The Effect of Pressure and Temperature on Brine-CO₂ Relative Permeability and IFT at Reservoir Conditions

Geologic sequestration of CO₂ in deep saline aquifers has emerged as a technology with the greatest potential to economically sequester large quantities of CO₂ from a wide range of industrial operations for greenhouse gas mitigation. The displacement characteristics of CO₂ injected into deep saline aquifers are essential because they control both the migration of CO₂ and the available pore space in the reservoir at irreducible saturation conditions. This paper presents the steady-state brine-CO₂ relative permeability measurements in a sandstone core under CO₂ flooding conditions versus pressure and temperature. The results indicate a strong correlation between pressure and the endpoint relative permeability to CO₂. As the pressure increased from 1200 psi to 2600 psi, the end point relative permeability to CO₂ increased from 32.4% to 46.8%. Temperature was found not to strongly affect the relative permeability, although the end point relative permeability to CO₂ decreased with temperature increase from 31.05°C to 38°C. This paper also describes the effects of pressure and temperature on the interfacial tension (IFT) between CO₂ and brine. The IFT was observed to decrease as pressure increased and increase as temperature increased. These data will provide useful information to evaluation, analysis, and optimization of CO₂ sequestration in deep saline aquifers.