Reduction of greenhouse gas emissions into the atmosphere and utilization of carbon dioxide (CO2), including through production wells, is an urgent task not only from the environmental point of view, but also as a method of flow stimulation. Periodic injection of carbon dioxide into production wells is referred to in the literature as the Huff and Puff technology/method. The efficiency of the technology is achieved mainly by reducing oil viscosity and volumetric expansion of oil, as well as reducing interfacial tension and residual oil saturation. However, the relative contribution of each of the factors and the possibility to optimize the process by increasing the effect of these components are rarely described in the literature. It is quite often mentioned that one of the effects of treatment is swelling of oil as a result of saturation and dissolution of CO2 in it. It is difficult to attribute this physical process to actually affecting additional oil. Since an increase in the volume factor reduces oil reserves in terms of standard conditions, and the gasification of oil in the reservoir and its subsequent separation in the field do not increase the final marketable mass of the product and commercial additional production. Many of such issues are debatable due to the lack of practical experience with CO2 injection. This paper analyzes the key physical factors affecting the efficiency of CO2 injection technologies. Analytical calculation is performed on a synthetic example in one of the commercial simulators, where a reservoir saturated with high-viscosity oil with low gas content is taken as an object of research. The processes occurring in the model when implementing the Huff and Puff technology is described, the dynamics of changes in the main parameters is given, quantitative assessment is given and some features of the additional production behavior are explained.
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