Department of Mathematics - Seminar on Applied Mathematics - Numerical study on the convection dynamics of CO2 in deep saline aquifer

Carbon Capture, Utilization, and Storage (CCUS) is one of the key and viable technologies to mitigate carbon emissions at large scale. Particularly, the sequestration of CO2 in deep saline aquifer has demonstrated great potentials for carbon storage. After injection, CO2 spreads under the barrier of the low-permeability cap rocks in a supercritical state due to buoyancy, and gradually dissolves into the top of saline brine to form a dense diffuse layer. This density stratification may lead to instability and subsequent convection in the system, which can enhance the mass transfer of CO2 into the brine (hydrodynamic trapping) and reduce the risk of leakage. Therefore, the understanding the dynamic behaviors of the CO2 mixture during this process is important for better prediction the capacity and safety of the storage.
In this talk, we will present our numerical studies on the flow dynamics of CO2 in saline aquifers at different scales. Particularly, we employ the lattice Boltzmann method (LBM) at the pore scale and the discrete unified gas kinetic scheme (DUGKS) at the Darcy scale to investigate the convection of CO2 due to density difference in saline brains under different scenarios. The effects of density difference, impurities, reaction, and fractures, on the convective mixing process of CO2 are analyzed. The results are helpful for understanding the fundamental mechanisms occurring in CO2 saline storage.