Identification and focusing of edge diffractions using wavefront attributes

Abstract

Edge diffractions are more common in 3D seismic data than point diffractions; however, most current studies on processing and imaging diffractions consider point diffractions. We find that the 3D kinematic response of an edge diffractor manifests itself locally as a 2D diffraction for a specific azimuth, which can be uniquely determined using the local characteristics of the wavefronts. This applies to arbitrarily oriented curvilinear edges embedded in inhomogeneous anisotropic media. We further establish a novel 3D time-domain event classification, generalizing the existing 2D technique. A new criterion based on data-derived wavefront curvature matrices allows the unambiguous zero-offset identification of the wave scatterer types: point diffractors, edge diffractors, and reflecting boundaries. We further develop a new data-driven technique of receiver grouping to focus edge diffractions, which contributes to diffraction imaging and tomography. Both proposed methods do not rely on a priori knowledge of the subsurface. Synthetic examples validate these findings.