脉动式扭转冲击钻井工具工作特性分析与测试

为抑制PDC钻头钻进硬地层时的粘滑振动，设计了一种可以为PDC钻头提供周向冲击载荷的脉动式扭转冲击钻井工具，并在介绍其结构设计和分析其工作原理的基础上，建立了计算其周向扭矩、直井工况下冲击功的数学模型，通过算例分析了其工作特性。分析结果表明:脉动式扭转冲击钻井工具的周向扭矩随排量增大而增大，随节流喷嘴直径增大而减小；在直井中的冲击功随钻柱扭矩和扭转角度增加而增大，随钻压增大而减小。脉动式扭转冲击钻井工具样机性能室内测试结果表明，该钻井工具能实现高频扭转冲击，且其工作频率、周向腔体压差和周向扭矩均随排量增大而增大。研究和测试结果表明，脉动式扭转冲击钻井工具的结构设计合理，能够为PDC钻头提供周期性扭转冲击载荷，抑制PDC钻头的粘滑振动。 

Analysis and Testing of the Working Characteristics of a Pulsating Torsional Impact Drilling Tool

A pulsating torsional impact drilling tool was designed to provide a polycrystalline diamond compact (PDC) bit with a circumferential impact load to suppress the stick-slip vibration of the bit when it drills into hard formations. First, the structural design of the drilling tool was introduced, and its working principle was analyzed. Then, on this basis, mathematical models were established for calculating its impact energy in vertical wells and circumferential torque. Finally, the working characteristics of the drilling tool were analyzed. The analysis results showed that the circumferential torque of the pulsating torsional impact drilling tool increased with the increase in flow rate and decreased with the increase in the diameter of the throttle nozzle. Its impact energy in vertical wells became higher with the increase in the torque and rotation of the drill string; however it declined as the weight on bit (WOB) increased. The performance of the pulsating torsional impact drilling tool prototype was explored through laboratory tests. The test results were positive and indicated that the drilling tool could achieve high-frequency torsional impact, and its operating frequency, circumferential cavity pressure difference, and circumferential torque were all enhanced with the increase in flow rate. The research and test results demonstrate that the pulsating torsional impact drilling tool has an acceptable structural design, which can provide periodic torsional impact loads for PDC bits and suppress the stick-slip vibration.