| 摘要 |
During the course of drilling a hole, information is transmitted from the bottom by an electromagnetic wave which creates an electric current in the length of the drilling column. This column descends classically inside a first 11 and a second 21 tube which have been put into position successively as the drilling progresses. This current is measured by an inductive pick-up 13, 15 located around one of the tubes at a distance from the surface and connected to the surface by a transmission cable 16 which is cast into the cement injected around this tube. The invention applies notably to petroleum and geothermic drilling. <IMAGE>
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