| 摘要 |
<p>A method and apparatus for wireless communicating of signals within an encased borehole (14) between a downhole tool (18) and the surface (11). The tool includes conductive upper and lower tool housings (21a, 21b) which are respectively in electric contact with the conductive borehole casing. Sensors (69) within the tool generate signals which are applied to a carrier signal. The modulated carrier signal is applied via the housings to the borehole casing. The modulated signal cause a reciprocating current to flow through the borehole casing (14a) between the tool housings, inducing a voltage potential on the outside of the well-casing, which forms a dipolar electromagnetic field (30) in the earth (12) which can be received at the surface.</p> |
