Potential for new hydrocarbon field discovery in Proterozoic deposits of Volga-Urals region

Modest progress in the Vendian-Riphean deposits development in Volga-Urals region are related to the low and nonuniform drilling exploration maturity of these sequences in the area and in the section, scattered and inaccessible geological and geophysical data of various years, absence of the common stratigraphic breakdown and correlation of the Precambrian series (not least because of the lack of parametric matching of the column), insufficient information content of drilling data. All the mentioned factors cause high subsoil user risks and unprofitability of development. The authors present the composite lithologic and stratigraphic section of sedimentary Proterozoic deposits in the Kama Region. They identify the key patterns of oil and gas occurrence in the Upper Proterozoic deposits of the north of the Volga-Urals region. The paper contains the results of petrophysical studies on 1628 samples (taken from 112 wells) for the purpose of studies of Riphean-Vendian reservoir properties. The authors note that fracturing of the Riphean carbonate rocks has a great influence on their porosity and permeability. Resulting from the studies, fractured reservoirs are identified in the Arlansky member of Lower Riphean Kaltasinsky formation, and fractured-cavernous - in the Ashitsky member. Among the Vendian deposits, porous fine-grained sandstone and siltstone of the Kykvinsky and Vereshaginsky formations have good reservoir quality. The authors recommend a number of objects promising for hydrocarbon exploration and make a proposal on future trends of geological exploration efforts