Mesozoic and Cenozoic petroleum systems of North Africa

Abstract

Abstract The Mesozoic and Tertiary petroleum systems of North Africa have formed in a suite of extensional basins developed along the Atlantic and Tethyan margin. Petroleum is unevenly spread across the region of Mesozoic basin development, with one world-class petroleum province developed (the Sirt Basin of Libya), and several more modest developments of reserves in Western Egypt and offshore Libya-Tunisia. A set of these extensional basins were later subject to compression on the Atlas and Syrian trends, with generally unfavourable effects for the preservation of the petroleum systems affected. The Moroccan passive margin is also a region of currently low exploration success. Productive reservoirs are spread throughout the Mesozoic section, though, with the exception of the prolific Early Cretaceous clastic deposits and the Paleogene carbonates, are generally not seen to correlate between basins. Effective source rock development is heavily concentrated in the Late Cretaceous and Eocene. Recent evidence also suggests an additional contribution from lacustrine source rocks of Early Cretaceous and older age in the southeastern Sirt Basin. Patterns of maturity on these main source levels, and timing of that maturity relative to trap formation, seem to be the main controls on basin success and failure, with preservation an additional key factor in inverted basins. The Mesozoic basins of North Africa are generally lightly explored compared with basins of similar petroleum productivity elsewhere in the world. Exploration to date in the Sirt Basin, for instance, has barely progressed beyond the structural trap stage, with application of analogues suggesting undrilled potential in various types of subtle trap. Further exploration remains necessary in the Atlas trend and Moroccan margin, focused on plays with more favourable timing relationships between generation and structural development than those drilled to date.