Visualization and Analysis of CO2 Permeation Process in a Porous Media by Microfocus X-Ray Computed Tomography

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Carbon capture and sequestration (CCS) is part of the global challenge of mitigating global warming and climate change. Geological sequestration of carbon dioxide (CO2) is an immediately available and technologically feasible method for achieving a substantial reduction in carbon dioxide emissions into the atmosphere. Because the density of CO2 is lower than that of water, injected CO2 migrates upward in an aquifer owing to the buoyancy force. Therefore, a highly impermeable layer is generally employed to prevent CO2 leakage from the storage reservoirs. For these reasons, assessment of the storage site, leakage risks, and storage costs are one of the main issues in CO2 geological sequestration. The intent of the present study was to clarify the fundamental mechanism of CO2 migration in a reservoir. The behaviour of liquid CO2 in water-saturated silica packed bed was observed using high spatial resolution X-ray computed tomography. As the result, CO2 behavior in the water saturated porous structure was visualized with 20 μm resolution, and it was found that the permeation and distribution of liquid CO2 were strongly dominated by the local pore size and its structure.