Petrofacial modeling of estuarine type deposits on the example of one of the deposits of the Cherkashinskaya formation of Western Siberia

The article outlines an algorithm for the joint work of a sedimentologist and a petrophysicist to identify of FC that are identified with facies established during the sedimentological study of core material.

Aim. The goal of this work is to conduct petrofacial modeling for estuarine deposits of one of the deposits of Western Siberia in order to demonstrate the basic stages and algorithms for solving this problem.

Materials and methods. Full-size core from 6 wells in the amount of 457 meters as the basic material for sedimentological analysis and 3.450 samples (cylinders), on which standard core studies were carried out, including the determination of the open porosity coefficient Kp and absolute gas permeability K_pr.

Results. Based on the results of the performed sedimentological study of the core and petrophysical studies a petrofacial model of the absolute permeability coefficient has been obtained, which makes it possible to clarify this parameter in the reservoir volume based on a conceptual understanding of the distribution of facies.

Conclusions. As a result of the conducted studies, facies complexes of sediments are described and the characteristics of core facies that belong to the estuary system of mixed (mainly wave) type are given. In the presence of a conceptual geological model, petrofacial modeling allows to reduce the uncertainty of the forecast of the permeability coefficient according to GIS from two to one order of magnitude of the determination of this parameter and to clarify the effective thicknesses in wells without pronounced direct signs of penetration of drilling mud filtrate into the formation, by using fixed values of the classification parameter S for two petrofacies and the corresponding boundary values porosity coefficient for isolation of collectors.

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