Simplified Nonhyperbolic Moveout Formula for a Transversely Isotropic Medium

Abstract

A new methodology of skew hyperbolic moveout analysis has been proposed to obtain the velocity model of reflection trafectories through an anisotropic medium. The original skew formula describes the trajectory in three velocity parameters. Conformation from the skew hyperbolic analysis suggested that one of the velocity parameters in the skew formula can be omitted/replaced. Furthermore, the moveout curve of nonhyperbolic analysis could also be analyzed by using only two velocity parameters. With one less parameter, we, therefore, call the modified skew formula a simplified nonhyperbolic moveout formula.

To ascertain the practicality of our new formula, experiments were done through an isotropic (plexiglas) block and an anisotropic (phenolite) block. A semblance analysis using the simplified formula was then applied to scan the recordings. For transverse isotropy of periodic interleaving of isotropic layers, the moveout velocity as deriven from reflection seismology contains vertical and horizontal components. The vertical component can be applied to perform time-to-depth conversion, and the anisotropy sensitive velocity ratio of horizontal-to-vertical can be used to investigate lithology or physical properties of the subsurface datum.

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