Integrated Geophysical and Mechano-Chemical Approaches to Assess CO2 mineralization in Basalt during Geological Carbon Storage

Basaltic formations are increasingly recognized as promising storage for long-term geological CO₂ sequestration through in situ mineral carbonation, where the injected CO₂ converts into stable carbonate minerals. While field and laboratory studies have demonstrated the feasibility of this process, substantial uncertainties remain regarding the geochemical controls on reaction rates, reaction pathways, and their coupling with evolving transport properties in basalt reservoirs. In particular, the interplay between mineral dissolution, secondary mineral precipitation, and reaction-induced microstructural evolution remains poorly constrained, limiting predictive assessments of storage efficiency and longevity. Our study proposes an integrated geochemical–geophysical framework to investigate CO₂–brine–basalt interactions under conditions relevant to geological storage, with a focus on reactive transport processes and associated mechano-chemical feedback phenomena. The primary objective is to determine how basalt mineralogy, pore structure, and fluid composition govern carbonation reactions, and how these reactions response on porosity, permeability, and reactive surface area through time. A central aim is to compare the roles of precipitation-induced pore clogging and reaction-driven cracking, which together control fluid accessibility and mineralization efficiency. The proposed approach integrates detailed mineralogical, hydromechanical, and geochemical characterization of basalt samples with controlled flow-through experiments using CO₂-saturated brines in a core flooding rig. These experiments are designed to track the temporal evolution of fluid chemistry and solid–fluid reactions while simultaneously monitoring changes in transport and elastic properties. The geophysical measurements used for monitoring the experiments include ultrasonic (P and S) wave velocities and attenuations and electrical resistivity, which will allow us inferring geochemically induced microstructural changes. We will discuss the geochemical and geophysical results of basalt samples from the pre and post brine-CO₂ flow test. Emphasis is placed on identifying dominant reaction pathways, the formation of secondary carbonate and silicate phases, and their spatial distribution within the rock matrix. This integrated framework aims to improve the interpretation of time-lapse geophysical monitoring signals in basaltic CO₂ storage reservoirs. By advancing a process-based understanding of mineral carbonation dynamics, this study addresses critical knowledge gaps related to reaction efficiency, transport limitation, seismic response, and monitoring sensitivity, thereby supporting the development of robust strategies for CO₂ sequestration in basalt complexes as long term climate mitigation strategy.