Understanding Evolution of Mineral Reactive Surface Area for Improved Prediction of Mineral Reaction Rates in Porous Media

Abstract:

Understanding mineral reaction rates in porous material is crucial in many environmental systems such as natural weathering process, CO₂ capture, storage (CCS), and CO₂ enhanced oil recovery (CO₂-EOR) etc. Prediction of in-situ mineral reaction rates is challenging, and a significant variation is observed between laboratory data compared to field data due to factors like variation in the physicochemical properties of minerals, spatial heterogeneities, chemical composition of the fluid, etc. Previous studies have suggested that this discrepancy is mostly due to the imprecision in determining the mineral reactive surface areas. Even in many cases, the evolution of surface areas of different mineral phases during the reaction gets ignored. In this study, a sandstone sample from the Bandera Brown formation is reacted with CO₂ saturated brine to understand the alteration of mineral reactive surface areas. Crushed rock sample is experimented with 1 M NaCl solution in a batch reactor where CO₂ is injected at elevated temperature (50º C) and pressure (100 bar) to mimic the subsurface condition. The BET surface area is determined by N₂ gas adsorption using the Quantachrome surface analyzer; SEM-EDS and XRD analysis have provided details mineralogical information of the sample. Finally, a reactive transport simulation is carried out in CrunchFlow to compare the mineral dissolution rates using different reactive surface areas derived from literature and experiments.