Thermo-convective carbon sequestration in horizontal porous layers

This article explores the linear and nonlinear stability of double-diffusive density-driven convection in the context of carbon sequestration in deep saline aquifers. The anisotropy, due to the thermal and solutal diffusivities, is considered in a porous layer where the permeability is assumed to be layer dependent. Solute concentration is assumed to decay via a first-order chemical reaction. It is observed that varying the ratio of vertical to horizontal solutal and thermal diffusitivies does not significantly affect the behaviour of linear instability. This is in contrast to the nonlinear stability results. It is also observed that when the solute and thermal diffusion rates dominate the solute and thermal reaction rates, a change in the permeability has no significant effect on the onset of convection. However, when the solute reaction rate dominates the diffusion rate, a change in permeability has a notable effect on the instability of the system. It is observed that the effects of geothermal gradient on the onset of convection are negligible as compared to the solutal effects induced by the diffusion and dissolution of CO2 in deep saline aquifers.