| 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). |
