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

Abstract

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.