BATCH REACTION EXPERIMENTAL RESULTS AND REACTIVE TRANSPORT MODELING EVALUATION OF AQUEOUS CO2-BASALT REACTIVITY IN THE SNAKE RIVER PLAIN, IDAHO, USA

Geologic carbon mineralization by reacting CO₂-charged water with subsurface formations is identified as a method to store CO₂ and mitigate the impact of greenhouse gases on global climate. Specifically, mafic and ultramafic rocks are recognized for their reactivity and high potential to sequester carbon permanently as carbonate minerals. In the northwestern United States, two large volcanic provinces, the Columbia River Basalt (CRB) and the Snake River Plain (SRP) basalt, are identified as potential areas for large-scale carbon mineralization. Currently, researchers from Idaho National Laboratory and Chevron Technical Center, are evaluating the geochemical reactivity of basalts in the Eastern Snake River Plain (ESRP) in southern Idaho for carbon mineralization through a series of laboratory experiments and geochemical modeling.

To evaluate carbon mineralization rates of SRP basalt at reservoir conditions, a series of two-60+ day long tests with synthetic reservoir water, CO₂, and basalts were conducted at 20° and 40 °C with 15 bars and 45 bars of nominal CO₂ pressures. Periodic fluid samples were analyzed to determine the geochemical evolution of these systems. The experimental results show that the rates of basalt dissolution based on SiO₂ release are 1.5 and 1.9 times higher at 40° than at 20 °C for CO₂ pressures of 15 and 45 bars, respectively. These results have been incorporated into a reactive transport model using open-source geochemistry and porous flow modules of the MOOSE computational framework. For the passage of a single pore volume, chalcedony, nontronite-Mg, and kaolinite accumulations are estimated with minimal basalt dissolution. The preliminary simulation results are consistent with the abundant initial basalt amounts in the simulation and 2-day residence time for the passage of a pore volume. Future work includes validation of the reactive transport model with additional experimental results and parametric studies to help guide the design of a planned field-scale pilot.