ISOTOPIC COMPOSITION OF THE ARYSKUM DEPRESSION OIL (SOUTH KAZAKHSTAN)

• Main Authors: Stanislav I. Golyshev, Nataliya L. Padalko, Rima K. Madisheva, Sultan M. Ozdoev, Vasiliy S. Portnov, Valery I. Isaev
• Format: Article
• Language: Russian
• Published: Tomsk Polytechnic University 2020-03-01
• Series: Известия Томского политехнического университета: Инжиниринг георесурсов
• Subjects: carbon isotope; genesis; oil; aryskum deflection; isotope analysis
• Online Access: http://izvestiya.tpu.ru/archive/article/view/2533/2183

One of the areas discussed in modern geology is the oil and gas potential of deep horizons, including the basement of sedimentary basins. The genesis of oil deposits is the subject of heated debate. Modern geochemical methods for studying a substance, together with the instrument capabilities, which include an isotopic mass-spectrometer, make it possible to distinguish between oils generated by different oil source deposits. The most important indicator identifying the genesis of hydrocarbons with respect to oil and gas formation zones in a specific section is the isotopic composition of carbon. Each zone, in its turn, is characterized by individual geochemical and thermodynamic parameters, including the type and degree of conversion of dispersed organic matter, modern geothermal temperatures and paleotemperature conditions, and the phase composition of hydrocarbons. Deposits of the Aryskum depression of the South Torgai oil and gas basin (South Kazakhstan) are associated with various lithological-stratigraphic complexes of the Jurassic-Cretaceous deposits, the Devonian-Lower Carboniferous formations of the quasi-platform complex and disintegrated basement ledges. In recent years, the prospects of the South Torgai basin have expanded and are associated with pre-Jurassic deposits. In this regard, there is the issue of the nature of hydrocarbon masses and formation of their clusters in the Mesozoic and Pre-Mesozoic formations of the Aryskum depression. The aim of the research is the comparative analysis of the carbon isotopic composition of oils from the Aryskum depression from the Mesozoic, Paleozoic sediments, as well as the ones from the zone of contact of the Paleozoic with the Mesozoic sedimentary cover to solve genetic problems and elucidate the features of the formation of oil fields in the Aryskum depression. The results made it possible to establish the regularity of the change in the d13С value depending on the age, depth, and territorial confinement of the deposits within the Aryskum depression and, based on isotopic data, make an assumption about the genesis of Mesozoic and Pre-Mesozoic oils.