Hongshan Zhao, Wenchang Wang, Kaixian An
Drilling Technology Research Institute, Sinopec Shengli Oilfield Service Corporation, Dongying City, Shandong Province, China.
School of Mechanics and Engineering Science, Shanghai University, 149 Yanchang Road, BOX189, Shanghai City, 200072, China.
Sci Rep. 2025 Aug 5;15(1):28483. doi: 10.1038/s41598-025-13880-w.
Stick-slip vibration is a common phenomenon in ultra-deep drilling that significantly impacts the failure of both drill bits and drill tools. The most direct and efficacious approach to alleviating the stick-slip vibration of the drill string in the downhole is to modify its external excitation. In recent years, the composite impact tools that can simultaneously offer axial and torsional excitation in the downhole have been applied, effectively reducing the stick-slip vibration of the drill string. However, the mechanical mechanism thereof remains undefined. In order to understand the nature of this phenomenon, A dynamic model of the drill string taking into account multi-directional excitations is presented. The governing nonlinear equations are obtained by using the Lagrangian approach, which take the work done by the multidirectional excitation into consider. The Hertz contact model is introduced considering the constraints of the wellbore, and the finite element node iteration method is employed to solve the dynamics equation of drill string. The axial vibration, torsion vibration and phase trajectory characteristics of the drill string under multidirectional excitation are analyzed, and the inhibitory effect of the excitations on stick-slip vibration is clarified. The results show that the vibration characteristics of the bottom hole assembly can be significantly altered through periodic axial and torsional excitations at higher frequencies, resulting in the emergence of high-frequency vibration responses. These responses exhibit a pronounced inhibitory effect on stick-slip suppressed.
粘滑振动是超深钻井中的常见现象，对钻头和钻具的失效有显著影响。缓解井下钻柱粘滑振动最直接有效的方法是改变其外部激励。近年来，能够在井下同时提供轴向和扭转激励的复合冲击工具得到应用，有效降低了钻柱的粘滑振动。然而，其力学机理尚不清楚。为了理解这一现象的本质，提出了一种考虑多向激励的钻柱动力学模型。采用拉格朗日方法得到了控制非线性方程，该方程考虑了多向激励所做的功。考虑井筒约束引入赫兹接触模型，采用有限元节点迭代法求解钻柱动力学方程。分析了多向激励下钻柱的轴向振动、扭转振动和相轨迹特性，阐明了激励对粘滑振动的抑制作用。结果表明，通过在较高频率下进行周期性轴向和扭转激励，可以显著改变井底钻具组合的振动特性，从而出现高频振动响应。这些响应表现出对粘滑抑制的显著抑制作用。
