1. Field of the Invention
This invention relates in general to a subterranean connector for use in a wellbore. More particularly, the present invention is directed to a connector used to provide power to a submersible motor. Yet more particularly, the present invention provides a electrical submersible pump connector configured to be pressure compensated.
2. Description of the Related Art
A common type of electrical submersible pump comprises a centrifugal pump suspended on a string of tubing within a casing of the well. The pump is driven by a downhole electrical motor, normally a three-phase AC type. A power line extends from a power source at the surface alongside the tubing to the motor to supply power.
Typically the power line is made up of two sections, an external motor lead (external to the motor) and a power cable. The external motor lead has a plug on its lower end known as a “pothead” that secures to a receptacle known as a “pothole” at the upper end of the electrical motor. The external motor lead typically has three conductors that are insulated and located within a single elastomeric jacket that is extruded around the assembled insulated conductors. Metallic outer armor may wrap around the jacket of the external motor lead to avoid damage to the motor lead while running the pump assembly into the well. The external motor lead extends upward beyond the pump, for example, from 10 to 80 ft. The total of the external motor lead and pothead is known as the motor lead extension (MLE). The lead could exceed 80 ft or be shorter than 10 ft depending on the application. A splice connects the external motor lead to the power cable. The external motor lead is flat and smaller in dimension than the power cable so that it can pass between the pump assembly and the casing.
The power cable typically comprises three conductors, each having one or more layers of insulation. An elastomeric jacket is usually extruded over the assembled conductors. In some cases, the insulated conductors are encased in lead. The insulated conductors are arranged either in a flat side-by-side configuration, or in a round configuration spaced 120 degrees apart from each other relative to a longitudinal axis of the power cable. A metallic armor is typically wrapped around the jacket to form the exterior of the power cable.
In some wells, the formation pressures are quite high and can vary, causing a significant differential in pressure between the internal pressure of the motor and the internal pressure of the pothead and/or pothead connector. Therefore, it would be beneficial to have a motor electrical connection design that is operable to compensate for internal differential pressure between the connector in the motor.
In view of the foregoing, various embodiments of the present invention advantageously provide a sealed motor electrical connection and methods of employing the sealed motor electrical connection.
More specifically, an example of an embodiment of a motor lead extension-to-motor lead connector apparatus includes a hermetically sealed pothead connection positioned in a chamber forming an independent dielectric oil reservoir. According to the exemplary configuration, this oil reservoir is pressure compensated by a metal bellow or similar device to either the internal motor or the well annulus pressure. According to the exemplary configuration, the chamber can be packaged in a couple of different configurations relative to the motor. These exemplary configurations strive to support various objectives including moving the 3 connection points to positions as far away from each other as possible to thereby increase the tracking distances. One option is to make 3 separate chambers that could be mounted on the outer diameter (OD) of the head of the motor spaced up to 120 degrees apart. Another option is to package each of these 3 connection points in a separate device that could be placed between the motor head and seal section to accommodate electrical connections and pressure compensation elements. Another option is to package each of these three connection points inside the “pothead” of a motor lead extension (MLE).
According to an exemplary configuration, this chamber can be pressure compensated and isolated from the motor oil and well fluid in order to serve as a controlled environment where the connection from the power cable (i.e., MLE) to the motor's lead wires will occur. According to an exemplary configuration, the motor-side of the chamber can use compression fittings or the like to seal against the stator lead wires which extends through the motor housing. The compression fitting will isolate the dielectric motor oil and keep it from entering into the connector chamber. According to an exemplary configuration, the female side of a plug-in connection is located on the opposite side of the connector chamber. This can be of similar construction to a wet-mate connector.
According to the exemplary configuration, a shuttle pin will shift inside the connector to engage the male plug to the female receptacle. According to this configuration, when a connection is made, this spring-loaded shuttle pin will be wiped through two sealing glands which house independent dielectric oil chambers. Advantageously, the separate dielectric oil chambers can use two different densities of dielectric oil or grease in the chambers to prevent cross contamination therebetween. It should be noted that this connection point is where non-insulated points of high electrical potential reside. The connector apparatus advantageously provides a means to keep this area in a state of high dielectric strength and physically isolated to prevent electrical shorts to either of the adjacent phases and to prevent the connectors from seeking ground.
According to an exemplary configuration, the conductors of the MLE are contained in steel tubing and the ends are sealed with compression fittings and terminated to a male plug (e.g., modified pothead). This plug can have a typical spin collar (like a feed-thru penetrator) that threads onto the housing of the female portion of the connector.
So that the manner in which the features and advantages of the invention, as well as others which will become apparent, may be understood in more detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only various embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it may include other effective embodiments as well.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. Prime notation, if used, indicates similar elements in alternative embodiments.
According to the exemplary configuration, at least one, but more preferably two barrier oil chambers 51, 53, are contained within the housing 41 and provide two independent isolated dielectric oil reservoirs. As shown in the figure, barrier oil chamber 51 surrounds and is sealed about a female terminal 55 at the end of the external portion 47 of the motor lead 45 to contain the female terminal 55 in its isolated dielectric oil reservoir. The barrier oil chamber 53 surrounds the barrier oil chamber 51 surrounding the female terminal 55 to provide a second layer of isolation within its isolated dielectric oil reservoir. Note, although each of the chambers are described as containing a dielectric oil, one of ordinary skill in the art would recognize that other dielectric fluids can be utilized which would not necessarily be classified as an oil to include, but not limited to dielectric greases.
According to the exemplary configuration, each dielectric oil reservoir is pressure compensated by a pressure compensation device such as, for example, a metal bellow or bellows 61, 63, or other device having a similar function, such as, for example, a balancing piston or pistons, which extend into secondary dielectric oil reservoirs 65, 67. Dielectric oil surrounding the bellows 61, 63 is in fluid communication with the barrier oil chambers 51, 53 through passageways 69, 70. As shown in
Alternatively, as shown in
According to an exemplary configuration, each of chambers 51, 53, are pressure compensated and isolated from the motor oil 79 and well fluid 79′ in order to serve as a controlled environment where the connection from motor lead extension 23 to the motor's lead wires 47 will occur. According to an exemplary configuration, in order to prevent contamination of chamber 53 by motor oil 79 as a result of passage of the portion 47 of motor lead 45 into the chamber 53, compression fitting 81 or the like can be used to seal against the motor lead 45. The compression fitting 81, particularly when employed in conjunction with an I-block feed through 83, will function to isolate the motor oil 79 and keep it from entering into the connector chamber 53.
According to an exemplary configuration, a plug-in connection, which can be, for example, of similar construction to a wet-mate connector, is located on the top (distal) portion of the female motor connector 31. Referring to
Referring again to
Referring to
It should be noted that this male pin-shuttle pin connection point is where non-insulated points of high electrical potential reside. According to an exemplary configuration, the connector apparatus 22 provides a means to keep this area in a state of high dielectric strength and physically isolated to prevent electrical shorts to either adjacent phases and to prevent the connectors from seeking ground.
Advantageously, an embodiment of the present invention includes an embodiment of the apparatus 22 for connecting a motor lead extension 23 to a motor lead 45 that incorporates a hermetically sealed pothead connection in an independent dielectric oil reservoir 51, 53. This oil reservoir 51, 53, can be pressure compensated by a metal bellow 61, 63 (or similar device) to either the internal motor or well annulus pressure. This chamber 51, 53, can advantageously be packaged in a couple of different configurations relative to the motor 16. A common objective can include a goal of moving the 3 electrical connection points to connect to the motor 16 at a location as far away from each other as possible to increase the tracking distances. One option, according to an embodiment, is to make 3 separate female connection points 31 (see, e.g.,
Referring to
With reference to a single female motor connector 131, on the other side of the chamber 53 is where the female connection point 113 of a plug-in connection 131 is located. This can be of similar construction to a wet-mate connector where a shuttle pin 93 shifts inside the connector to engage the male plug/extension connector 33 to the female connection point 113 of the female motor connector 131. According to this embodiment, when a connection is made, a spring-loaded shuttle pin 93 is wiped through two sealing glands 117, 119, which house independent dielectric oil chambers 51, 53.
According to an embodiment, the chambers 51, 53, can use two different densities of dielectric oil or grease to prevent cross contamination. This electrical connection point (female terminal 55 with pin 93 engaged by pin 91) is where there are non-insulated points of high electrical potential reside. Advantageously, this configuration provides a means to keep this area in a state of high dielectric strength and physically isolated to prevent electrical shorts to either adjacent phases or to prevent the connectors from seeking ground. Note, this configuration can include the various configurations of pressure compensation devices or bellows 61, 63 and exchange conduits 71, 71′, 73, 73′ shown and described with respect to
According to an embodiment, the conductor 101 of the motor lead extension 23 is contained in steel tubing 103 and the ends can be sealed with compression fitting 105 and terminated to a male plug 107 encircled with a compression plate 109. This plug 107 can have a typical spin collar 111 (e.g., similar to a feed-thru penetrator) that threads onto the female connection point 113 on the housing 141.
Referring to
Primarily referring to
With reference to a single female motor connection, on the other side of the chamber 51 is where the female connection port 232 and associated connection components are located. This can be of similar construction to a wet-mate connector where a shuttle pin 93 shifts inside the connector to engage one of the plurality of pins 91 of an external motor lead extension connector apparatus 233 (
According to an embodiment, the chambers 51, 53, can use two different densities of dielectric oil or grease to prevent cross contamination. This electrical connection point (female terminal 55 with pin 93 engaged by pin 91) is where there are non-insulated points of high electrical potential reside. Advantageously, this configuration provides a means to keep this area in a state of high dielectric strength and physically isolated to prevent electrical shorts to either adjacent phases or to prevent the connectors from seeking ground. Note, this configuration can include the various configurations of pressure compensation devices or bellows 61, 63 and exchange conduits 71, 71′, 73, 73′ shown and described with respect to
Primarily referring to
The motor lead extension connector apparatus 233 can include an annular seal circumscribing the entire set of pins 91 or can have individual seals circumscribing each of the pins 91 and can be sealed to a faceplate 234 surrounding each of the set of ports 232. A set of bolts or other fasteners 223 extend through a set of apertures 224 in a pair of flanges 225. The bolts or other fasteners 223 engage a corresponding set of apertures 226 in an outer surface 235 of the motorhead 24. Note, other connection and sealing configurations are within the scope of the present invention.
Referring primarily to
The steps also include providing a female motor connector 31 including a housing 41 containing chambers 51, 53 filled with dielectric oil. The female motor connector 31 is configured to connect to the motor housing 37. Chambers 51, 53 are configured to envelop and contain the portion 47 of the motor lead 45 extending through the motor housing 37.
The steps correspondingly include connecting the female motor connector 31 to an outer surface portion of the motor housing 37 surrounding the portion 47 of the motor lead 45 extending through the motor housing 37 to thereby isolate the portion 47 of the motor lead 45 within the chamber 43.
According to an exemplary embodiment, the steps can also include positioning a pressure compensation device 61, 63 at least substantially within the housing 41 of the female motor connector 31. The pressure compensation device 61, 63 can take the form of bellows which can inflate or deflate in response to fluid entering or exiting the device.
According to the exemplary configuration shown in
According to the exemplary configuration, the steps can also include positioning a first barrier oil chamber 53 within a housing 41 and positioning a second barrier oil chamber 51 within the first barrier oil chamber 53 to receive and contain the female terminal 55 on the distal-most end of the portion 47 of the motor lead 45 extending through the housing 37 of the motor 16. In the exemplary configuration, the first barrier oil chamber 53 spatially surrounds an contains barrier oil chamber 51.
The pressure compensation device 61 is further positioned to interface with the barrier oil chamber 51 so that, using the bellows example, when the device inflates, fluid pressure is applied to the dielectric fluid contained within barrier oil chamber 51. Similarly, the pressure compensation device 63 can be positioned to interface with barrier oil chamber 53 so that, using the bellows example, when the device inflates, fluid pressure is applied to the dielectric fluid contained within barrier oil chamber 53. The opposite, is of course true for when the devices 61, 63 are deflated due to a higher pressure exerted on the external surfaces of the device 61, 63, than that applied internally via either the motor oil 79 or the well fluid 79′.
According to the exemplary embodiment, the steps also include positioning a shuttle pin 93 within the housing 41 and configuring the shuttle pin 93 to slidably extend through the first and second barrier oil chambers 51, 53 to engage the female terminal 55 in response to engagement by a male pin 91. Correspondingly, the steps also can include connecting a male motor lead extension connector 33 to a distal portion of the female motor connector 31, engaging the shuttle pin 93 with the male pin 91 of the male motor lead extension connector 33 as shown in
Various embodiments of the present invention provide several advantages. For example, according to an embodiment of the present invention the physical conductor junction between the electrical power cable and the motor's lead wires are located in a protected chamber located on, in, or near the motor head. Advantageously, this chamber is isolated from the well fluids and the motor oil preventing contamination from internal and external environments. This chamber is also pressure compensated to the well bore pressure through a metal bellows or similar system, for example. According to an embodiment, this apparatus can incorporate a chamber that uses compression fittings or something similar to seal against stator lead wires, which isolates the dielectric motor oil and the connection system. Advantageously, this chamber can facilitate a wet-mate style, dual dielectric oil sealing electrical connection system. When the male and female connections are plugged together, the male connection engages a spring loaded shuttle pin which is wiped through two oil filled chambers to make the connection with a female terminal. Advantageously, the separate chambers can use two different densities of dielectric oil or grease to prevent cross contamination.
According to an embodiment, the conductors of the motor lead extension are contained in steel tubing and the ends are sealed with compression fittings and terminated to the male plug/connector. This plug can have a typical spin collar (like a feed-thru penetrator) that threads onto the female connection point on the chamber. This chamber can house the connection points of the 3 phases as far away from each other as possible. The chamber can alternatively be 3 separate chambers mounted on the outer diameter of head of the motor up to 120 degrees apart. Another option includes the incorporation of a manifold placed between the motor head and seal to accommodate connection separation and pressure compensation.
In the drawings and specification, there have been disclosed a typical preferred embodiment of the invention, and although specific terms are employed, the terms are used in a descriptive sense only and not for purposes of limitation. The invention has been described in considerable detail with specific reference to these illustrated embodiments. It will be apparent, however, that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification.
This application is a non-provisional patent application of and claims priority to and the benefit of U.S. Patent App. No. 61/522,555, filed on Aug. 11, 2011, titled “Hermetically Sealed Motor Electrical Connection and Related Methods,” incorporated by reference in its entirety.
Number | Date | Country | |
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61522555 | Aug 2011 | US |