Diffraction Imaging - A Tool for Detection Small Scale Subsurface Heterogeneities

Abstract

Seismic diffraction is a carrier of information coming from subsurface objects of sub-wavelength scale. Isolating diffraction from the full wavefield and imaging them separately is a first step in establishing super-resolution of structural details. Although the importance of diffracted waved has been long time recognized in seismic exploration, in practice they are ignored in standard data processing and imaging. Naturally fractured reservoirs are an important target for the oil and gas industry. Usually information about the fractures comes from coherency cube interpretation or azimuthal analysis of the effective media. It is only seismic diffraction can directly indicate sharp structural and lithological changes in the subsurface. Separation diffraction from specular reflection in the data domain is the first step of diffraction imaging. It can be efficiently done using differences in kinematic and dynamic properties of reflected and diffracted events. At second step, focusing diffractive component allows us reliably visualize small and medium scale elements of the subsurface such as faults, pinchouts, karsts, fractures etc. I will demonstrate diffraction imaging on synthetic and real data examples.