MATURITY AND SOURCE-ROCK POTENTIAL OF MESOZOIC AND PALAEOZOIC SEDIMENTS, JIFARAH BASIN, NW LIBYA

A.  Abohajar¹, B.M. Krooss², M. Harouda³ and R. Littke^2*

¹ Fugro Geoscience GmbH – Libya, Dat El-Imad Complex, Tower 5, First Floor, PO Box  91730, Tripoli, Libya.

² Institute of Geology and Geochemistry of Petroleum and Coal, RWTH Aachen University, Lochnerstr. 4-20, 52056 Aachen, Germany

³ National Oil Corporation (NOC), PO Box 2655, Tripoli, Libya.

* Corresponding author: littke@lek.rwth-aachen.de

The Jifarah Basin, NW Libya, has a sedimentary fill which includes marine shales of Triassic, Permian, Silurian and Ordovician ages together with Jurassic evaporites and Cambro-Ordovician aeolian sandstones. Major risk in exploration of the basin is associated with the presence of source rocks. The present study investigates potential source rocks in the basin and assesses their thermal maturity, petroleum generation potential, organic richness and distribution. Cuttings and core samples from nine wells were analyzed using a Rock-Eval 6 instrument and by standard petrographic microscopy. Kerogen type and amount were recorded.

Triassic and Ordovician formations were only drilled in parts of the basin and have minor petroleum generation potential. Permian and Devonian samples also had low generation potential, as did samples from the upper part of the Silurian. The Devonian succession is of limited extent as a result of Hercynian uplift and erosion.

Major petroleum generation potential is associated with the lower part of the Silurian Tanezzuft Formation in which high TOC values and moderate to high HI values were recorded. The formation is characterized by abundant fluorescing alginite. Most samples studied were early mature to mid-mature but there was some regional variability.

Key words: Jifarah Basin, Libya, kerogen type, thermal maturity, petroleum potential, Tanezzuft Formation, Rock-Eval pyrolysis.

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