Steady-State Supercritical CO2 and Brine Relative Permeability Measurements at Different Pressure Conditions

Relative permeability is one of the most important properties influencing the transport of CO2 in the subsurface and is a key input for dynamic simulation. This study reviews an experimental program designed to develop best practices for supercritical CO2 and brine (scCO2-brine) relative permeability tests and to gather insights on scCO2-brine flow behavior. Significant system and procedural upgrades (such as upgraded materials, larger gas pumps, fluid equilibrium, and differential pressure controls) are implemented to overcome operational challenges associated with scCO2-brine systems. We measure both drainage and imbibition relative permeabilities using the steady-state method on a single Berea sandstone core at two pore pressures (12.4 and 30 MPa [1,800 and 4,350 psi]). The use of a recirculating steady-state system with equilibrated fluids at pressure and temperature is key to enabling high-quality data collection in scCO2-brine relative permeability tests. The results demonstrate no significant difference in relative permeability behavior between the two pressures during the drainage cycle. No pressure effects are observed on scCO2-brine relative permeability behavior, and no wettability effects are inferred. Additionally, the drainage and imbibition relative permeabilities follow the strongly water-wet displacement behavior with no observed hysteresis in water relative permeability (Krw) and gas relative permeability (Krg). These results contribute to the best practices for scCO2-brine relative permeability measurements and flow behavior for CO2 storage projects.