Monitoring industrial acoustics with distributed acoustic sensing

Abstract

True-phase distributed acoustic sensing (DAS), a technique which uses low-power laser pulses to monitor along-fiber strain in optical cable, has proven useful in many geophysical research areas, including down-hole monitoring in oil/gas extraction, near-surface characterization, detecting and locating regional and global earthquakes, urban monitoring. Most of the geophysical applications to date, however, have focused on recording elastic waves propagating through solid media. In this work, we explore the response of DAS for recording acoustic propagation in air, as a function of fiber type and configuration, over frequency bands useful for monitoring industrial environments. We also present methods of creating simple fiber-composite sensing units for improving sensitivity, and strategies for combining solid-earth and acoustic monitoring to create an effective seismoacoustic array with a single DAS interrogator.