径向井钻杆截面变形的三维有限元仿真

径向井是一种新型高效的原油开采技术。径向井钻杆的截面变形与圆管塑性弯曲成型、圆管截面弯曲稳定性有一定的联系,但研究问题的出发点不同,使得这些研究所采用的模型、实验设备并不能直接用于研究径向井钻杆弯曲时的截面变形。文中将三维有限元法用于研究径向井钻杆的截面变形,验证了平截面假设的适用性及变形后断面形状的椭圆性。仿真结果显示,钻杆弯曲时其截面的长、短轴的变化是独立的;截面周长随曲率增大呈线性增加。特别是短轴的变化,随载荷值改变呈现出不同的变化趋势。该结果为选取钻杆最佳转向曲率、制定钻进工艺参数提供了依据。仿真结果与实验情况相吻合。

3-D SIMULATION ON THE CROSS-SECTION DEFORMATION OF URRS DRILL-PIPE WITH FINIT ELE-MENT METHOD

The ultra-short radius radial system (URRS) is a new highly efficient technology of oil recovery.When the drill-pipe of URRS turns to horizontal from vertical,it will be bent over and back several times,and the cross-section will produce plastic deformation.For the drilling smoothly,the short diameter of the drilling pipe cross-section shall be changed least.The drill-pipe deformation is similar to plastic bending forming and stability of cylindrical shell.The beam element cannot be used to study the cross-section deformation in URRS though it is a suitable element for studying common drill-pipe.3-D simulation of finit element method (FEM) was used to study drill-pipe cross-section deformation.The suppositions of planer and elliptical of drill-pipe cross-section were verified. Simulation shows that the dimension variation of long and short bending axes are independent,and the circumference simply increases with bending curvature.The dimension of short bending axis increases or decreases at the mercy of loads and the thickness of pipe.The simulation is useful to optimize the curvature of turning and select technical parameters.The simulation results are confirmed with experiments.