Abstract: As the first horizontal well drilled in the deep ultra-thin reservoir in Zhongyuan Oilfield, well Wen92-p1 is the most difficult well drilled in recent years, due to the hard formation, deep depth, high pressure coefficient, long open hole section, thin reservoir and highly uncertainty of formation condition, etc.Multiple modifications were carried out on geology design during drilling, and the vertical depth was continuously adjusted to trace the reservoir, causing great difficulties on hole trajectory controlling.Regular borehole was achieved by applying the steerable BHA and MWD, and the use of polyol-positive colloid drilling fluid system ensured the downhole safety;high-efficient PDC bit was selected, and proper BHA and drilling parameters were optimized.The production ratewas 41.1t/d, which is 8 times of the offset well, with remarkable economic benefits achieved.