The majority of offshore seismic operations currently involve the application of towed streamer 2/3D common depth point (CDP) reflection technique. It is a powerful and very productive research tool. However, autonomous bottom recording systems have several advantages over towed streamers. The most crucial are as follows:
1. 2D/3D-4C multicomponent acquisitions;
2. Full-azimuth and full-offset acquisitions with a sparsely spaced receivers and sources;
3. No influence of the water layer on the data quality;
4. Ability to perform operations in the areas with complicated engineering infrastructure (surface and underwater), in difficult ice conditions, intensive fishing zones, etc.;
In some cases, the use of autonomous bottom recording systems in tandem with conventional towed streamer CDP reflection operations can give good results.
The table shows the main advantages of using ocean bottom nodes versus towed streamers.
Our company conducts the following types of seismic surveys offshore (at depths up to 500 m):
Multicomponent seismic survey 2D/3D-4C CDP seismic reflection method;
Regional and super-regional operations using refraction/reflection seismic technique with simultaneous recording the reflected, refracted and converted waves on extra-long reception lines;
Additional (to conventional CDP reflection seismic) bottom recording at large distances for estimating the medium velocity model and subsequent pre-stack depth migration.
To perform these surveys, the Sea Lion seismic systembased on autonomous ocean bottom nodes is used.