LAUSR

Distributed Acoustic Sensing (DAS) data are increasingly used in geophysics. Lower in cost and higher in spatial resolution, DAS data are appealing especially in boreholes where optical fibers are readily available. DAS has the potential to become a permanent reservoir monitoring tool with a reduced sensing time interval. In order to accomplish this goal, it is critical that DAS can record all wave modes to fully characterize reservoir properties. This goal can be achieved by recording the complete strain tensor consisting of six-components. Conventional DAS provides projections of these components along the optical fiber by observing deformation along the fiber. To obtain the entire six-component strain tensor, we propose an approach using multiple strain projections measured along optical fibers with judiciously chosen geometry specifically. We propose designs combining multiple helical configurations or a single helical configuration together with a straight optical fiber that allow access to multiple ...