Patent ID: 11366243

Abstract:
Disclosed is a system and method for improving the performance of downhole Distributed Acoustic Sensing (DAS) systems by simultaneous use of co-propagating and counter-propagating Distributed Raman Amplification (DRA). It uses a surface DRA system with a surface DAS system to combine their laser sources where the distal end of the downhole sensing fiber use uses a Wavelength Division Multiplexer (WDM) to optically split the DRA and DAS signals onto two optical fibers. The DAS fiber/signal is terminated with a low reflectance termination to minimize a potential back reflection whereas the DRA fiber is terminated with a high reflectance termination causing all the light to reflect back up the sensing fiber. This arrangement allows for simultaneous co and counter-propagating DRA of the DAS signals, both the transmitted pulse and the back scattered light, thus creating the maximum amount of gain possible.