The Stratigraphy of the Libyan Sedimentary Basins and Their Current and Potential Entrapment of Hydrocarbons

Hassan S. Hassan and Christopher G. Kendall
Geological Sciences, University South Carolina, Columbia, SC

Libya's five major onshore basins are: the interior fracture basin of Sirt; the three interior sags of Murzuq, Kufra, Ghadamis; the onshore stable Cyrenaica platform cratonic margin; the onshore/offshore foreland basins of Benghazi and Derna. Offshore are the trailing margin basins of Tripolitania and the Gulf of Sidra (Sirt Embayment). The Sirt, Ghadamis, Murzuq and Sabratah have 320 producing fields with reserves exceeding 50 billion barrels oil and 40 trillion cubic feet gas.

Sirt Basin, the most prolific oil basin of North Africa, has 89% of Libya's reserves hosting sixteen giant oil fields with 117 billion barrels oil. The Cretaceous and Paleocene rocks form reservoir sequences and the Upper Cretaceous Sirt Shale a major source rock. Grabens sequester organic rich shale and local up dip quartz sand bodies, while horsts host carbonate build-ups.

Ghadamis intracratonic basin has 5200 m of clastic Paleozoic through Mesozoic strata with 3.5 billion bbl of oil production from the Upper Silurian Akakus Formation and the Tadrart-Ouan Kasa Formations.

Central Muruzq Basin has 3000 m section of Cambrian to Quaternary with oil reserves of 1 billion barrels. Potential reservoirs include the Memouniat, Acacus and Tadrart-Kasa sandstones with the major source rock of the Silurian Tanezzuft Shale.

Major offshore oil production in the Tripolitania Basin is from El-Bouri oilfield from Eocene Nummulitic Limestone with 60,000 bbl/d, and 2 billion barrels reserves.

Mesozoic-Tertiary rocks of Cyrenaica and Paleozoic of Al Kufra Basin have no commercial production but the Cretaceous to early Tertiary have potential. Devonian sandstones and Tertiary carbonates contain gas shows in Cyrenaica.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas