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PETROLEUM SYSTEM:MIGRATION & ACCUMULATION - Coggle Diagram
PETROLEUM SYSTEM:MIGRATION & ACCUMULATION
oil and gas migration
subsequent hydrocarbons within to reservoir = oil and gas left the source rock and move to reservoir
hydrocarbons buoyancy caused by differences densities of each fluids and they response to differential pressures in reservoir rock
3 evidence that shows hydrocarbons migration to reservoir rock some depth and time
oil & gas are trapped at the highest point in a permeable rock unit as fluid always going upward
oil, gas, and water occur together in a stratified porous and permeable reservoir rock. this require migration path
oil and gas occur in soluble pores and fractures in reservoir rock
principle of migration
migrate in different phase due to buoyancy
move vertically upward due to forces
oil and gas migration is secondary migration
migration stages
secondary migration
carrier bed to trap
movement of fluids within reservoir rock
result of buoyant and hydrodynamic process
possibilities of mixing by other petroleum from other source rock
possibilities of physical, chemical and bacteria alteration (affect petroleum quality)
migrate through fracture, faults, unconformities and continuous sand until encounter seal rock
large distance
tertiary migration
trap-fresh trap-seepage
movement of oil and gas after formation of accumulation
buoyancy drives the petroleum to the surface
process that lead to tertiary migration: trap failure, through capillary leakage, hydraulic fracture
primary migration
expulsion of petroleum the source rock
movement from fine grained source rock to coarse grained reservoir rock
source rock to carrier bed
short distance
oil and gas accumulation
forms when migrating hydrocarbon encounter a zone which is the seal
form in traps and seal rock
oil and gas accumulation is caused by primary migration and short-distance secondary migration
commonly not controlled by anticline traps, but largely by non-anticline traps, especially lithological traps
accumulation principle derived buoyancy which gas and oil more light than water and place them at the top
petroleum trap
may contain oil, gas and water
oil water contact (OWC) which the deepest point of the oil can be removed
GOC and GWC which the lowest limit of production
petroleum alteration
physical and chemical condition of the accumulation in the reservoir changed (due to biodegradation)
effect petroleum composition
affect oil density
change in petroleum composition based on a reservoir pressure release
from source rock only 10% from petroleum use to economical
40% from earlier expelled that will accumulate
10% from accumulation will lost through leakage
50% from petroleum will enter carrier bed
25% from accumulation lost through alteration
75% expelled in primary migration
Starting from the source rock where they are formed, hydrocarbon molecules, which are light, set off on an upward journey to the surface. They accumulate in porous rock and are blocked by impermeable rock, thereby creating oil and gas deposits
In the source rock, preservation (hydrocarbons) are present in greater volumes under higher pressures than the initial kerogen .
Little by little, they are expelled into the water-containing rocky layers located adjacent to the source rock.
Because hydrocarbons are lighter than water, gas and oil rise upward by circulating between the mineral grains of the rock.
This slow, constant movement away from the source rock is called migration (hydrocarbons)
migration rate depends on the permeability of the rocks they cross and the size of the molecules.
gas molecules rise more quickly than oil molecules, because they are smaller and more mobile.
Some hydrocarbon molecules are prevented from moving upward, either because they dissolve in the water contained in the rock they encounter
emplacement
changes in reservoir like leakage of water or gas in