Yang Liu, Ge Jijiang, Wu Hao, Li Xiaqing, Li Jianda, Zhang Guicai
School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, Shandong 266580, China.
Sinopec Shengli Oilfield Petroleum Engineering Technology Research Institute, Dongying, Shandong 257091, China.
ACS Omega. 2024 Nov 26;9(49):48427-48437. doi: 10.1021/acsomega.4c06834. eCollection 2024 Dec 10.
Pickering emulsions stabilized by surfactant-modified SiO nanoparticles demonstrate good stability against droplet coalescence, showing application potential for enhanced oil recovery in high-temperature and high-salinity environments. Adjusting the adsorption ratio of surfactant on the nanoparticles significantly affects the wettability of nanoparticles and therefore regulates the microstructure and properties of Pickering emulsions. In this study, a saturated monolayer adsorption occurs at a surfactant-to-nanoparticles ratio of 0.1:1.0%, where an optimal hydrophilic-hydrophobic balance is achieved. However, below or above this ratio, the SiO nanoparticles become more hydrophilic with the decreasing or increasing surfactant concentration. Pickering emulsions stabilized by the intermediate wet nanoparticles exhibit the best stability and highest viscosity. Laser confocal scanning microscopy and cryo-scanning electron microscopy reveal that the SiO nanoparticles can form a bridge-structure network among the droplets of these emulsions. Microfluidic experiments and sand pack experiments show that Pickering emulsions provide greater permeation resistance than conventional emulsions stabilized solely by surfactant solely. In addition, microscopic experiments show that Pickering emulsions enhance oil recovery by 20% after second waterflooding, compared to a 12% recovery rate with conventional emulsions. It is found that the Pickering emulsions with bridge-structures may be accumulated in and plug channels much larger than their droplets, which results in higher properties of conformance control.
由表面活性剂改性的SiO纳米颗粒稳定的Pickering乳液对液滴聚结表现出良好的稳定性，在高温高盐环境下的提高采收率方面显示出应用潜力。调节表面活性剂在纳米颗粒上的吸附比例会显著影响纳米颗粒的润湿性，从而调节Pickering乳液的微观结构和性能。在本研究中，当表面活性剂与纳米颗粒的比例为0.1:1.0%时会发生饱和单层吸附，此时实现了最佳的亲水-疏水平衡。然而，低于或高于该比例时，随着表面活性剂浓度的降低或增加，SiO纳米颗粒变得更亲水。由中等润湿性纳米颗粒稳定的Pickering乳液表现出最佳的稳定性和最高的粘度。激光共聚焦扫描显微镜和低温扫描电子显微镜显示，SiO纳米颗粒可以在这些乳液的液滴之间形成桥状结构网络。微流控实验和填砂实验表明，Pickering乳液比仅由表面活性剂稳定的传统乳液具有更高的抗渗性。此外，微观实验表明，二次水驱后，Pickering乳液的采收率提高了20%，而传统乳液的采收率为12%。研究发现，具有桥状结构的Pickering乳液可能会在比其液滴大得多的孔道中聚集并堵塞，从而导致更高的调剖性能。
