Optimization method based on process control of a new-type hydraulic-motor hybrid beam pumping unit

Currently, beam pumping unit has become a research hotspot in the oilfield area. Nevertheless, filling process of the pumping unit horsehead causes large-amplitude variations of the motor toque and greatly reduces the efficiency of the system. This paper presents a new-type hydraulic-motor hybrid system which can store the hydraulic energy and realize power recovery of the beam pumping unit. Mathematical model is built and verified by experimental studies. Experimental and simulation results show that, first of all, energy recovery function of the designed hydraulic-motor hybrid system is demonstrated to be effective; besides, hydraulic pressure of the hybrid system should be set at the range of 15–25 MPa, and the system efficiency can be over 80%; what is more, in order to optimize the component efficiency, maximum displacements of the hydraulic pump and motor are considered to be respectively set higher than 70 cc/r and 40 cc/r; last but not the least, synchronous speed value of the hybrid system should be settled high to some extent to ensure the efficiency of the whole system as well as the components. This optimization method can be set forth in the optimization design of the beam pumping unit.