Analysis of Injectivity for CO₂ Sequestration in Saline Aquifers in the Yulin-Shenmu Region

The Yulin-Shenmu region, located in the northeastern Ordos Basin, boasts abundant carbon sources and a stable geological structure, making it an advantageous site for CO₂ sequestration in saline aquifers. This study focuses on the Zhi 3 Member of the Zhifang Formation and the Shiqianfeng Formation, conducting CO₂-water-rock interaction experiments and CO2 displacement tests to analyze the CO₂ injectivity potential of saline aquifers. The CO₂-water-rock interaction experiments reveal that upon CO₂ injection, silicate minerals such as clay minerals and feldspars undergo varying degrees of dissolution, accompanied by the precipitation of new minerals like calcite and halite. The CO₂ displacement tests indicate an increase in sandstone porosity after CO₂ injection, suggesting that the initial mineral dissolution effects outweigh those of mineral precipitation, effectively enhancing the injectivity of the reservoir. Based on CO₂ saturation calculations, the Shiqianfeng Formation exhibits good sequestration potential and is identified as the optimal target formation for subsequent CO₂ sequestration projects in saline aquifers.