Pumps are provided, more particularly piston type pumps having increased energy efficiency, systems incorporating such piston type pumps, and methods of operating piston type pumps. The pumps are suitable for pumping of oil from an oil well or for pumping other liquids such as ground water, subterranean liquids, brackish water, sea water, waste water, cooling water, gas, coolants, and the like.

An exemplary pump jack system (10) is operable to cause well liquid to be pumped to the surface by a subsurface well pump (29). The exemplary system includes a driver (42) that is in rotatable connection with a pump/motor (48). The pump/motor is a rotary type variable output positive displacement pump/motor that delivers working liquid at a selectively variable flow rate in closed liquid connection to a motor/pump (38). The exemplary motor/pump includes a rotatable output coupler (40) that is in operative connection with a gearbox (34) which causes the pump jack to undergo reciprocating motion. The motor/pump is a rotary type positive displacement motor/pump that is in closed liquid connection with the pump/motor liquid inlet of the pump motor. The pump/motor is operable to deliver working liquid flow therefrom to drive the motor/pump at a selectively variable speed while the driver operates at a generally constant rotational speed. Return force which acts on the motor/pump during at least a portion of the pump jack cycle is operative to cause the motor/pump to urge working liquid toward the pump/motor which assists the driver in pump/motor operation.

Methods for operating a decoupled long stroke pump to pump treatment fluid to a wellbore are provided. The decoupled long stroke pump has relatively long stroke plungers that can be powered by hydraulics, linear electric motors, mechanical long stroke mechanisms, linear actuators, or any other device that can provide a linear force to the plungers. Such long stroke pumps have the suction and discharge strokes decoupled such that an absolute linear flow rate without pressure pulses on the suction or discharge can be produced. Any desired flow profile of the treatment fluid can be produced via the decoupled long stroke pump.

Methods for operating a decoupled long stroke pump to pump treatment fluid to a wellbore are provided. The decoupled long stroke pump has relatively long stroke plungers that can be powered by hydraulics, linear electric motors, mechanical long stroke mechanisms, linear actuators, or any other device that can provide a linear force to the plungers. Such long stroke pumps have the suction and discharge strokes decoupled such that an absolute linear flow rate without pressure pulses on the suction or discharge can be produced. Any desired flow profile of the treatment fluid can be produced via the decoupled long stroke pump.

A pump jack with counterbalance system is provided, including a supporting structure, a linear actuator with a housing and a shaft, a first pulley carried by the shaft, a second pulley fixed above the first pulley, an elongate flexible member, and a weight cared by the shaft. The housing is vertically oriented and mounted to the supporting structure above a ground surface. The shaft has a first end received within the housing and a connection end that extends out of the housing and carries the first pulley and the weight. The linear actuator drives the shaft between extended and retracted positions. The elongate member passes around the pulleys and has a first end fixed relative to the housing and a second end connected to a surface rod, such that reciprocating movement of the shaft causes the surface rod to move vertically and the weight to act as a mechanical counterbalance.

An exemplary pump jack system (10) is operable to cause well liquid to be pumped to the surface by a subsurface well pump (29). The exemplary system includes a driver (42) that is in rotatable connection with a pump/motor (48). The pump/motor is a rotary type variable output positive displacement pump/motor that delivers working liquid at a selectively variable flow rate in closed liquid connection to a motor/pump (38). The exemplary motor/pump includes a rotatable output coupler (40) that is in operative connection with a gearbox (34) which causes the pump jack to undergo reciprocating motion. The motor/pump is a rotary type positive displacement motor/pump that is in closed liquid connection with the pump/motor liquid inlet of the pump motor. The pump/motor is operable to deliver working liquid flow therefrom to drive the motor/pump at a selectively variable speed while the driver operates at a generally constant rotational speed. Return force which acts on the motor/pump during at least a portion of the pump jack cycle is operative to cause the motor/pump to urge working liquid toward the pump/motor which assists the driver in pump/motor operation.

Embodiments of the present invention relate to lifting and lowering loads more efficiently and also more economically than known systems. This invention is the continuous movement by mechanical means of a moving crank shaft force point to a desired advantageous position at a desired advantageous moment to achieve improved geometry resulting in a desired low torque factor for a reduced net torque when lifting or lowering an unbalanced load with a beam with a fulcrum and connected to a load and an effort. In one embodiment, a walking beam well pumping unit, the lifting and lowering of the well load can be caused by the reciprocating motion of a beam tipping on a fulcrum and with an effort force point continuously substantially vertically disposed with the moving crank shaft force point. Potentially reduced net torque might allow longer life speed reducers, smaller speed reducers, and longer reciprocating vertical stroke length.

A pump jack with counterbalance system is provided, including a supporting structure, a linear actuator with a housing and a shaft, a first pulley carried by the shaft, a second pulley fixed above the first pulley, an elongate flexible member, and a weight cared by the shaft. The housing is vertically oriented and mounted to the supporting structure above a ground surface. The shaft has a first end received within the housing and a connection end that extends out of the housing and carries the first pulley and the weight. The linear actuator drives the shaft between extended and retracted positions. The elongate member passes around the pulleys and has a first end fixed relative to the housing and a second end connected to a surface rod, such that reciprocating movement of the shaft causes the surface rod to move vertically and the weight to act as a mechanical counterbalance.

Pumping machine (650, 750) comprising: at least two tubular elements (651, 751) containing pressurized gas and extending vertically in parallel and interconnected between them by means of a connecting element (652, 752); andan electromechanical lifting system (600, 700) comprising a first cylinder (601, 701), interconnected to the tubular elements (651, 751) and comprising a substance compressible by a piston (601b, 701b); and a screw (602, 702) with a vertical axis Y coinciding with the axis of the pumping machine (650, 750). The screw (602, 702) is inserted inside a second thrust cylinder (658, 758), connected in sliding manner inside the first cylinder (601, 701), and has a first end (602b, 702b) fixed to the connecting element (652, 752) and a second end (602a, 702a) configured for sliding inside the thrust cylinder (658, 758) and overlying a chamber (605, 705) comprising lubrication and cooling oil overlying the piston (601b, 701b).

Pumps are provided, more particularly piston type pumps having increased energy efficiency, systems incorporating such piston type pumps, and methods of operating piston type pumps. The pumps are suitable for pumping of oil from an oil well or for pumping other liquids such as ground water, subterranean liquids, brackish water, sea water, waste water, cooling water, gas, coolants, and the like.