This article deals with the issues of enhanced oil recovery in terrigenous reservoirs characterized by structural heterogeneity in both the section and along the strike. As a working oil displacing agent, high-pressure gas is used, which is more effective than water-based solutions. The mechanism of the formation of the transition zone in the area of gas mixing with oil is shown and the empirical dependence of the sizes of the transition zone on the length of the linear displacement section and the viscosity ratio of oil and gas in reservoir conditions is established. Information is given on testing a high-pressure gas injection method in the conditions of the Goit-Kort field (CR). It is shown that the introduction of the method allowed to increase the current oil production and oil recovery coefficient in the field.