English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Distributed Acoustic Sensing (DAS) has been limited in its use forsurface-seismic reflection measurements, due to the fiber's decreasedsensitivity when the fiber is deployed horizontally. Deploying the fiber in ahelically wound fashion has the promise of being more sensitive to broadsidewaves (e.g. P-wave reflections) and less sensitive to surface waves thanstraight fiber. We examine these claims by burying a set of straight fibers(SF) and helically wound fibers (HWF) with different wrapping angles, usingstandard and engineered fibers. These fibers were buried in a 2 m deep trenchin a farmland in the province of Groningen in the Netherlands. They are linkedup to two interrogating systems and an electrically driven vibrator was used asa seismic source. We observe in our field data that using HWF has a destructiveeffect on the surface-wave amplitudes. Our data confirmed the effect of thewrapping angle on the polarity of the surface-wave arrival and the dampeningeffect of the helical winding, both behaving in quite a predictable fashion.Apart from the effect of the wrapping angle, the different design choices, e.g.cable filling and material type, did not show a significant effect on theamplitude of the signals. As for P-wave reflections, we observe that bothengineered SF and HWF provide reflection images comparable to those obtainedfrom the geophone data despite the straight fiber's decreased broadsidesensitivity. A polarity reversal and an amplitude difference between SF and HWFfibers are observed. Finally, we show that the combined use of SF and HWFproved to be useful since SF showed better sensitivity in the shallower partand HWF in the deeper part.

Experiences with Distributed Acoustic Sensing using both straight and  helically wound fibers in surface-deployed cables -- a case history in  Groningen, The Netherlands