Expanding Carbon Sequestration for Small-to-Medium Emitters: Pros and Cons of Coupling Simultaneous scCO2-Brine Aquifer Injection (SAI) or Water Alternating Gas (WAG) with Saltwater Disposal Wells (SWD)

Abstract As the urgency to combat climate change intensifies, developing innovative and efficient carbon sequestration strategies to capture and store carbon dioxide (CO2) from industrial sources has become a critical priority. This paper reviews the simultaneous scCO2-brine aquifer injection (SAI) and water alternating gas (WAG) methods for geologic carbon sequestration and proposes a novel integration with saltwater disposal wells (SWDs). Small-to-medium emitters, defined as facilities emitting between 10,000 and 100,000 metric tons of CO2 annually, stand to benefit significantly from this approach, which leverages pre-existing infrastructure to reduce costs while enhancing storage efficiency. The SAI-WAG method optimizes injection practices by balancing the flood front, accelerating mineral carbonation, and improving sequestration efficiency. Coupling SAI-WAG with SWDs may offer economic advantages by reducing the need for additional wells in geological CO2 storage. However, challenges such as high salinity, mechanical stability, overpressure, and injectivity loss must be addressed to ensure feasibility. To strengthen the cause for this method, we recommend conducting quantitative analyses to evaluate its potential for reducing CO2 emissions and improving storage capacity. This study provides critical insights into the feasibility and viability of the SAI-WAG method, offering a promising pathway for advancing CCS technologies. Future research will explore the long-term stability and effectiveness of this approach to support its widespread adoption.