大位移井钻柱振动规律研究与应用

在大位移井钻井工程中钻柱受着各种振动，当各种振动共振时，钻柱承受着非常大的动载，很容易受损，同时，钻柱的振动影响着井壁的稳定，严重威胁着井下的作业安全。以大位移井近井底的钻柱为研究对象，分析了钻柱振动行为所遵循的规律。采用线性分析法，获得了大位移井钻柱横向振动和扭转振动的频谱方程。同时获得了钻柱各种共振频率的分布。经分析表明：大位移井钻柱的横向振动和扭转振动的共振频率与实际钻井转速非常接近，应合理选择转速以减小钻柱共振的发生。文章的分析研究为大位移井钻柱动态行为的研究提供了理论依据。

STUDY ON DRILL STRING VIBRATIONS IN EXTENDED REACH WELLS AND ITS APPLICATION

The drill string is under kinds of vibration forces when drilling extended wells. Once all vibrations become a resonance, the drill string will bear a very large dynamic load, which would tend to damage the drill string as well as destroying the wellbore stability. So the drill string vibrations severely threaten the downhole safety. This article takes the near-bottom drill string in an extended reach well as the subject to study the drill string vibration rules. By adopting the linear analysis method, the frequency spectrum equations for lateral vibrations and torsional vibrations are derived. And the resonance frequency distribution rule is obtained. From the analysis it can be seen that the resonance frequencies of lateral and torsional vibrations are very close to the actual rotary speed. So to choose a reasonable rotary speed can reduce drill string resonance. The analysis made in this article has much significance in providing a theoretic foundation for drill string dynamics study.