川滇页岩气水平井水基钻井液技术

为解决水基钻井液钻页岩气水平井过程中出现坍塌等井壁失稳问题，以多碳醇、磺化沥青钾盐为核心处理剂，研究了一套针对川滇页岩气地层的新型水基钻井液。通过膨胀率、回收率、力学特性分析、封堵、抗污染等实验，研究了新型水基钻井液基本性能。结果表明，新型水基钻井液显著抑制云南龙马溪组、四川龙马溪组及五峰组页岩水化膨胀与分散，页岩膨胀率分别为1.23%、0.95%和0.98%，回收率分别为98.94%、99.13%和99.05%，其抑制页岩水化膨胀分散性能与油基钻井液相近；与常规水基钻井液相比，页岩抗压强度降低程度大幅减小，能有效减缓页岩抗压强度降低，对页岩裂缝具有较强的封堵性；抗盐（5% NaCl）、膨润土（5%）、岩屑（20%钻屑）污染能力强，具有良好的稳定井壁效果。 

Water Base Drilling Fluid Technology for Horizontal Shale Gas Drilling in Sichuan and Yunnan

Borehole wall instability has been a problem frequently encountered in horizontal shale gas drilling with water base drilling fluids. A new type of water base drilling fluid has been developed for use in shale gas drilling in Sichuan and Yunnan provinces. Higher alcohols and potassium salt of sulfonated asphalt were the main additives used in formulating the drilling fluid. The basic performances of the new drilling fluid were studied through laboratory experiments such as swelling test, hot rolling test, mechanical characteristics analysis, plugging test and contamination test. It was shown that the rates of swelling of the Longmaxi formation in Yunnan, Longmaxi formation and Wufeng formation in Sichuan were reduced to 1.23%, 0.95% and 0.98%, respectively, and the rates of shale cuttings recovery were 98.94%, 99.13% and 99.05%, respectively, indicating that the new drilling fluid had strong inhibitive capacity similar to that of oil base drilling fluids in inhibiting the shales drilled. Compared with conventional water base drilling fluids, the decreasing amplitude of the compressive strength of shales in contact with water base drilling fluids was greatly reduced. The new drilling fluid can plug shale fractures efficiently. Other advantages of the new drilling fluid included salt tolerance (5% NaCl), bentonite contamination tolerance (5%), drilled cutting contamination (20%).