Anne Paul, Michel Campillo, 2016. "Diffraction and conversion of elastic waves at a corrugated interface", Seismic Diffraction, Kamil Klem-Musatov, Henning Hoeber, Michael Pelissier, Tijmen Jan Moser
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Numerical modeling is used lo investigate the effect or small-scale irregularities of a reflecting boundary on elastic wave reflections. The scattered wave field is computed by using a discrctized form of boundary integral equations and a plane-wave decomposition of seismic wave fields. For various values of incidence angle of the P wave, we compute (he distribution of diffracted energy for both P waves and S waves as a function of reflection angle. We show that corrugations with mean wavelength of the order of. or smaller than, the seismic wavelength have little effect on the relieved P wave. However, the pattern of P-tct-5 conversion is very different from thai with a plane boundary. Scattered 5 waves appear at post critical iingles for any angle of incidence of the P wave. The amplitude of these n on geometrical shear waves decreases rapidly with decreasing amplitude of the corrugations, or when the mean wavelength of the corrugations becomes larger than the dominant seismic wavelength. The local geometry of the irregularities has u negligible cITccl on the scattered S waves. By analogy with perturbation theory, we propose interpreting the pos(critically scattered S waves as the contribution to the shear wave field of converted inhomogeneous P waves diffracted along the boundary.
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The use of diffraction imaging to complement the seismic reflection method is rapidly gaining momentum in the oil and gas industry. As the industry moves toward exploiting smaller and more complex conventional reservoirs and extensive new unconventional resource plays, the application of the seismic diffraction method to image sub-wavelength features such as small-scale faults, fractures and stratigraphic pinchouts is expected to increase dramatically over the next few years. “Seismic Diffraction” covers seismic diffraction theory, modeling, observation, and imaging. Papers and discussion include an overview of seismic diffractions, including classic papers which introduced the potential of diffraction phenomena in seismic processing; papers on the forward modeling of seismic diffractions, with an emphasis on the theoretical principles; papers which describe techniques for diffraction mathematical modeling as well as laboratory experiments for the physical modeling of diffractions; key papers dealing with the observation of seismic diffractions, in near-surface-, reservoir-, as well as crustal studies; and key papers on diffraction imaging.