A distributed acoustic sensing system for seismic surveys, involving laying a sensing cable 2 on the seabed 22, which may receive signals from sources, attached via a riser 8 to a floating structure 3 which has instrumentation to process acquired data. The sensing part of the cable may be a single glass fibre optic (fig 5, 2a) surrounded by one or more protective layers. The protective layer may be more elastic than the sensing part and may be silicon and/or adheres to the sensing part. The protective layer may be an inner (fig 5, 2b) and outer layer (fig 5, 2c) with the outer having different tensile strength / weight / density from the inner and/or the outer layer being made of polyethylene or polypropylene. The protective layer may be biodegradable. The floating structure may have an anchor 6. The sensing cable may be connected to one or more buoys 4. The instrumentation may have a receiver for a signal to start the seismic survey.
展开▼
