超深井钻柱粘滑振动特征的测量与分析

粘滑振动是引起钻具失效、影响钻井时效的复杂振动形式，国内外学者对其产生机理进行了大量研究，但至今没有定论。采用ESM钻柱振动测量工具测量了某超深井井下钻柱的三轴加速度，通过分析三轴加速度的特征，研究了井下钻柱的粘滑振动特征。结果表明:实测井段发生了大量的粘滑振动，粘滑振动频率约为0.11 Hz，粘滑振动周期约为9.0 s，粘滞时长达4.0 s，滑脱阶段井下钻柱转速最大达330.0 r/min，约为地面转速的2.75倍；粘滑振动与地面测量扭矩波动具有很好的对应关系，说明可以通过地面测量扭矩特征初步判断井下钻柱是否产生粘滑振动。频域分析结果表明，当发生滑脱运动时，径向加速度的频谱中粘滑振动频率对应的能量幅值最大，同时还包含横向共振频率和与井壁接触产生的外激励频率等，但轴向振动的频谱中粘滑振动频率对应的能量幅值较小，表明钻柱粘滑振动过程中扭转振动最为突出，并存在强烈的横向振动和较弱的轴向振动。研究结果对描述粘滑振动的特征、判断超深井钻井过程是否发生粘滑振动和及时采取消除粘滑振动技术措施具有指导作用。 

Measurement and Analysis of Stick-Slip Characteristics of Drill String in Ultra-Deep Wells

Complicated stick-slip vibration might induce drilling tool failure and negatively impact drilling efficiency. Much research has been conducted on the mechanisms that cause the generation of such a vibration but they have not been able to arrive at a confirmed conclusion. In this paper, we present a study in which we used ESM drill string vibration measuring devices and tri-axial accelerations of a downhole drill string in an ultra-deep well.Through the analysis of tri-axial acceleration, the stick-slip vibration features of the drill string were reviewed. Research results showed that massive stick-slip vibration occurred in the concerned interval with a stick-slip frequency of 0.11 Hz, period of 9.0 s and a total stick time up to 4.0 s. During the slip stage, the maximum rotation speed of the downhole drill strings reached 330.0 r/min, approximately 2.75 times higher than that on the ground surface; Generally speaking, the stick-slip vibration was in accordance with fluctuations in surface torque. In other words, features of surface torque might be used for preliminary determination of stick-slip vibration of drill string in the borehole. Analysis of frequency show that stick-slip frequencies of radial acceleration were in accordance with the highest amplitude in energy during stick-slip. There were also horizontal resonance frequency and external exciting frequency generated by drilling string contact with the sidewall. But stick-slip frequencies of axial vibrations corresponded well with minor energy amplitudes. In conclusion, the stick-slip of the drill string may be characterized by torsional vibration. At the same time, there were intensive horizontal vibration and relatively weak axial vibrations. This study can provide as reference in stick-slip vibration characterization and removal strategy for eliminating it in ultra-deep wells drilling.