basin and petroleum systems modeling

7/30/2019 Basin and petroleum systems modeling

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R. Blakey Cretaceous Paleogeography


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Petroleum Systems


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Basin & Petroleum Systems Modeling


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Petroleum System Definitions

What is a Petroleum System? (** Emphasis is on

conventional petroleum systems!)

A Petroleum System is defined as a natural system

that encompasses a pod of active source rock and all

related oil and gas which includes all of the geologic

elements and processes that are essential if ahydrocarbon accumulation is to exist. Magoon and Dow, 1994

Slides courtesy of Matthias Greb, Apache


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Petroleum

A mineral oil occurring in subsurface rocks and at the surface which is a naturally

occurring mixture of hydrocarbon and non-hydrocarbon compounds. It may occur

in the gaseous, liquid, or solid state depending on the nature of these compounds

and the existent conditions of temperature and pressure. Common synonyms are

hydrocarbons and oil and gas.

System

A regularly interacting or interdependent group of items forming a unified whole

whose organization forms a network for distributing something, for example;

telephone, highway, blood, or petroleum.



(after Magoon and Dow, 1994)


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Source Rock

A rock unit containing sufficient organic matter (kerogen) of suitable chemical

composition to biogenically or thermally generate and expel petroleum.

Pod of Active Source RockA contiguous volume of source rock that is generating and expellingpetroleum at the

critical moment and is the provenance for a series of genetically related petroleum

shows, seeps, and accumulations in a petroleum system. A pod of mature source rock

may be active, inactive or spent.

Reservoir Rock

A subsurface volume of rock that has sufficient porosity and permeability to permit

the migration and accumulation ofpetroleum under adequate trapconditions.


Petroleum System Source / Reservoir / Seal / Overburden (+trap)



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Petroleum System Source

Rock Eval + Pyrolysis

-Source type

and maturity


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Petroleum System Reservoir


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Seal

A shale or other imperviousrock that acts as a barrier to the passage of petroleum

migrating in the sub-surface; it overliesthe reservoir rock to form a trap or conduit.

Also known as roof rock and cap rock.

Overburden Rock

The sedimentary rock above which compresses and consolidates the material

below. In a petroleum system the overburden rock overlies the source rock and

contributes to its thermal maturation because of higher temperatures at greater

depths.


Petroleum SystemSeal / Overburden



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2 Processes are essential for a working Petroleum System

Trap Formation (structural evolution or stratigraphic framework)

GenerationMigration Accumulation


Petroleum System Petroleum System Elements


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Petroleum System Traps


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from TISSOT & WELTE (1984)


Petroleum System Migration

(Expulsion)


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Why do hydrocarbons migrate?

Fluids migrate along a pressure gradient

pressure driven

Density contrasts between hydrocarbons and water

buoyancy driven

Diffusion due to concentration differences

chemical gradient driven

Hydrocarbons migrate as a separate phasefrom the higher potential to a lower potential

via the most efficient way

topography driven

How do hydrocarbons migrate?



Generated HC Massesfrom Source

Topography driven

buoyancy driven

fromHantschel&Kauerauf(2009)

cpwwp phguu )(

Overpressure Buoyancy Capillary Pressure


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Migration Mechanism Migration Rate

Hydrodynamic (pressure driven) 10-3 to 1000 m/a

Compaction (drainage) 10-5 to 1 m/a

Buoyancy Meters per day (gas)Diffusion 1 to 10 m / Ma

Petroleum Migration Rates



Fluid velocity [m/a]

1 10 102 103 1040.110-210-410-510-610-7 10-3

Buoyancy GAS

Hydrodynamic?

?Compactionally driven flow

Diffusion


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5000m

4500m

2500m

2000m

3000m

2000m

2500m

BA C

A

A


Hydrocarbons migrate as a

separate phase from the

higher potential to a lowerpotential on the direct way,

usually from the deepest to

the shallowest part of the

basin, depending on the

drainage area.

1) Identify the drainage area

for trap A, B & C

2) Draw the hydrocarbon flow

lines towards each trap

1500

2000

2500

3000

3500

4000

4500

5000

A A

Petroleum SystemExercise


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5000m

4500m

2500m

2000m

3000m

2000m

2500m

BA C


Petroleum System Migration - Exercise


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BA C

Petroleum System Migration - Solution


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Geographic Extent

The area over which the petroleum system occurs, defined by a line that

circumscribes the pod of active source rock as well as all the discovered petroleum

shows, seeps, and accumulations that originated from that pod. The geographic

extent is mapped at the critical moment. Also the known extent.

Burial History Chart

A burial history curve or geohistory diagram constructed to show the time over which

hydrocarbon generation occurs. Depicts the essential elements and the critical

moment for the petroleum system.

Events Chart

A chart for a petroleum system showing when the essential elements and processes

took place as well as the preservation time and critical moment of the system.





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Critical Moment

The time that best depicts the generation migration accumulation of

hydrocarbons in a petroleum system. A map and a cross section drawn at the critical

moment best shows the geographic and stratigraphic extent of the System.

The four elements Source Rock, Reservoir Rock, Seal Rock and a sufficient Amount of

Overburden have to be in place before the Critical Moment.


Petroleum System Age

The time over which the process of generation-migration accumulation of

hydrocarbons in the system takes place on the events chart.

Preservation Time

The time after generation-migration-accumulation of petroleum takes place and

encompasses any changes to the petroleum accumulations up to present day.

Petroleum System Timing!



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Deer Boar Petroleum System

@ 250 Ma -> Critical Moment:

generation started

traps exist

migration possiblePod of Active

Source Rock

Reservoirs

A-A Cross Section


(from Magoon and Dow, 1994)

Geographic Extent


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Burial Chart

Events Chart

Deer Boar Petroleum System

@ 250 Ma -> Critical Moment:

generation started

traps exist

migration possible


(from Magoon and Dow, 1994)

Combined with Events Chart


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Follow the below listed instructions to analyze the Paris Basin petroleum system

1. Draw a line (map) around the pod of active source rock (green-colored pencil).

2. Draw a line (map) around the geographic extent of the petroleum system (red-colored pencil).

3. Draw a line (map) of cross-section on the map (brown-colored pencil) that

would best show the relation of the pod of active source rock to the petroleum

migration paths and accumulations.

4. Draw an asterisk on the map (brown-colored pencil) where a burial history

chart would best show the onset and end of petroleum generation and the

critical moment.

5. Draw a few arrows (green-colored pencil) to indicate the directions of oil and

gas migration.

PARIS BASIN Petroleum System Analysis


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Pod of active source rock

Geographic extent

Cross section location

Burial history chart location

Petroleum migration



Use the following symbols to analyze the

Paris Basin Petroleum System


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Paris Basin, from Tissot & Welte, 1978


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Paris Basin, from Tissot & Welte, 1978


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Petroleum Systems Model

APetroleum Systems Modelis a digital data model of

an entire petroleum system in which the interrelated

processes and their results can be simulated in order to

understand and predict them.

The model is dynamic and provides a complete record

through geologic time.

from Magoon and Dow, 1994


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Key Questions and Tasks of Petroleum Systems ModelingPetroleum Generation

Have hydrocarbons been generated?

Resource assessment studies and initial charge risking. There are basins in which no oil and gashave been generated!

Where were hydrocarbons generated?

If hydrocarbons were generated, we can define their locations quite accurately.

When were hydrocarbons generated?

There are many clear examples of where basins/plays/prospects have failed due to timingproblems. For example, when oil and gas was generated early and the structures were createdmuch later:

Petroleum Migration & AccumulationCould they have migrated to the prospect?Modeling of the dynamic process of generation, expulsion and migration makes it possible todetermine if the oil and gas charge could reach the trap.

What are the properties of the hydrocarbons?Modeling of the phase behaviour of the hydrocarbons during migration, accumulation and lossmakes it possible to determine oil vs. gas probabilities and even predict properties such as API

gravities and GORs.


Petroleum Systems Model


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Allen, P.A. & Allen, J.R. (2005): Basin Analysis: Principles and Applications, Blackwell Science, Malden, MA, USA; 560pp.

Hantschel, T., Kauerauf, A.I. (2009): Fundamentals of Basin Modeling, Springer Verlag, Berlin, Germany, 476pp

Magoon, L.B. & Dow, W.G. (1994): The Petroleum System from Source to Trap, AAPG Memoir 60, Tulsa, OK, USA; 655pp.

Tissot, B.P. & Welte, D.H. (1984): Petroleum Formation and occurrence. 2ndEdition, Springer Verlag


Petroleum System - References


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F W Schroeder 04 L 1 - Focus of IndustryCourtesy of ExxonMobil

A Fully-Integrated Oil Company

Getting RefinedProducts to

the Consumers

Getting RawOil & Gas tothe Refinery

Refinery

http://www.npl.co.uk/upload/img_400/oilrig.gif


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Components of the Upstream

How to Get It Out where, in detail, are the reserves?

what to build (facilities)?

will it be profitable?

Find Oil & Gas Pools which regions and basins?

which blocks?

where on the block?

From the Ground, to the Refinery how to manage the field?

how to deliver the crude?


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Oil Company Targets

To maintain a healthy petroleum company,one would want to:

Replace production (what you take out of the

ground) with new reservesExploration Finds Volumes Produced

Keep finding costs below $1 per barrel

Exploration Costs

New Barrels< $1/barrel


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We Need to Drill Wisely

Wells can be very expensive, some many hundreds

of millions of dollars, a lot even for a major oilcompany

Well placement and well path can be critical to

success So ..

How can we determine where to drill and predictwhat we will find BEFORE we start drilling?

This leads to the need for geologists,geophysicists, and other specialists focused on

imaging and interpreting the subsurface


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Explorations Task

SuccessUneconomic

Drill

Wildcats

Assess

Prospects

DropProspect

Confirmation

Well

SuccessFailureInterpret

Seismic Data

ProcessSeismic Data

Acquire

Seismic Data

Capture

Prime Areas

Identify

Opportunities

To DevelopmentOr Production


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An Exploration Success

The Bonanza Basin, offshoreSomewhereia, was deemedto have high potential.

We leased the two highest-ranked blocks in the lastlicensing round.

Block

1

Block

5

Block

4

Block

3Block

2

Block

8

Block

7Block

6

Somewhereia

Bonanza Basin


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The Bonanza Basin, offshoreSomewhereia, was deemedto have high potential.


8 leads were identified, 3passed economic screeningand were matured intoprospects.

Bonanza Basin

Block

8

Block

7

Lead

A

Lead

B

Lead

C

Block

8

Block

7

Alpha Prospect

l i S


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The Bonanza Basin, offshoreSomewhereia, was deemed

to have high potential.



We drilled a wildcat at the

Alpha Prospect & found oil.

Alpha Prospect

Block

7

Bonanza Basin

DiscoveryWellBlock

8

SaltDiapir

A E l i S


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The Bonanza Basin, offshoreSomewhereia, was deemed

to have high potential.



We drilled a wildcat at the

Alpha Prospect & found oil.

A confirmation well provedthat there are significantvolumes of oil.

Alpha FIELD

EUR = 200 MBO

.95 TCF

Block7

Bonanza Basin

DiscoveryWell

ConfirmationWell

Block

8

SaltDiapir

Our estimate of ultimaterecovery is 200 MBO.

G&G i D l t


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G&G in Development

Can we refine our picture of the distribution of oil

at Alpha?

Is the reservoir a single unit, or is it segmented(separate regions to drain)?

How many wells/where should they be drilled?

What sort of facilities (platform?) will we need?

How can we speed-up time to first oil?

What uncertainties remain?

Exploration has drilled a discovery and a confirmation well.

The ultimate recover for Alpha is estimated to be 200 MBO,which greatly exceeds the economic threshold of 100 MBO

Questions:

W N d M D t il


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We Need More Detail

Reservoir Mapat the end ofExploration

Reservoir Mapat the end ofDevelopment

W M N d B tt D t


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We May Need Better Data

Data Used for Exploration

Data Reprocessed or

Reshot for DevelopmentAnd Production

G&G i P d ti


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G&G in Production

How should we manage the field so as to maximizeour investments?

Can we monitor how oil is being swept out of thereservoir?

What about injection wells and enhanced recovery?

Is there more oil in the vicinity either at deeper

depths or in nearby traps?

Can we build a computer model of the field thatmatches existing production data? If so, we can testfuture recovery with different drilling scenarios.

Production has begun at Alpha.

The initial production rates are as expected.

Questions:

R i Si l ti


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Reservoir Simulation

Geologic Model

Reservoir Simulation

OilProduction

Time

HISTORY

MATCH

Th V l f G&G t Oil C


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The Value of G&G to an Oil Company

G&G work is done to add HC reserves(volumes)

New discoveries

More from discovered producing zones

Additional producing zones

Get the most reserves at the lowest cost

Invest in the right basins

Drill in the optimum locations Correctly assess what can be recovered

Avoid unnecessary wells

basin and petroleum systems modeling

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