Comparing DAS and DSS for Low Frequency Strain Sensing Applications

DAS has become a widespread tool for seismic and acoustic monitoring across up to 10s of km, allowing dynamic strain sensing for new and existing applications. As performance has developed, interest has extended from the seismic band (~1-100 Hz) down toward the low frequency regime (DC - ~1 Hz), where the high sensitivity of DAS has provided new capabilities for monitoring subtle slow strain changes.

This technology has been joined by DSS, which utilises Brillouin scattering to measure absolute strain along an optical fibre. DSS operates with different performance characteristics to DAS, but overlaps in detection bandwidth (up to 10 Hz), meaning there are cases where both technologies can yield different insights to the strain environment. DSS is finding applications in cases where much longer timescales are analysed, and where the interrogator is not necessarily continually measuring (an advantage of DSS).

This talk will compare DAS and DSS for different applications, with some emphasis on low frequency timescales. First, the techniques will be reviewed from a technological perspective, before giving comparative lab data to demonstrate the insights provided by each technique. Following this, some example field data will be presented, further showing the strengths of DAS and DSS, particularly for low frequency applications.