Cretaceous source rocks evaluation inferred from geochemical analysis and basin modeling in Northern-Central Atlas of Tunisia: A guide for exploration

Abstract

We present a petroleum system assessment of the late Albian and late Cenomanian–early Turonian source rocks of the lower Fahdene and Bahloul Fms in Northern Tunisia in the region around Jebel Ech-Cheid and the Bouarada plain. Rock-Eval pyrolysis and basin modeling of drilled wells and seismic-based pseudo-wells were used in the present study. Analyses were performed on samples from outcrops and wells. The results indicate a moderate to good Albian lower Fahdene source rock of mixed type II/III oil and Gas-prone kerogen. The late Cenomanian–early Turonian Bahloul Fm bears a moderate to very good source rock containing oil-prone type II kerogen. Parameters including production index (PI) and T_max indicate that the maturity varies from immature late diagenetic to the Gas generation stage, mainly depending on burial history within the irregular basin architecture. 1D basin modeling of petroleum wells and 2D seismic based pseudo-wells at different structural positions reveals different burial and thermal histories. Regional compression during the Atlas orogeny aborted hydrocarbon maturation at an early stage in uplifted and folded zones. However, transverse grabens experienced continuous burial, leading to advanced hydrocarbon maturity and significant expulsion. These grabens are key exploration targets for finding preserved traps, both within the grabens and at graben edges.