甲酸钾钻井液体系在川南页岩气地区的应用

Application of potassium formate drilling fluid system in shale gas area in southern Sichuan

页岩气区别于常规天然气,以多种相态形式大量附存于富有机质的泥页岩及其夹层中,是一种清洁高效的非常规能源[1]。由于页岩地层岩性通常以泥页岩为主,岩性本身敏感性强,且微裂缝发育,页岩气井钻井施工过程中复杂问题频出。针对页岩气井施工过程中难以维持井眼完整性的难题,通过总结学习大量已完工井次防塌经验的基础上,优选了钻井液防塌封堵剂和有机盐抑制剂,从“系统级”方面进行了钻井液体系优化,构建了甲酸钾防塌钻井液并在川南页岩气区块多口井直井段中成功应用,有效抑制了该区域钻井施工井壁失稳等复杂情况的发生,明显的提升了机械钻速,缩短了钻井周期,带来了可观的经济效益。

Shale gas is different from conventional natural gas. It is a clean and efficient unconventional energy, which is largely attached to organic rich shale and its interlayer in a variety of phase forms[1]. Because the lithology of shale formation is usually dominated by shale, the lithology itself is highly sensitive and micro fractures are developed, complex problems occur frequently in the drilling and construction of shale gas wells. Aiming at the problem that it is difficult to maintain borehole integrity during shale gas well construction, based on summarizing and learning a large number of collapse prevention experience of completed wells, the drilling fluid anti collapse plugging agent and organic salt inhibitor are optimized.The drilling fluid system is optimized from the "system level".The potassium formate anti collapse drilling fluid is constructed and successfull y applied in the vertical well sections of multiple wells in southern Sichuan shale gas block.It effectively inhibits the occurrence of complex situations such as wellbore instability in drilling construction in this area, signifi-cantly improves the mechanical ROP, shortens the drilling cycle, and brings considerable economic benefits.