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Geohistory Analysis, Mapping of Source Beds, Timing of Hydrocarbon Generated, and Undiscovered Reserves in East Abu Gharadig Basin, Western Desert, Egypt


 Ahmed Nabil Shahin1, Mosaad M. El-Lebbudy2

(1) Alamein Petroleum Company, Cairo, Egypt (2) Gulf of Suez Petroleum Company, Cairo, Egypt

 The sedimentary sequence the eastern Abu Gharadig basin, west of Lake Qarun includes several potential source units; Abu Roash "F" Member and intervals within Khoman Formation; Abu Roash "G" Member, Bahariya Formation and the Safa Member of the Jurassic Khatatba Formation. Maturation models of several drilled sections, supported by models of interpolated basinal sections, suggest that migration would have been initiated in the depocenters from potential Jurassic source beds during early Senonian and thus trapped in pre-Laramide structures. As the basin center subsided throughout the latest Cretaceous and Tertiary, potential Jurassic sources passed through the "oil window" and could have expelled oil. The mature area of the Jurassic expanded away from the depocenters, concomitant with the subsidence process. The least preservation risk is considered for hydrocarbons expelled from Jurassic rocks bounding the basin away from the depocenter, as these rocks were late in reaching peak generation, past the Oligo-Miocene. However, preservation of re-migrated hydrocarbons is also valid. For the Cretaceous source beds, timing of the structural growth indicates that Laramide-related potential prospects were existing during the Late Eocene, the time of hydrocarbon migration from the Abu Roash "F" source rocks. Hydrocarbons expelled by Cretaceous source rocks are considered well preserved. Estimated recoverable total reserves in the area are about 670 million oil-equivalent barrels, based on geochemical mass balance.