Device for transmitting to the surface the signal from a transmitter located at a great depth

摘要

A device for transmitting signals from a transmitter at the bottom of a drill well to the earth's surface including a drill collar which extends in an axial direction, a transmitter disposed in the drill collar, a cylindrical metal sleeve from forming part of an antenna for electromagnetic wave transmission, the cylindrical metal sleeve being disposed around the drill collar and connected electrically to the transmitter, the cylindrical metal sleeve having a diameter greater than the diameter of the drill collar and having an axial length shorter than the axial length of the drill collar, and an insulating sheath disposed between the cylindrical metal sleeve and the drill collar, the insulating sheath having an axial length shorter than the axial length of the drill collar.