Embodiments disclosed herein relate generally to subsea oil and gas operations equipment. More specifically, embodiments disclosed herein relate to systems and methods of use for an electrical feedthrough to provide power to subsea equipment.
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 10 bar (about 145 PSI) for every 100 m depth in the ocean, and thus, for electrical systems needing to be located at a water depth of about 3000 m, the electrical systems encounters about 300 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 3,000 m, 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 20 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.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
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.
In one aspect, the embodiments disclosed herein relate to a method of connecting a first end of a lower assembly of an electrical feedthrough assembly to a subsea device; inserting a pin end at a first end of an upper assembly of the electrical feedthrough assembly into a second end of the lower assembly; passing a first conductor of the lower assembly through the pin end and into the upper assembly; inserting the first conductor into a chamber of the upper assembly; contacting the first conductor to a first electrical contact in the upper assembly, wherein a second conductor of the upper assembly is in contact with a second electrical contact connected to the first electrical contact via a conductive wire; connecting a second end of a upper assembly to a subsea tree; contacting the third conductor of a power source to a third electrical contact in the upper assembly; and powering subsea devices conductively through the electrical feedthrough assembly.
Other aspects and advantages will be apparent from the following description and 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. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description. 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.
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In one or more embodiments, the upper assembly 102 is lowered (see arrow 143) into the lower assembly 101 such that a portion of the upper assembly 102 is within the lower assembly 101. In a non-limiting example, the pin end 134 of the upper assembly 102 is inserted into the opening 131 of the lower assembly 101 such that a conductor 128 of the lower assembly 101 is conductively connected to the conductor 135 of the upper assembly 102. It is further envisioned that the upper assembly 102 may include a plurality of electrical contacts (136a, 136b). While it is noted that
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 20 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 7 1/16 inches to 11 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 100 and other structures, such as in
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.
While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the disclosure as described herein. Accordingly, the scope of the disclosure should be limited only by the attached claims.
Filing Document | Filing Date | Country | Kind |
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PCT/US2020/018851 | 2/19/2020 | WO | 00 |
Number | Date | Country | |
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62808122 | Feb 2019 | US |