| 摘要 |
The invention relates to a hollow drilling rod for transmitting information, said rod being for placing in a borehole filled with drilling mud. The rod comprises an electrically conductive cylindrical wall ( 52 <SUB>1</SUB> , 52 <SUB>2</SUB>) having an inside face, an outside face, a first end provided with a male coupling sleeve ( 62 ), and a second end provided with a female coupling sleeve ( 60 ), and being characterized in that it further comprises: a layer of electrically insulating material ( 70 ) covering the inside face over its entire length; and a conductive layer ( 80 ) covering said insulating layer and electrically connected at its ends to two electrically conductive rings, said conductive layer itself being covered by a second insulating layer ( 86 ) leaving said conductive rings in contact with the drilling mud.
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