大斜度井全井钻柱动力学数值模拟研究

发布时间：2018-07-13 19:26

【摘要】：随着油气勘探工作的不断深入,大斜度井作为一种经济有效的钻采手段逐渐被业内使用。然而由于大斜度井井斜大、水平位移较长,钻井开发中摩阻扭矩高、井眼延伸困难、机械钻速低等问题突出。由于钻柱在井眼中的受力状态十分复杂,钻具静力学应用局限性及存在的问题更加突出,因此如何正确认识大斜度井钻柱动力学行为显得尤为重要。本文针对现阶段大斜度井钻井过程中钻柱动态力学行为认识薄弱的问题,在国内外文献调研的基础上,建立了基于有限元软件的大斜度井全井钻柱与井壁(套管壁)的有限元建模技术方法,结合室内台架实验及现场钻井数据,指导本研究进一步优化仿真分析过程,并在此基础上开展大斜度井全井钻柱动力学数值模拟应用研究,完善了大斜度井钻柱动力学理论与应用技术。首先,进行了大斜度井钻柱系统工况分析,并研究了大斜度井全井钻柱动力学研究中的关键问题。(1)钻柱与井壁的接触模型：根据三维井眼中钻柱与井壁的接触状态,对比有限元软件中的罚函数法、拉格朗日乘子法和扩展拉格朗日乘子法的优缺点,确定本文选用扩展拉格朗日乘子法；(2)钻井液阻尼模型研究：类比分析了海洋工程波浪力学中对直杆管柱在流体中的受力情况的研究成果,得到钻井液中运动钻柱的曳力系数,以此计算钻柱动力学分析中的钻井液阻尼力,使仿真分析更加结合实际；(3)钻头与岩石互作用研究：将钻柱与岩石接触的过程等效为摩擦模型,并在此基础上提出了钻压扭矩弱耦合模型,使仿真分析更贴合实际工况。其次,根据实钻井眼轨迹和钻具组合,建立了全井钻柱的有限元模型,实现了多组井深下的大斜度井全井钻柱动力学特性仿真计算,结合钩载、扭矩、接触力、加速度分布,研究了大斜度井钻柱动力学特性,实现了长度超过5000m的大斜度井钻柱的动力学特性仿真分析。在此基础上,结合现场PWD试验,验证了大斜度井全井钻柱动力学仿真分析方法的可行性与正确性。最后,进行了大斜度井全井钻柱动力学仿真技术应用研究。对作业过程中载荷传递规律及不同井身结构(井斜角、井深)参数下载荷传递规律差异进行分析,给出了钻井作业钻压施加、降摩减扭措施的指导性建议；通过对降摩减扭短节使用效果的仿真模拟,证明了本仿真技术能很好地满足实际工程需求；最终形成了形成了一个大斜度井钻柱系统动力学仿真分析模块,为大斜度井钻井设计、设备选型及钻井实践提供指导和帮助。
[Abstract]:With the deepening of oil and gas exploration, large deviated wells are gradually used as an economical and effective drilling and production method. However, due to large deviation, long horizontal displacement, high friction torque, difficult hole extension and low drilling speed, etc. Because the stress state of drill string in borehole is very complicated, the application limitation and existing problems of drilling string statics are more prominent, so it is very important to correctly understand the dynamic behavior of drill string in high inclination well. In view of the weak understanding of the dynamic mechanical behavior of drill string in the drilling process of large deviated wells at present, this paper is based on the domestic and foreign literature investigation. Based on the finite element software, the finite element modeling method of drilling string and lining (casing wall) for large deviated wells is established. Combined with laboratory test and field drilling data, the simulation and analysis process of this study is further optimized. On the basis of this, the application of numerical simulation of drilling string dynamics in large deviated wells is studied, and the theory and application technology of drill string dynamics in large deviated wells are improved. First of all, the working condition of drilling string system in high inclination well is analyzed, and the key problems in the research of drill string dynamics are studied. (1) the contact model between drill string and well wall: according to the contact state between drill string and well wall in 3D well, Comparing the advantages and disadvantages of the penalty function method, Lagrange multiplier method and extended Lagrange multiplier method in the finite element software, it is determined that the extended Lagrange multiplier method is used in this paper. (2) study on the damping model of drilling fluid: the research results of wave mechanics in ocean engineering on the force of straight pipe string in fluid are analyzed by analogy, and the drag coefficient of moving string in drilling fluid is obtained. In this way, the damping force of drilling fluid in the dynamic analysis of drill string is calculated, which makes the simulation analysis more practical. (3) study on the interaction between drill bit and rock: the process of drill string and rock contact is equivalent to the friction model. On this basis, a weak coupling model of drilling torque is proposed, which makes the simulation and analysis more suitable to the actual working conditions. Secondly, according to the actual drilling trajectory and the combination of drilling tools, the finite element model of the whole well string is established, and the simulation calculation of the dynamic characteristics of the whole well string under multiple sets of well depths is realized, combining with the distribution of hook load, torque, contact force and acceleration. In this paper, the dynamic characteristics of drill string in high slope well are studied, and the dynamic characteristics of drill string with a length of more than 5 000 m are simulated and analyzed. On this basis, the feasibility and correctness of the dynamic simulation analysis method for drilling string in large deviated wells are verified by combining with the field PWD test. Finally, the application of dynamic simulation technology of drilling string in large deviated well is studied. The difference of load transfer law and load transfer law of different well structure parameters (well inclination, well depth) during operation is analyzed, and the guiding suggestions for drilling operation to apply drilling pressure and reduce friction and torsion are given. The simulation results show that the simulation technology can meet the practical engineering requirements, and finally a dynamic simulation analysis module of drill string system with large slope is formed. It provides guidance and help for drilling design, equipment selection and drilling practice.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE921

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