摘要：The relative permeabilities of CO<sub>2</sub> and brine are important parameters that account for two-phase flow behavior, CO<sub>2</sub> saturation distribution, and injectivity. CO<sub>2</sub>/brine relative permeability curves from the literature show low endpoint CO<sub>2</sub> permeability values and high residual brine saturation values. These are the most distinguishing aspects of the CO<sub>2</sub>/brine relative permeability from oil/water and gas/oil. In this study, this aspect is investigated experimentally by employing a wide range of CO<sub>2</sub> injection flow rates. As a result, all the measurements align with previous studies, having low endpoint relative permeability and high residual brine saturation values. They have obvious relationships with the changes in CO<sub>2</sub> flow rates. As the CO<sub>2</sub> flow rate increases, the endpoint relative permeability increases, the residual brine saturation decreases, and they converge to specific values. These imply that a high CO<sub>2</sub> injection flow rate results in high displacement efficiency, but the improvement in efficiency decreases as the flow rate increases. The reasons are identified with the concept of the viscous and capillary forces, and their significance in the CO<sub>2</sub> injection into a reservoir is analyzed.
