中文摘要：

泥页岩地层井壁失稳的主要原因是泥页岩吸水后发生膨胀和掉块。针对这种情况提出了使用纳米二氧化硅封堵泥页岩纳米级孔喉、降低其渗透率从而减缓水分侵蚀的思路。在前期研究基础上，通过透射电镜分析、钻井液常规性能测试和扫描电镜分析等手段，评价了不同温度下纳米二氧化硅对钻井液滤失性的改善效果。结果表明：纳米二氧化硅可以有效地降低淡水基浆和膨润土基浆在升温过程中的失水量：室温下失水量降低率为56．25％，140℃时失水量降低率为78％，而对低固相基浆则效果一般；相对于纳米二氧化硅的质量浓度5％，其质量浓度为10％时可以使钻井液形成较为连续而致密的滤饼，封堵能力加强。由此可见，纳米二氧化硅可以有效改善淡水基浆和膨润土基浆的降滤失性能，且在温度升高过程中（室温～160℃）表现较好。

英文摘要：

The main reason causing clay shale formation wellbore instability is that the expansion and sloughing of clay shale after water absorption. The thought was proposed that silicon dioxide nano-particles was used to plug the nano-size pores and throats of shale to reduce the permeability of shale, resulting in decreasing and delaying water invasion into shale. On the basis of preliminary studies, the paper evaluated the improvement effect of three types of drilling mud with two brands of silica nano-particles at different tempera- ture, by means of transmission electron microscopy analysis, regular performance test of drilling fluid and scanning electron microscope analysis. Results show that silica nano-particles could effectively reduce the filtration of Fresh Water Mud （ FWM ） and Bentonite Mud （ BM ） with temperature increase. It could reduce the loss of water by 56.25% at room temperature and 78% at 140 ~C. It has little effect on Low Solid Mud （ LSM ） . Finally, to the drilling mud with the weight concentration of 10% had better plugging capacity than that with the weight concentration of 5% because of forming more continuous and tight mud cake. Based on the experiment results, FWM and BM＇s filtration properties could be improved using nano-particles with temperature increase （ from room temperature to 160 % ） .