Electric Drill Stem Telemetry

Use of the drill stem-earth system for electric down-hole-to- surface telemetry at low frequencies is considered in this article. Estimates of signal attenuation for both the perfectly conducting drill stem and a drill stem with finite conductivity are obtained and compared with previously reported work. It appears that a link of several kilometers length can be operated at frequencies in the hertz range in 10-100-Ω · m earth at power levels of the order of a few watts.