Abstract:
A wellbore communication system includes a first downhole positionable cable spool and a second downhole positionable cable spool. A downhole relay receives and repeats power and/or data signals between cables of the first and second cable spools.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to communicating data and/or power in a well. 
         [0002]    Many well devices used in drilling, completing and reworking a well require power and/or communicate data with other devices in the well and on the surface. Data and/or power can be communicated over a cable into the well. However, the cable, if not maintained taught, can be subject to slacking, which may cause the cable to contact and wear on components in the well. Similarly, the cable can tangle and knot or hang-up in the well. These problems are particularly acute when the well deviates from vertical, because the cable must traverse a bend or span a horizontal portion of the well. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0003]      FIG. 1  is a schematic side cross-sectional view of a well incorporating a well string and utilizing a cable management system. 
           [0004]      FIG. 2A  is a detail side cross-sectional view of a well depicting an example spool of a cable management system.  FIG. 2B  is a detail side cross-sectional view of the cable brake of spool of  FIG. 2A . 
           [0005]      FIG. 3  is a detail side cross-sectional view of a well depicting the example spool of  FIG. 2A  received in an example interface sub of the well string. 
           [0006]      FIG. 4  is a schematic of an electronics and controller package. 
           [0007]      FIG. 5  is a detail side cross-sectional view of a well string depicting an example surface communication sub. 
       
    
    
       [0008]    Like reference symbols in the various drawings indicate like elements. 
       DETAILED DESCRIPTION 
       [0009]    An example of a cable management system constructed in accordance with the concepts described herein incorporates one or more spools that pay out cable from one location, within or outside of a well, to another location within a well in a controlled fashion. In doing so, the cable management system facilitates using cable to communicate data and/or power with well devices downhole. For example, the one or more spools can be utilized to pay out cable to devices in a well string as the string is extended into the well. Unlike a traditional wireline system, the cable does not support the devices in the well. In certain instances, one or more of the spools can be docked in a tubular, such as the well string, to be attached to move with the tubular. A segment of cable can be paid out from one spool while data and/or power is communicated to a downhole device over the cable. The spool can be docked and the segment of cable communicably coupled to a segment of cable of a second spool. Thereafter, the second spool can be used to pay out cable to the first spool while data and/or power is communicated over the cable. If needed, the second spool can be docked, and a third spool used to pay out cable to the second while data and/or power is communicated over the cable, and so on. The spools include an interface sub to condition and/or amplify the data, and in certain instances, add data from additional sources to the data being transmitted. The cable management system enables use of multiple shorter segments of cable to span a distance, rather than a single long segment of cable spanning the entire distance. In certain instances, the multiple shorter spans help prevent or eliminate problems such as excess slacking and tangling of the cable. 
         [0010]    Referring first to  FIG. 1 , an example cable management system  10  is shown in a drilling context, incorporated into a tubular well string  12 . In  FIG. 1 , the well string  12  is depicted as a drill string used to drill a wellbore  14  of a well. The concepts discussed herein, however, are not limited to use in drilling or with drill string, however, and could be used in connection with other types of well strings and well operations, including well treatment (e.g., fracturing, gravel packing, acidizing and/or other treatments via a well treatment string), production (via a production string), workover (via a work string) and/or other types of operations. 
         [0011]    The well string  12  extends downhole into the wellbore  14  from a drilling rig  18  at a terranean surface  20 . The well string  12  is constructed of multiple joints of tubing and other components. In particular, because it is a drill string, the well string  12  depicted in  FIG. 1  has a drill bit  24  coupled to a drilling motor (e.g., a mud motor, electric motor and/or other type of motor) to drive the drill bit  24  in drilling through the Earth. The well string  12  is lengthened to allow it to extend deeper into the Earth by adding additional joints of tubing and/or other components. The tubing and/or other components are added to the well string  12  at the drilling rig  18 , and can be coupled together at a box and pin threaded connection. In other instances, the well string  12  can be partially or wholly constructed of coiled tubing that, rather than being made up of multiple lengths of relatively short tubing (typically 31 ft/9.6 m), is a single continuous length. The coiled tubing is uncoiled from a spool at the surface  20  as it is extended deeper into the Earth. 
         [0012]    The cable management system  10  manages a cable  16  that runs through the center bore of the well string  12 . The cable  16  extends from a location proximate the surface  20  to one or more devices in the wellbore  14  (hereinafter the “communicated devices”) and communicates power and/or data between the communicated devices and the location proximate the surface  20 . Target sub  22 , carried in the well string  12 , is an example communicated device with which the cable  16  communicates power and/or data. In certain instances, as will be discussed in more detail below, the cable  16  additionally or alternatively communicates power and/or data with one or more other communicated devices in the well string  12  and/or wellbore  14 . 
         [0013]    The data can be in the form of communications to and/or from the devices. Some examples of communications can include control communications (e.g., a signal to actuate or otherwise affect the operation of a device), information about the status of a device, data output from a device (e.g., data and signals output from a sensor), and/or other types of communications. The power can be used to power the communicated device and/or other elements in the well. In certain instances, data and power can be communicated concurrently. Some examples of the communicated devices include devices that collect data about the well string  12 , the fluids within the bore of well string  12 , the fluids outside of the well string  12  (including those in the annulus between the well string  12  and the wall of the wellbore  14 , as well as those in the surrounding formations), formation evaluation sensors, drilling mechanics sensors, surveying sensors, accelerometers, magnetometers, pressure sensors, temperature sensors, and/or other devices. The communicated devices can include devices controlled by the communications including valves and ports (e.g., actuable to open/close and/or otherwise adjust), seals (e.g., actuable to seal/not seal), actuable well string  12  centralizing or stabilizing mechanisms (e.g., actuable to extend/retract from the well string  12 ) and/or other devices. 
         [0014]    In certain instances, the target sub  22  includes measurement-while-drilling (MWD) communicated devices such as one or more sensors for sensing conditions in the wellbore  14  (e.g., pressure, temperature and/or other conditions), one or more accelerometers for determining the trajectory of the well string  12 , one or more magnetometers for determining the orientation of the well string  12  relative to the Earth&#39;s magnetic field and/or other devices. The MWD devices can be controlled via the cable  16 , and data can be communicated, for example between the MWD devices and the surface  20  and/or another location, via the cable  16 . In certain instances, the target sub  22  may alternatively or additionally include logging-while-drilling (LWD) communicated devices such as one or more sensors for sensing conditions of the formation (e.g., resistivity, porosity, sonic velocity, density via gamma ray and/or others) and/or other devices. The LWD devices can be controlled via the cable  16 , and data can be communicated, for example between the LWD devices and the surface  20  and/or another location, via the cable  16 . 
         [0015]    The cable  16  can be an electric conductor or wire, fiber optic or other type of cable for communicating data and/or power. The cable  16  can include one or more wires and/or optical fibers housed in a protective sheath, and can define one or multiple parallel communication paths. The wires and/or optical fibers can be arranged in one or multiple configurations, including twisted-pair, coaxial, and/or other arrangements. The wires and/or optical fibers can be insulated or uninsulated within the sheath. The optical fibers can include single and/or multi-mode optical fibers. In certain instances, single mode optical fibers can be used over multi-mode optical fibers to provide a reduced diameter cable  16 . The protective sheath, in certain instances, can be of a high tensile strength to provide the primary tensile strength of the cable  16 . In certain instances, the protective sheath is a high-strength toughed fluoropolymer (HSTF) and/or other material. 
         [0016]    The ends of the cable  16  and/or segments of the cable terminate in connectors adapted to attach and be retained to other components (e.g., by mating detent and slot and/or otherwise). The cable ends may be designed to prevent stress accumulation between the connector and the filaments of the cable  16 , for example, by tapering the transition between the connector and connector, including an armor extending from the connector a specified length along the filaments of the cable  16 , and/or otherwise. In instances where the cable  16  includes optical fibers, the connector may include an optical/electrical interface, for example a photo diode, photo transistor and/or otherwise be connected to electrical contacts of the connector. In certain instances, the connector can include other components such as, signal conditioning electronics, power supply (e.g., battery), and/or other functions. 
         [0017]    The cable management system  10  includes one or more bobbins or spools  30  (three shown) on which the cable  16  is carried. The spools  30  are used to carry the cable  16  into the wellbore  14 , and maintain the cable  16  in an organized fashion while the cable  16  is paid out to the target sub  22  and to other spools  30  as the well string  12  moves downhole through the wellbore  14 . In certain instances, one segment of cable  16  is wound on one spool  30 ; however, in other instances, multiple segments can be wound on a single spool  30  to be paid out in parallel or sequentially. 
         [0018]    When the system is fully deployed, a segment of the cable  16  spans between the target sub  22  and the downhole -most spool  30  and, if using multiple spools  30  as in  FIG. 1 , additional segments span between the intermediate and uphole most spools  30 . An end of cable  16  is communicably coupled to the target sub  22  to communicate power and/or data with the devices thereof, and is also mechanically attached, directly or indirectly, to the target sub  22  such that as the target sub  22  is moved away from the spool  30  (or the spool  30  moved away from the target sub  22 ) the cable  16  is drawn off the spool  30 . The spools  30  can be adapted to maintain tension on the cable  16  as it is paid out, for example, to prevent the cable  16  from prematurely uncoiling from the spool  30 . The number of spools  30  used can depend on a number of factors, including the distance to be spanned by the cable  16 , the desired length of the cable segments carried on the spools  30 , the desired length of the spans between the spools  30  and between the downhole most spool  30  and the target sub  22 , and/or other factors. In certain instances, the spacing requirements of sensors in the string  12  (including sensors in the interface sub  32 , discussed below) and/or sensors in the spools  30  (also discussed below) can influence the distance spanned by the cable  16 . Using a greater number of spools  30  over a given distance facilitates shorter segments of cable  16  between the spools  30  than if fewer spools  30  are used. In certain instances, shorter segments of cable  16  are less prone to slacking and tangling. In certain instances, it is desirable to use a greater number of spools for spanning longer distances than shorter distances. Of note, although described and shown with the cable  16  being paid off from the spools  30  toward the downhole direction, the system could be arranged oppositely with one or more spools  30  paying off cable  16  toward the uphole direction. 
         [0019]    The spools  30  can be adapted to interface communications of data and/or power with the segment of cable  16  carried thereon. In certain instances, the spools  30  can be adapted to interface communications of data and/or power from one segment of cable  16  to another to enable use of multiple segments of cable  16  to span between the target sub  22  and the location proximate the surface  20 . For example, a spool  30  carrying a segment of cable  16  can interface with, and communicate power and/or data, with a segment of cable  16  carried on another spool  30 . In  FIG. 1 , the downhole most spool  30  communicates power and/or data with its segment of cable  16  and with the segment of cable  16  carried by the intermediate spool  30 . The intermediate spool  30  communicates power and/or data with its segment of cable  16  and the segment of cable  16  carried by the uphole most spool  30 . In certain instances, one or more of the spools  30  can include one or more communicated devices with which the cable  16  communicates power and/or data, such as the communicated devices described above. 
         [0020]    The spools  30  can include a gripping mechanism  34  (e.g., a collet, dog, slips and/or other gripping mechanism) configured to grip the inside of tubing, such as the inside of well string  12 , and support the spool  30  relative to the tubing. When gripped to the tubing, the spool  30  is carried to move with the tubing. The gripping mechanism  34  can be biased to allow the spool  30  to move uphole relative to the tubing, and to grip and support the spool  30  against movement, relative to the tubing, downhole. In certain instances, the gripping mechanism  34  can be automated (e.g., by motor, hydraulics, and/or otherwise) to crawl through the inside of tubing, such that the spool  30  can be actuated to crawl uphole or downhole through tubing to maintain the spool  30  depth as the tubing is extended deeper into the well. The gripping mechanism  34  can be actuated to crawl through the tubing in one or a number of different manners, including via radio frequency communication, acoustic communication, infrared (IR) communication, wired communication, optical communication (e.g., fiber optic and/or other), communication over an inductive coupling, pressure signal and/or other mode of communication. In certain instances, the gripping mechanism  34  can be actuated to crawl via communications over cable  16 .  FIG. 2 , discussed below, shows an example spool  300  that can be used as spool  30 . 
         [0021]    In certain instances, the cable management system  10  can include one or more interface subs  32  (two shown). The interface sub  32  is configured to receive a spool  30  to dock therein, and when docked, be carried with the spool  30  to move with spool  30 . The interface sub  32  can interface with the gripping mechanism  34  of the spool  30 , for example having an internal profile that engages the gripping mechanism  34  to facilitate docking the spool  30 . 
         [0022]    In certain instances, one or more of the interface subs  32  can include one or more communicated devices with which the cable  16  communicates power and/or data, such as those described above. One or more of the interface subs  32  can include additional functions, including a repeater that is configured to repeat and, in certain instances, condition (e.g., reformat, remove noise, amplify and/or other conditioning) the data communicated by the cable  16 . For example, data and/or power communicated on a segment of cable  16  of a spool  30  docked in an interface sub  32  is communicated with the interface sub  32 , then repeated and/or conditioned and output to the next segment of cable  16  coupled to the spool  30  via a connector. The interface sub  32  can include a power supply (e.g., battery) for supplying power to the repeating and/or conditioning circuits, for supplying power to the spool  30 , for supplying power communicated devices and/or other devices of the interface sub  32 , and/or for supplying power to another component of the well string  12  apart from the interface sub. In certain instances, the interface sub  32  can communicate power and/or data with the segment of the cable  16 , for example, via the spool  30  docked therein.  FIG. 3  shows an example interface sub  320  that can be used as interface sub  32 . 
         [0023]    The uphole most spool  30  can communicate outside of the well string  12 , for example with external device  36  outside of the well string  12  at the surface  20 , via an additional segment of cable  16 , a wireless link, and/or in another manner. In certain instances, the well string  12  can be provided with a surface communication sub  60  installed at or near the top of the well string  12  to facilitate this communication. In certain instances, it may be desirable to configure the surface communication sub  60  as a saver sub, i.e., a tubing adapted to couple between the top drive of rig  18  and the remainder of the well string  12 , and below which tubing and components are added to the well string  12  to save wear and tear on the coupling of the top drive. The surface communication sub  60  can include a communications coupling for communicating with the uphole most spool  30 , and a transmitter/receiver for communicating with the external device  36 , such that communications are relayed between the external device  36  and the uphole most spool  30 . In certain instances, the coupling can communicate with the uphole most spool  30  wirelessly (e.g., via radio frequency (RF), infrared (IR), acoustic, inductive, magnetic and/or otherwise). In certain instances, the transmitter/receiver can communicate with the external device  36  (e.g., via radio frequency (RF), infrared (IR), acoustic, inductive and/or otherwise). The external device  36  can be one or a number of different devices. Some examples of external devices  36  can include a control panel for a human operator, a data storage device, a controller and/or other devices.  FIG. 5 , discussed below, shows an example surface communication sub  600  that can be used as surface communication sub  60 . 
         [0024]    As mentioned above,  FIG. 2A  shows an example spool  300  that can be used as spool  30 . The spool  300  includes a tubular outer drum  302  mounted on a tubular inner drum  304 . A segment of the cable  16  is coiled around the outer drum  302  and extends through an aperture  310  ( FIG. 2B ) in the lower end of the inner drum  304 . The aperture  310  is positioned and/or oriented to prevent the cable  16  from exceeding its critical bending radius, beyond which the cable  16  will be damaged or break, as the cable is paid off the spool  300 . The outer drum  302  is biased toward and traps the cable  16  against a brake material  306  at the downhole end of the inner drum  304  by a helical spring  308 . In the configuration shown, the brake material  306  is annular having a female conical surface that abuts a corresponding male conical surface of the drum  302 . In certain instances, the brake material  306  can be a carboxilated nitrile. The cable  16  trapped between the outer drum  302  and the brake material  306  provides a small amount of resistance to maintain the cable  16  from prematurely unwinding from the outer drum  302 . As tension is applied to the cable  16  from downhole of the spool  300 , the cable  16  draws the outer drum  302  into stronger engagement with the brake material  306 . This stronger engagement, in turn, traps the cable  16  more strongly between the outer drum  302  and brake material  306  and provides an increased amount of resistance to paying out the cable  16  from the spool  300 . In certain instances, the resistance limits the rate at which the cable  16  is paid off the spool  300  and prevents the cable  16  from being deployed too rapidly. 
         [0025]    The helical spring  308 , affixed both to the outer drum  302  and inner drum  304 , also limits the amount in which the outer drum  302  can rotate relative to the inner drum  304 . As the helical spring  308  coils tighter, it generates a torque that counters the torque applied by the cable  16  as it pays off the bottom of the outer drum  302 . The counter torque generated by the helical spring  308  tends to maintain the cable  16  in tension as the tension in the cable  16  itself changes (e.g., from flexure of the cable  16  and movement of the string). 
         [0026]    The upper end of the inner drum  304  includes a housing  312  with a female receptacle for communicably coupling and attaching to the male connector of the cable  16 . In other instances, the cable  16  can have a connector with a female receptacle and the housing  312  a male connector. The housing  312  includes electronics for interfacing the communication of power and/or data from one segment of the cable  16  to the segment of the cable  16  carried on the spool  300 . The upper end of the outer drum  302  includes a notch through which the cable  16  passes and couples to the housing  312  of the inner drum  304 .  FIG. 2A  also shows radially extendable/retractable dogs  314  (e.g. extendable/retractable by motor, spring, hydraulically and/or otherwise), adapted to engage the interior of tubing (e.g., well string  12 ) and support the spool  300  relative to the tubing. The dogs  314  are arranged around the circumference of the housing  312 . Three equally spaced dogs  314  are shown, however, fewer or more can be provided. The dogs  314  of  FIG. 2A  are configured to engage the interior of tubing to prevent the spool  300  from moving downhole relative to the tubing. The dogs  314  can be of a type that engage and grips a profile in the well string and/or can be of a type that engage and grips the well string apart from a profile (e.g., slips and/or the like). 
         [0027]      FIG. 2A  also shows a lifting tool  316  for carrying the spool  300  up through the bore of a well string (e.g., well string  12 ). The tool  316  has an articulating assembly  318  that folds upon entering the central bore of the spool  300 . Upon emerging from the downhole end of the spool  300 , the assembly  318  opens automatically (e.g., by motor, spring and/or otherwise) or manually (e.g., by manually operated linkage and/or otherwise), engaging the downhole end of the spool  300 . When opened, the tool  316  can lift the spool  300  via a long handle  322  attached to the articulated assembly  318 . 
         [0028]      FIG. 3  shows an example interface sub  320  that can be used as interface sub  32 . The interface sub  320  is shown coupled to a spool  300 . The interface sub  320  includes a tubing  324  adapted to couple into the well string  12  (e.g., threadingly and/or otherwise). The interior of the tubing  324  is sized to and may also include a profile to engage with the gripping mechanism (e.g., dogs  314 ) of the spool (e.g., spool  30 ,  300 ) to enable the spool to be docked in and carried in the interface sub  320 . The interface sub  320  includes a battery  326  coupled to an electronics module  328 . The interface sub  320  also includes a communications coupling  332  (e.g., wired and/or wireless) for communicating data and/or power with components of the spool  300 , such that the interface sub  320  can communicate with the cable  16  via the spool  300 . The communications coupling  332  is coupled to the electronics module  328  and the battery  326 . The electronics module  328  can include a repeater that is configured to condition (e.g., reformat, remove noise, amplify and/or other conditioning) the communications from the cable  16 . The electronics module  328 , in certain instances, can be configured to apply power from the battery  326  to amplify the communications from the cable  16 . In certain instances, the interface sub  320  can include one or more communicated devices  334  (shown as a transducer), such as those described above, with which the cable  16  communicates data and/or power. Data and/or power can be communicated with the communicated devices  334  to the surface and/or to other devices downhole. 
         [0029]      FIG. 4  shows an example electronics and controller package  402  that can be provided in the spools  300 . The electronics and controller package  402  can be provided with a battery  404  coupled to the package  402 . The package  402  is configured to communicate (e.g., wired and/or wirelessly) with the cable carried on the spool and with another cable coupled to the spool. The electronics and controller package  402  can include a repeater that is configured to condition (e.g., reformat, remove noise, amplify and/or other conditioning) the communications from the cable  16 . The package  402 , in certain instances, can be configured to apply power from the battery  404  to amplify the communications from the cable  16 . In certain instances, the electronics and controller package  402  can include one or more communicated devices  408  (shown as transducers), such as those described above, with which the cable  16  communicates data and/or power. Data and/or power can be communicated with the communicated devices  408  to the surface and/or to other devices downhole. 
         [0030]      FIG. 5  shows an example surface communication sub  600  that can be used as surface communication sub  60 . The surface communication sub  600  includes a tubing  602  adapted to couple into the well string  12  (e.g., threadingly and/or otherwise), and in certain instances to couple between a top drive of the rig  18  ( FIG. 1 ) and the remainder of the well string  12 . In certain instances, the surface communication sub  600  is configured as a saver sub. The surface communication sub  600  includes a battery  604  coupled to power a wireless transmitter/receiver  608  (e.g., radio frequency (RF), infrared (IR), acoustic, inductive and/or other transmitter/receiver) and its associated electronics  606 . As shown in  FIG. 5 , the battery  604 , transmitter/receiver  608  and associated electronics  606  are mounted in a recess in the outer wall of the tubing  602 , such that the outside diameter of the surface communication sub  600  is substantially uniform. The transmitter/receiver  608  and its associated electronics  606  enable communication with a device external to the well string, such as external device  36  ( FIG. 1 ). 
         [0031]    The surface communication sub  600  includes a coupler tube  610  carried in the central bore of the tubing  602  and in communication with the battery  604 , transmitter/receiver  608  an associated electronics  606  via a flexible cable  612 . A bearing  614 , biased radially outward for example by a spring and/or otherwise, is provided on the coupler tube  610  to centralize the coupler tube  610  in the bore of the tubing  602 . The surface communication sub  600  includes one or more motor driven pinions  616  that engage the exterior of the coupler tube  610  (e.g., by engaging a rack  618  or other structure on the exterior of the coupler tube  610 ) and can be actuated to drive the coupler tubing  610  up and down along the longitudinal axis of the surface communication sub  600 . 
         [0032]    The coupler tube  610  includes an inductive communications coupling  620  about its lower (downhole) end for communicating data and/or power with a corresponding inductive coupling of a spool (e.g., spool  30 ,  FIG. 1 ) and/or an interface sub (e.g., interface sub  32 ,  FIG. 1 ). The communications coupling  620  in turn communicates via the flexible cable  612  with the battery  604 , transmitter/receiver  608  and associated electronics  606 . The inductive coupling  620  can be moved into and out of proximity with the spool, to inductively communicate or break communication, by actuating the motor driven pinions  616 . Communications to and from the spool via the communications coupling  620  are relayed to the external device (e.g., external device  36  of  FIG. 1 ) via the transmitter/receiver  608 . Power from the battery  604  and/or another source is communicated to the spool via the communications coupling  620 . 
         [0033]    Referring back to  FIG. 1 , in operation, a segment of cable  13  is coupled to a device, for example target sub  22 , in the well string  12  and a spool  30  carrying the segment of cable  13  is supported in the bore of the well string  12 . The gripping mechanism  34  can be used to support the spool in the well string  12 . Communication of power and/or data is established with the spool  30 , and communicated between the spool  30  and the device (e.g., target sub  22 ) via the cable  16 . In certain instances, the spool  30  can communicate with an external device  36  at the terranean surface  20 . In instances using a communications sub  60 , the communications sub  60  is operated to communicate between the spool  30  and the external device  36 . 
         [0034]    As the well string  12  is extended deeper into the Earth (e.g., as the as the drill bit  24  drills deeper into the Earth), it is lengthened by adding joints of drill pipe and/or other components at the rig  18 . The spool  30  travels deeper into the Earth with the string  12  and is periodically and/or continually raised to maintain the spool  30  proximate the surface  20 , and if provided, proximate and in communication with the surface communication sub  60 . The spool  30  can be raised using a lifting tool (e.g. lifting tool  316 ), or if the spool  30  is so configured, the spool  30  can be actuated to crawl uphole through the string  12  to maintain its position. As the spool  30  is raised, the segment of cable  16  carried by the spool  30  is paid off the spool  30  toward the device in a controlled manner. The spool  30  maintains tension on the cable preventing too much cable from being spooled off and reducing the likelihood of slacking and tangling. Communication of power and/or data is maintained with the spool  30 , and in turn, is communicated from the spool  30  to the device via the cable  16 . 
         [0035]    As the segment of cable  16  carried by the spool  30  begins to run out or at another specified location in the well string  12 , an interface sub  32  can be provided in the well string  12  for the spool  30  to dock into. Thereafter, a second spool  30  is supported in the well string  12  and its second cable  16  is coupled to the first spool  30 . Communication of power and/or data is established between the first and second spools  30  via the second cable  16 . The second spool  30  can communicate with the external device  36  at the terranean surface  20 , for example, using the surface communications sub  60 . 
         [0036]    The power and/or data communicated between the terranean surface  20 , the first and second spool  30 , and the target sub  22  can be repeated and, in certain instances, conditioned (e.g., reformat, remove noise, amplify and/or other conditioning) by the spools  30  and/or interface subs  32 . 
         [0037]    As the first and second spools  30  travel deeper into the Earth with the string  12 , the second spool  30  is periodically and/or continually raised to maintain the spool  30  proximate the surface  20 . As the segment of second cable  16  carried by the second spool  30  begins to run out or at another specified location in the well string  12 , a second interface sub  32  can be provided in the well string  12  for the second spool  30  to dock into. Thereafter, a third and subsequent spools  30  can be supported in the well string  12  and coupled to preceding spools  30  in the same manner as needed. 
         [0038]    A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made. Accordingly, other embodiments are within the scope of the following claims.