下部钻柱与井壁接触对钻柱失效的影响

Contact interaction between bottom drillstring and borehole wall and its effect on drillstring failure

史玉才 孙铭新 管志川 阎振来

SHI Yucai SUN Mingxin GUAN Zhichuan YAN Zhenlai

中国石油大学石油工程学院，山东东营　257061 胜利石油管理局钻井工艺研究院，山东东营　257017

College of Petroleum Engineering, China University of PetroleumEast China, Dongying 257061, China Oil Drilling Research Institute, Shengli Petroleum Administration Bureau, Dongying 257017, China

在石油钻井中，下部钻柱与井壁之间存在十分强烈的碰摩作用，影响下部钻柱的横向运动状态，还可能诱发或加剧下部钻柱失效。应用下部钻柱运动状态分析模型，模拟研究了下部钻柱与井壁接触对钻柱失效的影响机理及规律。研究表明，下部钻柱与井壁的碰摩作用使下部钻柱反向涡动，产生高频的交变弯曲应力，会加速下部钻柱疲劳破坏；下部钻柱与井壁接触点处存在较大的高频冲击力，并且接触区域靠近钻铤螺纹联结处，更容易诱发螺纹联结处失效，该研究成果可为预防钻柱失效提供理论依据。

During drilling, the collision-friction interaction between the bottom drillstring and the borehole wall is extremely intense, which will exert effect on the lateral movement of drillstring and result in bottom drillstring failure or make it worse. Based on using a status analyzing model of the bottom drillstring, the mechanism and law of the effect on bottom drillstring failure due to the contact interaction is simulated and analyzed. It is shown that the contact interaction enables bottom drillstring to whirl backward, and then an alternate bending stress with higher frequency is produced. So the drillstring fatigue failure could be accelerated. At the same time, a quite strong wallop force of high frequency is produced on the contacting point, and the contacting zone is next to the screw coupling of drill collars. It will easily result in the failure of screw couplings. The research results provide theoretical basis for the prevention of drillstring failure.