Trap and Petroleum Models of Gara Gara South Fields Illizi Basin South East Sahara, Algeria

The Illizi basin is one of the most potential and mature basins in Algeria where many oil and gas were discovered since 1950s. Among these, Gara Gara South Fields located in the center of Illizi basin. Several oil and gas accumulations of various sizes have been found within the F6 reservoir of Silurian-Lower Devonian age and Ordovician in the Illizi basin. Lithologically, the F6 reservoir consists of interbedded sandstones and shales and is subdivided into M, A, B and C units. These reservoirs, which were deposited in offshore coastal bars and tidal channels, show a high degree of lateral and vertical facies variation. The Ordovician reservoir is known by the rapid variation of facies due to the glacial environnement. There are units which produce in some area but does not exist in others. This paper describes the petroleum geology of F6, which contains a gas cap and a rim of oil, and Ordovician reservoirs. In this area, Ordovician does not produce. Also, the purpose of this study is to determine the trap and petroleum models of Gara Gara South Fields, to compare the 2D and 3D interpretations and to explain the wells results.