游梁式抽油机悬点负载耦合动力学建模

Coupled Dynamic Modeling for Polished Rod Load of Beam Pumping Unit

建立了描述游梁式抽油机悬点负载动态特性的耦合动力学模型.采用多自由度的弹簧-质量-阻尼器机械动力学系统描述抽油杆柱振动特性.综合考虑有杆泵抽汲过程中泵腔内气体可压缩性、泵腔压力变化、泵阀局部阻力等因素的影响,建立了泵腔压力、进泵流体流量、泵腔内液体体积与柱塞运动之间相互关系的数学模型,得到一组描述有杆泵动态抽汲过程的新模型,确定了求解抽油杆柱振动模型的井下边界条件.采用时步有限元方法对所建杆-泵耦合动力学模型进行仿真计算.油田现场应用表明,所建模型具有较高精度,可用于抽油井负荷、泵效、扭矩和平衡度等工况参数预测及故障诊断.

A coupled dynamic model for describing the dynamic performance of the polished rod load of beam pumping units was established. The multi- degree- of-freedom spring- quality-damper mechanical dynamic system was adopted to describe the vibration characteristic of the sucker rod string. The compressibility of the gas in the pump barrel, the changing pressure in the pump barrel and local resistance of the pump valve were comprehensively considered. The new equations describing the dynamic sucker rod pumping process were set up in order to determine downhole boundary conditions to solve the sucker rod string vibration model,which represented the interrelationship between the pressure in the pump barrel, the fluid flow into the pump barrel, the volume of the fluid in the pump barrel and the movement of the plunger piston. The time-stepping finite element method was employed to simulate the rod-pump coupled dynamic model. Oil field application shows the fairly effectiveness and accuracy of the new model,which can be used for the prediction of the working condition parameters such as the load, pump efficiency, torque and balance,and the fault diagnosis.