Patent Description:
In oil and gas, subsea operations may be performed in waters offshore at great depths. In order to recover hydrocarbons from a well, any number of electrical systems may be deployed on the seabed to perform subsea operations. Many of these electrical systems need high-reliability power grids and power control units located on the seabed, offshore rig, and/or buoyant devices to power various devices. Power systems play a major role in providing the required and reliable power to the various electrical systems. But, there are many challenges for deploying power components under the seabed such as the requirements of power system components operating in subsea environment, use of electronics for efficient transmission of power from the offshore platform or from the shore to the subsea electrical loads, variable speed drive systems, and research areas related to power electronics for subsea electrical systems.

In conventional methods, power is provided from external sources to the subsea devices via cable conductors to submerged process control equipment, pumps and compressors, transformers, motors, and other electrically operated equipment. As these components are disposed subsea and are typically enclosed and protected by water-proof pressure vessels, power is provided by means of a cable termination and connector, which may be an electrical penetrator, designed to penetrate and provide power through a subsea tree.

As described above, the installation and operation of subsea electrical systems have various challenges. Pressure increases about <NUM> MPa (equals <NUM> bar, which is about <NUM> PSI) for every <NUM> depth in the ocean, and thus, for electrical systems needing to be located at a water depth of about <NUM>, the electrical systems encounters about <NUM> MPa (<NUM> bar) pressure. At these depths, all the electrical components have to be designed and qualified to withstand high pressures. Additionally, sea water is a conductor and corrosive, hence proper isolation between the electrical equipment and the sea water needs to be provided. As the equipment is located at depths of up to <NUM>,<NUM>, in the event of fault, maintenance will be a challenge and will not be possible without bringing the equipment to the surface. However, bringing the equipment to surface is expensive and can result in long production outages. In some instances, the reliability of the equipment for the subsea applications has to be designed for more than <NUM> years.

Typically, electrical power for the subsea operations is generated in two different ways, one being offshore power generation and the other is onshore generating station. In the case of offshore power generation, gas turbine driven generators may be installed on the platforms. In the case of onshore generating stations, subsea devices such as electric submergible pumps ("ESP") and compressors are located very far from the onshore generating stations, it requires a long tieback power transmission system. Further, using high power high voltage AC transmission systems may minimize the power losses, and the reactive power due to the large capacitance of the power umbilical. In addition, the long distance high power and high voltage transmission/distribution require strong power cables with good insulation capability. The power umbilical can be fully electric or multiplexed wherein both electrical and hydraulic lines are combined to feed power from the power generator to the subsea device.

<CIT> discloses an underwater electrical connector comprising male and female parts which are brought together to make an electrical connection. The female part includes first, second and third closed chambers containing electrically insulating media, the second chamber being located within the first, and the third chamber being located within the second. An electrically insulating shuttle piston extends through a contact socket disposed in the third chamber and through respective aligned openings of the three chambers. The shuttle piston is arranged to be urged back by a contact pin of the male part of the connector during insertion thereof such that the contact pin is received and directly engaged by the contact socket in the third chamber to effect the electrical connection.

<CIT> discloses an electrical connector for use in subsea applications comprising a receptacle component and a plug component. The receptacle component includes at least one, and typically three, fluted insulated male contact pins, each in an isolation tube containing dielectric oil. The receptacle component may also include an oil filled wiper system to provide oil to the pins - the fluting allows the oil to pass the pins. The pin may also have a cone seal. The plug component may contain a release mechanism.

In one aspect, the embodiments disclosed herein relate to an electrical feedthrough assembly having a lower assembly having a first end and a second end. The lower assembly may include an outer body with a lower housing and an upper housing disposed within a bore of the outer body and a first conductor extending from the lower housing to the upper housing, wherein at least one portion of the first conductor is enclosed in a first insulator. Additionally, the lower housing extends axial outward from the outer body to form the first end and the upper housing extends axial outward from the outer body to form the second end. Further, the electrical feedthrough assembly may have an upper assembly having body extending from a first end to a second end. The second body may include a pin end at the first end and the pin end is inserted into an opening of the second end of the lower assembly; a second conductor disposed within the body with at least one portion of the second conductor is enclosed in a second insulator; and a chamber within the body to hold the first conductor. Furthermore, the second conductor is conductively connected to the first conductor and a length of the first conductor is in contact with an electrical contact of the upper assembly.

Other aspects and advantages will be apparent from the following description and the appended claims. The claimed invention is defined in the independent claim of the appended claims.

Embodiments of the present disclosure will now be described in detail with reference to the accompanying Figures. Like elements in the various figures may be denoted by like reference numerals for consistency. Further, in the following detailed description of embodiments of the present disclosure, numerous specific details are set forth in order to provide a more thorough understanding of the claimed subject matter. However, it will be apparent to one of ordinary skill in the art that the embodiments disclosed herein may be practiced without these specific details. Additionally, it will be apparent to one of ordinary skill in the art that the scale of the elements presented in the accompanying Figures may vary without departing from the scope of the present disclosure.

As used herein, the term "coupled" or "coupled to" or "connected" or "connected to" "attached" or "attached to" may indicate establishing either a direct or indirect connection, and is not limited to either unless expressly referenced as such. In addition, as used herein, the terms "upper" and "lower" are merely used to indicate relative position and may change depending on orientation, and are not limited to either unless expressly referenced as such. Wherever possible, like or identical reference numerals are used in the figures to identify common or the same elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale for purposes of clarification. In addition, any terms designating tree or tubing head (i.e., any wellheads or tubing hanger) at a rig type (i.e., any land rig or offshore rig) should not be deemed to limit the scope of the disclosure. As used herein, fluids may refer to slurries, liquids, gases, and/or mixtures thereof. It is to be further understood that the various embodiments described herein may be used in various stages of a well, such as rig site preparation, drilling, completion, abandonment etc., and in other environments, such as work-over rigs, fracking installation, well-testing installation, oil and gas production installation, without departing from the scope of the present disclosure. It is recognized by the different embodiments described herein that a tree or tubing head plays a valuable and useful role in the life of a well. Further, it is recognized that electrical feedthrough assembly configuration and arrangement of components for providing electrical power to subsea devices according to one or more embodiments described herein may provide a cost effective alternative to conventional systems. The embodiments are described merely as examples of useful applications, which are not limited to any specific details of the embodiments herein.

In one aspect, embodiments disclosed herein relate to an electrical feedthrough assembly, such as electrical conductor that may be used to provide power to subsea devices, for example. The electrical feedthrough assembly may also be interchangeably referred to as an electrical penetrator assembly in the present disclosure. According to embodiments of the present disclosure, the electrical feedthrough assembly is an apparatus that may include a lower assembly and an upper assembly coupled together. In a non-limiting example, a pin end of the upper assembly is inserted into an opening of the lower assembly to conductively connect a conductor of the lower assembly to a conductor of the upper assembly. One skilled in the art will appreciate that by conductively connecting the conductor of the lower assembly to the conductor of the upper assembly, power is able to be provided through the electrical feedthrough assembly.

Referring to <FIG> illustrates wellhead <NUM> in accordance with one or more embodiments of the prior art. Wellheads are well known in the art, and thus, a brief overview is given to help provide a general view of the embodiments disclosed herein. The wellhead <NUM> includes a tubing head <NUM> disposed on the wellhead <NUM>. Additionally, the tubing head <NUM> contains a tubing hanger assembly <NUM> for engaging down hole equipment (not shown). Furthermore, the wellhead and the tubing head <NUM> may include a port <NUM> to perform various wellbore and annulus operations. One with ordinary skill in the art would understand that <FIG> illustrates one example of a wellhead; however, the wellhead <NUM> may take any form (i.e., number of components, shape, or size) known in the art without departing from the scope of the present disclosure.

Now referring to <FIG>, in one or more embodiments, <FIG> illustrates a cross-sectional view of the lower assembly <NUM> of an electrical feedthrough assembly (See <FIG>) in accordance with the present disclosure. The lower assembly <NUM> may include an outer body <NUM> with a bore <NUM>, such as a metal sub. In some embodiments, a lower housing <NUM> and an upper housing <NUM> may be disposed in the bore <NUM>. The lower housing <NUM> and the upper housing <NUM> may be made from metal. It is further envisioned that a lower end <NUM> of the lower housing <NUM> and an upper end <NUM> of the upper housing <NUM> may extend outside the bore <NUM> to form a first end <NUM> and a second end <NUM> of the lower assembly <NUM>, respectively. Furthermore, a first full-metal-jacket ("FMJ") connector <NUM> may be inserted into an opening <NUM> at a first end <NUM> of the lower housing <NUM>. In a non-limiting example, the first FMJ connector <NUM> may be a dual redundant metal-to-metal seal with multiple fittings such as the FMJ connector by Halliburton. In some embodiments, an opening <NUM> of the upper housing <NUM> may be exposed to a surrounding environment. In addition, an upper end <NUM> of the lower housing <NUM> may be coupled to a lower end <NUM> of the upper housing <NUM>. Further, the lower end <NUM> of the upper housing <NUM> may be threaded onto an outer surface <NUM> to connect to threads <NUM> in the bore <NUM>. It is further envisioned that the upper housing <NUM> may have protrusions <NUM> extending outwardly to land on an inner load shoulder <NUM> of the outer body <NUM>.

Still referring to <FIG>, in one or more embodiments, an electrical penetrator <NUM> may be disposed at the upper end <NUM> of the lower housing <NUM>. In a non-limiting example, the electrical penetrator <NUM> may include optics or ceramic to enable electrical transmission. Additionally, a metal-to-metal seal <NUM> may be inserted between the electrical penetrator <NUM> and the lower housing <NUM>. As further shown in <FIG>, the conductor <NUM> may extend a length of the lower assembly <NUM> to extend past the first end <NUM> into the tubing hanger assembly and connect to subsea devices. In a non-limiting example, the conductor <NUM> may be a wire or a shaft made of a material consisting of copper, gold, silver, aluminum, nickel-cobalt or any combinations thereof. It is further envisioned that the conductor <NUM> may have the conductor connector <NUM> attached thereof in the upper housing <NUM>. One skilled in the art will appreciate how the conductor <NUM> may have an insulator <NUM>, such as a polyether ether ketone ("PEEK") molding, surrounding a length of the conductor <NUM> to environmentally isolate the conductor <NUM>. Further, glass bodies (133a, 133b) may be disposed around portions of the conductor <NUM> and a glass-to-metal seals <NUM> may be inserted between the glass bodies (133a, 133b) and metal housings (e.g., the electrical penetrator <NUM>). While it is noted that <FIG> shows two glass bodies (133a, 133b), one of skill in the art would understand that this is merely a non-limiting example and any number of glass bodies may be used without departing from the present scope of the disclosure.

Now referring to <FIG>, in one or more embodiments, <FIG> illustrates a cross-sectional view of the upper assembly <NUM> of the electrical feedthrough assembly (See <FIG>) in accordance with the present disclosure. The upper assembly <NUM> may be a first body <NUM> coupled to a second body <NUM> extending from a first end <NUM> to a second end <NUM>. It is further envisioned that the second body <NUM> may be welded at a weld point <NUM> to the first body <NUM>. In a non-limiting example, a shoulder <NUM> of the second body <NUM> lands on a load shoulder <NUM> of the first body <NUM>. Further, the first body <NUM> may be made from PEEK molding and the second body <NUM> may be made from a metal. Furthermore, a second full-metal-jacket ("FMJ") connector <NUM> may be inserted into an opening <NUM> of the upper assembly <NUM> at the second end <NUM> to be connected the subsea tree connector of a subsea tree. The second FMJ connector <NUM> may be the same as the first FMJ connector <NUM>. Additionally, within the first body <NUM>, a chamber <NUM> includes an opening <NUM> at the first end <NUM>. One skilled in the art will appreciate how the chamber <NUM> may be any length and width without departing from the scope of disclosure. In a non-limiting example, the chamber <NUM> may have a port <NUM> in fluid communication with a surrounding environment. While it is noted that <FIG> illustrates the port <NUM> at an upper end of the chamber <NUM>, this is merely for example purposes only and the port <NUM> may be at any portion of the chamber <NUM> without departing from the scope of disclosure. Furthermore, grease <NUM> is applied within the chamber <NUM>. It is further envisioned that the port may have a valve to contain or release fluids from the surrounding environment within the chambers. By having the chamber <NUM>, when a pin end <NUM> of the upper assembly <NUM> is inserted into the opening <NUM> of the lower assembly <NUM> (see <FIG>), the conductor <NUM> (see <FIG>) of the lower assembly extends past the pin end <NUM> to sit in the chamber <NUM>. Additionally, the chamber <NUM> may also include elastomer wiper seals <NUM> to seal the conductor of the lower assembly within the chamber <NUM>. When the conductor of the lower assembly is within the chamber <NUM>, the conductor of the lower assembly may contact a first electrical contact 136a, which is connected to a second electrical contact 136b via a wire <NUM>. Further, the second electrical contact 136b is conductively connected to a conductor <NUM>. In a non-limiting example, the conductor <NUM> travels through an upper connector <NUM> to contact the second electrical contact 136b. One skilled in the art will appreciate how a length of the conductor <NUM> may be surrounded by glass bodies <NUM>.

Now referring to <FIG>, in one or more embodiments, an electrical feedthrough assembly <NUM> in accordance with the present disclosure is illustrated. The electrical feedthrough assembly <NUM> may include the lower assembly <NUM> and the upper assembly <NUM> coupled together, as described in <FIG> and <FIG>. The lower assembly <NUM> may be connected to the tubing hanger assembly by landing a first shoulder <NUM> of the lower assembly <NUM> on a shoulder of the tubing hanger assembly. It is further envisioned that the first FMJ connector <NUM> may be used to couple the first end <NUM> of the lower assembly <NUM> to a tubing hanger connector of the tubing hanger assembly. In some embodiments, the second FMJ connector <NUM> may be used to couple the second end <NUM> of the upper assembly <NUM> to a subsea tree connector of a subsea tree.

In one or more embodiments, the upper assembly <NUM> is lowered (see arrow <NUM>) into the lower assembly <NUM> such that a portion of the upper assembly <NUM> is within the lower assembly <NUM>. In a non-limiting example, the pin end <NUM> of the upper assembly <NUM> is inserted into the opening <NUM> of the lower assembly <NUM> such that a conductor <NUM> of the lower assembly <NUM> is conductively connected to the conductor <NUM> of the upper assembly <NUM>. It is further envisioned that the upper assembly <NUM> may include a plurality of electrical contacts (136a, 136b). While it is noted that <FIG> shows two electrical contacts (136a, 136b), one of skill in the art would understand that this is merely a non-limiting example and any number of electrical contacts may be used without departing from the present scope of the disclosure. In a non-limiting example, once the upper assembly <NUM> is coupled to the lower assembly <NUM>, the conductor <NUM> enters the chamber <NUM> of upper assembly <NUM> such that the first electrical contact 136a of the upper assembly <NUM> may contact a conductor connector <NUM> of the conductor <NUM> of the lower assembly <NUM>. In addition, the wire <NUM> connects the first electrical contact 136a to the second electrical contact 136b in contact with the conductor <NUM> of the upper assembly <NUM>. One skilled in the art will appreciate that by coupling the lower assembly <NUM> to the upper assembly <NUM> and having the electrical contacts (136a, 136b) conductively connecting each of the conductors (<NUM>, <NUM>), a continuous conductor is formed within the electrical feedthrough assembly <NUM>. With the continuous conductor <NUM> being formed, power may be provided through the electrical feedthrough assembly <NUM>. Further, the conductor <NUM> extends out from the upper assembly <NUM> to be attached to a power source.

Electrical feedthrough assemblies, according to embodiments herein, are apparatuses that include multiple conductors within a lower assembly and upper assembly, which may include a chamber with grease in upper assembly to compensate for motion and thermal expansion, and may include no environment compressible bladders installed within the multiple components that are arranged in a certain layout and contained within the electrical feedthrough assembly. The elimination of environment compressible bladders and the need for multiple fluids in the electrical feedthrough assembly significantly improves the operational safety, reliability, and longevity during drilling, completions, production, and work-over operations, while providing continuous power through the electrical feedthrough assembly. Further, a pin end of the upper assembly is inserted into an opening of the lower assembly to conductively connect a conductor of the lower assembly to a conductor of the upper assembly. In addition, one or more glass-to-metal seals and metal-to-metal seals, along with PEEK molding, may be used to environmentally isolate the conductors of the electrical feedthrough assembly. Furthermore, other instruments and devices, including without limitation, sensors and various valves may be incorporated within the electrical feedthrough assembly.

Conventional electrical feedthrough devices for subsea power distribution in the oil and gas industry are typically isolated conductors with various fluid profiles within each bladder of said conventional electrical feedthrough devices. Conventional methods may include an extensive layout and arrangement to ensure the conductors may be properly isolated and effective within said conventional electrical feedthrough devices. In some instances, conventional electrical feedthrough devices are manufactured to include multiple slots and chambers used to hold the bladders with various fluid profiles and an apparatus to the various fluid profiles do not mix. Such conventional electrical feedthrough devices may be more expensive to manufacture because of the extra machining needed to account for the various fluid profiles. Further, the use of bladders with various fluid profiles may increase the potential for gas and cycling build-up within the conventional electrical feedthrough devices as well as of leak paths to the environment. Additionally, conventional methods merely use elastomer seals which may cause the conventional electrical feedthrough devices to consistently fail an ohms test. This additional need for bladders with various fluid profiles and elastomer seals, increases the number of leak paths, adds to manufacturing and installation costs, and decreases the operational safety. Furthermore, conventional electrical feedthrough devices are designed to have the equipment in the subsea applications for more than <NUM> years.

The electrical feedthrough assembly is often used for assisting in providing power and electricity to well devices. Examples of the electrical feedthrough assembly may be used for drilling, completion applications, including natural flow, gas lift, and artificial lift systems in onshore and offshore wells and to continue producing for conventional and unconventional wells. Examples of electrical feedthrough assembly, according to embodiments herein, may include a two-piece assembly for nominal wellhead sizes range from <NUM>,<NUM> (<NUM><NUM>/<NUM> inches) to <NUM>,<NUM> (<NUM> inches) and above, and with any power range required for various well operations. Achieving a successful conductor connection of the electrical feedthrough assembly in the tubing hanger is an important part of a well operation. Additional challenges further exist in a subsea environment for safely conductively connecting the electrical feedthrough assembly to the tubing hanger while both minimizing costs and providing reliability for future changes to the overall layout of a field or well.

Accordingly, one or more embodiments in the present disclosure may be used to overcome such challenges as well as provide additional advantages over conventional methods of retention, as will be apparent to one of ordinary skill. In one or more embodiments, an electrical feedthrough assembly may be safer, faster, and lower in cost as compared with conventional methods due, in part, to multiple electrical contacts within the electrical feedthrough assembly conductively connecting conductors from a lower and upper assembly of the electrical feedthrough assembly. Additionally, the electrical feedthrough assembly may comprise a chamber (with grease) and pin end within the upper assembly to aid in conductively connecting the conductor from the lower assembly to the conductor of the upper assembly to form a continuous conductor that require no need for bladders with various fluid profiles, and thus, relaxing control tolerances and improving manufacture (i.e. reduced cost and reduced time to manufacture). Overall the electrical feedthrough assembly may minimize product engineering, risk associated with electrical feedthrough assembly, reduction of assembly time, hardware cost reduction, and weight and envelope reduction. It is further envisioned that the electrical feedthrough assembly may be used periodically for various well operations for limited period of times. In some instances, the electrical feedthrough assembly may be periodically re-greased in the chamber of the upper assembly. Additionally, one skilled in the art will appreciate how the electrical feedthrough assembly, according to embodiments herein, may be attached to any subsea devices without the departing from the scope of the present disclosure.

Furthermore, methods of the present disclosure may include use of the electrical feedthrough assembly <NUM> and other structures, such as in <FIG> for providing power to subsea devices. Because the method may apply to any of the embodiments, reference numbers are not referenced to avoid confusion of the numbering between the different embodiments.

Initially, a lower assembly of an electrical feedthrough assembly is coupled to a tubing hanger. In a non-limiting example, a first FMJ connector inserted into an opening of a lower housing of the lower assembly is connected to a tubing hanger connector such that a conductor of the lower assembly extends into the tubing hanger. Additionally, an electrical penetrator may be used to aid in continuing the conductor into the lower assembly. Next, an upper assembly of the electrical feedthrough assembly is landed on the lower assembly. In a non-limiting example, a pin end at a first end of the upper assembly is inserted into an opening of an upper housing of the lower assembly opposite the end of the FMJ connector. Further, first end of the upper assembly lands within the lower assembly. By inserting the pin end, a conductor connector of the conductor of the lower assembly extends into the upper assembly though the pin end to contact a first electrical contact in the upper assembly. Further, the first electrical contact is connected to a second electrical contact via a wire and a conductor of the upper assembly contacts the second electrical contact. With the conductor of the lower assembly contacting the first electrical contact, the conductor of the lower assembly is conductively connected to the conductor of the upper assembly forming a continuous conductor line. In addition, a second FMJ connector inserted into an opening at the second end of lower assembly is connected to a subsea tree.

In some embodiments, a chamber is provided within the upper assembly. When the pin end of the upper assembly is inserted into the lower assembly, the conductor of the lower assembly enters the chamber. In addition, seals are provided in the chamber to seal around the conductor of the lower assembly. Further, the conductor of the lower assembly comes into contact with the first electrical contact within the chamber. Furthermore, the first electrical contact extends out of the chamber such that the wire may connect the first electrical contact to the second electrical contact outside of the chamber. It is further envisioned that the chamber may be provided with grease to electrically lubricate the conductor of the lower assembly and the first electrical contact. Additionally, the chamber may be periodically re-greased for various well operations. In some embodiments, fluids from a surrounding enjoinment may flow into and out of the upper assembly via a port in fluid communication with the chamber. Furthermore, the fluids may be contained or released within the chambers by selectively opening or closing a valve of the port. At a second end of the upper assembly, the conductor of the upper assembly extends outwardly to connect to a power/electrical such that power/electricity may be provided to the electrical feedthrough assembly. Furthermore, lengths of the conductors in the lower and upper assemblies may be insulated with PEEK molding. Additionally, glass bodies may be provided on the conductors in the lower and upper assemblies. It is further envisioned that glass-to-metal seals may be provided to seal the glass bodies from metal parts. In addition, metal-to-metal seal may be provided to seal any meat parts within the electrical feedthrough assembly. With the electrical feedthrough assembly attached from the tubing hanger to subsea tree, power/electricity may travel from a source (at the seabed, platform, or onshore), via cables or wires, to the conductors of the electrical feedthrough assembly such that power/electricity may be provided to subsea devices.

Claim 1:
An electrical feedthrough assembly (<NUM>), comprising:
a lower assembly (<NUM>) having a first end (<NUM>) and a second end (<NUM>), wherein the lower assembly (<NUM>) comprises:
an outer body (<NUM>) with a lower housing (<NUM>) and an upper housing (<NUM>) disposed within a bore (<NUM>) of the outer body (<NUM>),
wherein the lower housing (<NUM>) extends axial outward from the outer body (<NUM>) to form the first end (<NUM>),
wherein the upper housing (<NUM>) extends axial outward from the outer body (<NUM>) to form the second end (<NUM>), and
a first conductor (<NUM>) extending from the lower housing (<NUM>) to the upper housing (<NUM>), wherein at least one portion of the first conductor (<NUM>) is enclosed in a first insulator (<NUM>); and
an upper assembly (<NUM>) having a body (<NUM>, <NUM>) extending from a first end (<NUM>) to a second end (<NUM>) of the upper assembly (<NUM>), wherein the upper assembly (<NUM>) comprises:
a pin end (<NUM>) at the first end (<NUM>), wherein the pin end (<NUM>) is inserted into an opening (<NUM>) of the second end (<NUM>) of the lower assembly (<NUM>),
a second conductor (<NUM>) disposed within the body (<NUM>, <NUM>), wherein at least one portion of the second conductor (<NUM>) is enclosed in a second insulator (<NUM>) and wherein the second conductor (<NUM>) extends out from the upper assembly (<NUM>), and
a chamber (<NUM>) within the body (<NUM>, <NUM>) having an opening (<NUM>) at the first end (<NUM>) of the upper assembly (<NUM>) for receiving the first conductor (<NUM>), wherein the chamber (<NUM>) includes grease (<NUM>) and is configured to hold the first conductor (<NUM>),
wherein the second conductor (<NUM>) is conductively connected to the first conductor (<NUM>),
wherein a length of the first conductor (<NUM>) is in contact with a first electrical contact (136a) of the upper assembly (<NUM>),
wherein the first electrical contact (136a) is connected to a second electrical contact (136b) via a conductive wire (<NUM>), and
wherein the second electrical contact (136b) is conductively connected to the second conductor (<NUM>).