Numerical simulation with adaptive finite element methods for CO2 storage in saline aquifers

A high-resolution numerical simulation of DDC (dissolution-diffusion-convection) process is one of the main challenges for CO2 storage in saline aquifers. This paper mainly describes a variable-density single-phase incompressible model and develops the numerical simulation of the DDC process using an adaptive finite element method. The present algorithm, which is used to conduct high-resolution studies on DDC process, has second-order accuracy. We study the behaviors both at the onset time of convection and during the whole process. It is found that the onset time, the critical wave-length and the critical depth of diffusive layer follow closely the prediction of linear stability analysis. In addition, CO2 mass flux at the top boundary, which gives the rate of CO2 dissolved into a negatively buoyant aqueous phase, is found to be proportional to Rayleigh number. Furthermore, the relations between fluctuation and the onset time, the critical depth of diffusive layer and the critical CO2 mass flux are determined by the present numerical results, which are mentioned for the first time.