High oil reserves characterize most fields in Western Siberia. However, along with this, zones of the productive formation that are poorly involved in development and production wells, in which products with a high proportion of water are produced, are distinguished within limits. For understanding the causes of this problem, it is important to consider the material composition of the reservoirs. In particular, it is necessary to consider the clay content, which is associated with the reservoir properties of rocks, hydrophilicity, hydrophobicity and, accordingly, with wettability. The article examined and analyzed a representative sample of core study of two wells in the Gubkinsky oil and gas region, which suggested the possible reasons for the lack of oil reserves.

Oil-water-saturated formations of Western Siberian fields represented by polymictic sandstones are often characterized by strong granulometric heterogeneity. This is the reason for an incorrect assessment of the physicochemical properties of reservoirs, including wettability. On the example of the BS9 - BS11 formations of two fields of Surgut oil and gas region, the distribution of wettability of core samples was analyzed. An analysis of the modeling results for the hydrocarbon phase displacement by oil-saturated reservoir water was carried out using the Tulbovich method. To assess reliability of the wettability values, it was proposed to correlate the difference in the masses of water and kerosene displaced during capillary impregnation and centrifugation with differences in the mass of water and kerosene in water-and kerosene-saturated samples. The method was used to plot the distribution of porosity, permeability and relative clay content on the wettability parameter by capillary impregnation and centrifugal displacement. The results obtained were compared with similar dependences of the reservoir properties and clay content on the general wettability parameter. The type of wettability of core samples with good reservoir properties is validated in complex, low-permeability reservoirs with a high content of clay material. It is recommended to use the results of modeling the displacement by capillary impregnation and centrifugation with differences in the mass of water and kerosene.

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The analysis of the relation between the wettability of mineral substance, the porosity and permeability properties of the rock and the nature of the distribution of hydrocarbons was made based on the core samples of the BS-1 and BS-2 productive strata of the Surgut oil and gas field. It was proposed to study the association of hydrophobic, hydrophilic, and mixed groups of collectors to different facies.

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