Seismic airgun array directivity from far-field measurements and modeling in the Gulf of Mexico

The Gulf of Mexico supports extensive hydrocarbon exploration and production activities, where seismic airgun surveys are a persistent source of high-amplitude, low-frequency acoustic energy at basin scales. Seismic airgun arrays are inherently directional sources, producing frequency-dependent radiation patterns that vary with azimuth and dip angle. Empirical validation of directivity effects at far-field ranges has been limited. This study combines acoustic measurements with an integrated direction- and dip-dependent source and propagation model to characterize the directivity of seismic surveys in the Gulf at ranges exceeding 700 km across 15 monitoring sites. The integrated model reproduced measured airgun pulses with errors ranging from 3.3 to 5.9 dB across 15-250 Hz, with performance varying with azimuth, frequency, and propagation complexity. Gulf-wide propagation simulations extending to 1050 km demonstrated that source orientation relative to bathymetry alone restructures the spatial footprint of seismic energy at sidelobe frequencies (>100 Hz), with north-south orientations producing higher sound levels across a broader geographic area than east-west orientations at the source locations in this analysis. These results demonstrate that source directivity and bathymetry strongly influence the basin-scale distribution of seismic acoustic energy, with implications for environmental impact assessment and acoustic exposure of marine species in the Gulf.