Formation conditions and evolution of the oil and gas strata of the prospective East Siberian oil and gas province

Abstract

Introduction. East Siberian Sea shelf refers to the Novosibirsk-Chukotka prospective oil and gas province. The definition of the East Siberian shelf as a prospective oil and gas province and its division into areas is based, along with the structural and geological prerequisites, on the identification of numerous bitumen occurrences in the Paleozoic, Triassic and Jurassic sediments of the Novosibirsk Islands.Aim. To construct spatio-temporal digital models of sedimentary basins and hydrocarbon systems for the main horizons of source rocks, as well as to carry out their detailed analysis based on the available information about the oil and gas content, the gas-chemical composition of sediments, the characteristics of the component composition and evolution of source rocks within the studied prospective oil and gas province. The conducted research made it possible to study regional trends in oil and gas content, features of the sedimentary cover formation and the development of hydrocarbon systems in the area under study.Materials and methods. The materials of production reports obtained for individual large objects in the water area were the source of information. A basin analysis was based on a model developed by the Equinor specialists (Somme et al., 2018) [8, 9], which covered the time period from the Triassic to Paleogene inclusive and took into account the plate-tectonic reconstructions performed by Dor’e et al. in 2015. The resulting model included four main sedimentary complexes: pre-Aptian, Apt-Upper Cretaceous, Paleogene, and Neogene-Quaternary.Results. The calculation of numerical models was carried out in two versions with different types of kerogen of oil and gas source strata corresponding to humic and sapropel organic matter. The key factor in controlling the development of hydrocarbon systems was found to be the sinking rate of the basins and the thickness of the formed overburden complexes.Conclusion. The conducted analysis allowed the most promising research objects to be identified. The main foci of hydrocarbon generation in the Aptian-Late Cretaceous and Paleogene complexes were identified, along with the area of their most probable accumulation. Significant hydrocarbon potential is expected in the Paleogene clinoforms of the Eastern Arctic. This complex is currently underestimated, thus requiring further resource assessment study. A detailed mapping of its interior structure should be carried out.