Experimental design for acoustic characterization of a seismic exploration airgun array

Abstract

The Littoral Acoustic Demonstration Center (LADC) (participating institutions given in author list) is scheduled to perform an experiment in the Gulf of Mexico to characterize the underwater acoustic field of a seismic exploration airgun array. The design is constrained by the array lengths and hydrophone spacings of the ten four‐channel LADC calibrated environmental acoustic recording system (EARS) buoys available for the measurements. Placement of the EARS arrays is determined to achieve best the design goals, given the constraints. The fixed mooring EARS hydrophone depths will vary from 100 to 1171 m, and near‐surface ship‐deployed phones will be used for shallower depths. Straight‐line source boat paths of varying length and spacing have been calculated that redundantly fill all solid angle bins whose size is determined by small uncertainties in the array location and orientation [Robert Laws (2006), private communication]. Shot spacing is also a factor. Care is taken to have nearby shots to the EARS arrays for all bins. All direct paths are calculated including refraction. Data are presented in spherical and planar images to show angular and bin coverages and shot ranges. [Work supported in part by the Joint Industry Project through the International Association of Oil and Gas Producers.]