Marine compressed air source array primary acoustic field characterization from at-sea measurements

Area of Science:

• Marine acoustics
• Seismic exploration
• Environmental impact assessment

Background:

• Seismic surveys are crucial for resource exploration.
• Understanding the acoustic fields of seismic sources is vital for assessing marine ecosystem impacts.
• Previous models often oversimplify the complex acoustic emissions from seismic arrays.

Purpose of the Study:

• To characterize the primary acoustic field of a standard seismic survey source array.
• To calculate acoustic metrics relevant to potential impacts on marine life.
• To evaluate the reliability of distance as a predictor of acoustic exposure.

Main Methods:

• Collected calibrated acoustic data using three vertical array moorings in the Gulf of Mexico.
• Deployed a source vessel along specified survey lines for broad spatial coverage.
• Calculated acoustic metrics from recorded data, including sound pressure levels and far-field variations.

Main Results:

• Sound pressure levels showed high variability with distance, indicating distance is not a sole reliable parameter for exposure assessment.
• A simplified model accurately predicted far-field acoustic metrics along the acoustic path for specific angular bins.
• The study provides a calibrated dataset for validating and developing acoustic propagation models.

Conclusions:

• Distance is an insufficient parameter for determining marine life exposure to seismic survey noise.
• A directional, simplified model effectively predicts acoustic field variations.
• The findings support improved environmental impact assessments for seismic surveys.