With a potential capacity of sequestrating 4,000 – 23,000 Gt of CO_2, geological carbon sequestration which works by storing captured and compressed CO₂ into geological formations such as saline aquifers has been attracting elevating attention during the past two to three decades as a strategy for mitigating global warming. After being injected into the target formations that are comprised of porous media, the bulk CO₂ phase will firstly become disconnected and trapped in the pore space during the reinvasion of the background flow (‘capillary trapping’); with further invasion of brine capillary trapped CO₂ are dissolved (‘dissolution trapping’), reducing the risk of CO₂ leakage from the aquifers. Therefore, to improve the security of geological carbon sequestration, it is of importance to understand the evolution of capillary trapped CO₂ during the process of dissolution trapping, both qualitatively and quantitatively.

Due to the opaque formations of porous media, direct optical access of in-situ fluid configuration is impossible, while with the advances of microtomographic imaging (MCT) information of fluid and the inner structure of porous media can now be visualized as microtomographic data. With subsequent data processing, physical properties of the system such as the volume and the surface area of fluid can be obtained for further data analysis. In this talk, I will be presenting the time-evolution of CO₂ clusters ‘tracked’ using MCT throughout a series of dissolution experiments that were conducted under the conditions for geological carbon sequestration. To quantitatively understand the process of CO₂ dissolution, the mass transfer coefficient k which measures the rate of CO₂ mass transferred into the brine is calculated and presented for the dissolution experiments; the complexities for calculating k are also discussed. With the calculated k, method of back calculating the in-situ CO₂ concentration field is also proposed.

Join the Zoom Meeting
Meeting ID: 820 8749 8368
Password: 066 045