Study on the Displacement and Gas Storage Characteristics of Flue Gas Gravity Flooding in Fractured Tight Oil Reservoirs

Flue gas is an industrial waste gas produced by the combustion of fossil fuels. Its application in reservoir development can increase oil recovery factor and achieve underground storage of CO2. Flue gas gravity flooding experiments were conducted to clarify the displacement and storage characteristics of flue gas gravity flooding. The results show that the experiment can be divided into three stages based on the output characteristics, and the oil recovery factor curve exhibits a stepwise increase. During the pure oil production stage, the crude oil output is approximately half of the total output. When the experimental pressure is 18 MPa, the oil recovery factor is 11.53%. As the experimental pressure increases, the extraction and viscosity reduction effects of the flue gas are enhanced. Therefore, the oil recovery factor gradually increases and the crude oil in the micropores and small pores is better displaced. The storage rate of flue gas is 8.42% at a pressure of 18 MPa. When the experimental pressure increases to 25 MPa, the storage rate of flue gas reaches 19.70%. The increase in permeability and the extension of displacement time can effectively improve the oil recovery factor. The research results provide a new approach for the resource utilization of flue gas and offer theoretical support for flue gas flooding in tight reservoirs.