Use of Analog Two-Phase Relative Permeability Data to Estimate Drainage CO₂/Brine Relative Permeability Curves

Relative permeability is a crucial parameter for modeling multiphase flow in porous media. However, experimental data on CO2/brine relative permeability are scarce and often inconsistent due to experimental challenges such as solubility and water evaporation. As a result, most of the available CO2/brine relative permeability data cover the early stages of the relative permeability curve, because high gas relative permeabilities during the drainage process are difficult to achieve. In this study, we propose a novel approach to estimate the drainage CO2/brine relative permeability curve from analog fluids and available CO2/brine relative permeability data. Finally, we integrate pore-scale-modeling simulations to gain additional insight and propose a workflow to use the analog fluid relative permeability curves to supplement CO2/brine relative permeability curves. We validate our approach by systematically comparing CO2/brine relative permeability curves with other fluid pairs and demonstrate that we can capture the key features and trends of the CO2/brine relative permeability behavior. Our method provides a simple and promising workflow to use routine fluid systems to predict CO2/brine relative permeability, in which experimental measurements are more challenging.