LIU Yan-qiang. Method of Equilibrium Differential Equation for Analysis of Strength of Large Deflection Drill String[J]. Applied Mathematics and Mechanics, 2000, 21(11): 1165-1171.
 Citation: LIU Yan-qiang. Method of Equilibrium Differential Equation for Analysis of Strength of Large Deflection Drill String[J]. Applied Mathematics and Mechanics, 2000, 21(11): 1165-1171.

# Method of Equilibrium Differential Equation for Analysis of Strength of Large Deflection Drill String

• Rev Recd Date: 2000-06-05
• Publish Date: 2000-11-15
• To counter the strength problem of drill string in well of large curvature and small diameter,well axis was taken as datum axis.Based on description of deflection of well axis and on analysis of three dimensional forces of a small section of drill string,equilibrium differential equations of large deflection drill string were established.The internal forces were found by Longe-Kutta method.The stresses were found by using them and the strength prerequisite was established.Stresses of drill string in lateral horizontal well H767 were computed.The results are in agreement with those of finite element model and soft-rope rigidified model.But the method is simpler for computation than finite element model and is more perfect than soft-rope rigidified model.Curvature of the well is too large and there is stress concentration so that the fraction accident of drill string occurs.
•  [1] 刘延强,吕英民.环空钻柱结构三维非线性分析[J].应用数学和力学,1994,15(3):259-272. [2] LIU Yan-qiang.Strength Analysis of three-dimensional large deflection drill string in annulus[A].In:CHIEN Wei-zang Ed.Proceeding of 3rd International Conference on Nonlinear Mechanics[C].Shanghai:Shanghai University Press,1998,8:301-304. [3] 刘延强.大挠度钻柱强度分析和简化方法[A].见:杜庆华编.力学与应力工程[C].北京:中国林 业出版社,1998,413-416. [4] 刘延强,蔡强康,吕英民.三维井眼轴线的数值模拟计算[J].石油大学学报,1990,14(3):45-54.

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