Q‐factor Estimation and Redatuming in a Lossy Medium Using the Marchenko Equation
J.A. Brackenhoff (TU Delft - Applied Geophysics and Petrophysics)
E.C. Slob (TU Delft - Applied Geophysics and Petrophysics)
K. Wapenaar (TU Delft - Applied Geophysics and Petrophysics, ImPhys/Acoustical Wavefield Imaging )
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Abstract
Marchenko Imaging is a new technology in geophysics, which enables us to retrieve Green's functions at any point in the subsurface having only reflection data. One of the assumptions of the Marchenko method is that the medium is lossless. One way to circumvent this assumption is to find a compensation parameter for the lossy reflection series so that the lossless Marchenko scheme can be applied. The main goals of this work are to: [1] use the Marchenko equation to estimate the attenuation in the subsurface, [2] find a compensation
parameter for the lossy reflection series so that the lossless Marchenko scheme can be applied. We propose a novel approach which makes it possible to calculate an effective temporal Q‐factor of the medium between a virtual source in the subsurface and receivers at the surface. This method is based on the minimization of the artefacts produced by the lossless Marchenko scheme. Artefacts have a very specific behavior: if the input data to the Marchenko equation are over‐ or under‐ compensated, the resulting artefacts will have an opposite polarity. Thus, they can be recognized. This approach is supported by a synthetic example for a 1D acoustic medium without a free surface.