Generalized approximations of reflection coefficients in orthorhombic media

Zhang, Feng; Li, Xiangyang. 2013 Generalized approximations of reflection coefficients in orthorhombic media. Journal of Geophysics and Engineering, 10 (5), 054004. https://doi.org/10.1088/1742-2132/10/5/054004

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Abstract/Summary

Reflection coefficients of qP- (quasi-P) and qS- (quasi-S) incident waves in orthorhombic media can be explicitly expressed by means of impedance matrices. In this paper, we extend previous studies and derive the generalized and linearized equations of reflectivity for all four types of waves in the symmetry-axis plane. These approximations have sufficient accuracy over a wide range of angles, therefore they are suitable for characterizing the seismic amplitude responses of unconventional resources. For example, they can be applied to represent the amplitude variation with offset for shale gas or coalbed methane reservoirs with strong anisotropy and complicated symmetry. Reduced equations are then derived in a transverse isotropic medium with a vertical symmetry axis (VTI) or a horizontal axis (HTI) for the anisotropic amplitude inversion. They retain higher accuracy than the corresponding previously published expressions at a strongly anisotropic interface, because they include the second-order terms of anisotropic parameters contrast. Numerical analyses on the inverse problem using different linearized expressions show the practical value of the new derived expressions in the joint inversion of the qPqP- and qPqS-waves for elastic parameters and anisotropic parameters.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1088/1742-2132/10/5/054004
ISSN:	1742-2132
Date made live:	02 Jan 2014 12:56 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/504379

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