Well Chengtan-1 is the first ultra-deep well over 7000m in Tadong block of Daqing oilfield. Through analyzing the data of the adjacent wells and optimizing the wellbore structure, BHA and drilling fluid system, a bit series suitable for Gucheng block was established. Using China-made hydraulic rotary tools, the difficult drilling speed improvement in “black quilt” formation of Tadong, where a φ241.3mm hole was located, was solved and the drilling cycle was shortened by higher ROP.