页岩气钻探冲洗液体系的研究与应用

Research and Application of the Flushing Fluid System for Shale Gas Drilling

中国页岩气资源开发潜力巨大,近年来页岩气勘探开发力度不断加大,对钻探工艺和技术的要求不断提高。页岩气地层岩性主要为泥岩、砂岩、页岩、碳质板岩、灰岩,该类地层胶结性差、破碎、井壁强度低,钻进中易出现孔壁失稳,发生坍塌、卡钻、埋钻等孔内事故,需要研制具有强抑制性、低成本、绿色环保的冲洗液体系来保证施工安全。本文通过对页岩气井壁稳定机理的探究,优选出一种适用于页岩地层双聚防塌和成膜防塌低固相冲洗液体系,该体系由抑制剂、防塌剂、降失水剂、润滑剂、封堵剂、流型调节剂等处理剂组成,具有良好的抑制性和胶结性。现场应用取得了良好的效果,保证了项目的顺利施工。

Shale gas resource potential is tremendous huge in China. In recent years, the requirements of the drilling process and technology are continue to increase along with the efforts of exploration and development of shale gas and un- conventional energy sources. Shale gas formation lithology is mainly mudstone, sandstone, shale, carbonaceous slate and limestone. Because of poor formation cementation, broken and low wall strength, hole wall instability, collapse and sticking or braying accidents were liable to happen in drilling process, the flushing fluid system with strong inhibitory, good compat- ibility, low cost, green environmental protection drilling fluids is needed in the drilling engineering construction. Based on the research on the mechanism of shale borehole wall stability, a low solid phase flushing fluid system with double polyethy- lene anti-sloughing and film forming anti-sloughing is optimized, which is suitable for shale formation. The system is consis- ted of inhibitors, anti-sloughing agent, agents, fluid loss additives, lubricants, blocking agents and flow pattern regulators with good inhibition and cementation. Good construction effects have been achieved in a number of field applications.