Surface noise cancellation for acoustic downhole communication systems

This article investigates the usefulness of using two sensors and a blind-separation algorithm in reducing the effect of surface noise in downhole communication systems. The acoustic channel provides a challenging environment for the acoustic waves that propagate from the downhole to the surface of an oil or gas well. As a result, acoustic waves experience a noticeable attenuation before reaching the surface of the well. Consequently, surface noise, which is generated by the surface tools, dominates the performance of acoustic downhole communication systems that have the receiver unit close to the well surface. The application of a two-receiver noise cancellation algorithm is investigated. The article also describes a testbed that was designed to study the effectiveness of the proposed algorithm in reducing the impact of the surface noise. The communication system was built using two speakers, five connected segments of 7 inch production pipes, and two microphones. One of the speakers was used to transmit a noise-like signal in order to simulate the surface noise. The noise cancellation algorithm was applied to the outputs of the two microphones, and the quality of the acoustic signals is investigated after applying the noise cancellation solution. Results of this work emphasize the usefulness of the proposed solution in enhancing the performance of the acoustic downhole communication systems.