The Satal Petroleum System of the Western Sirt Basin, Libya - From Reservoir Development to Regional Charge History

Abstract

Summary The Satal Formation of the western Sirt, Libya, is an isolated reef-bounded carbonate platform of Late Maastrichtian-Danian age. The Satal and carbonates units directly above, harbour a prolific petroleum system comprised of several large oil fields sourced from a common generative area. The Satal Platform initially developed on a rifted basement high. As this subsided and base level rose, several highstand aggrading sequences built up and out to form the isolated reef ringed platform, interrupted by occasional exposure/meteoric dissolution events. Early burial was associated with micritization, calcite cementation, neomorphism and dolomitization. Increasing burial during the late Palaeocene and Eocene was marked by solution seams/stylolitization, blocky ferroan calcite and dolomite cements. Porosity is predominantly secondary, dominated by intercrystalline porosity developed during dolomitization and local vuggy dissolution. Towards the end of the Eocene and continuing intermittently into the Plio-Pleistocene, the western part of the Sirt Province was uplifted and partially unroofed tilting the Satal Platform to the east towards the Ajdabiya Trough, reactivating old basement faults and locally fracturing the reservoir. With continued unroofing and tilting, meteoric waters flooded through the western part of the platform with some dissolution locally.