Environmental Emissions

Predicting Sound and CO2 Levels

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Modeling of the output and propagation of sound for a survey location is a routine part of modern survey planning, paired with an impact assessment for time and place. The reporting of Greenhouse Gas (GHG) emissions is also increasingly mandated and focuses on CO2.
  • Modeling of received sound levels is robust and accurate, and routinely used for the determination of safe seasonal operating windows and shutdown threshold distances in environmentally sensitive survey areas
  • CO2 emissions reporting is available for each PGS survey. Levels can be qualitatively predicted for different survey designs

 

Received sound levels, defined as sound pressure level (SPL) and sound exposure level (SEL), can be modeled within the Nucleus+ software package for any source array configuration, water depth, and for different rates of geometric spreading and decay. Specialty modeling services can also incorporate the seafloor bathymetry and seabed geoacoustic models for a survey location to model spatial variations in received sound levels. The geometric modeling from Nucleus+ will typically model the worst-case scenarios, and therefore provide robust thresholds for shutdown distances when required in environmentally sensitive survey areas.

PGS has tools to model the dynamic loads and drag of a specific acquisition configuration when planning how the trailing equipment will be deployed for specific survey designs. These tools can be used to qualitatively compare the merits of different vessel configurations in terms of drag and associated fuel consumption and CO2 emissions. Work in progress aims to predict the 'carbon budget' for a survey as a function of different key acquisition parameters. Digitalization of all vessel data assets is complete, and CO2 emissions are accurately managed and reported for surveys.

 

Peak sound pressure levels (in dB re 1 mPa) as a function of inline and crossline distance in meters from the geometric center of the source at a depth of 10 m (4 m below the source depth) for a 4130 cubic-inch array (left), and when triggering individual airguns in a near-continuous fashion (right). Spherical spreading was assumed for the rate of acoustic decay.

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