常压页岩气用“四低四高”油基钻井液技术研究与应用

常压页岩气储层页理层理、微裂隙发育,水平井钻井井壁稳定难度大、钻井液漏失风险高,商业开发降本提效需求迫切。为此文章研发了一套黏度低、滤失量低、加量低、油水比低和破乳电压高、切力高、动塑比高、稳定性高的"四低四高"油基钻井液体系,室内结果表明其整体性能指标达到或优于国外同类技术水平。该油基钻井液在武隆和梨树等常压气区块多口井成功应用,现场油水比可降至60/40,较以往技术单井平均减少基础油用量约50t,取得了良好的应用效果和经济效益。本研究对于常压页岩气水平井钻井液成本控制具有重要意义和参考价值。

Normal pressure shale gas reservoir has plenty of stratifications and microfractures, so it was a great challenge fordrilling a horizontal well to maintain borehole wall stability, control drilling fluid loss and reduce commercial development cost.Therefore, an oil-base drilling fluid formation was researched, which had the characters of low viscosity, low filtration loss, low dosage, low oil-water ratio, high breaking of emulsion voltage, high shear force, high dynamic plastic ratio, high stability. The experimental results display that the performance of this formation is up to or better than that of similar foreign technologies. This oil-based drilling fluid has been successfully applied in many wells in Wulong and Lishunormal pressuregas blocks. The oil-water ratio waskeptat 60/40, which saved about 50 tons base oil every well and reduced the cost of drilling fluid. This study has great significance and reference value for the cost control of drilling fluid in normal pressure shale gas horizontal wells.