Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
Environ Sci Technol. 2012 Apr 3;46(7):4228-35. doi: 10.1021/es204096w. Epub 2012 Mar 21.
Wettability of reservoir minerals and rocks is a critical factor controlling CO(2) mobility, residual trapping, and safe-storage in geologic carbon sequestration, and currently is the factor imparting the greatest uncertainty in predicting capillary behavior in porous media. Very little information on wettability in supercritical CO(2) (scCO(2))-mineral-brine systems is available. We studied pore-scale wettability and wettability alteration in scCO(2)-silica-brine systems using engineered micromodels (transparent pore networks), at 8.5 MPa and 45 °C, over a wide range of NaCl concentrations up to 5.0 M. Dewetting of silica surfaces upon reactions with scCO(2) was observed through water film thinning, water droplet formation, and contact angle increases within single pores. The brine contact angles increased from initial values near 0° up to 80° with larger increases under higher ionic strength conditions. Given the abundance of silica surfaces in reservoirs and caprocks, these results indicate that CO(2) induced dewetting may have important consequences on CO(2) sequestration including reducing capillary entry pressure, and altering quantities of CO(2) residual trapping, relative permeability, and caprock integrity.
储层矿物和岩石的润湿性是控制 CO2 流动性、残余捕获和地质封存安全性的关键因素，目前也是预测多孔介质中毛管行为时赋予最大不确定性的因素。关于超临界 CO2（scCO2）-矿物-盐水体系中润湿性的信息非常有限。我们使用工程化的微模型（透明孔隙网络），在 8.5 MPa 和 45°C 的条件下，研究了 NaCl 浓度高达 5.0 M 的范围内，scCO2-二氧化硅-盐水体系中的孔隙尺度润湿性和润湿性变化。通过水膜变薄、液滴形成以及单孔内接触角增大，观察到二氧化硅表面与 scCO2 反应时的去湿现象。盐水接触角从初始值接近 0°增加到 80°，在更高离子强度条件下增加更大。鉴于储层和盖层中存在大量的二氧化硅表面，这些结果表明 CO2 诱导的去湿可能对 CO2 封存产生重要影响，包括降低毛管进入压力，并改变 CO2 残余捕获量、相对渗透率和盖层完整性。
