Least Squares DAS to geophone transform

Jorge E. Monsegny, Kevin W. Hall, Donald C. Lawton, Daniel O. Trad

Distributed acoustic sensing uses optical fibre to measure strain or strain rate along the fibre direction. In contrast, geophones are equipped with a spring-mass system that measures the particle velocity in the direction of this spring-mass system. The strain rate estimated by distributed acoustic sensing is related to the total displacement of a section of the fibre called gauge length. By using this link between strain rate and displacement we propose a least squares inversion scheme to obtain particle velocity along the fibre from strain rate in a distributed acoustic sensing system. We test this least squares transformation with data from the Containment and Monitoring Institute Field Research Station in Alberta, Canada. We found that the transformed traces are very similar to a filtered version of the corresponding geophone ones, in particular at early times.