Carbon Geological Storage

Abstract Today’s energy concerns reflect the large anticipated increase in demand within the next generation, the current dependency on fossil fuels and climate implications, the geographic mismatch between resources and demand, and the disparity in associated time scales. The long-term geological storage of vast quantities of CO2 is a relatively new scientific and technological challenge, plagued with underlying coupled hydro-chemo-mechanical processes and potential emergent phenomena. Processes include: capillarity, density and viscous effects on flow; acidification, mineral dissolution, and ensuing changes in permeability; phase transformations (and CO2-CH4 exchange in hydrates); and stress changes. These processes are involved in the analysis of CO2 storage in saline aquifers, coal seams, depleted reservoirs, and in clathrates. Furthermore, the understanding of underlying processes guides monitoring (active: seismic and electromagnetic; passive: seismic, deformation, thermal) and may lead to improved efficiency and leakage-sealing strategies. Dimensionless ratios help identify the domain for the various dominant processes that govern CO2 geo-storage.