apg d2a petroleum systems.pdf

11

Day 2: The Petroleum Day 2: The Petroleum

PlayPlay

. and why the Petroleum System . and why the Petroleum System

concept is so important. concept is so important.

22

Special Acknowledgement & ReferenceSpecial Acknowledgement & Reference

Special thanks to John Armentrout of the American Special thanks to John Armentrout of the American Association of Petroleum Geologists for helping Association of Petroleum Geologists for helping provide some of the Petroleum Systems material provide some of the Petroleum Systems material used in this introduction. John did this work on behalf used in this introduction. John did this work on behalf of the AAPGof the AAPGs s Visiting GeologistVisiting Geologist program.program.

AAPG Memoir 60, AAPG Memoir 60, The The Petroleum System Petroleum System -- from Source to from Source to TrapTrap, edited by Leslie Magoon & Wallace Dow and AAPG , edited by Leslie Magoon & Wallace Dow and AAPG Methods in Exploration #7, edited by Wagoner, Mitchum, Methods in Exploration #7, edited by Wagoner, Mitchum,

Campion & Rahmanian are recommended for further reading.Campion & Rahmanian are recommended for further reading.

33

Petroleum System DefinitionPetroleum System Definition

Source RockSource Rock

Migration RouteMigration Route

Reservoir RockReservoir Rock

Seal RockSeal Rock

TrapTrap

ElementsElements

GenerationGeneration

MigrationMigration

AccumulationAccumulation

PreservationPreservation

Timing Critical!Timing Critical!

ProcessesProcesses

The essential elements and processes and all The essential elements and processes and all geneticallygenetically--related hydrocarbons that occur in related hydrocarbons that occur in petroleum shows, and accumulations whose petroleum shows, and accumulations whose

provenance is a single pod of active source rock.provenance is a single pod of active source rock.

44

24803


Top Seal RockTop Seal Rock


Anticlinal TrapAnticlinal Trap

(Organic Rich)(Organic Rich)

(Impermeable)(Impermeable)

(Porous/Permeable)(Porous/Permeable)

PotentialPotentialMigration RouteMigration Route

Petroleum System ElementsPetroleum System Elements

55

Petroleum System ElementsPetroleum System Elements

Source Rock: Source Rock: a rock with abundant hydrocarbona rock with abundant hydrocarbon--prone prone organic matterorganic matter

Reservoir Rock:Reservoir Rock: a rock in which oil and gas accumulates: a rock in which oil and gas accumulates:

-- Porosity; space between rock grains in which oil & gas Porosity; space between rock grains in which oil & gas accumulatesaccumulates

--Permeability; ease with which oil & gas can move Permeability; ease with which oil & gas can move through the pore space between the grains through the pore space between the grains

Seal Rock:Seal Rock: a rock through which oil and gas cannot move a rock through which oil and gas cannot move effectively (such as mudstone or effectively (such as mudstone or evaporiteevaporite), over time!), over time!

Migration Route:Migration Route: avenues through which oil and gas move avenues through which oil and gas move from source rock to trapfrom source rock to trap

Trap:Trap: the structural and stratigraphic configuration that the structural and stratigraphic configuration that focuses oil and gas into an accumulationfocuses oil and gas into an accumulation

66

The Origin of PetroleumThe Origin of Petroleum

OrganicOrganic--richrichSource RockSource Rock

Thermally MaturedThermally MaturedOrganic MatterOrganic Matter OilOil

77

Kerogen TypesKerogen Types

TOC 2.12 WT.% TOC .38 WT.%

**

* Or plankton (* Or plankton (lacustrinelacustrine or marine)or marine)

****

** Or marshy, swampy, peat bogs** Or marshy, swampy, peat bogs

88

Types of PetroleumTypes of Petroleum

Oil and gas are formed by the thermal Oil and gas are formed by the thermal cracking of organic compounds buried cracking of organic compounds buried in finein fine--grained rocks.grained rocks.

Algae* = Hydrogen rich = OilAlgae* = Hydrogen rich = Oil--proneprone

Wood = Hydrogen poor = GasWood = Hydrogen poor = Gas--proneprone

* Also plankton, or waxy cuticles/spores of tropical land plants* Also plankton, or waxy cuticles/spores of tropical land plants

99

Reservoir SandstoneReservoir Sandstone

Good Porosity = Lots of Space for PetroleumGood Porosity = Lots of Space for Petroleum

Pores(blue)

1010

Reservoir SandstoneReservoir SandstonePorePore--Filling Cement Reduces QualityFilling Cement Reduces Quality

= Less Space for = Less Space for PetroleumPetroleum

CementCement(pink)(pink)

1111

Pore Types Pore Types -- SandstonesSandstones

The Good

The Bad

The UGLY

1212

TrapsTraps

AnticlinalAnticlinal -- Rock layers folded into a domeRock layers folded into a dome

FaultFault -- Offset of rocks such that oil and gasOffset of rocks such that oil and gasaccumulates in reservoir rockaccumulates in reservoir rock

StratigraphicStratigraphic -- Rock layers changing from a Rock layers changing from a good reservoir to a nongood reservoir to a non--reservoir seal, due to reservoir seal, due to change in rock type (pinchchange in rock type (pinch--out), reservoir out), reservoir quality (diagenesis), or removal (erosional quality (diagenesis), or removal (erosional unconformity)unconformity)

1313American Petroleum Institute, 1986American Petroleum Institute, 1986

Salt DomeFault

Unconformity

Pinchout

Anticline

Hydrocarbon Trap TypesHydrocarbon Trap Types-- which are the best prospects?which are the best prospects?

1414

24803

120 F120 F

350 F350 FGenerationGeneration

MigrationMigration

Seal RockSeal Rock

ReservoirRockReservoirRock

OilOil

WaterWater

Gas CapGas Cap

EntrapmentEntrapment

Source RockSource Rock (50(5000C)C)

(175(17500C)C)

AccumulationAccumulation

Petroleum System ProcessesPetroleum System Processes

1515

Petroleum System ProcessesPetroleum System Processes

GenerationGeneration -- Burial of source rock to temperature and Burial of source rock to temperature and pressure regime sufficiently long to convert organic pressure regime sufficiently long to convert organic

matter into hydrocarbon {early/late}matter into hydrocarbon {early/late}

MigrationMigration -- Movement of hydrocarbon out of the sourceMovement of hydrocarbon out of the source

rock toward and into a trap {primary /secondary}rock toward and into a trap {primary /secondary}

AccumulationAccumulation -- A volume of hydrocarbon migrating into a A volume of hydrocarbon migrating into a

trap faster than the trap leaks resulting in an trap faster than the trap leaks resulting in an

accumulationaccumulation

PreservationPreservation -- Hydrocarbon remains in reservoir; is not Hydrocarbon remains in reservoir; is not

biodegraded/contaminated nor the trap breachedbiodegraded/contaminated nor the trap breached

and do not forget and do not forget TimingTiming -- Trap forms before and during Trap forms before and during

hydrocarbon migrationhydrocarbon migration

1616

Oil & Gas GenerationOil & Gas Generation

Vitrinitereflectance

1717

Spill PointSpill Point

Seal Rock(Mudstone)Reservoir Rock

(Sandstone)Migration fromKitchen

1) Early Generation

2) Late Generation

Gas displaces all

oil

Gas beginning to displace oil

Displaced oil

accumulates

Petroleum SystemPetroleum SystemA Dynamic Entity

1818

DeerDeer--Boar Petroleum System Boar Petroleum System

at Critical Momentat Critical Moment

TeapotOwens

Pod of Active

Source Rock Just

Big Oil

Hardy Lucky

Zero Edge of

Reservoir Rock

Immature Source Rock

Raven

Marginal

250 Ma

A A

Magoon and Dow, 1994Magoon and Dow, 1994

Res

ervo

ir R

ock

David

1919

Overburden

Seal

Reservoir

Source

STRATIGRAPHICSTRATIGRAPHIC

EXTENT OFEXTENT OF

PETROLEUM SYSTEMPETROLEUM SYSTEM

Trap Trap

Essential

elements of

petroleum

systemPOD OF ACTIVE

SOURCE ROCK

Base

men

t

Underburden Se

dim

en

tary

ba

sin

-fil

l

GEOGRAPHIC EXTENT OF PETROLEUM SYSTEM

250 MaTrap

Petroleum accumulation

Top of oil window

Bottom of oil window

Location for burial history chart

A A

Petroleum System at Critical MomentPetroleum System at Critical MomentCritical Moment = Time of Expulsion/MigrationCritical Moment = Time of Expulsion/Migration


2020

Base

men

t

GEOGRAPHIC EXTENT OF PETROLEUM SYSTEM

Present-Day

STRATIGRAPHIC

EXTENT OF

PETROLEUM SYSTEM

Petroleum accumulation

Top of oil window

Bottom of oil window

Trap TrapTrap

Seal

Reservoir

Source

Underburden

Overburden

A A


PresentPresent--Day Petroleum SystemDay Petroleum System

2121

400400 300300 200200 100100

PaleozoicPaleozoic MesozoicMesozoic Cen.Cen.

PP NNKKJJTPPMMDD PP Litholo

gy

Litholo

gy

RockRock

UnitUnit

Depth

(K

m)

Depth

(K

m)

Sourc

eS

ourc

e

Rese

rvoir

Rese

rvoir

Seal

Seal

Overb

urd

en

Overb

urd

en

11

22

33

Placer FmPlacer Fm

George ShGeorge Sh

Boar SsBoar Ss

Deer ShDeer Sh

Elk FmElk Fm

Top gas windowTop gas window

Critical MomentCritical Moment

ThickThick

FmFm

RR

Burial History ChartBurial History Chart


GenerationGeneration

Time of Expulsion and Migration. (Trap must already exist)Time of Expulsion and Migration. (Trap must already exist)

Top oil windowTop oil window

2222

400400 300300 200200 100100 Geologic TimeGeologic Time

ScaleScale

PetroleumPetroleum

System EventsSystem Events

Rock UnitsRock Units



Seal RockSeal Rock

Trap FormationTrap Formation

Overburden RockOverburden Rock

Gen/Migration/AccumGen/Migration/Accum

PreservationPreservation


PaleozoicPaleozoic MesozoicMesozoic CenozoicCenozoic

DD MM PP PP TTRR JJ KK PP NN

Ele

me

nts

Ele

me

nts

Pro

ce

ss

es

Pro

ce

ss

es


Petroleum System Events ChartPetroleum System Events ChartTiming of Elements and ProcessesTiming of Elements and Processes


Time of Expulsion and Migration. (Trap must already exist)Time of Expulsion and Migration. (Trap must already exist)

2323

ExerciseExercise

Draw a Petroleum Systems Events Chart Draw a Petroleum Systems Events Chart

in your subin your sub--basin and discuss risking the basin and discuss risking the

various elements of the system. various elements of the system.

2424

Play Concept Play Concept

MapMap

Eliminate areas with no: Structures (or strat traps) Effective reservoir Effective seals Inaccessible to migration from mature source rocks Where traps post-date the timing of Migration

Risk prospects using probabilities!Risk prospects using probabilities!

2525

Probability (Risk) AssessmentProbability (Risk) Assessment

Pplay = Psource x Preservoir x Ptrap x Pseal x Ptiming*

* Timing (& direction) of migration versus development of trap

Note different companies may use different criteria internally to assess prospects

Exploration is risky: with an 85% probability of success in each

element, the combined probability is under 50%.... Multiply it out!

2626

SummarySummary

The Petroleum Systems concept allow us to: The Petroleum Systems concept allow us to:

-- Systematically evaluate the quality of the different Systematically evaluate the quality of the different

elements (source, reservoir, seal, trap & migration elements (source, reservoir, seal, trap & migration

pathways) of the stratigraphic modelpathways) of the stratigraphic model

-- Critically analyse the timing of migration, accumulation Critically analyse the timing of migration, accumulation

and the chances of preservation of hydrocarbons.and the chances of preservation of hydrocarbons.

apg d2a petroleum systems.pdf

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