Effect of precipitation mineralization reactions on convective dissolution of CO2 : an experimental study

To analyze the influence of a precipitation mineralization reaction between dissolved CO₂ and calcium ions on the convective transfer of CO₂ towards an aqueous phase, the convective dissolution of CO₂ into aqueous solutions of calcium hydroxyde (Ca(OH)₂) and calcium chloride (CaCl₂) of various concentrations is studied experimentally. We show that different precipitation patterns develop in the aqueous solution depending on the nature and concentration of the reactant in the host phase. In the case of Ca(OH)₂, precipitation coupled to convection leads to vigorous convective mixing in the host phase and sedimentation of solid particles of calcium carbonate (CaCO₃) down to the bulk of the reservoir. Conversely, dissolution of CO₂ in buffered CaCl₂ solutions leads to a stabilisation of the buoyancy-driven convection due to a decrease in density and the adherence of the precipitate to the cell walls.