Seismic systems for marine surveying are widely used to explore the oceanic crust at depths ranging from several metres to several kilometres. These devices comprise an impulsive source (compressors and air guns) combined with a set of receiving sensors positioned along cables towed by the ship.
IFREMER renewed its entire fleet of seismic devices between 2014 and 2018. As a result, tree comprehensively modernized seismic systems are now available: SMT, HR and SISRAP.
These systems deploy the following:
- Sercel Sentinel RD streamers with FDU spacing of 6.25 m and the seismic data acquisition system Sercel SEAL 428 v2.
- Air guns (Sercel Ggun, GI, miniGI and Bolt) and their associated compressors.
These systems are integrated into containers (10 ft, 20 ft and 40 ft) and can be installed in various ships of the French Oceanographic Fleet.
The tree new seismic systems are as follows:
- SMT seismic system:
- A 2D system comprising a 6000 m streamer and a seismic source optimized for the acquisition of seismic reflection and refraction.
- Ships that can deploy this system: L’Atalante, Pourquoi pas ?, Marion Dufresne II.
- HR seismic system:
- A 2D or 3D device comprising two 600 m streamers.
- These two streamers can be configured differently in accordance with the scientific goals and the size of the support vessel (3D or 2D with a 600 m or 1200 m streamer).
- Ships that can deploy this system: Thalassa, L’Atalante, Pourquoi pas ?, Marion Dufresne II.
- SISRAP seismic system:
- A 2D device comprising one 300 m streamer towed at 8–10 knots.
- Ships that can deploy this system: Thalassa, L’Atalante, Pourquoi pas ?, Marion Dufresne II
These seismic systems can be deploy from other vessels than those of the French Oceanographic Fleet.
The many configurations available for the seismic systems are able to satisfy the demands of most scientific cruises which focus on environments as varied as the coast or the deep sea, and whose aims in terms of resolution and penetration depth are extremely varied.
Main characteristics of the seismic systems
The characteristics of the SMT, HR and SISRAP systems are detailed in the table below.