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Reservoir, Seal and Trap - Coggle Diagram
Reservoir, Seal and Trap
Reservoir
Characteristics
High
porosity =
High
hydrocarbon hold
Low
permeability =
Low
chance for liquid / gas to flow
2 types:
Conventional
Oil / Gas trap by overlying rock
Under
low
permeability
Unconventional
No need cap rock
Already in
high porosity
and
low permeability
Trap
Form by
buoyancy forces
driving the upward migration of hydrocarbon
3 types:
Structural trap
Form in
deformed strata
Example:
Fold
Fault
Salt dome
Stratigraphic trap
Example:
Unconformities
Pinch-outs
Reef
Form at where
rock type change
Combination
Combination of structural and stratigraphic / others trap
Horizon contact between medium exist
GOC = Gas-Oil Contact
GWC = Gas-Water Contact
May form tilt contact, due to:
Hydrodynamic flow
Production
Slope of the trap
Tar formation
Consist with bacteria
Low quality
Occur at GWC
Facies change
Timing
of trap formation is important
Should be form first before oil and gas generate
If formation late:
Pore water will form
Bacteria exist
Low quality of oil produce
Seal
Form when
capillary pressure is high / equal to buoyancy pressure
of migrating hydrocarbon
Prevent fluids to flow
upward and escape
2 type:
Membrane seal
hydraulic seal
Impermeable
Commonly made up by
shale layer
Fine grain
Impermeable
Effectiveness
Lithology
Ductility
Elasticity should be high especially at active tectonic area
Thickness
High thickness. High effectiveness
Lateral continuity
Accumulation cannot occur if the continuity absent
Burial depth
Not to important
Petroleum alteration
Physical and chemical
accumulation in reservoir change
Causes
Biodegradation
Thermal alteration
Others:
Alteration of asphaltine