Wang Yanling, Li Yongfei, Wang Qian, Li Qiang, Zhang Yue, Yuan Lin
College of Petroleum Engineering, China University of Petroleum (East China) Qingdao 266580 Shandong P. R. China
College of Chemical Engineering, China University of Petroleum (East China) Qingdao 266580 Shandong P. R. China.
RSC Adv. 2018 Feb 20;8(15):7924-7931. doi: 10.1039/c7ra10742k. eCollection 2018 Feb 19.
The wettability of a rock's surface is a vital factor for gas flow and fracturing fluid backflow. As a result of this, novel and effective gas wetting alteration agents are required. In this work, a gas-wetting alteration agent, ,-bis(perfluorooctyl)imine acetate sodium, was synthesized and characterized by different methods. The wettability of a rock's surface was evaluated by contact angle and imbibition measurements, the Owens two-liquid method and glass capillary tube rise testing. The results showed that after treatment with 0.5 wt% ,-bis(perfluorooctyl)imine acetate sodium the contact angles of water and -hexadecane on the surface of the rock increased from 36° and 0° to 140° and 119°, respectively. The surface free energy rapidly reduced from primeval 72 mN m to 3.4 mN m after treatment with 0.3 wt% ,-bis(perfluorooctyl)imine acetate sodium. These values agreed with the imbibition measurements and the results of the glass capillary tube rise testing. Moreover, analysis by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) showed that the roughness of the rock surface significantly increased. The above results fully proved that the wettability of the rock surface is altered from its original water-wetting or oil-wetting to gas-wetting. Furthermore, thermal analysis demonstrated that the gas-wetting alteration agent has good thermal stability, which indicates its great potential to be used as a gas-wetting alteration agent for unconventional gas reservoirs under high temperature conditions.
岩石表面的润湿性是气体流动和压裂液回流的一个关键因素。因此，需要新型且有效的气体润湿性改变剂。在这项工作中，合成了一种气体润湿性改变剂双（全氟辛基）亚胺乙酸钠，并采用不同方法对其进行了表征。通过接触角和自吸测量、欧文斯双液法以及玻璃毛细管上升测试对岩石表面的润湿性进行了评估。结果表明，用0.5 wt%的双（全氟辛基）亚胺乙酸钠处理后，岩石表面水和正十六烷的接触角分别从36°和0°增加到140°和119°。用0.3 wt%的双（全氟辛基）亚胺乙酸钠处理后，表面自由能从原始的72 mN/m迅速降至3.4 mN/m。这些数值与自吸测量结果以及玻璃毛细管上升测试结果相符。此外，扫描电子显微镜（SEM）和能谱（EDS）分析表明，岩石表面的粗糙度显著增加。上述结果充分证明，岩石表面的润湿性从原来的水湿性或油湿性转变为气湿性。此外，热分析表明该气体润湿性改变剂具有良好的热稳定性，这表明其在高温条件下作为非常规气藏气体润湿性改变剂具有巨大潜力。
