The Geology of the Asl Oilfield, Western Sinai, Egypt

Surface mapping in the Asl area of Sinai, which was carried out in the year 1937, established the presence of 18 gypsum beds alternating with shales, marls and sandy beds, folded into gentle flexured structures with very little faulting. In contrast, the structures at depth, as revealed by the information from 28 wells, consist of numerous tilted blocks bounded by faults; most of these faults die out before reaching the surface. The task of finding locations for producing wells proved difficult; only 12 of the wells drilled have yielded commercial supplies of oil. The value of seismic records is limited in such a geological environment, where deep‐seated, block‐faulted structures are overlain by a thick evaporite succession. Three producing horizons, two of Miocene age and one at the top of the Eocene, have yielded an aggregate of more than six million tons of oil.