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Wireless measurement of sound waves while drilling

Dec 03, 2018

The transmission of sound waves or seismic signals through a drill pipe is another method of transmission. Acoustic telemetry can significantly increase the data transmission rate, increasing the data rate while drilling by an order of magnitude, up to 100bps. Acoustic telemetry, like electromagnetic wave telemetry, does not require mud circulation, and the system works with sonic propagation mechanisms. When the drill string and the drill bit interact with the bottom of the well, longitudinal elastic waves appear in the drill string. The main parameter that can be monitored is the gyro frequency of the rock breaking tool, which is mainly the vibration harmonics of the cone. Since the amplitude and frequency of the vibration are correlated with the degree of wear of the cone, the state of the tool can be judged accordingly. When the drilling procedure remains the same, the amplitude of the signal can also reflect the mechanical properties of the rock. Since the signal propagates rapidly in the drill string, a relay station is installed every 400 to 500 m in the drill string. 


Disadvantages of Acoustic Information Channels: The amount of information transmitted is small, the low-intensity signals generated by the wellbore and the acoustic noise generated by the drilling equipment make the detection signal very difficult, and the signal decays rapidly with depth.

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