Characterizing Formation Damages Due to Carbon Dioxide Injection in High Temperature Reservoirs and Determining the Effect of Solid Precipitation and Permeability Reduction on Oil Production

摘要

Carbon dioxide injection and its performance during sequestration activities rely on the ability of the injection well to inject the desired amount of CO2 for decades. However, the CO2-rock-water interaction may cause immense formation damage by plugging the pores and reducing the permeability. Its severe consequences will reduce oil and gas productivity and CO2 injectivity in the reservoir. In this study a numerical simulator is developed and it solves the fluid flow equations, chemical reactivity equations, particle transport and particles deposition equations to predict the amount of formation damage during CO2 injection. We found that it has high rate of chemical reactivity and dissolution of reservoir rock near the wellbore. The dissoluted reservoir rock particles get precipitated in the reservoir away from the injection well, plugging the pores and reducing the formation permeability. From the simulation result on the effect of reservoir depth and temperature, we found that deep oil and gas reservoirs are good candidates for CO2 sequestration than shallow reservoirs. Because the increased depth and temperature of a deep reservoir decrease the CO2 dissolution rate and lower the solid precipitation. Sensitivity analysis of CO2 injection rates was performed to identify the effect of CO2 injection rate on reduced permeability in deep and high temperature formations. It was found that increased CO2 injection rates and pressures enable to reach miscibility pressure. Once this pressure is reached, there are less benefits of injecting CO2 at a higher rate for better pressure maintenance, no further diminution of residual oil.