Deployment tubing connector having internal electrical penetrator

Information

  • Patent Grant
  • 6332499
  • Patent Number
    6,332,499
  • Date Filed
    Tuesday, November 23, 1999
    25 years ago
  • Date Issued
    Tuesday, December 25, 2001
    23 years ago
Abstract
A connector for use in a deployment system able to deploy and power a device, such as an electric submergible pumping system, in a well. The connector includes pluggable ends that permit connection adjacent segments, each having an outer section of tubing and an internal power cable. Each connector includes a tubing connector portion and a power cable connector portion that permit pluggable connection of sequential tubing segments when deploying a device or system downhole.
Description




FIELD OF THE INVENTION




The present invention relates generally to a system for deploying well-related equipment, such as electric submergible pumping systems, and particularly to a connector that permits secure connection of segments of combined external deployment tubing and internal power cable.




BACKGROUND OF THE INVENTION




A variety of systems are used for deploying equipment used in the production of fluids, such as oil, from producing wells. For example, tubing has commonly been used for the deployment of downhole equipment. Electric submergible pumping systems, for instance, may be deployed by appropriate deployment tubing to a desired location within a wellbore. Depending on the application, the production fluid is produced either through the center of the tubing or through the annulus formed between the tubing and the wellbore casing.




When deploying systems, such as electric submergible pumping systems, it is necessary to provide power to the system. Accordingly, a power cable is connected between a power supply at the surface and a submergible electric motor of the electric submergible pumping system. The power cable generally is either tied to the outside of the tubing or routed through the center of the tubing. For example, if the production fluid is produced through the annulus formed around the deployment tubing, it is convenient to provide power cable through the center of the tubing.




One type of commonly used tubing is coiled tubing. Coiled tubing may be transported in rolls that are unrolled during deployment of the downhole system for relatively rapid and convenient deployment of the system, e.g. an electric submergible pumping system. For certain applications, a power cable is disposed in the center of the coiled tubing. by way of example, Reda of Bartlesville, Okla., a division of Schlumberger Corporation, manufactures REDACoil™, a product in which power cable is prepackaged within coiled tubing. Repairing or connecting lengths of coiled tubing with internal power cable can be difficult, particularly when the splice is made in the field.




Also, the coiled tubing and internal power cable generally are formed in the lengths necessary to accommodate deployment of the electric submergible pumping system to a desired location within a wellbore. However, extremely long lengths of tubing and power cable can be difficult to handle, and the equipment used to deploy downhole systems may be limited to a given length of tubing.




In certain applications, e.g. deep wells, and in certain situations in which the deployment tubing requires repair, it would be advantageous to have a connector system that permitted a relatively simple combination of independent segments of tubing, particularly coiled tubing having a combined power cable.




SUMMARY OF THE INVENTION




The present invention features a connector system for connecting sections of tubing used in deploying a downhole device for production of fluid from a well. The connector system includes a tubing connector having an upper nipple section sized for receipt in a first tubing end. The tubing connector also includes a lower nipple section sized for receipt in a second tubing end. The tubing connector also includes a hollow interior for receiving an electrical feed-through. The electrical feed-through has a first connection end, a second connection end and a plurality of conductors extending between the first and the second connection ends. The tubing connector and the electrical feed-through provide for ready connection of segments in a modular deployment system.




According to another aspect of the invention, a coiled tubing connection system is provided. The system includes a first segment of coiled tubing having a first connector end and a first hollow interior. The system also includes a first power cable disposed in the hollow interior and having a first plug proximate the first connector end. A second segment of coiled tubing has a second connector end and a second hollow interior. Also, a second power cable is disposed in the second hollow interior and has a plug proximate the second connector end. The system further includes a coiled tubing connector having a housing sized to selectively engage the first connector end and the second connector end. The coiled tubing connector further includes an internal plug assembly positioned to conductively engage the first plug and the second plug when the first and second connector ends are engaged with the coiled tubing connector.




According to another aspect of the invention, a connector is provided for use in wellbore environments to connect segments of a tubing-style deployment system. The connector includes an outer housing having a pair of connection ends positioned to connect two consecutive sections of tubing in a wellbore. Additionally, the connector includes an internal electrical connector assembly disposed within the outer housing to electrically couple a power cable deployed within the two consecutive sections of tubing.











BRIEF DESCRIPTION OF THE DRAWINGS




The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and





FIG. 1

is a front elevational view of an exemplary deployment system, deploying an electric submergible pumping system, according to a preferred embodiment of the present invention;





FIG. 2

is cross-sectional view taken generally along the axis of a portion of the connector system utilized in connecting sequential segments of deployment tubing having internal power cable;





FIG. 3

is a cross-sectional view similar to that of

FIG. 2

but showing an internal electrical feed-through, according to one embodiment of the present invention;





FIG. 4

is a partial cross-sectional view showing the connector system components of

FIG. 3

connecting sequential segments of coiled tubing;





FIG. 5

is a partial cross-sectional view of the electrical feed-through showing an exemplary plug portion;





FIG. 6

is a top view of the plug portion illustrated in

FIG. 5

;





FIG. 7

is a partial cross-sectional view of the end of a tubing segment showing the plug portion designed for selective engagement with the plug portion illustrated in

FIGS. 5 and 6

; and





FIG. 8

is a bottom view of the tubing segment plug illustrated in FIG.


7


.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring generally to

FIG. 1

, an exemplary deployment system


10


is illustrated in a wellbore environment. Deployment system


10


is attached to an electric submergible pumping system


12


and preferably a bottom intake system. Deployment system


10


can be utilized in the deployment of a wide variety of devices or systems, but the unique design of deployment system


10


is particularly amenable to deployment of electric submergible pumping systems


12


.




A typical bottom intake pumping system


12


may comprise a variety of components depending on the particular application or environment in which it is used. Typically, system


12


includes at least a submergible pump


14


, a pump intake


15


, a submergible motor


16


, a motor protector


17


and a packer assembly


18


. However, a variety of other or additional components can be utilized in the system.




For example, system


12


may include a thrust section


19


and a connector


20


by which submergible pumping system


12


is coupled to deployment system


10


. Also, a variety of component types may be utilized. For instance, an exemplary motor


16


is a three-phase, induction-type motor, and an exemplary pump


14


is a multi-stage centrifugal pump. In this type of system, submergible pump


14


draws wellbore fluid through pump intake


15


and discharges it through a packer discharge head


21


above the packer assembly


18


into the annulus formed about deployment system


10


. A variety of packer assemblies also may be utilized, such as a mechanically set packer or a hydraulic packer, such as the Camco HRP-1-SP Hydraulic Set Packer available through Camco of Houston, Tex.




In the example illustrated, system


12


is designed for deployment in a well


22


within a geological formation


24


that contains desirable production fluids, such as petroleum. In a typical application, a wellbore


26


is drilled and lined with a wellbore casing


28


. Wellbore casing


28


may include a plurality of openings


30


, often called perforations, through which production fluids flow into wellbore


26


.




Although deployment system


10


may have a variety of forms and configurations, it typically comprises tubing, and preferably two or more sections of coiled tubing


32


. A power cable


34


is disposed within a hollow interior


36


of the tubing


32


. The power cable


34


is supported within tubing


32


by appropriate anchors, buoyancy fluid or other means. Power cable


34


often includes at least three conductors


33


surrounded by one or more layers of insulation


35


and an outer protective armor


37


.




As illustrated, deployment system


10


comprises two or more segments


38


connected by one or more connector systems


40


. Each segment


38


includes an outer tube, e.g. a section of coiled tubing


32


, and a combined power cable, such as an internal power cable


34


.




Referring generally to

FIG. 2

, a portion of one of the connector systems


40


is illustrated.

FIG. 2

shows a tubing connector


42


that permits the secure connection of the tubing


32


of one segment


38


to the tubing of the next sequential tubing segment


38


. Tubing connector


42


includes a pair of nipples or inserts, referred to as an upper insert


44


and a lower insert


46


, sized for insertion into the hollow tubing interiors of adjacent segments


38


. Tubing connector


42


also includes an expanded region


48


disposed between upper insert


44


and lower insert


46


. Expanded region


48


provides an upper abutment surface


50


and a lower abutment surface


52


. Upper and lower abutment surfaces


50


,


52


provide a stop against which the external tubing


32


of adjacent segments


38


abut when slid over cylindrical upper insert


44


and cylindrical lower insert


46


.




Preferably, each tubing connector


42


includes one or more seals disposed to prevent liquid flow between tubing connector


42


and an attached deployment system segment


38


. In the illustrated embodiment, upper insert


44


includes a pair of annular grooves


54


formed in an external surface


56


. A sealing member


58


, such as an elastomeric seal, is disposed in each groove


54


to encircle upper insert


44


and to provide a liquid-tight seal between upper insert


44


and a connected segment


38


.




Similarly, lower insert


46


includes a pair of annular grooves


60


formed in an exterior surface


62


. A sealing member


64


, such as an elastomeric seal, is disposed in each annular groove. Seal members


64


provide a liquid-tight seal between lower insert


46


and a connected segment


38


. It should be noted that the actual number of seal members


58


,


64


may be one or more depending on such factors as tubing connector design and application of the overall deployment system.




Additionally, a retention system


66


is used to ensure that segments


38


remain connected to tubing connector


42


during deployment and use of downhole system


12


. In the illustrated embodiment, retention system


66


includes a plurality of dimples


68


formed in exterior surface


56


of upper insert


44


and exterior surface


62


of lower insert


46


. Dimples


68


permit the slight deformation of the coiled tubing


32


of each segment


38


once attached to tubing connector


42


. The sidewall of each section of tubing


32


is appropriately deformed in a radially inward direction such that it deforms into dimples


68


(see

FIG. 4

) to prevent the attached segment


38


from inadvertently sliding off the upper insert


44


or lower insert


56


to which it is attached.




Tubing connector


42


also includes a hollow interior


70


that preferably extends generally along a longitudinal axis


72


. Hollow interior


70


is defined by an interior wall surface


74


that extends between an upper opening


76


and a lower opening


78


.




Hollow interior


70


is sized to receive an electrical feed-through


80


, as illustrated in FIG.


3


. Feed-through


80


is designed for connection to the internal power cable


34


included in each segment


38


. Thus, each connector system


40


includes a tubing connector


42


and an electrical feed-through


80


to couple sequential segments


38


both mechanically and electrically.




In the illustrated embodiment, feed-through


80


includes an outer housing


82


that may be formed from a suitable metal or plastic. Outer housing


82


includes a midsection


84


, an upper plug portion


86


and a lower plug portion


88


. In the exemplary embodiment, midsection


84


has a larger diameter than upper plug portion


86


or lower plug portion


88


. The diameter of midsection


84


may be slightly less than the diameter of interior surface


74


to permit feed-through


80


to be slid into the center of hollow interior


70


. Additionally, one or more annular seals, such as O rings, may be disposed about midsection


84


to form a seal between feed-through


80


and interior surface


74


of tubing connector


42


.




Preferably, upper plug portion


86


and lower plug portion


88


are generally cylindrical in shape and have a smaller diameter than midsection


84


. In the illustrated design, the smaller diameter of the plug portions facilitates the selective, pluggable connection with sections of power cable disposed within adjacent segments


38


. Specifically, the smaller diameter of upper plug portion


86


provides for the formation of an annular space


92


between upper plug portion


86


and interior surface


74


. Similarly, the size and shape of lower plug portion


88


provides for the formation of an annular space


94


between plug portion


88


and interior surface


74


. Additionally, each plug portion


86


,


88


may include regions that facilitate the secure connection between feed-through


80


and adjacent power cable sections. For example, each plug portion may include one or more regions of ridges


96


or other surface abnormalities to help maintain secure mechanical and electrical connection.




Referring generally to

FIG. 4

, an entire exemplary connector system


40


is illustrated. Each segment


38


includes an outer section of tubing


32


, preferably coiled tubing, and an internal power cable section


34


. Each modular segment includes a segment connector end


100


designed for both mechanical and electrical connection into connector system


40


.




As illustrated, the coiled tubing


32


of each connector end


100


has an interior surface


102


of appropriate size to permit sliding engagement with either upper insert


44


or lower insert


46


. Preferably, a retention system is used to maintain secure connection between tubing segment


38


and either upper insert


44


or lower insert


46


. In the exemplary embodiment, a plurality of tubing dimples


104


are formed in the tubing sidewall of each tubing segment


38


such that the tubing material, typically steel, is deformed into dimples


68


of tubing connector


42


.




Additionally, each section connector end


100


includes an electrical connector, such as a plug


106


, that is electrically connected with the corresponding power cable section


34


. In the exemplary embodiment, each plug


106


is sized for insertion into hollow interior


70


to achieve mating engagement with the corresponding plug portion


86


or


88


. Preferably, the length of plug


106


is selected to permit an end of tubing


32


for each segment


38


to lie proximate or against the corresponding abutment surface


50


or


52


when the plug


106


is engaged with its corresponding plug portion of feed-through


80


.




Although a variety of plug styles may be selected, the illustrated plug is sized and designed such that it can slide into hollow interior


70


and along annular space


92


or


94


as it engages upper plug portion


86


or lower plug portion


88


, respectively. Generally, each plug


106


is disposed adjacent midsection


84


when fully engaged.




It is preferred that each plug


106


be mounted securely in its corresponding section connector end


100


. Accordingly, each plug


106


may be connected to tubing


32


by a connection block


108


. Connection block


108


may have a variety of forms, including epoxy blocks or metallic blocks that are mounted in place via appropriate notches and grooves, ring clips disposed above and beneath the connection block, set screws extending through tubing


32


, etc. In some applications, it also may be desirable to seal connection block


108


against interior surface


102


of tubing


32


by appropriate O rings or other seals (not shown). By forming an appropriate seal between each connection block


108


and tubing


32


, the interior of each tubing section


32


, intermediate connection blocks


108


, can be filled with a buoyancy fluid


110


having a specific gravity selected to support power cable


34


within tubing


32


. However, a variety of mechanical power cable anchors and supports can be utilized to support the power cable, as with conventional systems.




A variety of connectors, including other types of plug connectors, can be used for forming the connection between power cable


44


and electrical feed-through


80


to ensure, for example, power delivery to submergible motor


18


. In a typical power delivery system, the connectors, e.g. plugs, must be designed to facilitate the transfer of three-phase power, typically through three or more conductors. An exemplary plug connector system is illustrated in

FIGS. 5 through 8

.




Referring first to

FIGS. 5 and 6

, an exemplary upper plug portion


86


is illustrated. It should be noted that the description of upper plug portion


86


also applies to lower plug portion


88


. As illustrated, upper plug portion


86


is a female plug having an exterior defined by outer housing


82


. Within outer housing


82


, plug portion


86


includes an inner support material


112


, such as an insulative plastic plug material. The support material


112


may be connected to housing


82


by appropriate tabs


114


designed to engage corresponding features formed in housing


82


. Additionally, support material


112


is designed to support a plurality, e.g. three, conductive receptacles


116


.




Each conductive receptacle


116


preferably includes a tapered inlet region


118


to facilitate the insertion of corresponding conductive prongs, as will be described below. Each tapered inlet


118


is formed from a conductive material that is typically a conductive metallic material. Furthermore, each tapered inlet


118


is connected to a conductor


120


that passes longitudinally through feed-through


80


to corresponding conductive receptacles in lower plug portion


88


.




Referring now to

FIGS. 7 and 8

, an exemplary plug


106


is illustrated as designed for mating engagement with a corresponding plug portion


86


or


88


of electric feed-through


80


. As illustrated, each plug is defined by a plug housing


122


having an annular end portion


124


defining a hollow end region


126


. A plurality of prongs


128


extend into hollow end region


126


to form a male plug portion designed for mating engagement with, for example, upper plug portion


86


.




In the specific example illustrated, there are three prongs


128


properly arranged to slide into corresponding conductive receptacles


116


when the tubing segment


38


is inserted into engagement with upper insert


44


or lower insert


46


. Prongs


128


typically are metallic prongs electrically connected to corresponding conductors


130


that extend through plug


106


and power cable


34


.




During coupling of adjacent modular segments


38


, prongs


128


are slid into receptacles


116


as annular end portion


124


slides into either annular space


92


or


94


. Simultaneously, insert


44


or


46


slides into an annulus


132


formed between plug


106


and tubing


32


at section connector end


100


. Thus, a plurality of modular segments can be connected and/or disconnected relatively simply and easily by inserting (or removing) the connector inserts


44


,


46


into adjacent section connector ends


100


of sequential modular segments.




The use of a connector system


40


permits ready repair of coiled tubing, combination of multiple lengths of tubing, and the manufacture of standardized lengths of coiled tubing segments that may be mounted on a wider variety of deployment equipment. The modular coiled tubing segments simply can be plugged together to deploy a given system, such as electric submergible pumping system


12


, to a desired depth within the wellbore.




It will be understood that the foregoing description is of preferred exemplary embodiments of this invention, and that the invention is not limited to the specific forms shown. For example, a variety of electrical connectors can be utilized; various retention systems may be used to maintain a solid connection between modular tubing sections and connectors during deployment; the male and female plugs can be reversed; a variety of materials may be used in forming the electrical feed-through and the tubing connector; and the components may be made in a variety of sizes and diameters. Additionally, locational language, such as “upper” and “lower”, is used in the description above is only to facilitate explanation of the illustrated embodiment, and it should not be construed as limiting the scope of the invention. These and other modifications may be made in the design and arrangement of the elements without departing from the scope of the invention as expressed in the appended claims.



Claims
  • 1. A connector system for connecting sections of tubing used in deploying a device for production of a fluid, comprising:a tubing connector having an upper nipple section sized for receipt in a first tubing end and a lower nipple section sized for receipt in a second tubing end, the tubing connector having a hollow interior; and an electrical feed-through disposed in the hollow interior, the electrical feed-through having a first connection end, a second connection end, and a plurality of conductors extending between the first and the second connection ends.
  • 2. The connector system as recited in claim 1, wherein the tubing connector includes an expanded midsection having a first abutment surface against which the first tubing end may abut and a second abutment surface against which the second tubing end may abut.
  • 3. The connector system as recited in claim 2, further comprising a plurality of external seals disposed about the tubing connector.
  • 4. The connector system as recited in claim 1, wherein the first connection end comprises a first plug portion having a plurality of receptacles, each receptacle being coupled to a corresponding conductor of the plurality of conductors.
  • 5. The connector system as recited in claim 3, further comprising a plurality of internal seals disposed between the tubing connector and the electrical feed-through.
  • 6. The connector system as recited in claim 4, wherein the second connection end comprises a second plug portion having a plurality of receptacles, each receptacle being coupled to a corresponding conductor of the plurality of conductors.
  • 7. The connector system as recited in claim 1, wherein the upper nipple section includes a plurality of external dimples to permit interlocking engagement with the first tubing end.
  • 8. The connector system as recited in claim 1, wherein the lower nipple section includes a plurality of external dimples to permit interlocking engagement with the second tubing end.
  • 9. The connector system as recited in claim 7, wherein the lower nipple section includes a plurality of external dimples to permit interlocking engagement with the second tubing end.
  • 10. The connector system as recited in claim 1, wherein the plurality of conductors include three conductors to permit the use of three-phase power.
  • 11. A coiled tubing connection system, comprising:a first segment of coiled tubing having a first connector end and a first hollow interior; a first power cable disposed in the first hollow interior and having a first plug proximate the first connector end; a second segment of coiled tubing having a second connector end and a second hollow interior; a second power cable disposed in the second hollow interior and having a second plug proximate the second connector end; and a coiled tubing connector having a housing sized to selectively engage the first connector end and the second connector end, the coiled tubing connector further including an internal plug assembly positioned to conductively engage the first plug and the second plug when the first and second connector ends are engaged with the coiled tubing connector.
  • 12. The coiled tubing connection system as recited in claim 11, wherein the housing includes a pair of nipple sections sized for insertion into the first connector end and the second connector end.
  • 13. The coiled tubing connection system as recited in claim 12, wherein the housing includes an expanded midsection disposed intermediate the first connector end and the second connector end.
  • 14. The coiled tubing connection system as recited in claim 13, wherein the coiled tubing connector includes at least one seal disposed about each nipple section.
  • 15. The coiled tubing connection system as recited in claim 14, wherein the coiled tubing connector includes an internal seal disposed between the housing and the internal plug assembly.
  • 16. The coiled tubing connection system as recited in claim 11, wherein the internal plug assembly includes opposed female plug ends having receptacles arranged to receive the first plug and the second plug.
  • 17. The coiled tubing connection system as recited in claim 11, wherein the internal plug assembly includes opposed plug ends in which at least one of the opposed plug ends comprises a female plug end.
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