Pumping unit well pump indicator diagrams transformation model based on the discrete system

In view of the problems existing in the field of fault diagnosis of pumping Wells at home and abroad, that is, the indicator diagram cannot accurately reflect the down-hole working conditions, and the solution process of transforming the indicator diagram into the pump diagram model is cumbersome, a pump diagram transformation model based on discrete system is proposed. The sucker rod string is simplified into a multi-mass-spring system, the influence of oil on the swabbing movement of the rod string is considered, and the dynamic analysis of the mass nodes is made, and the differential equation of rod string movement is established. The approximate expressions of suspension point displacement, suspension point load and pump end load were substituted into the equation by Fourier series method. The equations were solved by mode superposition method and vibration solution formula of single-degree-of-freedom system, and the displacement expressions of arbitrary nodes of the rod were obtained. The Fourier coefficients of the pump end load expression were obtained by solving the suspension point load and comparing the coefficients. The pump end load expression and displacement expression were obtained, and the modeling was completed. The simulation results show that the model can accurately simulate the pump work diagram, which has practical engineering significance.