Is the Extremely Prolific Sirt Basin Onshore Libya Continuing into Deep Water Areas?

Abstract

The onshore part of Sirt Basin is the most prolific petroleum province in whole Africa. It is a large Mesozoic-Cenozoic rift basin. The offshore part has been limited explored without any big success. The main objectives of this presentation are to discuss the possibility that the onshore petroleum systems extends offshore, based on improved understanding of the regional structural and sedimentological settings. 2D seismic interpretation, modelling of gravity and magnetic anomalies, source maturity modelling, structural and sedimentological descriptions have been carried out. Bathymetry and gravity and magnetic anomalies indicate that some areas have been heavily influenced by different volcanic activities (seamounts and sills). The marine Upper Cretaceous Sirt Fm. is expected to be the most probable hydrocarbon source. The thick overburden (2000-7000 meters) in the offshore extension of Ajdabiya Trough indicates that the source, if present, will be gas and/or oil mature in different parts of the area. Lower Cretaceous Nubian sandstones (expected main reservoir) have been penetrated but are heavily calcite and /or quartzite cemented. This study gives a better understanding of the Mesozoic and Cenozoic basin evolution of offshore Sirt Basin. The hydrocarbon potential is good. Reservoir quality is considered as the main risk factor.