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Reactive-convective dissolution in a porous medium: the storage of carbon dioxide in saline aquifers

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Ghoshal, P 
Kim, MC 
Cardoso, SSS 

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/βA in the range 0–10 and Da/Ra2 in 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/βA and Da/Ra2 not 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 CO2 flux to 50%.

Description

Keywords

0306 Physical Chemistry (incl. Structural)

Journal Title

Physical Chemistry Chemical Physics

Conference Name

Journal ISSN

1463-9076
1463-9084

Volume Title

19

Publisher

Royal Society of Chemistry
Sponsorship
P. G. gratefully acknowledges the Dr Manmohan Singh Scholarship from St. John's College, Cambridge and the grant of study leave from Jadavpur University, Kolkata, India.