apg d2a petroleum systems.pdf
TRANSCRIPT
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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.
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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.
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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.
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Source RockSource Rock
Top Seal RockTop Seal Rock
Reservoir RockReservoir Rock
Anticlinal TrapAnticlinal Trap
(Organic Rich)(Organic Rich)
(Impermeable)(Impermeable)
(Porous/Permeable)(Porous/Permeable)
PotentialPotentialMigration RouteMigration Route
Petroleum System ElementsPetroleum System Elements
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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
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The Origin of PetroleumThe Origin of Petroleum
OrganicOrganic--richrichSource RockSource Rock
Thermally MaturedThermally MaturedOrganic MatterOrganic Matter OilOil
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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
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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
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Reservoir SandstoneReservoir Sandstone
Good Porosity = Lots of Space for PetroleumGood Porosity = Lots of Space for Petroleum
Pores(blue)
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Reservoir SandstoneReservoir SandstonePorePore--Filling Cement Reduces QualityFilling Cement Reduces Quality
= Less Space for = Less Space for PetroleumPetroleum
CementCement(pink)(pink)
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Pore Types Pore Types -- SandstonesSandstones
The Good
The Bad
The UGLY
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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)
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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?
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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
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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
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Oil & Gas GenerationOil & Gas Generation
Vitrinitereflectance
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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
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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
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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
Magoon and Dow, 1994Magoon and Dow, 1994
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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
Magoon and Dow, 1994Magoon and Dow, 1994
PresentPresent--Day Petroleum SystemDay Petroleum System
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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
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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
Magoon and Dow, 1994Magoon and Dow, 1994
GenerationGeneration
Time of Expulsion and Migration. (Trap must already exist)Time of Expulsion and Migration. (Trap must already exist)
Top oil windowTop oil window
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400400 300300 200200 100100 Geologic TimeGeologic Time
ScaleScale
PetroleumPetroleum
System EventsSystem Events
Rock UnitsRock Units
Source RockSource Rock
Reservoir RockReservoir Rock
Seal RockSeal Rock
Trap FormationTrap Formation
Overburden RockOverburden Rock
Gen/Migration/AccumGen/Migration/Accum
PreservationPreservation
Critical MomentCritical Moment
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
Magoon and Dow, 1994Magoon and Dow, 1994
Petroleum System Events ChartPetroleum System Events ChartTiming of Elements and ProcessesTiming of Elements and Processes
Critical MomentCritical Moment
Time of Expulsion and Migration. (Trap must already exist)Time of Expulsion and Migration. (Trap must already exist)
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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.
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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!
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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!
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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.