Published April 2012

Maturity of hydrocarbon fluids and depth-stratigraphic hotbeds of fluid generation sources in south caspian basin

D. A. Huseynov

The article deals with maturity issues of oils and gases coming out from fields and mud volcanoes in South Caspian basin (SCB). Highly informative and widely applied biomarker studies have been used as isomeration degree of sterane for oils and as aromatization of monoaromatic sterane. Maturity of gases was defined according to the empirical dependence between isotope compositions of carbon in methane and ethane with reflection capacity of vitrinite. Results of study showed that oils of SCB are characterized not-too-high maturity and this significantly increases the perspectives of finding oils attributed to higher maturity stages. It was indicated that the most mature oils in known fields were appeared in diatom strata group in central section of SCB. Taking into account the geological structure of SCB, peak in oil generation conforms to Paleogene Lower Miocene settlings. It was defined that oil-gas generation zone in SCB is significantly spread in longitudinal direction and conforms to several fluid generation sources located in separate stratigraphically and hypsometrically on Mesozoic, Paleogene Lower Miocene and diatom settlings. Oil-gas generation sources in SCB are located in distance in relation to each-other and conform to stratigraphic levels. It was indicated that oil-gas generation sources are only located locally in settling cover.