Apparatus and method for drill pipe transmission line connections

Abstract

An apparatus for communicating a signal downhole includes a drill pipe configured to be rotated to drill the borehole and a tube under axial tension and secured in the drill pipe, wherein the axial tension occurs at least with the drill pipe not under axial tension. The apparatus further includes a connector sleeve sealed to an end of the tube and configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to. The apparatus further includes a transmission line configured to communicate the signal. The transmission line is disposed in the tube and has a length greater than the length of the tube and extending past the connector sleeve.

What is claimed is: 
     
         1 . An apparatus for communicating a signal downhole, the apparatus comprising:
 a drill pipe configured to be rotated to drill the borehole;   a tube under axial tension and secured in the drill pipe, wherein the axial tension occurs at least with the drill pipe not under axial tension;   a connector sleeve sealed to an end of the tube and configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to; and   a transmission line configured to communicate the signal disposed in the tube and having a length greater than the length of the tube and extending past the connector sleeve.   
     
     
         2 . The apparatus according to  claim 1 , wherein the transmission line is elastic such that the transmission line is stretched in order to have the length of the transmission line greater than the length of the tube. 
     
     
         3 . The apparatus according to  claim 1 , wherein the connector sleeve comprises an outer diameter that is greater than an outer diameter of the tube and is configured to contact the drill pipe to maintain the tube in the axial tension. 
     
     
         4 . The apparatus according to  claim 1 , further comprising a signal coupler configured to communicate a signal with another signal coupler disposed in an adjacent drill pipe. 
     
     
         5 . The apparatus according to  claim 4 , wherein the signal coupler comprises (a) a connector configured to seal to the sealing surface of the sleeve and (b) a signal conductor configured to communicate with the transmission line. 
     
     
         6 . The apparatus according to  claim 5 , wherein the connector comprises an O-ring configured to seal against the sealing surface of the connector sleeve. 
     
     
         7 . The apparatus according to  claim 6 , wherein the sealing surface is interior to the connector sleeve. 
     
     
         8 . The apparatus according to  claim 5 , further comprising a signal connector configured to connect the transmission line to the signal conductor. 
     
     
         9 . The apparatus according to  claim 5 , further comprising at least one of a splice, weld, and solder connection configured to connect the transmission line to the signal conductor. 
     
     
         10 . The apparatus according to  claim 3 , wherein the signal coupler is recessed in a mating surface of the drill pipe. 
     
     
         11 . The apparatus according to  claim 1 , wherein the transmission line comprises at least two electrical conductors. 
     
     
         12 . The apparatus according to  claim 1 , wherein the transmission line comprises an optical fiber. 
     
     
         13 . The apparatus according to  claim 1 , wherein the connector sleeve is sealed to the tube by at least one of a weld, an adhesive, and a friction fit. 
     
     
         14 . The apparatus according to  claim 1 , wherein the connector sleeve defines an opening configured to receive the tube. 
     
     
         15 . A method for building an apparatus for communicating a signal downhole, the method comprising:
 selecting a drill pipe;   placing a tube in axial tension, wherein the axial tension occurs at least with the drill pipe not under axial tension;   securing the tube to the drill pipe using a connector sleeve that is configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to; and   disposing a transmission line configured to communicate the signal into the tube, the transmission line having a length greater than the length of the tube and extending past the connector sleeve.   
     
     
         16 . The method according to  claim 15 , further comprising connecting a signal conductor in the connector to the transmission line using a length of the transmission line that is in excess of the tube length, wherein the signal conductor is coupled to a signal coupler configured to communicate a signal with an adjacent signal coupler disposed in an adjacent drill pipe. 
     
     
         17 . The method according to  claim 16 , wherein connecting comprises using a signal connector. 
     
     
         18 . The method according to  claim 16 , wherein connecting comprises as least one of soldering, welding and splicing. 
     
     
         19 . The method according to  claim 16 , wherein the transmission line is elastic and connecting the signal connector comprises extending the elastic transmission line in excess of the tube length. 
     
     
         20 . The method according to  claim 19 , further comprising retracting the elastic transmission line into the tube using the elasticity of the elastic transmission line. 
     
     
         21 . The method according to  claim 15 , further comprising sealing the connector to the connector sleeve with a fluid tight connection. 
     
     
         22 . The method according to  claim 21 , wherein sealing comprises using an O-ring. 
     
     
         23 . A method for communicating a signal downhole, the method comprising:
 disposing a drill pipe in a borehole; and   communicating the signal downhole using a transmission line disposed in a tube under axial tension in the drill pipe and configured to communicate the signal, the axial tension occurring at least with the drill pipe not under axial tension wherein a connector sleeve is secured to an end portion of the tube and is configured to secure the tube under the axial tension to the drill pipe and to provide a sealing surface for a connector to seal to and the transmission line has a length greater than the length of the tube and extending past the connector sleeve.