Open ended inverted shroud with dip tube for submersible pump

Patent metadata

Field	Value
Publication number	US-9638014-B2
Application number	US-201313972599-A
Country	US
Kind code	B2
Filing date	Aug 21, 2013
Priority date	Aug 21, 2013
Publication date	May 2, 2017
Grant date	May 2, 2017

Abstract

A well pump assembly includes rotary pump and a submersible motor. A shroud surrounds the pump intake and the motor. The shroud has an open upper end in fluid communication with the pump intake for drawing well fluid along an upper flow path down the shroud into the pump intake. A dip tube is secured to and extends downward from a junction with a lower end of the shroud. The dip tube is in fluid communication with the pump intake and has an open lower end for drawing well fluid along a lower flow path up the dip tube to the pump intake. The upper flow path has a minimum flow area that is smaller than a minimum flow area of the lower flow path. The dip tube has a smaller outer diameter than an outer diameter of the shroud.

First claim

The invention claimed is:

1. A well pump assembly, comprising:
a rotary pump having a pump intake and a discharge above the pump intake for connection to a string of production tubing;
a submersible motor operatively engaged with the pump below the pump for driving the pump;
a shroud surrounding the pump intake and the motor, the shroud having an open upper end in fluid communication with the pump intake for drawing well fluid along an upper flow path down the shroud into the pump intake;
a dip tube secured to and extending downward from a junction with a lower end of the shroud, the dip tube being in fluid communication with the pump intake and having an open lower end for drawing well fluid along a lower flow path up the dip tube to the pump intake; and
wherein the upper flow path has a minimum flow area that is smaller than a minimum flow area of the lower flow path.

2. The assembly according to claim 1 , wherein the dip tube has a smaller outer diameter than an outer diameter of the shroud.

3. The assembly according to claim 1 , further comprising:
a fluid restricting device within the shroud above the pump to retard well fluid flow into the shroud; wherein
the minimum flow area of the upper flow path is located in the fluid restricting device and is less than a flow area of the upper flow path in the shroud between the fluid restricting device and the pump intake.

4. The assembly according to claim 1 , wherein the dip tube has an outer diameter that is in the range from 50% to 65% the outer diameter of the shroud.

5. The assembly according to claim 1 , wherein the rotary pump comprises a centrifugal pump.

6. The assembly according to claim 1 , further comprising:
a gas anchor sleeve surrounding a lower portion of the dip tube, the gas anchor sleeve having a closed lower end below the open lower end of the dip tube, and the gas anchor sleeve having an open upper end, requiring well fluid flowing up around the gas anchor sleeve along the lower flow path to flow down between the gas anchor sleeve and the dip tube to reach the open lower end of the dip tube.

7. The assembly according to claim 1 , further comprising:
a recirculation tube extending downward within the shroud from a portion of the pump to a point below the motor and above the dip tube, the recirculation tube diverting a portion of the well fluid being pumped by the pump to below the motor.

8. The assembly according to claim 1 , further comprising:
a movable flow restricting device within the shroud above the pump to enhance well fluid flow up the dip tube, the movable flow restricting device having a first position admitting downward flow of well fluid along the upper flow path in the shroud and being movable to a second position retarding upward flow of well fluid in the shroud.

9. A well pump assembly, comprising:
a rotary pump having a pump intake and a discharge above the pump intake for connection to a string of production tubing;
a submersible motor operatively engaged with the pump below the pump for driving the pump;
a shroud surrounding the pump intake and the motor and adapted to be supported by the string of tubing, the shroud having an open upper end for drawing well fluid down and upper portion of the shroud into the pump intake;
a dip tube secured to and extending downward from a junction with a lower end of the shroud, the junction being below the motor, the dip tube having an open lower end and being in fluid communication with the pump intake for drawing well fluid up the shroud to the pump intake; and
wherein the dip tube has an outer diameter that is less than an outer diameter of the shroud.

10. The assembly according to claim 9 , further comprising:
a gas anchor sleeve surrounding a lower portion of the dip tube and being supported by the dip tube, the gas anchor sleeve having a closed lower end below the open lower end of the dip tube and an open upper end, thereby causing well fluid flowing into the dip tube to flow down the open upper end of the gas anchor sleeve.

11. The assembly according to claim 9 , further comprising:
a fluid restricting device within the shroud above the pump to retard well fluid flow into the shroud; wherein
the fluid restricting device has a flow area that is less than a flow area in the shroud between the fluid restricting device and the pump intake.

12. The assembly according to claim 9 , wherein a minimum flow area along an upper flow path from the upper end of the shroud to the pump intake is less than a minimum flow area along a lower flow path up the dip tube to the pump intake.

13. The assembly according to claim 9 , further comprising:
a pivotal flow restricting device within the shroud above the pump to enhance well fluid flow up the dip tube, the pivotal flow restricting device having a first position admitting downward flow of well fluid in the shroud and being movable to a second position retarding upward flow of well fluid in the shroud in response to a greater flow pressure of well fluid below the pivotal flow restricting device than above.

14. The assembly according to claim 9 , further comprising:
a recirculation tube extending downward within the shroud, the recirculation tube having an open lower end above the junction of the shroud with the dip tube, the recirculation tube diverting a portion of the well fluid being pumped by the pump to below the motor.

15. The assembly according to claim 9 , wherein the dip tube has an outer diameter that is in the range from 50% to 65% the outer diameter of the shroud.

16. A method of producing a well having well fluid containing liquid and gas, comprising:
securing a dip tube to a lower end of a shroud, the dip tube having an open lower end and the shroud having an open upper end;
positioning a pump intake of a pump inside the shroud above the dip tube;
providing a discharge of the pump above the pump intake for a connection to a string of production tubing;
providing a submersible motor operatively engaged with the pump below the pump;
securing the shroud to a string of tubing and lowering the pump and shroud into a well; and
operating the pump, causing well fluid to flow into the open lower end of the dip tube and at the same time into the open upper end of the shroud.

17. The method according to claim 16 , wherein the well has a casing containing perforations, and the method further comprises:
placing the shroud with some of the perforations below the open upper end of the shroud and some of the perforations above the open lower end of the dip tube.

18. The method according to claim 16 , further comprising providing a minimum flow area in the shroud above the pump intake that is less than a minimum flow area in the dip tube.

19. The method according to claim 16 , further comprising:
mounting a gas anchor sleeve around the dip tube, the gas anchor sleeve having a closed lower end below the open lower end of the dip tube, the gas anchor sleeve having an open upper end above the open lower end of the dip tube; and
causing well fluid that is flowing upward toward the dip tube to flow up around the gas anchor sleeve, then downward to the open lower end of the dip tube to facilitate separation of gas from liquid in the well fluid.

Assignees

• Baker Hughes Inc

Inventors

• Reid Leslie C

Classifications

• F04D29/406

  especially adapted for liquid pumps · CPC title

• F04D1/06

  Multi-stage pumps (F04D1/02, F04D13/10 take precedence) · CPC title

• E21B43/128 Primary

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

• F04D13/10

  adapted for use in mining bore holes · CPC title