Data transmission system for a downhole component

A system for transmitting data through a string of downhole components, each component having a first and second end, with the first end of one component connected to the second end of an adjacent component;

• the system comprising:
• a first inductive coil located at the first end of each component;
• a second inductive coil located at the second end of each component, wherein each inductive coil comprises a wire with a first end and a second end;
• a coaxial cable running between the first and second communication elements, the coaxial cable comprising a conductive tube and a conductive core within the conductive tube;
• and
• a first and second connector for connecting the first and second inductive coils respectively to the coaxial cable, each connector comprising a conductive sleeve, lying concentrically within the conductive tube, that fits around and makes electrical contact with the conductive core, the conductive sleeve being electrically isolated from the conductive tube;
• wherein the conductive sleeve of each connector is in electrical contact with the first end of the wire of the respective first or second inductive coil, and wherein the conductive tube is in electrical contact with the second end of the wire of both the first and second inductive coils.

In a system for transmitting data through a string of downhole components, the system comprising a plurality of downhole components, each with a pin end and a box end, the pin end of one downhole component being adapted to be connected to the box end of an other downhole component, each pin end comprising external threads and an internal pin face distal to the external threads, said internal pin face being generally transverse to the longitudinal axis of the downhole component, and each box end comprising an internal shoulder face with internal threads distal to the internal shoulder face, said internal shoulder face being generally transverse to the longitudinal axis of the down-hole component, and wherein the internal pin face and the internal shoulder face are aligned with and proximate each other when the pin end of the one component is threaded into a box end of the other component;

• a first communication element located within a first recess formed in each internal pin face;
• a second communication element located within a second recess formed in each internal shoulder face;
• and a conductor in communication with and running between each first and second communication element in each component;
• the improvement comprising:
• a coaxial cable as the conductor between the first and second communication elements, the coaxial cable comprising a conductive tube and a conductive core within the conductive tube;
• and
• a first and second connector for connecting the first and second communication elements respectively to the coaxial cable, each connector comprising a conductive sleeve, lying concentrically within the conductive tube, that fits around and makes electrical contact with the conductive core, the conductive sleeve being electrically isolated from the conductive tube;
• wherein the first and second communication elements each comprises a first contact and a second contact, wherein the conductive sleeve of each connector is in electrical contact with the first contact of the respective first or second communication element, and wherein the conductive tube is in electrical contact with the second contact of both the first and second communication elements.

A method of electrically connecting communication elements at opposite ends of a downhole component through a coaxial conductor, the method comprising:

• providing a coaxial cable as the conductor between the first and second communication elements, the coaxial cable comprising a conductive tube, a conductive core within the conductive tube and a dielectric material between the conductive tube and the conductive core;
• providing a first and second connector for connecting the respective first and second communication elements to the coaxial cable, wherein the first and second connectors each comprises a conductive sleeve that fits around and makes electrical contact with the conductive core, the conductive sleeve being electrically isolated from the conductive tube;
• removing a portion of the dielectric material at both ends of the coaxial cable to thereby provide clearance for the conductive sleeve;
• and
• sliding the first and second connectors over both ends of the coaxial cable.