US20090194295A1

US20090194295A1 - System, method and apparatus for electrical submersible pump with integrated gas separator

Info

Publication number: US20090194295A1
Application number: US12/025,139
Authority: US
Inventors: Joseph Scott Thompson; Kevin R. Bierig
Original assignee: Baker Hughes Inc
Current assignee: Baker Hughes Holdings LLC
Priority date: 2008-02-04
Filing date: 2008-02-04
Publication date: 2009-08-06

Abstract

A combined gas separator and pump in an electrical submersible pump assembly is disclosed. An integral discharge connector threadingly couples the gas separator and pump. The connector contains discharge ports for the discharge of the separated gas. The pump shaft and gas separator shaft are also coupled. Alternatively, a single pump shaft extends from the pump into the gas separator. In another alternative, the gas separator is completely integrated into the pump housing. The pump is modified by removing the intake of the pump and a sufficient number of pump stages to accommodate the gas separator components. A diverter tube is located in the pump housing and the pump housing is modified to include gas exit ports. All of the gas separator components are located in the modified pump housing, and the original pump intake is reattached at its original location.

Description

BACKGROUND OF THE INVENTION

1. Technical Field
The present invention relates in general to gas separators for electrical submersible pumps and, in particular, to an improved system, method, and apparatus for integrating a gas separator into an electrical submersible pump assembly.
2. Description of the Related Art
A gas separator is used for separating the mixture of gas and liquid at the intake of a pump at the bottom of a well. Currently, gas separators are constructed in a separate housing that bolts to the bottom of the pump. The gas separator also acts as a fluid intake for the pump after the gas has been separated from the liquid stream.
For example, as shown in FIG. 1, a typical gas separator 11 includes an intake 13 at its base (just above seal and motor 14) where all fluid and gas flows into the pump system. It also includes an integral discharge head 15 that has exhaust ports 17 to exhaust the gas out of the system. The gas separator further includes a flow path for the remaining fluid to be directed into the base of the pump 19. When installed, the gas separator attaches to the pump via a flanged, bolted connection 21.

SUMMARY OF THE INVENTION

Embodiments of a system, method, and apparatus for combining a centrifugal gas separator with a pump in an electrical submersible pump (ESP) assembly are disclosed. The invention uses an integral discharge connector to complete the assembly between the gas separator and pump. The base of the pump and discharge head of the gas separator are replaced with a connector that threads into the housing of the pump on one end and into the housing of the gas separator on the other end. The connector contains discharge ports for the discharge of the separated gas. The standard pump shaft is coupled to the standard gas separator shaft using a conventional coupling. The connector contains a bearing for shaft stabilization.
In one type of alternate embodiment, a single, longer pump shaft extends from the pump and is used by both the pump and the gas separator. This design eliminates the need for a stub shaft in the gas separator, and eliminates the shaft coupling.
In another alternate embodiment the gas separator is integrated into the pump housing. A conventional pump for an ESP assembly is converted to have an integral gas separator that requires little modification to the original pump. The pump is retrofitted to allow room for the gas separator internal parts. The pump is modified by removing the intale of the pump, and removing a sufficient number of pump stages to accommodate the gas separator components. A diverter tube is located in the pump housing and holes are drilled in the pump housing for retention pins to prevent rotation of the diverter tube. The pump housing also is modified to include gas exit ports. All of the gas separator components are located in the modified pump housing, and the original pump intake is attached at its original location. This design integrates the gas separator into the housing of the pump, eliminates all connections therebetween, and allows use of a single housing and shaft.
Advantages of this invention over current technology include the elimination of bolted connections, shorter installation lengths, reduced weight, fewer necessary components, and a reduction in overall product cost.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the present invention, taken in conjunction with the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features and advantages of the present invention are attained and can be understood in more detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof that are illustrated in the appended drawings. However, the drawings illustrate only some embodiments of the invention and therefore are not to be considered limiting of its scope as the invention may admit to other equally effective embodiments.

FIG. 1 is a side view of a conventional electrical submersible pump (ESP);

FIG. 2 is a side view of one embodiment of an integrated gas separator and ESP constructed in accordance with the invention;

FIG. 3 is a sectional side view of the ESP of FIG. 2 and is constructed in accordance with the invention;

FIG. 4 is a side view of another embodiment of an integrated gas separator and ESP constructed in accordance with the invention;

FIG. 5 is a sectional side view of the ESP of FIG. 4 and is constructed in accordance with the invention; and

FIG. 6 is a sectional side view of third embodiment of an integrated gas separator and ESP constructed in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 2-6, embodiments of a system, method and apparatus for combining a centrifugal gas separator with a pump in an electrical submersible pump (ESP) assembly are disclosed.
As shown in FIGS. 2 and 3, one embodiment of the invention comprises an ESP assembly 31 having a pump 33 having a pump housing 35. The ESP assembly 31 also includes a centrifugal gas separator 37 having a gas separator housing 39 that, in one embodiment, includes an intake 41, an auger 43, a rotor 45 and a diverter 47. The auger and rotor may be formed as separate components or as a contiguous component. The gas separator also may comprise other types, such as a vortex type having a guide vane. A discharge connector 49 extends between and is threadingly coupled (i.e., rather than bolted) on both ends to the pump housing 35 and the gas separator housing 39. The discharge connector 49 has a plurality of discharge ports 51 coupled to the diverter 47 for discharging gas separated by the centrifugal gas separator 37.
The pump 33 has a pump shaft 53, the centrifugal gas separator 37 has a gas separator shaft 55, and the pump shaft 53 is secured to the gas separator shaft 55 with a coupling 57. The coupling 57 may be located within the discharge connector 49 downstream from the diverter 47. The discharge connector 49 may contain a bearing 59 for stabilization of the pump shaft 53, the coupling 57 and the gas separator shaft 55.
In the embodiment shown, a downstream end 61 of the gas separator shaft 55 is located in the discharge connector 49. The diverter 47 has an inner diameter gas passage 63 in communication with the discharge ports 51 in the discharge connector 49. In addition, an outer diameter liquid passage 65 is located between an outer portion of the diverter 47 and an inner portion of the discharge connector 49. The diverter 47 may be located completely within an axial length of the discharge connector 49.
Another type of ESP assembly 71 is shown in the embodiment of FIGS. 4 and 5. The pump housing 35 has an axis 67 and an upstream end 69. A single, longer pump shaft 75 extends in the axial direction beyond the upstream end 69. The shaft 75 extends through an axially shorter discharge connector 73 and the centrifugal gas separator 37 to a seal section and/or motor 77 depending on the application. In this way the single pump shaft 75 operates the pump 33 and the centrifugal gas separator 37 via motor 77.
The centrifugal or rotary gas separator 37 provides active separation of the gas from the liquid. The fluid intake 41 is at the bottom of the separator 37. In one configuration, fluid is pushed up by the auger 43, separated by the rotor 45 and moved toward the pump 33. The separator 37 spins the heavier fluid to the outer diameter region 65 of the separator housing 39. The lighter fluid (e.g., gas) is conveyed through the inner diameter region 63 near the shaft 55, 75. The lighter fluid is then diverted by the diverter 47 out of the discharge ports 51 in the connector 49 that are located upstream from the first pump stage 36.
Referring now to FIG. 6, another embodiment of an electrical submersible pump assembly 81 is shown. Assembly 81 is similar to the preceding embodiments, but incorporates all working components and features of both the pump and the separator into a single continuous pump housing 83. The pump housing 83 has an axis 85, an upstream end 87, a pump shaft 89 that extends in an axial direction, a plurality of pump stages 91, and a plurality of discharge ports 93 formed through a wall of the pump housing 83.
Thus, the centrifugal gas separator is located completely inside an axial length of the pump housing 83. The components of the separator may include an auger 95 and rotor 97 which are attached or otherwise coupled to the pump shaft 89 for rotation therewith. The pump intake 101 is located adjacent the upstream end 87 of the pump housing 83 upstream from the auger 95 and the rotor 97.
A diverter 99 is located between the rotor 97 and the pump stages 89. The diverter 99 is attached to the discharge ports 93 for discharging gas separated by the centrifugal gas separator through the wall of the pump housing 83. The diverter 99 has an inner diameter gas passage 103 in communication with the discharge ports 93. An outer diameter liquid passage 105 is located between an outer portion of the diverter 99 and an inner portion of the pump housing 83.
The diverter 99 may be mounted to the pump housing 83 (e.g., via pins inserted through holes formed in the pump housing 83) to prevent rotation of the diverter 99 relative to the pump housing 83. The pump shaft 89 extends out of the pump housing 83 beyond the upstream end 87 of the pump housing 83.
One embodiment of the invention also comprises a method of integrating a centrifugal gas separator and a pump. The method may comprise providing an electrical submersible pump (ESP) assembly having a pump with a pump housing, a pump shaft, a plurality of pump stages, and a pump intake; removing the pump intake from the pump housing; removing at least one of the pump stages from the pump housing to accommodate components of a centrifugal gas separator; installing the centrifugal gas separator in the pump housing; forming gas discharge ports in a wall of the pump housing in communication with a gas discharge from the centrifugal gas separator; and reinstalling the pump intake on the pump housing such that the centrifugal gas separator is located completely inside an axial length of the pump housing.
The pump intake may be defined at an original location for the pump intake on the pump housing, and then later securing the pump intake in the original location. The separator components may comprise a diverter, a rotor and an auger on the pump shaft, and then coupling the gas discharge ports in the wall of the pump housing with an inner diameter gas passage in the diverter.
In other embodiments, the diverter may be mounted to the pump housing to prevent rotation of the diverter relative to the pump housing, and the pump shaft may extend out of the pump housing beyond the upstream end of the pump housing. The diverter may be provided with an inner diameter gas passage in communication with the discharge ports, and an outer diameter liquid passage located between an outer portion of the diverter and an inner portion of the pump housing.
While the invention has been shown or described in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.

Claims

1. An electrical submersible pump (ESP) assembly, comprising:

a pump having a pump housing;

a centrifugal gas separator having a gas separator housing with an intake and a diverter; and

a discharge connector extending between and threadingly coupled to the pump housing and the gas separator housing, the discharge connector having a plurality of discharge ports coupled to the diverter for discharging gas separated by the centrifugal gas separator.

2. An ESP assembly according to claim 1, wherein the pump has a pump shaft, the centrifugal gas separator has a gas separator shaft, and the pump shaft is secured to the gas separator shaft with a coupling.

3. An ESP assembly according to claim 2, wherein the discharge connector contains a bearing for stabilization of the pump shaft, the coupling and the gas separator shaft.

4. An ESP assembly according to claim 2, wherein a downstream end of the gas separator shaft is located in the discharge connector, the diverter has an inner diameter gas passage in communication with the discharge ports in the discharge connector, an outer diameter liquid passage is located between an outer portion of the diverter and an inner portion of the discharge connector.

5. An ESP assembly according to claim 2, wherein the coupling is located within the discharge connector downstream from the diverter.

6. An ESP assembly according to claim 1, wherein the diverter is located completely within an axial length of the discharge connector.

7. An ESP assembly according to claim 1, wherein the pump housing has an axis and an upstream end, the pump has a pump shaft that extends in an axial direction beyond the upstream end, through the discharge connector, and into the centrifugal gas separator, such that the pump shaft operates the pump and the centrifugal gas separator.

8. An electrical submersible pump (ESP) assembly, comprising:

a pump having a pump housing with an axis, an upstream end, a pump shaft that extends in an axial direction, a plurality of pump stages, and a plurality of discharge ports formed through a wall of the pump housing;

a centrifugal gas separator located completely inside an axial length of the pump housing and having an auger and a rotor coupled to the pump shaft for rotation therewith, and a diverter located between the rotor and the pump stages, the diverter being coupled to the discharge ports for discharging gas separated by the centrifugal gas separator through the wall of the pump housing; and

a pump intake located adjacent the upstream end of the pump housing upstream from the auger and the rotor.

9. An ESP assembly according to claim 8, wherein the diverter is mounted to the pump housing to prevent rotation of the diverter relative to the pump housing, and the pump shaft extends out of the pump housing beyond the upstream end of the pump housing.

10. An ESP assembly according to claim 8, wherein the diverter has an inner diameter gas passage in communication with the discharge ports, an outer diameter liquid passage is located between an outer portion of the diverter and an inner portion of the pump housing.

11. A method of integrating a centrifugal gas separator and a pump, comprising:

(a) providing an electrical submersible pump (ESP) assembly having a pump with a pump housing, a pump shaft, a plurality of pump stages, and a pump intake;

(b) removing the pump intake from the pump housing;

(c) removing at least one of the pump stages from the pump housing to accommodate components of a centrifugal gas separator;

(d) installing the centrifugal gas separator in the pump housing;

(e) forming gas discharge ports in a wall of the pump housing in communication with a gas discharge from the centrifugal gas separator; and

(f) reinstalling the pump intake on the pump housing such that the centrifugal gas separator is located completely inside an axial length of the pump housing.

12. A method according to claim 11, wherein in step (b) the pump intake defines an original location for the pump intake on the pump housing, and step (g) comprises securing the pump intake in the original location.

13. A method according to claim 11, wherein step (d) comprises attaching a diverter, a rotor and an auger on the pump shaft, and step (e) comprises coupling the gas discharge ports in the wall of the pump housing with an inner diameter gas passage in the diverter.

14. A method according to claim 13, wherein the diverter is mounted to the pump housing to prevent rotation of the diverter relative to the pump housing, and the pump shaft extends out of the pump housing beyond the upstream end of the pump housing.

15. A method according to claim 13, wherein the diverter has an inner diameter gas passage in communication with the discharge ports, an outer diameter liquid passage is located between an outer portion of the diverter and an inner portion of the pump housing.