A multiscale study of density-driven flow with dissolution in porous media

Abstract In the present work, a suite of numerical experiments with linear stability analysis are conducted to study density-driven flow with chemical dissolution of two reactive fluids in synthetic porous media. Linear stability analysis at the Darcy scale is first performed to predict the interfacial phenomena and instability at the initial time. Pore-scale simulations using the lattice Boltzmann method (LBM) are further conducted to capture more mechanistic information and advance the understanding of the transport processes. Under different scenarios, it is demonstrated that the transport processes exhibit distinct behaviors, which are largely dominated by the interplay among density contrast, chemical reaction rate and evolution of the porosity/permeability. All the results indicate that the interfacial instability can be triggered by the density contrast between two miscible fluids, leading to the Rayleigh-Taylor (R-T) instability. The R-T instability can be suppressed by the heterogeneous surface reaction between the fluid and solid phases, which prevents the transport of the denser fluid. Over the long term, it is found that the interfacial instability is influenced by the evolution of the porosity/permeability due to dissolution, which potentially restarts the transport of the denser fluid.