Effect of Basin Geometry on Locating Promising Hydrocarbon Traps: Tiba Natrun - Kattaniya Inverted Basin, Northern Western Desert (Egypt)
By
Adel R. Moustafa1, Mohamed Abd El-Aziz2, Waleed Gaber3
(1) Department of Geology, Ain Shams University, Cairo 11566, Egypt (2) Qarun Petroleum Company, Cairo, Egypt (3) Shell Egypt, Cairo, Egypt
The Tiba Natrun - Kattaniya basin is a Jurassic-Early Cretaceous rift basin
bounded on the north by ENE-oriented faults linked by NE- and WNW-oriented
transfer faults. Late Cretaceous-Early Tertiary inversion of the basin due to
WNW-ESE shortening involved a component of right-lateral slip on the
ENE-oriented faults. The ENE- and NE-oriented faults at the rift boundary were
predominantly reactivated by reverse slip leading to enormous uplift of the
hydrocarbon source rocks from the depocenter of the basin. In contrast,
continuous subsidence of the WNW-oriented rift segments (e.g. at Tiba Natrun
sub-basin) allowed hydrocarbon maturation
and expulsion from potential source
rocks.
Intra-basin structures formed by inversion include NE-oriented folds and
reverse faults forming excellent hydrocarbon traps (e.g. El-Ahram, Qarun, N.
Qarun, SW Qarun, and N. Harun oil fields). Thick, syn-inversion Eocene rocks
were deposited in a foredeep basin lying south of the highly inverted area
allowing maturation
of Cretaceous source rocks. Extensive exploration in the
area indicates that hydrocarbon traps in the highly inverted part of the basin
are not suitable sites for hydrocarbon accumulation due to halting hydrocarbon
maturation
(as a result of inversion) and lack of trap integrity (breaching by
erosion, absence of top seal, high fracturing, etc.). Intra-basin hydrocarbon
traps are the best prospects within the inverted basin. Continuously subsiding
parts of the basin at the WNW-oriented rift segments are also promising areas
for hydrocarbon
maturation
and expulsion into updip structural traps.