A hydraulic pumping system can include a hydraulic actuator with a magnet that displaces with a piston, and a sensor that continuously detects a position of the magnet. A ferromagnetic wall of the hydraulic actuator is positioned between the magnet and the sensor. A hydraulic pumping method can include incrementally lowering a lower stroke extent of a rod string reciprocation over multiple reciprocation cycles of the rod string, and automatically varying the lower stroke extent or an upper stroke extent of the rod string reciprocation, in response to a measured vibration. Another hydraulic pumping method can include solving a wave equation in the rod string, and automatically varying a reciprocation speed of the rod string in response to a change in work performed during reciprocation cycles of the hydraulic actuator or a change in detected force versus displacement in different reciprocation cycles of the hydraulic actuator.

A hydraulic pumping system can include a hydraulic actuator with a magnet that displaces with a piston, and a sensor that continuously detects a position of the magnet. A ferromagnetic wall of the hydraulic actuator is positioned between the magnet and the sensor. A hydraulic pumping method can include incrementally lowering a lower stroke extent of a rod string reciprocation over multiple reciprocation cycles of the rod string, and automatically varying the lower stroke extent or an upper stroke extent of the rod string reciprocation, in response to a measured vibration. Another hydraulic pumping method can include solving a wave equation in the rod string, and automatically varying a reciprocation speed of the rod string in response to a change in work performed during reciprocation cycles of the hydraulic actuator or a change in detected force versus displacement in different reciprocation cycles of the hydraulic actuator.

A well pump assembly has a tubular receptacle for attachment to a lower end of a string of production tubing. A docking station mounts to the receptacle, the docking station having a lower well fluid conduit for receiving well fluid from the well, a lower orientation guide, and a lower hydraulic connector. A hydraulic line extends alongside the receptacle and is in fluid communication with the lower hydraulic connector for supplying hydraulic fluid. A hydraulically actuated pump is configured to be lowered into and retrieved from the receptacle. A guide member on a lower end of the pump has an upper orientation guide, and an upper hydraulic connector in fluid communication with the pump, and an upper well fluid conduit leading to an intake of the pump.

A fluid-driven linear motor comprises a cylinder, a piston, and a piston rod connected to the piston. Two sides of the piston in the cylinder are alternately supplied with fluid from a slide valve arrangement. The slide valve arrangement includes a slide and a pilot rod adapted to alternately set a through-bore of a slide in fluid connection with the ends of the slide when the piston is located in its end positions. The pilot rod is provided with an extension rod adapted to move inside a bore of the piston and the piston rod, so that the stroke length of the linear motor can be extended. A pressure chamber is provided at the distal end of the pilot rod. The pressure chamber is adapted to hold the pilot rod with a holding force when in its end positions until mechanical forces from the piston overcome said holding force.

A fluid-driven linear motor comprises a cylinder, a piston, and a piston rod connected to the piston. Two sides of the piston in the cylinder are alternately supplied with fluid from a slide valve arrangement. The slide valve arrangement includes a slide and a pilot rod adapted to alternately set a through-bore of a slide in fluid connection with the ends of the slide when the piston is located in its end positions. The pilot rod is provided with an extension rod adapted to move inside a bore of the piston and the piston rod, so that the stroke length of the linear motor can be extended. A pressure chamber is provided at the distal end of the pilot rod. The pressure chamber is adapted to hold the pilot rod with a holding force when in its end positions until mechanical forces from the piston overcome said holding force.

A downhole injection system in selective communication with a wellhead assembly and a wellbore, the downhole injection system including a pumping chamber in selective communication with the wellhead assembly, the pumping chamber defining a wellhead pressure portion defining a wellhead pressure inlet in selective communication with the wellhead assembly and a wellhead pressure outlet in selective communication with the wellhead assembly, where the wellhead pressure portion is maintained at a wellhead pressure, and a chemical portion in selective communication with the wellbore, and a movable plate positioned within the pumping chamber, where the chemical portion is separated from the wellhead pressure portion by the movable plate.

A hydraulic pumping system can include a hydraulic actuator with a magnet that displaces with a piston, and a sensor that continuously detects a position of the magnet. A ferromagnetic wall of the hydraulic actuator is positioned between the magnet and the sensor. A hydraulic pumping method can include incrementally lowering a lower stroke extent of a rod string reciprocation over multiple reciprocation cycles of the rod string, and automatically varying the lower stroke extent or an upper stroke extent of the rod string reciprocation, in response to a measured vibration. Another hydraulic pumping method can include solving a wave equation in the rod string, and automatically varying a reciprocation speed of the rod string in response to a change in work performed during reciprocation cycles of the hydraulic actuator or a change in detected force versus displacement in different reciprocation cycles of the hydraulic actuator.

A hydraulic pumping system can include a hydraulic actuator with a magnet that displaces with a piston, and a sensor that continuously detects a position of the magnet. A ferromagnetic wall of the hydraulic actuator is positioned between the magnet and the sensor. A hydraulic pumping method can include incrementally lowering a lower stroke extent of a rod string reciprocation over multiple reciprocation cycles of the rod string, and automatically varying the lower stroke extent or an upper stroke extent of the rod string reciprocation, in response to a measured vibration. Another hydraulic pumping method can include solving a wave equation in the rod string, and automatically varying a reciprocation speed of the rod string in response to a change in work performed during reciprocation cycles of the hydraulic actuator or a change in detected force versus displacement in different reciprocation cycles of the hydraulic actuator.

Downhole well pump assembly (1) having first and second pump units (7a, 7b) with first and second bellows (31) connected to inlet and outlet check valves. A drive fluid assembly (5) with first and second hydraulic drive lines (9a, 9b) communicates with the bellows. Hydraulic fluid is provided to the first and second hydraulic drive lines. A drive fluid distribution valve (11) is arranged between a drive pump (17) and the drive lines. It has a drive fluid inlet and outlet (113, 115), and first and second drive ports. The distribution valve (11) interchanges between a first mode, where the drive fluid inlet communicates with the first drive port and the drive fluid outlet (115) communicates with the second drive port; and a second mode, wherein the drive fluid inlet communicates with the second drive port, and the drive fluid outlet communicates with the first drive port.

Downhole well pump assembly (1) having first and second pump units (7a, 7b) with first and second bellows (31) connected to inlet and outlet check valves. A drive fluid assembly (5) with first and second hydraulic drive lines (9a, 9b) communicates with the bellows. Hydraulic fluid is provided to the first and second hydraulic drive lines. A drive fluid distribution valve (11) is arranged between a drive pump (17) and the drive lines. It has a drive fluid inlet and outlet (113, 115), and first and second drive ports. The distribution valve (11) interchanges between a first mode, where the drive fluid inlet communicates with the first drive port and the drive fluid outlet (115) communicates with the second drive port; and a second mode, wherein the drive fluid inlet communicates with the second drive port, and the drive fluid outlet communicates with the first drive port.