Boundary conditions of stick-slip vibrations and motion equations of bit were analyzed with establishing a theory analytical model with torsion pendulum, vibration mechanism and influence factors and movements of bit were researched..Results show that circulation accumulation of the cutting bit and friction between the string and the wall were primary causes of the stick-slip vibration,unstable forces of bit were primary cause of the PDC bits failure. Vibrations relate to drilling parameters,formation characteristics,drilling tools and properties of drilling fluid. Vibrations could be mitigated by changing the drilling parameters or adding a hydraulic pressure device or torsion impact.%建立扭转摆理论分析模型及钻头的运动方程,分析钻头粘滑振动的边界条件,研究钻头的运动形式及粘滑振动机理与影响因素.结果表明:钻头切削岩石时主动扭矩的循环积聚与释放以及钻柱与井壁的摩擦是引起粘滑振动的主要原因；钻头不稳定的受力是造成PDC钻头失效的主要原因.粘滑振动与钻井参数、地层特性、钻具参数及钻井液性能等有关,调整钻井参数,或使用水力加压器、扭转冲击器等工具可以减少振动.
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