Reactive transport modeling (RTM) has been widely applied to improve our understanding of complex chemical/physical processes involving reactive fluid–rock interactions in subsurface systems and to provide insights into their possible regulation and management strategies. Yet, estimation of the mineral reactive surface areas in geologic media remains one of the key challenges limiting the accuracy of RTM predictions of subsurface processes, especially those that control the fate of carbon dioxide (CO2) during geologic CO2 storage. Many attempts have been made to combine imaging and experimental techniques to estimate mineral reactive surface area for use in RTMs of sedimentary reservoirs. However, these techniques have yet to be adapted to basaltic reservoirs, which have demonstrated immense promise for rapid carbon mineralization, but have significantly different pore structure, mineralogy, and chemical composition from their more often studied sedimentary counterparts. In this study, we address this issue by quantifying pore-accessible mineral surface areas through image analysis of high-resolution (500nm) scanning electron microscope (SEM) backscatter electron images of a basaltic rock sample from the Eastern Snake River Plain, Idaho. To evaluate whether the determined pore-accessible mineral surface area accurately reflects the reactive surface area, a continuum-scale RTM was developed from the high-temperature, high-pressure flow-through core experiment performed on the basalt sample by Luhmann et al. (2017). The model fits the experimental effluent chemistry when the pore-accessible mineral surface areas derived from the SEM image analysis are used. The extension of the core-scale model to the reservoir-scale and the parametrization of its mineral surface areas under a different CO2 injection scheme (Supercritical, WAG, and CO2-water co-injection) demonstrates that using the accessible surface areas of the reactive minerals present in the basalt rock is needed to accurately scale the rate constants for quantitative prediction and ultimate control of CO2 injection and mineralization in basaltic aquifers.

Investigation of accessible reactive surface area for improved prediction of CO2 mineralization in basaltic aquifer rocks

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.