title: Reactive-convective dissolution in a porous medium: the storage of carbon dioxide in saline aquifers.
abstract: We quantify the destabilising effect of a first-order chemical reaction on the fingering instability of a diffusive boundary layer in a porous medium. Using scaling, we show that the dynamics of such a reactive boundary layer is fully determined by two dimensionless groups: Da/Ra2, which measures the timescale for convection compared to those for reaction and diffusion; and βC/βA, which reflects the density change induced by the product relative to that of the diffusing solute. Linear stability and numerical results for βC/βAin the range 0-10 and Da/Ra2in the range 0-0.01 are presented. It is shown that the chemical reaction increases the growth rate of a transverse perturbation and favours large wavenumbers compared to the inert system. Higher βC/βAand Da/Ra2not only accelerate the onset of convection, but crucially also double the transport of the solute compared to the inert system. Application of our findings to the storage of carbon dioxide in carbonate saline aquifers reveals that chemical equilibrium curtails this increase of CO2flux to 50%.
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, Cambridge, UK. sssc1@cam.ac.uk and Department of Chemical Engineering, Jadavpur University, Kolkata-700032, India.
authors.forename: Parama
authors.initials: P
authors.lastname: Ghoshal
authors.affiliation: Department of Chemical Engineering, Jeju National University, Jeju-63243, Republic of Korea.
authors.forename: Min Chan
authors.initials: MC
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, Cambridge, UK. sssc1@cam.ac.uk.
authors.forename: Silvana S S
authors.initials: SS
authors.lastname: Cardoso