【作者】 冯代辉；

【导师】 朱才朝；

【作者基本信息】 重庆大学 ， 机械设计及理论， 2007， 硕士

【摘要】 有效地预测和控制井下钻头和钻柱动力学性能和运动规律,合理提高钻头和钻柱的强度,实现对井眼轨迹的精确控制是目前钻井工程中的关键技术问题。而解决这些问题的基础工作之一就是要建立合理可靠的钻头、钻柱系统动力学模型,找到钻柱在钻井过程中井下运动规律和力学性能。但由于钻柱结构庞大且复杂,无法通过物理实验来研究,且钻柱在钻进过程中不仅存在纵向振动、横向振动、和扭转振动,还存在三个方向耦合振动,一般受力分析方法很难求解。因此研究钻柱结构与井壁岩石互作用下系统的动力学特性,对实现钻柱系统运动规律和井眼轨迹的预测与控制,具有重要的理论意义和工程实用价值。论文把随机振动理论、有限元法、动力间隙元理论和非线性耦合问题的数值方法以及现代钻井技术结合起来,根据钻柱的运动和受力状态,通过综合考虑钻柱结构、边界条件和各种载荷的作用,把钻柱与井壁边界处理成多向摩擦接触,引入动力间隙单元,建立了实态工作状态下钻柱与井壁互作用下耦合系统的纵向、横向、扭转耦合振动非线性动力学模型,该模型不仅是一个几何和阻尼非线性问题,还是一个碰撞接触边界非线性问题,能够较为全面的反映钻柱系统在井下的实际动力学状态。利用有限元程序ABAQUS/EXPLICIT中心差分法对实际石油工程用井钻柱系统进行了动态仿真分析,研究钻柱在钻井过程中运动规律、力学性能、失效机理等。从仿真的结果中可以看出,钻柱系统的运动状态、动态响应分布都呈现出极其复杂的无规律性;在钻压、钻柱自重等外载荷的作用下底部钻具组合弯曲失稳后与井壁碰撞接触,这种接触力的位置和大小都呈现出极大的随机性,在自重、钻压等外载荷的作用下钻柱下部紧贴井壁运动,并产生了较大横向、纵向及扭转的耦合振动;在钻柱轴线方向上各井深处节点横截面方向的运动轨迹曲线呈无规则状。研究为实现钻头系统寿命的提高和井眼轨迹精度的动态优化,进而实现对钻柱系统运动规律和井眼轨迹的预测与控制提供了理论依据。更多还原

【Abstract】 It is the key technical issue in the drilling engineering that effectively predicting and controlling of dynamic performance and kinetics law, reasonably increasing the strength of drill bit and drill string, realizing the control of trajectory precession. And the solution to these problems is one of basic work to establish rational and reliable dynamic model for drill bit and drill string, which find the kinetic law and mechanical properties of drill string under well. However, the large and complex structure of drill string, the study is very hard by physical experiment, the drill string, in the drilling process, exist not only vertical vibration, lateral vibration and torsional vibration, but also the coupling of three direction vibration, the general stress analysis method is difficult to solve. Therefore, the studying of dynamic properties of drill string system under drill string structure and wall rock interaction is an theoretical and practical value to realize of predicting of kinetic law and controlling of trajectory precession.Paper combine the random vibration theory、finite element method、dynamic gap element theory、coupling nonlinear numerical theory and modern drilling technologies. According to the drill string kinetic and force state, comprehensive consideration of drill string structure、boundary conditions and role of various loads, introduction of dynamic gap element, the nonlinear dynamic model of drill string system is established, which couple vertical vibration、lateral vibration and torsional vibration, and which is not only a nonlinear geometry and damping problem but also nonlinear boundary condition problem. The dynamic properties of drill string system is more fully reflected under actual state.Through FEM program, ABAQUS/EXPLICIT central difference, the dynamic simulation analysis is ran about drill string system in the actual drilling engineering, which research kinetic law of drill string in the drilling process、mechanical properties、failure mechanism. From the simulation result, it can be see that the movement state and dynamic respond distribution of drill string system present complex and irregulation laws. BHA bend and buckle under outer load of WOB and self gravity, which contact the well wall, the size of contact force and contact position present great random, the BHA move close to well wall and great vibrate in vertical、lateral and torsional direction, even couple vibration. The transverse direction trajectory curve of various node on drill string axial direction exhibit random. The study conclusion provide theory foundation for enhance of drill bit system life and dynamic optimization of trajectory accuracy, then predicting kinetic laws of drill string and controlling the trajectory of well.更多还原