Method and apparatus using a well casing for transmitting data up a well

摘要

A tool with a switch is inserted and moved down the inside of tubular-shaped and electrically conductive casing in the well. Spaced apart contacts on the tool are connected between upper and lower electrically conductive casings located on opposite sides of a high impedance separation in the casing. The switch is operated for creating a changing electrical conductance between the upper and lower casings representative of data. The electrical conductance across the high impedance separation is interrogated with an alternating current signal to retrieve the data.