Experimental and theoretical investigations of CO₂ injectivity

Abstract

Laboratory sandstone core flooding experiments were conducted to investigate the impact of brine desaturation and salt precipitation on $CO_{2}$ injectivity. An attempt was then made to reduce the impact of salt precipitation on $CO_{2}$ injectivity by injecting a slug of diluent prior to $CO_{2}$ injection. The effect of brine salinity, $CO_{2}$ injection rate and initial core permeability on the efficacy of this mitigation technique was investigated. Decrease in diluent brine salinity improved injectivity but there exist a critical brine salinity below which $CO_{2}$ injectivity was further impaired. It was also observed that, above a certain $CO_{2}$ injection rate, alternating $CO_{2}$ injection with the diluent brine could not enhance $CO_{2}$ injectivity. Injectivity improvement also depends on initial permeability of the porous medium. Up to about 30% injectivity improvement was observed in the experiments.