A comprehensive review of remediation strategies for mitigating salt precipitation and enhancing CO injectivity during CO injection into saline aquifers.

Geological CO sequestration is a proven method for mitigating climate change by reducing atmospheric CO levels. However, CO injection often induces salt precipitation, leading to decreased formation permeability, which in turn limits CO injectivity and storage capacity. Conventional approaches, such as freshwater and low-salinity water injection, have been employed to mitigate salt precipitation. Despite their widespread use, these methods provide only temporary improvement and can be ineffective in some scenarios, resulting in long-term issues such as salt recrystallization and clay swelling. Given the complexity and significance of this issue, a comprehensive review of salt precipitation mechanisms and remediation techniques is essential. This paper critically examines the processes of salt precipitation during CO injection in saline aquifers and evaluates various remediation techniques aimed at improving CO injectivity. The paper reviews the influence of CO flow dynamics, geochemical reactions, and fluid properties on salt precipitation and pore throat accumulation, assessing the efficacy and limitations of existing mitigation methods. Additionally, the paper explores alternative techniques with potential for long-term CO sequestration, analyzing their advantages and drawbacks. Based on insights from the reviewed sources, the paper recommends exploring alternative treatment measures and the integration of hybrid solutions to enhance CO injectivity. The findings presented serve as a valuable reference for advancing research and practice in this critical area, offering a deeper understanding of the challenges and potential solutions for effective CO sequestration in saline aquifers.