HR seismic system is 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).
This system can be deployed from the following ships: Thalassa, L’Atalante, Pourquoi pas ?, Marion Dufresne II.
In the 2D configuration, the HR seismic system comprises a Sercel Sentinel RD streamer of 600 m or 1200 m, with FDU spacing of 6.25 m, amounting to 96 or 192 FDUs.
In the 3D configuration, the HR seismic system comprises two Sercel Sentinel RD streamers of 600 m, spaced 25 m apart. The streamers are towed from two booms extending from either side of the ship.
Data acquisition is achieved through the use of a Sercel SEAL 428 v2 acquisition system. Data is recorded in the SEG-D format.
The navigation system used is the ECOS system developed by Genavir.
The depth of the seismic streamer is controlled by ION streamer depth controllers (Compass Bird 5011-2) positioned every 150 m along the seismic streamer.
A buoy fitted with a GPS system enables the position of the streamer tail to be established.
In the HR configuration, acquisition speed is 4–5 knots.
The HR seismic source comprises several mini-GI air guns (general configuration: 2 lines of 2 mini-GI guns 24/24, 140 bars, depth 2 m, possibility of using 6 guns).
Using GI-type guns reduces bubble oscillation (no need to tune the source using different types of gun).
The air guns are towed behind the ship from the afterdeck. The guns are suspended from a buoy and their depth can be adjusted to between 1 m and 3 m.
A compressor supplies 300 m3 of compressed air per hour, which is enough to ensure a firing pressure of 140 bars every 5 seconds.
The air guns are triggered using Actris or Serao firing units (developed in-house by IFREMER).
