Abstract: Xinye HF-2 well is the second horizontal shale gas exploratory well in the western Sichuan state. During its the fourth ?152.4 slim-hole drilling process, the pump showed higher pressure and lower displacement, and the orientator could not work normally. By using the drilling fluid hydraulics simulation software and ensuring the stable specific-gravity of oil-based drilling fluid, we combined the optimization of oil-based drilling fluid performance with the replacement of drilling tools to effectively reduce the pump pressure, increase the displacement volume, and keep the orientator at normal operation. In Xinye HF-2 well, the drilling of 821 m horizontal section finished with 2.15 g/cm3 oil-based drilling fluid. The practice offers useful references to operations in similar wells.