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.

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.

A counterweighted well pumping unit comprises two or more reversible motors, each of which is directly and operatively connected to a rotatable drive component mounted on a support structure positioned over a wellhead. For each motor, an elongate, flexible drive element is trained over the associated rotatable drive component, with one end of the flexible drive element connected to a counterweight assembly and the other end connected to a pump rod string associated with the wellhead. Actuation of the motors rotates the rotatable drive components, thus causing the drive elements to move the pump rod string and the counterweight assembly in opposite vertical directions. The rotational direction of the drive motors is alternated so as to alternate the directions of vertical movement of the pump rod string and the counterweight. The counterweight assembly may be concentric with or offset from the wellhead.

A counterweighted well pumping unit comprises two or more reversible motors, each of which is directly and operatively connected to a rotatable drive component mounted on a support structure positioned over a wellhead. For each motor, an elongate, flexible drive element is trained over the associated rotatable drive component, with one end of the flexible drive element connected to a counterweight assembly and the other end connected to a pump rod string associated with the wellhead. Actuation of the motors rotates the rotatable drive components, thus causing the drive elements to move the pump rod string and the counterweight assembly in opposite vertical directions. The rotational direction of the drive motors is alternated so as to alternate the directions of vertical movement of the pump rod string and the counterweight. The counterweight assembly may be concentric with or offset from the wellhead.

A sucker rod pumping unit includes a surface beam pivotally coupled to a post assembly mountable on a multi-well pad; two horseheads, each of the two horseheads connected to a particular end of the surface beam, each of the two horseheads including a counterweight to the other of the two horseheads; two sucker rod assemblies, each of the two sucker rod assemblies attached to one of the two horseheads; and one rotary machine driveably coupled to the two sucker rod assemblies through the surface beam.

A pumpjack includes a walking beam pivotally connected to a vertical support for oscillation in a generally vertical plane about a first axis. A first end of the walking beam is connected to a sucker rod string. A carriage is movably mounted to the walking beam to move back-and-forth along a length of a tail end of the walking beam. A pitman arm has a first end pivotally connected to the carriage for rotation about a second axis and a second end pivotally connected to a crank arm. A counterweight is mounted to the crank arm and a hydraulic ram is connected to the carriage to move the carriage back-and-forth along the walking beam and establish reciprocation of the sucker rod string.

A pumpjack includes a walking beam pivotally connected to a vertical support for oscillation in a generally vertical plane about a first axis. A first end of the walking beam is connected to a sucker rod string. A carriage is movably mounted to the walking beam to move back-and-forth along a length of a tail end of the walking beam. A pitman arm has a first end pivotally connected to the carriage for rotation about a second axis and a second end pivotally connected to a crank arm. A counterweight is mounted to the crank arm and a hydraulic ram is connected to the carriage to move the carriage back-and-forth along the walking beam and establish reciprocation of the sucker rod string.

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 long-stroke pumping unit includes a tower; a counterweight assembly movable along the tower; a crown mounted atop the tower; a sprocket supported by the crown and rotatable relative thereto; and a belt. The unit further includes a motor having a stator mounted to the crown and a rotor torsionally connected to the sprocket; and a sensor for detecting position of the counterweight assembly. The pumping unit may include a dynamic control system for controlling a speed of a motor.