Numerical sensitivity analysis of CO2 mineralization trapping mechanisms in a deep saline aquifer

There is a growing interest in geo-sequestration of CO2 for its safe disposal given the emergency of global greenhouse gas emissions reduction. Depleted oil and gas fields and deep saline aquifers are the most promising CO2 storage locations. Deep saline aquifers have been regarded preferable due to their widespread and great storage capacity. However, there exists a notable research gap regarding the understanding of CO2 geochemical reactivity with in-situ minerals, specifically in deep saline aquifers. Hence, this study focuses on the mineralization trapping mechanisms of CO2 by simulating the sequestration of at least 48 million tons of CO2 over a five-year period in a saline aquifer. The effectiveness of CO2 mineralization trapping for the siliciclastic aquifer was analyzed and characterized in relation to injection period, pressure, temperature, and salinity. The ability of the aquifer to store significant amounts of injected CO2 for a duration of 1000 years was studied using a numerical simulator. Our study also examines geochemical-induced changes, such as pH and porosity, resulting from mineralization. The results reveal that longer injection periods enhance the efficiency of CO2 mineralization trapping, primarily due to the increased availability of CO2 in the reservoir. Moreover, our findings provide valuable insights into the optimal mineralization temperatures for the simulated minerals, determining their dissolution or precipitation tendencies. Notably, calcite and dolomite exhibit higher mineralization efficiency at medium and lower temperatures, while minerals like illite, kaolinite, K-feldspar, and quartz are more favorably reactive at higher temperatures. Although porosity and pH exhibited minimal variations, they were sufficient to indicate the dynamics of mineral reactivity and mineralization trapping efficiency. By addressing these research gaps and presenting our novel findings, this study significantly contributes to the understanding of CO2 storage in deep saline aquifers and offers valuable insights for optimizing CO2 mineralization processes.

Automated summary

This study investigates the mineralization trapping mechanisms of CO2 in deep saline aquifers through simulation, examining the effects of injection period, pressure, temperature, and salinity. The research reveals that longer injection periods enhance the efficiency of CO2 mineralization trapping, while different minerals have specific temperature preferences for mineralization. The study contributes to the understanding of CO2 storage in deep saline aquifers and provides insights for optimizing CO2 mineralization processes.