PALEOFACIES — BASIS OF RESERVOIR DEVELOPMENT DESIGN

Abstract

Apt-Alb-Cenomanian age rocks (K1a-al + K2s) within the northern part of the West Siberian oil and gas province (OGP) are the main commercial gas production target in the Russian Federation. However, at present there are certain prerequisites and significant reserves to increase the raw hydrocarbon base and gas production in the central regions of Western Siberia. For further study of the geological structure of these sediments in order to assess their oil and gas potential, it is necessary to set up and carry out complex geological, geophysical and special studies (including sedimentological identification of sediments, detailed reconstruction of paleogeographic sedimentation settings, paleofacial analysis of rocks, petrophysical support of the works). This will make it possible to increase the accuracy and reliability of the planned works on oil and gas prospecting and exploration, as well as to carry out a qualitative forecast of the area development of promising complex reservoir rocks, to perform a full calculation of the initial geological reserves of hydrocarbons for a number of new objects (including PK5, PK7, PK8) and to build highquality geological and hydrodynamic models of hydrocarbon deposits necessary for the design of their further development.A detailed analysis of the primary geological and geophysical materials at our disposal has shown that during the formation of the Pokur Formation in the Middle Ob oil and gas bearing area (OGO) there were heterogeneous conditions of sedimentation — from purely continental to coastal-marine. High lithologic and facies heterogeneity of the studied sediments is observed everywhere. These circumstances complicate the processes of detailed correlation in these sediments, and in some cases — unrealized in practice even within one exploration area. Stratification of productive strata is the most important part of oil and gas prospecting and exploration. According to the results of our studies, the upper strata are most well traced (in some cases up to the hypsometric level of PK3-4 strata occurrence). Their confident area correlation makes it possible to identify smaller stratigraphic subdivisions (packs) in these strata and to determine the paleofacial genesis of these sediments.