US20190309755A1

US20190309755A1 - Inverted electrical submersible pump and pumping system

Info

Publication number: US20190309755A1
Application number: US15/946,981
Authority: US
Inventors: Woon Yung Lee; Ying Xue
Original assignee: Alkhorayef Petroleum Co Ltd
Current assignee: Alkhorayef Petroleum Co Ltd
Priority date: 2018-04-06
Filing date: 2018-04-06
Publication date: 2019-10-10

Abstract

An electrical submersible pump for use in an electrical submersible pumping (ESP) system includes one or more pump stages, a thrust chamber having a thrust bearing for countering a thrust force generated by the one or more pump stages, and a unitary housing which encloses the pump stages and the thrust chamber so that the thrust mechanism and the pump stages are housed together.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A COMPACT DISK APPENDIX

Not applicable.

BACKGROUND

1. Field

The following description relates to an inverted electrical submersible pump (ESP) system having a pump with an integrated thrust chamber. In an example, the thrust chamber is integrated into the pump of the ESP system so that a separate thrust mechanism and lower motor protector are not necessary. That is, the pump of the inverted system may be attached directly underneath the motor.

2. Description of Related Art

ESP systems typically include multiple pumping stages to generate enough discharge pressure. Each stage includes an impeller and a diffuser. Every impeller creates a thrust force towards the inlet direction, usually downwards in conventional configurations. This thrust force is called the downthrust of the ESP system. If this thrust force is not handled properly, it will wear out the impeller with friction and result in failure of the pump.
Referring to FIG. 1, a conventional ESP configuration 10 includes an intake unit 50 and a seal section 40 installed below a pump 20 and above a motor 30. The thrust load is transferred through a shaft and coupling between the pump 20 and the seal section 40. The seal section 40 has a bearing system filled with a clean lubrication oil. The bearing system has a rotating runner attached to the shaft of the seal section 40 and a bearing pad which is a nonrotating part. This bearing system can handle the accumulated thrust forces transferred along the shaft from the multiple pump stages.
Referring to FIG. 2, in a conventional inverted ESP system 100, the position of the pump 120 and the seal section 150 are switched. A power connector 190, an upper motor protector 195, and a motor 130 are all located at the upper part of the ESP system 100. The pump 120 is located at the lower part of the ESP system 100. The motor seal 140 with bearing system 170 are located above the pump 120 in a lower motor protector 150. The bearing system 170 is located in a sealed section above the pump 120. The motor protector also includes a number of oil expansion bags 175. To take advantage of the high-load bearing system, shaft 133 of seal section 140 and shaft 135 of pump 120 are typically connected by a special coupling 105.
Each shaft 133, 135 has a pin hole 101, 102 at its meeting end with the other shaft. Coupling 105 has pinholes at both ends at the matching point of pinhole 101, 102 of shaft. Two pins 106, 107 are inserted through each matching pinhole 101, 102 during the field installation of pump 120 and seal section 150. Because this coupling 105 and shaft 135 is hidden inside of the pump 120, the pump 120 must be equipped with special access holes 103, 104 to make the installation of the pins 106, 107 possible. In the conventional inverted system 100, this is necessary in order for the thrust load to be transferred from the pump 120, the shaft 135, and the pinned coupling 105 to the shaft 133 and the seal section 150 at the top of the pump 120.

SUMMARY

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to set the scope of the claimed subject matter.
In an aspect, an electrical submersible pump for use in an electrical submersible pumping (ESP) system includes a pump shaft, one or more pump stages each having an impeller or a diffuser, a pump intake configured to suction production fluid into the electrical submersible pump, a pump discharge configured to expel production fluid from the electrical submersible pump, a thrust chamber having a thrust offsetting mechanism configured to counter a thrust force generated by the one or more pump stages, one or more seals configured to separate the thrust chamber from the one or more pump stages, and a single unitary housing which encloses the one or more pump stages, the thrust chamber, the one or more seals, and at least a portion of the pump shaft so that the thrust mechanism, the one or more seals, and the one or more pump stages are housed together.
The pump shaft may be a single, unitary shaft extending along a longitudinal axis of the electrical submersible pump and through the one or more pump stages, the one or more seals, and the thrust chamber.
The pump shaft may be configured to attach to a motor shaft of an adjacent motor.
The electrical submersible pump may be configured to connect to an adjacent motor and a motor shaft positioned directly above the electrical submersible pump so that a top of the electrical submersible pump attaches to a bottom of the motor.
The one or more seals may include a primary seal and a secondary seal.
The electrical submersible pump may further include a bearing space formed between the primary seal and the secondary seal including one or more breathing compartments to adapt to a volume change of lubrication oil resulting from changes in temperature.
The bearing space may be positioned above the one or more pump stages and below the thrust chamber.
The one or more breathing compartments may include at least one of elastomer bags metal bellows.
The thrust offsetting mechanism may include at least one of a bearing runner, an upper bearing, and a lower bearing.
The pump discharge may include pump discharge holes formed at an upper portion of the electrical submersible pump above the one or more pump stages, and the pump intake may be formed at a lower portion of the electrical submersible pump below the one or more pump stages.
The pump discharge may include pump discharge holes formed at a lower portion of the electrical submersible pump below the one or more pump stages, and the pump intake may be formed at an upper portion of the electrical submersible pump above the one or more pump stages.
In another aspect, an electrical submersible pump for use in an electrical submersible pumping (ESP) system includes one or more pump stages, a thrust chamber having a thrust offsetting mechanism configured to counter a thrust force generated by the one or more pump stages, and a single unitary housing which encloses the one or more pump stages and the thrust chamber so that the thrust mechanism and the one or more pump stages are housed together.
The electrical submersible pump may further include a primary seal, a secondary seal, and a bearing space formed above the primary seal and the secondary seal including one or more breathing compartments to adapt to a volume change of lubrication oil resulting from changes in temperature.
The thrust offsetting mechanism may include at least one of a bearing runner, an upper bearing, and a lower bearing.
The electrical submersible pump may be configured to connect to an adjacent motor and a motor shaft positioned directly above the electrical submersible pump so that a top of the electrical submersible pump attaches to a bottom of the motor.
In yet another aspect, an inverted electrical submersible pumping (ESP) system includes a pump including a pump shaft, one or more pump stages, a thrust chamber including a thrust offsetting mechanism configured to counter a thrust force generated by the one or more pump stages, and a single unitary housing which encloses the one or more pump stages and the thrust chamber so that the thrust mechanism and the one or more pump stages are housed together, and a motor including a motor shaft.
The inverted ESP system may further include a motor head and a motor protector positioned above the motor.
The pump may be attached directly to the motor with no other units positioned therebetween, and the pump shaft may be attached directly to the motor shaft.
The pump may further include a primary seal, a secondary seal, and a bearing space formed above the primary seal and the secondary seal comprising one or more breathing compartments to adapt to a volume change of lubrication oil resulting from changes in temperature.
The thrust offsetting mechanism of the pump may include at least one of a bearing runner, an upper bearing, and a lower bearing.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description, will be better understood when read in conjunction with the appended drawings. For the purpose of illustration, certain examples of the present description are shown in the drawings. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of system, apparatuses, and methods consistent with the present description and, together with the description, serve to explain advantages and principles consistent with the invention.

Further features, details and advantages of the invention are explained in the appended claims, in the drawings and in the description of a preferred embodiment of the head section according to the invention given below.

FIG. 1 is a diagram illustrating a prior art ESP system including an intake unit and a seal section installed below a pump and above a motor.

FIG. 2 is a diagram illustrating a prior art inverted ESP system with the position of the pump and the seal section being switched as compared to the typical configuration.

FIG. 3 is a diagram illustrating an inverted ESP system in accordance with an example of the invention.

FIG. 4 is a diagram illustrating the inverted ESP system of FIG. 3 at detail A.

FIG. 5 is a diagram illustrating the inverted ESP system of FIG. 3 at detail B.

Throughout the drawings and the detailed description, unless otherwise described, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. The invention is capable of other embodiments and of being practiced and carried out in various ways. Those skilled in the art will appreciate that not all features of a commercial embodiment are shown for the sake of clarity and understanding. Persons of skill in the art will also appreciate that the development of an actual commercial embodiments incorporating aspects of the present inventions will require numerous implementation specific decisions to achieve the inventors' ultimate goal for the commercial embodiment. While these efforts can be time-consuming, these efforts nevertheless would be a routine undertaking for those of skill in the art having the benefit of this disclosure.
In addition, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. For example, the use of a singular term, such as, “a” is not intended as limiting of the number of items. Also the use of relational terms, such as but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” are used in the description for clarity and are not intended to limit the scope of the invention or the appended claims. Further, it should be understood that any one of the features can be used separately or in combination with other features. Other systems, methods, features, and advantages of the invention will be or become apparent to one with skill in the art upon examination of the detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that the invention disclosed herein is not limited to the particular embodiments disclosed, and is intended to cover modifications within the spirit and scope of the present invention.
FIG. 1 is a diagram illustrating a prior art ESP system including an intake unit and a seal section installed below a pump and above a motor, and FIG. 2 is a diagram illustrating a prior art inverted ESP system with the position of the pump and the seal section being switched as compared to the typical configuration. FIGS. 1 and 2 were previously discussed above in reference to conventional devices which are typically used.
FIG. 3 is a diagram illustrating an inverted ESP system 1000 in accordance with an example of the invention.
Referring to FIG. 3, the inverted ESP system 1000 may include a power connecting head 1010, a motor protector 1020, a motor 1030, and a pump 1040 with an integrated thrust chamber 1045. Because the ESP system 1000 is an inverted system, the pump 1040 having the integrated thrust chamber 1045 is typically positioned at the bottom-most portion of the system. The pump inlet is at the bottom of the pump 1040 providing a bottom-intake design where the production fluid is drawn in the intake ports located at the very bottom of the ESP system 1000 and discharged out of pump discharge ports (described in more detail below) located at the top of the pump 1040. Because the discharged production fluid cannot flow through the motor, it has to exit into the casing or liner annulus. Once past these units, the discharged production fluid may continue flowing up the annulus or may flow back through the production tubing string.
Still referring to the example of FIG. 3, the pump 1040 is a multi-stage centrifugal pump with a number of impellers and diffusers. As a result, a downward thrust force is generated and needs to be offset by a thrust offsetting mechanism. In this example, a thrust chamber 1045 having a thrust offsetting mechanism may include a thrust bearing or a number of other thrust mechanisms known and used in the art. The thrust chamber 1045 is integrated into the pump 1040 so that the pump 1040 is an integrated self-sustained system including a thrust offsetting mechanism. That is, the pump 1040, according to the example of FIG. 3, may be attached directly to the motor 1030 without any additional unit positioned therebetween. In addition, there is no need for a sealing unit or a lower motor adaptor in this configuration thus simplifying the system significantly.
The described system and integrated pump enables the inverted ESP to handle the downthrust force within the pump itself. Unlike the conventional system, the pump shaft does not need to be connected to the seal shaft with a pinned coupling, which is cumbersome and difficult to install in a field. Referring back to FIG. 2, the need for separate shafts 133, 135, pin holes 101, 102, a coupling 105, and pins 106, 107 may be entirely avoided. The elimination of such pin connection will not only reduce the installation time, but also make the system more reliable. Because the thrust bearing is operating with a single shaft in a clean oil environment, this will also increase the lifespan of the system.
FIG. 4 is a diagram illustrating the inverted ESP system 1000 of FIG. 3 at detail A. Referring to FIGS. 3 and 4, the inverted ESP system 1000 includes a power connection 1100 for connecting to the power connecting head 1010, a power cable 1110, an oil breathing port 1120 and oil expansion bags 1130 as part of the motor protector 1020, and a power connection 1140 to the motor 1030. Illustrated in FIG. 4 are the components and units of the inverted ESP system 1000 above the motor 1030. The components above the motor 1030 may be similar to the units and components above the motor of the conventional inverted system illustrated in FIG. 2.
FIG. 5 is a diagram illustrating the inverted ESP system of FIG. 3 at detail B.
Referring to FIG. 5, the pump 1040 with integrated thrust chamber will be explained in more detail. The pump 1040 includes two main integrated sections, a pumping section and a bearing section. The pumping section is located at the lower end of the pump unit 1040 while the bearing section is located at the upper end. However, it should be appreciated that in other examples, the position of the pumping section and the bearing section may be reversed.
The pump 1040 includes a pump shaft 1210 which runs along at least the entire length of the pump 1040 and through both the bearing section and the pumping section of the pump 1040. The pump shaft 1210 is connected to a motor shaft 1230 as illustrated in FIG. 5, and the pump 1040 is directly connected to the motor above it. The bearing section of the pump 1040 may include two bearings, an upper bearing 1250 and a lower bearing 1240. A bearing runner 1220 may be mounted to the shaft 1210 and may rotate between the upper bearing 1250 and the lower bearing 1240.
Pumping section includes a pump intake, one or more pump discharge holes 1260, one or more pump stages 1270, and a compression nut 1280. Each stage may include one impeller and one diffuser. The inverted ESP system can have a number of different pump configurations based on the well condition; for example, a bottom discharge system or a bottom intake system. In a bottom discharge system, intake is at the upper end of the pumping section, and discharge is at the lower end of the pumping section. The production flow comes from the intake body at the upper end and is expelled through the discharge portion at the lower end. In the bottom intake system, intake is at the lower end of the pumping section and discharge is at the upper end. The production flow comes from the intake portion at the lower end and is expelled through the discharge portion at upper end. As illustrated, the shown configuration is a bottom intake system where production flow is expelled through the pump discharge holes 1260.
In this example, the thrust load from the pump stages 1270 will transfer through the shaft 1210 and runner 1220 to the non-rotating bearing surfaces 1240, 1250. The direction of the thrust load can be upward, which is the direction of the thrust load in a bottom discharge system, or downward, which is the direction of the thrust load in a bottom intake system. In between intake and discharge, a number of pumping stages 1270 will be installed along the shaft 1210. Journal bearings may be mounted both at the intake and discharge ends of the pump 1040 to help the pump shaft 1210 rotate stably.
The thrust bearing region may be enclosed by at least one dynamic seal at a lower end. In an example, the pump 1040 may include a primary dynamic seal 1290 and a secondary dynamic seal 1295. The primary dynamic seal 1290 may be formed above the pumping region, i.e. directly above the pump discharge holes 1260. The secondary dynamic seal 1295 may be formed below the thrust bearing region. These seals 1290, 1295 will separate the clean lubrication oil from the production fluid. In this example, the production fluid is expelled through the discharge holes 1260, thus the seals 1290, 1295 will assist in keeping all regions of the pump 1040 above the discharge holes 1260 free from production fluid. Above the primary dynamic seal 1290, one or more breathing compartments adapt to any volume change of lubrication oil resulting from changes in temperature. For example, the breathing compartment may include elastomer bags or, as in this example, metal bellows 1298 for adapting to changes in the volume of the lubrication oil.
One of skill in the art will recognize that the embodiments described above are not limited to any particular size and the size of the pump and other pump system components will depend upon the particular application and intended components. It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that the invention disclosed herein is not limited to the particular embodiments disclosed, and is intended to cover modifications within the spirit and scope of the present invention.

Claims

What is claimed is:

1. An electrical submersible pump for use in an electrical submersible pumping (ESP) system, the electrical submersible pump comprising:

a pump shaft;

one or more pump stages each comprising an impeller or a diffuser;

a pump intake configured to suction production fluid into the electrical submersible pump;

a pump discharge configured to expel production fluid from the electrical submersible pump;

a thrust chamber comprising a thrust bearing configured to counter a thrust force generated by the one or more pump stages;

one or more seals configured to separate the thrust chamber from the one or more pump stages; and

a unitary housing which encloses the one or more pump stages, the thrust chamber, the one or more seals, and at least a portion of the pump shaft so that the thrust bearing, the one or more seals, and the one or more pump stages are housed together.

2. The electrical submersible pump of claim 1, wherein the pump shaft is a unitary shaft extending along a longitudinal axis of the electrical submersible pump and through the one or more pump stages, the one or more seals, and the thrust chamber.

3. The electrical submersible pump of claim 2, wherein the pump shaft is configured to attach to a motor shaft of an adjacent motor.

4. The electrical submersible pump of claim 1, wherein the electrical submersible pump is configured to connect to an adjacent motor and a motor shaft positioned directly above the electrical submersible pump so that a top of the electrical submersible pump attaches to a bottom of the adjacent motor.

5. The electrical submersible pump of claim 1, wherein the one or more seals comprise a primary seal and a secondary seal.

6. The electrical submersible pump of claim 5, further comprising one or more breathing compartments, formed between the primary seal and the secondary seal, to adapt to a volume change of lubrication oil resulting from changes in temperature.

7. The electrical submersible pump of claim 6, wherein the one or more breathing compartments are positioned above the one or more pump stages and below the thrust chamber.

8. The electrical submersible pump of claim 6, wherein the one or more breathing compartments comprises at least one of elastomer bags or metal bellows.

9. The electrical submersible pump of claim 1, wherein the thrust bearing comprises a bearing runner, an upper bearing, or a lower bearing.

10. The electrical submersible pump of claim 1, wherein the pump discharge comprises pump discharge holes formed at an upper portion of the electrical submersible pump above the one or more pump stages, and the pump intake is formed at a lower portion of the electrical submersible pump below the one or more pump stages.

11. The electrical submersible pump of claim 1, wherein the pump discharge comprises pump discharge holes formed at a lower portion of the electrical submersible pump below the one or more pump stages, and the pump intake is formed at an upper portion of the electrical submersible pump above the one or more pump stages.

12. An electrical submersible pump for use in an electrical submersible pumping (ESP) system, the electrical submersible pump comprising:

one or more pump stages;

a thrust chamber comprising a thrust bearing configured to counter a thrust force generated by the one or more pump stages; and

a unitary housing which encloses the one or more pump stages and the thrust chamber so that the thrust bearing and the one or more pump stages are housed together.

13. The electrical submersible pump of claim 12, further comprising:

a primary seal;

a secondary seal; and

one or more breathing compartments, formed between the primary seal and the secondary seal, to adapt to a volume change of lubrication oil resulting from changes in temperature.

14. The electrical submersible pump of claim 12, wherein the thrust bearing comprises at least one of a bearing runner, an upper bearing, and a lower bearing.

15. The electrical submersible pump of claim 12, wherein the electrical submersible pump is configured to connect to an adjacent motor and a motor shaft positioned directly above the electrical submersible pump so that a top of the electrical submersible pump attaches to a bottom of the adjacent motor.

16. An inverted electrical submersible pumping (ESP) system, comprising:

a pump comprising:

a pump shaft;

one or more pump stages;

a unitary housing which encloses the one or more pump stages and the thrust chamber so that the thrust bearing and the one or more pump stages are housed together; and

a motor comprising a motor shaft.

17. The inverted ESP system of claim 16, further comprising a power connection head and a motor protector positioned above the motor.

18. The inverted ESP system of claim 16, wherein the pump is attached directly to the motor with no other units positioned therebetween, and the pump shaft is attached directly to the motor shaft.

19. The inverted ESP system of claim 16, wherein the pump further comprises:

a primary seal;

a secondary seal; and

20. The inverted ESP system of claim 16, wherein the thrust offsetting mechanism of the pump comprises a bearing runner, an upper bearing, or a lower bearing.