水平受压柔性旋转梁屈曲特性分析及试验研究

发布时间：2018-08-08 10:34

【摘要】：水平井作业中常采用柔性钻柱,钻柱的稳定性直接影响到钻井的成败,而钻柱屈曲载荷的预测一直是钻井行业面临的一项挑战。钻柱在钻进过程中的失稳可能导致严重的问题,例如钻柱的疲劳损伤,井下工具的过度磨损,随钻测量的失效,钻头的过度损耗,钻头的粘滑运动,井壁的不稳定性和冲蚀以及低效率钻进等。因此,为保证水平井钻井的成功,理解和掌握水平井钻柱的稳定性和屈曲行为机理至关重要。本文分别分析了水平受压旋转梁的静力学屈曲行为和动力学屈曲行为。静力学屈曲行为的研究:以受水平圆管约束的细长管柱为分析模型,考虑摩阻和边界约束,建立受约束管柱非线性屈曲行为的静力学微分方程。采用微分求积法(DQ法)和Newton迭代法求解控制方程,分析简支—简支(Simply Supported-Simply Supported)、简支—固支(Simply Supported-Clamped)、固支—简支(Clamped-Simply Supported)和固支—固支(Clamped-Clamped)这四种边界约束条件对钻柱稳定性的影响;同时,分析摩擦系数的变化对水平井钻柱的屈曲临界载荷及屈曲变形的影响规律;分析钻柱自身的重力对水平井钻柱屈曲问题的重要影响。动力学屈曲运动的分析:以旋转作业状态下的水平井钻柱为分析对象,描述钻柱的动态屈曲行为,拟建动力学屈曲方程。应用能量法和最小势能原理推导出水平井钻柱的正弦屈曲临界载荷和螺旋屈曲临界载荷的计算公式。改造实验室内的水平井钻柱动力学特性模拟试验装置,进行水平井钻柱静力学屈曲和动力学屈曲的模拟试验。通过模拟试验的方法分析水平井作业中轴向载荷的传递效率,并得到摩阻力变化趋势。采用摩阻力增量加速度判断法结合试验数据判定钻柱分别发生正弦和螺旋屈曲的临界载荷,与数值计算结果对比分析。利用模拟试验研究了转速对水平井钻柱动态屈曲运动的影响规律,观察动态屈曲振动的幅值和轴心轨迹的变化规律。研究发现:随着转速的增加,动态屈曲振动的幅值以及振动频率会变大;钻柱转速由17r/min增大到107r/min的过程中,螺旋屈曲临界载荷由静态时的86%降低到75%;转速达到107r/min时,若加载载荷超过螺旋屈曲临界载荷,会将钻柱的动态屈曲运动由蛇形运动转变为涡动运动。
[Abstract]:Flexible drill string is often used in horizontal well operation, the stability of drill string directly affects the success or failure of drilling, and the prediction of buckling load of drill string is always a challenge to drilling industry. The instability of drill string during drilling may lead to serious problems, such as fatigue damage of drill string, excessive wear and tear of downhole tools, failure of measurement while drilling, excessive loss of drill bit, movement of stick-slip of drill bit, etc. Instability and erosion of wellbore and low efficiency drilling. Therefore, in order to ensure the success of horizontal well drilling, it is very important to understand and master the stability and buckling behavior mechanism of horizontal well drill string. The static buckling behavior and dynamic buckling behavior of horizontally compressed rotating beams are analyzed in this paper. Study on buckling behavior of statics: a statics differential equation of nonlinear buckling behavior of a confined string is established by taking the slender pipe string constrained by a horizontal circular tube as an analytical model and taking into account friction and boundary constraints. The differential quadrature method (DQ method) and Newton iterative method are used to solve the governing equation. The effects of four boundary constraints, namely, Simply Supported-Simply Supported), simple support (Simply Supported-Clamped), fixed simple support (Clamped-Simply Supported) and fixed branch fixed support (Clamped-Clamped), on the stability of drill string are analyzed. The influence of the variation of friction coefficient on the buckling critical load and buckling deformation of the drill string in horizontal wells is analyzed, and the important influence of the gravity of the drill string on the buckling problem of the drill string in horizontal well is analyzed. Dynamic buckling analysis: the dynamic buckling behavior of the drill string is described and the dynamic buckling equation is proposed. The formulas of sinusoidal buckling critical load and spiral buckling critical load of drilling string in horizontal wells are derived by using the energy method and the principle of minimum potential energy. The static and dynamic buckling tests of horizontal well drill string were carried out by modifying the dynamic simulation test device of horizontal well drill string in laboratory. The transfer efficiency of axial load in horizontal well operation is analyzed by simulation test, and the variation trend of friction resistance is obtained. The critical loads of sinusoidal buckling and spiral buckling of drill string were determined by the method of incremental acceleration judgment of friction resistance combined with test data, and the results were compared with the results of numerical calculation. The effect of rotating speed on dynamic buckling motion of drill string in horizontal wells was studied by simulation test. The amplitude of dynamic buckling vibration and the variation of axial trajectory were observed. It is found that the amplitude and frequency of dynamic buckling vibration increase with the increase of rotational speed, and the critical load of spiral buckling decreases from 86% to 75% in the process of increasing the rotation speed of drill string from 17r/min to 107r/min, and the critical load decreases from 86% to 75% when the rotation speed reaches 107r/min. If the loading load exceeds the critical load of spiral buckling, the dynamic buckling motion of drill string will change from snake motion to vortex motion.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE243

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