Numerical simulation of sealing effect of gas hydrate for CO2 leakage in marine sediment

Abstract:

Although carbon dioxide capture and storage in subsea geological structure is regarded as one of the promising mitigation technologies against the global warming, there is a risk of CO2 leakage and it is required to develop numerical models to predict how the CO2 migrate in the marine sediments. It is said that there are CO2-trap mechanisms in the geological formations, such as capillary trap, dissolution trap, and mineral trap. In this study, we focus on another trap mechanism: namely, hydrate trap. If the water is deep in the ocean, say more than 250 m, CO2 hydrate forms near the sea floor, at which temperature and pressure conditions can stabilise CO2 hydrate. To predict the gas productivity, it is important to know permeability damage in hydrate bearing sediments. Although hydrate saturation is the same, the permeability is different depending on its spatial distribution within the pore of sand sediment. Here, to know where hydrate is formed in the pore of porous media, we propose a numerical model for estimating the microscopic distribution of CO2 hydrate in sand sediment using a classical nucleation theory and the phase-field model.