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Mass Balance Assessment of Petroleum Systems Recognized in the Northern Western Desert of Egypt

Shahin, Ahmed N.1
1 Dover Investments, Cairo, Egypt.

The northern part of the Western Desert (WD) of Egypt, bound from the east by the River Nile, occupies a vast area of intra-cratonic basins covered by prospective Paleozoic to Tertiary sediments. Structural, stratigraphic and maturation studies indicate that migration, guided by buoyancy drive, was initiated in the depocenters from potential Devonian and Jurassic source beds during Early Senonian and trapped in pre-Laramide structures. Pods of active sources were defined based on maturity modeling and mapping isopachs and pyrolysis results of data from 640 wells. Hydrocarbon charges, losses from catchment areas and recovery factors were normalized statistically. The least preservation risk is considered for hydrocarbons migrated from Cretaceous sources after the Alpine tectonics. Accordingly,the WD can be subdivided into five petroleum systems.

The Safa-Bahariya (!), SB (!) system includes Abu Gharadig basin. The system hosts twelve fields and is multi-sourced by Jurassic and Cretaceous intervals. The system is suggested to host 11 billion oil-equivalent barrels (Boeb) as estimated ultimate recoverable reserves (EURR).

The Safa-Alamein (!), SA (!) system, to the north from SB (!), includes Alamein basin, which feeds five fields. The system has the highest discovery density and the highest success rate. The Aptian Alamein Dolomite, the main reservoir, is sourced by the Jurassic Safa mbr. The EURR are seven Boeb.

The Safa-Khatatba (!), SK (!) system is the largest and extends northward into the Mediterranean. Matruh and Shushan basins are the host for the Safa mbr effective source and reservoir. The newly discovered Cretaceous zones in old fields (e.g. Umbarka Field)indicate preserved, old but undisturbed, accumulations. This system is estimated to host 25 Boeb of EURR.

The Zeitun-Safa (.), ZS (.) system, extends into the Libyan territory to the west. A recent (2008) 3,000 bpd discovery West Kalabsha area, proved a Jurassic Safa mbr oil play. This system is estimated to contain URR in excess of two Boeb of Jurassic oil and gas sourced by Paleozoic.

The Khatatba-Kharita (.), KK (.) system is crossed by the Nile Valley, to the south from Cairo and includes the East Beni Suef Field, with 0.3 Boeb preliminary in-place reserves in Albian Kharita sands, sourced by Khatatba Fm, and estimated to host three Boeb EURR.

Cumulatively, the five systems are under explored, being estimated to host 48 Boeb EURR, about 15 times the proven ultimate recoverable reserves.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009