【摘要】 针对深部咸水层CO₂地质封存注入井附近干化结晶可能增大工程运行成本和近井区安全风险且盐结晶对CO₂-咸水两相流的影响机制不清的问题，通过室内CO₂岩心驱替试验研究了不同盐度咸水饱和岩心条件下CO₂的注入性变化规律。结果表明：无论咸水盐度高低，干化效应过程总会产生不均匀盐结晶，去离子水和低盐度咸水内干化效应过程提升了气体有效渗透率，但随着咸水盐度提高，岩心残余水饱和度、干化速率、盐结晶量均显著增加，且气体注入性降低明显；岩心驱替试验可表征为推动驱替、携带驱替和溶解驱替3个阶段，干化效应发生在携带驱替阶段和溶解驱替阶段，开始于孔隙毛细水形成之后；孔隙内盐结晶界面演化包括收缩结晶和结晶扩展两个过程，结晶对气体注入性的影响取决于岩心孔隙内溶液收缩与结晶扩张的竞争，咸水盐度越高，结晶扩展的优势越大，可能造成更严重的气体注入性损失。更多还原

【Abstract】 Salt crystallization near the injection well of deep saline aquifers for CO₂ geological storage may increase engineering operation costs and pose safety risks in the near-wellbore region, and the mechanisms by which salt crystallization affects CO₂-brine two-phase flow remain unclear. To address these issues, the variation patterns of CO₂ injectivity under different salinity conditions in brine-saturated cores were investigated through laboratory CO₂ core displacement experiments. Results demonstrate that non-uniform salt crystallization occurs during the drying process regardless of salinity. In deionized water and low-salinity brine, the drying effect enhances effective gas permeability. However, higher salinity significantly increases residual water saturation, drying rates, and salt accumulation, leading to a marked reduction in gas injectivity. The core displacement process is characterized by three stages, namely displacement, entrainment, and dissolution flooding, with drying occurring during the displacement and entrainment stages after pore capillary water forms. Furthermore, the pore-scale salt crystallization interface involves a shrinkage and expansion process. The influence of crystallization on gas injectivity depends on the competition between solution shrinkage and crystal expansion; higher salinity promotes crystal expansion, causing more severe gas injectivity loss.更多还原