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 reservoir fluid from a reservoir into the wellbore at the zone of fluid influx. The pump is coupled to a tubing string extending above the pump, and a packer is coupled to the tubing string proximate to an upper end of the zone of fluid influx and seals an annular space around the tubing string. The method includes operating the pump to produce the reservoir fluid from the wellbore through the tubing string. A pump includes a drive chamber with a drive piston, a production chamber with a production piston coupled to the drive piston, and axially separated traveling valves.

A natural gas compressor can include a pre-staging chamber that couples with a supply line to receive natural gas from the supply line. The compressor can additionally include a first-stage chamber that couples with the supply line to receive natural gas from the supply line. The first-stage chamber can additionally be coupled with the pre-staging chamber to receive from the pre-staging chamber natural gas that has been compressed by the pre-staging chamber. The compressor can also include a second-stage chamber configured to receive natural gas that has been compressed by the first-stage chamber.

A reciprocating pump (10) comprises a first upright leg (12), a second upright leg (14), a first cross-over conduit (18), a second cross-over conduit (18), a lower valve assembly (20) and an upper drive assembly (22). The drive assembly includes plungers (30) which exert alternating downward pumping forces on columns of liquid in the legs (12, 14). The valve assembly is located in a reservoir of water (55) and includes suction openings (80, 64) in the water, which lead into the cross-over conduits (18) and (18), respectively. The valve assembly includes a system of valves and pistons (74, 76) for controlling flow of water into the legs (12, 14) via the cross-over conduits (12, 14) when pumping forces are alternately applied to columns of wafer in the legs (12, 14) wherein water in the legs is raised and lowered in alternating pendulum fashion. Water is drawn into and alternately forced along the cross-over conduits into the legs where the water is pumped from upper ends of the legs (12, 14) via slots (31) defined in the plungers.

The invention relates to a metering pump having a hydraulic drive (12) for supplying a hydraulic fluid under pressure. The metering pump furthermore comprises a housing (2) and an oscillating piston (3), which is accommodated in the housing (2) in such a way that at least a first and a second hydraulic chamber (9-1, 9-2) and a first (6-1) and a second delivery chamber (6-2) are formed, wherein the oscillating piston (3) has at least a first driving surface (10-1) in the first hydraulic chamber (9-1) and at least a second driving surface (10-2) in the second hydraulic chamber (9-2), and the hydraulic chambers (9-1, 9-2) communicate with the hydraulic drive, thus enabling the oscillating piston (3) to be moved backward and forward between a first and a second position by the hydraulic fluid, wherein, during the movement from the first to the second position, the volume of the first delivery chamber (6-1) is enlarged and the volume of the second delivery chamber (6-2) is reduced and, during the movement from the second to the first position, the volume of the second delivery chamber (6-2) is enlarged and the volume of the first delivery chamber (6-1) is reduced. The invention furthermore relates to a metering system for mixing two fluids and a metering system for metering at least one fluid.

A fluid delivery device comprises a hydraulic pump chamber having a hydraulic fluid. A fluid reservoir is coupled to the hydraulic pump chamber and is configured to contain a fluid deliverable to a patient. A first actuator is coupled to the hydraulic pump chamber and is configured to pressurize the hydraulic pump chamber and configured to transfer energy through the hydraulic pump chamber to the fluid reservoir. A second actuator is coupled to the hydraulic pump chamber and is configured to pressurize the hydraulic pump chamber and configured to transfer energy through the hydraulic pump chamber to the fluid reservoir.

A reversing valve for a hydraulic piston pump, including a pilot valve and a main valve. The pilot valve includes a pilot valve seat, a hollow spool and a pull rod. The main valve comprises an upper valve seat, a lower valve seat and a main spool. When the hollow spool is at a lower position, the control flow path communicates with the exhaust fluid flow path, and the main spool is at a lower position, so the power piston is driven to move upwardly by the power fluids provided by the main valve. When the hollow spool is at an upper position, the power piston is driven, by the power fluids provided by the main valve, to set at an upper position, and the power fluids provided by the pilot valve force the power piston to move downwardly.

A fluid delivery device comprises a hydraulic pump chamber having a hydraulic fluid. A fluid reservoir is coupled to the hydraulic pump chamber and is configured to contain a fluid deliverable to a patient. A first actuator is coupled to the hydraulic pump chamber and is configured to pressurize the hydraulic pump chamber and configured to transfer energy through the hydraulic pump chamber to the fluid reservoir. A second actuator is coupled to the hydraulic pump chamber and is configured to pressurize the hydraulic pump chamber and configured to transfer energy through the hydraulic pump chamber to the fluid reservoir.

A natural gas compressor can include a pre-staging chamber that couples with a supply line to receive natural gas from the supply line. The compressor can additionally include a first-stage chamber that couples with the supply line to receive natural gas from the supply line. The first-stage chamber can additionally be coupled with the pre-staging chamber to receive from the pre-staging chamber natural gas that has been compressed by the pre-staging chamber. The compressor can also include a second-stage chamber configured to receive natural gas that has been compressed by the first-stage chamber.

A natural gas compressor can include a pre-staging chamber that couples with a supply line to receive natural gas from the supply line. The compressor can additionally include a first-stage chamber that couples with the supply line to receive natural gas from the supply line. The first-stage chamber can additionally be coupled with the pre-staging chamber to receive from the pre-staging chamber natural gas that has been compressed by the pre-staging chamber. The compressor can also include a second-stage chamber configured to receive natural gas that has been compressed by the first-stage chamber.

The invention relates to a metering pump having a hydraulic drive (12) for supplying a hydraulic fluid under pressure. The metering pump furthermore comprises a housing (2) and an oscillating piston (3), which is accommodated in the housing (2) in such a way that at least a first and a second hydraulic chamber (9-1, 9-2) and a first (6-1) and a second delivery chamber (6-2) are formed, wherein the oscillating piston (3) has at least a first driving surface (10-1) in the first hydraulic chamber (9-1) and at least a second driving surface (10-2) in the second hydraulic chamber (9-2), and the hydraulic chambers (9-1, 9-2) communicate with the hydraulic drive, thus enabling the oscillating piston (3) to be moved backward and forward between a first and a second position by the hydraulic fluid, wherein, during the movement from the first to the second position, the volume of the first delivery chamber (6-1) is enlarged and the volume of the second delivery chamber (6-2) is reduced and, during the movement from the second to the first position, the volume of the second delivery chamber (6-2) is enlarged and the volume of the first delivery chamber (6-1) is reduced. The invention furthermore relates to a metering system for mixing two fluids and a metering system for metering at least one fluid.