The No. 3 coalbed in Qinshui Basin is high rank coal seam, the drilling of coalbed methane encountered rockfall, col-lapsing, lost circulation, sticking and the rate of successful drilling was very low. The third spudding of Qinping 12-11-3H Well was a multi-lateral horizontal well consisting of two main branches and six branches;the fuzzy-ball drilling lfuid was applied in 13 days and drilled 4 189.49 m. According to the different downhole situations and solid-control equipment, four kinds of fuzzy-ball drilling lfuid additives:core-forming agent, iflm-forming agent, layer-forming agent and fuzzy-forming agent were added to adjust the drilling lfuid properties. The drilling lfuid density was 0.96-1.08 g/cm3, plastic viscosity was 7-17 mPa·s, dynamic shear force was 4.0-10.22 Pa, and coalbed methane encountering rate was 95%. The drilling lfuid met the geological requirements and the average ROP was 12.65 m/h, which had improved by 11.55%when compared with adjacent wells. This drilling tested the capacities of the fuzzy-ball drilling lfuid, including the accommodating capacity of high percentage of solid phase , plugging capacity in leaking formations, processing capability for well collapsing and pipe sticking, and the maintaining performance capacity during gas invasion. It is suggested that auxiliary solid-control equipment is needed to further improve the performance of the drilling lfuid.%沁水盆地3#高阶煤层，煤层气钻井过程中掉块、垮塌、漏失、卡钻，成功率很低。沁平12-11-3H井三开是由2个主支、6个分支组成的多分支水平井，使用绒囊钻井液13 d完成进尺4189.49 m。根据不同井下情况、固控设备情况，加入成核剂、成膜剂、囊层剂和绒毛剂等4种绒囊钻井液主处理剂，调整钻井液性能：密度0.96~1.08 g/cm3，塑性黏度7~17 mPa·s，动切力4.0~10.22 Pa，煤层钻遇率达95%，完成地质要求且平均机械钻速12.65 m/h，较邻井提高11.55%。全井考验了绒囊钻井液高固相容纳能力、漏失地层封堵能力、井塌卡钻处理能力、气侵维持性能能力。建议加强固控设备配套，进一步提高钻井液性能。
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