AN EVALUATION OF THE HYDROCARBON POTENTIAL OF THE SEDIMENTARY BASINS OF LIBYA

Abstract

Distinctive structural and stratigraphic styles, together with the timely development of source rocks, reservoirs and seals, have produced in Libya the richest hydrocarbon habitats on the African continent. These habitats are located in the Sirte Basin (29,000 MM brl of proved reserves), and Ghadames Basins and Pelagian Shelf (3,000 MM brls of proved reserves). Significant oil discoveries have also been made in the Murzuk Basin (1,500 MM brl of proved reserves) and the offshore Cyrenaica Platform.Four major potential source rocks have been identified in Libya: the Sirte shales (Campanian), the Hagfa shales (Palaeocene), the Tanezzuft shales (Silurian), and shales of Devonian age. The Sirte and Hagfa shales have generated hydrocarbons for most of the prolific reservoirs in the Sirte Basin. The Sirte shales supply hydrocarbons to clastic reservoirs of Cambro‐Ordovician age (the Gargaf Group) and Lower Cretaceous age (Nubian sandstones), and also to Upper Cretaceous carbonates. The Hagfa shales source most of the Tertiary reservoirs in the Sirte Basin and possibly the Cyrenaica Platform. Silurian (Tanezzuft) and Devonian shales supply hydrocarbons to reservoirs of Palaeozoic and Mesozoic ages, particularly Silurian and Devonian sandstones in the Ghadames and Murzuk Basins, and the Cyrenaica Platform.The principal seals in the Sirte Basin are Late Cretaceous and Tertiary shales and anhydrites. Palaeozoic and Mesozoic shales, impermeable carbonates, and occasional anhydrites form the major seals in the Ghadames and Murzuk Basins and the Cyrenaica Platform.