The Osinsky reservoir as a model of a geofluidodynamic system: hydrocarbon generation centres, migration routes and accumulation sites

The objective of the study is to present the analysis results of the distribution patterns of hydrocarbon accumulations for the case of the Osinsky productive horizon as a regional hydrocarbon reservoir and an independent geofluidodynamic system. The work uses the drilling and geophysical operation data, as well as research materials published in the open press. The Osinsky oil and gas horizon occurring in the lower parts of the Cambrian section is a widespread productive horizon in the area of oil and gas-bearing regions in the south of a number of tectonic structures of the Siberian platform (Angara-Lena bench, Baikit anteclise, southwestern part of the Nepa-Botuoba anteclise, Angara fold zone). The obtained oil exploration results showed that the Osinsky horizon is the only stratigraphic level of the Vendian-Lower Cambrian carbonate complex characterized by regional oil and gas potential. The formation conditions of the fluid dynamic system of the Osinsky mega-reservoir are determined by the nature of the lithological-facies formation environment, which determined its geological heterogeneity, features of its lithological composition, wide areal distribution in the structures of oil and gas bearing regions, possible migration routes of hydrocarbons from generation centres. Each geofluidodynamic system consists of oil and gas generation centres, migration route channels, natural containers of hydrocarbons – reservoirs and traps, reservoir rocks and seal rocks, and is also controlled by a favourable combination of these factors in geological time and space. The ordinary fluid dynamic system is represented by hydrocarbon solutions in the oil and gas generation centres, which are the defluidization places of oil and gas source rocks of the sedimentary oil and gas basin. The Osinsky horizon in the central regions of the Lena-Tunguska oil and gas province is associated with the deposits of various phase composition of hydrocarbons of the Markovskoye, Danilovskoye, Pilyudinskoye, Yaraktinskoye, Chayandinskoye, Srednebotuobinskoye, Talakanskoye, Kovyktinskoye and other fields, where its industrial productivity has been proven. The Sredne-Usolsky Osinsky reservoir is regionally oil and gas bearing in the oil and gas bearing areas of the Baikitskaya and Nepa-Botuoba anteclise as well as the Angara-Lena bench and the zone of the Angara folds. Today, the Osinsky horizon is associated with further growing prospects of hydrocarbon resources in the Vendian-Lower Cambrian carbonate complex.