井下底部钻具组合高频扭转振动分析

Analysis on Downhole High-Frequency Torsional Oscillation of Bottom Hole Assembly

高频扭转振动(HFTO)严重影响了钻具工作的安全性及可靠性。为了明确HFTO的作用机理,制定合理可靠的减振策略,对井下新型近钻头测量短节采集的数据进行了处理及解释,分析了井下HFTO的频率、振幅以及黏滑与HFTO耦合作用。利用ANSYS建立底部钻具组合简化分析模型,并使用模态分析模块求解钻具扭转振动固有频率及振型。在模态分析的基础上进行谐响应分析,通过施加大小不同的周期作用力来模拟钻压和扭矩,得到钻具的扭转振动响应。研究结果表明:模态分析结果与实际钻井情况相符合;谐响应分析表明发生HFTO时对钻头处扭矩大小更敏感,可以通过减小扭矩缓解高频扭转振动。研究结果可为底部钻具组合设计和钻井参数优化提供理论指导依据,降低HFTO对钻具的损害。

High-frequency torsional oscillation(HFTO)has seriously affects the safety and reliability of drilling tools.In order to clarify the mechanism of HFTO and formulate a reasonable and reliable vibration reduction strategy,the data collected from the new near-bit gauging nipple in the wellbore were processed and interpreted,and the frequency and amplitude of HFTO in the wellbore as well as the coupling effect of stick slip and HFTO were analyzed.Then,the ANSYS dynamic analysis module was used to build a simplified analysis model of BHA,and modal analysis module was used to solve the natural frequency and oscillation mode of torsional vibration of drilling tools.Finally,on the basis of modal analysis,the harmonic response analysis was carried out;and by means of applying different cyclic active forces to simulate the weight on bit and torque,the torsional vibration response of the drilling tool was obtained.The study results show that the modal analysis results are consistent with the actual drilling situation.The harmonic response analysis shows that HFTO is more sensitive to the torque at the bit,and it can be alleviated by reducing the torque.The study results provide theoretical guidance basis for the design of BHA and the optimization of drilling parameters,so as to reduce the damage of HFTO to drilling tool.