Patent ID: 8087904

Claim:
A hydraulic pumping unit for removing well fluids from a well, comprising: an electric motor; a reservoir for a hydraulic fluid; a variable volume piston pump having a drive shaft connected to said electric motor for powering said variable volume piston pump, said variable volume piston pump having a pump suction port connected to said reservoir and a pump discharge port; a sucker rod assembly disposed in the well for removing the well fluids from the well; a ram connected to said pump discharge port for receiving the hydraulic fluid from said variable volume piston pump and moving from a retracted position to an extended position, said ram disposed at and adapted for moving the sucker rod assembly in the well to a raised position when said ram is moved to the extended position; said variable volume piston pump adapted for moving the hydraulic fluid from said reservoir and into said ram, and moving said ram to said extended position, and for passing the hydraulic fluid from said ram into said reservoir, wherein pressure in said ram from a weight of the sucker rod assembly moves the hydraulic fluid from said ram, through said variable volume piston pump and into said reservoir to power said variable volume piston pump to turn said electric motor; and a control unit adapted for controlling flow rates of the hydraulic fluid through said variable volume piston pump for moving said ram between said retracted and said extended positions, wherein, during normal operation: said variable volume piston pump is powered by said electric motor to provide hydraulic fluid to said ram for extending said ram; and said variable volume piston pump is powered by hydraulic fluid from said ram so that resulting energy from said variable volume piston pump is primarily directed to turn said electric motor and generate electric power in retracting said ram.