To improve the efficiency of coal seam water injection, the influence of nanofluids on coal surface wettability was studied based on the nano drag reduction and injection enhancement technology in the field of tertiary oil recovery. The composition optimization and performance evaluation of nanofluids with nano-silica and sodium lauryl sulfate as the main components were carried out, and the effects of the nanofluid with the optimal ratio on coal wettability were studied through spontaneous upward imbibition experiments. The results show that the composite nanofluid has a lower surface tension, and the lowest value of the interfacial tension is 15.79 mN/m. Therefore, the composite nanofluid can enhance the wettability of coal. However, its effects on coal samples with different metamorphic degrees is different, that is, low rank coal is the largest, middle rank coal is the second, and high rank coal is the least. In addition, a functional relationship between time and imbibition height is found for pulverized coal with different particle sizes. When the particle size of pulverized coal is 60–80 mesh, the wettability of nanofluid to coal is best. The findings in this paper provide a new perspective for improving the water injection efficiency for coal seams with low permeability.

为提高煤层注水效率，在三次采油领域基于纳米减阻增注技术研究了纳米流体对煤表面润湿性的影响。以纳米二氧化硅和十二烷基硫酸钠为主要成分的纳米流体进行了组成优化和性能评价，通过自发向上吸吸实验研究了最佳配比的纳米流体对煤润湿性的影响。结果表明，复合纳米流体具有较低的表面张力，界面张力最低值为15.79 mN/m。因此，复合纳米流体可以增强煤的润湿性。但其对不同变质程度煤样的影响是不同的，即 低阶煤最大，中阶煤次之，高阶煤最少。此外，对于不同粒度的煤粉，时间和吸胀高度之间存在函数关系。当煤粉粒度为60～80目时，纳米流体对煤的润湿性最好。本文的研究结果为提高低渗透煤层注水效率提供了新的视角。