Wave-equation multiple imaging (WeMi) — Swimming between the flags

Abstract

Deghosting dual-sensor streamer seismic data requires separation of the total recorded wavefield into upgoing and downgoing components during seismic preprocessing. Imaging of multiples exploits the wavefield separation process by using the downgoing wavefield at each receiver location as a virtual source. Multiple imaging has been shown to effectively remove shallow-acquisition-related artifacts commonly seen on wide-tow marine seismic surveys and improve imaging quality of the shallow overburden. Acquisition design factors, imaging condition, and cross-talk noise are the main factors that determine the effectiveness of separated wavefield imaging (SWIM) of dual-sensor streamer data. (SWIM is a common nontrademarked acronym used in the literature to describe multiple imaging of separated wavefields sampled from dual-sensor streamer data.) In a field trial, acquisition design did not allow for proper sampling of the total wavefield, with the result that multiple imaging did not prove to be as robust a technique as examples in the literature might imply. Understanding the effects of acquisition design parameters on image quality is essential to more successfully apply multiple-imaging techniques with greater relevance on the North West Shelf of Australia.