Present Status of Studies on Water-Rock Interactions Associated with CO2 Geological Sequestration and Perspective on Kinetic Approach

This paper reviews the present status of studies on water-rock interactions associated with the geological sequestration of carbon dioxide (CO2), and stresses the need for a more realistic kinetic approach. Most studies on CO2-water-rock systems based on laboratory experiments, numerical simulations, and natural analogues suggest the fixation of injected CO2 in formation water as stable minerals. However, these results assume the formation of final equilibrium phases by chemical thermodynamics. The slow geochemical reactions and their reaction pathways should also be considered for a detailed prediction of the time scales needed for CO2 fixation. The slow reaction rates, uncertainty about reactive surface area, and difficulty of controlling surface and environmental conditions are major problems associated with this kinetic approach. Phase-shift interferometry (PSI), which observes the surface topography of minerals at the nanoscale level, has the potential to overcome some of the above difficulties for determining the precise dissolution rates of minerals with knowledge of surface topography.