METHODS AND APPARATUS FOR DOWNHOLE ACOUSTIC TELEMETRY

An improved method and apparatus for transmitting and receiving acoustic signals is presented that enables high speed transmission without repeaters. At the transmitter, a piezoelectric transducer is used to create acoustic waves through the drill string assembly walls. Transmission occurs at more t...

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Bibliographische Detailangaben
Hauptverfasser:	KIM, Seonghwan, PARK, Simon, MOON, Sangho, PAGTALUNAN, Jed
Format:	Patent
Sprache:	eng
Schlagworte:	EARTH DRILLING EARTH DRILLING, e.g. DEEP DRILLING FIXED CONSTRUCTIONS MINING OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS
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Beschreibung
Zusammenfassung:	An improved method and apparatus for transmitting and receiving acoustic signals is presented that enables high speed transmission without repeaters. At the transmitter, a piezoelectric transducer is used to create acoustic waves through the drill string assembly walls. Transmission occurs at more than one passband and each carrier frequency undergoes different modulation and channel coding schemes as the channel permits. At the receiver with multiple accelerometers with known distance, the acoustic signal is processed using several signal diversity techniques to increase the signal-to-noise ratio. A lock-in amplifier extracts the attenuated signals, and a sensor fusion estimation algorithm is performed to decrease the effect of noise. In addition, the wave speed determined from the multiple accelerometer configuration is used for cancellation of echoes and reflections.