A New Model for Calculating the Ideal Beam Counterbalance Weight for a Pumping Unit

In order to calculate the beam counterbalance adjustment weight accurately and ensure the safe and energy-efficient operation of beam pumping units, it is necessary to conduct research on the beam counterbalance weight adjustment model for beam pumping units. This paper presents the results of an analysis of the quick-return characteristics of beam pumping units. Results indicated that the running time of upstroke was not equal to that of down stroke. Further, the calculation formula for the average output power both in upstroke and downstroke of beam-balanced pumping units were proposed. Then, according to the balance principle of maintaining the equality of motor powers during upstroke and downstroke, a new calculation model for beam counterbalance weight of beam-balanced pumping units was derived by using the relationship between the counterbalance weight’s average power change and the motor’s average power change. It was shown from the case calculation that the difference of motor powers between upstroke and downstroke was quite narrow and the balance principle of the equality of motor powers during upstroke and downstroke could be more effectively satisfied when the counterbalance weight was adjusted by means of the new model. The longer the upstroke (downstroke) ran, the larger (smaller) the adjustment on the beam counterbalance weight. When the running time of upstroke and downstroke was almost equal, the new model and simplified model produced similar results. The results suggest that the beam pumping units whose upstroke running time was not equal to downstroke running time could be better balanced when the counterbalance weight was adjusted by means of the new power curve method-derived calculation model of beam counterbalance weight.