Performance enhancement of BOTDR fiber optic sensor for oil and gas pipeline monitoring

Distributed fiber optic sensor which based on Brillouin scattering has become increasingly popular due to its unprecedented advantage of simultaneously measuring temperature and strain. The Stimulated Brillouin Scattering (SBS) threshold, sensing distance, signal-to-noise ratio and spatial resolution are critical parameters to the performance of Brillouin Optical Time Domain Reflectometry (BOTDR) sensor. This technical paper presents the result of simulations as well as theoretical discussions on suppressing unfavorable fiber optic nonlinearity, SBS by using a statistical approach which is design of experiment (DOE). Due to the fact that there are a number of SBS threshold factors, there is a high possibility that multiple strong interactions exist among these factors. Conventional methods of plugging each factor one-at-a-time are not efficient as interactions between factors are totally ignored. The result had shown SBS suppression by 11 dB to achieve the maximum sensing distance of up to 110 km. Besides, a 3-bit simplex coding is employed when launching the laser pulses to enhance the SNR at the receiver. Simulation results demonstrated a 1.38 gain in SNR and a higher SBS threshold.