沁平12-11-3H煤层气六分支水平井绒囊钻井液技术

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4 189.49 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。

Fuzzy-ball drilling fluid technology in CBM of multilateral horizontal well Qinping 12-11-3H with six branch holes

The No. 3 coalbed in Qinshui Basin is high rank coal seam, the drilling of coalbed methane encountered rockfall, collapsing, 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 fluid 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 fluid additives: core-forming agent, film-forming agent, layer-forming agent and fuzzy-forming agent were added to adjust the drilling fluid properties. The drilling fluid 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 fluid 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 fluid, 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 fluid.