深井钻柱的横向振动浅论

LATERAL VIBRATION OF DRILL STEM IN DEEP WELL

全面探讨了钻柱底部横向振动的产生、传播和消失过程。分析表明，横向振动只发生并存在于钻柱底部；底部钻具的屈曲、动力失稳和钻柱与井壁的碰撞是引起横向振动的直接原因；由钻头与地层相互作用引起的振动能，很大部分被螺旋屈曲段钻柱消耗；涡动和碰撞引起的中性点及中性支以上的振动，在向上传播过程中被钻井液阻尼抑制；钻柱轴向力影响振动频率和波的传播；中性点是危险点，但不是能量陷落点。

This paper discuss the process of creation, transmit and vanish of lateral vibration in bottom of drillstem. Analysing shows that lateral vibrations create and exist in bottom of drill stem only. The causes producing lateral vibration relate directly with buckling of BHA, dynamic unstable and collision between well wall and drillstem. The vibration energy caused by interaction of bit and formations is consumed by spiral buckling stem. Vibration above neutral point of stem caused by eddy movement and collision and inhibited by drilling fluid damp during transmitting upward. The axial force effect vibration frequency and wave transmitting. Neutral point is dangerous but is not energy trap point.