Visible Light Communications for Downhole Telemetry System: A Measurement-based Investigation

One of the critical components of the extracting and monitoring process in the gas and oil sector is the downhole telemetry system. As sensors resistant to high temperature and pressure have been developed, more parameters can be monitored to increase safety and efficiency. Increased bandwidth demand for downhole communications necessitated the development of a novel, dependable, and low-cost communication network. Visible light communications (VLC) have been suggested in the literature for downhole telemetry systems, since they can address the bandwidth needs thanks to the huge available spectrum. However, the gas types used in the literature so far are not sufficient enough to examine the real field conditions. In this study, after the challenges surrounding the use of VLC in downhole gas pipeline telemetry/monitoring systems are discussed, the performance of VLC is investigated by injecting a large variety of gas into the carbon steel covered gas pipeline, such as methane, and ethane, carbon dioxide. The effectiveness of the VLC system using a non-uniformly clipped optic orthogonal frequency division multiplexing (ACO-OFDM) modulation scheme with 128-FFT and guarding band is experimentally investigated. Furthermore, the impact of the light-emitting diode (LED) colors on a VLC-based downhole telemetry system is also discussed. The measurement results indicate that the color of the LED affects the performance as the dominance of the noise decreases after the 7dB signal-to-noise ratio (SNR) region.