Multiple Deep Stratigraphic Sources of the Hydrocarbon Fluids in the South-Caspian Basin

Biomarker parameters such as degree of normal sterane isomerization and aromatization of monoaromatic sterane were used for oils maturity determination. Gases maturity had been determined on the base of empirical dependence of the isotopic composition of methane and ethane carbon with vitrinite reflectance. The results showed that oils within the South-Caspian basin are characterized by low degree of maturity (Ro to 0.7%) that increases significantly the prospects of discovery of oils of more mature stages. It had been pointed out that the most mature oils of known fields are generated in Miocene deposits in the central part of the South-Caspian basin. Based from the geological structure of the South-Caspian basin we can assume the correspondence of oil generation peak (Ro=0.8–0.9%) to the Paleogene-Lower Miocene deposits. The oil and gas “windows” are separated by the sedimentary interval with the thickness of 8–10 km.

It had been determined that in the South-Caspian basin the oil-and-gas generation zone is very extended and corresponded to some stratigraphically and hypsometrically isolated sources of fluids generation in the Mesozoic, Paleogene and Miocene deposits. In the South-Caspian basin the sources of oil-and-gas generation are mixed relatively each other and corresponded to various hypsometric and stratigraphic stages.