| 摘要 |
A downhole signalling system for electrical signalling in a well installation having metallic structure in which the metallic structure is used as a signal channel. At least one magnetic material toroid 51 is provided around downhole metallic tubing 13 of the metallic structure and located between transmitting and receiving locations 43. A winding 52 is wound around the magnetic material toroid 51, and connected to a cable 53 which runs alongside the metallic tubing 13 away from the toroid 51 to replace the metallic structure as the signal channel for part of its length with the toroid 51 and winding 52 serving to transfer signals between the cable 53 and the metallic structure 12,13. |
