Socker-rod pumping unit with hydraulic transmission mechanism in the rod string

In existing sucker-rod pumping units the lower end of the rod string which hanged from the wireline hanger is directly connected with the plunger of the well pump. So, the plunger of the well pump is moving up and down according to the movement of the hanger after the deformation is ended and then the fluid is raised to the surface from the formation. The wireline hanger is affected by the weights of the rod string, the lifted fluid column and the dynamic loads when it is in an upward movement. To reduce the loads on the wireline hanger and increase the operating efficiency of the pumping unit, a hydraulic transmission mechanism operating on the principle of the hydraulic press was used in the intermediate part of the rod string. The rod string hanged from the wireline hanger is connected to the rod-shaped piston of the hydraulic transmission mechanism, and the groove-shaped piston of the mechanism is connected to the rod string of the well pump plunger. Due to the installed hydraulic transmission mechanism in the rod string, the plunger of the pump moves downwards in the upward movement of the rod string, and vice versa in the downward movement of the rod string, the plunger of the pump rises and lifts the liquid. As a result, the maximum and minimum loads on the hanger are reduced by more than 2 times. Keywords: rod pump unit; pump compressor pipe; well pump; rod string; wireline hanger; deformation; stroke length; inertial forces; frictional forces; hydraulic press; hydraulic transmission mechanism; dynamometer card.