考虑残余应变的连续油管井下屈曲行为理论研究

【作者】 刘健；

【导师】 练章华；

【作者基本信息】 西南石油大学 ， 油气井工程， 2006， 硕士

【摘要】 连续油管井下屈曲行为问题是连续油管井下作业成败的关键性问题。目前对它的研究只是将钻柱、套管柱和常规油管柱屈曲问题的研究结果直接用于连续油管，现场很多实例表明，这样做的偏差很大，连续油管因为残余应变而具有独特的井下屈曲行为。然而，一直以来理论研究带有残余应变的连续油管井下屈曲行为，都面临着研究方法上、力学上和数学上的巨大难题，没有取得很好突破和进展，还没有形成一套成熟的理论研究方法。 本文在前人对钻柱、套管柱和常规油管柱屈曲问题研究的基础之上，理论研究了带有残余应变的连续油管在斜直井中和等曲率弯曲井中的屈曲问题，在研究方法上、力学数学问题求解技巧方面取得了很大的进展。主要的研究成果如下： 1)通过分析连续油管作业机夹持块的作用，发现它能极大地改变连续油管从卷筒上卷出时带有的螺旋弯曲应变。假设连续油管经过夹持块作用以后，下入井内的初始形态为正弦形态，以此来考虑连续油管残余应变的影响。以一种有形的、容易描述的初始形态来考虑无形的、复杂的、难于描述的残余应变。 2)采用了能量法分析连续油管井下的屈曲行为，成功地建立了描述连续油管在斜直井和等曲率弯曲井中初始正弦形态和最终屈曲形态(正弦屈曲或螺旋屈曲)的数学模型。 3)从最基本的力学原理出发，推导出了连续油管在斜直井中和等曲率弯曲井中的弯曲应变能公式、轴向外载做功公式、重力分量做功公式。 4)根据最小势能原理和机械能守恒原理，建立了连续油管在斜直井和等曲率弯曲井中的正弦屈曲平衡方和螺旋屈曲平衡方程。在对弯曲应变能公式、轴向外载做功公式、重力分量做功公式三个公式进行积分时，运用了复数欧拉公式和复数级数，将积分中的数学难题—超越三角函数积分，展开成普通三角函数多项式积分，并成功地完成了几百项的普通三角函数多项式积分工作。 5)最终推导并得出了4个考虑残余应变的连续油管屈曲载荷计算新公式：斜直井中的①正弦屈曲载荷计算新公式，②螺旋屈曲载荷计算新公式；等曲率弯曲井中的③正弦屈曲载荷计算新公式，④螺旋屈曲载荷计算新公式。 从所举油田作业实测数据来看，本文所推导的新公式和得出结论是和现场吻合的，正确的。更多还原

【Abstract】 The problem of the behaviors of coiled tubing down-hole buckling is the key of the success of coiled tubing down-hole operation. Presently, the study did for it just directly used the results of study buckling behaviors on drilling pipe, casing string, conventional oil tubing to deal with coiled tubing; many filed cases indicate that to do so will give big differences. Because of residual strain, coiled tuning has special down-hole buckling behaviors. However, theoretically researching the down-hole behaviors of coiled tubing with residual strain has been facing with much difficult problems on researching method, mechanics and mathematics all the time. No good improvements and progresses have been made; no mature theoretical researching methods have been got.Based on the formers’ results of study buckling behaviors on drilling pipe, casing string, conventional oil tubing to coiled tubing, this thesis theoretically studied coiled tubing with residual strain buckling in straight deviated well and constant-curvature well. Big progresses have been made on researching methods and solving skills of mechanical-mathematical problems. The main studying results of this thesis as followings:1) Though analyzing the function of the gripper in the coiled tubing equipment, that it can greatly change the helical bending stain from the coiled tuning reel has been found. After acting with the gripper, the initial configuration of coiled tubing in the well assumes a sinusoidal configuration. By the assumption the effect of coiled tuning’s residual strain has been considered. Using a tangible, easily descriptive initial configuration to consider the bodiless, complex and difficultly descriptive residual strain 。2) Energy method has been used to analyze the behavior of coiled tubing down-hole buckling. The mathematical modes of the initial sinusoidal configuration and the final buckling configuration have been successfully made.3) From the basic mechanical theories, the formula of bending stain energy, the formula of work done by the external force and the formula of work done by the weight component have been derived.4) According to the principle of minimal potential energy and the principle of conservation of energy. The sinusoidal buckling and helical buckling equilibrium更多还原