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.