| 摘要 |
A system or apparatus for use in downhole communication or detection comprises a downhole arrangement defining a throughbore and primary and secondary elements. One of the primary and secondary elements is provided on the downhole arrangement and the other of the primary and secondary elements is provided in the throughbore. The primary and secondary elements are configurable for coupling of an electromagnetic field therebetween. The primary or secondary element which is provided in the throughbore may be provided on a tool such as a shifting tool which is deployable through the throughbore. The secondary element may be configured to provide the electromagnetic field coupled between the first and second elements with one or more characteristic features. The system may be configured for use, in particular though not exclusively, for communicating information to and/or from a downhole tool in an oil or gas well. |
