Abstract: In order to design the rod string and analyze failure mechanism, the dynamics analysis on rod string of surface driving screw pump must be conducted. A nonlinear dynamics model for describing the impact contact state between rotating rod and tube was presented. In consideration of the impact contact between rotating rod and tube that happens in any direction of well depth and well bore circumference, the dynamic gap element to describe the random impact contact state between rotating rod and tube was constructed. A rotating rod dynamics analysis method was proposed by combining the dynamic gap element with space beam element. This method has been applied to the B2-6-41 Well in Daqing Oilfield. It is shown that the relative error between calculated average value and actual test value of the rod torque at well head is 1.5 percent. The dynamic strength of rod string and the mount position of centralizer were calculated, according to the acquired deformation of rod string and its impact contact force with tube in the time domain. The designed rod string with this method can safely run in the well for longer time, which makes pump-inspection period over 550 days. This method can also be widely used in other Oilfields.

Key words: screw pump, rod string, impact contact, dynamics analysis, finite element method

摘要： 地面驱动螺杆泵抽油杆柱动力学分析是杆柱设计、失效机理分析的关键技术.针对细长抽油杆柱旋转运动时沿井深和井眼圆周方向与油管内壁产生碰撞接触的问题,建立了抽油杆柱非线性动力学模型.利用构造动力间隙元来描述旋转抽油杆与油管的随机碰撞接触状态,并与空间梁单元相结合,建立了旋转抽油杆柱动力学分析方法.在大庆油田B2-6-41等井的应用结果表明,井口扭矩计算平均值与实际测试值的相对误差为1.5%.根据求得的时域内抽油杆柱受力变形值以及与油管柱碰撞接触力,计算了抽油杆柱动强度和扶正器安放位置.利用该方法设计的抽油杆柱能够安全可靠地运行,使检泵周期超过550d.

关键词: 螺杆泵, 抽油杆, 碰撞接触, 动力学分析, 有限元法