Abstract:
A system for deploying a power cable within a coiled tubing includes a power cable operable to power an electrical submersible pump, the power cable extendable through a coiled tubing. A plurality of anchor assemblies are spaced along a length of the power cable, each of the anchor assemblies secured to the power cable and having a gripping element. The gripping element is moveable between a retracted position and an extended position in response to an applied stimuli, wherein the gripping element is sized to engage an inner diameter surface of the coiled tubing when the gripping element is in the extended position.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of co-pending U.S. Provisional Application Ser. No. 62/334,026, filed May 10, 2016, titled “Electric Submersible Pump Cable Anchored In Coiled Tubing,” the full disclosure of which is hereby incorporated herein by reference in its entirety for all purposes. 
     
    
     BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
       [0002]    The disclosure relates generally to electric submersible pump cables, and more particularly to rig-less deployment of electrical submersible pumps having cables within coiled tubing. 
       2. Description of the Related Art 
       [0003]    Electrical submersible pumping (“ESP”) systems are deployed in some hydrocarbon producing wellbores to provide artificial lift to deliver fluids to the surface. The fluids, which typically are liquids, are made up of liquid hydrocarbon and water. When installed, a typical ESP system is suspended in the wellbore at the bottom of a string of production tubing. In addition to a pump, ESP systems usually include an electrically powered motor and seal section. The pumps are often one of a centrifugal pump or positive displacement pump. 
         [0004]    When the ESP fails, workover rigs are used to pull out the tubing and replace the failed ESP. Workover rigs are costly, especially offshore. Also, waiting time for rigs can be as long as 6-12 months, leading to significant production deferral. 
         [0005]    Technologies are being developed to allow for rig-less deployment of ESPs inside the production tubing with the power cable. When an ESP fails, coiled tubing or a wireline unit can be used to pull out and replace the failed ESP, leaving production tubing in place. In some rig-less ESP systems, the power cable must have sufficient mechanical strength to carry the weight of the cable itself as well as the ESP system, and also have the strength to handle the pull forces for system retrieval. The power cable must also be able to withstand erosion and corrosion since it is operated in the production fluids which contain H2S, CO2 and water with high concentration of chloride. In order to provide sufficient current to drive the motor of the ESP, the conductor of the power cable can be as large as AWG#2. However, the power cable needs to be as compact in size as possible. Production fluids are produced in the annulus between the production tubing inside diameter and the power cable outside diameter. A large diameter power cable that has sufficient strength for supporting and removing the ESP will reduce the flow area, increase friction and will therefore increase the size of the motor required to lift the fluids to surface. 
       SUMMARY OF THE DISCLOSURE 
       [0006]    Embodiments disclosed herein describe systems and methods for anchoring an ESP power cable inside coiled tubing so that the power cable is supported and is and protected from corrosive environments by the coiled tubing. Systems and methods of this disclosure use materials that can undergo volume or shape change under stimuli to anchor the power cable inside the coiled tubing. 
         [0007]    In an embodiment of this disclosure a system for deploying a power cable within a coiled tubing includes a power cable operable to power an electrical submersible pump, the power cable extendable through a coiled tubing. A plurality of anchor assemblies are spaced along a length of the power cable, each of the anchor assemblies secured to the power cable and having a gripping element. The gripping element is moveable between a retracted position and an extended position in response to an applied stimuli, wherein the gripping element is sized to engage an inner diameter surface of the coiled tubing when the gripping element is in the extended position. 
         [0008]    In alternate embodiments, the anchor assembly can include a split collar that circumscribes the power cable, securing the anchor assembly to the power cable. Alternately, the anchor assembly can be bonded directly to the power cable, securing the anchor assembly to the power cable. The gripping element can include a swellable elastomer and the applied stimuli can be a dielectric oil. The swellable elastomer can be bonded to a split collar that circumscribes the power cable, securing the anchor assembly to the power cable. 
         [0009]    In other alternate embodiments, the gripping element can include a shape memory polymer and the applied stimuli can be a temperature change, an electric field, a magnetic field, or light. Alternately, the gripping element can include two way shape memory effect material and the applied stimuli can be a temperature change. 
         [0010]    In yet other alternate embodiments, the anchor assembly can have an actuator, the actuator operable to move the gripping element between the retracted position and the extended position in response to the applied stimuli. The actuator can be formed of a shape memory alloy and the applied stimuli can be a temperature change, an electric field, a magnetic field, or light. The actuator can be oriented to expand and contract in a direction along an axis of the power cable to move the gripping element radially between the retracted position and the extended position. 
         [0011]    In another embodiment of this disclosure, a system for providing power to an electric submersible pump includes a coiled tubing extending within a subterranean well. A power cable is located within the coiled tubing. A plurality of anchor assemblies are spaced along a length of the power cable, each of the anchor assemblies secured to the power cable with a split collar and having a gripping element. The gripping element is secured to the split collar. The gripping element is moveable between a retracted position and an extended position in response to an applied stimuli, wherein the gripping element is sized to engage an inner diameter surface of the coiled tubing when the gripping element is in the extended position and to have a reduced outer diameter when the gripping element is in the retracted position. 
         [0012]    In alternate embodiments, the gripping element can include a swellable elastomer and the applied stimuli is a dielectric oil. The gripping element can include a shape memory polymer and the applied stimuli can be a temperature change, an electric field, a magnetic field, or light. The gripping element can alternately include two way shape memory effect material and the applied stimuli can be a temperature change. 
         [0013]    In other alternate embodiments, the anchor assembly can have an actuator that includes a shape memory alloy, the actuator operable to move the gripping element between the retracted position and the extended position in response to the applied stimuli, wherein the applied stimuli can be a temperature change, an electric field, a magnetic field, or light. The actuator can be oriented to expand and contract in a direction along an axis of the power cable to move the gripping element radially between the retracted position and the extended position. 
         [0014]    In yet another alternate embodiment of the current disclosure, a method for deploying a power cable within a coiled tubing includes providing a power cable with a plurality of anchor assemblies spaced along a length of the power cable, each of the anchor assemblies secured to the power cable and having a gripping element, wherein the power cable is operable to power an electrical submersible pump. The power cable is extended through a coiled tubing. A stimuli can be applied to the anchor assembly to move the gripping element from a retracted position to an extended position, so that the gripping element engages an inner diameter surface of the coiled tubing. 
         [0015]    In alternate embodiments, providing the power cable with the plurality of anchor assemblies can include securing the anchor assembly to the power cable with a split collar that circumscribes the power cable. The gripping element can include a swellable elastomer and applying the stimuli to the anchor assembly can include pumping a dielectric oil into the coiled tubing. Alternately, the gripping element can include a shape memory polymer and the step of applying the stimuli to the anchor assembly can include providing a temperature change, providing an electric field, providing a magnetic field, or providing a light. 
         [0016]    In other alternate embodiments, the anchor assembly can have an actuator that includes a shape memory alloy, and applying the stimuli to the anchor assembly can include applying the stimuli to the actuator to move the gripping element between the retracted position and the extended position in response to an applied stimuli. The actuator can be oriented so that applying the stimuli to the anchor assembly expands and contracts the actuator in a direction along an axis of the power cable to move the gripping element radially between the retracted position and the extended position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    So that the manner in which the above-recited features, aspects and advantages of the embodiments of this disclosure, as well as others that will become apparent, are attained and can be understood in detail, a more particular description of the disclosure briefly summarized above may be had by reference to the embodiments thereof that are illustrated in the drawings that form a part of this specification. It is to be noted, however, that the appended drawings illustrate only preferred embodiments of the disclosure and are, therefore, not to be considered limiting of the disclosure&#39;s scope, for the disclosure may admit to other equally effective embodiments. 
           [0018]      FIG. 1  is a schematic section view of a subterranean well with an ESP and coiled tubing, in accordance with an embodiment of this disclosure. 
           [0019]      FIG. 2  is a schematic section view of a power cable within a coiled tubing, in accordance with an embodiment of this disclosure, shown with the gripping elements in the retracted position. 
           [0020]      FIG. 3  is a schematic section view of the power cable within the coiled tubing of  FIG. 2 , shown with the gripping elements in the extended position. 
           [0021]      FIG. 4  is a schematic section view of a power cable within a coiled tubing, in accordance with an embodiment of this disclosure, shown with one of the gripping elements in the extended position and the other gripping elements in the retracted position. 
           [0022]      FIG. 5  is a schematic section view of a power cable within a coiled tubing, in accordance with an embodiment of this disclosure, shown with one of the gripping elements in the extended position and the other gripping element in the retracted position. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings which illustrate embodiments of the disclosure. Systems and methods of this disclosure may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout, and the prime notation, if used, indicates similar elements in alternative embodiments or positions. 
         [0024]    In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, it will be obvious to those skilled in the art that embodiments of the present disclosure can be practiced without such specific details. Additionally, for the most part, details concerning well drilling, reservoir testing, well completion and the like have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present disclosure, and are considered to be within the skills of persons skilled in the relevant art. 
         [0025]    Looking at  FIG. 1 , subterranean well  10  includes wellbore  12 . ESP  14  is located within wellbore  12  The ESP of  FIG. 1  includes a motor  16  on its lowermost end which is used to drive a pump  18  at an upper portion of ESP  14 . Between motor  16  and pump  18  is seal section  20  for equalizing pressure within ESP  14  with that of wellbore  12 . Fluid F is shown entering wellbore  12  from a formation  22  adjacent wellbore  12 . Fluid F flows to inlet  24  formed in the housing of pump  18 . Fluid F is pressurized within pump  18  and exits out of ESP  14  at outlet  26  and into wellbore  12  or a production string (not shown). Fluids would then travel up to wellhead  28  at surface  30 . Packer  32  can seal around ESP  14  between inlet  24  and outlet  26 . 
         [0026]    ESP  14  is suspended within wellbore  12  with coiled tubing  34 . Looking at  FIG. 2 , coiled tubing  34  is an elongated tubular member with central bore  36  that has inner diameter surface  38 . Coiled tubing  34  extends within subterranean well  10 . Coiled tubing  34  can be formed of carbon steel material, carbon fiber tube, or other types of corrosion resistance alloys or coatings. 
         [0027]    Power cable  40  extends through coiled tubing  34 . Power cable  40  can provide the power required to operate ESP  14 . Power cable  40  can be a suitable power cable for powering an ESP, known to those with skill in the art. Power cable  40  can be an existing cable that is readily available in the market. 
         [0028]    Anchor assemblies  42  can be spaced along a length of power cable  40 . Each of the anchor assemblies  42  are secured to power cable  40 . The number of anchor assemblies  42  and the spacing between anchor assemblies  42  can be selected so that there are sufficient anchor assemblies  42  to support the weight of power cable  40  within coiled tubing  34 , including an industry standard safety factor. As an example, some current ESP power cables weigh about 1 lbm/ft. For such a cable, anchor assemblies  42  can be spaced, for example every 50-200 ft along power cable  40 , and in certain embodiments, anchor assemblies  42  can be located every 100 ft along power cable  40 . 
         [0029]    Looking at  FIGS. 2-3 , anchor assemblies  42  include gripping element  44 . Gripping element  44  is moveable between a retracted position ( FIG. 2 ) and an extended position ( FIG. 3 ) in response to an applied stimuli. Gripping element  44  is sized so that when in the extended position, gripping element  44  engages inner diameter surface  38  to provide anchoring and support for power cable  40 . When gripping element  44  is in the extended position, power cable  40  at the location of gripping element  44  is axially static relative to coiled tubing  34   
         [0030]    When gripping element  44  is in the retracted position, gripping element  44  can have a reduced outer diameter so that gripping element  44  is spaced apart from inner diameter surface  38 . In this way, when gripping element  44  is in the retracted position, power cable  40  can move within coiled tubing  34 . When gripping element  44  is in the retracted position, with anchor assemblies  42  secured to power cable  40 , power cable  40  can be drawn or hydraulic pressured through coiled tubing  34 . When gripping element  44  is in the retracted position, with anchor assemblies  42  secured to power cable  40 , power cable  40  can also be withdrawn from coiled tubing  34 . 
         [0031]    Gripping element  44  is secured to power cable  40  with connection member  46  that allows gripping element  44  to be secured around power cable  40  without having to slide the connection means along power cable  40  from an end of power cable  40 , but instead can be added at any position along the length of power cable  40 . Gripping element  44  can be secured to the connection member  46  so that gripping element  44  is secured to power cable  40  by way of connection member. The use of connection member  46  allows for an operator to utilize a standard and readily available cost effective power cable  40 . 
         [0032]    As an example, anchor assembly  42  can include connection member  46  that is a split collar. The split collar can include two or more segments that are secured together around power cable  40 . The split collar can circumscribe power cable  40 , securing anchor assembly  42  to power cable  40 . Gripping element  44  can be secured to the split collar so that gripping element  44  is secured to power cable  40  by way of the split collar. In alternate embodiments, connection member  46  can be a bonding material and anchor assembly  42  can be directly bonded to power cable  40  by way of the bonding material. 
         [0033]    Anchor assembly  42  can be formed, in part, of materials that can undergo volume or shape change under stimuli, such as a shape memory material. Looking at the example embodiment of  FIGS. 2-3 , gripping element  44  can include a swellable elastomer. The swellable elastomer can change shape to cause gripping element  44  to move between the retracted position ( FIG. 2 ) and the extended position ( FIG. 3 ). The swellable elastomer can, for example, be bonded to a connection member  46  that is a split collar, or alternately connection member  46  can be a bonding material so that the swellable elastomer is directly bonded to power cable  40 . 
         [0034]    The swellable elastomer can be, for example, an elastomer that swells with an applied stimuli that is a hydrocarbon based fluid. The hydrocarbon based fluid can be pumped into coiled tubing  34 . The elastomer absorbs the hydrocarbon based fluid, such as a dielectric oil, swells in volume, and expands radially to create a friction against the inner diameter surface  38  of coiled tubing  34 , allowing power cable  40  to be anchored inside coiled tubing  34 . The hydrocarbon based fluid is absorbed into the swellable elastomer through diffusion. The amount of swell of is dependent on the chemistry of the elastomer and the hydrocarbon based fluid. Design changes can be made to the parameters of the swellable elastomer, such as the length of the swellable elastomer, to achieve a desired anchoring force across the anchor assembly  42 . 
         [0035]    In alternate embodiments gripping element  44  can include a shape memory polymer. Looking at  FIG. 4 , the shape memory polymer can, for example, be bonded to a connection member  46  that is a split collar, or alternately connection member  46  can be a bonding material so that the shape memory polymer is directly bonded to power cable  40 . After power cable  40  has been installed within coiled tubing  34 , spacing measurement or detection means can be used to determine the locations of the shape memory material segments within coiled tubing  34 . The detection means can include electric-magnetic, acoustic or other techniques. Stimuli such as a temperature change, electric field, electric-magnetic field, light, or others known in the art, can be applied to the shape memory polymer from outside of coiled tubing  34 . The applied stimuli can cause the shape memory polymer to expand and support power cable  40  against inner diameter surface  38  of coiled tubing  34 , providing anchoring and support to power cable  40 . 
         [0036]    In an example embodiment, the shape memory polymer can be a two way shape memory effect material that has the ability to return from a deformed state (temporary shape) to an original (permanent) shape induced by the external stimulus or trigger. As an example, the shape memory polymer can change between rigid and elastic states by way of thermal stimuli. The change takes place at what is termed as the glass transition temperature (Tg). At a temperature above Tg, the material can be deformed. The deformed shape will be maintained when the material is cooled below Tg. The material will “remember” or return to its original shape when it is heated to a temperature above Tg again. The glass transition temperature can be custom-engineered according to specific applications. 
         [0037]    The gripping element  44  having shape memory polymer can therefore be secured to power cable  40  in a deformed shape, in which the shape memory polymer has been deformed at a temperature above Tg so that gripping element  44  is in a retracted position, and then cooled with gripping element  44  remaining in the retracted position. After power cable  40  is drawn or pressured through coiled tubing  34 , gripping element  44  can be heated to a temperature above Tg so that the shape memory polymer returns to its original shape and gripping element  44  is moved to the extended position to anchor and support power cable  40  inside coiled tubing  34  (leftmost anchor assembly of  FIG. 4 ). In securing power cable  40  within coiled tubing  34 , in the embodiments of  FIGS. 2-4 , only gripping element  44  undergoes radial movement. Systems described herein therefore have minimal moving parts, which maximizes the reliability of such systems. 
         [0038]    In order to remove power cable  40  from coiled tubing  34  for repair or replacement, the two-way shape memory polymer in the extended position can be cooled down to a retracted position. Power cable  40  can then be removed from coiled tubing  34  while gripping elements  44  are in the retracted position. Due to the two-way nature of the shape memory polymer, the removal process is straight forward. By cooling the shape memory polymer, gripping element  44  can be moved to the retracted position so that gripping element  44  is spaced apart from inner diameter surface  38  and power cable  40  can be drawn out of coiled tubing  34 . The two-way memory effect material advantageously can repeatedly engage and disengage inner diameter surface  38 , as desired, in order to set, remove, and reset power cable  40  within coiled tubing  34  without damaging power cable  40 . 
         [0039]    Looking at  FIG. 5 , in an alternate embodiment, anchor assembly  42  can include actuator  48 . Actuator  48  can include a shape memory material, such as a shape memory alloy. Actuator  48  can move the gripping element  44  between the retracted position and the extended position in response to an applied stimuli. The applied stimuli can be, for example, a temperature change, an electric field, a magnetic field, light, or other common stimuli. In the example of  FIG. 5 , actuator  48  expands and contracts in a direction along axis Ax of power cable  40 . As actuator  48  expands and contracts in a direction along axis Ax of power cable  40 , gripping element  44  moves radially between the retracted position and the extended position. 
         [0040]    In the example of  FIG. 5 , actuator  48  is a spring shaped member. In the anchor assembly  42  shown on the right hand side of  FIG. 5 , actuator  48  is contracted and gripping element  44  is in the retracted position. Gripping element  44  includes slips  50  that have gripping elements, such as teeth, that can anchor and secure power cable  40  within coiled tubing  34 . When gripping element  44  is in the retracted position, slips  50  are spaced apart from inner diameter surface  38 . In the anchor assembly  42  shown on the left hand side of  FIG. 5 , actuator  48  is expanded and gripping element  44  is in the extended position. When gripping element  44  is in the extended position, slips  50  are engaged with inner diameter surface  38 , anchoring and supporting power cable  40  within coiled tubing  34 . In the example of  FIG. 5 , gripping element  44  undergoes radial movement and actuator  48  undergoes axial movement. 
         [0041]    Actuator  48  can include two-way memory effect material so that gripping element  44  can be moved between the extended and retracted positions and slips  50  can engage and then disengage inner diameter surface  38  so that power cable  40  can be withdrawn from coiled tubing  34  for repair or replacement. The two-way memory effect material can be reversed by an applied stimuli such as, for example, a temperature change, an electric field, a magnetic field, light, or other common or known stimuli, so that gripping element  44  can be moved to the retracted position so that gripping element  44  is spaced apart from inner diameter surface  38  and power cable  40  can be drawn out of coiled tubing  34 . 
         [0042]    In an example of operation, to deploy power cable  40  within coiled tubing  34  so that ESP  14  can be installed and serviced in a rig-less operation, gripping elements  44  can be secured along a length of power cable  40 . Power cable  40  can be drawn or pressured through coiled tubing  34 . A stimuli can then be applied to gripping element  44  so that gripping element  44  moves from a retracted position to an extended position and engages inner diameter surface  38  of coiled tubing  34 . Gripping element  44  can anchor and support power cable  40  within coiled tubing  34 . If power cable  40  is to be removed, gripping element  44  can be moved to the retracted position so that gripping element  44  is spaced apart from inner diameter surface  38  and power cable  40  can be drawn out of coiled tubing  34 . 
         [0043]    Embodiments of this disclosure therefore provide for the encapsulation of power cable  40  within coiled tubing  34 , allowing for rig-less deployment of ESP  14 . Coiled tubing  34  provides mechanical strength as well as physical and corrosion protection for power cable  40 , which can be used to transmit electricity from surface  30  to drive motor  16  of ESP  14 . 
         [0044]    Embodiments of the disclosure described herein, therefore, are well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the disclosure has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present disclosure and the scope of the appended claims.