Geochemical analysis of oil and core samples derived from oil and gas fields in the South-Mangyshlak basin

This paper presents the results of biomarker analysis of 183 oil samples derived from 19 oil and gas fields and Rock-Eval pyrolysis performed on 93 core samples from 12 fields in the South Mangyshlak basin. According to the biomarkers, oils of studied fields were formed from shaly OM and can be divided into 3 groups: the first group includes Oymasha, Ashiagar, Atambay-Sartobe, Alatyube, Karagie North and Akkar North, which have OM of marine origin, while the second group includes oils from the Pridorozhnoye, Airantakyr, Burmasha and Bekturly fields, which have OM of lacustrine origin. The third group includes oils from rest fields, within each of which there are at least two sources: the oils of the lower pay zones have shaly OM of marine origin, and the OM of the oils of the upper horizons was formed in the lacustrine environment. Rock-Eval pyrolysis revealed that some fields can be considered synclinal. Keywords: chromatography; biomarkers; steranes; hopanes; Rock-Eval pyrolysis; South-Mangyshlak.