Articles from the Archive: The determination of the far-field signature of an interacting array of marine seismic sources from near-field measurements – results from the Delft Air Gun Experiment

Abstract

Data from the Delft Air Gun Experiment demonstrate the success of a new method to determine the far-field signature of a marine seismic source array from near-field measurements. The method requires the wavefield of the array to be measured in the near field with hydrophones of known relative sensitivity and in a known geometrical configuration with respect to the monopole source elements within the array. If there are n such source elements, at least n near-field hydrophones are required to determine the wavefield. The results from a North Sea line shot with a tuned airgun array show that the signature deconvolution for the wavelet calculated from these near-field measurements is at least as effective as the signature deconvolution for the measured far-field signature. The same line was shot again with the air guns out of synchronisation by as much as 100 ms; the data from the near-field hydrophones allow a deterministic signature deconvolution to be performed to yield a section very similar to that obtained with the tuned array. Without this signature deconvolution on the detuned data, the recovered section is unacceptable.