Computer Simulation Of The Dynamic Characteristics For Combined Sucker Rod String

Rod pumping approach is in the dominant position now. The fiberglass sucker rod is widely used due to its small density, lightweight and corrosion resistance. Therefore predetermining the actual dynamic characteristics of steel and fiberglass combined sucker rod in a hole and establishing its dynamic mathematical model is a difficult problem to be solved urgently.Dynamic characteristics of combined rod are simulated by using finite element software in this paper, the detail contents are as follows:I According to the one dimension wave-motion with damping and gravity force, a detail finite element deduction process is given.2 Natural frequency is solved by using modal analysis and the qualitative relationship between natural frequency and the ratio of fiberglass in sucker rod is found.3 In light of the kinetic characteristic of the polished rod, its transient kinematic and dynamic characteristics are simulated at different periods of a cycle. It is found that the kinematic parameter and force vs. time curves and the related dynamometer are described accurately by comparing with the actual measurements. The dynamic characteristic and the force behavior will provide a basis for designing and optimizing pumping units.4 The dynamic process of multi-stage steel sucker rod, multi-stage fiberglass and steel sucker rod are simulated in the same work condition. Some important conclusions are obtained by analysis and comparing their relative curves. These results could provide qualitative and quantity theoretical foundation for selecting correct parameter of pumping unit.