Abstract: The high temperature stability and wellbore cleaning problems of oil⁃based drilling fluid have to be solved when it is used to drill extended reach wells in the KQT gas field located in the East China Sea. For this reason, the key additives of oil⁃based drilling fluid including the emulsifier, wetting agent, rheology modifier and organic clay were selected using the interfacial tension test, emulsifying efficiency test, microscope observation, emulsion viscoelasticity and rheological property tests. After that, the oil⁃based drilling fluid for extended reach wells was developed, and the comprehensive properties were tested. The results show that the drilling fluid has good stability after hot rolled at 180 °C. The selected rheology modifier can enhance the structure strength of oil⁃based drilling fluid, and effectively increase the gel strength and low shear rate viscosity, thus increasing the wellbore cleaning effect. Meanwhile, it has good filtration property and contamination resistance property. This drilling fluid has been used in 4 wells in the KQT gas field, and good field application results are obtained.

Key words: Oil?based drilling fluid, Extended reach well, Wellbore cleaning, Rheology modifier, Filed application

摘要： 我国东海KQT气田大位移井钻进过程中油基钻井液存在高温稳定性及井眼清洗技术问题。为此，通过界面张力测试、乳化效率测试、显微镜观察及乳状液黏弹性和流变性测试等实验方法，优选了乳化剂、润湿剂、流型调节剂及有机土等关键处理剂，构建了大位移井用油基钻井液体系，并对其进行了综合性能评价。结果表明，该钻井液在180 ℃热滚后仍具有良好的稳定性；优选的流型调节剂可增强钻井液的结构强度，有效提高切力和低剪切速率黏度，保证井眼清洗效果；同时具有良好的滤失性及抗污染性能等。在KQT气田的4口井中进行了现场试验，取得了良好的应用效果。

关键词: 油基钻井液, 大位移井, 井眼清洗, 流型调节剂, 现场试验