Evaluation of the Impact of Water Injection on CO2 Dissolution and Migration Characteristics during Sequestration

This work investigates CO2 dissolution and migration in a homogeneous aquifer through a vertical well at different water injection rate and ascertains the amount of CO2 sequestered into the subsurface. Numerical simulation was done with Computer Modelling Group (CMG) simulator and builder used to write the dataset and validated with GEM.WINPROP was used to predict the thermodynamics properties using the Peng-Robinson 1978 EOS and sensitivity studies carried out with three different water injection rate (25, 50 and 75m3/day) and compared to a base condition of no water injection. Result indicates that after 196 years, mobile CO2 gas cap formation was at the top of the formation with a saturation of 0.99 and length of 558.4753m, 75604384 moles of CO2 dissolved and 18547034 moles of CO2 trapped without water injection above the CO2 injector. For 25m3/day of water injected, there was a 54 % decrease in the length of gas cap saturation, 17% decrease in the CO2 dissolved and 28% decrease in the CO2 trapped when compared with the base case model without water injection. 50m3/day scenario of water injected had 93% decrease in the length of gas cap saturation, 39% decrease in the CO2 dissolved, and 63% decrease in the CO2 trapped. Also, 75m3/day of water injected above the CO2 injector shows no zone of mobile supercritical CO2 formed at the top of the structure with 50% decrease in the CO2 dissolved and 64% decrease in the CO2 trapped .Result reveals that most of the injected CO2 were completely dissolved in water and less trapped at different rate of water injection.