Improving the forecasting methodology of the nature of the inflow in heterogeneously saturated reservoirs of the Achimov formation based on well logging data

The article considers the problem of predicting the nature of the inflow of Achimov reservoirs in the northern part of Western Siberia. The solution of the problem is complicated by a number of factors: geological heterogeneity, low porosity and permeability, variability and low mineralization of formation waters, the presence of abnormally high formation pressure and high formation temperatures. The paper considers the results of special laboratory experiments on electrical, capillary, filtration characteristics of rocks and their comparison with the results of geophysical well logging. The nature of changes in porosity and saturation parameters depending on the mineralization of formation water under atmospheric and reservoir conditions was established. Correlations between critical water saturation values and the water and oil content in the reservoir were established in order to determine the nature of rock saturation, taking into account the intervals of the sub-reservoir by combining capillary, electrical and filtration models. Based on the obtained results, a method for determining the water saturation coefficient of rocks using the Dakhnov-Archie model and a method for verifying formation water mineralization over a field area under conditions of its variability were improved. A method for determining the saturation nature of reservoirs, taking into account sub-reservoir intervals, was also refined. Validation of the proposed method demonstrated a significant increase in the reliability of initial water cut prediction based on well logging data.

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