Geology and Petroleum Resources of North-Central and Northeast Africa

James A. Peterson

In north-central and northeast Africa, important petroleum accumulations exist in the Sirte basin of Libya, the western Sahara region of Algeria, the Pelagian platform offshore from eastern Tunisia, and in the Western Desert basin, Suez graben, and Nile delta in Egypt. Approximately 55 major fields (> 100 million BOE), of which 15 are giants (> 1 billion BOE), have been found in these provinces. Total estimated ultimate production from existing fields in 60 billion bbl of oil and 100 tcf of gas; estimated undiscovered petroleum resources are 26 billion bbl of oil and 93 tcf of gas.

The post-Precambrian sedimentary basins of north Africa are related to the development of the Sahara platform during at least four main tectonic episodes (the Caledonian, Hercynian, Laramide, and Alpine cycles). The sedimentary cover of the platform, which includes rocks of all geologic systems, ranges from less than 1,000 m (3,300 ft) in the south to more than 9,000 m (30,000 ft) along the Mediterranean coast. Paleozoic rocks are primarily continental and nearshore marine sandstone and shale, which are important reservoir and source rocks for petroleum in the central and western parts of the Sahara platform. Lower Mesozoic rocks were deposited in a continental and restricted marine environment, and contain thick beds of redbeds and evaporites, including salt, which are important seal for oil and gas fields. Upper Mesozoic and Tertiary rocks are related to the development of the Mediterranean Tethys geosyncline and are characterized by numerous transgressive-regressive cycles of the Tethyan seaway. Marine carbonate and shale facies are dominant in the Upper Jurassic, Cretaceous, and lower Tertiary section of northern Libya, eastern Tunisia-Pelagian platform, and northern Egypt. Upper Tertiary beds are continental clastics on most of the platform, except near the Mediterranean.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.