Abstract:
Embodiments of the present invention generally relate to a method and apparatus for providing a conductor in a tubular. In one embodiment, a coiled tubing string for use in a wellbore includes: a tubular; a conductor extending at least essentially a length of the tubular; and a tubular coating extending at least essentially the length of the tubular and bonding the conductor to an inner surface of the tubular.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. Provisional Application Ser. No. 61/229,010, filed Jul. 28, 2009, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention generally relate to a method and apparatus for providing a conductor in a tubular. 
         [0004]    1. Description of the Related Art 
         [0005]    The use of coiled tubing in the oil industry is increasing in popularity for drilling, completion, and production operations in crude oil or natural gas wellbores. Historically, strings of drill pipe were used for drilling and conducting operations inside a wellbore, usually several hundred or thousand feet under the surface of the ground. However, joints of drill pipe must be threaded together and lowered into the wellbore over a long time period of many hours or days. Coiled tubing emerged as a solution by providing a relatively fast and reliable method of conducting operations downhole within a wellbore, without using heavy and cumbersome jointed drill pipe. 
         [0006]    Coiled tubing is a continuous tubular strand traditionally made from steel possessing sufficient ductility to withstand flexing as the tubing is uncoiled from a reel for insertion into the wellbore or coiled back onto the reel for removal from the wellbore since the coiled tubing is plastically deformed onto the reel. Coiled tubing is traditionally manufactured by rolling flat strips cut from rolls of sheet steel into a tubular shape and fusion welding the seam. Recent advances include composite coiled tubing strings made from fibers embedded in a resin matrix fibers embedded in a resin matrix. The fibers, usually glass and carbon, are wound around an extruded thermoplastic tube and saturated with a resin, such as epoxy. Another recent advance is seamless steel coiled tubing which may be manufactured by extrusion. 
         [0007]    Coiled tubing is deployed using a coiled tubing unit. The coiled tubing unit includes the reel, an injector, controls, and a power pack. The injector feeds the coiled tubing into the wellbore through a stripper mounted on the wellhead. Such a coiled tubing unit is discussed and illustrated in U.S. Pat. No. 5,828,003, which is herein incorporated by reference in its entirety. 
         [0008]    Current coiled tubing applications include slim hole drilling, deployment of reeled completions, logging of deviated or highly deviated (i.e., horizontal) wellbores, and deploying treatment fluids downhole. The use of coiled tubing in highly deviated or horizontal wellbores is rapidly increasing at a rapid rate. 
         [0009]    Many of these applications would benefit from the ability to transmit and receive data and/or or transmit power from the surface. This ability could be used to monitor the properties of the coiled tubing, detect pressure and temperature inside the wellbore at the distal end and/or along the coiled tubing, monitor and/or control the operation of downhole tools mounted upon the distal end of the coiled tubing, and/or detect an exact depth of the distal end of the coiled tubing. 
         [0010]    Past attempts at transmitting data to the surface include wireless telemetry (i.e., mud pulse, electromagnetic, and acoustic). However, wireless telemetry suffers from low bandwidth (i.e., 10 bits/second), latent travel time (speed of sound for acoustic and mud pulse), and inability to transmit electricity. U.S. Pat. No. 6,717,501 to Hall discloses wired drill pipe. However, wired drill pipe suffers from the disadvantages of drill pipe, discussed above. U.S. Pat. No. 6,143,988 to Neuroth discloses a cable disposed in a coiled tubing string. However, Neuroth requires deforming the coiled tubing to support the weight of the cable and a jacket and armor to protect and support the cable. U.S. Pat. No. 5,828,003 to Thomeer discloses coiled tubing made from a composite laminate having conductive wires embedded therein. Thomeer&#39;s composite is extremely complicated to design and manufacture. U.S. Pat. No. Re. 36,833 to Moore discloses a continuous tubing having conductors enclosed by a metal strip welded to the tubing as the tubing is roll-formed and welded. U.S. Pat. No. 7,025,580 to Heagy discloses an inflatable liner bonded to a pipe with a resin and having a channel housing a cable conduit. 
         [0011]    For some of these applications, it may be desirable to coat an inner surface of the coiled tubing wall to protect the surface from corrosion or plugging. Corrosion may be caused by pumping an acidic solution through the coiled tubing in a formation treatment operation. Plugging may be caused by pumping hydrocarbon fluid through the coiled tubing in a low temperature environment, such as subsea. Byproducts, such as paraffin may condense from the hydrocarbon fluid and adhere to the inner surface of the coiled tubing. Such a coating process is discussed in U.S. patent application Ser. No. 12/388,166 (Atty. Dock. No. TUBE/0003), filed Feb. 18, 2009, which is herein incorporated by reference in its entirety. The &#39;166 application discusses a multi-cycle coating regimen including a degreasing cycle, a rinse cycle, a descaling cycle, a neutralization cycle, a drying cycle, an inhibitor cycle, and a coating cycle. The working fluid for each cycle may be applied using a pig or pigtrain. The protective coating may be a polymer, such as epoxy, polyurethane, or polytetrafluoroethylene (PTFE). 
       SUMMARY OF THE INVENTION 
       [0012]    Embodiments of the present invention generally relate to a method and apparatus for providing a conductor in a tubular. In one embodiment, a coiled tubing string for use in a wellbore includes: a tubular; a conductor extending at least essentially a length of the tubular; and a tubular coating extending at least essentially the length of the tubular and bonding the conductor to an inner surface of the tubular. 
         [0013]    In another embodiment, a tubing string for use in a wellbore includes: a tubular; a first tubular coating extending a length of the tubular and made from an electrically conductive material; and a second tubular coating extending the length of the tubular and made from an electrically insulating material. The first coating is disposed between the second coating and an inner surface of the tubular. 
         [0014]    In another embodiment, a method for bonding a conductor to an inner surface of a tubular includes: pumping a volume of coating in front of a pig; and propelling the pig through the tubular, wherein the pig applies the coating to the inner surface having at least a portion of the conductor laid thereon. 
         [0015]    In another embodiment, a method for forming a signal conductor along an inner surface of a tubular, includes: pumping a volume of coating in front of a pig; and propelling the pig through the tubular. The pig applies the coating to the inner surface and the coating is electrically conductive. 
         [0016]    In another embodiment, a spool pig for use in a coiled tubing string, includes: a nose; a tail; a mandrel connected to the nose and tail; and a spool disposed on the mandrel and rotatable relative to the mandrel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0018]      FIG. 1  illustrates a spool pig deployed in a coiled tubing string, according to one embodiment of the present invention.  FIG. 1A  is a detailed view of  FIG. 1 .  FIG. 1B  illustrates coating of the inner surface of the coiled tubing.  FIGS. 1C and 1D  illustrates the conduit bonded to an inner surface of the coiled tubing using the coating.  FIG. 1E  is a detail of an optical cable disposed in the conduit.  FIG. 1F  is a detail of an optical fiber disposed in the conduit. 
           [0019]      FIG. 2A  illustrates coating of the coiled tubing, according to another embodiment of the present invention.  FIG. 2B  illustrates the optical fiber/cable bonded directly to an inner surface of the coiled tubing using the coating, according to another embodiment of the present invention.  FIG. 2C  illustrates two fibers laid and bonded to the coiled tubing inner surface. 
           [0020]      FIG. 3A  illustrates a twisted pair cable bonded to an inner surface of the coiled tubing using the coating, according to another embodiment of the present invention.  FIG. 3B  illustrates two circumferentially spaced jacketed wires bonded to an inner surface of the coiled tubing using the coating, according to another embodiment of the present invention.  FIG. 3C  illustrates a coaxial electrical cable bonded to an inner surface of the coiled tubing using the coating, according to another embodiment of the present invention.  FIG. 3D  illustrates a single electrical wire bonded to an inner coating layer by an outer coating layer, according to another embodiment of the present invention. 
           [0021]      FIG. 4A  illustrates an electrically conductive layer disposed between two insulating layers, according to another embodiment of the present invention.  FIG. 4B  illustrates two electrically conductive layers each disposed between two insulating layers, according to another embodiment of the present invention.  FIG. 4C  illustrates an electrically conductive layer disposed between two insulating layers and having a jacketed wire bonded to an inner surface of the coiled tubing, according to another embodiment of the present invention. 
           [0022]      FIG. 5A  is a cross section of a male coupling installed at a first end of the coiled tubing, according to another embodiment of the present invention.  FIG. 5B  is a cross section of a female coupling installed at a second end of the coiled tubing.  FIG. 5C  is a cross section of connected male and female couplings. 
           [0023]      FIGS. 6A-6F  illustrate a method for splicing one of the couplings  500   f,m  to one of the coiled tubing ends  55 , according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1  illustrates a spool pig  1  deployed in a coiled tubing string  50 , according to one embodiment of the present invention. Alternatively, the spool pig  1  may be deployed in other tubular strings, such as a pipeline, reeled pipe, drill pipe, production tubing, or casing. The coiled tubing string  50  may be made from a metal or alloy, such as plain carbon steel, low alloy steel, or a corrosion resistant alloy, such as QT-16Cr, HS-80, titanium, or stainless steel. Alternatively, the coiled tubing string may be made from a composite, such as a fiber (i.e., glass or carbon) reinforced polymer resin (i.e., epoxy or PVC). The coiled tubing  50  may have a length of greater than or equal to one thousand, five thousand, ten thousand, twenty thousand, or thirty thousand feet. The coiled tubing  50  may have an outer diameter ranging from three-quarters of an inch to four inches and have a wall thickness ranging from 0.08 to one-quarter of an inch. 
         [0025]    In preparing the coiled tubing  50  for deployment of the spool pig  1 , an inlet  55   i  and outlet  55   o  of the tubing  50  may be located at or near ground level to allow for easier access. A clamp (not shown) may be secured to each of the inlet  50   i  and outlet  50   o . Each clamp may have a flange to receive corresponding flanges of a pig launcher (not shown) and a pig receiver (not shown). A suitable pig launcher and receiver are illustrated in FIGS.  1  and  9 - 11  of U.S. Pat. No. 5,230,842, which is herein incorporated by reference in its entirety. As discussed above and in the &#39;166 application, an inner surface  50   s  of the coiled tubing  50  may be treated to remove manufacturing or other debris until a white-metal or near white-metal finish, such as NACE number one or two, is achieved. 
         [0026]    To deploy the spool pig  1  into the coiled tubing  50 , the spool pig may be loaded into the launcher. Alternatively, the spool pig  1  may be launched into the coiled tubing string without using a launcher and/or receiver. Propellant P may be injected into the launcher to drive the spool pig  1  through the coiled tubing  50 . The propellant P may be a fluid, such as liquid or compressed gas, such as ambient air, dry air, or nitrogen. As the spool pig  1  travels through the coiled tubing  50 , a conduit  100  may unwind from the spool pig  1 . An end of the conduit distal from the spool pig  1  may be fastened to the inlet or the launcher. The spool pig  1  may exert tension T on the conduit  100  as the spool pig  1  travels through the coiled tubing, thereby retaining the coiled tubing along an inner curvature of the coil. When the spool pig  1  reaches the outlet  55   o , the spool pig  1  may be caught by the receiver and removed from the coiled tubing string  50 . A proximate end of the conduit  100  may be fastened to the receiver, outlet, or a tensioner (not shown). The conduit  100  may be made from a metal or alloy, such as steel or aluminum, or a polymer, such as polyvinyl chloride (PVC). 
         [0027]      FIG. 1A  is a detailed view of  FIG. 1 . The spool pig  1  may include tail  5 , a mandrel  7 , a nose  10 , a guide  12 , a tensionser  14 , and a spool  15 . The spool  15  may include a rear rim  16 , one or more bearings  17 , a front rim  18 , and a sleeve  19 . The mandrel  7  may be a rod having threaded ends and made from a metal or alloy, such as steel, or a polymer. Alternatively, the mandrel  7  may be a tubular capped at each longitudinal end thereof. The nose  5  and tail  10  may each be seals and may be retained on the mandrel  7  using fasteners (not shown) or may include a hub portion having a threaded inner surface and a disc/cone portion. The seals (or disc/cone portions thereof)  5 ,  10  may each be made from a polymer, such as polyurethane, ploychloroprene, or polyisoprene and the hub portion may be made from a metal or alloy, such as steel. The front seal  10  may be conical for guiding the pig through the coiled tubing  50 . 
         [0028]    The guide  12  may be a roller mounted to the mandrel  7  or rear rim  16  for feeding the conduit  100  from the spool  15  to the coiled tubing inner surface  50   s . The tail  5  may have a notch formed in an outer surface thereof for passage of the conduit  100 . The conduit  100  may be wrapped along the sleeve  19  and retained by the rims  16 ,  18 . The bearings  17  may each be disposed between the head  18  or tail  16  and the mandrel  7 . Alternatively, the bearings  17  may be disposed between the sleeve  19  and the mandrel  7 . The bearings  17  may longitudinally connect the spool  15  to the mandrel  7  while allowing relative rotation therebetween. The bearings  17  may be fastened to the mandrel  7  and the spool  15 . The tensioner  14  may include one or more Beliville washers engaging the front rim  18  and the nose  10  to frictionally dampen rotation of the spool  15 , thereby maintaining tension T in the conduit. The rims  16 ,  18  and sleeve  19  may be integrally formed or fastened together, such as by threaded connections. 
         [0029]    Alternatively, instead of a spool pig  1 , the spool of conduit  100  may be located externally of the coiled tubing  50  and a simple pig may be used to pull the distal end of the conduit through the coiled tubing  50 . 
         [0030]      FIG. 1B  illustrates coating of the inner surface  50   s  of the coiled tubing  50 . An interior coating may be applied to the inner surface  50   s  of the tubing  50 , having the conduit  100  laid thereon, while the tubing  50  is in place on the reel, using extruder pigs  60   a,b . A first or lead extruder pig  60   a  and a second or trail extruder pig  60   b  may be inserted into a loading chamber of the pig launcher in a spaced relationship, with fluid ports of the chamber positioned between the loaded pigs  60   a,b . A predetermined volume of the fluid coating  110  may be injected, such as pumped, into the space between the loaded pigs and the air between the pigs may be vented. After the fluid coating has been injected, propellant may be injected behind the trail pig, thereby driving the pigtrain through the coiled tubing  50 . A pressure of the propellant may be selected to control velocity of the pigtrain and coating thickness. 
         [0031]    The lead extruder pig  60   a  may include a cup  61 , a seal  63 , and one or more fasteners  64   h,s ,  65 . The cup  61  may include a wiper  61   b,s  and a hub  61   h . The wiper  61   b,s  may be molded to the hub  61   h . The seal  63  may include a disc  63   d  and one or more hubs  63   h . The disc  63   d  may be molded between the two hubs  63   h . The wiper  61   b,s,  and disc  63   d  may each be made from a polymer, such as polyurethane, ploychloroprene, or polyisoprene and the hubs  61   h ,  63   h  may be made from a metal or alloy, such as steel. The hubs  61   h ,  63   h  may be connected by a longitudinally extending fastener, such as a bolt  64   h,s  and a nut  65  engaged with a threaded shank  64   s  of the bolt. A head  64   h  of the bolt may shoulder against a base  61   b  of the wiper  61   b,s.    
         [0032]    An outer portion of the disc  63   d  may be in sealing engagement with the coiled tubing inner surface  50   s  and be solid. The wiper  61   b,s  may have a flexible, cylindrical wall or skirt  61   s , extending rearwardly from a base  61   b  connected or mounted to the bolt  64   h,s . The flexible skirt  61   s  may be expandable outwardly in response to pressure differential during movement of the pig  60   a  through the coiled tubing  50  in coating operations. When so expanded outwardly, the skirt  61   s  may define an annular front reservoir Ra between the disc  63   d  and the skirt  61   s . The skirt  61   s  and the outer portion of the disc  63   d  may be flexible enough to accommodate passage over the conduit  100 . Alternatively, the skirt and the disc may each have a notch formed in an outer portion thereof and aligned with the conduit to accommodate the conduit. The annular reservoir Ra may be filled with a volume of the coating material  110  to be applied to the interior surface of the coiled tubing  50 . The coating material  110  in reservoir Ra may be urged toward the coiled tubing inner surface under the force of the pressure moving the lead pig  60   a  through the tubing  50 , and the flared skirt  61   s  may exert a wiping blade action about its outer periphery for this purpose. One or more feed ports  61   p  may be formed through the base  61   b . The feed ports  61   p  may allow passage into the annular reservoir R of the coating material  110  from a main charge of coating material  110  transported between the pigs  60   a,b.    
         [0033]    The trail pig  60   b  may be similar to the lead pig  60   a  except that the disc  63   d  may have one or more passages or slots  63   p  formed through an outer portion thereof and the ports  61   p  may be omitted. The size and number of coating material slots  63   p  may be chosen to regulate the amount of coating material  110  which may pass rearwardly of the disc  63   d  into a rear reservoir Rb. One of the ports  63   p  may or may not be sized and aligned with the conduit  100  to accommodate the conduit  100 . The rear reservoir Rb may receive a regulated volume of coating material  110  from the main charge through the slots  63   p  as the trail pig  60   b  moves through the coiled tubing  50 . The skirt  61   s  of the trail pig  60   b  may be flexible outwardly to a position where an outer rim is spaced from the coiled tubing inner surface  50   s  to define a circumferential gap. As with the skirt  61   s  of the lead pig  60   a , the skirt  61   s  of the trail pig  60   b  may be flexible enough to accommodate passage over the conduit  100  or may have a notch formed in an outer portion thereof in alignment with the conduit to accommodate the conduit. The amount of flexure of rear pig skirt  61   s  and thus the size of the gap may be governed by the propellant pressure selected for movement of the pigs  60   a,b  through the coiled tubing  50 . The selected pressure, in conjunction with the regulated volume of coating material  110  in reservoir Rb, may be used to regulate the thickness of coating material  110  deposited on the coiled tubing inner surface  50   s.    
         [0034]    An initial volume of the main charge may be sufficient to coat a length of the coiled tubing inner surface  50   s  with a coating  110  of predetermined thickness. After the leading and trailing extruder pigs  60   a,b  have been driven through the coiled tubing  50  to the receiver, the coating layer  110  may be dried by passing a sufficient volume of dehydrated air through the tubing for a time sufficient to thoroughly dry the coating layer  110 . Depending on the specific coating material selected, the coating layer may require an additional curing step after it has been completely dried. For instance, where PTFE is used as the coating material, the tubing may be heated by unwinding the coiled tubing from the reel, through an oven, and then back onto a second storage reel. 
         [0035]    As discussed more below, it may be desirable to apply one or more additional layers of the coating, whether of the same or different coating material. After the first coating layer has been dried with dehydrated air, the extruder pigs  60   a,b , together with another quantity of coating material therebetween, may be loaded in reverse order and position into the downstream tubing section along with a new mass or charge of coating material to apply a second layer of coating. Alternatively, the extruder pigs  60   a,b  may be removed and loaded in the same order and position at the upstream loading chamber in the manner described above. The drying and/or curing process may then be repeated. Alternatively, the lead extruder pig  60   a  may be omitted and only the trail pig  60   b  may be used to apply the coating  110 . 
         [0036]      FIGS. 1C and 1D  illustrates the conduit  100  bonded to an inner surface  50   s  of the coiled tubing  50  using the coating  110 . Once dried and/or cured, the coating  110  forms a tubular lining bonded to the inner surface  50   s  and extending the length of the coiled tubing  50 . A thickness T of the coating  110  may be equal or substantially equal to an outer diameter OD of the conduit  100  so that the conduit is flush or substantially flush with an inner surface of the coating. Alternatively, the coating thickness T may be less than or substantially less than the conduit outer diameter OD, such as less than three-quarters, one-half, one quarter, one-eighth, or one-sixteenth the outer diameter OD. A portion or substantial portion of the conduit outer surface may still be covered by a protrusion  110   p  of the coating or the conduit portion may be exposed to a bore of the coiled tubing. The coating thickness T may be from a single layer of the coating or an aggregate thickness resulting from two or more layers of the coating. Each layer of coating may have a thickness ranging from 0.0005 to 0.05 of an inch and an aggregate thickness of the coating may range from 0.001 to one-quarter of an inch. 
         [0037]    In addition to bonding the conduit  100  to the inner surface  50   s , the coating  110  may serve to protect the inner surface  50   s  from corrosion, erosion, and/or plugging. The coating  110  may be made from a polymer, such as epoxy, polyurethane, or PTFE or, as discussed below, a composite, such as a metal/alloy-filled polymer. The coating  110  may be electrically insulating or electrically conductive. 
         [0038]      FIG. 1E  is a detail of an optical cable  120   c  disposed in the conduit  100 .  FIG. 1F  is a detail of an optical fiber  120   f  disposed in the conduit  100 . The optical cable may include a core  121 , a cladding  122 , a buffer  123 , and a jacket  124 . The core  121  and cladding  122  may be made from a ceramic, such as silica. The buffer  123  and jacket  124  may be made from a polymer. The fiber  120   f  may include only the core  121  and the cladding  122 . The optical cable  120   c  may include a plurality of fibers. The cable/fiber  120   c,f  may be inserted into the conduit  100  before or after the conduit  100  is boned to the coiled tubing inner surface  50   s  by the coating  110 . The cable/fiber  120   c,f  may be inserted into the conduit  100  by gravity deployment or pumping using air or fluid. Disposing the cable/fiber  120   c,f  in a conduit  100  may reduce stress exerted on the fiber/cable by changes in stress of the coiled tubing  50 , such as by unwinding/winding of the coiled tubing on the reel, exerting loads on the coiled tubing in the wellbore, or thermal expansion of the coiled tubing due to deployment in the wellbore. The stress reduction may occur because the conduit  100  is bonded to the coiled tubing  50  and the cable/fiber  120   c,f  may move relative to the coiled tubing, thereby providing a strain buffer for the cable/fiber. 
         [0039]    Once the conduit  100  is bonded to the coiled tubing inner surface  50   s  and the fiber/cable  120   f,c  is inserted through the conduit, the coiled tubing may be deployed into a wellbore, such as for a drilling operation. A BHA (not shown) including a drill bit, a mud motor, a bent sub, an orienter, and a sensor sub (i.e., MWD and/or LWD) may be connected to a distal end of the coiled tubing. The cable/conduit may be used to transmit data from the BHA to the surface, such as temperature, pressure, drill bit orientation, torque, and rotary speed of the bit. The data may be transmitted at high rates, such as one or more kilo-bits, mega-bits, or giga-bits per second. The data may also be transmitted in real time (no latency time). Additionally, the sensor sub may include logging sensors to detect formation characteristics while drilling. Communication may be bidirectional such that data is sent from the BHA to the surface and instructions may be sent from the surface to the BHA, such as to actuate the orienter. Additionally, optical power may be transmitted from the surface along the fiber/cable  120   f,c  to an additional generator sub of the BHA including one or more photovoltaic cells. The power and data may be multiplexed on a single cable/fiber or a second cable/fiber may be added for power. The generator may used to power one or more components of the BHA, such as the orienter and/or sensor sub. 
         [0040]      FIG. 2A  illustrates coating of the coiled tubing  50 , according to another embodiment of the present invention. Instead of deploying the spool pig  1  and then deploying the extruder pigs  60   a,b  in separate steps, the spool pig and extruder pigs may be deployed simultaneously in a single pigtrain. The cable/fiber  120   c,f  may also be bonded directly to the coiled tubing inner surface  50   s  without the conduit  100 . Alternatively, the conduit  100  may be deployed. Alternatively, the cable/fiber  120   c,f  may be laid and bonded directly to the coiled tubing inner surface  50   s  using separate steps. As the cable/fiber  120   c,f  is laid from the spool pig  1 , the extruder pigs  60   a,b  may immediately follow by applying the coating  110 . Alternatively, the lead extruder pig  60   a  may be omitted. Omitting the conduit  100  may allow for a thinner coat  110  to be applied. Alternatively, the cable/fiber  120   c,f  may be laid in a helical path along the inner surface  50   s  to act as a strain buffer between the cable/fiber  120   c,f  and the coiled tubing  50 . 
         [0041]      FIG. 2B  illustrates the optical fiber/cable  120   f,c  bonded directly to the coiled tubing inner surface  50   s  using the coating  110 , according to another embodiment of the present invention. When bonding the fiber directly (no conduit) to the inner surface of the coiled tubing, a thickness T of the coating  110  may be greater or substantially greater than an outer diameter OD of the fiber  100  so that the fiber is sub-flush or substantially sub-flush with an inner surface of the coating. The coating may be applied in multiple layers to accomplish the sub-flush relationship, i.e. the fiber is bonded with a first coating layer and then a second coating layer completely embeds the fiber. When bonding the optical cable directly to the inner surface of the coiled tubing, the coating thickness may be less than, equal to, or greater than the cable outer diameter OD. 
         [0042]      FIG. 2C  illustrates two fibers laid and bonded to the coiled tubing inner surface  50   s . A first cable/fiber  220   a  may be directly bonded to the surface  50   s  and a conduit  100  may be bonded housing a second cable/fiber  220   b . The fibers  220   a,b  may be used as a longitudinal strain gage for the coiled tubing  50  disposed in and/or being injected into a wellbore. The first fiber  220   a  may experience temperature and strain of the coiled tubing and the second fiber  220   b  may experience temperature of the coiled tubing. The second fiber  220   b  may be used to compensate the first fiber strain measurement for temperature. Using the longitudinal strain gage  220   a,b , stress along the coiled tubing may be monitored and recorded to more accurately determine fatigue life of the coiled tubing. The neutral point of the coiled tubing may be determined during drilling applications so that the coiled tubing may be kept in tension during drilling for longer life expectancy. Weight on bit may be communicated to an automated injector controller so that the controller may maintain a predetermined weight-on-bit while injecting the coiled tubing into the wellbore during a drilling operation. For example, during a directional drilling operation, the predetermined WOB may equal or exceed a first order buckling threshold but be less than or substantially less than a second order buckling threshold to prevent damage to the coiled tubing. Further, as discussed above, the controller may receive torque and pressure measurements from the BHA. The controller may also receive pressure measurements from the rig pump. With all of the data, the controller may calculate a resultant stress state along the coiled tubing  50  and optimize drilling conditions from the calculated resultant stress state. For example, the controller may prevent overload of a local portion of the coiled tubing. 
         [0043]      FIG. 3A  illustrates a twisted pair cable  320   t  bonded to the coiled tubing inner surface  50   s  using the coating  110 , according to another embodiment of the present invention. The twisted pair cable  320   t  may include two wires made from an electrically conductive metal or alloy, such as aluminum, copper, or alloys thereof, each wire jacketed with a dielectric material, such as a polymer. The wires and jackets may be helically intertwined and the jackets bonded to form the cable. The cable  320   t  may be directly bonded to the inner surface as shown or inserted into the conduit  100 . 
         [0044]    Alternatively, a single jacketed wire may be used instead of the twisted pair. In this alternative, an earth return circuit may be use to conduct data signals or electricity between the surface and the BHA. Additionally, an optical cable/fiber may be bonded to the inner surface by the coating so that the twisted pair cable may be used to transmit electricity and the optical fiber/cable may be used to transmit data. The additional optical cable/fiber may be circumferentially spaced from the twisted pair/cable and bonded directly to the inner surface or be disposed in the conduit with the cable for the conduit alternative discussed above. 
         [0045]      FIG. 3B  illustrates two circumferentially spaced jacketed wires  320   a,b  bonded to an inner surface of the coiled tubing  50  using the coating  110 , according to another embodiment of the present invention. The wires  320   a,b  may be directly bonded to the coiled tubing inner surface. Additionally, an optical fiber/cable may be bonded to the inner surface and circumferentially spaced from the wires  320   a,b.    
         [0046]      FIG. 3C  illustrates a coaxial electrical cable  320   c  bonded to an inner surface of the coiled tubing  50  using the coating  110 , according to another embodiment of the present invention. The coaxial cable may include a core, a buffer, a shield, and a jacket. The core and the shield may be made from an electrically conductive material. The buffer and the shield may be made from a dielectric. The shield may be a braid, tube, foil, or combinations thereof. 
         [0047]      FIG. 3D  illustrates a single electrical wire  320   w  bonded to an outer coating layer  310   a  by an inner coating layer  310   b , according to another embodiment of the present invention. The inner coating layer  310   b  may insulate the bare wire  320   w  from the coiled tubing inner surface  50   s  and the outer coating layer  310   b  may insulate the bare wire  320   w  from fluid conducted through the coiled tubing bore. The thickness of the outer coating layer  310   b  may be greater or substantially greater than a diameter of the wire  320   w . As discussed above, the inner  310   b  and/or outer  310   a  coating layer may be an aggregate of several layers. Additionally, a second bare wire may be circumferentially spaced from the wire  320   w . Alternatively, the bare wire may be inserted into the conduit and the outer layer  310   a  may be omitted. If the tubing  50  is made from the composite material, the outer layer  310   a  may be omitted and the bare wire  320   w  may be bonded directly to the tubing  50 . 
         [0048]      FIG. 4A  illustrates an electrically conductive layer  410   b  disposed between two insulating layers  410   a,c , according to another embodiment of the present invention. The electrically conductive layer  410   b  may be made from a composite, such as a metal/alloy (i.e., copper, aluminum, gold, platinum, or silver) filled polymer resin or carbon-filled polymer resin. The filling may be non-spherical or irregular particles or nano-particles, such as grains, fibers, or tubes. The metal or alloy may be plated on another metal or alloy (i.e. silver plated nickel) or coated on glass beads to reduce cost. The polymer resin may be filled past the percolation threshold. The insulating layers  410   a,c  may electrically isolate the conductive layer  410   b  from the coiled tubing inner surface  50   s  and fluid in the coiled tubing bore. The conductive layer  410   b  may conduct signals and/or electricity using an earth return circuit. The thickness of the conductive layer  410   b  may be selected to provide the same resistivity as standard copper wire for data and/or electrical transmission, such as 22 AWG copper wire. If the coiled tubing  50  is made from the composite material, the outer layer  410   a  may be omitted. 
         [0049]    The conductive layer  410   b  may further be used to monitor the integrity of one or both of the insulating layers  410   a,c . For example if the inner insulating layer  410   c  is compromised by fluid erosion, a short may form between the conductive layer  410   b  and fluid in the coiled tubing bore, thereby substantially altering resistance of the conductive layer. The failure may be detected and the coiled tubing  50  retrieved to the surface for repair or replacement. 
         [0050]      FIG. 4B  illustrates two electrically conductive layers  410   b,d  each disposed between two insulating layers  410   a,c,e , according to another embodiment of the present invention. The two conductive layers  410   b,d  may provide a complete circuit through the coiled tubing  50  without using earth for the return circuit. 
         [0051]      FIG. 4C  illustrates an electrically conductive layer  410   b  disposed between two insulating layers  410   a,c  and having a jacketed wire  420  bonded to an inner surface of the coiled tubing  50 , according to another embodiment of the present invention. Including the jacketed wire  420  makes dual use of the insulating layer  410   a . The insulating layer  410   a  may isolate the conductive layer  410   b  and bond the wire  420  to the inner surface. Alternatively, the jacketed wire  420  may be disposed in the conduit  100 . If the coiled tubing  50  is made from the composite material, the wire  420  may be bare. Additionally or alternatively, the optical cable/fiber may be disposed in the outer layer  410   a.    
         [0052]    The coiled tubing string  50  having any of the conductors  120 , 320 , 410   b,d ,  420  may be used to charge a battery of a downhole tool installed in the wellbore. A coupling may be connected to a distal end of the coiled tubing  50 . The coiled tubing  50  may then be injected into the wellbore until the coupling engages or is proximate to the downhole tool. The coupling may be wired or wireless (i.e., inductive coupling). Electricity may be transmitted from the surface to the downhole tool, thereby charging the battery of the downhole tool. The coiled tubing may then be retrieved to surface. Any of the conductors  120 ,  320 ,  410   b,d ,  420  may be used to power any downhole tool, such as a sensor sub, an orienter, a motor, and/or a tool actuator, such as a valve actuator. 
         [0053]    Alternatively, the coiled tubing  50  may be used as production tubing, and any of the conductors  120 , 320 , 410 , 420  may be used to transmit data and/or power between temperature and pressure sensors of a sensor sub connected to a distal end of the coiled tubing and the surface. Alternatively, the conductors  120 , 320 , 410 , 420  may be bonded to an inner surface of a production tubing string instead of a coiled tubing string. 
         [0054]    Alternatively, any of the conductors  120 , 320 , 410 , 420  may be used to heat the coiled tubing  50 , such as for melting/disassociating a paraffin or gas hydrates plug or preventing the formation thereof. 
         [0055]      FIG. 5A  is a cross section of a male coupling  500   m  installed at a first end  55  of the coiled tubing  50 , according to another embodiment of the present invention. The male coupling  500   m  may include a mandrel  501 , a pin  502 , and a diverter  503 . The mandrel  501  and the pin  502  may be made from any of the coiled tubing materials, discussed above. The diverter  503  may be made from a polymer, such as polyurethane, ploychloroprene, polyisoprene, or any elastomer. 
         [0056]    The diverter  503  may have a conical inner surface for transitioning flow from a bore of the coiled tubing to a bore  510  of the coupling  550   m . A profile  501   a  may be formed in an end of the mandrel  501  for receiving the diverter  503 . The profile  501   a  may include a shoulder and a lip. The shoulder may abut an end of the diverter and the lip may have an outer diameter slightly larger than an inner diameter of a corresponding profile of the diverter, thereby forming an interference fit and longitudinally and torsionally connecting the diverter  503  and the mandrel  501 . Additionally or alternatively, an adhesive (not shown) may be used to bond the diverter  503  to the mandrel  501 . Each of the diverter  503  and the mandrel  501  may have a hole  501   h  (only mandrel hole shown) formed therethrough for pressure equalization. A groove  503   g  may be formed in an outer surface of the diverter  503  for receiving an end of the coating  310 . A port  503   p  may be formed in a wall of the diverter  503  and in communication with the groove  503   g  for passage of one of the conductors  320 . A portion of the groove  503   g  adjacent the port may be enlarged for receiving one of the conductors  320 . 
         [0057]    An opening  501   o  may be formed in an outer surface of the profile  501   a  and a port  501   p  may be formed in a wall of the mandrel  501 . The opening  501   o  may provide for passage of one of the conductors  320  and the port  501   p  may house a booted contact  504  and high pressure feed-thru  505 . An end of the conductor  320  may be sealed within the booted contact  504  and the booted contact may provide electrical communication between the conductor  320  and the feed-thru  505  via connection with a first end of the feed-thru. A second end of the feed-thru may be in electrical communication with a lead  550  ( FIG. 5C ). A recess  501   r  may be formed in the mandrel outer surface for receiving a spring contact  551  ( FIG. 5C ). The spring contact  551  may be connected to the lead  550  and may abut a contact ring  552  ( FIG. 5C ) disposed in an inner surface of the pin  502 . The contact ring  552  may be connected to a lead  553  ( FIG. 5C ) extending through a wall of the pin  502  to a groove  502   g  formed in an outer surface of the pin. A spring ring contact  554  ( FIG. 5C ) may be disposed in the groove  502   g  for providing electrical communication between the pin  502  and a box  512  of the female coupling  500   f.    
         [0058]    The mandrel  501  may have a socket  501   s  formed in an outer surface thereof and the coiled tubing end  55  may have a dimple protruding from an inner surface thereof received by the socket, thereby longitudinally and torsionally connecting the mandrel to the coiled tubing end. The connection may be reinforced in tension by a conical outer surface  501   c  of the mandrel  501  receiving a split wedge ring  506  and abutment of the wedge ring  506  with an inner surface of the coiled tubing end  55 . The mandrel  501  may also have a threaded outer surface  501   t  engaging a threaded inner surface  502   t  of the pin  502 , thereby longitudinally and torsionally coupling the pin and the mandrel. A nut  507  may be longitudinally connected to the pin  502  by a shoulder and a fastener, such as a snap ring  511 . The nut  507  may rotate freely relative to the pin  502 . The nut  507  may have a threaded outer surface  507   t . The pin  502  may have splines  502   s  formed around an outer surface thereof and at a tip thereof. A tip of the coiled tubing end  55  and a shoulder of the pin  502  may each be beveled  55   b ,  502   b  so a smooth and flush aggregate outer surface is formed. Various interfaces of the coupling  500   m  may be sealed with seals (denoted by black filling), such as o-rings. 
         [0059]      FIG. 5B  is a cross section of a female coupling  500   f  installed at a second end  55  of the coiled tubing  50 . The male coupling  500   m  may be installed at the external end  55   i  and the female coupling may be installed at the internal end  55   o  of the coiled tubing  50  or vice versa. Alternatively, both ends  55  may include male  500   m  or female  500   f  couplings. The female coupling  500   f  may include the mandrel  501 , a box  512 , and the diverter  503 . As with the male coupling  500   m , the box  512  may be fastened to the mandrel  501  with a threaded connection. As with the pin  502 , the mandrel spring contact  557  ( FIG. 5C ) may abut a contact ring  558  ( FIG. 5C ) disposed in an inner surface of the box  512 . The contact ring  558  may be connected to a lead  556  ( FIG. 5C ) extending through a wall of the box  512  to a contact band  555  disposed on an inner surface of the box  512 . The contact band  555  may receive the pin spring ring contact  554 , thereby electrically connecting the pin  502  and the box  512 . An inner surface of the box  512  adjacent a tip of the mandrel  501  may have splines  512   s  formed therein for receiving the splined tip  502   s  of the pin  502 , thereby torsionally connecting the pin and the box. An inner surface of the box  512  proximate a tip of the box may be threaded  512   t  for receiving the nut  507 , thereby longitudinally connecting the pin  502  and the box  512 . 
         [0060]      FIG. 5C  is a cross section of a connected coupling assembly  500 . Assuming the male coupling  500   m  is connected to the coiled tubing end  55  and the female coupling  500   f  is connected to a tool (not shown), such as a BHA or injector, a conductor  560  of the tool may extend through the diverter  503  and be sealed within the booted contact  504  connected to the feed-thru  505 . A lead  559  may extend from the feed-thru  505  to the mandrel spring contact  557 , thereby providing electrical communication between the tool and the conductor  320 . 
         [0061]    Additionally, the male  500   m  and female  500   f  couplings may include a second booted contact  504 , feed-thru  505 , and leads/contacts  550 - 559  so that a second conductor (i.e., twisted pair  320   t , circumferentially spaced  320   b , or coax  320   t ) may be used. 
         [0062]      FIGS. 6A-6F  illustrate a method for splicing one of the couplings  500   f,m  to one of the coiled tubing ends  55 , according to another embodiment of the present invention. Once the conductor  320  has been bonded to the coiled tubing  50  with the coating  310 , a portion of the coating  310  may be cut and removed from the coiled tubing end  55 , thereby allowing reception of the coupling  500   f,m . A portion of the jacket may then be stripped from the conductor  320  to expose the wire  320   w . Additionally, if the conduit  100  is used, a portion of the conduit may also be stripped from the conductor  320 . The conductor  320  may then be inserted through the diverter passage  503   p . Alternatively, the jacket may be stripped after insertion through the diverter passage. The exposed wire  320   w  may then be sealed in the booted contact  504 . The booted contact  504  may then be fastened to the feed-thru  505 . The diverter  503  may then be connected to the mandrel  501 . The mandrel  501  and the diverter  503  may then be inserted into the coiled tubing end  55  until an end of the coating  310  is received into the groove  503   g . The coiled tubing end  55  may then be crimped, thereby forming the dimple  55   d  into the socket  501   s . The split wedge ring  506  may then be pressed into the coiled tubing end  55 . To protect the couplings  500   f,m  during shipment and storage and to allow handing of the coiled tubing ends  55 , a protector and lift plug/cap  605   f,m  may be fastened to each of the couplings  500   f,m , such as with a threaded connection. 
         [0063]    Once spooled on a reel of the coiled tubing unit, the coupling at the internal end  55   i  may be connected to a hydraulic or mud system and a data and/or power system using one or more swivels (not shown), such as an electrical and/or hydraulic swivel or an optical and/or hydraulic swivel. The electrical swivel may include slip rings or inductive couplings to transfer data and/or power. 
         [0064]    Additionally, either of the couplings  500   f,m  may be used to connect the coiled tubing string  50  to a second coiled tubing sting (not shown) having either or both the couplings  500   f,m  to create a longer string, such as for insertion into deep wellbores. 
         [0065]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.