2005 Volume 47 Issue 1 Pages 65-80
The carbon fixation by water-rock reactio n s (mineral trapping) in the sequestration of carbon dioxide into the aquifer is investigated based on dissolution kinetic model. The simulation is performed by using the mineralogical and chemical data of the host rocks (sedimentary and igneous rocks) and formation water (freshwater and saline water) in the Boso Peninsula, Chiba, Japan and injecting a constant CO2. The model result indicates that mineral trapping is successful for fixation of carbon as carbonate minerals in hundred thousand years in the cases for not only sedimentary rocks (mudstone and sandstone) but also igneous rock (serpentinite). The proportion of the amount of fixed carbon to the injected CO2 into the groundwater becomes larger as the amount of the carbonate minerals in host rock and/or of the released Ca' and Mg2+ by dissolution of silicate minerals is smaller. However, the proportion is not significantly influenced by chemical composition of initial groundwater and grain size. It indicates that it is important for CO2sequestration into the aquifer to confirm the amount of carbonate minerals and silicate minerals including Ca2+ and Mg2+ in host rocks. Concerning the time scale to fix carbon as carbonate minerals, it is estimated that it takes approximately 105 years to complete the mineral trapping when field dissolution rate constant data are used.
