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随着钻井技术的不断进步,油气井已由早期的铅直井发展成了当今的斜直井,水平井,平面曲井,甚至三维空间曲线形状曲井.井内钻柱屈曲性能的研究对钻井工程的成败尤为重要,迫切需要建立分析三维曲井内钻柱屈曲性能的平衡方程.本文基于Love的空间弯扭杆平衡方程,考虑到井壁的径向约束条件,导出了一套用于三维曲井内钻柱非线性屈曲分析的平衡方程.公式引入了三维曲井的井眼轴线曲率和挠率所带来的影响.对于径向受井壁约束的钻柱,上端同时作用有轴向压力和扭矩,并计及自重,给出了非线性屈曲分析平衡方程的详细推导过程.值得注意的是,现有文献中用于分析直井和平面曲井内钻柱屈曲性能的平衡方程,可由三维空间曲井内钻柱非线性屈曲分析平衡方程退化得到.期望本文导出的平衡方程能为工程上三维曲井内钻柱的非线性屈曲分析提供理论基础.
With the continuous improvement of drilling technology, oil and gas wells have been developed from the early vertical wells into the current horizontal well, horizontal well, planar well, and even curved three-dimensional space shape well. Success or failure is particularly important and there is an urgent need to establish a balance equation that can be used to analyze the buckling behavior of the drillstring in a three-dimensional well.In this paper, based on the balance equation of Love bending-torsion bar, taking into account the radial constraint of the wellbore wall, EQUAL EQUATION FOR NONLINEAR BUCKLING ANALYSIS The formula introduces the effect of the wellbore axis curvature and the deflection of a three-dimensional well.The axial forces and torques act simultaneously on the upper end of a drill string constrained by the wellbore Considering its own weight, a detailed derivation of the nonlinear buckling analysis equilibrium equation is given.It is noteworthy that the balance equation used in the existing literature to analyze the buckling behavior of the drill string in a vertical well and a planar well may be derived from a drill string in a three-dimensional space Nonlinear buckling analysis Equilibrium equations are degenerated.It is hoped that the equilibrium equation derived in this paper can provide a theoretical basis for the nonlinear buckling analysis of drillstring in 3D curved wells.