Implications and problems of research on salt precipitation during CO₂ injection into saline sandstone: a comprehensive review

Carbon capture, utilization and sequestration (CCUS) technology is considered an effective technology for reducing anthropogenic carbon dioxide emissions into the atmosphere. Saline aquifers are the most promising places for CO₂ storage. However, field practice has demonstrated that salt precipitation near wellbores could lower reservoir permeability and result in a loss of CO₂ injectivity. This paper reviews the research progress on salt precipitation during CO₂ injection into saline aquifers. First, the mechanism of salt precipitation is studied in terms of the CO₂ injection stage division and salt precipitation occurrence characteristics. Second, the current technical approaches for salt precipitation research are examined, encompassing numerical simulations, core tests and analytical solutions, and the accomplishments and advancements of these three methods are analyzed. The factors that govern salt precipitation, such as reservoir heterogeneity, salinity, injection rate, temperature, and wettability, are also analyzed. Eventually, the current state of CO₂ storage in saline sandstone is presented, and a number of problems in salt precipitation research are identified.