Reservoir wettability is very important to predict the structure and residual capture capacity, potential CO₂ leakage accidents and improve the risk assessment and sequestration safety during CO₂ geological sequestration. The wetting behavior of fluid on reservoir rock surface is actually an interface phenomenon caused by the interaction of different fluid molecules on rock surface. At present, it is difficult for laboratory experiments to observe the microscopic interface phenomena at the molecular scale under reservoir conditions, while molecular dynamics simulations can characterize the microscopic changes in wetting behavior and analyze the interaction between the fluid and the rock surface. In this study, molecular dynamics simulations are used to study the effects of different CO₂ densities and different salinities on the wetting behavior of formation water on the sandstone surface during CO₂ geological sequestration. The results show that both salinity and CO₂ density have significant effects on the wettability of quartz surfaces. However, the increase in salinity can only weaken the wettability, while the increase in CO₂ density can transform the wettability of the quartz surface. Both CO₂ molecules and H₂O molecules form two adsorption layers at 3.5 Å and 6.9 Å away from the quartz surface. CO₂ molecules will replace the positions originally occupied by water molecules on the quartz surface, reducing the contact area between water droplets and the quartz surface. The CO₂ density mainly affects the interface behavior between the components in the system, while the NaCl concentration mainly affects the interaction between H₂O molecules and ions in the system. The research results can further improve the understanding of the wettability of fluid on the pore surface of reservoir rocks during CO₂ geological sequestration.

储层润湿性对于预测结构和剩余捕获能力、潜在的CO ₂泄漏事故以及提高CO ₂地质封存过程中的风险评估和封存安全性非常重要。流体在储层岩石表面的润湿行为实际上是岩石表面不同流体分子相互作用引起的界面现象。目前，实验室实验很难观察到微观界面现象。储层条件下的分子尺度，而分子动力学模拟可以表征润湿行为的微观变化并分析流体与岩石表面之间的相互作用。本研究通过分子动力学模拟研究了不同CO _{2密度和不同矿化度对CO 2}地质封存过程中地层水在砂岩表面润湿行为的影响。结果表明，盐度和CO ₂密度对石英表面的润湿性都有显着影响。然而，盐度的增加只能削弱润湿性，而CO ₂密度的增加可以改变石英表面的润湿性。两者一氧化碳_{2 个}分子和 H ₂ O 分子在距离石英表面 3.5 Å 和 6.9 Å 处形成两个吸附层。CO ₂分子将取代石英表面原本由水分子占据的位置，减少水滴与石英表面的接触面积。CO ₂浓度主要影响体系中各组分之间的界面行为，而NaCl浓度主要影响体系中H ₂ O分子与离子的相互作用。_{该研究成果可进一步提高对CO 2}地质封存过程中储层岩石孔隙表面流体润湿性的认识。