Data transmission in drilling operation environments

Abstract

Apparatus, systems, and methods may operate to transmit a data signal along a transmission line extending lengthwise along a drill string, the transmission line comprising an outer conductive path provided by a tubular wall of a drill pipe that extends along the drill string; and an internal conductive path extending along an interior passage that is bounded by a radially inner cylindrical surface of the drill pipe and along which drilling fluid is conveyed, the inner conductive path being substantially insulated from the outer conductive path. Additional apparatus, systems, and methods are described.

1 . A system comprising:
 a drill string that extends along at least part of a wellbore, the drill string comprising drill pipe having a tubular wall that is of electrically conductive material and that defines an interior passage extending along the drill string to convey drilling fluid, the drill string providing a signal transmission line that comprises:
 an outer conductive path formed by the tubular wall of the drill pipe, and 
 an internal conductive path having electrical gaps to propagate signal current through the drilling fluid and extending along the interior passage, the internal conductive path being substantially electrically insulated from the outer conductive path; and 
   a transmitter coupled to the transmission line to transmit a data signal along the transmission line.   
     
     
         2 . The system of  claim 1 , wherein at least part of the internal conductive path comprises the drilling fluid in the interior passage. 
     
     
         3 . The system of  claim 1 , wherein the drill string includes a dielectric insulator located radially between the interior passage and the tubular wall of the drill pipe, to provide electrical insulation between the internal conductive path and the outer conductive path. 
     
     
         4 . The system of  claim 1 , wherein the internal conductive path comprises a structural conductor that extends lengthwise along the drill string and is attached to the tubular wall of the drill pipe such that the structural conductor is located at or adjacent a radially outer boundary of the interior passage, when the drill pipe is viewed in cross-section. 
     
     
         5 . The system of  claim 4 , wherein the drill pipe is segmented, comprising a plurality of pipe sections that are connected together end-to-end in series, each pipe section including a conductor segment that is attached to the tubular wall of the pipe section and extends along a substantial portion of the length of the pipe section, the conductor segments of the plurality of pipe sections be arranged end-to-end in series, together to provide a segmented structural conductor extending along multiple pipe sections and forming part of the internal conductive path. 
     
     
         6 . The system of  claim 5 , wherein the segmented structural conductor further comprises a plurality of electrical connectors at respective pipe section joints, each electrical connector providing a structural electrical connection between adjacent conductor segments of neighboring pipe sections. 
     
     
         7 . The system of  claim 6 , wherein at least some of the plurality of pipe sections each have a threaded pin formation at its one end and a complementary threaded box formation at its other end, a respective electrical connector being integrated with the box formation such that connection of neighboring pipe sections by threaded engagement of their respective pin- and box formations automatically connects the conductor segments of the neighboring pipe sections through the associated electrical connector. 
     
     
         8 . The system of  claim 5 , wherein the segmented structural conductor has the electrical gaps at respective pipe section joints, at least part of each conductor segment being exposed to drilling fluid in the interior passage at the respective gaps, to propagate the signal current between adjacent conductor segments through the drilling fluid. 
     
     
         9 . The system of  claim 8 , wherein at least some pipe sections each include a protection layer that covers part of the associated conductor segment to protect the covered part of the conductor segment from exposure to drilling fluid in the interior passage, the conductor segment further comprising exposed electrodes at opposite ends of the pipe section to facilitate propagation of the signal current between adjacent electrodes through the drilling fluid. 
     
     
         10 . The system of  claim 8 , wherein at least some of the conductor segments each include an electrode adjacent each end of the respective pipe section, each electrode being annular and extending circumferentially around the interior passage. 
     
     
         11 . The system of  claim 10 , wherein a ratio between a width dimension of one of the electrodes in the longitudinal direction of the drill string and an inner diameter of the interior passage is about 0.3 to about 0.5. 
     
     
         12 . The system of  claim 10 , wherein a radially inner surface of each electrode is dimpled. 
     
     
         13 . The system of  claim 10 , wherein each conductor segment comprises a conductor strip extending lengthwise between the electrodes of the conductor segment. 
     
     
         14 . The system of  claim 10 , wherein each conductor segment comprises a coated layer of conductive material. 
     
     
         15 . The system of  claim 4 , wherein at least some of the conductor segments are each attached to a radially inner surface of a tubular liner of dielectric material that lines the associated pipe section, the liner being removably and replaceably connected to the tubular wall of the pipe section. 
     
     
         16 . The system of  claim 1 , wherein the transmitter is located in the drill string between a bottom hole assembly and a receiver above the transmitter, the system further comprising an electrical choke located in the drill string below the transmitter to inhibit downhole propagation of the data signal. 
     
     
         17 . A method for transmitting data in a drilling installation that comprises a drill string extending along at least part of a wellbore, the method comprising transmitting a data signal along a transmission line extending lengthwise along the drill string, the transmission line comprising:
 an outer conductive path provided by a tubular wall of a drill pipe that extends along the drill string; and   an internal conductive path having electrical gaps to propagate signal current through the drilling fluid and extending along an interior passage that is bounded by a radially inner cylindrical surface of the drill pipe and along which drilling fluid is conveyed, the inner conductive path being substantially insulated from the outer conductive path.   
     
     
         18 . The method of  claim 17 , wherein the internal conductive path comprises drilling fluid in the drill pipe, transmission of the data signal comprising propagating the signal current through the drilling fluid as primary conductor of the internal conductive path. 
     
     
         19 . The method of  claim 17 , wherein transmitting the data signal along the transmission line includes propagating the signal current in the internal conductive path through a structural conductor that extends lengthwise along the drill string and is connected to the tubular wall of the drill pipe. 
     
     
         20 . The method of  claim 19 , further comprising forming the drill pipe by connecting together a plurality of pipe sections, transmission of the data signal along the transmission line including propagating the signal current along a segmented structural conductor in the internal conductive path, the segmented structural conductor comprising a plurality of conductor segments that are attached to respective pipe sections and extend in series along at least a part of the length of the drill string. 
     
     
         21 . The method of  claim 20 , wherein transmitting the data signal along the transmission line includes propagating the signal current between neighboring conductor segments in the internal conductive path through respective structural electrical connectors that bridge associated pipe section joints. 
     
     
         22 . The method of  claim 20 , wherein transmitting the data signal along the transmission line includes propagating the signal current between neighboring conductor segments in the internal conductive path through the drilling fluid, to bridge the electrical gaps that separate neighboring conductor segments. 
     
     
         23 . The method of  claim 22 , wherein propagating the signal current through the drilling fluid comprises exposing only electrodes of the conductor segments to the drilling fluid, the electrodes being located adjacent opposite ends of the respective pipe sections, and portions of the conductor segments between the electrodes being covered from exposure to the drilling fluid. 
     
     
         24 . The method of  claim 20 , wherein each conductor segment comprises a coated layer of conductive material. 
     
     
         25 . The method of  claim 20 , further comprising the operation of attaching tubular liners of dielectric material to respective pipe sections, the conductor segments being carried on a radially inner surface of the respective tubular liners. 
     
     
         26 . Segmented drill pipe that, when coupled together as two or more pipe sections, provides an outer conductive path and an inner conductive path having electrical gaps to propagate signal current through the drilling fluid and to form a hybrid signal propagation path for a data signal, the outer conductive path comprising conductive material of a tubular wall of the drill pipe, and the inner conductive path comprising a combination of, on the one hand, structural conductor elements extending lengthwise along respective pipe sections and, on the other hand, drilling fluid in a fluid conduit formed by the coupled pipe sections. 
     
     
         27 . The segmented drill pipe of  claim 26 , wherein the structural conductor element of a respective pipe section comprises at least one of a conductive coating, a single solid conductor, or a conductive liner disposed lengthwise along the interior of the pipe section. 
     
     
         28 . The segmented drill pipe of  claim 27 , which includes a dielectric insulator between the tubular wall of the drill pipe and the associated structural conductor. 
     
     
         29 . The segmented drill pipe of  claim 27 , further comprising an electrical connector fastened to the pipe section to provide an electrical connection between structural conductor elements of neighboring pipe sections when the pipe sections are coupled, to bridge one of the electrical gaps between the structural conductor elements at a pipe section joint. 
     
     
         30 . The segmented drill pipe of  claim 29 , wherein the electrical connector of the pipe section is located at a threaded box end for engagement with a complimentary threaded pin and of a neighboring pipe section. 
     
     
         31 . The segmented drill pipe of  claim 27 , further comprising a protection layer that covers part of the structural conductor elements to protect the covered part of the structural conductor element from exposure to the drilling fluid, the structural conductor element further comprising exposed electrodes at opposite ends of the pipe section to facilitate propagation of current between adjacent electrodes through the drilling fluid. 
     
     
         32 . The segmented drill pipe of  claim 31 , wherein each electrode is annular and extends circumferentially around the interior of the drill pipe. 
     
     
         33 . The segmented drill pipe of  claim 32 , wherein the structural conductor element comprises a conductive coating that includes a narrow conductor strip extending lengthwise between the annular electrodes provided by the conductive coating.