Abstract: Source Rock Identification and Hydrocarbon Generation Related to Trap Formation of Allal High, Algerian Sahara

A. Rahmani, N. Yahi, M. Issad

The Allal structure is located on the Saharan platform in central Algeria. The structure covers approximately 50,000 sq km between Oued Mya basin in the East and Gourara in the West. Although exploration started in the late 1950s, only a few wells were drilled in this region. Gas was discovered. The sedimentary fill, mainly Paleozoic shales and sandstones, being covered by Mesozoic evaporites overlying hercynian unconformity surface, has a thickness ranging from 2000 to 7000 meters. The potential reservoirs are Siegenian-Gedinnian, Famennian and Tournaisian sandstones deposited in transitional and marginal marine environments. The Silurian, Midlle Devonian and Famennian shales are established as source rocks. Kerogen is type II for both the Silurian and Midlle Devonian, and type II-II for Famennian. Maturation analyses and kinetic modeling evolution of the extracted organic matter indicate favourable gas generation timing related to trap formation ages. In view of the depositional environments, mixed and lithologic type traps can be expected.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994