双级双速钻井工具设计与现场试验

为了充分发挥PDC钻头高效破岩的技术优势，进一步提高其在低渗透地层的机械钻速，研究并设计了双级双速钻井工具。采用数值模拟方法建立了双级双速钻井时的井底岩石物理模型，分析了井底岩石应力分布状态及双级双速钻井的破岩和提速机理；介绍了双级双速钻井工具的常见结构，指出了其技术优势；基于已有研究成果，并结合现场实际需要，从排量、输出扭矩与转速、钻进工具长度等方面进行优化设计，设计出了适用于?215.9，?241.3和?311.1 mm井眼的双级双速钻井工具。设计的双级双速钻井工具在胜利油田3口井进行了现场试验，试验结果表明，双级双速钻井工具使用时钻压、泵压及工具性能稳定，机械钻速比邻井平均提高80.37%，总体效果显著。研究认为，设计的双级双速钻井工具综合性能好，在低渗透地层钻进时能够提高机械钻速，具有推广应用价值。  

The Design and Field Testing of Two-Stage and Two-Speed Drilling Tools

In order to fully exploit the technical advantages of PDC bit in rock breaking, and to further improve its ROP in low permeability formation drilling, a two-stage and two-speed drilling tool was studied and designed. A numerical simulation method was used to establish the bottom hole petrophysical model during the two-stage and two-speed drilling, stress field distribution and rock breaking/speed-up mechanisms of two-stage and two-speed drilling were analyzed. The common structure of two-stage and two-speed drilling tool and its technical advantages were presented. Based on the research results and field site requirements, the two-stage two-speed drilling tools for ?215.9, ?241.3 and ?311.1 mm diameter borehole were optimally designed considering flow rate, output torque and rotary speed, drilling tool length, etc.. The tool was tested in 3 wells of Shengli Oilfield and it showed that the WOB, pumping pressure and tool performance are stable, and the ROP is 80.37% higher than that of the offset wells with normal tools. The designed two-stage and two-speed drilling tool presents a good comprehensive performance and can be used to improve ROP in low permeability formation drilling with good application prospective.