Abstract:
A method of hanging a cable within a coiled tubing string includes the steps of determining a length of coiled tubing required within a well having a wellhead; determining a length of a cable required within the coiled tubing, the cable having a structural component along the length of the cable sufficient to support the weight of the cable; cutting the tubing string and installing a hanger sub in the coiled tubing string toward, the wellhead attachment section relative to the downhole end, the hanger sub comprising an inner shoulder that extends radially into the hanger sub and defines an opening; and attaching an outer shoulder to the cable and inserting the cable into the coiled tubing string until the outer shoulder of the cable engages the inner shoulder of the hanger sub such that the inner shoulder positions the cable below the outer shoulder.

Description:
FIELD 
       [0001]    This relates to a method and apparatus for supporting cables within coiled tubing. 
       BACKGROUND 
       [0002]    Coiled tubing has become a more common element for use in downhole operations, and may be used to house cables, such as, supply lines, capillary tubing, and the like, U.S. Pat. No. 6,352,113 (Neuroth), entitled “Method and apparatus to remove coiled tubing deployed equipment in high sand applications” and U.S. Pat. No. 6,143,988 (Neuroth et al.), entitled “Coiled tubing supported electrical cable having indentations” each describe different supports used to support a cable within the coiled tubing. 
       SUMMARY 
       [0003]    According to an aspect, there is provided a method of hanging a cable within a coiled tubing string. The cable has a first end and a second end. The method comprises the steps of providing a coiled tubing string having a length required within a well having a wellhead, the coiled tubing having a wellhead attachment section and a downhole end spaced from the wellhead attachment section; determining a length of a cable required within the coiled tubing string, the cable comprising an elongate structural component that extends along the length of the cable, the structural component being sufficient to independently support the weight of the cable; cutting the coiled tubing string into first and second sections and installing a hanger sub in the coiled tubing string between the first and second sections toward the wellhead attachment section relative to the downhole end, the hanger sub comprising an inner shoulder that extends radially into the hanger sub and defines an opening; attaching an outer shoulder to the elongate structural component of the cable and inserting the cable into the coiled tubing string until the outer shoulder engages the inner shoulder of the hanger sub such that the cable is hanging within the coiled tubing string below the inner shoulder; and installing the coiled tubing string in a wellhead such that the wellhead attachment section is adjacent to the wellhead and the hanger sub is below the wellhead. 
         [0004]    According to another aspect, the hanger sub may be attached to the coiled tubing such that the outer profile is in line with the outer profile of the coiled tubing 
         [0005]    According to another aspect, the cable may comprise a supply line. 
         [0006]    According to another aspect, the method may further comprise the step of attaching the second end of the cable to a downhole tool. The downhole tool may be an electric submersible pump. 
         [0007]    According to another aspect, the structural component may comprise a metal capillary tube. 
         [0008]    According to another aspect, the cable may comprise a bundle of supply lines. The hanger sub may comprise two or more apertures, at least one aperture comprising the inner shoulder that engages the elongate structural component, at least a portion of the bundle of supply lines passing through a separate aperture, the elongate structural component structurally engaging the supply lines below the hanger sub. The elongate structural component may comprise a metal capillary tube in the bundle of supply lines. 
         [0009]    According to another aspect, the cable may comprise a resistive heating element. 
         [0010]    According to another aspect, the hanger sub in the coiled tubing string may be between 1 and 50 meters below the wellhead when installed, or between 5 m and 25 m below the wellhead when installed. 
         [0011]    According to another aspect, the hanger sub in the coiled tubing string may be positioned below the wellhead end of the coiled tubing string at a depth of between 1% and 5% of the wellbore depth. 
         [0012]    According to another aspect, at least one of the shoulder of the hanger sub and the shoulder on the cable may be slotted to prevent rotation of the cable. 
         [0013]    According to another aspect, the weight of the cable may be supported solely by the hanger sub. 
         [0014]    According to an aspect, there may be provided, in combination, a cable and a length of coiled tubing string. The cable has a first end and a second end and comprises a structural component along the length of the cable. The structural component is sufficient to support the weight of the cable. The length of coiled tubing string has a wellhead end and a downhole end. The coiled tubing string has a first section and a second section connected by a hanger sub. The hanger sub comprises an inner shoulder that extends radially into the hanger sub and defines an opening. The cable has an outer shoulder capable of engaging the inner shoulder of the hanger sub, such that, when installed through a wellhead, the hanger sub is positioned below the wellhead. 
         [0015]    According to another aspect, the outer profile of the hanger sub may be in line with the outer profile of the coiled tubing 
         [0016]    According to another aspect, the cable may comprise a supply line. 
         [0017]    According to another aspect, the second end of the cable may have a downhole tool attached. The downhole tool may be an electric submersible pump. 
         [0018]    According to another aspect, the structural component may comprise a metal capillary tube. 
         [0019]    According to another aspect, the cable may comprise a bundle of supply lines. The hanger sub may comprises two or more apertures, at least one aperture comprising the inner shoulder that engages the elongate structural component, at least a portion of the bundle of supply lines passing through a separate aperture, the elongate structural component structurally engaging the supply lines below the hanger sub. At least one supply line may comprise a metal capillary tube, the metal capillary tube providing structural support to the supply lines. 
         [0020]    According to another aspect, the cable may comprise a resistive heating element. 
         [0021]    According to another aspect, the hanger sub may be installed, at a distance of between 1 and 50 meters from the wellhead end, or at a distance of between 5 and 25 m from the wellhead end. 
         [0022]    According to another aspect, the hanger sub in the coiled tubing string may be positioned below the wellhead end of the coiled tubing string at a depth of between 1% and 5% of the well bore depth. 
         [0023]    According to another aspect, at least one of the shoulder of the hanger sub and the shoulder on the cable may be slotted to prevent rotation of the cable. 
         [0024]    According to another aspect, the weight of the cable may be supported solely by the hanger sub when installed in the wellhead. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein: 
           [0026]      FIG. 1  is a side elevation view in section of a supply line hanging in a coiled tubing string. 
           [0027]      FIG. 2  is a top view of a hanger sub. 
           [0028]      FIG. 3  is a top view of a hanger sub in a particular embodiment. 
           [0029]      FIG. 4  is a side elevation view of a hanger sub. 
           [0030]      FIG. 5  is a side elevation view of an apparatus for servicing an electric submersible pump. 
           [0031]      FIG. 6  is a side elevation view of a well completion with an electric submersible pump connected to surface by a coiled tubing string and elongate supply lines within the coiled tubing string. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    An apparatus and method of positioning a cable within a coiled tubing string will be described with reference to  FIGS. 1-6  in the context of an electric submersible pump in a well with a positive well head pressure. It will be understood that the support described below may also be used in other situations as well. 
         [0033]    Referring to  FIG. 6 , well  12 , which may be a pressurized well, includes a casing  14  and a wellhead  16  mounted to casing  14 . Wellhead  16  has a sealable injection port  18 , and production ports  20 . Referring to  FIG. 5 , injection port  18  may be sealed by a blow out preventer (BOP)  32  as shown, or it may also be sealed by a valve, a plug, etc., which may be above or below the actual port  18 . Referring again to  FIG. 6 , the number of production ports  20  may vary depending upon the design of wellhead  16 . Production tubing  22  is positioned in casing  14  and is connected to wellhead  16 . Production fluids that are pumped upward by electric submersible pump  10  flow through production tubing  22  and out production ports  20  of wellhead  16 . Electric submersible pump  10  is carried by a coded tubing string  24  at a downhole end  26  of coiled tubing string  24 , and is sized such that it is able to be run through production tubing  22 . Cables, which may include a metal capillary tube  28  and other supply lines  29  as shown, are run through and enclosed within coiled tubing string  24  and connect to electric submersible pump  10 . Metal capillary tube  28  is preferably used to supply oil, while other supply lines  29  may be used for power, communication lines, control lines, instrumentation lines, resistive heating elements, and the like. The choice of cable may be such that the cable is structurally self-supporting. Alternatively, metal capillary tube  28  provides structural support to supply lines  29 . A pump-receiving housing  30 , shown in  FIG. 5 , is located above injection port  18  of wellhead  16 . The height of pump receiving housing  30  will depend upon the size of electric submersible pump  10 . Pump-receiving housing  30  is designed such that is may be sealed to the atmosphere when injection port  18  is open, and openable to the atmosphere when injection port  18  is sealed. In other words, housing  30  works with injection port  18  to ensure that well  12  is always sealed when it is pressurized. Referring to  FIG. 5 , a BOP  32  is located above wellhead  16  and below pump-receiving housing  30 . Coiled tubing injector  34  is located above pump-receiving housing  30  and, referring to  FIG. 6 , is used to control the position of coiled tubing string  24  and electric submersible pump  10  in well  12 . 
         [0034]    Referring to  FIG. 1 , metal capillary tube  28  provides structural support to supply lines  29 . As shown, this is done by attaching supply lines  29  to capillary tube  28  using clamps  31 , although it may also be done in other ways. For example, supply lines  29  and capillary tube  28  may be encapsulated together. Furthermore, supply lines  29  and capillary tube  28  may be any self-supporting cable that acts as a structural component and that may be used in downhole applications. 
         [0035]    As shown, supply lines  29  generally require structural support as the lengths of tube  28  and lines  29  may be long enough to overcome the inherent strength of lines  29  and stretch or break. Once supply lines  29  are supported by capillary tube  28  they become self-supporting. Capillary tube  28  and supply lines  29  are mounted within and supported by coiled tubing string  24 . This is done by providing coiled tubing string  24  with a hanger sub  102  that has a shoulder  104  that engages a corresponding shoulder  106  carried by capillary tube  28 . Hanger sub  102  is preferably close to surface  108 , such as between 1 meter and 50 meters below surface, such that the majority of the length of capillary tube  28  is below hanger sub  102  and coiled tubing string  24  and there will not be movement at the surface where there is required an anchor point, Alternatively, capillary tube  28  may be mounted at a position that is based on a percentage of the depth of the wellbore, such as between 1% and 5%, Hanger sub  102  is preferably a single body but may be a two-piece that can be placed around supply lines  29 . As shown, the hanger sub shoulder is integrally formed with the hanger sub. The hanger sub is welded or otherwise attached to the coiled tubing such that the outer profile is in line with the outer profile of the coiled tubing. This ensures that the coiled tubing does not have an external upset or any increased outer diameter, which allows for ease of transport and installation. The hanger sub is attached by welding or another method in such a way that it does not substantially degrade the mechanical properties of the coiled tubing and has properties that are within the specifications for the coiled tubing string as a whole. This is particularly useful in thermal applications. Where the properties including resistance to corrosion are maintained within the specifications required for the coiled tubing. 
         [0036]    Referring to  FIGS. 2 and 4 , hanger sub  102  has an opening  110  through which the cable will pass. The shoulder  106  attached to the cable will engage hanger sub shoulder  104 , positioning the cable within the hanger sub  102 . 
         [0037]    Referring to  FIG. 3 , in a particular embodiment, hanger sub shoulder  104  may have an additional opening  112  that provides a passage for an additional support cable if needed. In this embodiment the cable may have a support line such as a capillary support tube, metal wire, or rod, attached to the cable to provide structural support below the hanger sub. The support line may carry the shoulder  106  which is positioned above opening  112 , shoulder  106  engaging with hanger sub shoulder  104  at opening  112 . 
         [0038]    Referring to  FIG. 4 , hanger sub  102  is shown from a side elevation. 
         [0039]    The description above assumes a situation where both power or communication and fluid supply are connected to a downhole tool. However, this may change depending on the circumstances. For example, rather than a bundle of supply lines  28  and  29 , in some circumstances there may only be a metal capillary tube  28 , or more than one capillary tube  28 . In other circumstances, there may not be a capillary tube  28 . While a metal capillary tube  28  is useful for providing structural support, other structural members may also be provided if fluid is not required downhole, such as a metal wire or rod that are less expensive than capillary tube  28 . 
         [0040]    When one hanger sub  102  is provided, capillary tube  28  may be run in to coiled tubing string  24  without any other hindrance, and will be properly positioned once it is correctly inserted without taking any additional steps in the process. By knowing the length of coiled tubing string  24  and the length of capillary tube  28 , hanger sub  102  and outer shoulder  106  may be installed to have each end at the correct position, such as to attached to an electric submersible pump  10  as shown in  FIG. 6 , or any other downhole tool that may be run on a coiled tubing string. 
         [0041]    The above structure may be used when installing or removing an electric submersible pump  10  without having to cool well  12 . In the depicted example, in order to insert electric submersible pump  10  into a well with a positive well head pressure, injection port  18  is first sealed by closing BOP  32 . Pump-receiving housing  30  contains electric submersible pump (ESP)  10 , which is then connected to coiled tubing string  24 . Pump receiving housing  30  is then mounted to the BOP  32 . Pump-receiving housing  30  is then closed and sealed to atmosphere and BOP  32  is opened to allow electric submersible pump  10  to be inserted through injection port  18  in wellhead  16  and into well  12  by operating coiled tubing injector  34 . In order to remove electric submersible pump  10  from pressurized well  10 , the process is reversed, with coiled tubing injector  34  lifting electric submersible pump  10  through wellhead  16  and into housing  30 . BOP  32  is then closed and sealed, and housing  30  is either opened or removed from BOP  32  to provide access to electric submersible pump  10 . Electric submersible pump  10  may then be serviced or replaced, as necessary. 
         [0042]    As depicted, electric submersible pump  10  is preferably an inverted electric submersible pump, and is run off a 1¼″-3½″ coiled tubing string  24  that contains the instrumentation lines. Other sizes may also be used, depending On the preferences of the user and the requirements of the well. When compared with traditional electric submersible pumps, electric submersible pump  10  lacks the seal section, motor pothead and wellhead feedthrough. As shown, electric submersible pump  10  includes a power head  27 , motor section  38 , thrust chamber  40 , one or more seal rings  42  and electric submersible pump section  44 . Thrust chamber  40  includes two mechanical seals with a check valve (not shown), and replaces the conventional seal/protector section that separates pump section  44  and motor section  38 . The check valve in thrust chamber  40  allows the lubricating fluid supplied by capillary tube  28  to exit thrust chamber  40  and comingle with, for example, produced fluids from the well with the pump discharge from outlet ports  50 . Seal rings  42  seal against a pressure sealing seat  46  that is carried by production tubing  22 , to provide seal between inlet ports  48  and outlet ports  50 . Inlet ports  48  are in communication with downhole fluids to be pumped to surface via outlet ports  50 , which are positioned within production tubing  22 . 
         [0043]    In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements. 
         [0044]    The following claims are to be understood to include what is specifically illustrated and described, above, what is conceptually equivalent, and what can be obviously substituted. Those skilled in the art will appreciate that various adaptations and modifications of the described embodiments can be configured without departing from the scope of the claims. The illustrated embodiments have been set forth only as examples and should not be taken as limiting the invention. it is to be understood that, within the scope of the following claims, the invention may be practiced other than as specifically illustrated and described.