SISRAP seismic system is a device comprising one 300 m streamer.
This system can be towed at 10 knots, while the acquisition speed is limited to 5 knots for other seismic equipments.
This system can be deployed from the following ships: Thalassa, L’Atalante, Pourquoi pas ?, Marion Dufresne II.
SISRAP seismic system comprises a Sercel Sentinel RD streamer of 300 m, with FDU spacing of 6.25 m, amounting to 48FDUs.
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.
Control of immersion of the seismic streamer is achieved solely by proper balancing of the seismic streamer sections and adjustment of the length of the overhead cable. Immersion sensors at the head and tail of the seismic streamer make it possible to check the proper immersion of the streamer.
The SISRAP seismic streamer isn’t equipped with a tail buoy and the positioning of the streamer is estimated from the spun length of the head rope as well as compass data integrated at the head and tail of the streamer.
The seismic source used with the SISRAP system comprises two GI air guns (usually GI 105/105 and GI 45/45, in harmonic mode, pressure 140 bars, depth 6 m).
The air guns are towed from stanchions on each side of the ship, and built-in deflectors above the air guns ensure a depth of about 6 m for an acquisition speed of 8–10 knots.
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 Serao firing units (developed in-house by IFREMER).
