Study on operating performance and indicator diagram of rod pump production system under fault conditions

Key words:  rod pump  fault diagnosis  leakage  deficient liquid supply  indicator diagrams

Abstract:

The operating characteristic models of the pump valves under the conditions of normal case, gas influence, leakage influence and insufficient liquid supply were established according to the velocity of the well fluid sucked and discharged of pump barrel and the variation of the hydraulic pressure in the pump barrel. Based on the coupling rod-tube-fluid model, the simulation models of the rod-pump oil production system under fault conditions were obtained. The results show that simulation results are in good agreement with the measured surface dynamometer diagrams and the predicted average error of liquid production rate is less than 6％. This verifies the accuracy of the fault simulation models. Compared with steel rods, the absolute load of carbon fiber mixed rod is smaller, the loading and unloading lines are longer, and the harmonics are less and smoother. The gas and traveling valve leakage will reduce the resonance of sucker rod string at the completion of loading, while the gas, insufficient liquid supply and standing valve leakage will aggravate the resonance of the sucker rod string at the completion of unloading. Based on the simulation models, the indicator diagram library of flexible sucker rod pumping system under fault conditions can be obtained.