Popcorn shooting: Sparse inversion and the distribution of airgun array energy over time

Summary Airgun arrays are a standard marine seismic source. These arrays typically have a large number of individual airguns that are activated simultaneously. Allowing the activation times of individual airguns within an array to vary over an extended time period allows a greater flexibility in their use. This distribution of the activation times over time may create notches in the source signal spectra, but the sparse inversion method proposed here can restore these notches in the spectra by using information from nearby traces. If several patterns of individual airgun initiation times that do not share the same spectral zeros are used, the signal generated by a conventional source may be reconstructed with a high degree of accuracy. This method offers a significant operational advantage over other alternatives in that it uses existing equipment with minor modifications to distribute the individual airgun activation times. Among the advantages of this method is the possibility of reducing the peak amplitudes of airgun sources. In the modeled example shown here, the peak amplitude of the output signal is reduced by a factor of 10. This method may be used not only for airguns but also for other types of land and marine seismic sources. Even for airguns, the need for impulsive sources is eliminated (Ziolkowski, 1982) as long as other nearby shots contain all the desired frequencies that may be weak or missing in any one shot. This technique also allows modifications to present airgun designs and the incorporation of other seismic sources into seismic surveys to fashion source configurations that are more efficient and of better quality than present sources allow.