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文章分析研究了大位移井钻井过程中对钻具破坏很强的一种扭转振动：“粘滞—滑动”,这种振动在大位移井钻井过程中发生的概率比较大,表现为或停或转的状态,转动的瞬间钻头以很大的速度冲出,引起钻头与地层、钻柱与井壁强烈碰撞,因此引起钻具失效。通过建立大位移井钻柱的等效扭转摆模型,分析了在钻头与地层扭矩及钻柱与井壁间摩阻扭矩作用下钻柱的动态行为,给出了钻柱所受摩阻力与钻柱动态位移之间的函数关系。分析了钻柱“粘滞—滑动”振动所遵循的物理规律,获得了大位移井“粘滞—滑动”共振频率的分布。结果表明：大位移井的“粘滞—滑动”现象表现为低频反应。根据“粘滞—滑动”共振所满足的条件,通过调整钻井参数可以避免“粘滞—滑动”现象的发生;扭转负反馈对“粘滞—滑动”现象有一定的阻碍作用。该问题的分析结果具有较高的理论价值和实际意义,对大位移井钻进中如何减少钻具失效问题提供力学依据。

Research on the "Stricking-slipping" Law of Drilling String in Extended-reach Well

A torsional vibration--" sticking-shp-ping",which is very destructive to drill string in the process of drilling extended-reach well, is studied in the paper. The probability of causing the vibration in drilling this kind of well is relatively great. This vibration was expressed as the state of either stopping or rotating and the bit dashed out with very high velocity at the moment when it rotated, thus causing a strong impact between bit and formation and between drill string and borehole wall,and causing drill tool fatigue. Through setting up the equivalent torsion swing model of the drill string of extended-reach well,the dynamic behavior of drill string by the actions of the torque moment between bit and formation and the fractional torque moment between drill string and borehole wall was analyzed; the functional relation between the fractional resistance forced upon drill string and the dynamic displacement of drill string was put forward; and the resonat frequency distribution of the "sticking-slipping" in extended-reach well was obtained on the basis of analyzing the physical law followed by the "sticking-slipping"vibration of drill string. Results indicated that the "sticking-slipping" vibration of extended-reach well expressed as a low frequency phenomenon; and according to the conditions satisfied by " sticking-slipping" resonance, its occurrence might be avoided by adjusting drilling parameters; and the torsional nagtive feedback was of a certain obstruction effect on the"sticking-slipping"phenomenon. The research achievements of such a problem are of high theoretic value and practical sense, thus providing a mechanical basis for how to reduce drill string fatigue in drilling the extended-reach well.