Distributed Acoustic Sensing for Geophysical Monitoring

Distributed Acoustic Sensing (DAS), a rapidly evolving fiber-optic based technology for permanent in-well and geophysical monitoring, has been used to record VSP data in multiple Shell assets onshore Canada, USA, Europe, and the Middle East. Useful in-well velocity data were gathered from the entire length of the well from wellhead to TD (up to 4 km), which compared well with geophone recordings and sonic log data. Walk-away VSP data yield images that are nearly equivalent to images from conventional borehole geophones in terms of signal to noise ratio and resolution. Permanently installed fiber-optic infrastructure will enable low-cost non-intrusive geophysical monitoring.