Well downhole condition signalling

Abstract

A downhole tool 10 includes means for detecting a downhole condition, a capacitor bank, and a sparker. The technique is particularly useful for detecting casing collars. As the tool is passed along the well bore 11, it detects collars 12. On each detection, a part of the capacitor bank is discharged through the sparker. This generates an acoustic pulse which is transmitted through the ground (wave 14) to detectors 15, 16. The movement of the tool 10 is also monitored by a movement detector 20. The position of the tool 10 is correlated with the positions of the collars 12 by a computer 22 fed via interfacing circuitry 21. If desired, the pulses may be coded by strength, number, time spacing, etc.

Dependencies are inferred from the claim text.