Patent Application
20240301775
The present disclosure generally relates to electric submersible pump (ESP) protectors or seal sections, and more particularly to protector configurations allowing for redundant shaft seals.
Various types of artificial lift equipment and methods are available, for example, electric submersible pumps (ESPs). An ESP includes multiple centrifugal pump stages mounted in series, each stage including a rotating impeller and a stationary diffuser mounted on a shaft, which is coupled to a motor. In use, the motor rotates the shaft, which in turn rotates the impellers within the diffusers. Well fluid flows into the lowest stage and passes through the first impeller, which centrifuges the fluid radially outward such that the fluid gains energy in the form of velocity. Upon exiting the impeller, the fluid flows into the associated diffuser, where fluid velocity is converted to pressure. As the fluid moves through the pump stages, the fluid incrementally gains pressure until the fluid has sufficient energy to travel to the well surface.
In some configurations, a protector for an electric submersible pump includes a shaft extending axially through the protector; at least one positive-sealing chamber disposed about the shaft; a shaft tube associated with the chamber, the shaft tube surrounding the shaft; and a body positioned axially at an end of the chamber, the protector configured to fluidly isolate a volume within the shaft tube from fluids inside and outside of the chamber.
The body can include a shaft seal about the shaft. The chamber can be or include an elastomer bag. The at least one positive-sealing chamber can include at least two positive-sealing chambers, and the body can be positioned axially between two consecutive positive-scaling chambers. The body can include a shaft seal about the shaft, and the consecutive positive-scaling chambers can be configured in parallel. Alternatively, the consecutive positive-sealing chambers can be configured in series with no shaft seal. The protector can include a shaft seal disposed axially between the positive-sealing chamber and a thrust bearing chamber.
The body can include a compensator configured to compensate for thermal expansion and/or contraction of oil within the shaft tube. The compensator can be or include an elastomer bag, an elastomer bellows, a metal bellows, a movable piston, a volume of compressible gas, or a column of fluid that is denser than well fluid. The protector can include a relief valve configured to relieve excess pressure in the shaft tube.
The protector can include a plurality of fluid pathways configured to fluidly isolate the volume within the shaft tube from the fluids inside and outside of the chamber into two separate hydraulic circuits. The positive-sealing chamber can be coupled to a bag frame, and two coaxial seals can be disposed between the bag frame and the body and configured to separate the volume within the shaft tube from the fluids inside and outside of the chamber.
In some configurations, a body for a protector of an electric submersible pump is configured to be positioned axially between two consecutive positive-sealing chambers of the protector and includes two fluidly isolated hydraulic circuits.
In some configurations, a protector includes such a body, a shaft, a plurality of positive-sealing chambers, a shaft tube associated with each chamber, each shaft tube surrounding the shaft, and a shaft seal associated with each body, wherein a first of the two fluidly isolated hydraulic circuits defines a volume partially bounded by the shaft, the shaft tube, and the shaft seal, and a second of the two fluidly isolated hydraulic circuits defines a volume inside and outside the chambers. The protector can include a compensator configured to compensate for thermal expansion and/or contraction of oil in the first of the two fluidly isolated hydraulic circuits. The compensator can be or include an elastomer bag, an elastomer bellows, a metal bellows, a movable piston, a volume of compressible gas, or a column of fluid that is denser than well fluid. The protector can include a relief valve configured to relieve excess pressure in the shaft tube. The positive-sealing chambers can be or include elastomer bags. The first and second fluidly isolated hydraulic circuits can be independent of relative rotational relationship between the positive-sealing chambers and the body.
The body can include a shaft seal and be configured to couple the two consecutive positive-sealing chambers in parallel. The body can be configured to couple the two consecutive positive-sealing chambers in series without including a shaft seal.
Certain embodiments, features, aspects, and advantages of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein.
In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. 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 are possible. This description is not to be taken in a limiting sense, but rather made merely for the purpose of describing general principles of the implementations. The scope of the described implementations should be ascertained with reference to the issued claims.
As used herein, the terms “connect”, “connection”, “connected”, “in connection with”, and “connecting” are used to mean “in direct connection with” or “in connection with via one or more elements”; and the term “set” is used to mean “one element” or “more than one element”. Further, the terms “couple”, “coupling”, “coupled”, “coupled together”, and “coupled with” are used to mean “directly coupled together” or “coupled together via one or more elements”. As used herein, the terms “up” and “down”; “upper” and “lower”; “top” and “bottom”; and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements. Commonly, these terms relate to a reference point at the surface from which drilling operations are initiated as being the top point and the total depth being the lowest point, wherein the well (e.g., wellbore, borehole) is vertical, horizontal or slanted relative to the surface.
Various types of artificial lift equipment and methods are available, for example, electric submersible pumps (ESP). As shown in the example embodiment of
The pump 112 includes multiple centrifugal pump stages mounted in series within a housing 230, as shown in
In use, well fluid flows into the first (lowest) stage of the ESP 110 and passes through an impeller 210, which centrifuges the fluid radially outward such that the fluid gains energy in the form of velocity. Upon exiting the impeller 210, the fluid makes a sharp turn to enter a diffuser 220, where the fluid's velocity is converted to pressure. The fluid then enters the next impeller 210 and diffuser 220 stage to repeat the process. As the fluid passes through the pump stages, the fluid incrementally gains pressure until the fluid has sufficient energy to travel to the well surface.
In use, the protector or seal section 115 compensates for thermal expansion and contraction of motor oil during on-off cycles and/or prevents or inhibits ingress of well fluids into the motor 116, which could cause electrical or mechanical failure of the motor 116. The protector 115 can have various configurations of chambers, for example, labyrinths (which operate via reverse gravity separation), dense barrier fluid, elastomer bags, and metal bellows. The length of each chamber is typically limited by the need to provide support to the shaft, for example, with radial bearing(s) in bodies between chambers. In cases in which the required volume of compensation can be accommodated in a single chamber, successive chambers in the protector 115 are typically configured in series to provide multiple layers of protection. In cases in which the required volume of compensation exceeds the capacity of a single chamber, successive chambers typically must be configured in parallel, such that their individual volumes act in combination. Parallel configurations are common in protectors 115 including elastomer bag and/or metal bellows chambers.
In a series configuration, an upper end of the protector bag is in communication with the shaft seal area, so the bags and shaft seals together form one fluid barrier and are dependent on each other. In a parallel configuration, the passageway from inside a lower bag to inside a next sequential upper bag is through the central bore, where the shaft seal would be located in a series configuration. Therefore, while there is a shaft seal in bodies between bags in a series configuration, there cannot be a functioning shaft seal in bodies between bags in a typical parallel configuration.
As redundant shaft seals are a critical line of defense against well fluid entry into the motor 116, the lack of shaft seals in a parallel configuration can disadvantageously decrease reliability. Additionally, the lowest body in the protector 115 cannot include a shaft seal if the chamber above it is in the form of a bag, because the bag must communicate to the thrust chamber via the central bore, which would be blocked if a shaft seal was present. Therefore, protectors 115 often include a labyrinth in the lower chamber, as a labyrinth allows for addition of a shaft seal in the lowest body. However, a labyrinth typically offers less protection from well fluid than a bag. Furthermore, a labyrinth just above the thrust bearing can trap gas that can be sucked down into the thrust bearing upon a system shutdown and cause bearing failure upon restart. When parallel chambers are required due to the required compensation volume, the protector 115 designer typically must choose between foregoing layers of protection (e.g., shaft seals) or adding another protector 115. However, more than two protectors is generally impractical due to, for example, cost and/or cumulative length shaft deflection.
A compensating shipping cap 306, with may include a bag, can be positioned adjacent or proximate an upper end 302 of the protector 115. The protector 115 can include a head 308, which may include a shaft seal, below the compensating shipping cap 306 and/or above the protector bags 310. The protector 115 includes a base 360 adjacent or proximate a lower end 304 of the protector 115. The protector 115 includes a thrust bearing chamber 350 positioned above and adjacent or proximate the base 360.
The example protector 115 illustrated in
Although the examples illustrated and described herein primarily show and describe protector 115 chambers in the form of bags, e.g., elastomer bags, various features as shown and described herein can also be applied to other types of protector 115 chambers, for example, metal bellows, pistons, or other positive compensator or positive-sealing chambers.
In protectors 115 according to the present disclosure, the hydraulic circuit of the bags 310 is separated or isolated, e.g., fluidly separated or isolated, from the hydraulic circuit of the shaft seals 325 and shaft tubes 370. This separation or isolation advantageously enables or allows for the addition of a shaft seal 325 in a parallel body 330 and/or in the lowest body or base 360, which can advantageously increase reliability. This separation or isolation also isolates the shaft seals 325 from leakage into the bags 310 and isolates the bags 310 from leakage into the shaft seal 325. In other words, leakage into a bag 310 cannot bypass a shaft seal 325 and vice versa, so the shaft seals 325 and bags 310 are each independent, redundant systems.
In typical protectors 115, for example in the configurations shown in
In contrast, the isolation of the volume inside the shaft tube 370 from the fluids inside and outside the bags 310, for example in the configurations illustrated in
In some configurations, for example as shown in
The compensator 500 is connected to another component, such as the body 320, 330, bag frame, shaft, and/or shaft tube 370. For example, the compensator 500 can be connected to the body 320, 330 and/or shaft tube 370 internally or externally to the body 320, 330 and/or shaft tube 370, and either directly or via a passageway, e.g., a fluid passageway. The compensator 500 can be connector to the other component via, for example, threads, threaded fasteners, interference fit, male-female seal, face seal, metal melting, adhesive, or entrapment between other components. If connected via a passageway, the passageway may pass through or between various protector components, such as the body, bag frame, shaft tube, shaft, e.g., a hollow shaft, or housing. For example, in the configurations of
In some configurations, the body 320 or 330 includes a relief valve 390 (separate from relief valve 380 shown in
In some configurations, for example in protectors 115 having a smaller diameter and more limited radial space, the compensator 500 and/or relief valve 390 can be located above or below the body 320 or 330, for example, in an area between the body 320 or 330 and lower bag 310b, inside the bag 310, or between the bag 310 and the outer housing 301. In some configurations, for example in protectors 115 having a larger diameter, the compensator 500 and/or relief valve 390 can be contained, e.g., fully contained, partially contained, or substantially contained, within the body 320 or 330. Positioning of the compensator 500 and/or relief valve 390 fully or at least partially within the body 320, 330 can reduce or minimize the overall length of the assembly. In some configurations, the relief valve 390 can be located in a hollow bore of the shaft, which communicates to other regions.
In use, the compensator 500 and/or relief valve 390 can equalize pressure among various locations, including: the wellbore; the shaft tube 370 above the subject shaft tube 370, the shaft tube 370 below the subject shaft tube 370, the inside of the bag 310 above the subject shaft tube 370, the outside of the bag 310 above the subject shaft tube 370, the inside of the bag 310 surrounding the subject shaft tube 370, the outside of the bag 310 surrounding the subject shaft tube 370, the inside of the bag 310 below the subject shaft tube 370, the outside of the bag 310 below the subject shaft tube 370, the motor below it, and/or a sealed chamber. Pressure equalization can be selected to reduce or minimize the overall risk of well fluid entry into the motor. In some configurations the compensator 500 and relief valve 390 equalize pressure with the inside of the bag 310 below, or in the case of the lowest chamber, with the motor below it. This reduces or minimizes the chance of contamination by increasing or maximizing the available volume of the cleanest oil downstream. Such contamination could block expansion of the compensator 500 or inhibit full closure of the relief valve 390.
In the configurations of
In the parallel body 330 in
In the configurations illustrated in
In the series body 320 in
In some configurations, the body 320 or 330 includes an “S” or seal port leading to the region just below the shaft seal 325 and an “F” or fill port leading to the region just above the shaft seal 325. These ports can be used for vacuum filling the shaft tube 370 with oil, for example, with vacuum pulled on the S port and oil pumped into the F port. As the shaft tube 370 is isolated from the bags 310, the S and F ports may not be in communication with the pathways 442 or 444 that extend through the body 320 or 330 in series or parallel configuration, respectively.
Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and/or within less than 0.01% of the stated amount. As another example, in certain embodiments, the terms “generally parallel” and “substantially parallel” or “generally perpendicular” and “substantially perpendicular” refer to a value, amount, or characteristic that departs from exactly parallel or perpendicular, respectively, by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.
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. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments described may be made and still fall within the scope of the disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above.
Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. The present application is a continuation of U.S. patent application Ser. No. 17/995,200, which is s the National Stage of International Application No. PCT/US2021/025150 filed Mar. 31, 2021, which claims the priority benefit of U.S. Provisional Application No. 63/003,246 filed Mar. 31, 2020, the entirety of each is incorporated by reference herein and should be considered part of this specification.
| Number | Date | Country | |
|---|---|---|---|
| 63003246 | Mar 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17995200 | Sep 2022 | US |
| Child | 18668969 | US |
