The source rocks of the oil-bearing series of the Eastern Sahara are very old (up to 440 million years) and have been subjected for long periods to considerable burial. For this reason, the oils exhibit a very advanced character of maturation and their overall composition, as well as that of the saturated hydrocarbons, is fairly uniform. An analysis of the aromatic hydrocarbons, especially of the compounds of the steroid type containing one or several aromatized rings, by mass spectrometry makes it possible to distinguish three groups of oil and to find their source rocks.

A mathematical model of the formation of petroleum and gas which uses the reconstruction of the structural history of the basin and the geothermal data makes it possible to calculate the quantities of hydrocarbons formed in the various sectors of the basin. The results are in agreement with the distribution of the presently known deposits, and these allow us to delimit the regions in which oil deposits may exist.