Updating a reservoir geological model in order to optimize waterflooding when extracting residual oil reserves from stagnant zones

Abstract

Background. In the Russian Federation, as well as in many other oil and gas producing countries, waterflooding technology is frequently used as a secondary method of oil production. This technology is aimed, on the one hand, at reservoir pressure maintenance (RPM), and, on the other, at enhancing oil recovery and intensifying oil production. The negative consequences of non-stationary waterflooding can be the premature watering of the produced wells and the imbalance of the reservoir pressure maintenance system, as well as the formation of stagnant and weakly drained zones of the reservoir with residual reserves of hard-to-recover oil.Aim. To improve the efficiency of non-stationary waterflooding under the conditions of high geological and anthropogenic heterogeneity of oil and gas reservoirs in a floating oil reservoir propped up by edge and bottom waters.Materials and methods. We used geological and field information collected on the site of the AB1-2 development object of the Kechimovskoye field in the Western Siberian region. A new methodological approach to optimizing the process of non-stationary waterflooding under complicated conditions of geological and anthropogenic heterogeneity is proposed, including the construction of an improved geological model and the solution of a number of experimental problems using the Hurst method, the Pareto distribution principle and the theory of catastrophes.Results. Using a new version of the geological model of the area of the AB1-2 development object of the Kechimovskoye field and the available geological and field information, we clarified the position of the oil-water contact (OWC) and the correlation of the well section, taking into account the working intervals of production and injection wells. Geological and technical measures were formulated to improve the efficiency of the object under development.Conclusions. An effective development of the geologically complex AB1-2object of the Kechimovskoye field is impossible without updating its geological model. Such updating should be aimed at determining the location of residual reserves in the area and section of the reservoirs, identifying the regularities of the mechanism of oil reserve recovery, assessing the efficiency of the reservoir pressure maintenance system, and developing complex geological-technological measures for achieving the approved value of the final oil recovery factor. The expected efficiency of the proposed optimization methodology provides for additional oil production, a reduction in the flow rate of injected and withdrawal of produced water.