# Patent

## Title
Spoolable composite coiled tubing connector

## Abstract

A connector providing methods and apparatus for connecting two lengths of composite coiled tubing whereby the connector can be spooled with the tubing onto a reel. Embodiments of the connector include female and male housings which join together to create the coiled tubing connection providing mechanical and electrical or fiber optic connectivity between the two lengths of tubing. A connecting member on the male housing connectably engages the female housing. Splines on the male housing also align with corresponding flutes on the female housing. The female and male housings each attach to end portions of coiled tubing through a clamped connection and with the housings and connecting member being substantially flush with the outside diameter of the coiled tubing.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part application of U.S. application Ser. No. 09/534,685, filed Mar. 24, 2000 now U.S. Pat. No. 6,761,574 and entitled Coiled Tubing Connector, which is a divisional and continuation-in-part of U.S. patent application Ser. No. 09/081,961 filed May 20, 1998 now U.S. Pat. No. 6,296,066 and entitled Drilling System, which claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Application Ser. No. 60/063,326, filed Oct. 27, 1997 and entitled Drilling System, all of these applications being hereby incorporated herein by reference.


STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
FIELD OF THE INVENTION
The present invention relates generally to devices used to connect lengths of coiled tubing and more particularly to devices used to connect lengths of composite coiled tubing. Another feature of the present invention relates to providing a mechanical connection of sufficient strength so that forces of tension, compression, and torque can be transferred from one length of tubing to the other through the connector. Further the connection between lengths of tubing is hydraulically sealed so as to separate fluids conducted inside the tubing and the connector from any fluids on the outside of the tubing and connector. The connector also permits the fluids inside a length of tubing to flow through the connector on to the sequential length of tubing. The connector of the present invention also provides a mechanism that permits the lengths of tubing to be connected without imparting any rotation on either length of tubing. Additionally, the invention relates to connectors that will also allow an electrical connection from the joining of electrical wires, or other types of signaling cables, embedded within each multi-conductor pair of tubing to be joined. The electrical connection provides seals and insulation that insulates both wire-to-wire and wire-to-fluid.
BACKGROUND OF THE INVENTION
Many existing wells include hydrocarbon pay zones which were bypassed during drilling and completion because such bypassed zones were not economical to complete and produce. Offshore drilling rigs cost approximately $40 million to build and may cost as much as $250,000 a day to lease. Such costs preclude the use of such expensive rigs to drill and complete these bypassed hydrocarbon pay zones. Presently, there is no cost effective methods of producing many bypassed zones. Thus, often only the larger oil and gas producing zones are completed and produced because those wells are sufficiently productive to justify the cost of drilling and completion using offshore rigs.
Many major oil and gas fields are now paying out and there is a need for a cost effective method of producing these previously bypassed hydrocarbon pay zones. The locations and size of these bypassed hydrocarbon zones are generally known, particularly in the more mature producing fields.
To economically drill and complete the bypassed pay zones in existing wells, it is necessary to eliminate the use of conventional rigs and conventional drilling equipment. One method of producing wells without rigs is the use of metal coiled tubing with a bottom hole assembly. See for example U.S. Pat. Nos. 5,215,151; 5,394,951 and 5,713,422, all incorporated herein by reference. The bottom hole assembly typically includes a downhole motor providing the power to rotate a bit for drilling the borehole. The bottom hole assembly operates only in the sliding mode since the metal coiled tubing is not rotated at the surface like that of steel drill pipe which is rotated by a rotary table on the rig. The bottom hole assembly may or may not include a tractor which propels the bottom hole assembly down the borehole. One such tractor is a thruster that pushes off the lower terminal end of the coiled tubing and does not rely upon contacting or gripping the inside wall of the borehole. The depth that can be drilled by such a bottom hole assembly is limited.
Coiled tubing, as currently deployed in the oilfield industry, generally includes small diameter cylindrical tubing having a relatively thin wall made of metal or composite material. Coiled tubing is typically much more flexible and of lighter weight than conventional drill pipe. These characteristics of coiled tubing have led to its use in various well operations. For example, coiled tubing is routinely utilized to inject gas or other fluids into the well bore, inflate or activate bridges and packers, transport well logging tools downhole, perform remedial cementing and clean-out operations in the well bore, and to deliver or retrieve drilling tools downhole. The flexible, lightweight nature of coiled tubing makes it particularly useful in deviated well bores.
Typically, coiled tubing is introduced into the oil or gas well bore through wellhead control equipment. A conventional handling system for coiled tubing can include a reel assembly, a gooseneck, and a tubing injector head. The reel assembly includes a rotating reel for storing coiled tubing, a cradle for supporting the reel, a drive motor, and a rotary coupling. During operation, the tubing injector head draws coiled tubing stored on the reel and injects the coiled tubing into a wellhead. The drive motor rotates the reel to pay out the coiled tubing and the gooseneck directs the coil tubing into the injector head. A rotary coupling provides an interface between the reel assembly and a fluid line from a pump. Fluids are often pumped through the coiled tubing during operations. Such arrangements and equipment for coiled tubing are well known in the art.
The use of metal coiled tubing has various deficiencies. Metal coiled tubing tends to buckle the deeper the bottom hole assembly penetrates the borehole. Buckling is particularly acute in deviated wells where gravity does not assist in pulling the tubing downhole. As the tubing buckles, the torque and drag created by the contact with the borehole becomes more difficult to overcome and often makes it impractical or impossible to use coiled tubing to reach distant bypassed hydrocarbon zones. Further, steel coiled tubing often fatigues from cyclic bending early in the drilling process and must be replaced. It has also been found that coiled tubing may be as expensive to use as a conventional drilling system using jointed steel pipe and a rig.
While prior art coiled tubing handling systems are satisfactory for coiled tubing made of metal such as steel, these systems do not accommodate the relatively long spans or drill string lengths achievable with coiled tubing made of composites. Such extended spans of composite coiled tubing strings are possible because composite coiled tubing is significantly lighter than steel coiled tubing. In fact, composite coiled tubing can be manufactured to have neutral buoyancy in drilling mud. With composite coiled tubing effectively floating in the drilling mud, downhole tools, such as tractors, need only overcome frictional forces in order to tow the composite coiled tubing through a well bore. This characteristic of composites markedly increases the operational reach of composite coiled tubing. Thus, composite coiled tubing may well allow well completions to depths of 20,000 feet or more, depths previously not easily achieved by other methods.
Moreover, composite coiled tubing is highly resistant to fatigue failure caused by “bending events,” a mode of failure that is often a concern with steel coiled tubing. At least three bending events may occur before newly manufactured coiled tubing enters a well bore: unbending when the coiled tubing is first unspooled from the reel, bending when travelling over a gooseneck, and unbending upon entry into an injector. Such accumulation of bending events can seriously undermine the integrity of steel coiled tubing and pose a threat to personnel and rig operations. Accordingly, steel coiled tubing is usually retired from service after only a few trips into a well bore. However, composite coiled tubing is largely unaffected by such bending events and can remain in service for a much longer period of time.
Hence, systems utilizing composite coiled tubing can be safely and cost-effectively used to drill and explore deeper and longer wells than previously possible with conventional drilling systems. Moreover, completed but unproductive wells may be reworked to improve hydrocarbon recovery. Thus, composite coiled tubing systems can allow drilling operations into formations that have been inaccessible in the past and thereby further maximize recovery of fossil fuels.
However, these dramatic improvements in drilling operations cannot be realized without handling systems that can efficiently and cost-effectively deploy extended lengths of composite coiled tubing. Prior art coiled tubing handling systems do not readily accommodate the reel change-outs needed when injecting thousands of feet of coiled tubing downhole. Prior art coiled tubing handling systems require a work stoppage to change out an empty reel for a full reel. Because such a procedure is inefficient, there is a need for a coiled tubing handling system that more efficiently changes out successive reels of coiled tubing.
Composite coiled tubing offers the potential to exceed the performance limitations of isotropic metals, thereby increasing the service life of the pipe and extending operational parameters. Composite coiled tubing is constructed as a continuous tube fabricated generally from non-metallic materials to provide high body strength and wear resistance. This tubing can be tailored to exhibit unique characteristics which optimally address burst and collapse pressures, pull and compression loads, as well as high strains imposed by bending. This enabling capability expands the performance parameters beyond the physical limitations of steel or alternative isotropic material tubulars. In addition, the fibers and resins used in composite coiled tubing construction make the tube impervious to corrosion and resistant to chemicals used in treatment of oil and gas wells.
High performance composite structures are generally constructed as a buildup of laminated layers with the fibers in each layer oriented in a particular direction or directions. These fibers are normally locked into a preferred orientation by a surrounding matrix material. The matrix material, normally much weaker than the fibers, serves the role of transferring load into the fibers. Fibers having a high potential for application in constructing composite pipe include glass, carbon, and aramid. Epoxy or thermoplastic resins are good candidates for the matrix material.
A composite umbilical or coiled tubing typically has an impermeable fluid liner, a plurality of load carrying layers, and a wear layer. A plurality of conductors may be embedded in the load carrying layers. These conductors may be metallic or fiber optic conductors such as electrical conductors and data transmission conductors. One or more of the data transmission conduits may include a plurality of sensors. It should be appreciated that the conductors may be passages extending the length of an umbilical for the transmission of pressure fluids.
Types of composite tubing are shown and described in U.S. Pat. Nos. 5,018,583; 5,097,870; 5,176,180; 5,285,008; 5,285,204; 5,330,807; 5,348,096; and 5,469,916, each of these patents is incorporated herein by reference. See also “Development of Composite Coiled Tubing for Oilfield Services,” by A. Sas-Jaworsky and J. G. Williams, SPE Paper 26536, 1993, incorporated herein by reference. U.S. Pat. Nos. 5,080,175; 5,172,765; 5,234,058; 5,437,899; and 5,540,870, each of these patents being incorporated herein by reference, disclose composite rods, electrical or optical conductors housed in a composite cable.
The impermeable fluid liner is often an inner tube preferably made of a polymer, such as polyvinyl chloride or polyethylene. The liner can also be made of a nylon, other special polymer, or elastomer. In selecting an appropriate material for a fluid liner, consideration is given to the chemicals in the drilling fluids to be used in drilling the sidetracked well and the temperatures to be encountered downhole. The primary purpose for an inner liner is as an impermeable fluid barrier since carbon fibers are not impervious to fluid migration particularly after they have been bent. The inner liner is impermeable to fluids and thereby isolates the load carrying layers from the drilling fluids passing through the flow bore of the liner. An inner liner also serves as a mandrel for the application of the load carrying layers during the manufacturing process for the composite umbilical.
The load carrying layers are preferably a resin fiber having a sufficient number of layers to sustain the required load of the work string suspended in fluid, including the weight of the composite umbilical and bottom hole assembly.
The fibers of load carrying layers are preferably wound into a thermal setting or curable resin. Carbon fibers are preferred because of their strength, and although glass fibers are not as strong, glass fibers are much less expensive than carbon fibers. Also, a hybrid of carbon and glass fibers may be used. Thus, the particular fibers for the load carrying layers will depend upon the well, particularly the depth of the well, such that an appropriate compromise of strength and cost may be achieved in the fiber selected. Typically an all carbon fiber is preferred because of its strength and its ability to withstand pressure.
Load carrying fibers provide the mechanical properties of the composite umbilical. The load carrying layers are wrapped and braided so as to provide the composite umbilical with various mechanical properties including tensile and compressive strength, burst strength, flexibility, resistance to caustic fluids, gas invasion, external hydrostatic pressure, internal fluid pressure, ability to be stripped into the borehole, density, i.e. flotation, fatigue resistance and other mechanical properties. Fibers are uniquely wrapped and braided to maximize the mechanical properties of composite umbilical including adding substantially to its strength.
The wear layer is preferably braided around the outermost load carrying layer. The wear layer may also be a sacrificial layer since it will engage the inner wall of the borehole and will wear as the composite umbilical is tripped into the well. A wear layer protects the underlying load carrying layers. One preferred wear layer is that of KevlarTM, which is a very strong material that is resistant to abrasion. There may be additional wear layers as required. One advantage of a distinct wear layer is that it can be of a different fiber and color, making it easy to determine the wear locations on a composite umbilical. An inner liner and wear layer are not critical to the use of a composite umbilical and may not be required in certain applications. A pressure layer may also be applied although not required.
During the braiding process, electrical conductors, data transmission conductors, sensors and other data links may be embedded between the load carrying layers in the wall of a composite umbilical. These are wound into the wall of the composite umbilical with the carbon, hybrid, or glass fibers of load carrying layers. It should be appreciated that any number of electrical conductors, data transmission conduits, and sensors may be embedded as desired in the wall of a composite umbilical.
The electrical conductors may include one or more copper wires such as wire, multi-conductor copper wires, braided wires, or coaxial woven conductors. These are connected to a power supply at the surface. A braided copper wire or coaxial cable is wound with the fibers integral to the load carrying layers. Although individual copper wires may be used, a braided copper wire provides a greater transmission capacity with reduced resistance along a composite umbilical. Electrical conductors allow the transmission of a large amount of electrical power from the surface to the bottom hole assembly through essentially a single conductor. With multiplexing, there may be two-way communication through a single conductor between the surface and bottom hole assembly. This single conductor may provide data transmission to the surface.
The principal copper conductor used for power transmission from the power supply at the surface to the bottom hole assembly is preferably braided copper wire. The braided cooper wire may be used to provide the power for a power section which rotates the bit. Braided copper wire may conduct a large voltage, such as 400 volts of electricity, from the surface, which will generate heat that must be dissipated. Braided copper wire is preferably disposed between the two outermost load carrying layers. By locating braided copper wire adjacent the outer diameter of a composite umbilical, the braided copper wire is disposed over a greater surface area of layers to maximize the dissipation of heat.
The data transmission conduit may be a plurality of fiber optic data strands or cables providing communication to the controls at the surface such that all data is transmitted in either direction fiber optically. Fiber optic cables provide a broad band width transmission and permit two-way communication between bottom hole assembly and the surface. As previously described, the fiber optic cable may be linear or spirally wound in the carbon, hybrid or glass fibers of load carrying layers.
A composite umbilical is coilable so that it may be spooled onto a drum. In the manufacturing of composite umbilical, the inner liner is spooled off a drum and passed linearly through a braiding machine. The carbon, hybrid, or glass fibers are then braided onto the inner liner as the liner passes through multiple braiding machines, each braiding a layer of fiber onto the inner liner. The finished composite umbilical is then spooled onto a drum.
During the braiding process, the electrical conductors, data transmission conductors, and sensors are applied to the composite umbilical between the braiding of load carrying layers. Conductors may be laid linearly, wound spirally or braided around the umbilical during the manufacturing process while braiding the fibers. Further, conductors may be wound at a particular angle so as to compensate for the expansion of the inner liner upon pressurization of composite umbilical. A composite umbilical may be made of various diameters. The size of umbilical, of course, will be determined by the particular application and well for which it is to be used.
Although it is possible that the composite umbilical may have any continuous length, such as up to 25,000 feet, it is preferred that the composite umbilical be manufactured in shorter lengths as, for example, in 1,000, 5,000, and 10,000 foot lengths. A typical shipping drum will hold approximately 12,000 feet of composite umbilical. However, it is typical to have additional back up drums available with additional composite umbilical. These drums, of course, may be used to add or shorten the length of the composite umbilical. With respect to the diameters and weight of the composite umbilical, there is no practical limitation as to its length.
The composite umbilical has all of the properties requisite to enable the drilling and completion of extended reach wells. In particular, the composite umbilical has great strength for its weight when suspended in fluid as compared to ferrous materials and has good longevity. Composite umbilical also is compatible with the drilling fluids used to drill the borehole and approaches buoyancy (dependent upon mud weight and density) upon passing drilling fluids down its flowbore and back up the annulus formed by the borehole. This reduces to acceptable limits drag and other friction factors previously encountered by metal pipe. Composite umbilical may be used in elevated temperatures particularly when a heat exchanger is placed on drilling platform to cool the drilling fluids circulating through the borehole.
In current practice coiled tubing is often used in conjunction with a bottom hole assembly connected to the end of the tubing string. The bottom hole assembly may include a variety of downhole tools and devices including sensors, orientation devices, motors, hydraulic rams, and steering tools. If the tubing is supporting a bottom hole assembly for drilling, the bottom hole assembly will include a drill bit and other drilling equipment. Sensors and monitoring equipment of other kinds may be located upstream of the drill bit. One consequence of the variety of equipment used in conjunction with coiled tubing string is the need for some means to conduct electrical power and signals from one end of the string to the other. In this way power and signals from the control/operating point on the surface can be sent to the bottom hole assembly at the opposite end of the string, and likewise signals from the bottom hole assembly can be transmitted to the surface. Thus composite coiled tubing may be manufactured with conductors embedded in the wall of the tubing itself. The conductors may be electrical wires, optical transmitting cables, or other forms of cabling that permit the transmission of energy or data. Electrical conductors within the coiled tubing can be connected to the bottom hole assembly at one end of the string; and at the opposite end of the string, the conductors can be connected to meters, gauges, control equipment, computers, and the like.
The transmission of signals through composite coiled tubing does present one problem, however. When two or more lengths of tubing must be joined to provide the required overall length for the particular well operation, a connector must be provided to pass the energy and/or data between adjoining lengths of coiled tubing. Such a connection must first provide a robust electrical contact between the two lengths of wire to be joined so that an uninterrupted signal may pass even in the presence of the shaking and jarring that occur during a well operation, particularly during a drilling operation. In addition the connection must provide insulation. The connected conductors must not only be insulated from the fluids and other matter in the surrounding well environment but in addition the connected conductors must be properly insulated from the other conductors within the composite tubing. Materials that are present in the well environment can be highly corrosive and destructive of electrical conductors. A common shortcoming of the existing methods for connecting composite coiled tubing is that they do not adequately meet the need for a robust and well insulated electrical connection of the electrical conductors in the joined sets of tubing.
Composite coiled tubing is subjected to bending stress both when on a reel and when being fed over the gooseneck into the injector. The injector also presents a diametrical restriction through which the composite coiled tubing must pass. Further, the connector must be spoolable with the connected lengths of composite coiled tubing onto a reel or spool requiring that the connector have a limited length. Therefore, a connector joining two consecutive strings of composite coiled tubing must be able to resist the bending forces on the tubing without creating areas of stress concentration that may cause premature failure of the string. The connector must also be able to fit through the injector head, which means that the diameter of the connector is essentially limited to the diameter of the tubing, and must be spoolable, which means that the length of the connector must be of a predetermined limited length dimension. These design constraints, coupled with the preferred threaded connector that can be engaged without rotating the tubing strings, creates the need in the art for a robust, compact composite coiled tubing connector.
Notwithstanding the foregoing described prior art, there remains a need for a coiled tubing connector that combines the features of a strong mechanical connection, sealing the fluids within the coiled tubing from the outside environment, and providing a robust electrical connection. These and other features and advantages are found in the present invention.
SUMMARY OF THE PREFERRED EMBODIMENTS
The preferred embodiments of the connector provide methods and apparatus for connecting two lengths of composite coiled tubing with a connector that can be spooled with the tubing onto a reel and that will pass through an injector. Embodiments of the connector include female and male housings, each of which is connected to a length of composite coiled tubing. The housings are joined together to create the coiled tubing connection and provide mechanical and electrical or fiber optic connectivity between the two lengths of tubing. A connecting member on the male housing includes engages the female housing to connect the two housings. The housings may be aligned by splines on the male housing which align with corresponding flutes on the female housing. The female and male housings are each attached to end portions of the lengths of composite coiled tubing by a clamped connection. The connector has a length which allows it to be spoolable onto a reel with the composite coiled tubing and has an outside diameter along its length which is substantially the same as the outside diameter of the coiled tubing, thereby being substantially flush with the coiled tubing.
The present invention preferably includes lengths of a composite umbilical having an inner fluid impermeable liner, multiple load carrying layers, and an outer wear layer. The load carrying layers are preferably resin fibers braided around the inner liner. Multiple electrical conductors and data transmission conductors are embedded in the load carrying layers for carrying electric current and transmitting data between the bottom hole assembly and the surface. Also, a plurality of sensors may be mounted on one or more of the data transmission conduits along the length of the composite umbilical.
A first advantage of the connector of the present invention is that it provides a robust connection to join successive lengths of composite coiled tubing. In this way forces of compression, tension and torque can be passed along the length of composite drill string.
Another advantage of the connector of the present invention is that it provides a hydraulic seal to separate the fluids passing through the interior of the coiled tubing from fluids and materials passing externally of the coiled tubing. The connector also allows fluids to pass uninterrupted from one length of tubing to the succeeding length of tubing.
Composite tubing may not hold a perfectly round cross-section. The fact that composite tubing is flexible allows it to bend to an out-of-round cross-section. The connector of the present invention assures that the coiled tubing will be strongly bound and sealed to the connector in spite of the tubing's tendency to be out-of-round. The connector achieves this advantage by providing hydraulic seals.
A further advantage of the present invention is that the connector may be assembled without imparting rotational forces on either length of coiled tubing being connected.
A further advantage of the present invention is that it provides for a strong, well protected contact between matched pairs of electrical conductors in adjoining lengths of composite tubing. This contact is achieved through matching sets of ring contacts. The ring contact attached to the male end has a spring back located underneath the mating surface of the ring contact. Thus when the male contact ring engages the female contact ring, the spring back firmly engages the contacts.
Another advantage of the electrical contact achieved through the present connector is the insulation it provides from the surrounding well environment as well as between the neighboring electrical signals from adjacent conductors.
Another advantage of the connector is that many of the parts in the sub-assembly of the connector are the same for both the male and female pieces of the connector. Thus, there is no need for additional designs, drawings, or inventory. The same part may be used for construction of either the male or female housing.
A still another advantage of the connector is its preferred dimensions. The connector has an outer diameter which is substantially the same as the diameter of the composite coiled tubing allowing the connector to be spoolable onto a reel and to pass through an injector for the tubing. Further, the connector has a limited length such that the connector can be spooled around a reel with the composite coiled tubing.
Thus, the present invention comprises a combination of features and advantages that enable it to overcome various problems of prior art coiled tubing connectors. The various characteristics described above, as well as other features, objects, and advantages, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments of the invention, and by referring to the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
For a detailed description of a preferred embodiment of the present invention, reference will now be made to the accompanying drawings, which form a part of the specification, and wherein:
FIG. 1 is a cross-sectional view of a connector connecting two lengths of composite tubing;
FIG. 2 is a cross sectional view of the male housing of the connector;
FIG. 3 is a cross-sectional view of the female housing of the connector;
FIG. 4 is a cross-sectional view of the clamping sub-assembly of the connector;
FIG. 5 is a cross-sectional view of the female end piece of the connector;
FIG. 6 is a cross-sectional view of the male end piece of the connector;
FIG. 7 is a cross-sectional view of a split ring wedge;
FIG. 8 is a cross-sectional view of an alternative embodiment of the connector;
FIG. 9 is a schematic side view of a coiled tubing junction under bending load on a reel;
FIG. 10 is a cross-sectional view of an assembled spoolable connector assembly connecting two lengths of coiled tubing and FIG. 10A is an enlarged view of the assembly of FIG. 10;
FIG. 11 is a cross-sectional view of the male housing of the spoolable connector of FIG. 10 and FIG. 11A is an enlarged view of the male housing of FIG. 11;
FIG. 12 is a cross-sectional view of the female housing of the spoolable connector of FIG. 10 and FIG. 12A is an enlarged view of the female housing of FIG. 12; and
FIG. 13 is a cross-section view of alternative male and female housings of a spoolable connector.



DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein will be described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein.
The coiled tubing connector of the present invention includes a female housing and a male housing which join together to create the coiled tubing connection. The female and male housings each attach to an end portion of a length of coiled tubing through a clamp connection. A connecting member on the male housing engages the female housing to connect the two housings. The connecting member may be a rotating ring having threads that engage corresponding threads on the female housing. Splines on the male housing also align with corresponding grooves on the female housing. Passageways or conduits within the female and male housings also allow electrical conductors embedded within each length of coiled tubing to pass to ring contacts. Ring contacts on both the female and male housings also align when the housings are connected so as to allow electrical energy or signals to pass from one length of coiled tubing to the next.
Referring initially to FIG. 1, there is shown one preferred embodiment of a connector 10 for connecting adjacent lengths 12, 14 of composite coiled tubing. The connector 10 comprises a male housing 20 and female housing 40.
Referring now to FIG. 2, the male housing 20 is generally in the form of a hollow cylinder having a flow bore therethrough. Moving generally from right to left in FIG. 2, several features of the male housing are shown. Splines 28 are machined on or affixed onto an exterior edge of the male housing. An inner electrical contact 50 is also positioned on male housing 20. Inner electrical contact 50 is generally cylindrical in shape and includes both electrical contacts or rings 51 and wiper seals 52. Inner electrical contact 50 generally rests on the outer radius of male housing 20. Contact rings 51 are composed of any electrical conductor, and wiper seals 52 are composed of an electrical insulator.
Still referring to FIG. 2, a connecting member, such as rotating ring 27, is positioned on male housing 20. Rotating ring 27 rotates freely around the barrel of male housing 20; however rotating ring 27 does not slide axially along the length of male housing 20. Rotating ring 27 is prevented from sliding along the length of male housing 20 by a lock ring 30 and may be prevented by conventional mechanical devices such as splines or stops. Rotating ring 27 also includes threads 31 on its exterior surface. Rotating ring 27 includes an enlarged diameter portion 27a and at least one reduced diameter portion 27b. It can be seen in FIG. 2 that enlarged diameter portion 27a has an outer diameter substantially equal to the outer diameter of male housing 20 which in turn is substantially equal to the outer diameter of the composite coiled tubing 12.
Another feature of male housing 20 and rotating ring 27 is the presence of seals 29. In the preferred embodiment of this invention, seals 29 are positioned on the surfaces of the male housing 20 and the reduced diameter portion 27b of rotating ring 27, respectively. However, the seals could also be positioned on female housing 40. The seals themselves are composed of an elastomeric material that will allow a compression seal to form against the hydraulic pressures encountered in the well. As shown, seals 29 may be positioned into grooves, recesses or rings positioned on the male housing 20 and rotating ring 27.
Referring now to FIG. 3, female housing 40 is shown. Like male housing 20, the female housing 40 is also generally cylindrical in form having a flow bore therethrough. Female housing 40 includes slots or grooves 48 and receiving threads 41. Female housing 40 also has sealing surfaces 49 and outer electrical contact 60, both positioned on the internal diameter 40a of female housing 40.
Outer electrical contact 60 is generally cylindrical in shape and includes outer electrical plates or rings 61. In a preferred embodiment, the outer electrical contact 60 contains an outer electrical ring 61 for each conductor on the inner electrical contact 50. Contact rings 61 may be composed of any conducting material. Outer electrical rings 61 are not separated by wiper seals but by a plastic insulator, not shown. Outer electrical contact 60 is positioned on the inner radius of female housing 40. Electrical rings 61 are connected to conductors embedded in composite tubing 14 that is joined to female housing 40.
Both male housing 20 and female housing 40 share many common features. For ease of discussion, these common features are identified below together.
Referring again to FIGS. 2 and 3 there is shown a passage 71 and conforming seal 72. The conforming seals 72 are composed of an elastomeric material that will allow a compression seal to form under hydraulic pressure.
Both male and female housings include axial passageways 73. These passageways are hollows or grooves, approximately of the diameter or clearance of an electrical wire. The passageways may take any of several shapes depending on the ultimate shape of the connector 10 and the chosen method of manufacture.
In a preferred embodiment, the male housing 20, female housing 40, and rotating ring 27 have a plurality of apertures 32, 34, and 42 drilled into each member.
Both male housing 20 and female housing 40 include an outer conical housing 43 and inner skirt 44. Encircling inner skirt 44 on both male and female housings is split ring wedge 45. In a preferred embodiment, the outer diameter of split ring wedge 45 is straight and the inner diameter is tapered. The conical housing 43 has a straight outer diameter and a tapered inner diameter. The inner skirt 44 has a straight inner diameter and a tapered outer diameter. The split ring wedge 45 itself is manufactured from a material that shows strength at high stress and yet is relatively flexible. Beryllium copper has been used as a suitable material. The other components of both the female and male housing 40, 20 are constructed of any high strength material, such as steel, and preferably of a material that will resist corrosion.
Referring still to FIGS. 2 and 3 there is shown a transition 53, 54 in the internal diameter of male and female housings 20, 40.
In a preferred embodiment the inner electrical contact 50 and outer electrical contact 60 each have four contact plates or rings 51, 61. This number is selected as it corresponds to the number of conductors disposed in the typical coiled tubing 12, 14 in use. A different number of contact rings may be used. Both inner electrical contact 50 and outer electrical contact 60 may contain wiper seals such as seals 52. Wiper seals, formed of an elastomeric insulating material, create ridge-like separations between electrical contacts 51, 61. In a preferred embodiment wiper seals are only present on inner electrical contact 50 and not on outer electrical contact 60.
Also shown on FIGS. 2 and 3 are caps 36, 46 positioned on the male and female housings. These caps are not part of the assembled connector; however, they are attached to each housing during manufacturing to allow for handling and to prevent foreign matter from entering and possibly damaging the housings. In a preferred embodiment, the structure of both the male and the female housings 20, 40 may consist of separate parts that assemble into the final housing.
Referring now to FIG. 4, a clamping sub-assembly 80 includes pieces of both the male and female housing and may be converted into either a male housing or a female housing by the assembly of additional parts. A skirt or liner support 81 is shown as a separate piece of the clamping sub-assembly 80. The liner support 81 is joined to the body of the clamping sub-assembly 80 through a suitable fastener such as a threaded connection or a pressed fitting. Joining the clamping sub-assembly 80 to the liner support 81 are metal and plastic seals 82, 83, which themselves contain o-ring elastomeric seals 84. FIG. 4 also shows a stop clamping ring 85 forming a separate part of the clamping sub-assembly 80. The stop clamping ring 85 forms an underlying structure upon which the outer conical housing 43, inner skirt 44, and split ring 45 are mounted.
Referring again to FIG. 3, the clamping sub-assembly 80 further includes a wire guide sleeve 86 and adapter 87. FIG. 3 also shows the clamping sub-assembly 80 further converted to the final female housing 40 through the addition of a female retainer sleeve 88 and female end piece 89. FIGS. 5 and 6 provide a detailed views of female retainer sleeve 88 and female end piece 89. Similarly, FIG. 2 shows the clamping sub-assembly 80 converted into the male housing 20 through the addition of male end-piece 90 and rotating ring 27.
The assembly of male housing 20 and female housing 40 creates the complete connector 10. Assembly of the male and female housings 20, 40 begins by aligning splines 28 located on the male housing 20 with the grooves 48 located on female housing 40. The female housing 40 is constructed with an inner diameter at one end, and the male housing is constructed with a reciprocal outer diameter, so that said male housing 20 may sealingly engage the female housing 40 in assembly.
When male housing 20 is connected to female housing 40, the reduced diameter portion 27b with the threads 31 of rotating ring 27 is received within the bore of female housing 40 to engage the receiving threads 41 of female housing 40. Rotating ring 27 is then rotated by engaging the apertures 34 in enlarged outer diameter portion 27a so that threads 31 threadingly lock into receiving threads 41. Because rotating ring 27 freely rotates around the barrel 33 of male housing 20, the male housing 20 and female housing 40 do not themselves rotate upon the rotation of rotating ring 27. In this way, the male housing 20 may be firmly connected to the female housing 40 without imparting any twisting or torsional forces on the lengths of composite coiled tubing 12, 14 that are connected to male and female housings 20, 40.
The plurality of apertures 31, 34 and 42 drilled into male housing 20, female housing 40, and rotating ring 27 assist in the connection of male housing 20 to female housing 40. Apertures 32, 34, and 42 in housing 20, ring 27 and housing 40, respectively, include projections from a connection tool (not shown) used to join the lengths 12, 14 of composite coiled tubing at the job site. The engagement allows the connection tool to engage, grasp or manipulate male housing 20, female housing 40, and rotating ring 27. During the assembly step, male housing 20 and female housing 40 are held stationary through use of apertures 32 and 42. At the same time the rotating ring 27 is rotated, through use of apertures 34, so as to join male housing 20 to female housing 40 as described above.
Although apertures 32, 34, 42 have been described for engaging a connection tool, it will be apparent that other methods may be used. For example the apertures 32, 34, 42 may have various shapes. Likewise, instead of apertures, flats may be machined onto these members so as to allow wrenching tools to apply forces at these flats. In addition, chains or frictional tools may be applied to non-machined, smooth surfaces on male housing 20, female housing 40, and rotating ring 27 to apply the necessary gripping forces.
Seals 29 present on male housing 20 and rotating ring 27 are compressed onto corresponding sealing surfaces 49 on female housing 40 when male housing 20 is joined to female housing 40. In this manner the assembled connector 10 provides a fluid-tight seal that isolates fluids in the interior of the coiled tubing 12, 14 from the fluids around the outside of the coiled tubing 12, 14. Seals 29, 37 are placed on male housing 20 and rotating ring 27 for ease of manufacturing and could be equally positioned on female housing 40.
Attachment of the coiled tubing 12, 14 to the connector 10 is similar for both the male and female housings 10, 40. Referring again to FIGS. 2 and 3, there is shown lengths 12, 14 of composite tubing joined to male housing 20 and female housing 40. Male and female housing 20, 40 include an outer conical housing 43 and inner skirt 44. Encircling inner skirt 44 is split ring wedge 45. As can be seen, the end of composite tubing 14 is fitted around split ring wedge 45 and inside the inner radius of outer conical housing 43. As the outer conical housing 43 is drawn against the inner skirt 44, composite tubing 14 is compressively clamped in place against ring wedge 45. Additionally, split ring wedge 45 will be drawn tightly against the composite tubing 14 as the outer conical housing 43 is compressed against inner skirt 44.
Referring again to FIG. 4, one preferred embodiment of a clamping sub-assembly 80 includes a pressed, or swaged, connection to the composite coiled tubing 14. In some embodiments, it is preferable to install sub-assembly 80, which is common between the male and female housing assemblies, before the male or female housing components are installed. In general, sub-assembly 80 is assembled in the following manner. First, a portion of the composite coiled tubing 14 is removed to expose the embedded wires. Taper 56 is then machined into the end of the composite coiled tubing 14. Once machining is complete, liner support 81, seals 82, 83, 84, and stop clamping ring 85 are inserted into the open bore of the tubing 14. Next, outer conical housing 43 is installed on taper 56 and split ring wedge 45 is installed on stop clamping ring 85. An installation tool (not shown) can then be used to push inner skirt 44 into position between taper 56 and split ring wedge 45. The installation tool may use hydraulic force to assist in the installation of inner skirt 44. Once inner skirt 44 is fully installed, the tool is removed and wire guide sleeve 86 is connected to stop clamping ring 85 and held in place by retainer nuts 91. The wire leads from the composite coiled tubing 14 are run through slots in the stop clamping ring 85 and wire guide sleeve 86. Male or female assemblies can then be installed as desired.
In practice it may be advantageous to affix male housing 20 and female housing 40 to the ends of the composite coiled tubing at the factory, job site, or other work site. In that way lengths of coiled tubing that are pre-assembled with connector ends may then be shipped to the job site. At the job site the male and female portions of the connector may then be joined as needed.
Frictional forces hold the conical housing 43, inner skirt 44, and composite tubing together. In practice clamping forces are achieved such that the strength of the tubing-to-housing bond exceeds the strength of the coiled tubing itself.
When assembling the conical housing 43, inner skirt 44, and split ring wedge 45 to the composite tubing, it is beneficial to cut a taper 56 on the end of the composite tubing 12, 14. The tapers on the conical housing 43, inner skirt 44, split ring wedge 45, and the composite tubing 12, 14 are preferably of approximately the same degree in order to achieve a firm connection. A preferred degree of taper is approximately 11⁄2 degrees.
Referring now to FIG. 7, there is shown a preferred split ring wedge 45 that is generally cylindrical in shape. The wall thickness of split ring wedge 45 tapers from one end to the other. Further the degree of taper is such that when positioned around inner skirt 44, the inner surface 47 of split ring wedge 45 will bear at all points of surface 47 against inner skirt 44. The outer surface 49 of split ring wedge 45 will also press at all points against composite tubing 14 so as to clamp composite tubing 14 against the inner bearing surface of outer conical housing 43. Split ring wedge 45 does not form a continuous cylinder shape, however. A split 46 runs along the length of split ring wedge 45. The split 46 allows split ring wedge 45 to compress as outer conical housing 43 compresses against inner skirt 44. An identical method is used to join the composite tubing to the male housing 20 as that just described with respect to the joining the composite tubing to the female housing 40. Thus, the composite tubing is likewise joined to the male housing 20 through a friction joint including an outer conical housing 36, an inner skirt 37, and a split ring wedge 38.
As previously stated, when the coiled tubing lengths 12, 14 are connected to female and male housings 40, 20, it is advantageous to taper the end of the coiled tubing that is to be connected. When forming the taper on the end of the coiled tubing, it is also preferred to strip out a working length of the embedded conductors. The conductors are first passed through axial passageways 73, shaped into the female and male housings 40, 20, that allow the conductor to pass from the end of the coiled tubing to the inner electrical contact 50 and outer electrical contact 60.
In a preferred embodiment, the conductors from the composite tubing 12, 14 are not connected directly to the inner electrical contact 50 or the outer electrical contact 60. Rather the contact plates or rings 51, 61 of both the inner electrical contact 50 and outer electrical contact 60 are manufactured with separate conductor leads (not shown). These leads are themselves drawn through passageways 73 in male and female housings 20, 40. During assembly the conductors originating from the coiled tubing are connected or soldered to the lead conductors originating from the contact plates 51, 61. This conductor-to-conductor connection is then covered by a pressure boot (not shown). A pressure boot is essentially an elastomeric seal that keeps out fluids from the conductor-to-conductor contact by pressure means. Pressure boots are known in the industry.
Inner electrical contact 50 and outer electrical contact 60 are positioned on male and female housings 20, 40, respectively, so that when male housing 20 is joined to female housing 40 to form connector 10, the electrical rings 51 of inner electrical contact 50 match up and make electrical contact with outer electrical rings 61 disposed on outer electrical contact 60. Either or both inner electrical contact 50 and outer electrical contact 60 may have a spring back or biasing members that act to hold inner electrical contact 50 and outer electrical contact 60 in firm contact with each other.
Each contact ring 51, 61 is mounted radially and is positioned to mate with a corresponding ring 51, 61. There is an advantage to having the rings 51, 61 mounted in a radial position in that the electrical contact does not then depend on the relative radial positions of male and female housings 20, 40. Rather, it is the relative axial position of both male and female housings 20, 40 that assures the proper alignment and contact between each contact ring 51, 61. Thus, the inner and outer contacts 51, 61 are positioned to align when in the axial position that is achieved when male and female housings 20, 40 are completely connected. There is no need to position the housings 20, 40 in a particular radial position in order to achieve an electrical contact.
The wiper seals 52 found on the inner electrical contact 50 serve a function during assembly. The dimensions of the male and female housing diameters are such that during their assembly into the connector 10, wiper seals 52 are partially compressed. Further, assembly of male and female housings 20, 40 drag the partially compressed wiper seals 52 across the electrical contacts rings 61 of outer electrical contact 60. This dragging action serves to wipe the contact rings 61 clean of any contaminating material, thus assuring a clean mating surface for inner and outer electrical contacts 50, 60.
In operation, once male housing 20 is firmly joined to female housing 40, the assembled connector 10 passes forces of tension and compression up and down the coiled tubing string. In this way successive lengths 12, 14 of coiled tubing may be drawn into the well or extracted from the well. When splines 28 are engaged with grooves 48, torsional forces, in one length of tubing are passed to the connected length of another tubing.
The assembled connector 10 also provides a sealed passage for the fluids that are conducted in the coiled tubing and through the flow bores of the male and female housings 20, 40. During assembly, seals 29 sealingly engage with receiving surfaces 49. Thus the fluids can pass up and down successive lengths 12, 14 of coiled tubing, through the connector 10, without contacting the materials on the exterior of the coiled tubing.
Referring again to FIG. 1, transitions 53, 54 in the internal diameter of male housing 20 and female housing 40 respectively of the connector 10 direct the fluid as the fluid passes from one length of the coiled tubing and into the connector 10. The fluid encounters a gradual tapered decrease in the internal diameter of the connector 10 as it enters and as the fluid passes out of the connector 10 to another length of the coiled tubing, the internal diameter gradually increases. Thus the taper assists with fluid flow. The gradual taper in the connector 10 reduces turbulence in the flowing fluid. The reduced fluid turbulence serves the added benefit of reducing harm or damage to the interior of the connector 10.
Referring again to FIGS. 2 and 4, inner skirt 81 extends for some distance along the inner diameter of the coiled tubing. The purpose of the extended length of the inner skirt 81 is to provide a support on which the coiled tubing can rest. The support will reduce the stress in the coiled tubing from flexing at the point where the coiled tubing is attached to female housing 40. The length of the inner skirt 44 is preferably from between 1 to 20 times the diameter of the coiled tubing.
Referring again to FIGS. 2, 3, and 4, there is shown a passage 71 and conforming seal 72. Passage 71 allows fluid communication between the interior of composite tubing 12, 14 and conforming seal 72. Conforming seal 72 is made of a deformable material such as rubber or an elastomer. Thus, when fluid in the interior of the coiled tubing flows into passage 71, pressure in the fluid will fill conforming seal 72. In this manner conforming seal 72 acts to seal coiled tubing against the male and female housings 20, 40.
Electrical signals are transmitted through the conductors embedded in coiled tubing 12, 14. These conductors pass through passageways 73 in male housing 20 until they make electrical contact with electrical contact rings 51 of inner electrical contact 50. At this point, the electrical signals, or electrical energy if the cables are energy-carrying conductors, pass from inner electrical contact 50 to outer electrical contact 60. The signals are further transmitted through the female housing 40 through the passageways 73 in the female housing 40 and on into the cables of the coiled tubing 14 that is attached to the female housing 40.
Wiper seals 52 also serve to isolate and insulate the contact rings 61 from the fluids and other materials that are either outside the composite tubing 12, 14, or being conducted inside the composite tubing 12, 14. Thus wiper seals 52 protect the contact rings 51, 61 from chemical corrosion and physical decay. By insulating the metal plates or rings 51, 61, wiper seals 52 also assure that an uninterrupted contact is maintained between the conducting conductors of the upper and lower lengths 12, 14 of the coiled tubing. Finally wiper seals 52 also act to insulate individual electrical rings 51, 61 from each other. Thus no signal interference or power loss occurs as a result of crossed or fouled connections among the electrical plates.
Referring now to FIG. 8, there is shown an alternative connector 150 for connecting adjacent lengths 152, 154 of composite umbilical. A jet sub 160 may be disposed in connector 150 as hereinafter described. Connector 150 includes a female end connector 156 mounted on composite umbilical length 152 and a male end connector 158 mounted on composite umbilical length 154. Describing end connector 158 in detail, end connector 158 includes an end face 159, an outside tubular housing 162 and an inner tubular skirt 164 forming an annular area 166 for receiving a plurality of load carrying layers 134. As can be seen, inner liner 132 extends through inner tubular skirt 164. One or more pins 168 extend through housing 162, load carrying layers 134, and inner skirt 164 for connecting end connector 158 to the terminal end of composite umbilical length 154. Other types of connectors are shown in U.S. Pat. Nos. 4,844,516 and 5,332,049, both incorporated herein by reference.
A plurality of connectors 170 are provided in the end face 159 of end connector 158 for connection to electrical conductors and data transmission conductors housed between load carrying layers 134. Connectors for fiber optic cables are described in U.S. Pat. Nos. 4,568,145; 4,699,454; and 5,064,268, all incorporated herein by reference. A connector for coaxial cable is shown in U.S. Pat. No. 4,698,028, incorporated herein by reference. For electrical conductors in tubing, see U.S. Pat. No. 5,146,982, incorporated herein by reference. Another type of fiber optic connector is manufactured by Dean G. O'Brien of California.
Connector 150 is a quick connect connector. One type of quick connection is the bayonet type connection shown in FIG. 8. The male end connector 158 includes a plurality of arcuate segments 172 having a outwardly projecting tapered surface 174 adapted for mating with female connector 156 having a plurality of arcuate segments 176 with an inwardly directed and tapered flange 178. In operation, the segments on male end connector 158 are inserted between the segments 176 on end connector 156 and then end connector 158 is rotated with tapered surfaces 174, 178 drawing the two end faces 157, 159 of end connectors 156, 158 together. The end face of female end connector 156 includes a plurality of high pressure sealing members 179 which sealingly engage the end face 159 of male end connector 158. Upon full engagement of end connectors 156, 158 to form connector 150, the connectors 170 for electrical conductors and data transmission conductors are in alignment and are connected for transmission of electrical current or data. It can also be seen in FIG. 8, that the connector has an outer diameter which is substantially the same as the outer diameter of the coiled tubing 152, 154 thus allowing the connector to pass through an injector and be spooled onto a reel. It further can be seen that in FIG. 8 that the length of the connector has a length dimension which allows the connector to be spooled onto a reel as hereinafter discussed in further detail.
It should be appreciated that end connectors 156, 158 are preferably mounted on the ends of a composite umbilical during the manufacturing process and therefore are already mounted on the ends of the umbilical upon transport to the drilling site. It should also be appreciated that the end connectors 156, 158 need not be made of metal but may be made of a composite. A composite end connector could be heat bonded to the end of the composite umbilical. Also, it should be appreciated that other types of quick connections could be used such as the type of quick connection used for high pressure hose connections.
One alternative to the individual connectors 164, 166 for conductors are communication links which electromagnetically transmit signals around the connections rather than go through connector 150. See U.S. Pat. No. 5,160,925, incorporated herein by reference. It is preferred, however, for the conductors to be directly connected together at connection 150.
Referring again to FIG. 8, a reverse jet sub 160 may be disposed between the end connectors 156, 158 of connector 150. Jet sub 160 includes a plurality of ports 161 communicating with the flowbore and a nozzle 163 in each port 161 extending to exterior of jet sub 160 at an upstream angle. A valve 165 is also disposed in each port 161 for controlling the passage of fluid through ports 161. Valves 165 may be controlled from the surface. As the cuttings from a bit travel up the annulus, they may tend to concentrate in the annulus and fail to flow to the surface. Reverse jet sub 160 allows hydraulic fluid to pass through nozzle 163 to form fluid jets to force the cuttings up past the shoe of the cased borehole where friction is reduced and the cuttings are allowed to flow to the surface. Reverse jet subs 160 may be disposed at each connection 150 to sweep the cuttings up the annulus so that they can be flowed to the surface.
The composite umbilical is not required to withstand a great amount of tension or compression. As the drilling fluids pass down the flowbore 146 and up the annulus, the drilling fluids provide a buoyancy to the composite umbilical thereby reducing the tension and compression placed on the composite umbilical. Further, since composite umbilical does not rotate within the borehole, the composite umbilical is isolated from any reactive torque from bottom hole assembly.
The composite umbilical also has sufficient tensile and compression strength to withstand most extraordinary conditions during drilling. For example, if the bottom hole assembly becomes stuck in the well, the composite umbilical has sufficient tensile strength to withdraw the stuck bottom hole assembly in most situations. Further, if the bottom hole assembly is run into a producing well, the composite umbilical may be run in against the pressure of the producing well which applies compressive loads as the result of hydrostatic or formation pressures. This sometimes occurs in a workover well to be restimulated to enhance production. The composite umbilical will have internal pressure from the drilling fluids so as to balance the external well pressure as well as adequate collapse strength.
Various types of data may be transmitted to the surface utilizing the data transmission conduits in the composite umbilical. Some of the types of data which may be transmitted to the surface include inclination, azimuth, gyroscopic survey data, resistivity measurements, downhole temperatures, downhole pressures, flow rates, rpm's of the power section, gamma ray measurements, fluid identification, formation samples, and pressure, shock, vibration, weight on bit, torque at bit, and other sensor data. The bottom hole assembly, for example, may include a pressure sub for sensing the pressure in the annulus of the borehole.
The data transmission conduit is preferably fiber optic cable. Fiber optic cable has a very large band width allowing the transmission of large amounts of data which then can be processed by powerful computers at the surface. Using fiber optic cable, the data transmission rates are fast and a greater amount of data can be transmitted. By processing the data at the surface, the bottom hole assembly is much less expensive and is much more efficient. The ability to have a high data transmission rate to the surface allows the elimination of most of the electronics of prior art bottom hole assemblies. It also enhances the reliability of transmission of the data to the surface since pulsing the data through the mud column is eliminated.
It is often desirable to construct a composite coiled tubing connector that not only is capable of withstanding the pressure, tension, and torque requirements of the composite coiled tubing system but is also capable of being reeled onto a spool or reel with the tubing string and passing through the injector head. In order to pass through most injector heads, the outside diameter of the connector must be within 5% of the outside diameter of the composite coiled tubing string. In order to be reeled with the tubing string, or spoolable, the length of the connector must be limited.
Referring now to FIG. 9, there is shown a junction of two sections of composite coiled tubing 200, 202 being subjected to bending loads, such as on a reel or gooseneck 201. Because the bending stiffness of the connector 204 is higher than the bending stiffness of the composite coiled tubing, the connector will have a bending radius 206 much greater than the bending radius 208 of the composite coiled tubing. The differences in bending radius cause reduction in local bending at the ends of the connector 204 that create stress concentrations. For a given bending radius, the stress developed within the tubing string will significantly increase with the length L of the connector as shown in FIG. 9. For the purposes of discussion, the length of the connector L, is defined as the distance between the ends of the metal housings of the male and female ends of a made-up connector. In other words, the connector length L is the length of the metal components joining two composite coiled tubing strings.
In a coiled tubing system, the minimum bending radius for which the tubing must be able to sustain will likely be determined by either the radius of the reel on which the tubing is stored or the radius of the gooseneck that is used to feed the tubing into the injector. Thus, for the purposes of discussion when the following description refers to a “known radius” it is referring to the selected minimum bending radius, which will likely be either the radius of the storage reel or the radius of the gooseneck.
For example, the connector will be subjected to bending loads when on a reel having a radius R or when moving across a gooseneck having a radius R, the relationship of tubing diameter D to radius R is preferably:




  
    
      
        
          
            D
            
              2
              ⁢
              
                
              
              ⁢
              R
            
          
          ≤
          
            0.03
            ⁢
            
              
            
            ⁢
            or
            ⁢
            
              
            
            ⁢
            
              D
              
                2
                ⁢
                
                  
                
                ⁢
                R
              
            
          
          ≤
          
            0.06
            .
          
        
        ⁢
        
          
        
      
    
    
      
        Eq
        .
        
          
        
        ⁢
        1
      
    
  




During spooling, a tension T is preferably maintained on the tubing string and can be represented by:





  
    
      
        
          0.02
          ≤
          
            T
            
              EI
              
                R
                2
              
            
          
          ≤
          0.30
        
        ;
      
    
    
      
        Eq
        .
        
          
        
        ⁢
        2
      
    
  




where E is the tubing bending modulus and I is the tubing cross-section moment of inertia. Under these bending and tension constraints, the preferable connector total length L can be represented by:





  
    
      
        
          L
          R
        
        ≤
        
          0.25
          .
        
      
    
    
      
        Eq
        .
        
          
        
        ⁢
        3
      
    
  




Therefore, in the embodiment described, the diameter D of the tubing is not more that 0.06 times the known bending radius R and the overall length L of the connector is less than 0.25 time the known radius R.

Referring now to FIGS. 10 and 10A, one embodiment of a composite coiled tubing connector 300 is shown connecting two lengths 302, 304 of composite coiled tubing. Connector 300 includes male end 310 and female end 320, each connected to a clamping sub-assembly 80 attached to the end of the composite coiled tubing. In FIGS. 10–12, for simplicity, sub-assembly 80 is shown as a single component but it is understood that the sub-assembly is likely an arrangement of components, such as that shown in FIG. 4. Connector 300 provides electrical and fluid communication and transfers tension, bending, and torque loads between the lengths of composite coiled tubing while minimizing overall length and diameter.
Referring now to FIGS. 11 and 11A, male end 310 includes male end housing 312, male spline sleeve 314, and stationary junction 316. Male end housing 312 is threadably attached to sub-assembly 80 and includes threads 313 for engaging the female end 320 and transferring tension loads through the connector 300. Male spline sleeve 314 is retained by male end housing 312 in a keyed relationship to sub-assembly 80 and includes splines 315 that interface with female end 320 to transfer torque through the connector.
Male spline sleeve 314 also includes passageways for electrical conductors to pass through and connect to stationary junction 316 by way of conductor terminals 318. Stationary junction 316 provides the electrical connection terminus in male end 310. Stationary junction 316 is preferably constructed from a non-conductive material and may preferably include one or more contact plates that allow the connection of multiple, independent electrical circuits through the junction.
Referring now to FIGS. 12 and 12A, female end 320 includes female end housing 322, female spline sleeve 324, and adjustable junction 326. Female end housing 322 is threadably attached to sub-assembly 80 and includes the threaded sleeve 323 for engaging the male end 310 and transferring tension loads through the connector 300. Threaded sleeve 323 is retained on female end housing 322 by retainer ring 327, which may be a split ring. Female spline sleeve 324 is retained by female end housing 322 in a keyed relationship to sub-assembly 80 and includes grooves 325 that interface with male end 310 to transfer torque through the connector.
Female spline sleeve 324 also includes mounting locations for conductor terminals 328 that provide a connection location for wires 329 that connect to adjustable junction 326. Adjustable junction 326 provides the electrical connection terminus in female end 320 and is preferably constructed from a non-conductive material and may preferably include one or more contact plates that allow the connection of multiple, independent electrical circuits through the junction.
Referring again to FIGS. 10 and 10A and in conjunction with FIGS. 11, 11A, 12, and 12A, one exemplary method for assembling conductor 300 will be described. For purposes of example, conductor 300 is assumed to be employed in a composite coiled tubing system having four electrical conductors embedded in the tubing. It is understood that when connecting two adjacent lengths of composite coiled tubing 302, 304, the tubing lengths will most likely not perfectly align and rotation of the tubing strings is difficult, if not practically impossible. Of course, when connecting composite coiled tubing strings having multiple electrical conductors, the corresponding conductors from each string must be connected in order to maintain connectivity throughout the tubing string.
Thus, as the tubing lengths are being brought together, the orientation of the four electrical conductors within the male end 310 is determined by observing the orientation of stationary junction 316. The orientation and corresponding identifying marks for one or more of the electrical conductors may preferably be labeled directly on stationary junction 316. Once the orientation of the electrical conductors is established on the male end 310, adjustable junction 326 can be rotated to a position corresponding with the established position of stationary junction 316. Adjustable junction 326 may preferably be locked into position via a set screw once the appropriate orientation is established.
Adjustable junction 326 is preferably connected to the embedded conductors via lengths of wire 329 that allow the junction to be rotated at least 180° in order to facilitate alignment with the stationary junction 316. The electrical contacts, i.e. the interfacing contact plates, between adjustable junction 326 and stationary junction 316 are preferably arranged such that electrical connectivity can be established when the alignment between the two junctions can be off as much as 20° in either direction.
Once the proper orientation of adjustable junction 326 is established, the male end 310 and female end 320 of connector 300 can be joined. As the ends are brought together, splines 315 on male spline sleeve 314 interface with grooves 325 on female spline sleeve 324, fixing the rotational alignment between the lengths of composite coiled tubing. Adjustable junction 326 engages stationary junction 316 establishing electrical connectivity between the two lengths of composite coiled tubing. Threaded sleeve 323 is rotated to engage threads 313 on male end housing 312. Threaded sleeve 323 rotates independently of female end 320, thus allowing the connector 300 to be made up without rotating either length of composite coiled tubing.
In some alternative embodiments, adjustable and stationary junctions may be aligned by mechanical means, as opposed to manual alignment, as the two ends are joined. Such means may include automatic alignment mechanisms capable of rotating the adjustable junction to the appropriate orientation or alignment systems that require some operator intervention but where alignment is still carried out by mechanical means.
Referring now to FIG. 13, an alternative embodiment of a connector 400 is shown. Connector 400 is similar to connector 300 in that a male end 410 and female end 420 are mounted to clamping sub-assemblies 80. Connector 400 does not have adjustable and stationary junctions but instead provides for the manual establishment of electrical connectivity between the two composite coiled tubing strings.
In the embodiment shown in FIG. 13, the electrical conductors from both composite tubing strings are terminated in individual wires or leads. The wires 419 from the male end 410 are elongated so that, as the ends 410, 420 are connected, the wires 419 are inserted into the annular area between the female end housing 422 and the female spline sleeve 424. Female end 420 has one or more ports 421 that provide access to the interior of female end housing 422 so that once the two ends 410, 420 are connected the male end wires 419 and female end wires 429 from each tubing string can be individually connected by splicing or soldering. Plugs 428 are provided to seal ports 421 after connectivity is established.
Thus, connector 400 is assembled by bring together male end 410 and female end 420. Wires 419 from male end 410 are extended from the male end and inserted into the annular area between female end housing 422 and the female spline sleeve 424. Male spline sleeve 414 is inserted into female spline sleeve 424 and threaded sleeve 423 is rotated to engage threads 413 on male end housing 412. Threaded sleeve 423 rotates independently of female end 420, thus allowing the connector 400 to be made up without rotating either length of composite coiled tubing. Connector 400 is now mechanically made-up but no electrical connectivity has been established between the tubing strings.
Male end wires 419 are now connected, such as by slicing or soldering, to female end wires 429 such that connectivity is established between the coiled tubing strings. Wires 419, 429 are accessed through ports 421 in female end housing 422. Wires 419, 429 can be partially removed through ports 421 to ease connection of the wires. The connected wires 419, 429 are then reinserted into female end housing 422. Plugs 428 are installed to close and seal ports 421 and connector 400 is fully assembled.
Regardless of the electrical connection apparatus utilized, it is desirable that the overall length of the composite coiled tubing connector be limited so as to reduce the stress created in the composite coiled tubing immediately adjacent to the connector and that the connector have substantially the same outside diameter as the coiled tubing. The outside diameter of the tubing is preferably the same as the diameter of the coiled tubing so that the tubing and connector can pass through the injection equipment or any other diametrically restricted zone.
Because the metal connector bends very little, a considerable bending stress is imparted onto the coiled tubing at the junctions at either end of the connector. The shorter the overall length of the connector, the smaller the bending stress imparted onto the tubing. The maximum length of the connector is a function of both the diameter of the composite coiled tubing and the minimum bending radius that the tubing will be subjected to. This minimum bending radius is often either the radius of the reel on which the tubing is stored or the radius of the gooseneck. Therefore, by knowing a selected minimum bending radius and a selected diameter of the composite coiled tubing, the maximum desired length of a coiled tubing connector can be determined and the connector can be designed so as to be no longer than the maximum desired length.
While a preferred embodiment of the invention has been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit or teaching of this invention. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the system and apparatus are possible and are within the scope of the invention. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims.

## Claims

1. A tubing string adapted to bend at a known radius comprising:
a first length of composite coiled tubing having one or more embedded communication lines and a diameter of not more than 0.06 of the known radius;
a second length of composite coiled tubing having one or more embedded communication lines and a diameter substantially equal to the diameter of said first length of composite coiled tubing;
a connector having an overall length of not more than 0.25 of the known radius and disposed between said first and second lengths of composite coiled tubing and adapted to transfer tension loads, torque loads, and communication signals between said lengths of composite coiled tubing;
a male end attached to said first length of composite coiled tubing and comprising a male end threaded connector; and
a female end attached to said second length of composite coiled tubing and comprising a female end threaded connector, wherein the male end threaded connector and the female end threaded connector are adapted to rotatably engage without rotating said first or second lengths of composite coiled tubing.

2. The tubing string of claim 1 wherein said connector comprises:
a male end attached to said first length of composite coiled tubing and comprising a male end communication junction; and
a female end attached to said second length of composite coiled tubing and comprising a female end communication junction, wherein the male and female communication junctions are adapted to interconnect independent of the orientation of said second length of composite coiled tubing such that the one or more embedded communication lines of said first length of composite coiled tubing correspondingly interface with the one or more communication lines of said second length of composite coiled tubing.

3. The tubing string of claim 2 wherein the female end communication junction is rotatably adjustable relative to the female end.

4. The tubing string of claim 1 further comprising means for connecting the communication lines of said first length of composite coiled tubing to the communication lines of said second length of composite coiled tubing independently of the relative orientation of said lengths of composite coiled tubing.

5. A method for connecting two lengths of composite coiled tubing having one or more embedded communication lines have an orientation about the tubing, the method comprising:
providing a male end at one end of a first length of composite coiled tubing;
providing a female end at one end of a second length of composite coiled tubing;
determining the orientation of the one or more communication lines in the first length of composite coiled tubing by observing a male end junction disposed within the male end;
rotating a female end junction disposed within the female end to align with the male end junction, wherein the female end junction is linked to the one or more communication lines in the second length of composite coiled tubing and is adapted to rotate independently of the composite coiled tubing and the female end;
threadably attaching the male end to the female end to form a connector, wherein the connector is formed without rotating either the first or second lengths of composite coiled tubing and has an overall length of less than 0.25 times a minimum bend radius of the composite coiled tubing.

6. The method of claim 5 wherein the minimum bending radius is at least the diameter of the composite coiled tubing divided by 0.06.

7. The method of claim 6 wherein the minimum bending radius is encountered at a gooseneck between a spool and an injector head.

8. The method of claim 6 wherein the minimum bending radius is encountered at a spool.

9. The method of claim 5 further comprising limiting tension applied during spooling or running the composite coiled tubing to a desired range.

10. The method of claim 9 wherein the desired range of tension T is defined by:




  
    0.02
    ≤
    
      T
      
        EI
        
          R
          2
        
      
    
    ≤
    0.30
  
  ;




wherein E is the tubing bending modulus, I is the tubing cross-section moment of inertia, and R is the minimum bending radius of the tubing.

11. A connector for connecting a first length of composite coiled tubing to a second length of composite coiled tubing, the composite coiled tubing having an outer diameter and each length having a wall with at least one electrical wire embedded therein, the connector comprising:
a first housing connected to the first length of composite coiled tubing;
a second housing connected to the second length of composite coiled tubing;
at least one connecting member rotatably disposed on one of said first and second housings and connectably engaging the other of said first and second housings while said first and second housings are stationary;
said first housing, said second housing, and said connecting member each having a diameter equal to or less than the outer diameter of the composite coiled tubing; and
means for electrically connecting the embedded wires of the first and second lengths of composite coiled tubing.

12. The connector of claim 11 wherein the composite coiled tubing has a bend radius, and upon assembly, the assembled first housing, second housing, and connecting member have a total length dimension less than 0.25 of the bend radius of the composite coiled tubing.

13. The connector of claim 12 wherein the bend radius is at least the diameter of the composite coiled tubing divided by 0.06.

14. A connector for establishing a connection between a first length and a second length of composite coiled tubing having at least one electrical wire embedded in a wall of the composite coiled tubing for extending into a well, the composite coiled tubing having an outer diameter, the connector comprising:
a male housing affixed to the first length of composite coiled tubing;
a first electrical contact disposed on said male housing and connected to the embedded wire from the first length of composite coiled tubing;
a female housing affixed to the second length of composite coiled tubing and having an aperture receiving a portion of said male housing;
a female electrical ring disposed in said aperture in said female housing and connected to the embedded wire from the second length of composite coiled tubing, said first electrical ring electrically engaging said second electrical contact upon said portion of said male housing being received by said aperture and forming an electrical connection between the embedded wires;
a mechanical connector movably disposed on said male housing to connectably engage said female housing while said male and female housings are stationary; and
said male housing, said female housing, and said mechanical connector having an outer diameter no greater than the outer diameter of the composite coiled tubing.

15. The connector of claim 14 wherein said mechanical connector has at least a part thereof received by said aperture.

16. A connector for joining lengths of composite coiled tubing for extending into a well and supplying pressurized fluids downhole to perform a downhole operation, the composite coiled tubing having an outer diameter, the connector comprising:
a first length of composite coiled tubing having at least one electrical conductor embedded within a wall of said first length of composite coiled tubing;
a second length of composite coiled tubing having at least one electrical conductor embedded within a wall of said second length of composite coiled tubing;
a first mechanical connector affixed to said first length of composite coiled tubing, and including a first electrical connector; and
a second mechanical connector affixed to said second length of composite coiled tubing and including a second electrical connector, a connecting member rotatably disposed on one of said first and second mechanical connectors and being received in the other one of said first and second mechanical connectors, said connecting member threadingly engaging the other one of said first and second mechanical connectors and connecting the first and second lengths of composite coiled tubing without rotating said mechanical connectors affixed to the sections of composite coiled tubing;
said first and second mechanical connectors being configured such that when said first mechanical connector engages said second mechanical connector the first and second length of tubing are mechanically connected and a conducting link is formed by said first and second electrical connectors between the embedded electrical conductors; and
said mechanical connectors having an outer diameter which is substantially the same as the outer diameter of the composite coiled tubing.

17. The connector of claim 16 wherein the composite coiled tubing has a minimum bending radius of at least the diameter of the composite coiled tubing divided by 0.06.

18. The connector of claim 17 wherein the combined length of said first and second mechanical connectors is less than or equal to 0.25 times the minimum bending radius.

19. The connector of claim 16 wherein the composite coiled tubing has a desired range of tension T as defined by:




  
    0.02
    ≤
    
      T
      
        EI
        
          R
          2
        
      
    
    ≤
    0.30
  
  ;




wherein E is the tubing bending modulus, I is the tubing cross-section moment of inertia, and R is the minimum bending radius of the tubing.