An integrated model for CO 2 hydrate formation in sand sediments for sub-seabed CO 2 storage

Abstract CO 2 capture and storage has been considered to be one of the most effective strategies against global warming, among which CO 2 storage in deep saline aquifers using the sealing effect of gas hydrate and CO 2 storage in the sub-seabed sand sediment in the form of gas hydrate are of great interest nowadays, due to the large capacity of CO 2 storage in sub-seabed sand sediments and low risk of CO 2 leakage. To access those two options, an integrated model for CO 2 hydrate formation, which includes hydrate formation rates on the gas front, on the hydrate film behind the gas front, and on the surface of the sand particles behind the gas front, is proposed in this study to predict hydrate formation morphologies in the sand sediment under the condition of gas-liquid two-phase flow. Then, numerical simulations of CO 2 hydrate formation in the sand sediment are conducted, and unknown parameters in the models are determined by comparing the simulation results with experimental data. The simulation results indicate that CO 2 hydrate formation on the hydrate film behind the gas front makes a great contribution to CO 2 hydrate saturation near the boundary, occupies the pore space of the sand sediment, and results in the permeability reduction and the blockage of the gas flow.