PETROLEUM SYSTEM.pptx

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PETROLEUM SYSTEM COMPONENTS

Source Rock Generation(Maturity)

Migration Path

Trap

Reservoir Rock

Seal (Cap Rock)



Petroleum System Section



Petroleum System Section



SOURCE ROCK HYDROCARBON GENERATION

The formation of hydrocarbon liquids from anorganic rich source rock with kerogen and bitumento accumulates as oil or gas.

Generation depends on three main factors:

the presence of organic matter rich enough to

yield hydrocarbons

adequate temperature

and sufficient time to bring the source rock tomaturity

pressure and the presence of bacteria andcatalysts also affect generation

generation is a critical phase in thedevelopment of a petroleum system



SOURCE ROCK CHARACTERISTICS

Fine grained sediments, usually shale orlimestone, rarely coal

Must contain sufficient amounts of organicmatter (>0.5 % TOC, generally 2-15 %)

Organic matter must be relatively rich inhydrogen

– hydrogen rich = oil prone

– hydrogen lean = gas prone

Rocks must be buried deep enough tothermally transform organic matter to

liquid or gas

Generated petroleum must migrate out of the

source rock



ORIGIN OF MATERIAL

Terrestrial material

The type of material is difficult to determine but

several apparent patterns have been noticed.

•

Ocean or lake material often meet kerogen type IIIor IV classifications.

•Ocean or lake material deposited under anoxic

conditions often form kerogens of type I or II.

•

Most higher land plants produce kerogens of type IIIor IV.

•Some coal contains type II kerogen.



Extraterrestrial material

Carbonaceous chondrite meteorites contain

kerogen-like components. Such material isbelieved to have formed the terrestrial

planets.

Kerogen materials have been detected in

interstellar clouds and dust around stars.

Generally Type I is strongly oil prone,

Type II is oil and condensate prone while

Type III is gas prone. Type IV is generally

non productive.



Organic Mater Paragenesis



MIGRATION The movement of hydrocarbons from their source into reservoir

rocks.

The movement of newly generated hydrocarbons out of their

source rock is primary migration, also called expulsion.

The further movement of the hydrocarbons into reservoir

rock in a hydrocarbon trap or other area of accumulation

is secondary migration.

Migration typically occurs from a structurally low area to

a higher area in the subsurface because of the relative

buoyancy of hydrocarbons in comparison to the surrounding

rock.

Migration can be local or can occur along distances of

hundreds of kilometers in large sedimentary basins, and is

critical to the formation of a viable petroleum system



Definitions Of Primary and Secondary

Migration

(After Tissot and Welte, 1984)



ACCUMULATION

The phase in the development of a

petroleum system during which

hydrocarbons migrate into and remain

trapped in a reservoir.



TRAP





An impermeable rock that acts as a barrier tofurther migration of hydrocarbon liquids.

Rocks that forms a barrier or cap above andaround reservoir rock forming a trap such

that fluids cannot migrate beyond the

reservoir.The permeability of a seal capable of

retaining fluids through geologic time is ~10-6 to 10-8 darcies. commonly:

shale, mudstone

anhydrite

salt

A seal is a critical component of acomplete petroleum system.

SEAL CAP ROCK)







Th k F Y Att t



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PETROLEUM SYSTEM.pptx

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