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Migration and Accumulation - Coggle Diagram
Migration and Accumulation
Oil and Gas Migration
3 types
Primary
Movement of hydrocarbon from source rock to reservoir rock
Short distance
Expulsion of petroleum (oil) occur cause by buoyancy force
Secondary
Movement of hydrocarbon from reservoir rock to trap (till the cap rock form)
Occur cause by buoyant and hydrodynamics
Possibilities of alteration cause by water, upon:
Physical
Chemical
Bacterial
High permeability leads to high migration
Process stop:
Impermeable barriers / Seal / Cap form
Long distance
Tertiary
Movement of oil and gas after formation of recognizable accumulation
Occur due to the trap failure, cause by:
Fracture
Tectonic
Thin layer of cap rock
High pressure
The oil may flow to the:
Be seepage
New trap
2 Concepts used
Porosity
Voids / air space that exist between the rock grain
High
open space means
High
porous
Rock that consist
high porosity
: Unconsolidated of
clay
Rock that consist
low porosity
: Unconsolidated of
sand
Example:
Clay
Shale
Permeability
Ability to transmit fluid and gas
Transmission depends on:
Number ad size of interconnection porosity
Total porosity
Example:
High
permeability:
Sand
Low
permeability:
Clay
Emplacement
Cause by water displacement from oil and gas
Water
Consist of mineral and bacteria
Mineral and bacteria will alter the oil composition
The oil become sticky and thick, oil quality become low
Can also cause by oil expose to the surface and sunlight
Oil and Gas Accumulation
Depends on the
porosity
and
permeability
Occur mostly in trap / Reservoir
Example:
Sandstone
Siltstone