The Paleozoic Petroleum System of the Berkine and Illizi Basins in Southeast Algeria

By

Allan F. Driggs¹, A. Chaouche¹

 (1) Anadarko Petroleum Corporation, Houston, TX

 The Paleozoic petroleum systems of North Africa contain seven giant fields with greater than 1 billion barrels of oil equivalent. Five are located in the Berkine and Illizi basins. This article describes the productivity and maturity of the petroleum systems and addresses their source rock quality and the oil to source correlation based on the fluid chemistry. Lateral and vertical migration is assessed in the Berkine basin through basin modeling and according to the fluid type. The fluids in the system are well preserved in a mature phase of evolution because of a regional evaporite seal and minimal late tectonic disturbance. The regionally extensive Silurian “Hot Shale”, believed responsible for more than 80% of Paleozoic-sourced hydrocarbons, has been shown geochemically to contribute less than 20 % of oil produced in Berkine basin. The Devonian hot shale (Frasnian) and the “Serie Argileuse” of the Upper Devonian exhibit the strongest oil generative potential. The Illizi Basin to the south of the Berkine Basin produces oil from Silurian source rocks that were not buried deeply. The Illizi Basin has been described by many workers as a platform. The present day maturation level of the Silurian illustrates that long geologic time combined with low reaction rates can mature the source rock.