Convective dissolution of CO₂ in saline aquifers: Progress in modeling and experiments

The dissolution of carbon dioxide (CO₂) in deep saline aquifer water is recognized as one of the fundamental mechanisms in the subsurface for storing significant quantities of CO₂. One fundamental physical effect of CO₂ dissolution is the slight increase in water density in the layer in contact with the buoyant free-phase CO₂ plume. Under specific conditions, this may lead to gravitational instability and the onset of free convection, significantly accelerating the dissolution of the free-phase CO₂ by bringing CO₂ in contact with a larger volume of aquifer water. It is also feasible to enhance CO₂ dissolution using engineering methodologies such as injecting water on top of the plume of CO₂. The objective of this review is to provide a perspective on the progress in modeling and experimental observations of physical aspects of CO₂ dissolution in deep saline aquifers. We review the published research efforts concerning the physical effects of CO₂ dissolution in formation water, the conditions under which process can be accelerated either naturally, such as by free convection, or by use of engineering methodologies, and the effects of CO₂ dissolution on CO₂ storage. Finally, we discuss areas in need of further research.