铰接式钻具组合的动力学分析

Dynamic analysis of the hinged bottom hole assembly

应用有限单元法对铰接式钻具组合进行了动态分析 ,推导了铰接点单元的刚度矩阵和载荷列阵 ,同时考虑钻头的轴向激振和钻柱与井壁的相互作用 ,用 Newmark法在时域里分析了一种铰接式钻具组合的横向振动 ,并在频域里进行了讨论。分析表明 ,轴向扰动激起铰接钻具组合多阶谐波分量 ,钻头侧向力动态分量的幅值与井斜曲率成正比。数值结果表明 ,井眼扩大是钻具组合动态响应的一个重要影响因素 ,如果井眼扩大较小 ,钻具组合的振动表现有周期性 ,而当井眼扩大较大时 ,振动不再是周期性 ,且钻头侧向力动态分量的幅值增加。

Dynamic analysis of the hinged bottom hole assembly is presented by means of the finite element method. The stiffness matrix and load column of the element with the hinged point is derived. Both axial excitation and interaction between drill string and well wall are involved in the analysis. Lateral vibrations of a kind of hinged bottom hole assembly are analyzed in the time domain with the Newmark numerical integration method. They are also discussed in frequency domain. Results obtained show that axial disturbance induced the high order harmonic vibrations.Amplitude of dynamic side force on bit is basically proportional to the well curvature.Numerical results show that the enlargement of well bore is an important factor effecting response of BHA.When the enlargement of well bore is small the vibration is periodic.If the enlargement of well bore is large,not only the vibration is non periodic but also the amplitude of dynamic side force on bit becomes larger.