Electrically powered motor lubricant pressure compensator for submersible pump motor

Patent metadata

Field	Value
Publication number	US-10669825-B2
Application number	US-201715830140-A
Country	US
Kind code	B2
Filing date	Dec 4, 2017
Priority date	Dec 16, 2016
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

An electrical submersible well pump assembly includes an electrical motor for driving a pump. A pressure compensating chamber contains a dielectric lubricant in fluid communication with an interior of the motor. A movable pressure compensating element has a first side in contact with the lubricant in the chamber. Movement of the element relative to the chamber causes a change in volume of the chamber. An electrical drive mechanism is connected with and moves the element. A controller senses a pressure difference between the lubricant pressure and the well fluid pressure and operates the drive mechanism in response. The element may be a piston, a bellows or telescoping tubes.

First claim

The invention claimed is:

1. An electrical submersible pump assembly for pumping well fluid from a well, comprising:
an electrical pump motor for driving a pump;
a pressure compensating chamber containing a dielectric lubricant that is in fluid communication with an interior of the pump motor;
a movable pressure compensating element having a first side in contact with the lubricant in the chamber, wherein movement of the element relative to the chamber causes a change in volume of the chamber;
an electrical drive mechanism connected with the element for moving the element relative to the chamber; and
a controller that operates the drive mechanism in response to a difference between a pressure of the lubricant in the chamber and a pressure of well fluid on an exterior of the pump motor.

2. The assembly according to claim 1 , wherein:
the element comprises a piston that is in sliding engagement with a side wall of the chamber.

3. The assembly according to claim 1 , wherein the element comprises:
a piston that slides in sealing engagement against a side wall of the chamber; and wherein the assembly further comprises:
a spring compressed against a second side of the piston.

4. The assembly according to claim 1 , wherein:
the chamber is within a housing at a lower end of the pump motor;
the element comprises a piston that slides in the housing and separates lubricant in an upper portion of the housing from a lower portion of the housing; wherein the assembly further comprises:
a spring in the lower portion of the housing and compressed against a lower side of the piston; and
wherein the lower portion of the housing is filled with a pressurized gas that exerts a force against the lower side of the piston.

5. The assembly according to claim 1 , wherein:
the element comprises a bellows having an interior open to well fluid, the first side of the element comprising an exterior of the bellows, which is immersed in the lubricant in the chamber; and
the drive mechanism couples to a first end of the bellows for moving the first end of the bellows relative to a second end of the bellows.

6. The assembly according to claim 1 , further comprising bias means for biasing the element toward a smaller chamber volume position.

7. The assembly according to claim 1 , wherein:
the chamber contains a pressurized gas that acts against a second side of the element.

8. The assembly according to claim 1 , wherein the element comprises:
a first piston that is stroked by the drive mechanism between a larger chamber volume position and a smaller chamber volume position; and wherein the assembly further comprises:
a second piston having a first side facing the first piston and a second side;
a well fluid port in the chamber for admitting well fluid from an exterior of the pump motor to the second side of the second piston; and
a protective barrier fluid located between and in contact with the first and second pistons.

9. The assembly according to claim 1 , wherein the drive mechanism comprises:
a servo motor shaft;
a servo motor that rotates the shaft;
a rotary to linear translator that translates rotation of the servo motor shaft to linear movement; and wherein
the element is coupled to the linear translator for linear movement therewith.

10. The assembly according to claim 1 , wherein:
the element comprises a sealed enclosure within the chamber, the enclosure having first and second components that are moveable relative to each other, the enclosure having an exterior that comprises the first side of the element and is immersed in the lubricant in the chamber; and
the drive mechanism is coupled to the first component for moving first component relative to the second component to change a volume of the enclosure.

11. An electrical submersible pump assembly for pumping well fluid from a well, comprising:
an electrical pump motor for driving a pump;
a pressure compensating chamber containing a dielectric lubricant that is in fluid communication with an interior of the pump motor;
a movable pressure compensating element within the chamber, wherein movement of the element relative to the chamber causes a change in volume of the chamber;
an external pressure sensor that senses a pressure of well fluid on an exterior of the pump motor;
an internal pressure sensor that senses a pressure of the lubricant in the chamber; and
an electrical drive mechanism coupled to the element for moving the element relative to the chamber in response to signals from the internal and external pressure sensors.

12. The assembly according to claim 11 , wherein:
the element comprises a piston coupled to the drive mechanism.

13. The assembly according to claim 11 , wherein:
the element comprises a bellows having a movable end and a fixed end; and
the movable end is coupled to the drive mechanism.

14. The assembly according to claim 11 , wherein:
the element comprises first and second telescoping tubes that sealingly engage each other; and
the first telescoping tube is coupled to the drive mechanism.

15. The assembly according to claim 11 , further comprising:
a spring compressed against the element to urge the element toward a smaller chamber volume position.

16. The assembly according to claim 11 , further comprising:
a pressurized gas acting against the element to urge the element toward a smaller chamber volume position.

17. The assembly according to claim 11 , wherein:
the element has a first side in contact with the lubricant in the chamber; and the assembly further comprises:
a well fluid entry port within the chamber for admitting well fluid into the chamber into contact with a second side of the element.

18. An electrical submersible pump assembly for pumping well fluid from a well, comprising:
a pump;
an electrical pump motor operatively coupled to the pump;
a pressure compensator housing at a lower end of the pump motor;
a pressure compensating element within the housing;
a dielectric lubricant in the housing in contact with a first side of the element, the first side defining a lubricant chamber within the housing, the dielectric lubricant in the lubricant chamber being in fluid communication with an interior of the pump motor;
an electrical drive mechanism in the housing coupled with the element for moving at least a portion of the element relative to the housing to vary a volume of the lubricant chamber; and
a controller that operates the drive mechanism in response to a difference between a pressure of the lubricant in the lubricant chamber and a pressure of well fluid on an exterior of the pump motor.

19. The assembly according to claim 18 , wherein:
the element comprises a piston that is in sealing and sliding engagement with a side wall of the housing.

20. The assembly according to claim 18 , wherein:
the element comprises a bellows having a movable end coupled to the drive mechanism and a fixed end fixed to the housing;
the first side of the element comprises an exterior surface of the bellows; and
the housing has a well fluid port for communicating well fluid from the exterior of the pump motor to an interior of the bellows.

Assignees

• Baker Hughes
• Baker Hughes A Ge Co Llc

Inventors

• Clingman James Christopher
• Semple Ryan P

Classifications

• F04D13/086

  the pump and drive motor are both submerged · CPC title

• F04D13/10

  adapted for use in mining bore holes · CPC title

• E21B4/003

  Bearing, sealing, lubricating details (for roller bits E21B10/22) · CPC title

• E21B43/128 Primary

  Adaptation of pump systems with down-hole electric drives · CPC title

• H02K2205/09

  Machines characterised by drain passages or by venting, breathing or pressure compensating means · CPC title