A lift apparatus and method for driving a downhole reciprocating pump is disclosed. The apparatus includes a hydraulic cylinder having a piston and a hydraulic fluid port, the piston being coupled to a rod for driving the reciprocating pump, the piston being moveable between first and second ends of the cylinder in response to a flow of hydraulic fluid through the hydraulic fluid port. The apparatus also includes a variable displacement hydraulic pump coupled to receive a substantially constant rotational drive from a prime mover for operating the hydraulic pump, the hydraulic pump having an outlet and being responsive to a displacement control signal to draw hydraulic fluid from a reservoir and to produce a controlled flow of hydraulic fluid at the outlet. The apparatus also includes a hydraulic fluid line connected to deliver hydraulic fluid from the outlet of the hydraulic pump through the hydraulic fluid port to the cylinder for causing the piston to move through an upstroke away from the first end and toward the second end of the cylinder. The apparatus further includes a valve connected between the hydraulic fluid port and the reservoir, the valve being responsive to a valve control signal for controlling discharge of hydraulic fluid from the hydraulic fluid port of the cylinder back to the reservoir to facilitate movement of the piston through a downstroke away from the second end toward the first end of the cylinder. The valve is operable to prevent flow of hydraulic fluid through the valve during the upstroke and the hydraulic pump is operable to prevent flow of hydraulic fluid back into the outlet of the hydraulic pump during the downstroke.

A method of producing fluid from a wellbore includes operating a pump located proximate to a zone of fluid influx in the wellbore to draw a fluid from a reservoir into the wellbore at the zone of fluid influx. A first section of a tubing string is coupled to, and extends above, the pump, and a second section of the tubing string is coupled to, and extends below, the pump. A packer seals a first annular space around the first section of the tubing string. The method further includes operating the pump to move the fluid from the second section of the tubing string and into the first section of the tubing string.

An artificial lift system may include a rodless hydraulic pump actuator including an actuator housing assembly, an actuator piston assembly supported for reciprocal translation stroke movement relative to the actuator piston assembly, an actuator piston assembly production fluid passage extending through the actuator piston assembly, and a tubular coupling below the actuator housing assembly having a coupling flow passage to pass production fluid into the actuator piston assembly production fluid passage.

An artificial lift system may include a rodless hydraulic pump actuator including an actuator housing assembly, an actuator piston assembly supported for reciprocal translation stroke movement relative to the actuator piston assembly, an actuator piston assembly production fluid passage extending through the actuator piston assembly, and a tubular coupling below the actuator housing assembly having a coupling flow passage to pass production fluid into the actuator piston assembly production fluid passage.

A hydrocarbon wellbore production apparatus includes a tailpipe and a control valve connected with the tailpipe. The tailpipe has a fluid inlet receiving well fluids entering the casing from a formation, and a fluid outlet above the fluid inlet to deliver well liquid to a connected pump inlet. The control valve is operable to (i) open when a lower fluid pressure below the flow control valve exceeds an upper fluid pressure above the flow control valve to allow upward flow through the flow control valve, (ii) close when the upper fluid pressure exceeds the lower fluid pressure by an amount which does not exceed a prescribed pressure limit value to hold fluid in the apparatus above the flow control valve, and (iii) open when the upper fluid pressure exceeds the lower fluid pressure by an amount which exceeds the pressure limit value to release excess fluid back down the tailpipe.

An electric submersible pump (ESP) electric motor. The ESP electric motor comprises a housing; a stator retained within the housing; a drive shaft; and an at least one rotor mechanically coupled to the drive shaft and located concentric with and inside of the stator, wherein an inside surface of the stator defines a groove extending from an upper end to a lower end of the stator, an outside surface of the at least one rotor defines a groove extending from an upper end to a lower end of the at least one rotor, an inside surface of the at least one rotor defines a groove extending from an upper end to a lower end of the at least one rotor, or an outside surface of the drive shaft defines a groove extending from below an male splines at an upper end to a lower end of the drive shaft.

An electric submersible pump (ESP) electric motor. The ESP electric motor comprises a housing; a stator retained within the housing; a drive shaft; and an at least one rotor mechanically coupled to the drive shaft and located concentric with and inside of the stator, wherein an inside surface of the stator defines a groove extending from an upper end to a lower end of the stator, an outside surface of the at least one rotor defines a groove extending from an upper end to a lower end of the at least one rotor, an inside surface of the at least one rotor defines a groove extending from an upper end to a lower end of the at least one rotor, or an outside surface of the drive shaft defines a groove extending from below an male splines at an upper end to a lower end of the drive shaft.

A fluid-driven linear motor comprises a cylinder (5), a piston (4) and a piston rod (3) connected to the piston (4), wherein the two sides of the piston (4) in the cylinder (5) are alternatively supplied with fluid from a slide valve arrangement, the slide valve arrangement including a slide (9) accommodated in a chamber and which is shifted between its end positions controlled by a pilot rod (22) coaxially mounted in a through bore (12) in the slide (9). The pilot rod (22) is adapted to alternately set the through bore (12) in fluid connection with the ends of the slide (9) when the piston (4) is located in its end positions. The pilot rod (22.) is provided with an extension rod (204) adapted to slide inside a bore (203) inside said piston (5) and said piston rod (3), so that the stroke length of the linear motor can be extended. Moreover, a pressure chamber (209) is provided at the distal end of the pilot rod (22), said pressure chamber (209) being adapted to hold on the pilot rod (22) with a holding force when in its end positions until mechanical forces from the piston overcome said holding force.

The present disclosure relates to a pump system having a pneumatically actuated fluid pump, which makes use of standard cycle counter to assist in determining when an air supply control valve is stuck in an open state after a fluid discharge cycle has completed. The system includes an electronic controller which receives signals from the cycle counter. The signals indicate a position of a sensing element inside the cycle counter. The electronic controller uses the signals to determine if the sensing element is still experiencing a pressurized airflow after a fluid discharge cycle has completed and the air supply control valve has been commanded to close.

A pumping system pumps material or fluid downhole, for example, to perform a stimulation operation. The pumping system comprises a hydraulic pump coupled to an intensifier. The intensifier comprises a piston which allows for a small footprint as compared to an intensifier with a plunger. The hydraulic cylinder of the intensifier is protected from the corrosive, erosive and abrasive effects of the material or fluid to be pumped by one or more seals. Using the intensifier that includes a piston provides for a greater reliability of the overall pumping system as fewer strokes are required and a compact pumping system as the stroke length of the intensifier with a piston is less than the stroke length required for a plunger.