A tubular section and a system including the tubular section include a first tubular member including a threaded pin section and a second tubular member, the second tubular member including a threaded box section configured to mate with the threaded pin section. The tubular section also includes a shoulder ring disposed between the first tubular member and the second tubular member, wherein a wall thickness of at least a portion of the shoulder ring is greater than a smallest wall thickness of the threaded pin section of the first tubular member.

BACKGROUND 
     In downhole exploration and production systems, a transmission line is often used in drill pipes and with downhole tools to convey data and instructions downhole or uphole. Sections of pipes that are coupled together to extend the downhole reach of the equipment are often configured as mating pin and box pairs that thread together. Because the threads on both the pin and box sides must sometimes be re-machined, the unthreaded portion at the tip of the pin as well as at the box thread runout follow geometric rules and limitations with regard to radial design space. 
     SUMMARY 
     According to one aspect of the invention, a tubular section in a borehole penetrating the earth includes a first tubular member including a threaded pin section; a second tubular member, the second tubular member including a threaded box section configured to mate with the threaded pin section; and a shoulder ring disposed between the first tubular member and the second tubular member, wherein a wall thickness of at least a portion of the shoulder ring is greater than a smallest wall thickness of the threaded pin section of the first tubular member. 
     According to another aspect of the invention, a system to convey a tool into a borehole penetrating the earth and transfer information from the tool to another location in the borehole or to a surface of the earth includes a tubular section interfacing with the tool, the tubular section including a first tubular member including a threaded pin section; a second tubular member, the second tubular member including a threaded box section configured to mate with the threaded pin section; and a shoulder ring disposed between the first tubular member and the second tubular member, wherein a wall thickness of at least a portion of the shoulder ring is greater than the smallest wall thickness of the threaded pin section of the first tubular member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the drawings wherein like elements are numbered alike in the several Figures: 
         FIG. 1  is a cross-sectional view of a tapered threaded tubular section; 
         FIG. 2  depicts a shoulder ring placed onto a pin thread according to an embodiment of the invention; 
         FIG. 3  is a cross-sectional view of the pin thread and shoulder ring shown in  FIG. 2 ; 
         FIG. 4  depicts a shoulder ring in the box according to an embodiment of the invention; 
         FIG. 5  is a cross-sectional view of a pin shoulder ring according to an embodiment of the invention; 
         FIG. 6  is a cross-sectional view of a box end of a part-assembled tubular section according to an embodiment of the invention; 
         FIGS. 7 and 8  show inserts in the box end according to embodiments of the invention; and 
         FIG. 9  depicts a detailed view of parts within the shoulder ring according to embodiments of the invention; 
         FIGS. 10-12  depict views of an embodiment of a shoulder ring; and 
         FIG. 13  is a cross-sectional illustration of a borehole including connected tubular members according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a cross-sectional view of a tapered threaded tubular section  20 . As  FIG. 1  illustrates, when the pin thread  220  of the pin  40  and the threaded portion  15  extending from the box  30  are matched up, there may be a gap  10  at the tip of the pin  40 . This radial space or gap  10  at the tip of the pin  40  is defined by the thread ( 220 ,  15 ) profile geometry and the angle of the thread ( 220 ,  15 ) taper. Manufacturing of the tapered thread ( 220 ,  15 ) as well as repair of the thread ( 220 ,  15 ) by means of thread recut limits the pin  40  to a certain maximum radius  226  at the end of the pin  40 . This limitation additionally limits the thickness at the pin  40  end to take into consideration the competing interests of material strength (which suggests greater thickness) and design space of the pin end  225  (which suggests reduced thickness). Embodiments of the system described herein facilitate using some radial space or the gap  10  between the pin  40  and the box  30  as installation space for devices (e.g., retention mechanism, coupler) by inserting a shoulder ring  210  (see e.g.,  FIG. 2 ). During repair and recut operation the shoulder ring  210  can be removed from the threaded pin and be reinstalled. As detailed below, embodiments of the shoulder ring  210  may be used for a transmission line or for a transmission device. A transmission line includes a conductor channel (tube) and a conductor (e.g., optical fiber, coaxial cable, twisted pair wires, individual wire). A mechanical clamp affixes the conductor channel to the tool body (e.g.,  1310   FIG. 13 ). 
       FIG. 2  depicts a shoulder ring  210  placed onto a pin thread  220  according to an embodiment of the invention. The shoulder ring  210  extends from the pin end  225 . The outer diameter  230  of the shoulder ring  210  is facilitated to be larger than maximum diameter  227  (2*maximum radius  226 ,  FIG. 1 ) at the pin  40  end. The inside of the shoulder ring  210  is visible in  FIGS. 2 and 3 . Within the shoulder ring  210 , a conductor channel  240  is fixed to the shoulder ring  210 . The conductor channel  240  may be put in tension through the pin  40  side.  FIG. 3  is a cross-sectional view of the pin thread  220  and shoulder ring  210  shown in  FIG. 2 . The view shown by  FIG. 3  includes the wire  310  and a length compensating connector  320 . The greater volume provided by the shoulder ring  210  (as compared to the volume within the pin end  225  in  FIG. 1 , for example) facilitates space for coupler geometry or the retention mechanism of the conductor channel  240 , for example. 
       FIG. 4  depicts a shoulder ring  210  in the box  30  according to an embodiment of the invention. The space  420  between the shoulder ring  210  and the pin thread  220  may be occupied by an electrical frame and/or another shoulder ring  210 . The conductor channel  240  may be affixed to the shoulder ring  210  through clamping, threading, welding, soldering, gluing, or by some other mechanism. Because the coupler geometry need not be cut into the tool body and the coupler may instead be in the shoulder ring  210 , the manufacturing of the drilling or downhole tool (see e.g.  1310  in  FIG. 13 ) may be made easier through the use of the shoulder ring  210 . In addition, the shoulder ring  210  is made exchangeable or relatively easier to replace in case of wear or damage of a shoulder in the tool body or the shoulder ring  210  than if it were part of the tool body. The conductor channel  240  may be pre-assembled to the shoulder ring  210  prior to final assembly. Also, the shoulder ring  210  may be made of a different material than the pin  40  or box  30 . The shoulder ring  210  may be a higher strength material than the other components and may have sufficient strength to carry shoulder thread loads and operational loads. The shoulder ring  210  may also be made of a corrosion resistant material to prevent corrosion initiated failures at, for example, the sealing area of the coupler electrical connection. By using a non galling material for the shoulder ring  210 , galling damage may be prevented during thread makeup. 
       FIG. 5  is a cross-sectional view of a pin shoulder ring  210  according to an embodiment of the invention. While the embodiment of  FIG. 4  includes space  420  between the pin thread  220  and shoulder ring  210 , in the embodiment of  FIG. 5 , the axial length of the pin thread  220  may be reduced compared to the one displayed in  FIG. 2 , for example, and the space  420  may be eliminated. The transmission line  520  (conductor channel  240  ( FIG. 2 )) with wire  310  ( FIG. 3 )) is fed through the box side of the downhole tool.  FIG. 6  is a cross-sectional view of a box end of a part-assembled tubular section according to an embodiment.  FIG. 6  details components of the transmission device. The components include an axial load sleeve  640  and a sleeve  610 . The sleeve  610  is chosen to adjust the axial length  510  ( FIG. 5 ) of the conductor channel  240  with respect to the drillpipe internal shoulder distance that changes after e.g. recut operations. Through the use of the sleeve  610 , the need for precise tolerances that may change, based on recutting, for example, is eliminated. In the embodiment shown in  FIG. 6 , a shoulder  630  is cut directly into the drill pipe material to hold the conductor channel  240 . 
       FIGS. 7 and 8  show inserts in the box  30  end according to embodiments of the invention. The length compensation connector  620  ( FIGS. 6 and 8 ) may be chosen such that the variation in length  710  ( FIG. 7 ) after recut is eliminated and set to a fixed distance between the box  30  and connection position of the length compensation connector  620 . The sleeve  610  sits between a machined shoulder  630  of the downhole tool ( 1310 ,  FIG. 13 ) and a load sleeve  640  on the transmission line  520 . The machined shoulder  630  of the downhole tool  1310  may be straight or inclined. When inclined, the machined shoulder  630  facilitates forming a clamping set and thereby preventing any motion of the transmission line  520 . 
       FIG. 9  depicts a detailed view of parts within the shoulder ring  210  according to embodiments of the invention. The transmission line  520  may be fixed to a drilling tool using a nut  910 . The transmission line  520  may be elongated by a tensioning device  930  inserted through the pin side of the downhole tool. The nut  910  is assembled onto the threaded end of the transmission line and has to be blocked from rotating with respect to the shoulder ring  210  through the use of a lock pin  940 , for example. A second nut  920  mounted behind the nut  910  and torqued upon the nut  910  prevents the locking device from backing off during the drilling operation. The tensioning device  930  may be removed further on. Alternatively, the transmission line  520  may be set in tension using the threaded end of the transmission line  520  and the nut  910 . The pin  950  and/or screw  955  prevent the pin shoulder ring  210  from rotating when the drill pipe thread is being torqued. The pin  950  is sized to transfer this torque and to protect the conductor channel  240 . 
       FIGS. 10-12  depict views of an embodiment of a shoulder ring  210 . The embodiment shown by  FIGS. 10-12  is of a shoulder ring  210  with non-uniform thickness. As shown in  FIG. 10 , the thickness  1010  and the thickness  1020  at different parts of the shoulder ring  210  are not the same. This non-uniform thickness facilitates a larger groove to be located at the thicker portions of the shoulder ring  210  for a transmission line  520  that may carry more conductors or larger conductors than a typical transmission line  520 , for example. The non-uniform thickness may result in an inner radius of a portion (e.g., thickest portion) of the shoulder ring  210  being smaller than an inner radius of a smallest part of the threaded pin section ( 1210 ,  FIG. 12 ). The view shown by  FIG. 11  indicates that the outside of the shoulder ring  210  still has a circular cross-sectional shape while the thickness (thus the inner cross sectional shape) is non-uniform. The view shown by  FIG. 12  includes conductor channels  240  within the shoulder ring  210 . One or more conductor channels  240  may be larger or there may be more than one conductor channel  240  in a particular part of the shoulder ring  210  based on the thickness of that particular part. 
       FIG. 13  is a cross-sectional illustration of a borehole  1  including connected tubular members  1320 ,  1330  according to an embodiment of the invention. A borehole  1  penetrates the earth  3  including a formation  4 . The tubular members  1320 ,  1330  disposed in the borehole  1  are connected by a threaded portion. One or more shoulder rings  210  may be included at different places between the tubular members  1320 ,  1330  as shown in the embodiments of  FIG. 3  and  FIG. 4 , for example. Information from downhole tools  1310  such as sensors, measurement devices, or drilling tools may be telemetered or transmitted to a surface processing device  130  or any other location in the borehole. The box portion may correspond with the tool  1310  such that the shoulder ring  210  is between the tool  1310  and the tubular segment  1330 , as also shown in  FIG. 10 . Other components may be included between the tubular members  1320 ,  1330  in addition to the shoulder ring  210  for various other purposes. 
     While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.