Source directivity and its effects on resolution and signature deconvolution

Abstract

When a source pattern is directional, particularly in the 'in-line' direction, serious losses of high-frequency data can occur in the recorded signal at large offsets. Furthermore, since source directivity increases with frequency, signature deconvolution becomes less and less effective as one moves up the frequency band. In this artiele a controlled marine field experiment is described where the same line was shot with two source arrays, the only variable being the in-line dimension of the source pattern. Though the source was waterguns, the author believes that either sleeve airguns or marine vibrators would also have the required bandwidth to demonstrate the effect illustrated. Raw field records from the two source arrays, which have overall lengths of 30 and 10 m, are compared after filtering with a narrow bandpass filter. Thereafter constant offset sections with signature deconvolution and predictive deconvolution applied are compared for the same offsets.