The Petroleum System from Source
Rock to Trap: Matruh-Shushan Basin, Western Desert, Egypt
By
Farouk I. Metwally1, John D. Pigott2
(1) Helwan University, Cairo, Egypt (2) University of Oklahoma, Norman, OK
After 22 years of exploration, discovery of conventional
play types in the
Matruh-Shushan Basin is nearly complete, and consequently, the search has
commenced for new, less obvious plays. Many of the new opportunities occur
beyond the known hydrocarbon provinces and are considered to have significant
charge risks. To define these risks, extensive basin modeling studies have been
conducted.
Modeling and empirical data show that the Mesozoic
source
generation areas in
the Western Desert are spatially restricted in the Matruh-Shushan basin. These
areas currently are buried at their maximum temperatures. Large parts of north
and central Western Desert depend upon lateral migration from these kitchens for
their charge. Progressive uplift and basin inversion since the
middle
Paleozoic
has provided favorable conditions for lateral migration in the post Paleozoic
interval. The main potential
source
rocks
in the present basin are Lower
Cretaceous Alam El Bueib (AEB) and Jurassic Khatatba. Both
source
rocks
have
mixed kerogen type (II/III) and both attained the highest levels of thermal
maturity at different times. The lower Cretaceous AEB entered the mid-mature oil
windows following the Late Cretaceous, whereas the Khataba reached maturity in
the deeper parts of Matruh-Shushan basin following Turonian times.
Charge risks increase in the deeper Mesozoic
sequences in which migrating
hydrocarbons traversed the basin from the deeper regions. The created dip
gradients and migration pathways by faults augmented updip migration of the
hydrocarbons which were generated from the Jurassic Khatatba and lower
Cretaceous AEB. These hydrocarbons moved into shallower post late Cretaceous
reservoirs
.
Basin modeling has outlined the spatial extent of the different petroleum systems and provides data for risk maps to guide subsequent new exploration phases. The predictions have revitalized some of the mature plays, for example the late Cretaceous Formation, where oil exploration is now focused along late Cretaceous and Tertiary migration pathways. Deeper sections are envisaged to have significant gas potential.