Abstract:
Electro coiled tubing (ECT) can be utilized to provide electrical power to equipment in wells. A long length of ECT is provided with protrusions welded on the inside of the tubing at selected intervals to form support shoulders. Anchors with a load shoulder are attached to the electrical cable enclosed in the tubing such that the load shoulder contacts the support shoulder created by the welded protrusion. The weight of the electrical cable can then be transferred to the tubing via the contact between the load shoulder and the support shoulder. The protrusions are welded to the tubing and the anchors are attached to the cable during the manufacturing process.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates in general to electro coiled tubing and in particular to the installation and manufacturing of electro coiled tubing to provide electrical power to equipment in wells. 
       BACKGROUND OF THE INVENTION 
       [0002]    Electro coiled tubing (ECT) may be utilized to provide electrical power to submersible pump equipment in wells. ECT cable is typically fabricated by laying a length of coiled tubing along a road or other surface, then pulling into the tubing an electrical cable with anchors already in place. The anchors are clamped around the electrical cables. The location of the anchors is then obtained by using electromagnetic eddy current detectors or by, an x-ray machine, or other suitable method. A dimple can then be formed on the coiled tubing below each anchor to provide a support shoulder on the interior of the coiled tubing. The dimples on the exterior of the coiled tubing are filled with weld material and the finished ECT cable is spooled up. The combination of the anchors on the electrical cable and the support shoulder on the coiled tubing allows the weight of the electrical cable to be transferred to the coiled tubing. Without this transfer of weight, the electrical cable would pull apart under its own weight. 
         [0003]    This is a labor intensive and expensive process. In addition, the length of cable that can be pulled into the tubing is limited to approximately 8000 feet due to the increased frictional drag force that can exceed the strength of the cable. 
         [0004]    A need exists for a technique that addresses the limitations and shortcomings described above. In particular a need exists for a technique to allow for ECT cable to be manufactured in a less labor intensive manner and in a manner that does not limit the continuous length of the ECT cable that can be manufactured. The following technique solves these problems. 
       SUMMARY OF THE INVENTION 
       [0005]    In an embodiment of the present technique, a long length of ECT cable, used to provide electrical power to equipment in wells, is provided with protrusions welded on the inside of the tubing at selected intervals to form support shoulders. Anchors with a load shoulder are attached to the electrical cable enclosed in the tubing such that the load shoulder contacts the support shoulder created by the welded protrusion. When the ECT cable is installed in the well, the weight of the electrical cable can be transferred to the tubing via the contact between the load shoulder and the support shoulder. 
         [0006]    During the manufacturing process, the protrusions are welded to a sheet of steel and the anchors are attached to the electrical cable such that the protrusions align with the anchors. As the sheet of steel is rolled into tubing by formers, the protrusions, the anchors, and the electrical cable are enclosed within the formed tubing. A longitudinal weld seam will close the tubing and the finished ECT will be spooled onto a reel. 
         [0007]    The welding of the protrusions during the manufacturing process allows for a relatively less labor intensive and less expensive assembly process because the support shoulders formed by the welded protrusions are aligned with the anchors on the electrical cable as the coiled tubing is being formed. In the past, the location of the anchors had to first be determined, for example, by an electromagnetic eddy current detector before the support shoulder could be formed by first dimpling the coiled tubing and then filling the dimple on the exterior of the tubing with weld material. Further, fabrication of the ECT cable in this manner does not limit the continuous length of ECT because the electrical cable does not have to be pulled into the coiled tubing. 
         [0008]    In the illustrated embodiment, a welder deposits weld material onto a sheet of steel to form a protrusion. The sheet can be placed on a former having rollers that are in contact with the longitudinal edges of the sheet. An anchor can be clamped to an electrical cable taken from a spool. The anchor is clamped such that the protrusion on the sheet of metal aligns below and in contact with a load shoulder on the anchor as the cable is placed in proximity to the sheet. The load shoulder can be at one end of the anchor or at a central portion of the anchor which has an annular recessed area to accept the load shoulder. 
         [0009]    The protrusions, the anchors, and the electrical cable become enclosed as the rollers of the former form the sheet of metal into tubing. As the tube is formed, a longitudinal weld seam is formed on the tubing. The finished ECT cable can then be spooled onto a reel and pressure tested. In addition, magnetic flux equipment can be used to check for discontinuities in the welded portions of the ECT cable. 
         [0010]    During installation of the ECT cable, the load shoulder on the anchor will contact the support shoulder formed by the welded protrusion. The weight of the electrical cable will thereby be transferred through the load shoulder and support shoulder to the coiled tubing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  shows an ECT cable section, in accordance with the invention. 
           [0012]      FIG. 2  shows an ECT cable section showing an anchor clamped around an electrical cable, in accordance with the invention. 
           [0013]      FIG. 3  shows an ECT cable section showing the interference between the welded protrusions on the interior of the coiled tubing and the anchor, in accordance with the invention. 
           [0014]      FIG. 4  shows manufacturing process of the ECT cable, in accordance with the invention. 
           [0015]      FIG. 5  shows an ECT cable section showing a load shoulder on the central portion of an anchor attached to an electrical cable, in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring to  FIG. 1 , an embodiment of the ECT cable  10  is illustrated. A length of coiled tubing  11  with a tubing inner diameter  13  and having an interior passage encloses an electrical cable  14  having a cable outer diameter  15 . An anchor  16  with an anchor outer diameter  18  and an anchor inner diameter  20  is attached to the electrical cable  14  such that a load shoulder  22  on the lower end of the anchor  16  is in contact with at least one protrusion  24  welded onto the inside of the coiled tubing  11  that protrudes into the interior passage of the tubing  11 . The protrusion  24  forms a support shoulder to transfer the weight of the electrical cable  14  to the tubing  11 . In the example of  FIG. 3 , three protrusions  24  are attached to the tubing inner diameter  13  of the cable, each  120  degrees apart from the other. Each protrusion  24  has an axis, and the axes of protrusions  24  are located in a plane perpendicular to the axis of coiled tubing  11 . The coiled tubing  11  can be formed from a sheet of steel  12  ( FIG. 4 ) and the anchor  16  and protrusions  24  can occur at selected longitudinal intervals of the ECT cable  10 . 
         [0017]      FIG. 2  shows a section of the ECT cable  10 . The anchor  16  can be comprised of two semi-cylindrical steel halves clamped around the electrical cable  14  with threaded fasteners  30 . The electrical cable  14  can have electrical conductors  32  surrounded by insulation  34  and embedded within an elastomeric jacket  36 . A metal armor  38  can be wrapped around the exterior of the elastomeric jacket  36 .  FIG. 3  also shows a section of the ECT cable  10  and shows the interference between the anchor  16  and welded protrusions  24 . Other types of anchors, other than steel halves, could be employed, such as coiled wire with bristles, as in U.S. Pat. No. 6,167,915, elastomeric clamp members as in U.S. Pat. No. 5,821,452, coiled wire as in U.S. Pat. No. 6,479,752, or helical strips. Also, it is not necessary that anchor  16  has a load shoulder  22  as long as a portion of anchor  17  engages protrusion  24  to transmit the weight of cable  10  to coiled tubing  11 . 
         [0018]    An illustration of the fabrication process of ECT cable  10  is shown in  FIG. 4 . A former or tubing fabrication machine  60  with a base  62  and rollers  64  can receive a sheet of metal  12 . As the sheet of metal  12  is moved through the former  60 , a protrusion  24  is welded onto the surface of the sheet  12  by a welder  66  and the sheet  12  is incrementally deformed by each set of rollers  64 . The rollers  64  are spaced progressively closer together to ultimately deform the sheet into cylindrical tubing  11  as it is pulled through the former  60 . 
         [0019]    As the electrical cable  14  is taken from a spool  68  and fed into the tubing  11  as it is formed, an anchor  16  having a load shoulder  22  is attached to the cable  14 . Alternatively, the anchors can be placed on the cable at predetermined spacing prior to the tube forming operation. The anchor  16  can be clamped to the electrical cable  14  and is located on the cable  14  such that a load shoulder  22  ( FIG. 1 ) at an end of the anchor  16  will be in contact with an upward facing surface of the welded protrusion  24  in the finished ECT cable  10 . This feature will allow the weight of the cable  14  to transfer to the coiled tubing  11  when the ECT cable  10  is installed within a well. Further, the anchor  16  and protrusions  24  can be installed and welded, respectively, at selected intervals in the process. Rather than forming protrusions  24  by applying weld material to the tubing inner diameter  13 , they could be preformed members that are attached to the tubing inner diameter such as by welding, bonding or with a fastener. 
         [0020]    As the sheet  12  is formed into tubing  11 , the electrical cable  14  along with the anchor  16  is enclosed within the tubing  11 . A longitudinal weld  74  can then be welded onto inside surface of the metal sheet by a seam welder  72  and the finished ECT cable  10  can then be coiled onto a reel  80 . The ECT cable  10  can then be pressure tested on the reel  80 . 
         [0021]    In another embodiment illustrated in  FIG. 5 , a different anchor can be utilized. The anchor  50  shown has a load shoulder formed by an annular recess  51  located at a central portion of the anchor  50 . The downward facing surface of the annular recess  51  acts as a load shoulder and is in contact with an upward facing surface of the welded protrusion  24  when the ECT cable  10  is installed in the well. This embodiment can support the cable  14  in either direction in the event the tubing is reversed before installing it in the well. 
         [0022]    In a further embodiment, weld material can form the protrusion  24  that extends inward into the passage of the tubing  11 . A welder can deposit sufficient weld material onto the surface of the sheet of steel  12  that forms the tubing  11  to provide a support shoulder for the load shoulder of the anchor  16 . 
         [0023]    In a further embodiment, a set of protrusions  24  can be welded in the tubing adjacent to the load shoulder of the anchor  24 . The protrusions can be disposed circumferentially around the tubing. Protrusions  24  can also be fabricated by spot welding pieces of steel to the inside of the metal sheet. 
         [0024]    In yet another embodiment, a set of protrusions can be welded onto the anchor  24  to form a load shoulder. These protrusions are in addition to the protrusions  24  welded onto the tubing and are preferably welded onto either end of the anchor  24 . 
         [0025]    Feeding the cable  14  and anchors  16  and welding the protrusions  24  onto the tubing  11  as the tubing  11  is formed reduces labor intensiveness and expense by eliminating the need for locating the anchors via electromagnetic eddy current equipment and then crimping the tubing to provide the support shoulder. Further, the length of the finished ECT cable  10  is not limited by length of the cable  14  that can be pulled because it is fed, along with the anchors  16 , into the tubing  11  as it is formed. In the example shown in the figures, the finished ECT cable  10  is only limited in length by the spool  68  and reel  80  capacities. 
         [0026]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. These embodiments are not intended to limit the scope of the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.