Patent ID: 7994932
Filing Date: 2011-08-09
Classification: E21B

Abstract:
1. An acoustic telemetry apparatus for communicating digital data from a down-hole location through a borehole to the surface comprising: an acoustic channel terminated at a down-hole end by a reflecting terminal; an acoustic wave generator located at the surface and providing an acoustic wave carrier signal within said acoustic channel, wherein said signal is continuous; a modulator which is configured to encode said digital data as phase modulation of the reflected carrier wave, and which comprises a resonator located in the vicinity of the reflecting terminal point at said down-hole location and a valve to open and close access to the resonator to modulate phase of said carrier wave in response to a digital signal, wherein the modulator and the reflecting terminal form a phase shifting reflector for the carrier wave, switchable between one or more sensors located at the surface adapted to detect information encoded as phase modulation of acoustic waves traveling within said acoustic channel and connected to a decoding unit adapted to convert the detected information into a digital signal.