Geoelectrical Evaluation of CO₂ Storage in Carbonate Aquifers Using Carbonated Water Injection

The rising levels of carbon dioxide (CO2) in the atmosphere and its role in global climate change have necessitated the development of effective carbon storage strategies. Geological storage of CO2 in saline aquifers is a viable method to reduce CO2 emissions due to its extensive size. However, mineral trapping, where CO2 interacts with aquifer minerals or cations in the brine and converts the injected CO2 into stable carbonates, is one of the most secure carbon storage mechanisms, contributing to the long-term retention of CO2. Nevertheless, the dynamic processes governing mineral trapping, especially under different temperature conditions, remain insufficiently understood. Therefore, this study employs real-time electrical resistivity measurements to examine the geochemical interactions and their impact following carbonated water injection. Additionally, the study assesses changes in pore structure, pore connectivity, mineral dissolution, and precipitation behavior through microcomputed tomography scans, effluent fluid analysis, and nuclear magnetic resonance. Results revealed a notable reduction in electrical resistivity after carbonated water injection, attributed to increased ionic strength, highlighting the effectiveness of resistivity logging for real-time monitoring of CO2 injection. Furthermore, temperature was found to significantly influence wormhole formation, a key outcome of rock dissolution. While dissolution was less evident at 30 °C, a temperature of 50 °C promoted widespread wormhole formation due to enhanced mineral dissolution. However, at 70 °C, mineral dissolution was limited owing to decreased CO2 solubility at higher temperatures. These findings suggest that 50 °C provides the optimal conditions for long-term CO2 storage via carbonated water injection in carbonate aquifers, balancing pore structure enhancement with stable mineral trapping.