Omar Imbarek

The Cyrenaica Basin is located in the northeast part of Libya, along the North African coast. It comprises two distinct tectonic provinces sandwiched by the Cyrenaican Fault System. The area has been influenced by Tethyan tectonics since its opening during the Jurassic. The highest geomorphologic feature in the Cyrenaica region is the Al-Jabal Al-Akhdar uplift; located on the northern edge of the Cyrenaica Basin and comprising sedimentary rocks, from Upper Cretaceous to Tertiary in age.

The Eocene carbonate successions of the Ras Al-Hilal and Farwah groups in the Cyrenaica and Tarabulus basins were deposited on a wide, gently dipping, north-northeast carbonate ramp that comprises a wide variety of facies including larger benthonic foraminferal fossils. Structurally this carbonate ramp is east-west trending, elongate, with high relief, formed as a result of Late Cretaceous or Late Tertiary tectonic events. These tectonic events controlled the facies distribution in the study area. Several diagentic processes including cementation, dissolution, micritization, dolomitization, fracturing, and stylolitization have affected these facies.

The key objectives of this project are: (1) to evaluate the tectonic pattern during the deposition of the Eocene sediments in northern Libya; (2) to determine the effect of diagenesis on lithotypes; (3) to predict reservoir heterogeneity and quality on a complex carbonate ramp-system; and (4) to study and evaluate the Eocene carbonate ramp systems of northeast onshore and northwest offshore Libya. The Ras Al-Hilal carbonate succession is an ideal subsurface analog in part because of extensive outcrops and lateral continuity. It was studied to understand depositional geometry, facies distribution, and reservoir characterization of subsurface reservoirs of the Farwah Group.

The outcrops of the Ras Al-Hilal Group in the Cyhrenaica Basin comprise mainly muddy facies of the Apollonia Formation and nummulitid facies of the Dernah Formation. In contrast, the Farwah Group in the subsurface is composed mainly of dolomitic-limestone facies of the Jirani Formation and nummulitids and other associated facies of the Jdeir Formation, which form the principal hydrocarbon reservoir facies in the northwest Libyan offshore petroleum system. Thus, this study of the Ras Al-Hilal carbonate successions at outcrop scale can provide analog information that will contribute to the understanding of subsurface oil and gas reservoirs.

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Supervisor: Grant Wach