ARTIFICIAL LIFT PUMP

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of Singapore Provisional Application No. 10202402077Y filed July 15, 2024, the entirety of which is incorporated by reference herein and should be considered part of this specification.

BACKGROUND

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

In certain wells, artificial means are required to increase the flow of liquids, such as crude oil or water, from the reservoir to the surface. This may be due to insufficient pressure in the reservoir, or a need to increase the liquid flow rate. Usually, a pump is used for this purpose.

Pump construction for artificial lift applications is classified into two types based on the mechanism of handling the thrust generated by their pump stage, namely compression type and floater type. In compression type pumps, the impellers of the pump are stacked one on top of another so that the downthrust generated is transferred to the protector thrust bearing. In floater type pumps, each impeller of the pump rests on its adjacent diffuser, hence transferring the generated thrust directly onto the diffuser stack. The configuration of compression type pumps allows the downthrust to be handled in a clean oil environment, while the downthrust generated in floater type pumps is handled under the well fluid conditions within the pump itself. This intelligent compression pumps comprises features of both compression and floater pumps, taking advantage of the benefits of both designs.

Compared to floater type pumps, compression type pumps have a clear advantage of reliability due to their handling of thrust load in a clean fluid environment. However, compression type pumps do introduce some complexities when an operation requires long pump sections with several hundred stages. Under operational conditions, the downthrust loads generated by each stage induces an elastic deformation. With increased number of stacked up stages, the cumulative deformation of all stages results in a significant magnitude of stack deflections, which may lead to accelerated deterioration of pump components, loss of lift/head, and eventually pump failure.

Therefore, there is a need for a pump with an increased reliability compared to available pump types.

SUMMARY

A pump for pumping fluid may include a plurality of impellers stacked on top of each other via a pump shaft. A diffuser may correspond to each impeller. A body may house the plurality of impellers, each corresponding diffuser, and the pump shaft. A protector thrust bearing may be positioned at a first end of the pump shaft.

A gap may be provided at a second end of the pump shaft, and may be configured to allow at least one of the plurality of impellers to float when one or more stage deflections exceed a shaft lift. Alternatively or additionally, a spring may be positioned at the second end of the pump shaft and may be configured to secure the plurality of impellers.

The plurality of impellers may be stacked hub-to-hub and may be configured to move along the shaft in an upward direction. A downthrust generated by the plurality of impellers may be transferred to the protector thrust bearing through the shaft. The pump may be configured to limit the transfer of thrust load such that, when a deflection exceeds a shaft lift, the thrust load from the affected stages may be transferred to an adjacent diffuser. The pump may be part of an electric submersible pump (ESP) system.

The bottom of the pump shaft or an impeller hub may comprise a two-piece ring held in place with a spacer and a retaining ring.

An electric submersible pump (ESP) may include a plurality of impellers and a plurality of diffusers corresponding to each of the impellers. A pump shaft may connect the impellers, and a protector thrust bearing may be located at a bottom end of the shaft. A clearance or spring may be positioned at a top end of the shaft and may be configured to allow limited impeller movement during stage deflection in order to reduce thrust transfer.

A gap may be provided at a second end of the shaft to allow at least one impeller to float when stage deflection exceeds shaft lift. A spring may also be used at the second end to secure the impellers. The impellers may be configured to float at the top end of the shaft via the gap. Downthrust generated by one or more impellers may be transferred to the protector thrust bearing through the shaft. The ESP may be configured to limit thrust transfer such that, when deflection exceeds shaft lift, the thrust load from those stages may be transferred to an adjacent diffuser. A retaining ring, a spacer, and a two-piece ring may be included to transfer thrust load from one or more impellers to the pump shaft.

One or more of the plurality of impellers may include an unconstrained end. The unconstrained end may not be axially locked to the shaft, allowing limited axial movement during operation.

A method of reducing wear in a pump may include stacking a plurality of impellers on a pump shaft. A diffuser may be provided corresponding to each impeller. The plurality of impellers, each corresponding diffuser, and the pump shaft may be housed in a body. A protector thrust bearing may be provided at one end of the pump shaft. A clearance or spring may be provided at the other end of the pump shaft to allow for impeller float during deflection.

The method may further include allowing one or more of the plurality of impellers to float, via a gap, when one or more stage deflections exceed a shaft lift. The method may also include limiting the transfer of a thrust load such that, when a deflection exceeds a shaft lift, the thrust load from only the affected stage may be transferred to an adjacent diffuser.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIGS. 1A-1C show examples of a compression type pump, according to one or more examples of the disclosure.

FIG. 2 shows an example of a compression type pump generating downthrust, according to one or more examples of the disclosure.

FIG. 3 shows an example of reliability issues arising in a compression type pump, according to one or more examples of the disclosure.

FIG. 4A-4B show a comparison between an embodiment of a pump described in the present disclosure and an existing compression type pump, according to one or more examples of the disclosure.

FIG. 5A-5C show a comparison between a compression pump, a floater pump, and an intelligent compression pump, according to one or more examples of the disclosure.

FIG. 6 shows an example 2-piece ring design, according to one or more examples of the disclosure.

FIG. 7 shows an example of an intelligent compression pump, according to one or more examples of the disclosure.

DETAILED DESCRIPTION

Illustrative examples of the subject matter claimed below will now be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual implementation, numerous implementation- specific decisions may be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

FIG. 1A shows an example of a compression type pump 100, as well as the arrangement of components within the pump during when its pump shaft is fully up and fully down. Under normal operating conditions, compression type pumps have a high degree of reliability due to their handling of thrust load in a clean fluid environment. However, in some operating conditions, such as conditions that require long pump sections with high number of pump stages, certain complication arises. Compression type pump 100 may comprise diffuser and housing stack 102. Compression type pump 100 may also comprise impeller and shaft stack 104. Compression type pump 100 may also comprise a protector thrust bearing 106. A protector thrust bearing may be a mechanical bearing located at the bottom end of the pump shaft, designed to absorb and manage axial downthrust loads transmitted through the shaft from the impellers, in order to protect the motor and ensure long-term reliability.

The body housing (or simply housing) may be the outer casing that encloses the internal components of the pump, including the shaft, the impellers, and the diffusers. A diffuser may be a non- rotating, flow-directing element located radially around and downstream of an impeller in a pump stage. An impeller may be a rotating component that draws fluid in and accelerates it outward (radially) using centrifugal force.. The housing may provide structural support, pressure containment, and alignment for the internal components. The housing may typically be made of corrosion-resistant metal and designed to withstand high pressures and harsh downhole environments.

FIG. 1B shows an example of the compression type pump 100 with the shaft fully up 108. The shaft (or pump shaft) may be a long, cylindrical mechanical element that runs axially through the center of the pump. It may serve as the rotational axis for the impellers and transfer mechanical torque from the motor to the impellers. In compression-type ESPs, the shaft also transfers axial thrust loads (downthrust) from the impellers to the protector thrust bearing. The shaft may include grooves or features to accommodate retaining rings, spacers, or springs.

FIG. 1C shows an example of the compression type pump 100 with the shaft fully down 112. The difference in height between the shaft fully up 108 and the shaft fully down 112 may be known as free play or shaft play 110.

FIG. 2 shows an example of a compression type pump 200 generating downthrust through the movement of its pump shaft. As downthrust loads generated by each pump stage induces an elastic deformation, increased number of stacked up stages may result in significant magnitude of stack deflections. When the deflection of the pump stages during downthrust exceeds the value by which the pump shaft has been lifted to load the protector thrust bearing 206, one or more downthrust washers engage and start rubbing. The shaft thrust per stage (discharge pressure times shaft area) 202 and impeller thrust per stage 204, when combined (e.g., added), may give a thrust per stage 208. A total downthrust generated may be calculated by multiplying the thrust per stage by the number of stages in the pump. In some embodiments, several pumps may be employed in tandem such that the load on the protector thrust bearing 206 is combined (e.g., added, multiplied).

Deflection may comprise the axial or radial movement of a component from its original position due to mechanical forces. Deflection typically takes place at the top of pump. Deflection may occur when the downthrust generated by the impellers exceeds the structural stiffness of the pump stack. The stacked components (impellers, diffusers, shaft) may elastically deform or move, especially in long or high-stage pumps. The axial thrust generated by each impeller stage adds up as you move upward through the pump. This causes the greatest total deflection to occur at the top of the pump, because the bottom stages are supported directly by the protector thrust bearing and the top stages are supported only by the flexing structure beneath them. The impellers may be fixed to the shaft, but the diffusers may be fixed to the housing. As the shaft deflects downward, the impellers may move with it, but the diffusers may stay in place. This causes the top impellers to rub against the top diffusers first because the relative movement is greatest at the top.

A diffuser may be a stationary hydraulic component located adjacent to each impeller. Its primary function may be to convert the high-velocity fluid discharged by the impeller into pressure energy by gradually expanding the flow path. Diffusers may also help guide the fluid to the next stage and may include pads or thrust surfaces to absorb axial loads. In some designs, diffusers also act as mechanical stops for impellers during deflection or thrust events.

A stage in an electrical submersible pump (ESP) may refer to a single impeller-diffuser pair. Each stage may contribute a portion of the total head (pressure) generated by the pump. ESPs are multi-stage pumps, meaning they stack many stages in series to achieve the required lift. The number of stages is determined by the desired flow rate and lift height.

An ESP may be a multistage centrifugal pump system designed to operate submerged in a wellbore. An ESP may consist of a motor (usually at the bottom), a seal/protector section, and pump section (with impellers and diffusers). ESPs are used to lift fluids (oil, water, etc.) from deep underground reservoirs to the surface. They are widely used in oil and gas production, water wells, and dewatering applications.

FIG. 3 shows an example of reliability issues arising in a compression type pump 300. Since the cumulative deflection magnitude is the highest at the top section of a top tandem pump, as seen in FIG. 3, the washers at this section are the first ones to start wearing out. Washers (often called shims or spacers) may be used to control the axial clearance between the impeller and diffuser or surrounding components. This axial clearance may aid in proper hydraulic alignment and minimizing axial thrust loads. Once the washers are worn off, any further deflection of the pump stages will lead to metal-to- metal rubbing of the impellers against the diffusers, again starting from the top section of the pump. This leads to accelerated deterioration of pump components, loss of fluid head/lift, and could eventually lead to failure of the pump system. Stage deflections may lead to the top impeller contacting the top diffuser. Since the impellers are locked to the shaft in compression pumps, the entire pump downthrust is transferred to the top diffuser 302. Some embodiments of the present disclosure are directed to increasing reliability of pumps by addressing the above deflection issues.

Turning to FIGS. 4A-4B, a comparison between a compression type and another pump, according to one or more examples of the disclosure. In one or more embodiments, a pump system may be configured similarly as a compression type pump, which may comprise a pump shaft with a plurality of diffuser and housing stack with a corresponding number of impeller hubs and shaft stack, and one end (e.g., bottom end) of the pump shaft being a protector thrust bearing, with an addition of a clearance at another end (e.g., top end) of the pump shaft between the impellers and the pump shaft. The housing stack may refer to the assembled outer casing structure that encloses and supports the internal components of the pump particularly the diffusers, impellers, and shaft stack. The top end may be at or around an uppermost axial end of the pump shaft, on the opposite side of the shaft compared to the protector thrust bearing, where clearance or spring elements may be located to accommodate axial movement. The bottom end may be at or around a lowermost axial end of the pump shaft, where the protector thrust bearing is positioned to receive and manage downthrust loads. A protector thrust bearing may be a mechanical bearing located at the bottom end of the pump shaft, designed to absorb and manage axial downthrust loads transmitted through the shaft from the impellers, in order to protect the motor and ensure long-term reliability. In one pump construction 400 of FIG. 4A, there may be a top spacer (e.g., a cylindrical ring) 402 on the upper end of the shaft above the top diffuser. In the intelligent compression pump structure 406 of FIG. 4B, a gap or a spring may be used to mitigate deflection. In one or more embodiments, instead of a gap or clearance at the top end of the pump shaft, a low stiffness spring (e.g., approximately 5 newtons/inch to 30 newtons/inch) may be used, as seen in FIG. 4. The spring may be an elastic component (e.g., comprised of metal) configured to absorb axial movement and reduce thrust transfer during stage deflection.

FIG. 5A shows a compression pump 500 with a deflection of the upper impeller on the diffuser. FIG. 5B shows a floater pump 510. In the floater pump 510, the impellers are not mechanically fixed to the shaft. Instead, they are designed to float axially along the shaft within a limited range. Impellers float slightly up or down depending on the hydraulic forces acting on them. Axial thrust (caused by pressure differences during pumping) is absorbed by individual impeller bearings, diffuser pads, or thrust washers rather than being transmitted to the motor. When load changes, the impellers self-adjust their axial position. In a floater pump architecture 510, the impeller hub (the central part of the impeller that fits around the shaft) is not locked to the shaft. There is a small axial gap between the impeller hub and the shaft stop (such as a ring, collar, or shoulder). This gap allows the impeller to slide slightly along the shaft when thrust forces change.

FIG. 5C shows an embodiment of an intelligent compression pump. In this configuration, the impellers are stacked one on top of another, hub-to-hub, so that the generated downthrust is transferred down to the shaft (e.g., using a 2-piece ring), and eventually to the protector thrust bearing. Hub-to- hub stacking may comprise a stacking configuration of impellers in which the central hub portions of adjacent impellers are placed directly against each other along the shaft. The hub is the central part of the impeller that fits around the shaft. In a hub-to-hub stack, the impellers may be aligned and pressed together at their hubs, forming a continuous mechanical path for thrust transfer.

Transfer may comprise the mechanical conveyance of axial thrust loads from one component (e.g., impeller) to another (e.g., diffuser, thrust bearing, spring, retaining ring, spacer 2-piece ring) through structural contact or intermediary elements. The upper shaft may have a gap 504. The gap may be an axial space between the impeller and adjacent diffuser or shaft component, allowing limited impeller movement during deflection. A thrust washer may be located at the top stage. A thrust washer may be a bearing surface inside the pump that absorbs axial loads-especially upthrust from the impellers. The thrust washer may prevent metal-on-metal contact and mechanical damage when the shaft moves upward or downward during startup, shutdown, or varying flow conditions.

A thrust washer may be a stationary axial load-bearing surface/component. The thrust washer may not rotate with the shaft and may not transfer axial load into the shaft. The thrust washer may receive axial thrust from a rotating component (like a floating impeller) and transfer that thrust into a stationary structure, such as the diffuser, the pump housing, or a bearing carrier. In an intelligent compression pump, when an impeller floats and contacts the thrust washer, the axial load may be transferred from the impeller (e.g., via the impeller hub) to the thrust washer. The thrust washer may then transfer that load into the surrounding stationary structure (e.g., the diffuser or housing), not back into the shaft. The shaft may be bypassed in this mode, thus localizing thrust absorption and reducing shaft loading.

The thrust washer may prevent direct metal-to-metal contact between moving and stationary parts, distribute load over a flat surface to reduce wear, and allow limited axial movement (in floating impellers) while still providing a stop. When an impeller deflects and floats, the thrust washer may only be in temporary contact with the impeller (e.g., impeller hub).

Under deflection, impellers 506 may behave like a floater pump. The pump 512 may have one or more gaps between impeller hubs (e.g., stacked impeller hubs). The one or more gaps between impeller hubs may enable axial float of the impellers. The gaps may allow certain impellers-especially those near the top of the stack-to move axially when the shaft deflects or when thrust conditions change. The impellers may not be rigidly locked at both ends. Impellers can float upward relative to the shaft when downthrust is reduced or shaft lift increases. The intelligent compression pump, in compression mode, has the shaft fully engaged, the impellers are stacked hub-to-hub and transmit thrust through the shaft. In floater mode, when shaft deflection occurs, the gaps allow impellers to lift and float, absorbing thrust locally. This floating results in improved reliability and efficiency of the pump. By allowing selective float, the design accommodates shaft deflection without damaging components, reduces wear on thrust washers and bearings, and enhances pump performance under variable load conditions.

Stage deflections may lead to top impellers contacting with top or bottom diffuser(s). The impeller hubs are not locked at the top end (e.g., second end) with the shaft, the impellers are allowed to float (e.g., in some embodiments in contact with the thrust washer and in other embodiments not in contact with the thrust washer) in the event the stage deflections exceed the shaft lift. Floating may be a condition where impellers are not rigidly fixed to the shaft and can move axially within a limited range in response to hydraulic or mechanical forces. The shaft lift may be a gap between the impeller and the adjacent diffuser on top and/or bottom. Shaft lift may refer to the vertical displacement range of the pump shaft, typically defined by the gap between impellers and diffusers, which determines when impellers begin to float. Only a single stage thrust load may be transferred to each diffuser/thrust washer. Therefore, when the top impeller downthrust washer engages, the thrust load from only one stage is transferred to the adjacent diffuser, instead of the entire pump downthrust (as with compression type pumps of FIG. 5A). In intelligent compression pump 512, impellers 508 continue to operate as compression impellers as they are not subject to deflection. Thus, intelligent compression pump 512 may initially operate as a compression pump (e.g., at higher speeds), and individual stages may be deflected into floater stages. The intelligent pump 512 thus avoids some of the challenges of full floater pumps (e.g., operating in sandy conditions, rubbing and eroding parts, including thrust washers).

FIG. 6 shows an example 2-piece ring design 600 with a retaining ring 602, a spacer 604, and a 2-piece ring 606, according to one or more examples of the disclosure.

The 2-piece ring may be a split ring. A split ring may be a type of mechanical fastener or retaining component that is designed to fit into a groove on a shaft or inside a bore to hold components in place axially. It's called a "split" ring because it is not a complete circle-it has a gap or split that allows it to be compressed or expanded slightly during installation or removal. The 2-piece ring design may comprise a retaining ring 602. Retaining ring 602, also referred to as a snap ring or circlip, may be employed within the pump assembly as a mechanical stop to axially secure and position internal components-such as impellers or diffusers-along the pump shaft, thereby preventing undesired axial displacement, maintaining precise alignment of stacked elements, and ensuring mechanical integrity during high-speed rotational operation.

In a typical compression pump, the impeller (e.g., via the impeller hub) is in contact with 2- piece ring. However, in this 2-piece ring design, a widened groove is made to accommodate the retaining ring 602 and a spacer 604, which may provide security when the impeller shifts. A groove may be located on the shaft (e.g., at the top or bottom of the shaft or impeller) to install the retaining ring. The impeller can move up or down because of the gap (e.g., 704) between the top edge of the 2- piece ring and the bottom end of the retaining ring. The retaining ring may be installed in a groove on the shaft, typically at the bottom end of the impeller stack. The impeller hub may be stacked above the retaining ring, wherein the retaining ring constrains the impeller from moving downward. The spacer may sit between the retaining ring and the 2-piece ring, allowing load transfer from the impeller to the shaft via this assembly. The diffuser may not be directly in contact with the retaining ring or spacer in this configuration.

FIG. 7 shows an example of an intelligent compression pump 700 with a retaining ring 702 and a gap 704 (e.g., clearance gap) in the shaft stack, according to one or more examples of the disclosure. The gap 704 between the retaining ring 606 and the 2-piece ring allows load transfer from the retaining ring 602 to the spacer 604 then to the two-piece ring. The 2-piece ring design 600 may be located at each stage of pump 700. intelligent compression pump 700 may have the impellers stacked on top of each other. In some embodiments, two or more pumps may be stacked on top of each other. In some embodiments, one or more impellers are configured to move along the shaft in the upward direction (e.g., to not lock at a top end of the pump shaft).

Intelligent compression pump 700 may operate in a first mode (e.g., compression mode) and/or a second mode (e.g., floater mode). Under normal operation, when the pump is operating under normal or high-speed conditions, and stage deflection is within the shaft lift range: the impellers may be stacked hub-to-hub and transmit downthrust through the shaft; the pump may behave like a compression pump; one or more impellers may be mechanically coupled through the shaft and transfer thrust to the protector thrust bearing. Under excessive deflection, the pump may operate in floater mode wherein: the top impellers begin to float-they lose contact with the shaft or thrust washer; only the thrust from the deflected stage is transferred to the adjacent diffuser, not the entire pump thrust. This behavior mimics a floater pump, where impellers self-adjust axially and absorb thrust locally. In the intelligent compression pump 700, the impellers may not be rigidly locked to the shaft at the top end. Instead, one or more of the impellers may be stacked hub-to-hub and secured at the bottom via a retaining ring and two-piece ring assembly. This may allow compression behavior when the shaft is fully engaged and floating behavior when deflection causes the impellers to lift off the shaft or thrust washer. So, the impeller hub may be partially constrained: mechanically coupled to the shaft through the stack and bottom stop and free to float at the top end when deflection exceeds shaft lift. The impellers may be stacked hub-to-hub and constrained at the bottom (e.g., by a retaining ring, spacer and/or two-piece ring), but not rigidly locked axially at both ends like in traditional compression pumps. The impellers (e.g., via the impeller hub) may be rotationally coupled to the shaft via keying or splines, and axially constrained at the bottom via the 2-piece ring design.

In compression pumps, impellers may be locked both rotationally and axially: rotationally via keying or splines, and axially via tight hub fit, hub-to-hub stacking, spacers (e.g., rings or sleeves that fill axial gaps), shaft shoulders, or retaining rings on both ends. This forms a rigid impeller stack that transmits all thrust through the shaft. In floater pumps, impellers may be keyed/splined for rotational locking. But they are free to float axially (e.g., no axial locking). Each impeller may handle its own thrust via local thrust pads or washers.

The intelligent compression pump 700 may comprise any of the features of compression and/or floater pumps. In the intelligent compression pump 700, impellers may be keyed/splined (e.g., comprise one or more keys or splines) for rotational locking. Axially, the intelligent compression pump 700 may be constrained at the bottom or the top, depending on orientation, (e.g., by a retaining ring, spacer, and/or two-piece ring design). The impellers in the intelligent compression pump 700 may not be locked at one end (e.g., the top), allowing conditional axial float under deflection. This may create a hybrid behavior: compression mode when the shaft is engaged, floater mode when deflection exceeds shaft lift. Under a given amount of downthrust, the shaft may move downward. Since the impeller is not locked at one end (e.g., the top), it remains in place or moves less appearing to float upward relative to the shaft. Intelligent compression pump 700512 may have one or more gaps between impeller hubs. In some embodiments, individual impellers within a pump or a stack of pumps may be mixed such that one or more are compression, one or more are floater, one or more are intelligent compression. For example, one or more upper impellers may have an intelligent compression design, while the remaining lower impellers are compression or floater design. In some embodiments the first and/or second and/or and/or fourth and/or fifth impeller have the intelligent compression pump design (e.g., 2-piece ring design on one end of the impeller/impeller hub and unconstrained on the other end of the impeller/impeller hub), while the remaining impellers below have a traditional compression design wherein the impeller is axially fixed to the shaft.

The impeller comprises a central hub configured to engage with the pump shaft via rotational locking features such as splines or keys. The impeller hub includes a first end (e.g., a bottom end) that is axially constrained by a mechanical stop, such as a retaining ring, spacer, or two-piece ring assembly. The opposite end of the impeller hub-referred to herein as the unconstrained end-is not rigidly fixed or axially locked to the shaft or any adjacent component.

The unconstrained end (e.g., a top end of the impeller hub) is free to move axially within a defined clearance range in response to dynamic operating conditions, such as shaft deflection, thermal expansion, or variable thrust loads. This axial freedom allows the impeller to enter a floater mode, wherein the impeller hub may lift off the shaft shoulder or thrust washer and self-adjust its axial position. The unconstrained end may intermittently contact a thrust washer or adjacent diffuser surface to absorb localized axial thrust, but it is not continuously engaged with any fixed axial stop.

The unconstrained end enables hybrid pump operation by allowing the impeller to behave as a compression element under normal shaft engagement and as a floater element under excessive deflection. This design reduces cumulative thrust transmission through the shaft and enhances stage- level load distribution.

Advantageously, the difference in magnitude of thrust load of an embodiment of the pump system described compared to a conventional compression type pump significantly reduces the wear rate of the pump, hence considerably improves and extends the operational run-life of an electronic submersible pump (ESP) string.

The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the disclosure. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the systems and methods described herein. The foregoing descriptions of specific examples are presented for purposes of illustration and description. They are not intended to be exhaustive of or to limit this disclosure to the precise forms described. Obviously, many modifications and variations are possible in view of the above teachings. The examples are shown and described in order to best explain the principles of this disclosure and practical applications, to thereby enable others skilled in the art to best utilize this disclosure and various examples with various modifications as are suited to the particular use contemplated. It is intended that the scope of this disclosure be defined by the claims and their equivalents below.