RIASSUNTO
Seismic surveys are created using bursts of acoustic energy that are referred to as “marine sound, or noise, depending on your perspective.”
With that thought, John Young, director of the sound business line for CSA Ocean Sciences, introduced a recent panel discussion that included seismic innovators working on new sound sources designed to produce better subsurface images as well as scientists and regulators concerned about the environmental impact of that noise. At that session and others at the recent annual meeting of the Society of Exploration Geophysicists (SEG), there was discussion about multiple ways to move away from the intense pulses of acoustic energy produced by air guns. The industry standard emits both useful sound for seismic imaging and higher-frequency noise that dissipates in the ground.
One sign that this talk may lead to alternatives to air guns for marine seismic is a joint industry project by three major oil companies backing a new generation of offshore seismic sound sources designed to reduce noise and improve the seismic signal.
Their goal is to “de-risk” vibrator technology, said Mike Jenkerson, geophysical advisor for marine seismic at Exxon Mobil, who represented the Marine Vibrator Joint Industry Project ( JIP) at the conference. The JIP managed by Texas A&M University is supporting development and testing to determine if there is an alternative to air guns that is effective and reliable even with a smaller acoustic signal.
The signal is the critical difference between sounds created using controlled vibrations and air guns, which are called impulsive sound sources and create loud, sharp booms as a large volume of air is emitted. Marine science and regulatory experts on the SEG panel indicated that research on the impact of subsea noise on sea life is likely to gradually lead to increasing limits on seismic surveys, where noise regulation is already a costly fact of life.