Evaluating CO2 Storage Potential in Serra Geral Basalts, São Paulo, Brazil

Abstract Basalt formations have emerged as a promising option for large-scale Carbon Capture and Storage (CCS), leveraging their capacity to permanently sequester CO2 through mineral carbonation. This study evaluates the CO2 storage potential of the Serra Geral basalts in São Paulo State, Brazil, by combining porosity estimation, spatial thickness analysis, and Monte Carlo simulations. A novel empirical equation, derived from 611 experimental measurements of P-wave velocity (Vp) and porosity across diverse basalt facies worldwide, enabled the estimation of porosity from geophysical logging data. To propagate the uncertainty inherent in porosity estimates and capture natural heterogeneity, Monte Carlo simulation was employed by sampling porosity values from a normal distribution defined by the observed mean and standard deviation. This stochastic approach generated multiple realizations of the total porous volume, providing a probabilistic estimate of the CO2 storage capacity. Results demonstrated the feasibility of storing millennia-worth of São Paulo's industrial CO2 emissions, underscoring the suitability of basalt formations for long-term sequestration in alignment with climate goals. The approach accounts for spatial variability in porosity related to basalt heterogeneity and weathering processes while emphasizing the importance of stochastic modeling to address data limitations. This study contributes to the growing evidence supporting basaltic CCS and provides scalable methodologies for preliminary assessments in data-scarce regions. The findings underscore the critical role of basalts in global carbon mitigation efforts and serve as a foundation for more detailed investigations that integrate fluid-rock interactions, operational factors, and monitoring protocols to optimize sequestration strategies.