The decrease in oil reserves production in traditional terrigenous reservoirs on the territory of the Russian Federation makes more and more attention to the exploration and development of oil and gas deposits in carbonate deposits. One of such promising areas is the Yurubcheno-Tokhomsky oil and gas accumulation zone. It is a carbonate reservoir.
The article presents the results of studying the heterogeneous structure of the carbonate reservoir of the Riphean age of the Yurubcheno-Tokhomsky zone using petrophysical methods, core studies, including special methods for studying the different types of pore volume genesis (optical – microscopy, stereomicroscopy, tomography and microtomography and others). As a result of a combination of lithological and petrophysical studies, patterns of the distribution of slit-like voids in intraclast dolomites, as the main type of reservoir of a productive Riphean reservoir, are determined. Quantitative characteristics of various types of volume are given. Criteria for contouring and quantitative assessment of the the poro-perm properties of prospective intervals in the section of wells have been developed, and a conceptual geological model of the Riphean reservoir has been determined. Based on the systematization of geological, geophysical, and field information, criteria for the productivity of Riphean deposits, such as the presence of intraclast dolomites, silicification, increased fracturing, and clayiness, are determined. The identified criteria made it possible to establish the patterns of distribution of promising zones within the Yurubcheno-Tokhomsky reservoir, which made it possible to make field development more efficient. Thanks to the definition of the conceptual model, the trajectories of horizontal wells are currently being adjusted, which allows to receive initial oil rates of wells higher than planned.
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