Determining the dominant factors controlling mineralization in three-dimensional fracture networks

Abstract

One methodology to reduce CO${}_2$ in the atmosphere is inject it into subsurface systems where the ambient conditions are favorable for the carbon to precipitate/mineralize thereby permanently trapping it. Prospective host rocks are relatively impermeable when intact, so the flow of fluids and associated reactive transport therein primarily occurs within and through interconnected fracture networks that provide lower hydraulic resistance. Although critically important for the success of carbon mineralization, the characterization of the interplay between network geostructure, geochemical reactions, and hydrology on the total extent of mineralization is poorly understood. To this end, a set of reactive transport simulations modeling coupled dissolution and precipitation under a variety for hydrological and geochemical conditions are performed to characterize their impact on mineralization in three-dimensional fractured media. The generated data set is used to perform a robust sensitivity analysis and characterize how model parameters, as well as the network structure, affect the total amount of precipitated mineral. It is observed that the reaction rate constant of gypsum, the volume of the network, the incoming volumetric flow rate, and initial porosity showed the strongest impact on the maximum amount of mineralization in the system throughout the simulations.