Diffraction imaging of discontinuities using migrated dip-angle gathers

Abstract

Diffractions produced by subsurface geological features are an effective means of imaging small-scale discontinuities at high resolution. We developed a novel diffraction imaging approach that combines the geometric mode decomposition (GMD) algorithm and least-squares Gaussian distribution fitting (LSGDF) technique. In the dip-angle domain, reflections tend to look like smiles and are mainly focused in areas related to Fresnel zones, whereas diffractions spread over a wide illumination area due to their uniform radiation propagation. The GMD algorithm can effectively and simultaneously extract line-like components consisting of reflected energy in the Fresnel zone and diffracted energy in dip-angle gathers. The energy discrepancies between the reflection and diffraction events in the extracted line-like components allow for the separation of diffractions and suppression of reflections in dip-angle gathers using LSGDF. Numerical applications illustrate that the proposed method can eliminate large continuous reflectors and reveal discontinuous subsurface features. A real data example demonstrates the capability of the diffraction-imaging workflow in enhancing the resolving power of the imaging of subsurface geologic structures.