A modelling comparison between received sound levels produced by a marine Vibroseis array and those from an airgun array for some typical seismic survey scenarios

Abstract

Marine Vibroseis (MV) may provide a marine seismic sound source that has less environmental impact than conventional airguns. Modelled sound levels from a realistic MV array and airgun array with similar downward energy at frequencies <100Hz were compared under three scenarios: shallow, deep, and slope. Changing the layout of the MV array's higher frequency sources reduced sound exposure levels (SELs) by 4dB. At 100m range this MV was 20dB lower in peak-to-peak sound pressure level vs. the airgun array, decreasing to 12dB lower at 5km, the maximum modelled range for peak levels. SELs were less clear-cut, but for both shallow and deep water, MV produced 8dB lower SELs than the airguns at 100km range because of MV's reduced bandwidth. Overall, MV produced lower broadband SELs, especially at long range, and lower peak pressure, especially at short range, than airguns.

Keywords: Airgun alternative; Marine Vibroseis; Marine vibrator; Noise; Quieting technology; Seismic survey.