Simulation of CO2 injection in a small-scale pilot site in the Pohang Basin, Korea: Effect of dissolution rate of chlorite on mineral trapping

摘要

Korea, a small-scale pilot project for CO2 injection was launched to target an offshore reservoir within the Pohang Basin. The objectives of this study are to present the effects of CO2 injection in a slopingaquifer on the evolution of the CO2 plume and its impact on mineral trapping using TOUGHREACT. Theresults show that the CO2 plume is asymmetrical and rapidly migrates along the slope in the up-dipdirection from the injection well. With the migration of the CO2 plume, the increased acidity accelerates the water-rock interactions. As the CO2-water-rock interactions start quickly due to the rapid spreading of the CO2 plume, the amount of mineral trapping slightly increases due to the precipitation of sideriteby chlorite dissolution. However, the stability of siderite is sensitive to the dissolution rate of chlorite. At low chlorite dissolution rates, siderite is more stable than ankerite in an undersaturated state. Athigh chlorite dissolution rates, ankerite is more stable because of the higher pH. In addition, the amount of mineral trapping increases considerably up to 3.7 kg/m(3), which is about 90 times that at the initial rate ( 0.04 kg/m(3)). This simulation indicates that the uncertainty in the dissolution rate of chlorite mustbe considered when estimating the capacity of mineral trapping in situations in which iron-containing carbonate minerals significantly influence the mineral trapping. (C) 2017 Elsevier Ltd. All rights reserved.