Geochemical Evaluation Of Petroleum Potential, Sbaa Region (West Of Algerian Sahara)

The present study focuses on the molecular organic geochemistry, especially biological marker distributions of sources rocks in the Sbaa basin (west of the Algerian Sahara) as well as a tentative of an oil-source rock correlation is also carried out in the study area. The study area is situated in the southwest of the Timimoun basin (west of the Algerian Sahara). It is bounded to the west by the Ougarta mountains and to the east by the Azzene arch. This area contains several hydrocarbon accumulations, located in the Tournaisian, Strunian and Namurian reservoirs. This paper reports a study of an oil-source correlation involving core samples from Devonian (Givetian and Frasnian) and Silurian source rocks and oils from this basin. From the bulk data of source rocks, there are some good Givetian to excellent Frasnian and Silurian source rocks. Based on biological marker distributions, these source rocks appear to be of marine input constituted by a combination of algal and amorphous material. Thus, these data reveal one group of oils, similar to each other, which were probably derived from source rock(s) of marine input and depositional environment. Based on maturity parameters, all these oils are mature and were probably originated by mature Silurian source rock. The geochemical modelling shows that thermal maturity is relatively lower for source rocks located at the southwest during the Palaeozoic time. Therefore, generation of hydrocarbons continues during the Mesozoic time reaching the Cenozoic time. Expulsion of hydrocarbons generated by these source rocks in the Sbaa basin, started from Devonian and continues during the Mesozoic time. Migration of hydrocarbons was oriented first vertically towards adjacent reservoirs to source rocks then laterally towards southwest of the study area. The whole variations recovered on the nature and maturity of the source rocks as well as hydrocarbon generation and expulsion, are the results of thermal and geodynamic activities happened in this region