Abstract: A method and system for fiber optic communication and sensing (FOCS) may include transmitting one or more measurement signals from an interrogator unit that is optically connected to a proximal wavelength division multiplexer (WDM), transmitting one or more communication signals from an information handling system that is optically connected to a proximal wavelength division multiplexer (WDM), multiplexing the one or more measurement signals and the one or more communication signals with the proximal WDM into a first fiber optic cable, and receiving the one or more measurement signals and the one or more communication signals with a distal WDM that is optically connected to the first fiber optic cable. The method may further include multiplexing the one or more measurement signals from the first fiber optic cable into one or more downhole sensing fibers and receiving backscatter light from at least one of the one or more downhole sensing fibers.

Abstract: A method for distributed acoustic sensing includes sending a first optical pulse down an optical fiber, wherein light from the first optical pulse is backscattered from positions along a length of the optical fiber according to coherent Rayleigh scattering; splitting backscattered light from the first optical pulse into a first portion for a first interferometer and a second portion for a second interferometer, the first interferometer having a first gauge length and the second interferometer having a second gauge length, wherein the first gauge length is different from the second gauge length; detecting a first interferometric signal from the first interferometer responsive to the first portion of backscattered light; detecting a second interferometric signal from the first interferometer responsive to the second portion of backscattered light; and processing the first and second interferometric signals for two different sensing applications adapted for the first and second gauge lengths, respectively.