Patent Publication Number: US-10760349-B2

Title: Method of forming a wired pipe transmission line

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 13/904,297 filed May 29, 2013, the disclosure of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     During subterranean drilling and completion operations, a pipe or other conduit is lowered into a borehole in an earth formation during or after drilling operations. Such pipes are generally configured as multiple pipe segments to form a “string”, such as a drill string or production string. As the string is lowered into the borehole, additional pipe segments are coupled to the string by various coupling mechanisms, such as threaded couplings. 
     Pipe segments can be connected with tool joints that include a threaded male-female configuration often referred to as a pin-box connection. The pin-box connection includes a male member, i.e., a “pin end” that includes an exterior threaded portion, and a female member, i.e., a “box end”, that includes an interior threaded portion and is configured to receive the pin end in a threaded connection 
     Various power and/or communication signals may be transmitted through the pipe segments via a “wired pipe” configuration. Such configurations include electrical, optical or other conductors extending along the length of selected pipe segments. The conductors are operably connected between pipe segments by a variety of coupling configurations. 
     Some wired pipe configurations include a transmission device mounted on the tip of the pin end as well as in the box end. The transmission device, or “coupler,” can transmit power, data or both to an adjacent coupler. The coupler in the pin end might be connected via a transmission line to the coupler in the box end. 
     BRIEF DESCRIPTION 
     Disclosed herein is wired pipe system that includes a wired pipe segment having a first end and a second end; a first coupler in the first end and a second coupler in the second end; and a transmission line disposed in the wired pipe segment between the first and second ends. The transmission line includes a transmission cable that includes an inner conductor and an insulating material disposed about the inner conductor. The transmission line also includes a wire channel surrounding the insulating material and the inner conductor for at least a portion of a length of the transmission cable. The wire channel and the insulating material are mated by means of at least one mating feature. 
     Also disclosed herein is a method of forming a wired pipe transmission line comprising: providing an assembly that includes insulating material disposed about an inner conductor; surrounding the insulating material with a shield layer to form a transmission cable; forming mating features in the shield layer; disposing the transmission cable within a wire channel; disposing a fixation element between the shield layer and the wire channel; and fixedly attaching the fixation element to the wire channel. 
     Further disclosed is a wired pipe transmission line for transmitting electrical signals in a wired pipe system, the wired pipe transmission line includes a transmission cable including: an inner conductor; an insulating material disposed about the inner conductor; and a shield layer surrounding the insulating material having shield layer mating features disposed on an outer surface thereof. The transmission line also includes a wire channel surrounding the insulating material and the inner conductor for at least a portion of a length of the transmission cable and a fixation element disposed between the shield layer and the wire channel that is fixedly attached to the wire channel, the fixation element including fixation element mating features formed on an inner portion that mate with shield layer mating features. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  depicts an exemplary embodiment of a wired pipe segment of a well drilling and/or logging system; 
         FIG. 2  depicts an exemplary embodiment of a box end of the segment of  FIG. 1 ; 
         FIG. 3  depicts an exemplary embodiment of a pin end of the segment of  FIG. 1 ; 
         FIG. 4  shows a perspective view of a transmission cable according to one embodiment; 
         FIG. 5  shows a cut-away side view of the transmission cable of  FIG. 4 ; 
         FIG. 6  shows a perspective view of a transmission cable according to another embodiment; 
         FIGS. 7 a  and 7 b    show perspective views of portions of a transmission cable according to another embodiment; and 
         FIG. 8  shows a cut-away side view of a transmission cable according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed system, apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     As described above, the couplers in a wired pipe system are electrically connected via a transmission cable. Embodiments herein are directed to transmission cable that can be used in a wired pipe system and examples of how such transmissions cables may be formed. In one or more of the embodiments disclosed herein, the transmission cable is capable of withstanding one or more loads, as tension, compression and torsion and superimposed dynamic accelerations typically present in downhole tools during drilling. In one embodiment, the transmission line consists of a wire channel and a transmission cable (one of coaxial cable, twisted pair wires, individual wires, for example) enclosed in the wire channel. While various manners of producing the wire channel are disclosed herein, any or all of them are formed such that the transmission cable can be held in a fixed position relative to the wire channel. In one embodiment, a fixation element interfaces with the transmission cable and is welded into fixed contact with the wire channel. In another embodiment, rather than a weld, the fixation element may be glued or otherwise affixed (e.g., by the use of microspheres) to the wire channel. In yet another embodiment, the fixation element can be omitted and the transmission cable itself is fixedly attached to the wire channel by any of adhesive or microsphere methods disclosed herein. 
     Referring to  FIG. 1 , an exemplary embodiment of a portion of a well drilling, logging and/or production system  10  includes a conduit or string  12 , such as a drillstring or production string, that is configured to be disposed in a borehole for performing operations such as drilling the borehole, making measurements of properties of the borehole and/or the surrounding formation downhole, or facilitating gas or liquid production. 
     For example, during drilling operations, drilling fluid or drilling “mud” is introduced into the string  12  from a source such as a mud tank or “pit” and is circulated under pressure through the string  12 , for example via one or more mud pumps. The drilling fluid passes into the string  12  and is discharged at the bottom of the borehole through an opening in a drill bit located at the downhole end of the string  12 . The drilling fluid circulates uphole between the string  12  and the borehole wall and is discharged into the mud tank or other location. 
     The string  12  may include at least one wired pipe segment  14  having an uphole end  18  and a downhole end  16 . As described herein, “uphole” refers to a location near the point where the drilling started relative to a reference location when the segment  14  is disposed in a borehole, and “downhole” refers to a location away from the point where the drilling started along the borehole relative to the reference location. It shall be understood that the uphole end  18  could be below the downhole end  16  without departing from the scope of the disclosure herein. 
     At least an inner bore or other conduit  20  extends along the length of each segment  14  to allow drilling mud or other fluids to flow there through. At least one transmission line  22  is located within the wired segment  14  to provide protection for electrical, optical or other conductors which can be part of the transmission line to be disposed along the wired segment  14 . In one embodiment, the transmission line  22  includes a coaxial cable. In another embodiment, the transmission line  22  includes any manner of carrying power or data, including, for example, a twisted pair. In the case where the transmission line  22  includes a coaxial cable it may include an inner conductor surrounded by a dielectric material. The coaxial cable may also include a shield layer that surrounds the dielectric. The transmission line  22 , as described further below, may include a wire channel that may be formed, for example, by a rigid or semi-rigid tube of a conductive or non-conductive material 
     The segment  14  includes a downhole connection  24  and an uphole connection  26 . The segment  14  is configured so that the uphole connection  26  is positioned at an uphole location relative to the downhole connection  24 . The downhole connection  24  includes a male connection portion  28  having an exterior threaded section, and is referred to herein as a “pin end”  24 . The uphole connection  26  includes a female connection portion  30  having an interior threaded section, and is referred to herein as a “box end”  26 . 
     The pin end  24  and the box end  26  are configured so that the pin end  24  of one wired pipe segment  14  can be disposed within the box end  26  of another wired pipe segment  14  to affect a fixed connection there between to connect the segment  14  with another adjacent segment  14  or other downhole component. It shall be understood that a wired pipe segment may consist of several (e.g. three) segments. In one embodiment, the exterior of the male coupling portion  28  and the interior of the female coupling portion  30  are tapered. Although the pin end  24  and the box end  26  are described as having threaded portions, the pin end  24  and the box end  26  may be configured to be connected using any suitable mechanism, such as bolts or screws or an interference fit. 
     In one embodiment, the system  10  is operably connected to a downhole or surface processing unit which may act to control various components of the system  10 , such as drilling, logging and production components or subs. Other components include machinery to raise or lower segments  14  and operably couple segments  14 , and transmission devices. The downhole or surface processing unit may also collect and process data generated or transmitted by the system  10  during drilling, production or other operations. 
     As described herein, “drillstring” or “string” refers to any structure or carrier suitable for lowering a tool through a borehole or connecting a drill bit to the surface, and is not limited to the structure and configuration described herein. For example, a string could be configured as a drillstring, hydrocarbon production string or formation evaluation string. The term “carrier” as used herein means any device, device component, combination of devices, media and/or member that may be used to convey, house, support or otherwise facilitate the use of another device, device component, combination of devices, media and/or member. Exemplary non-limiting carriers include drill strings of the coiled tube type, of the jointed pipe type and any combination or portion thereof. Other carrier examples include casing pipes, wirelines, wireline sondes, slickline sondes, drop shots, downhole subs, BHA&#39;s (Bottom Hole Assembly) and drill strings. 
     Referring to  FIGS. 2 and 3 , the segment  14  includes at least one transmission device  34  (also referred to as a “coupler” herein) disposed therein and located at the pin end  24  and/or the box end  26 . The transmission device  34  is configured to provide communication of at least one of data and power between adjacent segments  14  when the pin end  24  and the box end  26  are engaged. The transmission device  34  may be of any suitable type, such as an inductive coil, capacitive or direct electrical contacts, resonant coupler, or an optical connection ring. The coupler may be disposed at the inner or outer shoulder or in between. It shall be understood that the transmission device  34  could also be included in a repeater element disposed between adjacent segments  14  (e.g., within the box end). In such a case, the data/power is transmitted from the transmission device  34  in one segment  14 , into the repeater. The signal may then be passed “as is,” amplified, and/or modified in the repeater and provided to the adjacent segment  14 . 
     Regardless of the configuration, it shall be understood that each transmission device  34  can be connected to one or more transmission lines  22 . Embodiments disclosed herein are directed to how such transmission lines  22  can be formed. In particular, disclosed herein are transmissions lines that are formed such that including a transmission cable protected within a wire channel in a fixed manner. 
     Turning now to  FIG. 4 , an example of a transmission line  22  that includes a transmission cable  102  disposed within a wire channel. The wire channel  100  can be formed of steel or a steel alloy in one embodiment. Of course, other materials could be used to form the wire channel  100 . The wire channel  100  can be electrically coupled to or electrically isolated from the transmission line  102 . 
     The transmission cable  102  illustrated in the  FIG. 4  is a coaxial cable. Of course, other types of wires/cable could form the transmission cable  102 . For example, the transmission cable  102  could be formed as a twisted pair. 
     In the illustrated embodiment, the transmission cable  102  is shown as a coaxial cable that includes an inner conductor  201  surrounded by an insulating layer such as dielectric layer  202 . It should be understood that the wire inner conductor  201  could be a twisted pair or an individual wire that is surrounded by an insulating layer. 
     The inner conductor  201  may be formed of a solid or braided metallic wire. The insulating layer, for example dielectric layer  202 , surrounds the inner conductor  201  for most of the length of the inner conductor  201 . The illustrated transmission cable  102  can include a shield layer  204  that surrounds the dielectric layer  202 . The shield layer  204  can be formed of a highly conductive material such as copper in one embodiment and can be a braided or solid layer of material. 
     In one embodiment, the shield layer  204  may be in direct contact with the wire channel  100 . In the illustrated embodiment, the shield layer  203  may be physically separated from the wire channel  100  by, for example, an insulating layer. Of course, in such a configuration, the wire channel  100  and the shield layer  203  may be electrically coupled to one another by other means. 
     The combination of the dielectric layer  202  and the inner conductor  201  can be formed in any known manner. In one embodiment, the combination is formed such that the dielectric layer  202  and the inner conductor  201  are tightly bound. 
     In the illustrated embodiment shown in  FIG. 4-6 , the shield layer  204  includes form closures  205  that mate with form closures that may be formed in the outer surface of the insulating layer  202 . The threads  205  are on both the inner and outer sides of the shield layer  204  in the illustrated embodiment. 
     The form closures  205  on the outer side of the insulating layer  202  mate with form closures on an inner diameter of a fixation element  206 . The illustrated fixation element  206  is shown as being formed of two half shells  206   a ,  206   b  but it shall be understood that these two half shells could be replaced by a tubular member including internal threads. In the above examples, it has been assumed that the fixation element  206  is in direct contact with the shield layer  204 . 
     The fixation element  206  may only extend along the transmission line  22  at or near the ends of the transmission line  22  as is best shown in  FIG. 8 . The wire channel  100  is shown physically coupled to the fixation elements  206 . The fixation elements  206  do not extend along the entire length of the transmission line  22  but only at or near the ends thereof. The fixation elements  206  can be either the threaded elements as described above but could be replaced, for example, by an adhesive or a fluid that includes expandable microspheres. Regardless of how formed, in one embodiment, a space  220  exists between fixation elements  206  disposed at either end of the transmission line  22 . In one embodiment, the space  220  is filled with air. The space  220 , or portions thereof, could be filled by any type of element that keeps the transmission line from contacting the wire channel  100  and may include an adhesive in one embodiment. 
     Referring now again to  FIGS. 4-6 , a method of forming a transmission cable  102  is described. A transmission cable  102  is provided that includes an inner conductor  201  surrounded by insulating layer  202 . The insulating layer  202  includes, in one embodiment, threads  203  formed on an outer diameter thereof. In this illustrated embodiment, the shield layer  204  includes threads  205  that mate with the threads  203  of the insulating layer  202 . In one embodiment, the threads  203  are formed and then the shield layer  204  is added in a manner such that threads  205  are formed that match threads  203 . In another embodiment, the shield layer  204  is added to an insulating layer  202  that has a smooth outer surface and threads  203 / 205  are then impressed on the shield  204  and insulating layers  202 . It shall be understood that the threads in the shield layer  204 /insulating layer  202  could be formed by the fixation element  206  in one embodiment. 
     Regardless of how formed, the transmission line  22  is then inserted into the wire channel  100 . Next, a fixation element  206  is inserted between the wire channel  100  and the transmission cable  102 . In one embodiment, the fixation element  206  includes internal threads  207  that mate with the threads  205  of the shield layer  204 . In such an embodiment, the fixation element  206  is threaded into position. Once positioned, the wire channel  100  is fixedly bonded to the fixation element  206  by either axial welds  208  ( FIGS. 4 and 5 ) or one or more radial welds  209  ( FIG. 6 ). 
     In one embodiment, an insulating layer could be disposed between the shield layer  204  and the fixation element  206 . This layer may electrically insulate the shield layer  204  from the fixation element  206  and, thereby, electrically separate the shield layer  204  from the wire channel  100 . In such a case, it shall be understood that the internal threads  207  could still mate with the threads  205  of the shield layer  204 , but through the insulating layer. 
     An alternative embodiment of a portion of a transmission cable  300  is shown in  FIGS. 7 a  and 7 b   . The transmission line  300  in this embodiment is shown as a portion of a coaxial cable that includes an inner conductor  301  surrounded by an insulating layer such as dielectric layer  302 . It should be understood that the inner conductor  301  could be a twisted pair or an individual wire that is surrounded by an insulating layer. 
     The inner conductor  301  may be formed of a solid or braided metallic wire. The insulating layer, for example dielectric layer  302 , surrounds the inner conductor  301  for most of the length of the inner conductor  301 . The illustrated transmission cable  300  can include a shield layer (not shown) that surrounds the dielectric layer  302 . The shield layer can be formed of a highly conductive material such as copper in one embodiment and can be a braided or solid layer of material. 
     As illustrated, the insulating layer  302  includes multiple recesses  304  formed on its outer diameter. One or more fixation elements  310  can be attached to the insulating layer  302  in the recesses  304  such that the outer diameter of the fixation elements  310  is the same or slightly larger than the outer diameter of the insulating layer  302  in regions that do not include the recesses  304 . Of course, if a shield layer is present, the outer diameter of the fixation elements  310  may be the same or slightly larger than the outer diameter of the shield layer in regions that do not include the recesses  304 . The illustrated fixation elements  310  are shown as being formed of two half shells  310   a ,  310   b  but it shall be understood that these two half shells could be replaced by a fully tubular member or slotted tubular member. The assembly that includes the fixation elements  310  as shown in  FIG. 7 b    can be inserted into a wire channel to form a transmission cable. In this case, the wire channel may be welded to the fixation elements. 
     One skilled in the art will recognize that the various components or technologies may provide certain necessary or beneficial functionality or features. Accordingly, these functions and features as may be needed in support of the appended claims and variations thereof, are recognized as being inherently included as a part of the teachings herein and a part of the invention disclosed. 
     While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications will be appreciated by those skilled in the art to adapt a particular instrument, situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.