Directional Propagation Cancellation for Acoustic Communication Along the Drill String

A new telemetry method in oil well services uses compressional acoustic waves to transmit data along the drill string to the surface. Normal drilling operations produce in-band acoustic noise at intensities comparable to the transducer output while lossy propagation through the drill string and surface noise further degrade the signal. A single receiver system has a capacity of several hundreds bits per second. A two-receiver scheme exploits the fact that the surface noise source and the signal propagate in opposite directions to remove the downward propagating surface noise, which produces substantial increases in channel capacity. We use training with easily obtained data to determine how the signals need to be processed in a way that does not rely on knowing sensor placement or the acoustic model