全井钻柱系统耦合振动多体动力学模型的建立与算例分析

A multibody dynamical model and example analysis of full hole drillstring for fully coupled vibrations

基于绝对节点坐标法建立全井钻柱系统的多体动力学模型,研究系统的耦合振动现象;将大长细比柔性钻柱离散为绝对节点坐标梁单元,讨论梁单元格式,并研究井口、钻头处边界及钻柱与井壁的接触/摩擦模型,给出包含绝对节点坐标梁单元的钻柱系统运动方程;采用向后差分法求解微分-代数方程组,开发多体动力学求解器及相应的前、后处理器。通过直井、定向井算例分析了全井钻柱系统的轴向、扭转、横向耦合振动特性,结果表明本文提出的力学建模和数值分析方法可实时捕捉到钻柱系统的耦合振动现象,能够在钻柱系统动力学研究和工程应用中发挥作用。

In this investigation, a multibody dy-namical model for full hole drillstring system is presented based on the absolute nodal coordinate formulation （ANCF）. The fully coupled vibrations are studied. The drillstring is modeled with the ANCF beam element. The absolute nodal coordi-nate formulation of the beam element as well as the boundary conditions at wellhead and bit, and the contact/friction model between drilstring and wellbore are also investigated. The dynamic gover-ning equation for full hole drillstring system is given and solved by the backward differentiation for-mulation （BDF） for differential algebraic equations （DAEs）. A multibody dynamic solver with corre-sponding pre/post processor is developed. The numerical examples of straight and directional holes for fully coupled vibrations including axial, torsional and lateral show that the proposed model and numerical methods can capture the coupling vibration phenomenon of drillstring. It can play a certain role in drillstring dynamics researches and engineering applications.