Sirte Basin

Along the southwest and west margins of the province are extrusive igneous deposits that tend to diminish the hydrocarbon potential of these areas.

[5] According to the designation scheme of Bally and Snelson, it is classified as 1211; a cratonic basin located on earlier rifted grabens on a rigid lithosphere and not associated with formation of megasutures.

[7] The area's structural weakness is exemplified by alternating periods of uplift and subsidence originating in the Late Precambrian, commencing with the Pan-African orogeny that consolidated a number of proto-continental fragments into an early Gondwanaland.

The Late Cretaceous rifting event is characterized by formation of a sequence of northwest-trending horsts and grabens that step progressively downward to the east; the Sirte Trough represents the deepest portion of the basin.

These horsts and grabens extend from onshore areas northward into a complex offshore terrane that includes the Ionian Sea abyssal plain to the northeast.

Oil and gas trapped within the porous rock unit migrate to a high point in the structure because of their low density.

[9] The first reported petroleum occurrence in the Sirte Basin was observed in a coastal water well drilled by Italian colonists during the Italian-occupation.

Competitive bidding for concessions was subsequently permitted by two mineral laws passed in 1953 and 1955, and exploration by Esso, Mobil, Texas Gulf, and others commenced with seismic, magnetic, and gravity data being collected.

Since then, American and other foreign oil companies have returned to resume their operations in Libya, led by AGIP (Italy), OMV(Austria), Veba (Germany), Total (France), Nimir (Saudi Arabia), WOC (National Oil Corporation, Conoco, Marathon, Amerada Hess), and ETAP of Tunisia.

[14] Libya's onshore oil has historically been discovered mainly within the confines of three major geological trends occurring in the Sirte Basin: Notes: 1.

[17] The Messla Field produces from the Lower Cretaceous fluvial Sarir sandstone 27 m thick at a depth of 2682 m.[18] The Intisar 'D' Oil Field produces from an upper Paleocene pinnacle reef 385 m thick, 5 km in diameter, and at a depth of about 2700 m[19] Due to the debts of companies in the sector, oil production dropped by 300,000 barrels per day in Libya, falling to less than 1 million b/d in April 2021 from 1.3 million the month before.