基于数值模拟的钻柱谐振响应研究

HARMONIC RESPONSE STUDY OF DRILL STRING BASED ON NUMERICAL SIMULATION

钻柱振动是钻柱疲劳失效的主要原因,特别是在气体钻井过程中,井眼内缺少钻井液的润滑减震作用,钻柱振动更为强烈。文章建立了钻柱振动有限元数值模型,采用SUBSPACE法对钻柱进行模态分析,计算出了钻柱纵向振动各阶固有频率;并利用FULL法分别对三牙轮钻头和空气锤激励时钻柱的谐振响应情况做了计算,对其响应位移和响应轴力进行了详细研究,得出使用三牙轮钻头时钻柱在低阶频率处纵向共振响应位移最大,对钻柱的损害最大;使用空气锤时,钻柱在高阶频率处易发生共振,响应轴向力较大。

The primary cause of drill string fatigue failure is vibration.The drill string vibration is more intense in air drilling because lacking drilling fluid.The finite element numerical model of drill string vibration was established,and the modality of drill string was analyzed by SUBSPACE,the natural frequencies of drill string longitudinal vibration were calculated.The harmonic response of drill string was analyzed by FULL.The response displacement and response axle stress were studied in detail.When using tricone bit,the response displacement of drill string was the biggest in low-order frequency and the damage was also the biggest.It was easy for drill string resonance in high-order frequency when the exciter was air hammer,and response axle stress was bigger.