It is generally recognized that the stick-slip motion of a polycrystalline diamond compact (PDC) bit is responsible for the low rate of penetration (ROP) and premature failure of the PDC bit when drilling in hard rock formations. To solve this problem, a torsional vibration damping tool was developed. A working principle model of the tool and a calculation model of the optimal spiral angle of the tool was established. The stability of the tool was analyzed, and the parameter range of spiral guideline thread stability was determined. The analysis revealed that the tool can automatically adjust the weight on the bit (WOB) and the rotary speed of the PDC bit through the spiral guide and the disc spring, which could suppress the torsional vibration of the PDC bit and convert part of the vibration load into cutting torque for rock breaking and thus to improve the rate of penetration (ROP). The optimal spiral angle of the tool is proportional to the axial stiffiless, bit diameter, and rock hardness of the drill string system and inversely proportional to the torsional stiffness of the drill string system and the reclining angle of the PDC bit. The stability of the tool is related to the spiral angle, length, and friction angle of the spiral guide. The tools were applied in test wells, and the results indicate that the torque fluctuations are significantly decreased and effectively extend the service life of the PDC bit. During the test process, the tool exhibits steady performance, the feasibility of the tool calculation model was verified. It is anticipated that the presented results will make such drilling a more feasible method for well services.

中文翻译：

---

PDC钻头扭振减振工具的研制及动力学分析

人们普遍认为，在硬岩层中钻孔时，多晶金刚石复合片 (PDC) 钻头的粘滑运动是导致 PDC 钻头的低钻速 (ROP) 和过早损坏的原因。为了解决这个问题，开发了一种扭转振动阻尼工具。建立了刀具工作原理模型和刀具最佳螺旋角计算模型。分析了刀具的稳定性，确定了螺旋导向螺纹稳定性的参数范围。分析表明，该工具可以通过螺旋导轨和碟形弹簧自动调节钻头上的重量（WOB）和PDC钻头的转速，可抑制PDC钻头的扭转振动，将部分振动载荷转化为用于破岩的切削扭矩，从而提高钻速（ROP）。工具的最佳螺旋角与钻柱系统的轴向刚度、钻头直径和岩石硬度成正比，与钻柱系统的扭转刚度和PDC钻头的后倾角成反比。刀具的稳定性与螺旋导轨的螺旋角、长度和摩擦角有关。该工具在试井中应用，结果表明扭矩波动显着降低，有效延长了PDC钻头的使用寿命。在试验过程中，工具表现出稳定的性能，验证了工具计算模型的可行性。