Bitumen Formation in the Source Rocks of the Infrasaliferous Series of the Eastern Part of the Precaspian Basin

Approximately 145 samples from the Eastern part of Precaspian and Preouralian basins were analyzed. They are clastic and carbonated rocks (mudstone, siltstone, sandstone, limestone and anhydrite) of platform, slope and basin facies of Devonian, Carboniferous and Permian whose the depth lies between 1700m and 5450m. The samples were analyzed by petrographic (macerals and vitrinite reflectance), geochemical (extract and Rock-Eval) and molecular studies. These studies show that one could distinguish three groups of organic matter (OM): II (marine), III (continental) and mixed II/III. The type III MO presents the IH generally lower than 80 mg/g TOC and is widespread in the turbiditic facies of Lower Permian age and Lower-Middle Visean. This type presents the humic facies composed of coal remains (vitrinite and inertinite) sometimes associated with a sapropelic matrix or spores.