A coupled lattice Boltzmann model for simulating reactive transport in CO2 injection

• A lattice Boltzmann model is proposed to describe the geochemical reactions during CO2 injection.
• The interaction between geochemical reactions and solute advection–diffusion processes is numerically investigated.
• Porosity change and impacts on flow field are studied, and furthermore figure out their numerical relationship.

A lattice Boltzmann method (LBM) based computational REV model of geochemical reaction is proposed to describe the geochemical reactions of both solute ions transport and solid phase CaCO3 dissolution in CO2-saturated water as well as their effects on the velocity fields of fluid flows during a CO2 injection process. This includes the porosity change with the calcium carbonate dissolution and its feedback impacts on fluid flows. The proposed model is implemented in our in-house LBM code and verified through a hypothetic numerical experiment. The interaction between chemical reactions and fluid advection–diffusion processes is investigated through comparing simulation results of different species distribution at different stages. It has been well known that even a small porosity change induced by the chemical reaction would cause an obvious permeability change. Our present results validate that rule, and furthermore yield a numerical relationship between porosity change and fluid velocity increase at different time steps. This demonstrates that the proposed LBM geochemical reaction model may serve as a reliable approach to investigate the reactive transport in reservoirs of CO2 injection.