Development and current state of non-stationary flooding of oil reservoirs

Abstract

Relevance. The development of reserves of readily available low-viscosity oil increases the share of current reserves of high-viscosity oil and deposits with complex geological structures, which leads to a decrease in oil production. Therefore, over the past 10 years, oil production in Western Siberia has decreased by 10%. The share of water in the volume of liquid extracted from oil wells (watercut) is growing and in Western Siberia at the beginning of 2025 is 90% with a relatively low oil recovery coefficient of 38%, and therefore the search for cheap and effective methods to increase oil recovery or modifications of existing methods is an urgent task. Aim. To conduct a review of the development of cyclic flooding methods and changes in the direction of filtration flows, which are generally referred to as non-stationary flooding; to show the current state of use of these increase oil recovery methods; describe and compare the models and techniques used to select the sites where the implementation of increase oil recovery data is expected to have an effect. Methods. Comparison, retrospective analysis. Results and conclusions. The paper describes the disadvantages and advantages of two models of cyclic flooding. It is shown that the models take into account only the properties of the reservoir, the properties of fluids are not taken into account. The paper describes two methods for selecting sites for non-stationary flooding, it is shown that the methods for selecting sites are suitable for the direction of filtration flows method, for the cyclic flooding method, half-cycles of pumping stop do not take into account the actual rate of absorption of water embedded in a low-permeable layer. But even for direction of filtration flows method, the existing techniques do not take into account the configuration of stagnant oil zones, and the direction of filtration flows may change, but not towards stagnant zones, and therefore the increase oil recovery effectiveness may be insignificant. The review shows that cyclic flooding is studied mainly in Russia and China, with asynchronous cyclic flooding and polymer cyclic flooding being studied most intensively. The review provides a summary of the use cyclic flooding in Russia (over the past 3 years) and abroad. For citation: Telegin I.G., Grachev S.I. Development and current state of non-stationary flooding of oil reservoirs. Bulletin of the Tomsk Polytechnic University. Geo Assets Engineering, 2026, vol. 337, no. 9, pp. 200–217. http://doi.org/10.18799/24131830/2026/9/5238