Broadband Environmental Source 2 (BBES2)

Offentlig prosjektsammendrag

The project objective is to develop fundamental technology for the next generation of marine seismic sources. The marine seismic source is part of the source/receiver recording system towed behind seismic vessels and used in mapping of geological structures beneath the sea bed. Airgun source arrays generate acoustic impulses that contains all frequencies (including frequencies outside the band of interest for seismic) and have served the marine seismic industry well for many years. However, the amount of energy at the very low frequencies drops typically below an acceptable level. As the spectral band is difficult to shape, the total energy needs to increase in order to be able to look deeper into the subsurface structure and to improve the geological image. Additionally, the source output signal cannot be controlled. This, in combination with the high sound pressure output of airguns, has led to restrictions on the source in many areas of the world. Marine vibrators may address these gaps but are yet to be used commercially because of reliability and efficiency issues. Both issues relate to the large vibrator plate displacement needed particularly for generating the required low frequencies. This is addressed in this project by developing different modules for different frequency bands, and by increasing the vibrator plate surface without changing the total vibrator size. The technology is inspired by the accordion and keys into the laws that controls acoustic generation in water to overcome efficiency and reliability issues. The source will emit the required energy at the very low frequencies. It will operate in the time domain, so the output will be moderate and likely not harmful to mammals. The source is electrically controllable so no energy outside the seismic frequency band of interest will be emitted. The main challenge is to demonstrate that the new source have similar or better reliability and operational safety that the current airgun have demonstrated.