Adaptive dual-sensor noise cancellation method for continuous wave mud pulse telemetry

Abstract

Mud pulse telemetry is the most commonly used method for transmitting data from downhole to the surface in measurement while drilling (MWD) systems. During the drilling process, the signal received on surface is seriously disturbed by various noise sources, among which the pump noise is the most damaging. The effective cancellation of pump noise is very essential for obtaining correct downhole information and achieving higher data transmission rates. In this paper, an adaptive noise cancellation method using two pressure transducers is studied. The method aims at complex noise environments when two or more mud pumps are used. The fundamental of the method lies on the difference in propagation direction between information signal and pump noise. An adaptive noise cancelling structure is introduced to dynamically estimate the channel characteristics between the two transducers and optimize the noise cancellation output. Both simulations and field experiments were carried out to verify the performance of the proposed method. Simulation results indicate that the method can successfully extract the information signal from pump noise with the interference of random noise from both transducers. Field experiments were carried out during a 3000-meter drilling operation. In the experiment, the major components of pump noise in frequency domain have been reduced by 49%–92%. The successful demodulation of the received data indicates that the proposed method can be used to extract downhole information in complex pump noise environment created by two triplex piston pumps.