Известия Томского политехнического университета: Инжиниринг георесурсов (Nov 2017)
Assessment of geotemperature conditions of bazhenov oil generation (Koltogor mezodepression and its framing structures)
Abstract
The relevance of research is caused by the need to improve the criteria and assessment schemes of hydrocarbon resources by the volume-genetic method based on reconstructions of geothermal regime of oil source Bazhenov formation, as the accumulator of allochthonous Bazhenov oil - the Neocomian oil-gas complex - is a reserve capacity of the resource potential in the southeast of Western Siberia. The aim of the research is to assess the geological time of the deposits entrance into the main oil formation zone based on reconstruction of paleotectonical and geotemperature modes of the Bazhenov formation in the Koltogor mezodepression and its framing structure (south-east Western Siberia) and to identify the conditions of the Bazhenov oil generation. The object of research is oil source Bazhenov formation into deep wells within the Koltogor mezodepression and its framing structure. Research methods: computer paleotectonic and paleotemperature reconstruction of the sedimentary cover in sections of deep wells including the deposits of source rocks; selection of centers of intensive generation of Bazhenov oil by geothermal criteria; construction of paleosections and correlation diagrams on the profile of the studied wells; analysis of distribution of geothermal field parameters and express assessment of the resource density of the generated Bazhenov oil. Research results. The author has collected, systematized and analyzed the results of geological and geophysical exploration and oil-gas potential of the Koltogor mezodepression and its framing structure. The deep heat flow and thermal history of Bazhenov deposits were simulated. The centers of Bazhenov oil generation were identified; the geological time of the deposits entrance into the main oil formation zone was estimated and the conditions of the Bazhenov oil generation were identified. The author obtained the distribution of relative density of resources along the profile of the researched wells. Conclusions. The author determined the spatial and temporal variations of the heat flow density variation from the base of sedimentary cover and geotemperature of Bazhenov formation across the Permian-Triassic Koltogor-Urengoy paleorift. It was ascertained that hydrocarbon generation intensity matches the density of generated resources in depression. Bazhenov oil generation in the section of wells is confirmed by the results of well tests.
