Abstract: An artificial lift system can include an actuator operable to reciprocate a rod string in the well, the actuator including a piston reciprocably disposed in a cylinder, and a piston rod connected to the piston, and a rod rotator that continuously rotates the piston rod relative to the cylinder as the piston displaces in a longitudinal direction relative to the cylinder. A method of rotating a rod string can include connecting the rod string to a piston rod of an actuator, longitudinally reciprocating the piston rod relative to a cylinder of the actuator and a mandrel of a rod rotator, and rotating the piston rod relative to the mandrel in response to the reciprocating, the mandrel being disposed at least partially within the piston rod during the rotating. A rod rotator can include a mandrel having a helical external profile configured to attach to a cylinder of a hydraulic actuator, an internal profile complementarily shaped relative to the external profile, and a one-way clutch.

Abstract: An artificial lift system can include an actuator operable to reciprocate a rod string in the well, the actuator including a piston reciprocably disposed in a cylinder, and a piston rod connected to the piston, and a rod rotator that continuously rotates the piston rod relative to the cylinder as the piston displaces in a longitudinal direction relative to the cylinder. A method of rotating a rod string can include connecting the rod string to a piston rod of an actuator, longitudinally reciprocating the piston rod relative to a cylinder of the actuator and a mandrel of a rod rotator, and rotating the piston rod relative to the mandrel in response to the reciprocating, the mandrel being disposed at least partially within the piston rod during the rotating. A rod rotator can include a mandrel having a helical external profile configured to attached to a cylinder of a hydraulic actuator, an internal profile complementarily shaped relative to the external profile, and a one-way clutch.

Abstract: Three-phase separation is achieved downhole in a production well by forming an oil/liquid separation zone in the well between two packers which are positioned between producing and disposal zones. Gas is permitted to separate above the top packer. A pump is used to pump an oil/water mixture from above the top packer into the separation zone. Adequate residence time is permitted in the separation zone to achieve the separation. A check valve in the bottom packer is used to provide pressure to raise the oil to the wellhead. A control valve at the wellhead is used to control pressure in the separation zone and the relative sizes of the streams issuing therefrom.

Abstract: Three-phase separation is achieved downhole in a production well by forming an oil/liquid separation zone in the well between two packers which are positioned between producing and disposal zones. Gas is permitted to separate above the top packer. A pump is used to pump an oil/water mixture from above the top packer into the separation zone. Adequate residence time is permitted in the separation zone to achieve the separation. A check valve in the bottom packer is used to provide pressure to raise the oil to the wellhead. A control valve at the wellhead is used to control pressure in the separation zone and the relative sizes of the streams issuing therefrom.

Abstract: Three-phase separation is achieved downhole in a production well by forming an oil/liquid separation zone in the well between two packers which are positioned between producing and disposal zones. Gas is permitted to separate above the top packer. A pump is used to pump an oil/water mixture from above the top packer into the separation zone. Adequate residence time is permitted in the separation zone to achieve the separation. A check valve in the bottom packer is used to provide pressure to raise the oil to the wellhead. A control valve at the wellhead is used to control pressure in the separation zone and the relative sizes of the streams issuing therefrom.

Abstract: Three-phase separation is achieved downhole in a production well by forming an oil/liquid separation zone in the well between two packers which are positioned between producing and disposal zones. Gas is permitted to separate above the top packer. A pump is used to pump an oil/water mixture from above the top packer into the separation zone. Adequate residence time is permitted in the separation zone to achieve the separation. A check valve in the bottom packer is used to provide pressure to raise the oil to the wellhead. A control valve at the wellhead is used to control pressure in the separation zone and the relative sizes of the streams issuing therefrom.

Abstract: A hydraulic pump includes a hydraulic cylinder assembly comprising a cylinder sealed by an upper head and a lower head and carrying a piston which divides the hydraulic cylinder assembly into an upper chamber and a lower chamber. A load is connected to the piston and urges it toward the lower head. A conduit connects a reversible hydraulic pump assembly in fluid flow communication with a pressurized supply of hydraulic fluid and the lower chamber for counterbalancing the load. A control system is operably associated with the reversible hydraulic pump assembly to cause hydraulic fluid to flow back and forth between the lower chamber of the hydraulic cylinder assembly and the pressurized supply of hydraulic fluid. A system is also provided to counteract leakage in the pump by adding hydraulic fluid makeup on an as needed and controlled basis.

Abstract: A hydraulic pump includes a hydraulic cylinder assembly comprising a cylinder sealed by an upper head and a lower head and carrying a piston which divides the hydraulic cylinder assembly into an upper chamber and a lower chamber. A load is connected to the piston and urges it toward the lower head. A conduit connects a reversible hydraulic pump assembly in fluid flow communication with a pressurized supply of hydraulic fluid and the lower chamber for counterbalancing the load. A control system is operably associated with the reversible hydraulic pump assembly to cause hydraulic fluid to flow back and forth between the lower chamber of the hydraulic cylinder assembly and the pressurized supply of hydraulic fluid. A system is also provided to counteract leakage in the pump by adding hydraulic fluid makeup on an as needed and controlled basis.

Abstract: A hydraulic pump includes a hydraulic cylinder assembly comprising a cylinder sealed by an upper head and a lower head and carrying a piston which divides the hydraulic cylinder assembly into an upper chamber and a lower chamber. A load is connected to the piston and urges it toward the lower head. A conduit connects a reversible hydraulic pump assembly in fluid flow communication with a pressurized supply of hydraulic fluid and the lower chamber for counterbalancing the load. A control system is operably associated with the reversible hydraulic pump assembly to cause hydraulic fluid to flow back and forth between the lower chamber of the hydraulic cylinder assembly and the pressurized supply of hydraulic fluid. A system is also provided to counteract leakage in the pump by adding hydraulic fluid makeup on an as needed and controlled basis.

Abstract: Disclosed is an apparatus comprising a hydraulic cylinder assembly, a load connected to the cylinder, a reversible hydraulic pump assembly, a pressurized supply of hydraulic fluid, first and second conduits for hydraulic fluid, and a control system. The hydraulic cylinder assembly comprises a cylinder sealed by an upper head and a lower head and carrying a piston which divides the hydraulic cylinder assembly into an upper chamber and a lower chamber. The load is connected to the piston and urges it toward the lower head. The first conduit for hydraulic fluid connects the reversible hydraulic pump assembly in fluid flow communication with the lower chamber of the hydraulic cylinder assembly. The second conduit for hydraulic fluid connects the reversible hydraulic pump assembly in fluid flow communication with the pressurized supply of hydraulic fluid.

Abstract: Disclosed is an apparatus comprising a hydraulic cylinder assembly, a load connected to the cylinder, a reversible hydraulic pump assembly, a pressurized supply of hydraulic fluid, first and second conduits for hydraulic fluid, and a control system. The hydraulic cylinder assembly comprises a cylinder sealed by an upper head and a lower head and carrying a piston which divides the hydraulic cylinder assembly into an upper chamber and a lower chamber. The load is connected to the piston and urges it toward the lower head. The first conduit for hydraulic fluid connects the reversible hydraulic pump assembly in fluid flow communication with the lower chamber of the hydraulic cylinder assembly. The second conduit for hydraulic fluid connects the reversible hydraulic pump assembly in fluid flow communication with the pressurized supply of hydraulic fluid.