Structural traps

By:
HAMAS-UL-GHANI
ROLL NO. 11
BS APPLIED GEOLOGY 2ND PROF

Structural Traps
TERMS TO KNOW BEFORE UNDERSTANDING
TRAPS
 Porous rock
 Permeable rock
 Source rock
 Reservoir rock
 Migration path(primary migration and
secondary migration)
 Seal rock/Cap rock/Roof rock

Structural Traps
 Porous rock:
A rock which contains pores in it
 Permeable rock:
A rock which contains interconnected pores
 Source rock:
The rock which generates Hydrocarbons
 Reservoir rock:
Porous and permeable rock unit which holds
Hydrocarbons

Structural Traps
 Seal rock:
An impermeable rock that acts as a barrier to the passage
of further upward migration of Hydrocarbons, migrating
in the subsurface.
 Common seals are:
– Shale
– Evaporites
 Seal overlies the reservoir rock to form a trap.
 Also known as roof rock and cap rock.

Structural Traps
 Primary Migration:
The migration/movement of Hydrocarbons from the
source rock to reservoir rock is called primary migration.
 Secondary Migration:
The movement of Hydrocarbons within the reservoir rock
is called secondary migration.

Structural Traps
What is a Trap?
 Any arrangement of strata that permits the accumulation
of hydrocarbons in commercial quantities is a trap.

Structural Traps
 A trap is the place where oil and gas are barred from
further movement(Levorsen,1967).
 Checks the flow of Hydrocarbons

Structural Traps
 A structural trap is a geological trap that forms as a result
of changes in structure of the subsurface due to tectonic,
gravitational and compactional processes i.e. Folding,
faulting etc.

Types of Structural Traps
 Anticlinal traps
 Fault related traps
 Salt dome traps

Structural Traps
 Anticlinal Trap:
If a permeable rock like sandstone or limestone is
located between impermeable rock layers like shale
and the rocks are folded into an anticline, oil and gas
can move upward in the permeable reservoir rocks,
and accumulate in the upper region of the anticline.

Structural Traps
 Fault-Related Traps:
If faulting can shift permeable and impermeable rocks
so that the permeable rocks always have impermeable
rocks above them, then an oil trap can form.
Both normal and reverse faults can form this type
of oil trap

Structural Traps
 REMEMBER:
A fault plane itself can act as a seal too.

Structural Traps
 Salt Dome Traps:
salt that has moved up through the Earth,
punching through and bending rock along the
way.
Oil can come to rest right up against the
impermeable salt, which makes salt an effective
trap rock

Structural traps

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Structural traps