PhD Thesis 2008

Z.E.YILDIZELJune, 2008

DEPOSITIONAL STACKING PATTERNS AND CYCLES

OF

GARZAN FORMATION IN THE GARZAN-GERMİK OIL

FIELD: AN APPROACH TO CYCLE TO LOG

CORRELATION

BY

ZEYNEP ELİF GAZİULUSOY YILDIZEL

June 2008


Outline of the Presentation

1. Introduction (8 slides)– The methodology

– The location and general geology of the study area

– General acceptances about GR and SONIC logs

2. Microfacies, cycles types, depositional environment

and stacking patterns of the Garzan Formation (10

slides)

3. An example to some of the studied wells (3 slides)

4. Cycle to log correlation (4 slides)

5. Discussions and conclusions (3 slides)


Acknowledgements

• Prof. Dr. Demir Altıner

• Mr. Mehmet Sünnetçioğlu, Mrs. Ekmel Uygur,

• TPAO management, A. Faruk Öner (24th October 2003 GM authorization)

• My Family

• Dr. Ali Yıldızel

• Miss. Zeynep Ezgi Yıldızel. She gives meaning to my life being my daugther


Purpose Of The Study

• To find a direct correlation with the cycles?, facies?, stacking patterns? with the logs of the Garzan Formation

• To achieve this purpose;– Microfacies of the Garzan Formation are described by using

Dunham (1962)– Depositional environment is comprehended– Cycle types are defined from microfacies and the stacking

patterns of the Garzan Formation is outlined– Log correlation with the cycles and stacking patterns is

interpreted

1. Introduction


Geographical Setting and Historical Precedence of the Garzan-Germik Oil Field

• 45km west of Siirt and 120km east of Diyarbakır town

• Fields are on surface anticline trending NW-SE

• 1944-1989 107 wells on Garzan field (73 oil well)

• 1957-1988 23 wells on Germik field (2 oil well)

• MTA discovered the field in 1950 by Garzan-2

• Second field discovered in Türkiye after Raman• Avarage porosity is 10% and permeability is 10md in Garzan field• Avarage porosity is 15% and permeability is 10md in Germik field.

• Thickness 190m in Garzan field.

• Thickness 150m in Germik field.

• 45810823 bbl (April 2008)

• Garzan field oils 26.4o API

• Germik field oils 19oAPI

1. Introduction

GARZAN FIELD

14

73

62

57

0

10

20

30

40

50

60

70

DRY WELL OIL WELL DRY WELLwith OILSHOW

ABANDONEDFOR

TECHNICAL

WATER WELL INJECTIONWELL

GERMİK FILED

3

2

0

10

7

00

2

4

6

8

10

DRY WELL OIL WELL DRY WELLwith OILSHOW

ABANDONEDFOR

TECHNICAL

WATER WELL INJECTIONWELL


Geological Map of the Study Area

• Hoya Fm. (Middle-Upper Eocene) exposed on the crest

• Germik (U. Eocene-Oligocene) and Şelmo (Miocene) outcrop along the flanks

• General trend is NW-SE

1. Introduction

Garzan-Germik Oil Fİeld

B. Raman Raman

Kentalan

Softek

Hazro


Major Structures of Southeast Anatolia

modified from Perinçek et. al., 1987)

1. Introduction


Top Garzan Formation

•Top Garzan map

•Highest subsurface elevation is at Garzan- 23 well

•The lowest subsurface elevation is at Germik-3 well

1. Introduction


Geology and Stratigraphy of Garzan Formation

• Garzan Formation is firstly defined as Kıradağ reef

limestone by Schmidt in 1961 and named as Garzan Reef

limestone by Kellog in 1961 under the subsurface.

• Maastrichtian in age

• Subtidal to open marine carbonate

1. Introduction


Base Map of the Study

1. Introduction


Basic Terminology SONIC and GR logs

• The sonic log provides a formations interval

transit time which is the reciprocal of the

velocity. (1/v) (msec/feet).

• the sonic log is sensitive to subtle textural

variations and it can help to identify the

lithology.

• Sonic log is used for correlation because of its

distinctive characteristic.

• The radioactivity of the rock measured by GR log tool is generally a direct function of the clay mineral content and this grain size and depositional environment.

• Gamma ray logs are often used to infer changes in depositional energy, with increasing radioactivity reflecting increasing clay content with decreasing depositional energy.

• The GR log can be used to correlate and to suggest facies and sequences and to identify lithology.

• Carbonates in their pure state are not radioactive and this aids their identification. However, carbonates contain organic matter and this is frequently radioactive due to uranium.

• Shapes on gamma ray log can be interpreted as grain size trends and by sedimentological association as facies succession

1. Introduction

The correlation of log shape with grain size trend is tenable only under very limited conditions. A universal application of gamma ray log shape to grain size trend and depositional facies is wrong (Rider, 1990)


Microfacies Types Of The Garzan Formation

• Miliolid Wackestone• Rotalid Miliolid Wackestone• Orbitoid Miliolid Wackestone• Pelagic Foraminiferal Mudstone• Rudist Wackestone

2. Microfacies

• subtidal, backshoal, shoal, foreshoal and open marine environment are present.

• The supratidal, intertidal and slope facies are not present in this study.


Miliolid Wackestone Subtidal Environment

• miliolids 1%-20%, • cuneolins 2%, • other benthic foraminifers 1%-4%, • matrix 60%-80%, • orbitoids 1% as fragments, • algs 1%-3%, • pelecypods and gastropods 1%-5%, • echinoid fragments 1%-6%, • rotalids 1%-3%, • osracodes 1%-4%

2. Microfacies

Miliolid Wackestone

0.43 0.93 0

6.483.95

02.4 1.48 0.55 1.04 0

2.08

78.73

1.93

0

10

20

30

40

50

60

70

80

ava

rag

e %

md?

avarage

Germik-21 well (X4, core) (m:miliolid, d:disyclina?)


Rotalid Miliolid Wackestone Shoal to Foreshoal

• rudist fragments (2%-4%), • miliolids (1%-20%), • algs (1%), • coral fragments (2%), • echnoid fragments (1%-3%), • pelecypods and gastropods (1%-6%), • cuneolins (1%), • rotalids (12%-40%), • other benthic foraminifers (2%-5%), • matrix (40%-70) • ostracode (1%-5)

2. Microfacies

Rotalid-Miliolid Wackestone

0.01 0.49 0.87

10.23

0 0.52 1.61 2.040.46

20.54

02.38

57.94

2.91

0

10

20

30

40

50

60

av

ara

ge

%

avarage

G. Germik-1 well (X4, cutting), (o: orbitoid, ro: rotalid, r:rudist).

oro

ror


Orbitoid Miliolid Wackestone Backshoal to Shoal

• orbitoides (2%-24%), • rudist fragments (20%-36%), • echinoid fragments (2%-30%), • rotalids (2%-16%),• matrix (20%-70%),• miliolids (%-11%), • algs (1%), • coral fragments (2%-7%), • pelecypods and gastropods (2%-11%), • cuneolins (1%), • other benthic foraminifers (2%-10%), • ostracodes (2%-6%) • pelagic foraminifers are absent

Orbitoid-Miliolid Wackestone

11.30

0.61

9.41

2.060.00

1.41

8.86

2.99

0.08

8.30

0.00

2.35

50.43

2.20

0

10

20

30

40

50

60

avar

age

%

2. Microfacies

avarage

o

r

Garzan-31 well (X4, core), (o:orbitoid, r:rudist).


Pelagic Foraminiferal Mudstone Foreshoal to Open Marine

• pelagic foraminifera (6%-20%) • matrix (70%-90%) • orbitoids (1%-7%), • other benthic foraminifera • pelecypods and gastropods (1%), • ostracodes (5%)

Pelagic Foraminiferal Mudstone

1.900.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00

14.77

0.33

81.00

1.98

0

10

20

30

40

50

60

70

80

90

ava

rag

e %

Garzan-23 well (X10, cutting), (p: planktonic foraminifera).

2. Microfacies

avarage


Rudist Wackestone Backshoal to Shoal

• rudist fragments (3%-54%),

• echinoid fragments (3%-15%),

• pelecypods and gastropods (1%-9%)

• matrix (30%-90%)

• orbitoids and ostracodes (1%),

• miliolids (1%-4%),

• coral fragments (2%),

• rotalids (1%)

• other benthic foraminifera (3%-23%)

Rudist Wackestone

0.76 0.00

27.89

0.81 0.00 0.53

7.444.94

0.00 0.32 0.00

6.23

50.90

0.170

10

20

30

40

50

60

av

ara

ge

%

Garzan-95 well (X4, core), (r:rudist, b:bryozoan?)

2. Microfacies

avarage


Cycle Types Of Garzan Formation

2. Cycles

• Type A• Type B• Type C• Type D• Type E


Cycle Stacking in the Garzan Formation

2. Cycles


Stacking Patterns and Their GR lgos

2. Stacking Patterns


Depositonal Environment of the Garzan Formation

2. Depositional environment


G.Germik-1

• Garzan fm (1957-2091m)• 134m Garzan thickness• GR-SONIC

3. Wells


Garzan-82

• Garzan fm (1553-1719m)• 166m Garzan thickness• SP-SONIC

3. Wells


Garzan-23

• Garzan fm (1461-1524m)• 63m Garzan thickness• GR-Resistivity

3. Wells


Generalized Log Patterns of the Garzan Formation

4. Cycle to Log


GR log _Germik-21, G. Germik-1, G. Germik-2, Garzan-33, Garzan-31 and Garzan-23

• G.Germik-2 is not examined on the thin esction basis fo microfacies but the log patterns and log to sysle stacking correlation made it possible to evaluate well and to correlate it with the others.

• Also Garzan-31 and 33 has a limited amount of thin section but the log patterns made it easy to be correlated with others.

4. Cycle to Log


SONIC log _ Germik-21, G. Germik-1, G. Germik-2 and Garzan-82

4. Cycle to Log

?


Germik-21 (GR), Garzan-33 (GR), Garzan-43 (Resistivity) and Garzan-82

4. Cycle to Log


Results

•Type A and D cycles are retrogradational meaning net landward movement of the facies. Meaning deepening in the cycle.

•They have to have an increasing trend in the GR so that the relatively deeper facies overly relatively shallower facies.

•On the contrary they show decreasing tren in GR values.

•Type E cycle is progradational meaning net movement of facies towards basin. It has to show a decreasing trend in GR readings menaing that the shallower facies overly the deeper ones. (decrease in clay content)

•On the contrary type E cycle has relatively increasing trend in GR.

5. Discussion and Conclusions

50o


Results

•The deposition of the Garzan Formation is a deepening upward cycle and is deposited during the major transgression of Maastrichtian .

•The stacking patterns of more deeper faices on to shallower ones represents the trangressive phase and the other two high stand systems tract are generally characterized by aggradational type except type E cycle.

•The cycles are capped by Miliolid Wackestone facies (type A, B, C, and E cycles) and Pelagic Foraminiferal Mudstone facies (type D cycle) because o f the rise on sea level is so much that the carbonate production could not keep up and grade into more clay rich facies.

• subtidal environment enlarges because of rapidly rising sea level. This leads to the domination of muddy cycles in the environment.

•At the top of the Garzan Formation deposition the rapid rising reached to a maximum level that the open marine conditions start to dominate the deposition

5. Discussion and Conclusions


Conclusions• Orbitoid Miliolid Wackestone and Rudist Wackestone of back shoal to shoal , Miliolid Wackestone facies of

subtidal, Rotalid Miliolid Wackestone of shoal to fore shoal and Pelagic Foraminiferal Mudstone of fore

shoal to open marine environment.

• type A cycle (retrogradational) deposited during transgressive systems tract, type B cycle (aggradational)

deposited during high stand systems tract, type C cycle (aggradational) deposited during high stand

systems tract, type D cycle (retrogradational) deposited during the upper transgressive systems tract, type

E cycle (progradational) deposited during high stand systems tract deposition. there is also the maximum

flooding surface located usually at the top of type D cycle .

• The base Garzan starts with type E and C cycles. Then type A cycle overlies type C cycle and this onset is

represented by type 2 sequence boundary. Over type A cycle there is an alternation of type B and C cycles

and this part of the deposition is an aggradational type of deposition. The top Garzan is defined by type D

cycle and maximum flooding surface ends up the Garzan Formation deposition. Below the type D cycle

there is the second type 2 sequence boundary.

• The maximum flooding surfaces are located towards the top of the wells at the onset of Alt Germav

deposition.

• The overall Garzan Formation deposition is transgressive and the formation shows deepening upward trend

which is deposited during the major transgression of Maastrichtian.

• The standard GR interpretation is not applicable in most of the carbonates and in Garzan Formation in

Garzan-Germik oil field. In Garzan deposition a decrease in GR readings indicates a decrease in energy and

relatively deepening with domination of deeper facies.. Besides an increase in GR readings indicate an

increase in energy and the domination of shallow water facies. In carbonate depositional environments

when GR reading increases in API this should not be interpreted as trangressive cycles without any facies

control.

• The Garzan Formation in Garzan- Germik oil field can be interpreted on the basis of cycles and system

tracts without any microfacies control by using the generalized log patterns. This correlation can be carried

out whole through the field.

.5. Discussion and Conclusions


DEPOSITIONAL STACKING PATTERNS AND CYCLES

OF

GARZAN FORMATION IN THE GARZAN-GERMİK OIL

FIELD: AN APPROACH TO CYCLE TO LOG

CORRELATION

BY

ZEYNEP ELİF GAZİULUSOY YILDIZEL

June 2008

PhD Thesis 2008

Presentations & Public Speaking

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