Generation potential of organic matter of the Upper Jurassic deposits within the Karabash search zone

Abstract

The article considers the geochemical characteristics of the rocks of the Bazhenov and Nizhnetutleim formations in the southwestern part of the West Siberian oil and gas province, or rather in the territory of the Karabash search zone. The work was carried out on the basis of the core material study of the section of 29 wells within the Karabash zone by pyrolysis on the Rock-Eval 6. The regularities of the distribution of organic carbon concentrations (Сorg, %) on the studied territory were obtained. With the help of data mapping, it was established that the maximum concentrations of organic matter are timed to the southern regions of the zone (the most submerged parts of the paleobasin). The assessment of the catagenesis degree (degree of maturity) of organic matter of the Bazhenov horizon in the study area was carried out. Level maturity of organic matter of rocks is specified in the parameter Tmax Rock-Eval. Within the study area it’s increasing from South to North, from graduation PK3 (according to the scale of N.B. Vassoevich) (Tmax < 430 0С) in the area of wells Verkhnetyumskaya 34 to MK2 (Tmax 440–445 0С) in the area of Molodezhnaya and the Zapadno-Frolovskaya square. The resulting catagenetic zoning determined the boundaries of the generation kitchen for this territory. Generation scale for the Upper Jurassic source rocks was estimated, taking into account its lithofacial structure.