 frac14 delta front 3 frac14 prodelta 4 frac14suspension settling and gravity-driven mass transport zoneand 5 = deep-water turbidite zone
Interpretation August 2013 SA37
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(Zou et al 2008) in lacustrine basins Several authorsinvestigate many ancient subsurface examples of shal-low-water deltas deposited in shallow intracratonic sea-ways (eg Busch 1959 1971 Cleaves and Broussard1980 Rasmussen et al 1985 Bhattacharya and Walker1991 Li et al 2011 Olariu et al 2012) and in lacustrinebasins (eg Cretaceous Songliao Basin Lou et al 1999Triassic Ordos Basin Zou et al 2008) However com-
pared with the large number of investigations of deep-water deltas or deltas at the shelf edge (eg Carvajaland Steel 2009 Covault et al 2009 Dixon et al 2012)the number of shallow-water deltas described in an-cient deposits is very limited
Deltas represented by clinoform seismic faciesMitchum et al (1977) promote the use of external
shape and internal configuration onseismic profiles to interpret stratalconfiguration facies patterns and depo-sitional environments of progradingstratigraphic sequences In particulartheir recognition of sigmoid obliquecomplex and shingled clinoform seismicfacies (Figure 4) and the general geologicinterpretation of these facies establishesa foundation for stratigraphic evaluationof seismic clinoforms A sigmoid clino-form pattern (Figure 4a) refers to a rela-tively low-energy sedimentary regimean oblique facies (Figure 4b) would oc-cur in a relatively high-energy sedimen-tary regime A complex sigmoid-obliquemodel (Figure 4c) results from alternat-ing high- and low-energy sedimentaryregimes Whereas these three types ofclinoforms are associated with deep-water basins a shingled clinoform
configuration (Figure 4d) represents depositional unitsprograding into shallow waters
Berg (1982) further links different clinoform con-figurations to some distinctive delta types The sig-moid oblique and complex sigmoid-oblique patterns(Figure 4andash4c) are representative seismic facies of adeep-water fluvial-dominated delta The sigmoid seismicpattern is composed of continuous and S-shapedclinoforms (Figure 4a) Without toplapping sigmoid pat-terns usually occur in low-energy delta interlobe areaslacking sandy deposits The oblique pattern (Figure 4b)is characterized by clinoforms that terminate updip bytoplap and downdip by downlap that bound the deltaicsequence This pattern represents a high-energy deltawhere the sand-rich delta plain is coincident with theupper horizontal events (undaform) The seismic clino-form is equivalent to shale-prone prodelta facies The ab-sence of stacking of horizontal events in the delta plainsuggests sediment bypassing on a stable shelf The com-plex sigmoid-oblique pattern (Figure 4c) is a result ofalternate high-energy sandy deposition (oblique) andlow-energy shaly deposition (sigmoid) that occurred indelta-lobe shifting during delta system outbuildingThe shingled pattern (Figure 4d) appears to indicate awave-dominated delta in shallow water Developmentof a wave-dominated delta seems to require a stable shal-low depositional shelf Less studied and documentedtide-dominated deltas are difficult to identify using sim-ple seismic clinoform patterns
Table 1 Hmin in meters as a function of the predominant frequency ofthe seismic data and the velocity of prograding sediments Typicalindustry data are characterized by a predominant frequency from 20 to50 Hz
f (Hz) V frac14 2000m∕s
V frac14 3000m∕s
V frac14 4000m∕s
V frac14 5000m∕s
V frac14 6000m∕s
20 500 750 1000 1250 1500
25 400 600 800 1000 1200
30 333 500 667 833 1000
40 250 375 500 625 750
50 200 300 400 500 600
60 167 250 333 417 500
80 125 187 250 312 375
100 100 150 200 250 300
200 50 75 100 125 150
0 1200 km
BEIJINGPeoplersquos Republic
of China
0 500 km
48deg
46deg
44deg
50deg126deg 128deg 130deg
124deg122deg
Qiqihar
Harbin
Changchun
DaqingOilfieldStudy
area
SongliaoBasin
QAe1681
N
Figure 6 Cretaceous Songliao Basin of China showing thestudy area in the Qijia Depression near the Daqing Oilfield
SA38 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Limits of clinoform seismic faciesBarring any data quality issues related to acquisition
and processing our ability to use clinoform seismicstratigraphy to recognize progradational depositionalsequences is largely limited by seismic resolution
To visually identify a clinoform pattern within a seis-mic stratigraphic mapping unit one has to recognize atleast two seismic events with one offlapping the otherIn other words the unit has to be at least as thick as thewidth of two seismic events (one wavelength or cycle)in two-way traveltime We call the thickness of such aseismic stratigraphic mapping unit clinoform detectionlimit
Hmin frac14 1000∕f (1)
where f denotes the predominant frequency of the seis-mic data in hertz (Hz) and Hmin is the clinoform detec-tion limit in milliseconds (ms) The clinoform detection
limit in depth is related to the predominant frequency ofthe seismic data and the velocity of the prograding sedi-ments (Figure 5 Table 1)
Hmin frac14 V∕2f (2)
where V denotes velocity of the sediments in meters persecond (m∕s) and Hmin is the clinoform detection limitin meters (m) Most modern seismic data sets are char-acterized by a predominant frequency ranging from20 to 100 Hz corresponding to Hmin (in time) from10 to 50 ms In a typical clastic basin the velocity ofsandstones and shales is usually between 2000 and4000 m∕s resulting in a Hmin (in depth) of 10 to100 m in a carbonate formation rock velocity is signifi-cantly higher (mostly 5000 minus 6000 m∕s) and Hmin (indepth) increases sizably (25ndash150 m)
These simple calculations reveal that seismic clino-form recognition is reserved to thicker prograding
rsquoAA
G21
G42G41G32G31
G22
G12
SQ1SS1SS2
SS3
SS4
SS5
SS6
SQ2
SQ3
G11
Tra
velti
me
(ms)
T1
T2
a)Basinward
2 km2 km
b)
SQ1
SQ2
SQ3
T1
T2
Rel
ativ
e ge
olog
ic ti
me
a
b
c
SS1
SS2
SS3
SS4
SS5
SS6
G21
G42G41G32G31G22
G12G11
Third-orderseq boundary
SP DT High-ordersequence
Fault
fifth fourth third
fifth fourth third
- +
Amplitude
A
Arsquo
BBrsquo
QAe1682
2 km
1200
1300
1400
1500
1600
1700
Figure 7 A dip well-seismic section illustrat-ing the high-frequency depositional sequenceframework and internal nonclinoform reflec-tion pattern in the Cretaceous Qijia Depres-sion (modified from Zeng et al 2012) SeeFigure 7a for position (a) Traveltime sectionshowing wireline logs sequence definitionand well-seismic correlation (b) Wheeler-transformed section flattened in relativegeologic time for easy viewing of internalreflection characteristics Positions of stratalslices in Figure 10 are labeled a b and c SP frac14spontaneous potential log DT = sonic log
Interpretation August 2013 SA39
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
depositional sequences or the thicker part of a prograd-ing depositional sequence Sequences thinner thanHminnormally do not show as clinoforms on seismic profilesDepending on the current status of seismic data qualityin basins around the world a large number of shallow-water deltas would fall below Hmin because they devel-oped in water depths shallower than tens of meters
These shallow-water deltas are good candidates to bereflected as nonclinoform seismic patterns Accord-ingly the interpretation of deltas needs to go beyondthe recognition of seismic clinoforms Lacking visibleclinoforms shallow-water deltas would routinely gounrecognized by seismic interpreters Seismic faciesof those nonclinoform sequences are our major concernin following sections
Examples of seismic nonclinoform deltasIn this section three investigations are presented
as examples of seismic nonclinoform deltas Withoutvisible seismic clinoforms seismic geomorphologypatterns on amplitude stratal slices provide vital infor-mation for interpreting thin deltaic systems The pro-duction of stratal slices has followed the procedurediscussed in Zeng et al (1998a 1998b) Where availableconventional cores and wireline logs have been used tocalibrate the interpretations in these studies
Qijia depression Songliao Basin ChinaThe Songliao Basin of China is a large-scale
Mesozoic-Cenozoic lacustrine basin covering an areaof more than 250000 km2 (Figure 6) In lower throughupper Cretaceous strata postrift deposits as thick as3000 to 4000 m unconformably overlie synrift strataand extend beyond the fault blocks to cover the wholebasin (Feng et al 2010) Lacking true shelf breaks seis-mic clinoforms can be seen only along major delta axeswhere fluvial systems transported abundant sedimentto the deep part of the lake in the center of the basin
B B
+-
Amplitude2 km
50 m
s50
ms
QAe1683
50 m
s
a
b
c
Figure 8 Strike seismic section showing the internal reflec-tion pattern in the Cretaceous Qijia Depression The expectedmounded seismic configuration for a ldquonormalrdquo deltaic system(Figure 3b) does not exist The regional structural trend is cor-rected for a better view of internal reflection characteristicsPositions of stratal slices in Figure 10 are labeled a b and cSee Figure 7a for position
QAe1684
10 m
Del
ta fr
ont
Sha
llow
lake
Depth(m)
Limestone
Shale
Sandstone
sotohp eroCseicafbuSnoitces deroC
GR DT
a)
b)
c)
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2120
2133
a)
b)
c)
Figure 9 Description of a cored section in awell in the Qijia Depression showing Creta-ceous fluvial-dominated shallow-water deltadeposits Arrows denote upward-coarseninggrain-size trends (a) Shallow-lake Ostracodalimestone (b) trough-cross-stratified (arrow)fine-grained distributary-channel sandstone(c) medium-grained blocky sandstone withshale lag (arrow) on the scoured distributary-channel base Cores are oriented up (shal-lower) to the left
SA40 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(eg in the Daqing Oilfield area) Much of the deltaicsediment was deposited in very gentle slopes aroundthe basin margin in shallow waters lacking well-developed clinoforms
In the Qijia Depression (Figure 6) deltaic sedimentsconsist of gray and dark-gray mudstone interbeddedwith sandstone and siltstone A wireline-log-basedsequence-stratigraphic correlation (Figure 7a) revealedmultiple higher order sequences (G11 through SS1) inthree third-order sequences (SQ1 through SQ3) in theQingshankou Formation (Zeng et al 2012) In this22-km-long dip-oriented section thickness changesfrom updip to downdip are minor revealing a very gen-tle slope at the time of deposition Each of the higherorder sequences has an average thickness of approxi-mately 40 m which is composed of a relative lowstandsystems tract (LST) at the bottom and a relative high-stand systems tract (HST) at the top with roughly equalthickness (20 m)
A Wheeler-transformed equivalent of Figure 7a isrealized with stratal slicing processing (Figure 7b)which shows a good correlation between well-baseddepositional sequences and seismic events The 3Dseismic data have a frequency range of 10 to 80 Hzand a dominant frequency of 50 Hz In this formationaverage velocity is 4000 m∕s and the calculated Hminis 40 m (Table 1) This doubles the Hmin in this forma-tion for seismic imaging of clinoform complexes ineither LST or HST As a result seismic clinoformsare not imaged Instead these seismic events can beclassified as subparallel to discontinuous variable-amplitude seismic facies Each pair of seismic events(peak at bottom and trough at top) in each of thehigh-frequency sequences roughly represents a high-frequency sequence composed of a relative LST at thebottom and a relative HST at the top A strike seismicsection (Figure 8) shows a seismic facies distributionsimilar to that in the dip section (Figure 7) and fails
Fault- +
Amplitude
Shoreline Channellobe
Deltaplain
Deltafront
Prodeltalake
Direction ofprogradation
2 km2 km2 km
QAe1685
a)
c)
e)
b)
d)
f)
Figure 10 Three amplitude stratal slices (ac and e) at three high-frequency sequences(G31 G41 and SS2 respectively in Figure 7band labeled as a b and c in Figures 7b and 8)These slices interpreted as shallow-water del-tas are shown in (b d and f) respectivelyShorelines interpreted in (d and f) refer toposition of the successive shorelines duringprogradation
Interpretation August 2013 SA41
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
to reveal any seismic reflection configuration thatresembles the mound geometry associated with typicalprograding delta clinoforms (Figure 3b)
Lithology grain-size trend and sedimentary struc-ture were observed in conventional cores providingmore direct evidence for classifying depositional faciesBy describing more than 1300 m of core in 11 wells inthe area we recognized that most subfacies in the coreare related to fluvial-dominated deltaic deposition Forexample in a long cored section (Figure 9) a typicalfacies cycle (from bottom to top) includes gray shaleand thin limestone (Figure 9a) representing shallow-lake deposition trough-cross-stratified fine-grainedsandstone (Figure 9b) from the distributary channeland medium-grained blocky sandstone with shale-clastlag (Figure 9c) on the scoured distributary-channelbase in the delta front There are abundant ostracodfossils (eg Cypridea Candona Mongolocypris andZiziphocypris) identified in the limestones andshales all indicative of a shallow-water environmentRanging from 4- to 15-m thick the upward-coarseningsequences are a result of progradational processes ina shallow-water deltaic system (eg Olariu and Bhatta-charya 2006)
A set of stratal slices was constructed in the intervalbetween reference events T1 and T2 from stacked andmigrated data (Figure 7a) All the stratal slices roughlyfollow individual seismic events that are parallel toone another Selected slices (Figure 10a 10c and10e) represent three thin LST deltaic depositional sys-tems in high-order sequences The most striking seismicgeomorphologic features in these stratal slices are nu-merous channel patterns and associated amplitudeanomalies of different shapes representing variousdeltaic environments (Figure 10b 10d and 10f)Differences in the facies patterns reflect relative mar-gin-to-basin positions in the gentle slope of a postriftlacustrine basin During deposition of the high-frequency sequence SS2 (Figure 10a and 10b) the lakewas at its maximum depth and extent and the studyarea was a delta front Distributary channels extendedfar into the basin and were rarely exposed before burialA fringing sandy delta front was lacking Later duringdeposition of the high-frequency sequences G41(Figure 10c and 10d) and G31 (Figure 10e and 10f)the lake diminished in area after repeated deltaic-deposition episodes The study area is located in theshoreline area which has a narrower delta-front zoneThe deltaic system prograded on a smaller scale withdeltaic lobes forming one in front of another attachedto shorter distributary channels which terminated atthe shoreline at the time of deposition Multiple shore-line positions can be determined on the basis of channelterminations (Figure 10c and 10d) or amplitude zoning(Figure 10e and 10f) showing a general direction ofdeltaic progradation
Miocene deltas at the Gulf of MexicoLouisiana United States
Starfak and Tiger Shoal fields of offshore LouisianaUnited States (Figure 11) lie along the western periph-ery of the ancestral Mississippi River area Located inthe Oligocene-Miocene Detachment Province of thenorth Gulf Coast continental margin (Diegel et al1995) Miocene deposits are largely controlled bydown-to-the-basin listric growth faults that sole on aregional detachment zone above the Oligocene sectionSalt tectonics and growth faulting resulted in a greatthickness of deltaic and other on-shelf sediments duringa period of high sedimentation rates Interpreted depo-sitional environments include lowstand progradingwedge slope fan and basin-floor fan beyond the shelfedge incised valley highstand delta and transgressivefacies and coastal plain coastal delta and inner-shelfmarine deposits in the coastal area (Hentz and Zeng2003)
All these Miocene depositional systems are com-posed of interbedded sandstone and shale units withsandstones varying widely in thickness and rangingfrom 1 to 40 m Although the study area is situatedin a passive continental margin a representative dipseismic section across the area (Figure 12) demon-strates mostly parallel to divergent seismic facies
TEXAS
LOUISIANA
MISSISSIPPI
3D surveysField
N
VERMILIONAREA
SOUTH MARSHISLAND AREA
North LightHouse Point
TigerShoal
Starfak C
LOUISIANA
MARSH ISLAND
C
A
A
0
0
5 mi
8 km
B
B
LightHousePoint
Trinity Shoal
Amber Complex
Mound Point
Fig 13
QAe1686
Figure 11 Location of Starfak and Tiger Shoal fields 3Dseismic surveys and wells in the Louisiana Gulf Coast
SA42 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(Zou et al 2008) in lacustrine basins Several authorsinvestigate many ancient subsurface examples of shal-low-water deltas deposited in shallow intracratonic sea-ways (eg Busch 1959 1971 Cleaves and Broussard1980 Rasmussen et al 1985 Bhattacharya and Walker1991 Li et al 2011 Olariu et al 2012) and in lacustrinebasins (eg Cretaceous Songliao Basin Lou et al 1999Triassic Ordos Basin Zou et al 2008) However com-
pared with the large number of investigations of deep-water deltas or deltas at the shelf edge (eg Carvajaland Steel 2009 Covault et al 2009 Dixon et al 2012)the number of shallow-water deltas described in an-cient deposits is very limited
Deltas represented by clinoform seismic faciesMitchum et al (1977) promote the use of external
shape and internal configuration onseismic profiles to interpret stratalconfiguration facies patterns and depo-sitional environments of progradingstratigraphic sequences In particulartheir recognition of sigmoid obliquecomplex and shingled clinoform seismicfacies (Figure 4) and the general geologicinterpretation of these facies establishesa foundation for stratigraphic evaluationof seismic clinoforms A sigmoid clino-form pattern (Figure 4a) refers to a rela-tively low-energy sedimentary regimean oblique facies (Figure 4b) would oc-cur in a relatively high-energy sedimen-tary regime A complex sigmoid-obliquemodel (Figure 4c) results from alternat-ing high- and low-energy sedimentaryregimes Whereas these three types ofclinoforms are associated with deep-water basins a shingled clinoform
configuration (Figure 4d) represents depositional unitsprograding into shallow waters
Berg (1982) further links different clinoform con-figurations to some distinctive delta types The sig-moid oblique and complex sigmoid-oblique patterns(Figure 4andash4c) are representative seismic facies of adeep-water fluvial-dominated delta The sigmoid seismicpattern is composed of continuous and S-shapedclinoforms (Figure 4a) Without toplapping sigmoid pat-terns usually occur in low-energy delta interlobe areaslacking sandy deposits The oblique pattern (Figure 4b)is characterized by clinoforms that terminate updip bytoplap and downdip by downlap that bound the deltaicsequence This pattern represents a high-energy deltawhere the sand-rich delta plain is coincident with theupper horizontal events (undaform) The seismic clino-form is equivalent to shale-prone prodelta facies The ab-sence of stacking of horizontal events in the delta plainsuggests sediment bypassing on a stable shelf The com-plex sigmoid-oblique pattern (Figure 4c) is a result ofalternate high-energy sandy deposition (oblique) andlow-energy shaly deposition (sigmoid) that occurred indelta-lobe shifting during delta system outbuildingThe shingled pattern (Figure 4d) appears to indicate awave-dominated delta in shallow water Developmentof a wave-dominated delta seems to require a stable shal-low depositional shelf Less studied and documentedtide-dominated deltas are difficult to identify using sim-ple seismic clinoform patterns
Table 1 Hmin in meters as a function of the predominant frequency ofthe seismic data and the velocity of prograding sediments Typicalindustry data are characterized by a predominant frequency from 20 to50 Hz
f (Hz) V frac14 2000m∕s
V frac14 3000m∕s
V frac14 4000m∕s
V frac14 5000m∕s
V frac14 6000m∕s
20 500 750 1000 1250 1500
25 400 600 800 1000 1200
30 333 500 667 833 1000
40 250 375 500 625 750
50 200 300 400 500 600
60 167 250 333 417 500
80 125 187 250 312 375
100 100 150 200 250 300
200 50 75 100 125 150
0 1200 km
BEIJINGPeoplersquos Republic
of China
0 500 km
48deg
46deg
44deg
50deg126deg 128deg 130deg
124deg122deg
Qiqihar
Harbin
Changchun
DaqingOilfieldStudy
area
SongliaoBasin
QAe1681
N
Figure 6 Cretaceous Songliao Basin of China showing thestudy area in the Qijia Depression near the Daqing Oilfield
SA38 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Limits of clinoform seismic faciesBarring any data quality issues related to acquisition
and processing our ability to use clinoform seismicstratigraphy to recognize progradational depositionalsequences is largely limited by seismic resolution
To visually identify a clinoform pattern within a seis-mic stratigraphic mapping unit one has to recognize atleast two seismic events with one offlapping the otherIn other words the unit has to be at least as thick as thewidth of two seismic events (one wavelength or cycle)in two-way traveltime We call the thickness of such aseismic stratigraphic mapping unit clinoform detectionlimit
Hmin frac14 1000∕f (1)
where f denotes the predominant frequency of the seis-mic data in hertz (Hz) and Hmin is the clinoform detec-tion limit in milliseconds (ms) The clinoform detection
limit in depth is related to the predominant frequency ofthe seismic data and the velocity of the prograding sedi-ments (Figure 5 Table 1)
Hmin frac14 V∕2f (2)
where V denotes velocity of the sediments in meters persecond (m∕s) and Hmin is the clinoform detection limitin meters (m) Most modern seismic data sets are char-acterized by a predominant frequency ranging from20 to 100 Hz corresponding to Hmin (in time) from10 to 50 ms In a typical clastic basin the velocity ofsandstones and shales is usually between 2000 and4000 m∕s resulting in a Hmin (in depth) of 10 to100 m in a carbonate formation rock velocity is signifi-cantly higher (mostly 5000 minus 6000 m∕s) and Hmin (indepth) increases sizably (25ndash150 m)
These simple calculations reveal that seismic clino-form recognition is reserved to thicker prograding
rsquoAA
G21
G42G41G32G31
G22
G12
SQ1SS1SS2
SS3
SS4
SS5
SS6
SQ2
SQ3
G11
Tra
velti
me
(ms)
T1
T2
a)Basinward
2 km2 km
b)
SQ1
SQ2
SQ3
T1
T2
Rel
ativ
e ge
olog
ic ti
me
a
b
c
SS1
SS2
SS3
SS4
SS5
SS6
G21
G42G41G32G31G22
G12G11
Third-orderseq boundary
SP DT High-ordersequence
Fault
fifth fourth third
fifth fourth third
- +
Amplitude
A
Arsquo
BBrsquo
QAe1682
2 km
1200
1300
1400
1500
1600
1700
Figure 7 A dip well-seismic section illustrat-ing the high-frequency depositional sequenceframework and internal nonclinoform reflec-tion pattern in the Cretaceous Qijia Depres-sion (modified from Zeng et al 2012) SeeFigure 7a for position (a) Traveltime sectionshowing wireline logs sequence definitionand well-seismic correlation (b) Wheeler-transformed section flattened in relativegeologic time for easy viewing of internalreflection characteristics Positions of stratalslices in Figure 10 are labeled a b and c SP frac14spontaneous potential log DT = sonic log
Interpretation August 2013 SA39
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
depositional sequences or the thicker part of a prograd-ing depositional sequence Sequences thinner thanHminnormally do not show as clinoforms on seismic profilesDepending on the current status of seismic data qualityin basins around the world a large number of shallow-water deltas would fall below Hmin because they devel-oped in water depths shallower than tens of meters
These shallow-water deltas are good candidates to bereflected as nonclinoform seismic patterns Accord-ingly the interpretation of deltas needs to go beyondthe recognition of seismic clinoforms Lacking visibleclinoforms shallow-water deltas would routinely gounrecognized by seismic interpreters Seismic faciesof those nonclinoform sequences are our major concernin following sections
Examples of seismic nonclinoform deltasIn this section three investigations are presented
as examples of seismic nonclinoform deltas Withoutvisible seismic clinoforms seismic geomorphologypatterns on amplitude stratal slices provide vital infor-mation for interpreting thin deltaic systems The pro-duction of stratal slices has followed the procedurediscussed in Zeng et al (1998a 1998b) Where availableconventional cores and wireline logs have been used tocalibrate the interpretations in these studies
Qijia depression Songliao Basin ChinaThe Songliao Basin of China is a large-scale
Mesozoic-Cenozoic lacustrine basin covering an areaof more than 250000 km2 (Figure 6) In lower throughupper Cretaceous strata postrift deposits as thick as3000 to 4000 m unconformably overlie synrift strataand extend beyond the fault blocks to cover the wholebasin (Feng et al 2010) Lacking true shelf breaks seis-mic clinoforms can be seen only along major delta axeswhere fluvial systems transported abundant sedimentto the deep part of the lake in the center of the basin
B B
+-
Amplitude2 km
50 m
s50
ms
QAe1683
50 m
s
a
b
c
Figure 8 Strike seismic section showing the internal reflec-tion pattern in the Cretaceous Qijia Depression The expectedmounded seismic configuration for a ldquonormalrdquo deltaic system(Figure 3b) does not exist The regional structural trend is cor-rected for a better view of internal reflection characteristicsPositions of stratal slices in Figure 10 are labeled a b and cSee Figure 7a for position
QAe1684
10 m
Del
ta fr
ont
Sha
llow
lake
Depth(m)
Limestone
Shale
Sandstone
sotohp eroCseicafbuSnoitces deroC
GR DT
a)
b)
c)
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2120
2133
a)
b)
c)
Figure 9 Description of a cored section in awell in the Qijia Depression showing Creta-ceous fluvial-dominated shallow-water deltadeposits Arrows denote upward-coarseninggrain-size trends (a) Shallow-lake Ostracodalimestone (b) trough-cross-stratified (arrow)fine-grained distributary-channel sandstone(c) medium-grained blocky sandstone withshale lag (arrow) on the scoured distributary-channel base Cores are oriented up (shal-lower) to the left
SA40 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(eg in the Daqing Oilfield area) Much of the deltaicsediment was deposited in very gentle slopes aroundthe basin margin in shallow waters lacking well-developed clinoforms
In the Qijia Depression (Figure 6) deltaic sedimentsconsist of gray and dark-gray mudstone interbeddedwith sandstone and siltstone A wireline-log-basedsequence-stratigraphic correlation (Figure 7a) revealedmultiple higher order sequences (G11 through SS1) inthree third-order sequences (SQ1 through SQ3) in theQingshankou Formation (Zeng et al 2012) In this22-km-long dip-oriented section thickness changesfrom updip to downdip are minor revealing a very gen-tle slope at the time of deposition Each of the higherorder sequences has an average thickness of approxi-mately 40 m which is composed of a relative lowstandsystems tract (LST) at the bottom and a relative high-stand systems tract (HST) at the top with roughly equalthickness (20 m)
A Wheeler-transformed equivalent of Figure 7a isrealized with stratal slicing processing (Figure 7b)which shows a good correlation between well-baseddepositional sequences and seismic events The 3Dseismic data have a frequency range of 10 to 80 Hzand a dominant frequency of 50 Hz In this formationaverage velocity is 4000 m∕s and the calculated Hminis 40 m (Table 1) This doubles the Hmin in this forma-tion for seismic imaging of clinoform complexes ineither LST or HST As a result seismic clinoformsare not imaged Instead these seismic events can beclassified as subparallel to discontinuous variable-amplitude seismic facies Each pair of seismic events(peak at bottom and trough at top) in each of thehigh-frequency sequences roughly represents a high-frequency sequence composed of a relative LST at thebottom and a relative HST at the top A strike seismicsection (Figure 8) shows a seismic facies distributionsimilar to that in the dip section (Figure 7) and fails
Fault- +
Amplitude
Shoreline Channellobe
Deltaplain
Deltafront
Prodeltalake
Direction ofprogradation
2 km2 km2 km
QAe1685
a)
c)
e)
b)
d)
f)
Figure 10 Three amplitude stratal slices (ac and e) at three high-frequency sequences(G31 G41 and SS2 respectively in Figure 7band labeled as a b and c in Figures 7b and 8)These slices interpreted as shallow-water del-tas are shown in (b d and f) respectivelyShorelines interpreted in (d and f) refer toposition of the successive shorelines duringprogradation
Interpretation August 2013 SA41
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
to reveal any seismic reflection configuration thatresembles the mound geometry associated with typicalprograding delta clinoforms (Figure 3b)
Lithology grain-size trend and sedimentary struc-ture were observed in conventional cores providingmore direct evidence for classifying depositional faciesBy describing more than 1300 m of core in 11 wells inthe area we recognized that most subfacies in the coreare related to fluvial-dominated deltaic deposition Forexample in a long cored section (Figure 9) a typicalfacies cycle (from bottom to top) includes gray shaleand thin limestone (Figure 9a) representing shallow-lake deposition trough-cross-stratified fine-grainedsandstone (Figure 9b) from the distributary channeland medium-grained blocky sandstone with shale-clastlag (Figure 9c) on the scoured distributary-channelbase in the delta front There are abundant ostracodfossils (eg Cypridea Candona Mongolocypris andZiziphocypris) identified in the limestones andshales all indicative of a shallow-water environmentRanging from 4- to 15-m thick the upward-coarseningsequences are a result of progradational processes ina shallow-water deltaic system (eg Olariu and Bhatta-charya 2006)
A set of stratal slices was constructed in the intervalbetween reference events T1 and T2 from stacked andmigrated data (Figure 7a) All the stratal slices roughlyfollow individual seismic events that are parallel toone another Selected slices (Figure 10a 10c and10e) represent three thin LST deltaic depositional sys-tems in high-order sequences The most striking seismicgeomorphologic features in these stratal slices are nu-merous channel patterns and associated amplitudeanomalies of different shapes representing variousdeltaic environments (Figure 10b 10d and 10f)Differences in the facies patterns reflect relative mar-gin-to-basin positions in the gentle slope of a postriftlacustrine basin During deposition of the high-frequency sequence SS2 (Figure 10a and 10b) the lakewas at its maximum depth and extent and the studyarea was a delta front Distributary channels extendedfar into the basin and were rarely exposed before burialA fringing sandy delta front was lacking Later duringdeposition of the high-frequency sequences G41(Figure 10c and 10d) and G31 (Figure 10e and 10f)the lake diminished in area after repeated deltaic-deposition episodes The study area is located in theshoreline area which has a narrower delta-front zoneThe deltaic system prograded on a smaller scale withdeltaic lobes forming one in front of another attachedto shorter distributary channels which terminated atthe shoreline at the time of deposition Multiple shore-line positions can be determined on the basis of channelterminations (Figure 10c and 10d) or amplitude zoning(Figure 10e and 10f) showing a general direction ofdeltaic progradation
Miocene deltas at the Gulf of MexicoLouisiana United States
Starfak and Tiger Shoal fields of offshore LouisianaUnited States (Figure 11) lie along the western periph-ery of the ancestral Mississippi River area Located inthe Oligocene-Miocene Detachment Province of thenorth Gulf Coast continental margin (Diegel et al1995) Miocene deposits are largely controlled bydown-to-the-basin listric growth faults that sole on aregional detachment zone above the Oligocene sectionSalt tectonics and growth faulting resulted in a greatthickness of deltaic and other on-shelf sediments duringa period of high sedimentation rates Interpreted depo-sitional environments include lowstand progradingwedge slope fan and basin-floor fan beyond the shelfedge incised valley highstand delta and transgressivefacies and coastal plain coastal delta and inner-shelfmarine deposits in the coastal area (Hentz and Zeng2003)
All these Miocene depositional systems are com-posed of interbedded sandstone and shale units withsandstones varying widely in thickness and rangingfrom 1 to 40 m Although the study area is situatedin a passive continental margin a representative dipseismic section across the area (Figure 12) demon-strates mostly parallel to divergent seismic facies
TEXAS
LOUISIANA
MISSISSIPPI
3D surveysField
N
VERMILIONAREA
SOUTH MARSHISLAND AREA
North LightHouse Point
TigerShoal
Starfak C
LOUISIANA
MARSH ISLAND
C
A
A
0
0
5 mi
8 km
B
B
LightHousePoint
Trinity Shoal
Amber Complex
Mound Point
Fig 13
QAe1686
Figure 11 Location of Starfak and Tiger Shoal fields 3Dseismic surveys and wells in the Louisiana Gulf Coast
SA42 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Limits of clinoform seismic faciesBarring any data quality issues related to acquisition
and processing our ability to use clinoform seismicstratigraphy to recognize progradational depositionalsequences is largely limited by seismic resolution
To visually identify a clinoform pattern within a seis-mic stratigraphic mapping unit one has to recognize atleast two seismic events with one offlapping the otherIn other words the unit has to be at least as thick as thewidth of two seismic events (one wavelength or cycle)in two-way traveltime We call the thickness of such aseismic stratigraphic mapping unit clinoform detectionlimit
Hmin frac14 1000∕f (1)
where f denotes the predominant frequency of the seis-mic data in hertz (Hz) and Hmin is the clinoform detec-tion limit in milliseconds (ms) The clinoform detection
limit in depth is related to the predominant frequency ofthe seismic data and the velocity of the prograding sedi-ments (Figure 5 Table 1)
Hmin frac14 V∕2f (2)
where V denotes velocity of the sediments in meters persecond (m∕s) and Hmin is the clinoform detection limitin meters (m) Most modern seismic data sets are char-acterized by a predominant frequency ranging from20 to 100 Hz corresponding to Hmin (in time) from10 to 50 ms In a typical clastic basin the velocity ofsandstones and shales is usually between 2000 and4000 m∕s resulting in a Hmin (in depth) of 10 to100 m in a carbonate formation rock velocity is signifi-cantly higher (mostly 5000 minus 6000 m∕s) and Hmin (indepth) increases sizably (25ndash150 m)
These simple calculations reveal that seismic clino-form recognition is reserved to thicker prograding
rsquoAA
G21
G42G41G32G31
G22
G12
SQ1SS1SS2
SS3
SS4
SS5
SS6
SQ2
SQ3
G11
Tra
velti
me
(ms)
T1
T2
a)Basinward
2 km2 km
b)
SQ1
SQ2
SQ3
T1
T2
Rel
ativ
e ge
olog
ic ti
me
a
b
c
SS1
SS2
SS3
SS4
SS5
SS6
G21
G42G41G32G31G22
G12G11
Third-orderseq boundary
SP DT High-ordersequence
Fault
fifth fourth third
fifth fourth third
- +
Amplitude
A
Arsquo
BBrsquo
QAe1682
2 km
1200
1300
1400
1500
1600
1700
Figure 7 A dip well-seismic section illustrat-ing the high-frequency depositional sequenceframework and internal nonclinoform reflec-tion pattern in the Cretaceous Qijia Depres-sion (modified from Zeng et al 2012) SeeFigure 7a for position (a) Traveltime sectionshowing wireline logs sequence definitionand well-seismic correlation (b) Wheeler-transformed section flattened in relativegeologic time for easy viewing of internalreflection characteristics Positions of stratalslices in Figure 10 are labeled a b and c SP frac14spontaneous potential log DT = sonic log
Interpretation August 2013 SA39
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
depositional sequences or the thicker part of a prograd-ing depositional sequence Sequences thinner thanHminnormally do not show as clinoforms on seismic profilesDepending on the current status of seismic data qualityin basins around the world a large number of shallow-water deltas would fall below Hmin because they devel-oped in water depths shallower than tens of meters
These shallow-water deltas are good candidates to bereflected as nonclinoform seismic patterns Accord-ingly the interpretation of deltas needs to go beyondthe recognition of seismic clinoforms Lacking visibleclinoforms shallow-water deltas would routinely gounrecognized by seismic interpreters Seismic faciesof those nonclinoform sequences are our major concernin following sections
Examples of seismic nonclinoform deltasIn this section three investigations are presented
as examples of seismic nonclinoform deltas Withoutvisible seismic clinoforms seismic geomorphologypatterns on amplitude stratal slices provide vital infor-mation for interpreting thin deltaic systems The pro-duction of stratal slices has followed the procedurediscussed in Zeng et al (1998a 1998b) Where availableconventional cores and wireline logs have been used tocalibrate the interpretations in these studies
Qijia depression Songliao Basin ChinaThe Songliao Basin of China is a large-scale
Mesozoic-Cenozoic lacustrine basin covering an areaof more than 250000 km2 (Figure 6) In lower throughupper Cretaceous strata postrift deposits as thick as3000 to 4000 m unconformably overlie synrift strataand extend beyond the fault blocks to cover the wholebasin (Feng et al 2010) Lacking true shelf breaks seis-mic clinoforms can be seen only along major delta axeswhere fluvial systems transported abundant sedimentto the deep part of the lake in the center of the basin
B B
+-
Amplitude2 km
50 m
s50
ms
QAe1683
50 m
s
a
b
c
Figure 8 Strike seismic section showing the internal reflec-tion pattern in the Cretaceous Qijia Depression The expectedmounded seismic configuration for a ldquonormalrdquo deltaic system(Figure 3b) does not exist The regional structural trend is cor-rected for a better view of internal reflection characteristicsPositions of stratal slices in Figure 10 are labeled a b and cSee Figure 7a for position
QAe1684
10 m
Del
ta fr
ont
Sha
llow
lake
Depth(m)
Limestone
Shale
Sandstone
sotohp eroCseicafbuSnoitces deroC
GR DT
a)
b)
c)
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2120
2133
a)
b)
c)
Figure 9 Description of a cored section in awell in the Qijia Depression showing Creta-ceous fluvial-dominated shallow-water deltadeposits Arrows denote upward-coarseninggrain-size trends (a) Shallow-lake Ostracodalimestone (b) trough-cross-stratified (arrow)fine-grained distributary-channel sandstone(c) medium-grained blocky sandstone withshale lag (arrow) on the scoured distributary-channel base Cores are oriented up (shal-lower) to the left
SA40 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(eg in the Daqing Oilfield area) Much of the deltaicsediment was deposited in very gentle slopes aroundthe basin margin in shallow waters lacking well-developed clinoforms
In the Qijia Depression (Figure 6) deltaic sedimentsconsist of gray and dark-gray mudstone interbeddedwith sandstone and siltstone A wireline-log-basedsequence-stratigraphic correlation (Figure 7a) revealedmultiple higher order sequences (G11 through SS1) inthree third-order sequences (SQ1 through SQ3) in theQingshankou Formation (Zeng et al 2012) In this22-km-long dip-oriented section thickness changesfrom updip to downdip are minor revealing a very gen-tle slope at the time of deposition Each of the higherorder sequences has an average thickness of approxi-mately 40 m which is composed of a relative lowstandsystems tract (LST) at the bottom and a relative high-stand systems tract (HST) at the top with roughly equalthickness (20 m)
A Wheeler-transformed equivalent of Figure 7a isrealized with stratal slicing processing (Figure 7b)which shows a good correlation between well-baseddepositional sequences and seismic events The 3Dseismic data have a frequency range of 10 to 80 Hzand a dominant frequency of 50 Hz In this formationaverage velocity is 4000 m∕s and the calculated Hminis 40 m (Table 1) This doubles the Hmin in this forma-tion for seismic imaging of clinoform complexes ineither LST or HST As a result seismic clinoformsare not imaged Instead these seismic events can beclassified as subparallel to discontinuous variable-amplitude seismic facies Each pair of seismic events(peak at bottom and trough at top) in each of thehigh-frequency sequences roughly represents a high-frequency sequence composed of a relative LST at thebottom and a relative HST at the top A strike seismicsection (Figure 8) shows a seismic facies distributionsimilar to that in the dip section (Figure 7) and fails
Fault- +
Amplitude
Shoreline Channellobe
Deltaplain
Deltafront
Prodeltalake
Direction ofprogradation
2 km2 km2 km
QAe1685
a)
c)
e)
b)
d)
f)
Figure 10 Three amplitude stratal slices (ac and e) at three high-frequency sequences(G31 G41 and SS2 respectively in Figure 7band labeled as a b and c in Figures 7b and 8)These slices interpreted as shallow-water del-tas are shown in (b d and f) respectivelyShorelines interpreted in (d and f) refer toposition of the successive shorelines duringprogradation
Interpretation August 2013 SA41
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
to reveal any seismic reflection configuration thatresembles the mound geometry associated with typicalprograding delta clinoforms (Figure 3b)
Lithology grain-size trend and sedimentary struc-ture were observed in conventional cores providingmore direct evidence for classifying depositional faciesBy describing more than 1300 m of core in 11 wells inthe area we recognized that most subfacies in the coreare related to fluvial-dominated deltaic deposition Forexample in a long cored section (Figure 9) a typicalfacies cycle (from bottom to top) includes gray shaleand thin limestone (Figure 9a) representing shallow-lake deposition trough-cross-stratified fine-grainedsandstone (Figure 9b) from the distributary channeland medium-grained blocky sandstone with shale-clastlag (Figure 9c) on the scoured distributary-channelbase in the delta front There are abundant ostracodfossils (eg Cypridea Candona Mongolocypris andZiziphocypris) identified in the limestones andshales all indicative of a shallow-water environmentRanging from 4- to 15-m thick the upward-coarseningsequences are a result of progradational processes ina shallow-water deltaic system (eg Olariu and Bhatta-charya 2006)
A set of stratal slices was constructed in the intervalbetween reference events T1 and T2 from stacked andmigrated data (Figure 7a) All the stratal slices roughlyfollow individual seismic events that are parallel toone another Selected slices (Figure 10a 10c and10e) represent three thin LST deltaic depositional sys-tems in high-order sequences The most striking seismicgeomorphologic features in these stratal slices are nu-merous channel patterns and associated amplitudeanomalies of different shapes representing variousdeltaic environments (Figure 10b 10d and 10f)Differences in the facies patterns reflect relative mar-gin-to-basin positions in the gentle slope of a postriftlacustrine basin During deposition of the high-frequency sequence SS2 (Figure 10a and 10b) the lakewas at its maximum depth and extent and the studyarea was a delta front Distributary channels extendedfar into the basin and were rarely exposed before burialA fringing sandy delta front was lacking Later duringdeposition of the high-frequency sequences G41(Figure 10c and 10d) and G31 (Figure 10e and 10f)the lake diminished in area after repeated deltaic-deposition episodes The study area is located in theshoreline area which has a narrower delta-front zoneThe deltaic system prograded on a smaller scale withdeltaic lobes forming one in front of another attachedto shorter distributary channels which terminated atthe shoreline at the time of deposition Multiple shore-line positions can be determined on the basis of channelterminations (Figure 10c and 10d) or amplitude zoning(Figure 10e and 10f) showing a general direction ofdeltaic progradation
Miocene deltas at the Gulf of MexicoLouisiana United States
Starfak and Tiger Shoal fields of offshore LouisianaUnited States (Figure 11) lie along the western periph-ery of the ancestral Mississippi River area Located inthe Oligocene-Miocene Detachment Province of thenorth Gulf Coast continental margin (Diegel et al1995) Miocene deposits are largely controlled bydown-to-the-basin listric growth faults that sole on aregional detachment zone above the Oligocene sectionSalt tectonics and growth faulting resulted in a greatthickness of deltaic and other on-shelf sediments duringa period of high sedimentation rates Interpreted depo-sitional environments include lowstand progradingwedge slope fan and basin-floor fan beyond the shelfedge incised valley highstand delta and transgressivefacies and coastal plain coastal delta and inner-shelfmarine deposits in the coastal area (Hentz and Zeng2003)
All these Miocene depositional systems are com-posed of interbedded sandstone and shale units withsandstones varying widely in thickness and rangingfrom 1 to 40 m Although the study area is situatedin a passive continental margin a representative dipseismic section across the area (Figure 12) demon-strates mostly parallel to divergent seismic facies
TEXAS
LOUISIANA
MISSISSIPPI
3D surveysField
N
VERMILIONAREA
SOUTH MARSHISLAND AREA
North LightHouse Point
TigerShoal
Starfak C
LOUISIANA
MARSH ISLAND
C
A
A
0
0
5 mi
8 km
B
B
LightHousePoint
Trinity Shoal
Amber Complex
Mound Point
Fig 13
QAe1686
Figure 11 Location of Starfak and Tiger Shoal fields 3Dseismic surveys and wells in the Louisiana Gulf Coast
SA42 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
depositional sequences or the thicker part of a prograd-ing depositional sequence Sequences thinner thanHminnormally do not show as clinoforms on seismic profilesDepending on the current status of seismic data qualityin basins around the world a large number of shallow-water deltas would fall below Hmin because they devel-oped in water depths shallower than tens of meters
These shallow-water deltas are good candidates to bereflected as nonclinoform seismic patterns Accord-ingly the interpretation of deltas needs to go beyondthe recognition of seismic clinoforms Lacking visibleclinoforms shallow-water deltas would routinely gounrecognized by seismic interpreters Seismic faciesof those nonclinoform sequences are our major concernin following sections
Examples of seismic nonclinoform deltasIn this section three investigations are presented
as examples of seismic nonclinoform deltas Withoutvisible seismic clinoforms seismic geomorphologypatterns on amplitude stratal slices provide vital infor-mation for interpreting thin deltaic systems The pro-duction of stratal slices has followed the procedurediscussed in Zeng et al (1998a 1998b) Where availableconventional cores and wireline logs have been used tocalibrate the interpretations in these studies
Qijia depression Songliao Basin ChinaThe Songliao Basin of China is a large-scale
Mesozoic-Cenozoic lacustrine basin covering an areaof more than 250000 km2 (Figure 6) In lower throughupper Cretaceous strata postrift deposits as thick as3000 to 4000 m unconformably overlie synrift strataand extend beyond the fault blocks to cover the wholebasin (Feng et al 2010) Lacking true shelf breaks seis-mic clinoforms can be seen only along major delta axeswhere fluvial systems transported abundant sedimentto the deep part of the lake in the center of the basin
B B
+-
Amplitude2 km
50 m
s50
ms
QAe1683
50 m
s
a
b
c
Figure 8 Strike seismic section showing the internal reflec-tion pattern in the Cretaceous Qijia Depression The expectedmounded seismic configuration for a ldquonormalrdquo deltaic system(Figure 3b) does not exist The regional structural trend is cor-rected for a better view of internal reflection characteristicsPositions of stratal slices in Figure 10 are labeled a b and cSee Figure 7a for position
QAe1684
10 m
Del
ta fr
ont
Sha
llow
lake
Depth(m)
Limestone
Shale
Sandstone
sotohp eroCseicafbuSnoitces deroC
GR DT
a)
b)
c)
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2120
2133
a)
b)
c)
Figure 9 Description of a cored section in awell in the Qijia Depression showing Creta-ceous fluvial-dominated shallow-water deltadeposits Arrows denote upward-coarseninggrain-size trends (a) Shallow-lake Ostracodalimestone (b) trough-cross-stratified (arrow)fine-grained distributary-channel sandstone(c) medium-grained blocky sandstone withshale lag (arrow) on the scoured distributary-channel base Cores are oriented up (shal-lower) to the left
SA40 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(eg in the Daqing Oilfield area) Much of the deltaicsediment was deposited in very gentle slopes aroundthe basin margin in shallow waters lacking well-developed clinoforms
In the Qijia Depression (Figure 6) deltaic sedimentsconsist of gray and dark-gray mudstone interbeddedwith sandstone and siltstone A wireline-log-basedsequence-stratigraphic correlation (Figure 7a) revealedmultiple higher order sequences (G11 through SS1) inthree third-order sequences (SQ1 through SQ3) in theQingshankou Formation (Zeng et al 2012) In this22-km-long dip-oriented section thickness changesfrom updip to downdip are minor revealing a very gen-tle slope at the time of deposition Each of the higherorder sequences has an average thickness of approxi-mately 40 m which is composed of a relative lowstandsystems tract (LST) at the bottom and a relative high-stand systems tract (HST) at the top with roughly equalthickness (20 m)
A Wheeler-transformed equivalent of Figure 7a isrealized with stratal slicing processing (Figure 7b)which shows a good correlation between well-baseddepositional sequences and seismic events The 3Dseismic data have a frequency range of 10 to 80 Hzand a dominant frequency of 50 Hz In this formationaverage velocity is 4000 m∕s and the calculated Hminis 40 m (Table 1) This doubles the Hmin in this forma-tion for seismic imaging of clinoform complexes ineither LST or HST As a result seismic clinoformsare not imaged Instead these seismic events can beclassified as subparallel to discontinuous variable-amplitude seismic facies Each pair of seismic events(peak at bottom and trough at top) in each of thehigh-frequency sequences roughly represents a high-frequency sequence composed of a relative LST at thebottom and a relative HST at the top A strike seismicsection (Figure 8) shows a seismic facies distributionsimilar to that in the dip section (Figure 7) and fails
Fault- +
Amplitude
Shoreline Channellobe
Deltaplain
Deltafront
Prodeltalake
Direction ofprogradation
2 km2 km2 km
QAe1685
a)
c)
e)
b)
d)
f)
Figure 10 Three amplitude stratal slices (ac and e) at three high-frequency sequences(G31 G41 and SS2 respectively in Figure 7band labeled as a b and c in Figures 7b and 8)These slices interpreted as shallow-water del-tas are shown in (b d and f) respectivelyShorelines interpreted in (d and f) refer toposition of the successive shorelines duringprogradation
Interpretation August 2013 SA41
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
to reveal any seismic reflection configuration thatresembles the mound geometry associated with typicalprograding delta clinoforms (Figure 3b)
Lithology grain-size trend and sedimentary struc-ture were observed in conventional cores providingmore direct evidence for classifying depositional faciesBy describing more than 1300 m of core in 11 wells inthe area we recognized that most subfacies in the coreare related to fluvial-dominated deltaic deposition Forexample in a long cored section (Figure 9) a typicalfacies cycle (from bottom to top) includes gray shaleand thin limestone (Figure 9a) representing shallow-lake deposition trough-cross-stratified fine-grainedsandstone (Figure 9b) from the distributary channeland medium-grained blocky sandstone with shale-clastlag (Figure 9c) on the scoured distributary-channelbase in the delta front There are abundant ostracodfossils (eg Cypridea Candona Mongolocypris andZiziphocypris) identified in the limestones andshales all indicative of a shallow-water environmentRanging from 4- to 15-m thick the upward-coarseningsequences are a result of progradational processes ina shallow-water deltaic system (eg Olariu and Bhatta-charya 2006)
A set of stratal slices was constructed in the intervalbetween reference events T1 and T2 from stacked andmigrated data (Figure 7a) All the stratal slices roughlyfollow individual seismic events that are parallel toone another Selected slices (Figure 10a 10c and10e) represent three thin LST deltaic depositional sys-tems in high-order sequences The most striking seismicgeomorphologic features in these stratal slices are nu-merous channel patterns and associated amplitudeanomalies of different shapes representing variousdeltaic environments (Figure 10b 10d and 10f)Differences in the facies patterns reflect relative mar-gin-to-basin positions in the gentle slope of a postriftlacustrine basin During deposition of the high-frequency sequence SS2 (Figure 10a and 10b) the lakewas at its maximum depth and extent and the studyarea was a delta front Distributary channels extendedfar into the basin and were rarely exposed before burialA fringing sandy delta front was lacking Later duringdeposition of the high-frequency sequences G41(Figure 10c and 10d) and G31 (Figure 10e and 10f)the lake diminished in area after repeated deltaic-deposition episodes The study area is located in theshoreline area which has a narrower delta-front zoneThe deltaic system prograded on a smaller scale withdeltaic lobes forming one in front of another attachedto shorter distributary channels which terminated atthe shoreline at the time of deposition Multiple shore-line positions can be determined on the basis of channelterminations (Figure 10c and 10d) or amplitude zoning(Figure 10e and 10f) showing a general direction ofdeltaic progradation
Miocene deltas at the Gulf of MexicoLouisiana United States
Starfak and Tiger Shoal fields of offshore LouisianaUnited States (Figure 11) lie along the western periph-ery of the ancestral Mississippi River area Located inthe Oligocene-Miocene Detachment Province of thenorth Gulf Coast continental margin (Diegel et al1995) Miocene deposits are largely controlled bydown-to-the-basin listric growth faults that sole on aregional detachment zone above the Oligocene sectionSalt tectonics and growth faulting resulted in a greatthickness of deltaic and other on-shelf sediments duringa period of high sedimentation rates Interpreted depo-sitional environments include lowstand progradingwedge slope fan and basin-floor fan beyond the shelfedge incised valley highstand delta and transgressivefacies and coastal plain coastal delta and inner-shelfmarine deposits in the coastal area (Hentz and Zeng2003)
All these Miocene depositional systems are com-posed of interbedded sandstone and shale units withsandstones varying widely in thickness and rangingfrom 1 to 40 m Although the study area is situatedin a passive continental margin a representative dipseismic section across the area (Figure 12) demon-strates mostly parallel to divergent seismic facies
TEXAS
LOUISIANA
MISSISSIPPI
3D surveysField
N
VERMILIONAREA
SOUTH MARSHISLAND AREA
North LightHouse Point
TigerShoal
Starfak C
LOUISIANA
MARSH ISLAND
C
A
A
0
0
5 mi
8 km
B
B
LightHousePoint
Trinity Shoal
Amber Complex
Mound Point
Fig 13
QAe1686
Figure 11 Location of Starfak and Tiger Shoal fields 3Dseismic surveys and wells in the Louisiana Gulf Coast
SA42 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
(eg in the Daqing Oilfield area) Much of the deltaicsediment was deposited in very gentle slopes aroundthe basin margin in shallow waters lacking well-developed clinoforms
In the Qijia Depression (Figure 6) deltaic sedimentsconsist of gray and dark-gray mudstone interbeddedwith sandstone and siltstone A wireline-log-basedsequence-stratigraphic correlation (Figure 7a) revealedmultiple higher order sequences (G11 through SS1) inthree third-order sequences (SQ1 through SQ3) in theQingshankou Formation (Zeng et al 2012) In this22-km-long dip-oriented section thickness changesfrom updip to downdip are minor revealing a very gen-tle slope at the time of deposition Each of the higherorder sequences has an average thickness of approxi-mately 40 m which is composed of a relative lowstandsystems tract (LST) at the bottom and a relative high-stand systems tract (HST) at the top with roughly equalthickness (20 m)
A Wheeler-transformed equivalent of Figure 7a isrealized with stratal slicing processing (Figure 7b)which shows a good correlation between well-baseddepositional sequences and seismic events The 3Dseismic data have a frequency range of 10 to 80 Hzand a dominant frequency of 50 Hz In this formationaverage velocity is 4000 m∕s and the calculated Hminis 40 m (Table 1) This doubles the Hmin in this forma-tion for seismic imaging of clinoform complexes ineither LST or HST As a result seismic clinoformsare not imaged Instead these seismic events can beclassified as subparallel to discontinuous variable-amplitude seismic facies Each pair of seismic events(peak at bottom and trough at top) in each of thehigh-frequency sequences roughly represents a high-frequency sequence composed of a relative LST at thebottom and a relative HST at the top A strike seismicsection (Figure 8) shows a seismic facies distributionsimilar to that in the dip section (Figure 7) and fails
Fault- +
Amplitude
Shoreline Channellobe
Deltaplain
Deltafront
Prodeltalake
Direction ofprogradation
2 km2 km2 km
QAe1685
a)
c)
e)
b)
d)
f)
Figure 10 Three amplitude stratal slices (ac and e) at three high-frequency sequences(G31 G41 and SS2 respectively in Figure 7band labeled as a b and c in Figures 7b and 8)These slices interpreted as shallow-water del-tas are shown in (b d and f) respectivelyShorelines interpreted in (d and f) refer toposition of the successive shorelines duringprogradation
Interpretation August 2013 SA41
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
to reveal any seismic reflection configuration thatresembles the mound geometry associated with typicalprograding delta clinoforms (Figure 3b)
Lithology grain-size trend and sedimentary struc-ture were observed in conventional cores providingmore direct evidence for classifying depositional faciesBy describing more than 1300 m of core in 11 wells inthe area we recognized that most subfacies in the coreare related to fluvial-dominated deltaic deposition Forexample in a long cored section (Figure 9) a typicalfacies cycle (from bottom to top) includes gray shaleand thin limestone (Figure 9a) representing shallow-lake deposition trough-cross-stratified fine-grainedsandstone (Figure 9b) from the distributary channeland medium-grained blocky sandstone with shale-clastlag (Figure 9c) on the scoured distributary-channelbase in the delta front There are abundant ostracodfossils (eg Cypridea Candona Mongolocypris andZiziphocypris) identified in the limestones andshales all indicative of a shallow-water environmentRanging from 4- to 15-m thick the upward-coarseningsequences are a result of progradational processes ina shallow-water deltaic system (eg Olariu and Bhatta-charya 2006)
A set of stratal slices was constructed in the intervalbetween reference events T1 and T2 from stacked andmigrated data (Figure 7a) All the stratal slices roughlyfollow individual seismic events that are parallel toone another Selected slices (Figure 10a 10c and10e) represent three thin LST deltaic depositional sys-tems in high-order sequences The most striking seismicgeomorphologic features in these stratal slices are nu-merous channel patterns and associated amplitudeanomalies of different shapes representing variousdeltaic environments (Figure 10b 10d and 10f)Differences in the facies patterns reflect relative mar-gin-to-basin positions in the gentle slope of a postriftlacustrine basin During deposition of the high-frequency sequence SS2 (Figure 10a and 10b) the lakewas at its maximum depth and extent and the studyarea was a delta front Distributary channels extendedfar into the basin and were rarely exposed before burialA fringing sandy delta front was lacking Later duringdeposition of the high-frequency sequences G41(Figure 10c and 10d) and G31 (Figure 10e and 10f)the lake diminished in area after repeated deltaic-deposition episodes The study area is located in theshoreline area which has a narrower delta-front zoneThe deltaic system prograded on a smaller scale withdeltaic lobes forming one in front of another attachedto shorter distributary channels which terminated atthe shoreline at the time of deposition Multiple shore-line positions can be determined on the basis of channelterminations (Figure 10c and 10d) or amplitude zoning(Figure 10e and 10f) showing a general direction ofdeltaic progradation
Miocene deltas at the Gulf of MexicoLouisiana United States
Starfak and Tiger Shoal fields of offshore LouisianaUnited States (Figure 11) lie along the western periph-ery of the ancestral Mississippi River area Located inthe Oligocene-Miocene Detachment Province of thenorth Gulf Coast continental margin (Diegel et al1995) Miocene deposits are largely controlled bydown-to-the-basin listric growth faults that sole on aregional detachment zone above the Oligocene sectionSalt tectonics and growth faulting resulted in a greatthickness of deltaic and other on-shelf sediments duringa period of high sedimentation rates Interpreted depo-sitional environments include lowstand progradingwedge slope fan and basin-floor fan beyond the shelfedge incised valley highstand delta and transgressivefacies and coastal plain coastal delta and inner-shelfmarine deposits in the coastal area (Hentz and Zeng2003)
All these Miocene depositional systems are com-posed of interbedded sandstone and shale units withsandstones varying widely in thickness and rangingfrom 1 to 40 m Although the study area is situatedin a passive continental margin a representative dipseismic section across the area (Figure 12) demon-strates mostly parallel to divergent seismic facies
TEXAS
LOUISIANA
MISSISSIPPI
3D surveysField
N
VERMILIONAREA
SOUTH MARSHISLAND AREA
North LightHouse Point
TigerShoal
Starfak C
LOUISIANA
MARSH ISLAND
C
A
A
0
0
5 mi
8 km
B
B
LightHousePoint
Trinity Shoal
Amber Complex
Mound Point
Fig 13
QAe1686
Figure 11 Location of Starfak and Tiger Shoal fields 3Dseismic surveys and wells in the Louisiana Gulf Coast
SA42 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
to reveal any seismic reflection configuration thatresembles the mound geometry associated with typicalprograding delta clinoforms (Figure 3b)
Lithology grain-size trend and sedimentary struc-ture were observed in conventional cores providingmore direct evidence for classifying depositional faciesBy describing more than 1300 m of core in 11 wells inthe area we recognized that most subfacies in the coreare related to fluvial-dominated deltaic deposition Forexample in a long cored section (Figure 9) a typicalfacies cycle (from bottom to top) includes gray shaleand thin limestone (Figure 9a) representing shallow-lake deposition trough-cross-stratified fine-grainedsandstone (Figure 9b) from the distributary channeland medium-grained blocky sandstone with shale-clastlag (Figure 9c) on the scoured distributary-channelbase in the delta front There are abundant ostracodfossils (eg Cypridea Candona Mongolocypris andZiziphocypris) identified in the limestones andshales all indicative of a shallow-water environmentRanging from 4- to 15-m thick the upward-coarseningsequences are a result of progradational processes ina shallow-water deltaic system (eg Olariu and Bhatta-charya 2006)
A set of stratal slices was constructed in the intervalbetween reference events T1 and T2 from stacked andmigrated data (Figure 7a) All the stratal slices roughlyfollow individual seismic events that are parallel toone another Selected slices (Figure 10a 10c and10e) represent three thin LST deltaic depositional sys-tems in high-order sequences The most striking seismicgeomorphologic features in these stratal slices are nu-merous channel patterns and associated amplitudeanomalies of different shapes representing variousdeltaic environments (Figure 10b 10d and 10f)Differences in the facies patterns reflect relative mar-gin-to-basin positions in the gentle slope of a postriftlacustrine basin During deposition of the high-frequency sequence SS2 (Figure 10a and 10b) the lakewas at its maximum depth and extent and the studyarea was a delta front Distributary channels extendedfar into the basin and were rarely exposed before burialA fringing sandy delta front was lacking Later duringdeposition of the high-frequency sequences G41(Figure 10c and 10d) and G31 (Figure 10e and 10f)the lake diminished in area after repeated deltaic-deposition episodes The study area is located in theshoreline area which has a narrower delta-front zoneThe deltaic system prograded on a smaller scale withdeltaic lobes forming one in front of another attachedto shorter distributary channels which terminated atthe shoreline at the time of deposition Multiple shore-line positions can be determined on the basis of channelterminations (Figure 10c and 10d) or amplitude zoning(Figure 10e and 10f) showing a general direction ofdeltaic progradation
Miocene deltas at the Gulf of MexicoLouisiana United States
Starfak and Tiger Shoal fields of offshore LouisianaUnited States (Figure 11) lie along the western periph-ery of the ancestral Mississippi River area Located inthe Oligocene-Miocene Detachment Province of thenorth Gulf Coast continental margin (Diegel et al1995) Miocene deposits are largely controlled bydown-to-the-basin listric growth faults that sole on aregional detachment zone above the Oligocene sectionSalt tectonics and growth faulting resulted in a greatthickness of deltaic and other on-shelf sediments duringa period of high sedimentation rates Interpreted depo-sitional environments include lowstand progradingwedge slope fan and basin-floor fan beyond the shelfedge incised valley highstand delta and transgressivefacies and coastal plain coastal delta and inner-shelfmarine deposits in the coastal area (Hentz and Zeng2003)
All these Miocene depositional systems are com-posed of interbedded sandstone and shale units withsandstones varying widely in thickness and rangingfrom 1 to 40 m Although the study area is situatedin a passive continental margin a representative dipseismic section across the area (Figure 12) demon-strates mostly parallel to divergent seismic facies
TEXAS
LOUISIANA
MISSISSIPPI
3D surveysField
N
VERMILIONAREA
SOUTH MARSHISLAND AREA
North LightHouse Point
TigerShoal
Starfak C
LOUISIANA
MARSH ISLAND
C
A
A
0
0
5 mi
8 km
B
B
LightHousePoint
Trinity Shoal
Amber Complex
Mound Point
Fig 13
QAe1686
Figure 11 Location of Starfak and Tiger Shoal fields 3Dseismic surveys and wells in the Louisiana Gulf Coast
SA42 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lacking large-scale clinoform configurations Mostof the study interval was deposited on the on-shelfarea In particular most of the thin on-shelf deltaicsediments are interbedded with incised valley fills(IVFs) without displaying shingled clinoforms thatare representative of shallow-water deltas (Figure 4d)With a predominant frequency of around 35 Hz it isunderstandable that the seismic data are not able toimage clinoform complexes from deltas thinner thana calculated Hmin of 43 m (with 3000 m∕s velocity)A strike seismic profile (Figure 12b) demonstratessimilar parallel to subparallel reflection events withvariable amplitude and continuity without any indica-tion of mounded facies (Figure 3b)
An amplitude stratal slice (Figure 13a) that sam-ples one of the parallel and variable amplitude events(Figure 12) reveals multiple channel forms and asso-ciated amplitude anomalies of varying shapes whichcan be referred to as distributary channels and deltalobes Upward-coarsening wireline-log patterns in oneof the lobes indicate the sandy and progradingcharacter of the 30- to 35-m-thick delta system(Figure 13b) Because of the digitate shape of the an-
cient landform it is interpreted as a fluvial-dominateddelta having limited wave modification This delta sys-tem is so big that it obviously exceeds the 350-mi2
study area
Miocene Oakville deltas at the Gulf of MexicoTexas United States
In a 3D seismic survey in the Corpus Christi Bay areaof south Texas (Figure 14) the Miocene Oakville For-mation is bounded below by the upper OligoceneAnahuac Formation Sediments of the Oakville intervalform one of many thick offlapping wedges of terrig-enous sediment that were deposited in the deep Gulfof Mexico Basin during the late Tertiary (Brownand Loucks 2009) Oakville strata make up part of asecond-order regressive sequence of interbedded sand-stones and shales that followed a basinwide second-order transgression represented by the OligoceneAnahuac Formation (Brown and Loucks 2009)
Dip (Figure 15a) and strike (Figure 15b) seismic sec-tions across the study area demonstrate a mostlyparallel seismic configuration in the Oakville intervalwhich is the on-shelf portion of the thick Oakville off-
1600
1800
2000
2200
2400
2600
2800
Basinwarda)
b) 2000
2200
2400
2600
Tra
velti
me
(ms)
B B
ndash
Amplitude
+2 km0
0 2 mi 14
Fault IVF at high-freq sequence
A A
Tra
velti
me
(ms)
QAe1695
Figure 12 Seismic sections in Starfak andTiger Shoal area showing the lack of clino-forms in Miocene on-shelf deltaic sedimentsDashed lines refer to position of the stratalslice in Figure 13 (a) Northndashsouth dip sectionA-Aprime (modified from Zeng and Hentz 2004)(b) Westndasheast strike section B-Bprime SeeFigure 11 for position
Interpretation August 2013 SA43
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
lapping wedge The dominantly deltaic and shore-zonesediments exhibit a different depositional style fromthat in the offshore Louisiana study area (Figure 11)where a primary deltaic depocenter existed during theMiocene Instead multiple small streams transportedenormous volumes of locally derived sediments acrossthe coastal plain of Texas (Galloway 1986 Gallowayet al 2000) Galloway et al (2000) and Loucks et al(2011) find the older Oligocene shelf edge to be 20 to25 mi seaward (downdip) of the study area
An amplitude stratal slice made inside the OakvilleFormation (Figure 16) illustrates a unique channel-lobesystem that resembles some elongate branches of themodern Mississippi delta (eg Figure 2) in geometryand in size except for its inner-shelf location At leasteight mouth-bar lobes are seen attached to a sinuousdistributary-channel system Wireline log patterns inwells show that channel-filled sandstones do not ex-ceed 10 m at this interval falling below seismic resolu-tion Outside the channels and in between delta lobesshaly sediments dominate No seismic clinoforms areobserved along the depositional surface representedby the stratal slice (Figure 16) an indication of ashallow-water origin of the deltaic system The thick-ness of the delta complex should not exceed the calcu-
lated Hmin or 33 m based on a predominant frequencyof the seismic data of 35 Hz and a formation velocityof 2300 m∕s
Frequency control on clinoform seismicstratigraphy
A detailed outcrop-based acoustic impedance (AI)model (Figure 17a) of the Abo carbonate sequenceat Apache Canyon Sierra Diablo west Texas(Courme 1999) provides a realistic stratigraphic andfacies reference to study factors that control thetransition between seismic clinoforms and non-clinoforms of a prograding carbonate depositionalsystem The modeled high-frequency sequence is com-posed of multiple interbedded high-AI mudstonepackstone and low-AI grainstone clinoforms dippingat 10degndash20deg (average 15deg) Measured beds or bed setsrange in thickness from 3 to 10 m (landward) to 20to 60 m (basinward) The clinoforms can be character-ized as oblique (Figure 4b) because of the gradually re-duced slope downdip and a bypassed or slightly erodedtoplap surface beneath a thin irregular paleokarst sys-tem The whole Abo clinoform complex is encased inflat-lying host carbonate units (Wolfcamp and ClearFork) Judging from the geometry of component beds
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
200
0 0
60ft m
DATUM
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
SB 4
Third-order
Fourth-order
Fourth-order
SYSTEMS TRACT
Upp
er M
ioce
ne SB 3
W2NorthC Cacute
SouthW17 W9 W14 W8 W4
GR SP ILD GR SP SPILD GR ILD ILD
MFS 4
SPGR ILDSPGR ILDSPGR
2002
0 0
60ft m
DDAATUMTUMAAA
Highland (HST)
Lowstand (incised valley) (LST)Transgressive (TST)
Maximum flooding surfaceSequence boundaryMaximum flooding surfaceTransgressive surfaceSequence boundary
g
MFS 4SB 4
QAe1701
a)
b)
2 km
Direction ofprogradation
Channellobe
- +
Amplitude
Fault
Figure 13 A nonclinoform highstand on-shelf delta in a high-frequency sequence inStarfak and Tiger Shoal seismic surveys(modified from Hentz and Zeng 2003) (a) Arepresentative amplitude stratal slice illustrat-ing multiple channel forms and associatedamplitude anomalies of varying shapes in anon-shelf shallow-water delta (b) Well sectionC-Cprime showing high-frequency sequence corre-lation and stratal position of the stratal slice(modified from Hentz and Zeng 2003) Referto Figure 11 for the positions of the stratalslice and the well section
SA44 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
and the stacking pattern of the clinoforms the imped-ance layering of this system is comparable to that of adeltaic system at a similar scale
A set of synthetic seismic models (Figure 17bndash17f)constructed from the AI model (Figure 17a) illustratehow this clinoform complex responds to Ricker wave-lets of different predominant frequencies The 300-Hzmodel (Figure 17b) has more than enough resolutionto resolve all modeled clinoform beds or bed sets Asa result the seismic clinoform configuration is an accu-rate duplication of a geologic clinoform complex In the200-Hz model (Figure 17c) resolution is still goodenough to resolve most of the clinoforms but clinoformimages start to blur in the thinnest beds and the thinnestparts of the clinoform complex (eg box a in Figure 17c)A further reduction of the predominant frequency to100 Hz (Figure 17d) results in the disappearance of seis-mic clinoforms in some segments of the complex (egbox a part of box b) In the 75-Hz model (Figure 17e)the seismic clinoforms are gone except in the thickestpart of the clinoform complex (box c) Finally seismicclinoforms disappear altogether in the 50-Hz model(Figure 17f) instead we see a mostly flat event havingvariable amplitude and continuity
A more quantitative analysis suggests that the firstoccurrence of seismic clinoforms in this set of seismicmodels is closely related to Hmin (equations 1 and 2) Athinner clinoform complex needs data of higherpredominant frequency to image The clinoform com-plex shown in box a (Figure 17a) is about 15ndash20 m(5ndash7 ms) thick which requires seismic data of 150ndash200 Hz to image (box a in Figure 17c) For a clinoformcomplex of 30 m (10 ms) 100-Hz data are barelyadequate to show recognizable seismic clinoforms(box b in Figure 17d) If a clinoform complex is 45 m(15 ms) thick it will show up in a 75-Hz section (box cin Figure 17e)
It seems that the type of seismic clinoform configu-ration may also be related to data frequency An obliqueclinoform seismic configuration in higher frequencydata (eg 300-Hz section Figure 17b) tends to becomea shingled configuration in the lower frequency data(eg box b in Figure 17d box c in Figure 17e) As aresult shingled facies observed in seismic data arenot necessarily truly representative of geologic clino-form architecture The merging of seismic responsesof the thinner low-angle downdip portion of clinoformswith that from underlying flat host rocks in low-frequency data appears to distort the seismic faciesBiddle et al (1992) document in their outcrop modelingstudy that the seismic downlap surfaces do not corre-spond to discrete stratal surfaces but to the toe-of-slopeposition where major bedding units thin below seismicresolution Likewise seismic sigmoidal clinoforms maybe distorted by seismic toplaps corresponding to lithof-acies changes in sigmoidal geologic units Readers arereferred to Zeng and Kerans (2003 Figure 1) for a field-data example
Reducing ambiguity of seismic interpretationSeismic nonclinoforms of prograding depositional
systems pose a challenge to exploration and produc-tion geologists using seismic data The lack of arecognizable clinoform configuration may lead tomisinterpretation of a prograding system as a differentfacies For example without well data and stratal slicemapping the subparallel variable-amplitude reflectionsthat correlated with shallow-water deltas in Figures 712 and 15 could easily be misinterpreted as flood-plain shore-zone or shallow-water lakeshallow-watermarine facies the nonclinoform reflection in low-frequency seismic models of a shelf-edge carbonateclinoform complex (eg Figure 17f) could mistakenlybe interpreted as flat inner-shelf mudstones This ambi-guity in seismic interpretation may have significant con-sequences the most serious misinterpretation would beto drill a shallow-water delta play on the basis of a falseimpression about the continuity of shingled reservoirsthat actually pinch out at multiple toplap points A sim-ulation model based on flat and continuous reservoirbedding instead of clinoforms would further hinderdevelopment of remaining hydrocarbons in hetero-geneous reservoirs
B
BA
A
Laguna Madre
Padre Island MustangIsland
PortlandCorpus Christi
NuecesBay
N
TEXAS
Port Aransas
G u l f o f M e x i c o
C o r p u s
C h r i s t i B a y
Redfish Bay
Aransas Pass
10 km0
QAe1700
Figure 14 Corpus Christi Bay area in south Texas and loca-tion of 3D seismic survey used in the study
Interpretation August 2013 SA45
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
The ultimate solution to these problems is to pro-mote acquisition of high-resolution seismic data Basedon equation 2 and Table 1 in a data set of 200-Hzpredominant frequency Hmin will reduce to 5 m (for2000 ms clastic rocks) to 15 m (for 6000 ms carbonaterocks) which would greatly enhance our ability tovisually interpret thin-bedded seismic clinoformsSome new technologies in high-resolution acquisitionhave been developed in recent years Among them Qtechnology (Goto et al 2004) and high-density 3Dtechnology (Ramsden et al 2005) have probably metwith the most success
Where the current high cost of acquisition of high-resolution seismic data may not be suitable a high-frequency enhancement processing of available seismicdata would help Spectral balancing (Tufekcic et al1981) spectral decomposition (Partyka et al 1999)inverse spectral decomposition (Portniaguine andCastagna 2004) and wavelet transform (eg Smithet al 2008 Devi and Schwab 2009) are some of the
most useful methods Figure 18 shows an example inthe Abo Kingdom carbonate field of west Texas of usingthe spectral balancing method to increase the pre-dominant frequency of data for better clinoform imag-ing The original stacked and migrated seismic data(Figure 18a) are characterized by a frequency rangeof 10 to 70 Hz and a predominant frequency of30 Hz Some toplaps are seen terminated against a non-clinoform flat reflection of strong amplitude Followinga spectral balancing process (Figure 18b) the predomi-nant frequency of the data increases to 45 Hz resultingin a breakup of the flat event in the original data (Fig-ure 18a) into several clinoforms It appears that thesenewly imaged clinoforms are part of a large sigmoidalclinoform complex that lacks an inside toplap surface
However the process of high-frequency enhance-ment inevitably lowers the signal-to-noise ratio of thedata and therefore has its limit Caution should betaken not to artificially push the predominant fre-quency beyond the bandwidth of the data For many
- +
Amplitude
a)
b)
Basinward
1 km
Fault
AnahuacAnahuac
FrioFrio
OakvilleOakville
A
B B
B
QAe1696
AnahuacAnahuac
FrioFrio
OakvilleOakville
Tra
velti
me
(ms)
Tra
velti
me
(ms)
1000
1500
2000
1000
Figure 15 Seismic sections in the CorpusChristi area showing the lack of clinoformsin Miocene Oakville on-shelf deltaic sedi-ments Dashed lines refer to position of thestratal slice in Figure 16 (a) Dip sectionA-Aprime (b) Strike section B-Bprime Refer to Figure 14for position
SA46 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
areas where only low-frequency data are available orthe clinoform complexes are too thin (eg theshallow-water deltas investigated in this paper)an integrated approach that combines the use ofcore wireline logs production data and seismicgeomorphology should be adapted Unique landformson seismic stratal slices that are representative of vari-ous deltaic systems can alert interpreters to the pos-sible existence of shingled reservoir architecture inthe form of nonclinoform reflections Multiple longterminal distributary-channel forms (Figure 10a)stepwise termination of distributary-channel forms(Figure 10b) amplitude zoning (Figure 10c) and dig-itate (Figure 13a) and elongate (Figure 16) areal geom-etries are good examples of indicators of the presenceof thin below-seismic-resolution deltas For detailedreservoir prediction and characterization seismic lith-ology should also be investigated so that a 3D seismicvolume can first be converted into a log lithology vol-ume In a lithology volume lithology logs (eg gamma-ray and spontaneous potential) at well locations aretied to nearby seismic traces within a small toleranceensuring the best possible well integration with seis-mic data at the reservoir level Using seismic geomor-phology researchers can convert seismic data further
into depositional facies images with lithologic identifi-cation Such an approach is called seismic sedimentol-ogy (Zeng and Hentz 2004)
QAe1697
SPReslogs
Channellobe
Direction ofprogradation
WellFault
N
Amplitude500 m
- +
Figure 16 A representative amplitude stratal slice revealinga nonclinoform on-shelf delta in the Miocene Oakville Forma-tion in the Corpus Christi seismic survey
QAe1698
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
a)AI
b) 300 Hz
f ) 50 Hze)
75 Hz
d) 100 Hz
c) 200 Hz
Hmin
Hmin Hmin
Hmin Hmin
bbaa cc
AboAboWWolfcampolfcamp
Clear ForkClear Fork
bbaaccbacbac
bbaaccbacbac bbaa
ccbacbac
Figure 17 An AI model of the Abo carbonateclinoform complex at Apache Canyon SierraDiablo west Texas (Courme 1999) and itssynthetic seismic responses with Ricker wave-lets of various frequencies For better com-parison with field data the predominantfrequency is used in modeling which is equalto 13 times the peak frequency for Rickerwavelet Clinoform detection limits are calcu-lated from equation 1 Boxes a b and c denoterelatively thin moderate and thick clinoformcomplexes in the model respectively
Interpretation August 2013 SA47
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
ConclusionsThe seismic configuration of a prograding depositio-
nal sequence is related to the water depth of the receiv-ing basin Although deep-water (shelf-edge) deltas thatwere deposited in water depths of high tens to hundredsof meters can easily be resolved by seismic data as seis-mic clinoforms the clinoforms in shallow-water deltasdeveloped in water depths of meters to low tens of me-ters tend to be unrecognized by their seismic responsesin the form of seismic nonclinoforms The clinoformdetection limit (Hmin) can be defined as one wavelength(width of two seismic events) and is related to the pre-dominant frequency of the seismic data and the velocityof the prograding sediments
Ancient nonclinoform shallow-water deltas devel-oped in lacustrine and marine environments have beeninterpreted from low-frequency stacked and migratedseismic data by integrated use of core wireline logsand amplitude stratal slices The diagnostic seismicgeomorphologic patterns include but are not limitedto multiple long terminal distributary-channel formsstepwise termination of distributary-channel forms am-plitude zoning and digitate and elongate areal landformgeometries
Our outcrop seismic modeling shows the seismicfrequency control on clinoform seismic stratigraphyWhen the predominant frequency of a seismic waveletdecreases an oblique clinoform pattern tends to be-come a shingled clinoform configuration and when thethickness of a clinoform complex reaches Hmin a tran-sition from seismic clinoforms to seismic nonclino-forms occurs
The interpretation of progradational depositional se-quences needs to go beyond the recognition of seismicclinoforms using traditional seismic facies analysis oflow-frequency seismic data Ambiguity in interpretingnonclinoform seismic facies can be effectively reducedby high-resolution acquisition high-frequency enhance-ment processing and seismic sedimentology
AcknowledgmentsWe thank Q Zhang Y Sun R Wang C Zhou and B
Bai for their contribution to the study The authors alsoextend gratitude to PetroChina and Chevron for provid-ing well and seismic data Landmark Graphics Corpora-tion provided software via the Landmark UniversityGrant Program for the interpretation and display of seis-mic data The authors thank INTERPRETATION reviewers COlariu and R Loucks for their constructive commentsand suggestions Figures were prepared by C Brownand J Lardon S Doenges edited the text Publicationwas authorized by the director Bureau of EconomicGeology Jackson School of Geosciences The Univer-sity of Texas at Austin
ReferencesBelopolsky A V and A W Droxler 2004 Seismic expres-
sions of prograding carbonate bank margins MiddleMiocene Maldives Indian Ocean in G P EberliJ L Masaferro and J F Sarg eds Seismic imagingof carbonate reservoirs and systems AAPG Memoir81 267ndash290
Berg O R 1982 Seismic detection and evaluation of deltaand turbidite sequences Their application to explora-tion for the subtle trap AAPG Bulletin 66 1271ndash1288
Bhattacharya J P and R G Walker 1991 River- andwave-dominated depositional systems of the UpperCretaceous Dunvegan Formation northwestern Al-berta Bulletin of Canadian Petroleum Geology 39165ndash191
Biddle K T W Schlager K W Rudolph and T L Bush1992 Seismic model of a progradational carbonate
25 m
s
500 m
a)
b)
- +
Amplitude QAe1699
Figure 18 Reducing ambiguity in interpreting nonclinoformprograding sequences by spectral balancing (a) Originalstacked andmigrated seismic section in Abo Kingdom carbon-ate field of west Texas with a flat (dashed line) event andsome toplapped events (arrows) underneath (b) The samesection after spectral balancing processing The flat eventin the original data has been broken up into clinoforms(dashed lines) having slopes similar to those of surroundingevents The toplaps disappear
SA48 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
platform Picco di Vallandro the Dolomites NorthernItaly AAPG Bulletin 76 14ndash30
Brown L F Jr and R G Loucks 2009 Chronostratigra-phy of Cenozoic depositional sequences and systemstracts A Wheeler chart of the northwest margin ofthe Gulf of Mexico Basin The University of Texas atAustin Bureau of Economic Geology Report of Inves-tigations 273
Busch D A 1959 Prospecting for stratigraphic trapsAAPG Bulletin 43 2829ndash2843
Busch D A 1971 Genetic units in delta prospectingAAPG Bulletin 55 1137ndash1154
Carvajal C and R J Steel 2009 Shelf-edge architectureand bypass of sand to deep water influence of shelf-edge processes sea level and sediment supply Journalof Sedimentary Research 79 652ndash672 doi 102110jsr2009074
Cleaves A W and M C Broussard 1980 Chester andPottsville depositional systems outcrop and subsur-face in the Black Warrior Basin of Mississippi and Ala-bama Gulf Coast Association of Geological SocietiesTransactions 30 49ndash60
Courme B 1999 Forward seismic modeling of a shelf-to-slope carbonate depositional setting from outcrop datathe Abo Formation of Apache Canyon West Texas andcomparison to its subsurface equivalent Kingdom Abofield Midland Basin MS thesis The University ofTexas at Austin p 200
Covault J A B W Romans and S A Graham 2009 Out-crop expression of a continental-margin-scale shelf-edge delta from the Cretaceous Magallanes BasinChile Journal of Sedimentary Research 79 523ndash539doi 102110jsr2009053
Devi K R S and H Schwab 2009 High-resolution seis-mic signals from band-limited data using scaling laws ofwavelet transforms Geophysics 74 no 2 WA143ndashWA152 doi 10119013077622
Diegel F A J F Karlo D C Schuster R C Shoup andP R Tauvers 1995 Cenozoic structural evolution andtectonostratigraphic framework of the northern GulfCoast continental margin in M P A Jackson D GRoberts and S Snelson eds Salt tectonics A globalperspective AAPG Memoir 65 109ndash151
Dixon J F J F Dixon R J Steel and C Olariu 2012River-dominated shelf-edge deltas delivery of sandacross the shelf break in the absence of slope incisionSedimentology 59 1133ndash1157 doi 101111j1365-3091201101298x
Droste H and M V Steenwinkel 2004 Stratal geometriesand patterns of platform carbonates The Cretaceous ofOman in G P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 185ndash206
Eberli G P F S Anselmetti C Betzler and J VKonijnenburg 2004 Daniel Bernoulli carbonate plat-form to basin transitions on seismic data and in
outcrops Great Bahama Bank and the Maiella platformmargin Italy in G P Eberli J L Masaferro andJ F Sarg eds Seismic imaging of carbonate reservoirsand systems AAPG Memoir 81 207ndash250
Ethridge F G and W A Wescott 1984 Tectonic settingrecognition and hydrocarbon reservoir potential of fan-delta deposits in E H Koster and R J Steel eds Sed-imentology of gravels and conglomerates CanadianSociety of Petroleum Geologists Memoir 10 217ndash235
Feng Z Q C Z Jia X N Xie S Zhang Z H Feng andT A Cross 2010 Tectonostratigraphic units and strati-graphic sequences of the nonmarine Songliao Basinnortheast China Basin Research 22 79ndash95 doi 101111j1365-2117200900445x
Fisher W L L F Brown Jr A J Scott and J HMcGowen 1969 Delta systems in the exploration foroil and gas mdash A research colloquium The Universityof Texas at Austin
Galloway W E 1975 Evolution of deltaic systems inDeltas models for exploration Houston GeologicalSociety 8 7ndash89
Galloway W E 1986 Reservoir facies architecture of mi-crotidal barrier systems AAPG Bulletin 70 787ndash808
Galloway W E P E Ganey-Curry X Li and R T Buffler2000 Cenozoic depositional history of the Gulf ofMexico Basin AAPG Bulletin 84 1743ndash1774 doi 1013068626C37F-173B-11D7-8645000102C1865D
Galloway W E and D K Hobday 1983 Terrigenous clas-tic depositional systems Springer-Verlag p 423
Goto R D Lowden P Smith and J O Paulsen 2004Steered-streamer 4D case study over the Norne field74th Annual International Meeting SEG ExpandedAbstracts 2227ndash2230
Hentz T F and H Zeng 2003 High-frequency Miocenesequence stratigraphy offshore Louisiana Cycle frame-work and influence on production distribution in a ma-ture shelf province AAPG Bulletin 87 197ndash230 doi 10130609240201054
Isern A R F S Anselmetti and P Blum 2004 A Neogenecarbonate platform slope and shelf edifice shaped bysea level and ocean currents Marion Plateau (NortheastAustralia) inG P Eberli J L Masaferro and J F Sargeds Seismic imaging of carbonate reservoirs and sys-tems AAPG Memoir 81 291ndash308
Li W J P Bhattacharya Y Zhu D Garza andE L Blankenship 2011 Evaluating delta asymmetry us-ing three-dimensional facies architecture and ichnologi-cal analysis Ferron lsquoNotom Deltarsquo Capital Reef UtahUSA Sedimentology 58 478ndash507 doi 101111j1365-3091201001172x
Lou Z H X Lan Q M Lu and X Y Cai 1999 Controls ofthe topography climate and lake level fluctuation onthe depositional environment of a shallow-water delta(in Chinese) Acta Geologica Sinica 73 83ndash92
Loucks R G B T Moore and H Zeng 2011 On-shelflower Miocene Oakville sediment-dispersal patterns
Interpretation August 2013 SA49
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
within a three-dimensional sequence-stratigraphic ar-chitectural framework and implications for deep-waterreservoirs in the central coastal area of Texas AAPGBulletin 95 1795ndash1817
Mitchum R M Jr P R Vail and B Sangree 1977 Seis-mic stratigraphy and global change of sea level Part 6Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 117ndash134
Olariu C and J P Bhattacharya 2006 Terminal dis-tributary channels and delta front architecture ofriver-dominated delta systems Journal of SedimentaryResearch 76 212ndash233 doi 102110jsr2006026
Olariu M I C R Carvajal C Olariu and R J Steel 2012Deltaic process and architectural evolution duringcross-shelf transits Maastrichtian Fox Hills FormationWashakie Basin Wyoming AAPG Bulletin 96 1931ndash1956 doi 10130603261211119
Partyka G J Gridley and J Lopez 1999 Interpretationalapplication of spectral decomposition in reservoir char-acterization The Leading Edge 18 353ndash360 doi 10119011438295
Portniaguine O and J P Castagna 2004 Inverse spectraldecomposition 74th Annual International MeetingSEG Expanded Abstracts 1786ndash1789
Postma G 1990 An analysis of the variation in delta ar-chitecture Terra Nova 2 124ndash130 doi 101111j1365-31211990tb00052x
Ramsden C G Bennett and A Long 2005 High resolu-tion 3D seismic imaging in practice The Leading Edge24 423ndash428 doi 10119011901397
Rasmussen D L C J Jump and K A Wallace 1985 Del-taic systems in the Early Cretaceous Fall River Forma-tion southern Powder River Basin Wyoming WyomingGeological Association 36 91ndash111
Rich J L 1951 Three critical environments of depositionand criteria for recognition of rocks deposited ineach of them Geological Society of America Bulletin62 1ndash20 doi 1011300016-7606(1951)62[1TCEODA]20CO2
Sangree J B and J M Widmier 1977 Seismic stratigra-phy and global changes of sea level Part 9 Seismic inter-pretation of clastic depositional facies in C E Paytoned Seismic stratigraphy AAPG Memoir 26 165ndash184
Smith M G Perry A Bertrand J Stein and G Yu 2008Extending seismic bandwidth using the continuouswavelet transform First Break 26 97ndash102
Tufekcic D J F Claerbout and Z Rasperic 1981 Spec-tral balancing in the time domain Geophysics 461182ndash1188 doi 10119011441258
Vail P R R M Mitchum Jr and S Thompson III 1977Relative change of sea level from coastal onlap Part 3Stratigraphic interpretation of seismic reflection pat-terns in depositional sequences in C E Payton edSeismic stratigraphy AAPG Memoir 26 63ndash82
Van Wagoner J C H W Posamentier R M MitchumP R Vail J F Sarg T S Loutit and J Hardenbol
1988 An overview of the fundamentals of sequencestratigraphy and key definitions in C K Wilgus BS Hastings H Posamentier J V Wagoner C A Rossand C Kendall eds Sea-level changes An integratedapproach SEPM Special publication no 42 1271ndash1288
Zeng H M M Backus K T Barrow and N Tyler 1998aStratal slicing Part I Realistic 3-D seismic model Geo-physics 63 502ndash513 doi 10119011444351
Zeng H S C Henry and J P Riola 1998b Stratal slicingPart II Real seismic data Geophysics 63 514ndash522 doi10119011444352
Zeng H and T F Hentz 2004 High-frequency sequencestratigraphy from seismic sedimentology Applied toMiocene Vermilion Block 50 Tiger Shoal area offshoreLouisiana AAPG Bulletin 88 153ndash174 doi 10130610060303018
Zeng H and C Kerans 2003 Seismic frequency controlon carbonate seismic stratigraphy A case study ofthe Kingdom Abo sequence West Texas AAPG Bulle-tin 87 273ndash293 doi 10130608270201023
Zeng H X Zhu R Zhu and Q Zhang 2012 Guidelines forseismic sedimentologic study in non-marine postrift ba-sins (in Chinese) Petroleum Exploration and Develop-ment 39 275ndash284 doi 101016S1876-3804(12)60045-7
Zou C N W Z Zhao X Y Zhang P Luo L Wang L HLiu S H Xue X J Yuan R K Zhu and S H Tao 2008Formation and distribution of shallow-water deltas andcentral-basin sandbodies in large open depression lakebasins (in Chinese) Acta Geologica Sinica 82 813ndash825
Hongliu Zeng received a BS (1982)
and an MS (1985) in geology from
the Petroleum University of China and
a PhD (1994) in geophysics from the
University of Texas at Austin He is a
senior research scientist for the Bureau
of Economic Geology Jackson School
of Geosciences The University of Texas
at Austin His research interests include seismic sedimentol-
ogy seismic interpretation and attribute analysis He won the
Pratt Memorial Award from AAPG in 2005
Xiaomin Zhu received BS (1982) MS
(1985) and PhD (1990) degrees in
petroleum geology from the Petroleum
University of China He is a professor
in the College of Geosciences China
University of Petroleum at Beijing
China His research interests include
lacustrine sedimentology sequence
stratigraphy and seismic sedimentology He won the Li
Siguang Award from the foundation of Li Siguang geological
scientific award in 2009
SA50 Interpretation August 2013
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org
Rukai Zhu received a BS (1988) in
geology from Hunan University of Sci-
ence and Technology an MS (1991) in
geology from China University of Geo-
sciences and a PhD (1994) in geology
from Peking University He is a senior
geologist for the Research Institute of
Petroleum Exploration amp Development
PetroChina His research interests include sedimentology
reservoir characterization and unconventional petroleum
geology
Interpretation August 2013 SA51
Dow
nloa
ded
101
413
to 1
861
122
432
38 R
edis
trib
utio
n su
bjec
t to
SEG
lice
nse
or c
opyr
ight
see
Ter
ms
of U
se a
t http
lib
rary
seg
org