SUBMERSIBLE PUMPING SYSTEM HAVING STAGE ARCHITECTURE FOR LOWER FLOW RATE PUMPS

Abstract

A technique facilitates pumping of fluid at a desired flow rate. A submersible pump may be used in, for example, an electric submersible pumping system to pump well fluids or other types of fluids. The submersible pump comprises at least one pump stage disposed within an outer pump housing. Each pump stage has an impeller and a diffuser, the impeller being rotatable relative to the diffuser to pump fluid through the submersible pump. Additionally, the submersible pump incorporates a space out mechanism between the outer pump housing and the at least one pump stage to reduce the pumping capacity of the submersible pump without reducing the external diameter of the outer pump housing.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Singapore Provisional Patent Application No. 10202260550X filed Dec. 22, 2022, the entire contents of which are hereby incorporated in their entirety.

BACKGROUND

In many hydrocarbon well applications, electric submersible pumping (ESP) systems are used for pumping fluids, e.g. hydrocarbon-based fluids. For example, the ESP system may be conveyed downhole and used to pump oil from a downhole wellbore location to a surface collection location along a production tubing. The ESP system comprises various components, including a submersible pump having sequential stages with each stage including an impeller and a cooperating diffuser. The maximum and minimum flow rate of the submersible pump is a function of its construction type; e.g. radial, mixed, or axial flow type; its geometry, e.g. the maximum diameter of the pump impeller/diffuser; and pump design features, e.g. impeller vane opening gap, vane profile, vane thickness.

Traditionally, the pump stages are constructed to utilize the maximum available internal diameter within the external pump housing. This approach facilitates optimization of efficiency by reducing certain fluid losses. However, in some applications, there may be a desire or requirement to reduce the flow rates below a specific, maximum flow rate. This can be accomplished by using a smaller diameter pump, however use of the smaller diameter pump creates a smaller external diameter relative to other equipment in the ESP system. The difference in equipment diameters can create a variety of detrimental operational issues when running the ESP system downhole or when pulling the ESP system out of hole.

SUMMARY

In general, a system and methodology facilitate pumping of fluid at a desired flow rate. A submersible pump may be used in, for example, an electric submersible pumping system to pump well fluids or other types of fluids. The submersible pump comprises at least one pump stage disposed within an outer pump housing. Each pump stage has an impeller and a diffuser, the impeller being rotatable relative to the diffuser to pump fluid through the submersible pump. Additionally, the submersible pump incorporates a space out mechanism between the outer pump housing and the at least one pump stage to reduce the pumping capacity of the submersible pump without reducing the external diameter of the outer pump housing.

However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.

Embodiments directed to a system for pumping are disclosed herein. The system may comprise an electric submersible pumping system having a submersible pump comprising a plurality of pump stages disposed within an outer pump housing, each pump stage having an impeller and a diffuser, the impeller being rotatable relative to the diffuser to pump fluid through the submersible pump, the submersible pump incorporating a space out mechanism between the outer pump housing and the plurality of pump stages to reduce the pumping capacity of the submersible pump without reducing the outer diameter of the outer pump housing.

The space out mechanism may comprise a plurality of ring spacers positioned within the outer pump housing, the plurality of ring spacers having diffuser mounting features positioned to hold corresponding diffusers at a spaced distance from the outer pump housing. The ring spacers may have internal diameters sized to cooperate with corresponding impellers so as to facilitate pumping as the corresponding impellers are rotated within the ring spacers. The space out mechanism may comprise a series of hollow spacers positioned within the outer pump housing, the hollow spacers having diffuser mounting features positioned to hold corresponding diffusers at a spaced distance from the outer pump housing. The hollow spacers may have internal diameters sized to cooperate with the corresponding impellers so as to facilitate pumping as the corresponding impellers are rotated within the hollow spacers.

The space out mechanism may comprise incorporating thicker wall sections along an interior of the outer pump housing, the thicker wall sections having diffuser mounting features positioned to hold corresponding diffusers at a desired position within the outer pump housing. The thicker wall sections may extend continuously along the interior of the outer pump housing. The space out mechanism may comprise a plurality of diffuser inserts positioned within the outer pump housing, each diffuser insert further comprising an impeller section providing a reduced diameter for operatively receiving a corresponding impeller at a desired distance from the outer pump housing. The electric submersible pumping system may further comprise a submersible motor and a motor protector which each share a common external diameter with the submersible pump, the submersible motor being coupled with the submersible pump in a manner enabling rotation of the impellers during pumping. The space out mechanism may be constructed as a unitary solid spacer wall extending along the plurality of pump stages.

A method for pumping, the method comprising: providing a submersible pump with an outer pump housing for containing a plurality of pump stages; incorporating a space out mechanism within the outer pump housing to reduce the pumping capacity of the submersible pump by enabling use of a reduced diameter impeller and a corresponding reduced diameter diffuser in each pump stage without reducing the outer diameter of the outer pump housing; assembling each pump stage with the reduced diameter impeller and the corresponding reduced diameter diffuser, the reduced diameter impeller being rotatable relative to the corresponding reduced diameter diffuser so as to pump fluid through the submersible pump. Incorporating the space out mechanism may comprise incorporating a plurality of ring spacers positioned within the outer pump housing, the plurality of ring spacers having diffuser mounting features positioned to hold corresponding reduced diameter diffusers at a spaced distance from the outer pump housing.

Incorporating the space out mechanism may comprise incorporating a series of hollow spacers positioned within the outer pump housing, the hollow spacers having diffuser mounting features positioned to hold corresponding reduced diameter diffusers at a spaced distance from the outer pump housing.

Incorporating the space out mechanism may comprise incorporating thicker wall sections along the outer pump housing, the thicker wall sections having diffuser mounting features positioned to hold corresponding reduced diameter diffusers at a desired position within the outer pump housing. Incorporating further comprises positioning the thicker wall sections so as to extend continuously along an interior of the outer pump housing. Incorporating the space out mechanism may comprise incorporating a plurality of diffuser inserts within the outer pump housing, each diffuser insert including an impeller section having a reduced diameter for operatively receiving one of the reduced diameter impellers at a desired distance from the outer pump housing.

The plurality of ring spacers may have internal diameters sized to cooperate with corresponding reduced diameter impellers so as to facilitate pumping as the corresponding reduced diameter impellers are rotated within the ring spacers. The hollow spacers may have internal diameters sized to cooperate with corresponding reduced diameter impellers so as to facilitate pumping as the corresponding reduced diameter impellers are rotated within the hollow spacers. The space out mechanism may comprise a plurality of diffuser inserts positioned within the outer pump housing, each diffuser insert further comprising an impeller section providing a reduced diameter for operatively receiving a corresponding reduced diameter impeller at a desired distance from the outer pump housing. The submersible pump may further comprise a submersible motor and a motor protector, wherein each share a common external diameter with the submersible pump, the submersible motor being coupled with the submersible pump in a manner enabling rotation of the reduced diameter impellers of the plurality of stages during pumping. The space out mechanism may be constructed as a unitary solid spacer wall extending along the plurality of pump stages.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:

FIG. 1 is a schematic illustration of a well system comprising an example of a submersible pump, the submersible pump being incorporated into an electric submersible pumping system positioned in a borehole, e.g. a wellbore, according to an embodiment of the disclosure;

FIG. 2 is a cross-sectional view of an example of a submersible pump, according to an embodiment of the disclosure;

FIG. 3 is a cross-sectional view of an example of pump stages within the submersible pump in which a space out mechanism has been employed to enable use of smaller diameter impellers and diffusers within a larger outer housing, according to an embodiment of the disclosure;

FIG. 4 is a cross-sectional view of pump stages within the submersible pump in which another example of a space out mechanism has been employed to enable use of smaller diameter impellers and diffusers within a larger diameter outer housing, according to an embodiment of the disclosure; and

FIG. 5 is a cross-sectional view of pump stages within the submersible pump in which another example of a space out mechanism has been employed to enable use of smaller diameter impellers and diffusers within a larger diameter outer housing, according to an embodiment of the disclosure.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

The present disclosure generally relates to a system and methodology which facilitate lower flow rate operation of a pump, such as a submersible pump in an electric submersible pumping system. The submersible pump is constructed with a stage architecture which effectively establishes a lower flow rate pump. According to an embodiment, the submersible pump may be in the form of a centrifugal pump having at least one stage with an impeller and a diffuser. In many applications, the pump comprises a plurality of stages having sequential pairs of cooperating impellers and diffusers disposed within a surrounding pump housing. The impellers are rotated by a shaft and move relative to the diffusers to pump fluid along a flow path within the pump housing until the fluid is discharged through a discharge head.

According to an embodiment, the submersible pump may be used in, for example, an electric submersible pumping system to pump well fluids or other types of fluids. The submersible pump is operable to move fluid via at least one pump stage disposed within the surrounding outer pump housing. Each pump stage has a reduced diameter impeller and a reduced diameter diffuser, the impeller being rotatable relative to the diffuser to pump fluid along a flow path through the submersible pump. Additionally, the submersible pump incorporates a space out mechanism between the outer pump housing and the at least one pump stage to accommodate the reduced diameter impeller/diffuser and to thus reduce the pumping capacity of the submersible pump without reducing the external diameter of the outer pump housing.

Referring generally to FIG. 1, an example of a pump 20, e.g. a submersible, centrifugal pump, is illustrated as deployed in a well-related application.

However, the illustrated embodiment is simply provided as an example of numerous potential embodiments that may utilize the reduced flow output architecture as described herein. Referring again to FIG. 1, pump 20 may be deployed in a submersible pumping system 22, e.g. an electric submersible pumping system.

The submersible pumping system 22 may comprise a variety of components depending on the particular well application and/or environment in which it is used. In addition to the submersible pump 20, other components of submersible pumping system 22 may comprise at least one submersible motor 24 and at least one motor protector 26. The motor protector 26 enables pressure balancing of the internal motor fluid of submersible motor 24 with respect to the surrounding environment. The submersible pump 20, submersible motor 24, and motor protector 26 are coupled together into electric submersible pumping (ESP) system 22 in a manner such that submersible motor 24 may be selectively operated to power the submersible pump 20. In some embodiments, a plurality of submersible pumps 20, e.g., tandem submersible pumps, may be employed.

The submersible pumping system 22 may be deployed in a wellbore 28 drilled into a geologic formation 30 containing, for example, desirable production fluids such as hydrocarbon-based fluids. In some applications, the electric submersible pumping system 22 may be positioned vertically in a vertical section of wellbore 28 but in other applications electric submersible pumping system 22 may be positioned in a deviated, e.g. horizontal, sectional wellbore 28. It should be noted wellbore 28 may comprise various types of boreholes used for production, injection, or other pumping operations. In some applications, the wellbore 28 may be lined with a wellbore casing 32 which may be perforated with a plurality of perforations 34 extending through the casing 32 and into the surrounding formation 30. The perforations 34 enable flow of fluids between the surrounding formation 30 and the wellbore 28.

The submersible pumping system 22 may be deployed downhole into wellbore 28 via a conveyance 36. The conveyance 36 may have a variety of configurations and may comprise a tubing 38, e.g. coiled tubing or production tubing. However, other suitable conveyances, such as wireline or slick line, also may be used to deploy submersible pumping system 22. The conveyance 36 may be coupled with submersible pumping system 22 by an appropriate connector 40 which may comprise or may be coupled with a discharge head 42 which receives and discharges fluid pumped by submersible pump 20.

Electric power may be provided to submersible motor 24 via a power cable 44 which extends along conveyance 36 and submersible pumping system 22 for connection with submersible motor 24. The submersible motor 24, in turn, powers submersible pump 20 which then draws in fluid from wellbore 28 through a pump intake 46. By way of example, the submersible motor 24 may power submersible pump 20 via a pump shaft used to rotate at least one impeller.

Within submersible pump 20, for example, a plurality of impellers may be rotated to pump fluid from intake 46, through submersible pump 20, and out through a discharge head 42. The discharged fluid may be directed along an interior of tubing 38 (or along another suitable flow path) to a desired location, such as a collection location at the surface. However, various other components and system configurations may be utilized in a variety of pumping operations and environments.

Referring generally to FIG. 2, an embodiment of pump 20 is illustrated in the form of a submersible, centrifugal pump. In this embodiment, the submersible pump 20 comprises a plurality of pumps stages 48 distributed along a substantial portion of its length. In FIG. 2, a relatively small number of the actual pump stages 48 is illustrated to facilitate explanation; however pump stages 48 would tend to be distributed along a substantial length of the submersible pump 20. As illustrated, the submersible pump 20 also comprises an outer pump housing 50 which may be tubular in shape and house the pump stages 48. A shaft 52 may be rotatably mounted within the outer pump housing 50 generally along a central pump axis of the submersible pump 20.

The pumps stages 48 may comprise a plurality of pairs of cooperating diffusers 54 and impellers 56. The illustrated diffusers 54/impellers 56 are in the form of reduced diameter diffusers 54 and reduced diameter impellers 56 relative to a diameter of the outer pump housing 50. By reducing the diameters of the diffusers 54 and impellers 56 without reducing the external diameter of outer pump housing 50, a reduced flow rate of submersible pump 20 is achieved. In other words, the impellers 56 may be rotated with respect to diffusers 54 at a desirable, e.g. optimal, rotational speed while effectively reducing the output of submersible pump 20 relative to what the output of the pump would be with full sized impellers and diffusers.

As explained in greater detail below, the ability to employ reduced diameter diffusers 54 and reduced diameter impellers 56 results from the use of a space out mechanism 58. The space out mechanism 58 is positioned between the outer pump housing 50 and the plurality of pump stages 48 to reduce the pumping capacity of the submersible pump 20 without reducing the outer diameter of the outer pump housing 50. With this approach, the pump stages 48 are not designed to utilize the maximum available internal diameter within the pump housing as with conventional pumps. Instead, the pump stages 48 may be constructed with a reduced diameter resulting in a desired, reduced fluid flow without decreasing the external diameter of the submersible pump 20.

It should further be noted the reduced flow rate may be achieved while leaving the external diameter of outer pump housing 50 consistent with the outer diameter of other system components, e.g submersible motor 24 and motor protector 26. Maintaining a general consistency of external diameters along pumping system equipment avoids creation of various detrimental operational issues when running the ESP system 22 downhole or when pulling the ESP system 22 out of hole. Furthermore, the ability to reduce the flow rate of submersible pump 20 without changing the optimized or otherwise desirable rotational speed of impellers 56 is beneficial in a variety of pumping operations. Examples of such pumping operations include production operations from wells which have deteriorated such that insufficient well fluid is able to flow into the wellbore 28 to meet the pumping capacity of a conventionally optimized pump with full-sized impellers and diffusers.

In the embodiment illustrated, the reduced diameter impellers 56 are mounted on shaft 52 for rotation with the shaft 52. In each stage 48, the reduced diameter impeller 56 is rotatable with respect to the corresponding diffuser 54 while remaining rotationally affixed with shaft 52. For example, the shaft 52 may be keyed or otherwise coupled with the plurality of impellers 56 so as to rotate the plurality of impellers 56 with respect to the plurality of corresponding diffusers 54. The shaft 52 is rotated by submersible motor 24.

During operation, the rotating, reduced diameter impellers 56 effectively create a low-pressure or suction which draws fluid in through pump intake 46 and imparts motion to the fluid. The rotating impellers 56 cause the fluid to flow along a primary flow path through submersible pump 20 from one stage 48 to the next until the fluid is discharged through discharge head 42. For example, the fluid pumped via rotating impellers 56 may be directed along flow passages through discharge head 42 and into tubing 38 or to another suitable flow path.

In FIG. 1, one example of space out mechanism 58 is illustrated. However, the space out mechanism 58 may have a variety of sizes and configurations depending on the desired reduction in impeller/diffuser diameter and/or desired reduction in overall flow rate through submersible pump 20. The space out mechanism 58 also may be adjusted according to the types of impellers and diffusers, e.g. radial impellers, mixed flow impellers, axial flow impellers, or other types of impellers.

As illustrated, the space out mechanism 58 may be in the form of a plurality of ring spacers 60 positioned within the outer pump housing 50. The ring spacers 60 have sufficient thickness in the radial direction to achieve a desired spacing between the outer pump housing 50 and the effective outer diameter of reduced diameter diffusers 54 and reduced diameter impellers 56. The ring spacers 60 also may comprise diffuser mounting features 62 positioned to hold corresponding diffusers 54 at a spaced distance 64 from the outer pump housing 50.

By way of example, the ring spacers 60 may span from one diffuser 54 to the next adjacent diffuser 54 so as to provide a reduced diameter inner surface 66 along which the corresponding reduced diameter impeller 56 is able to rotate. The relative motion between the impeller 56 and inner surface 66 causes the desired pumping as the impellers 56 are rotated within the ring spacers 60.

In some embodiments, the ring spacers 60 are longitudinally or axially spaced from each other to create gaps 68 along the interior of outer pump housing 50. In other embodiments, however, the ring spacers 60 may be constructed with greater longitudinal length so as to abut against one another. The abutting ring spacers 60 effectively create a solid spacer wall along the interior of outer pump housing 50.

Depending on the construction of diffusers 54 and impellers 56, the space out mechanism 58 also may be constructed as a single, unitary solid spacer wall extending along the multiple stages 48. In such an embodiment, the cooperating diffusers 54 and impellers 56 may be constructed so as to stack together within this single spacer wall. In some embodiments, the space out mechanism 58 may be attached to or may be formed as part of the outer pump housing 50. For example, the space out mechanism 58 may be in the form of a thicker solid or interrupted wall section disposed along the interior of the outer pump housing 50. The thicker wall section(s) may be constructed with diffuser retention features 62 so as to secure both diffusers 54 and impellers 56 at desired interior locations.

Furthermore, the ring spacers 60 may be in the form of hollow spacers having hollowed out recesses 70, as illustrated in FIG. 3. The recesses 70 may have a variety of sizes, numbers, and configurations selected to, for example, lighten the ring spacers 60 and to facilitate assembly of the submersible pump 20. The hollow ring spacers 60 also may comprise diffuser mounting features 62 to facilitate mounting of the diffusers 54 within outer pump housing 50 at the desired spaced distance 64. In other embodiments, however, the ring spacers 60 may be in the form of solid rings, as illustrated in FIG. 4.

Additionally, the space out mechanism 58 may comprise a plurality of diffuser inserts 72, as illustrated in FIG. 5. The diffuser inserts 72 may be positioned within the outer pump housing 50 so as to secure the corresponding reduced diameter diffusers 54 at the desired internal location. By way of example, each diffuser insert 72 may further comprise an impeller section 74 providing a reduced diameter surface 76 for operatively receiving a corresponding reduced diameter impeller 56 at a desired distance 64 from the outer pump housing 50.

Depending on the parameters of a given application and/or environment, embodiments described herein may utilize various structures to achieve the desired lower flow rate pump 20 while using a larger sized housing, e.g. a larger standard sized housing. Additionally, the ratio of the effective diameter of the flow passage within the pump to the external diameter of the pump may have a substantial range, e.g. 0.5 to 0.9, to achieve the desired reduced pump flow rate while operating the submersible motor 24 and the impellers 56 at a desired or optimized rotational speed. Additionally, the configuration of the diffusers 54 and impellers 56 may be selected according to the parameters of a given pumping operation. The space out mechanism 58 also may be constructed in various configurations, including removable, stackable spacers; thicker sections along the outer pump housing 50; expanded diffuser walls; and/or other combinations of features to achieve the desired spaced distance 64 and reduced flow passage within the larger outer pump housing 50.

Additionally, the overall size and structure of pump 20 and/or submersible pumping system 22 may be adjusted to accommodate many types of pumping applications. For example, the submersible pumping system 22 may be in the form of an electric submersible pumping system combined with other components for use in a wellbore or other type of borehole. Similarly, the number and arrangement of pump stages 48 of submersible pump 20 may vary. The style of pump stages 48 may be in the form of axial flow stages, radial flow stages, mixed flow stages, or other suitable pump stage styles to achieve the desired flow in a given pumping environment.

Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.

Claims

1. A system for pumping, comprising:

an electric submersible pumping system having a submersible pump comprising a plurality of pump stages disposed within an outer pump housing, each pump stage having an impeller and a diffuser, the impeller being rotatable relative to the diffuser to pump fluid through the submersible pump, the submersible pump incorporating a space out mechanism between the outer pump housing and the plurality of pump stages to reduce the pumping capacity of the submersible pump without reducing the outer diameter of the outer pump housing.

2. The system as recited in claim 1, wherein the space out mechanism comprises a plurality of ring spacers positioned within the outer pump housing, the plurality of ring spacers having diffuser mounting features positioned to hold corresponding diffusers at a spaced distance from the outer pump housing.

3. The system as recited in claim 2, wherein the ring spacers have internal diameters sized to cooperate with corresponding impellers so as to facilitate pumping as the corresponding impellers are rotated within the ring spacers.

4. The system as recited in claim 1, wherein the space out mechanism comprises a series of hollow spacers positioned within the outer pump housing, the hollow spacers having diffuser mounting features positioned to hold corresponding diffusers at a spaced distance from the outer pump housing.

5. The system as recited in claim 4, wherein the hollow spacers have internal diameters sized to cooperate with the corresponding impellers so as to facilitate pumping as the corresponding impellers are rotated within the hollow spacers.

6. The system as recited in claim 1, wherein the space out mechanism comprises incorporating thicker wall sections along an interior of the outer pump housing, the thicker wall sections having diffuser mounting features positioned to hold corresponding diffusers at a desired position within the outer pump housing.

7. The system as recited in claim 6, wherein the thicker wall sections extend continuously along the interior of the outer pump housing.

8. The system as recited in claim 1, wherein the space out mechanism comprises a plurality of diffuser inserts positioned within the outer pump housing, each diffuser insert further comprising an impeller section providing a reduced diameter for operatively receiving a corresponding impeller at a desired distance from the outer pump housing.

9. The system as recited in claim 1, wherein the electric submersible pumping system further comprises a submersible motor and a motor protector which each share a common external diameter with the submersible pump, the submersible motor being coupled with the submersible pump in a manner enabling rotation of the impellers during pumping.

10. The system as recited in claim 1, wherein the space out mechanism is constructed as a unitary solid spacer wall extending along the plurality of pump stages.

11. A method for pumping, the method comprising:

providing a submersible pump with an outer pump housing for containing a plurality of pump stages;

incorporating a space out mechanism within the outer pump housing to reduce the pumping capacity of the submersible pump by enabling use of a reduced diameter impeller and a corresponding reduced diameter diffuser in each pump stage without reducing the outer diameter of the outer pump housing;

assembling each pump stage with the reduced diameter impeller and the corresponding reduced diameter diffuser, the reduced diameter impeller being rotatable relative to the corresponding reduced diameter diffuser so as to pump fluid through the submersible pump.

12. The method as recited in claim 11, wherein incorporating the space out mechanism comprises incorporating a plurality of ring spacers positioned within the outer pump housing, the plurality of ring spacers having diffuser mounting features positioned to hold corresponding reduced diameter diffusers at a spaced distance from the outer pump housing.

13. The method as recited in claim 11, wherein incorporating the space out mechanism comprises incorporating a series of hollow spacers positioned within the outer pump housing, the hollow spacers having diffuser mounting features positioned to hold corresponding reduced diameter diffusers at a spaced distance from the outer pump housing.

14. The method as recited in claim 11, wherein incorporating the space out mechanism comprises incorporating thicker wall sections along the outer pump housing, the thicker wall sections having diffuser mounting features positioned to hold corresponding reduced diameter diffusers at a desired position within the outer pump housing.

15. The method as recited in claim 14, wherein incorporating further comprises positioning the thicker wall sections so as to extend continuously along an interior of the outer pump housing.

16. The method as recited in claim 11, wherein the space out mechanism comprises a plurality of diffuser inserts positioned within the outer pump housing, each diffuser insert further comprising an impeller section providing a reduced diameter for operatively receiving a corresponding reduced diameter impeller at a desired distance from the outer pump housing.

17. The method as recited in claim 12, wherein the plurality of ring spacers have internal diameters sized to cooperate with corresponding reduced diameter impellers so as to facilitate pumping as the corresponding reduced diameter impellers are rotated within the ring spacers.

18. The method as recited in claim 14, wherein the hollow spacers have internal diameters sized to cooperate with corresponding reduced diameter impellers so as to facilitate pumping as the corresponding reduced diameter impellers are rotated within the hollow spacers.

19. The method as recited in claim 11, wherein the submersible pump further comprises a submersible motor and a motor protector, wherein each share a common external diameter with the submersible pump, the submersible motor being coupled with the submersible pump in a manner enabling rotation of the reduced diameter impellers of the plurality of stages during pumping.

20. The method as recited in claim 11, wherein the space out mechanism is constructed as a unitary solid spacer wall extending along the plurality of pump stages.