화학공학소재연구정보센터
Transport in Porous Media, Vol.90, No.3, 807-829, 2011
Sensitivity Study of Simulation Parameters Controlling CO2 Trapping Mechanisms in Saline Formations
The primary purpose of this study is to understand quantitative characteristics of mobile, residual, and dissolved CO2 trapping mechanisms within ranges of systematic variations in different geologic and hydrologic parameters. For this purpose, we conducted an extensive suite of numerical simulations to evaluate the sensitivities included in these parameters. We generated two-dimensional numerical models representing subsurface porous media with various permutations of vertical and horizontal permeability (k(v) and k(h)), porosity (phi), maximum residual CO2 saturation (S-gr(max)), and brine density (rho(br)). Simulation results indicate that residual CO2 trapping increases proportionally to k(v), k(h), S-gr(max) and rho(br) but is inversely proportional to phi. In addition, the amount of dissolution-trapped CO2 increases with k(v) and k(h), but does not vary with phi, and decreases with S-gr(max) and rho(br). Additionally, the distance of buoyancy-driven CO2 migration increases proportionally to kv and rho(br) only and is inversely proportional to k(h), phi, and S-gr(max). These complex behaviors occur because the chosen sensitivity parameters perturb the distances of vertical and horizontal CO2 plume migration, pore volume size, and fraction of trapped CO2 in both pores and formation fluids. Finally, in an effort to characterize complex relationships among residual CO2 trapping and buoyancy-driven CO2 migration, we quantified three characteristic zones. Zone I, expressing the variations of S-gr(max) and k(h), represents the optimized conditions for geologic CO2 sequestration. Zone II, showing the variation of phi, would be preferred for secure CO2 sequestration since CO2 has less potential to escape from the target formation. In zone III, both residual CO2 trapping and buoyancy-driven migration distance increase with k(v) and rho(br).