Ray Analysis of Surface-Wave Interaction with an Edge Crack
Jan D. Achenbach, Arthur K. Gautesen, Daniel A. Mendelsohn, 2016. "Ray Analysis of Surface-Wave Interaction with an Edge Crack", Seismic Diffraction, Kamil Klem-Musatov, Henning Hoeber, Michael Pelissier, Tijmen Jan Moser
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A ray-theory approach is presented to analyse scattering of Rayleigh surface waves by a surface-breaking crack. The two-dimensional problem of normal incidence on an edge crack of depth J in an elastic half-space is discussed in detail. The basic diffraction mechanisms in the high-frequency range al Ihe mouth and the edge of the crack are investigated one by one on the basis of elastodynamic ray theory. The results are then superimposed to yield simple expressions Tor the back-scallered and forward-scattered Rayleigh surface waves and for the el as tody nam k s I ress-in tensity factors, in terms of reflection, transmission, and diffraction coefficients. These approximate results axe compared with exact numerical results. Ckrod agreement is observed for djA > I. where A is the wavelength of the incident surface wave. A simple formula for the inverse problem is presented, which relates the periodicity of Ihe amplitude modulation in the high-frequency range directly to the depth d of the crack.
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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.