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ENVS 337

BASINS: FORMATION,FILLING & RESOURCES

Lecture 1

Dr Rob Duller

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Staff: Rob Duller, J im Marsh al l

Richard Word en

Slots : Mon days @ 1100 (Herd m an)

Tuesd ay @ 0900 (Chad -B ark)

Asses smen tExam 50%

Pract ic al w or k 50%

Prac t ica l w ork in tw o p hases :Ph ase 1 (Wks 1-5) w o r k b o o kPh ase 2 (Wks 7-10) B rent , B oo k Cl i ffs

ENVS337

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Reading: text books

Basin Analysis (2005) , Allen and Allen,Blackwell Science. NEW EDITION OUT

Sequence Stratigraphy (1996) , Emery and

Myers, Blackwell Science.The sedimentary record of sea level change(2003) . Coe, A.L. Cambridge University Press.

Tectonic Geomorphology (2001), Burbank & Anderson, Blackwell Science.

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The main drive (or selling point)for research expertise in thehydrocarbon industry is to uncertainty. If we uncertaintywe profit. Simple.

AIM: To become familiar withthe methods / techniquesroutinely used by hydrocarboncompanies to alleviate thisuncertainty

ENVS337: reducing uncertainty

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ENVS337: HC exploration & recovery

Basin

Channel b eltf i l l

Channel &overbank

Facies & po respace

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ENVS337: anticipated outcomes

Familiarity with HC industryterminology and new disciplines(petrophysics, reservoir engineering).

Demonstrate how the hydrocarbon

industry (exploration and production)requires the geoscientist to integratediverse and interdisciplinary datasets.. to reduce uncertainty.

Provide the opportunity to applyyour academic knowledge (sequencestratigraphy, structure, geophysics) toreal-life problem solving.

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Basins: FormationWhat is a sedimentary basin?What drives sedimentary basin formation (initiation,duration and cessation)?What are the main types of sedimentary basins? Dodiagnostic patterns of sediment dispersal and

sedimentology exist?Death Valley

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Control of sea level fluctuations on the style ofsedimentary basin fillSource-to-Sink analysis of depositional systems,and the sediment routing conceptReal examples from surface & subsurface datasets

Basins: Filling

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The hydrocarbon play and the play fairwayRecoverable reserves, risk analysisPoro-perm, diagenesis, enhanced oil recovery

Basins: Resources

East Irish Sea Basin

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Basin analysis

Basin Analysis interrogates the formation, fill and subsequentdeformation of sedimentary basins, to provide a platform for theassessment of undiscovered hydrocarbon potential of an area,therefore guiding exploration programmes.

A few more

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Key themesBasin formation and dynamicsSubsidence patternsStructural geometryTopography & sediment routingSediment deposition

Hydrocarbon play

Som me and Jack son (2012)

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Basin analysis

Tecton ic se t t ing effects basin geometry and large scalestratigraphic architecture

Depo si t ional sys tems effect smaller scale stratigraphicvariations (e.g. alluvial fans, shelf, abyssal plain etc)

Basin analys is invo lves cons t ra in ing :Spatial and temporal pattern of sedimentaccommodationDepositional systemsSediment source areasSediment transport pathways

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Basin analysis: a range of toolsSubsurface (seismic,wireline) - PETRELSurface (ancient & modern)Geochronology (micro /macro palaeontology,

isotope geochemistry)Provenance (heavyminerals, isotope decay)Modelling (numerical,

stochastic, laboratory)A control on: sea-levelvariations, sedimentation rates,burial rates, sediment supplyrates, thermal history .

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What is a sedimentary basin?Basin :

A region of prolonged sedimentaccumulation generally causedby subsidence

Subs idence :Downward movement of asurface relative to some datum(e.g. sea level) generatingaccommodation

A c c o m m o d a t i o n :Space available for sediment tofill (in marine basin the regionbelow base-level)

Bifurcat ing grabens boun ded by l inkedfau l t segments in the Canyon lands (USA)

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Basin classification

(1) Proxim ity to p late bo un dary (margin,intracratonic)(2) Relative p late mo tion (tension, compression, transform(3) Li tho sph er ic posi t ion (continent, oceanic, transitional)

Many methods employed in the literature, generally based

on one or more of:

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The Wilson cycleIn the 1960 s J. TuzoWilson envisaged acycl ica l opening andclos ing of oceanicbas ins

1. Rif t in g

2. Spreadin g3. Init iat ion of

subduc t ion4. Basin clos ure

So over timebas ins mayt r ans fo rm f rom onetyp e to anotherAllen & Allen (2005)

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(1) Extens ion al (half g raben)

(2) Com press ion al (foreland basins )(3) Strike-sl ip basin s (trans fo rm )

Basin classification (3 main types)

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Subsidence mechanisms

Isos tasy changes in lithospheric thickness:Crustal thinning [Mechanical (stretching, erosion),Thermal]Crustal thickening [Underplating (accretion ofdense mantle material)]

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Subsidence mechanismsCrusta l Lo ad ing lithospheric deflection

Tectonic loading (Mountain building) Volcanic loading Sediment accumulation Water & ice

Mant le con vect ion Dynamic topography caused by mantleconvection (e.g. mantle plumes)

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Basin subsidence (and surface uplift)

Dis t inc t s ignature to bas in type Long -term sed iment accum ula tion Fi r s t o rder cont ro l on su ccess ions F ir s t o rder con t ro l on thermal h i s to ry

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Accommodation

A = E + S + C

A change in accommodation, A, is given as:

where E is eustasy, S is subsidence, C is compaction

the space madeavailable for s ediment toaccumulate isco ntrol led by base level ,s ince sed iment can on lyaccum ulate long te rm upto base level

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Why study basin successions?Ac ademic va lue

Decode the past movements of the Earths surfacein response to uplift and climatic regime (sedimentengine) and subsidence (sediment storage).

Basin successions represent a time - integratedarchive of Earth s surface dynamics

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Econom ic va lue

Vast accumulations of sediments that host HC reserves.If we have an understanding of how basins work, andapply our stratigraphic concepts, then we are in a better

position to predict where and when hydrocarbons

accumulated (i.e. reduce our uncertainty)

Why study basin successions?

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Hydrocarbon systems are

comprised of a series of elementsand processes that together enablethe generation, migration andentrapment of hydrocarbons atvarious stratigraphic levels within a

sedimentary basin fill. Elements of the hydrocarbon

system include source, reservoir,seal and trap.

Processes operating withinhydrocarbon systems includehydrocarbon generation, expulsionand migration, as well as fluid flow,

pressure and temperature related processes.

The hydrocarbon play is a perception or model of howelements and processes interactthrough time to generate ahydrocarbon accumulation.

The hydrocarbon play: brief intro

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Reservoir unit capable of storing hydrocarbons and capable

of yielding them to the well bore at commercial rates.Hydrocarbon charge system comprises thermally mature

petroleum source rocks capable of expelling hydrocarbons into porous and permeable carrier beds, which transport them

towards sites of accumulation (traps) in the reservoir unit.Regional top seal a cap rock to the reservoir unit containingthe hydrocarbons.

Hydrocarbon traps concentrate the hydrocarbons in

specific locations, allowing exploitation.

Hydrocarbon play: elements & processes

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Timing & time/duration: the abo ve 4 ing redientsneed to b e p resen t w i th in the bas in a t speci f ic t imes .For examp le a t rap n eeds to h ave fo rm ed p r io r tohyd rocarbon s b e ing expel led f rom the sourc e etc .

Hydrocarbon play: elements & processes

Common senseperhaps .... but

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Play fairway the geographic limitsof the hydrocarbon play.

Proven play hydrocarbonaccumulations are known to haveresulted from the operation of thegeological factors that define theplay.

Unproven play doubt as towhether the geological factorsreally do combine to produce ahydrocarbon accumulation.

The hydrocarbon play fairway

Example of a Play map

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Accurate prediction of the behaviour of the hydrocarbon play isdependent on understanding the structural and stratigraphicevolution (temporal and spatial) of a sedimentary basin basin.

The hydrocarbon play: brief intro

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Practical 1: Stratigraphic relationships fromseismic and well data [tomorrow @ 1000-1300]

Seismic interpretation offshore Utopesia

WEEK S 1-5: The aim of these practical sessions is to providegrounding in the techniques routinely used by geologists working inthe exploration sector of the HC in their search for hydrocarbonreserves. NOTE: Practicals 1-5 form an integrated series.

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L o catio n : CTL-5-ENV

Micr o sc o p es/Env. Sci . lab, ro o m 110

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