Unconformity Traps Potential of Sirte Basin, Libya

Muhammad W. Ibrahim
Target Exploration, London, United Kingdom

Stratigraphic studies of the Phanerozoic rocks of Libya re-traced 19 regional unconformities; which are amalgamated into 4 major unconformities in Eastern Sirte Basin (Wenneker et al 1996). Sub-unconformity stratigraphic trapping situations induced by the deposition of post-unconformity seal facies over pre-unconformity reservoir facies in the Pre-Cenozoic sequences of Eastern Sirte Basin were studied and mapped in an attempt to identify proven sub-unconformity plays and outline the potential for similar or additional unconformable stratigraphic trapping plays in the Pre-Upper Cretaceous Sirte group sandstone reservoirs.

The study delineated several areas of interests, leads, and anomalies which were grouped into 10 play fairways of sub-unconformity stratigraphic trapping potential in the proven Bahi-Maragh, Nubian, Amal, Hofra-Gargaf sandstones reservoirs of the Sirte Group. The plays are over-sealed and charged by Upper Cretaceous Rakb and Kalash carbonate-shale facies, below the regional Pre-Upper Cretaceous unconformity, and under-sealed by igneous and metamorphic basement rocks, across the Caledonian Unconformity.

As remaining conventional structural traps are becoming smaller and largely marginal, the deliberate exploration for stratigraphic, combination and hydrodynamic traps is long overdue, and the delineated fairways in this paper may engulf some of the remaining undiscovered large subtle fields of Libya.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005