The technology of CO2 injection into oil reservoirs contributes to a significant increase in oil production effectively reducing greenhouse gas emissions into the atmosphere. The mechanism of enhanced oil recovery was studied on the example of large formations of the Ordos Basin. The Ordos shale oil field is characterized by low porosity, low permeability and high reservoir heterogeneity. In this paper; based on an experimental model, a mechanism of filtration of fluid in a formation rock is proposed. To verify the model, oil recovery parameters were studied experimentally during CO2 injection for the conditions of the YanChang field of the Ordos Basin. In the course of the experiments, on models of long cores of the rock, the effect of the rate and intensity of injection, the exposure time and well parameters on the displacement efficiency during cyclic injection were measured. The paper concludes that it is possible to use CO2 injection technology to improve the efficiency of oil recovery on reservoirs using the example of the YanChang field.