Southern and Western Basins

Measured TOC ranges from 2 to 8% in the Middle Devonian shales, and from 1 to 5% in the Late Devonian shales, but with maximum decreasing concentrations westward from 1.5 to 5.0% in the Illizi Basin, 1.0 to 3.5% in the Mouydir basin, and 1.0 to 1.8% in the Timimoune basin. These variations are likely linked to changes in transport direction and in the provenances of detritus as compared to Silurian shales. The level of organic matter maturation in the Devonian sources in these basins is higher (Ro = 1-4%) than it is in the equivalent sources of the Triassic province (Oued el-Mya, Ghadames, and Trias basins) due to differing sedimentation, burial, and tectonic histories. 

Consequently, gas generation is currently expected to occur in the south and west of the Sahara, with the exception of the Sbaa sub-basin, which is at a lower maturation level. 

Chapter 6 Burial History and Kinetic Modeling for Hydrocarbon Generation 

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