Study on analytical method of reflection coefficient of spherical wave in VTI media

Abstract

Summary Conventional Amplitude variation with offset (AVO) forward modeling and inversion research is based on the Zoeppritz equation of plane waves theory and its various approximations. However, in actual seismic exploration, the point source excitation method is often used to generate spherical waves rather than plane waves, which is an enormous gap from the plane waves used in conventional AVO research. Especially at the near-critical angles and the over-critical angles, the difference of AVO response between spherical waves and plane waves is particularly obvious. Meanwhile, conventional seismic exploration mostly assumes that the stratum is isotropic, but actually the layer is anisotropic, the elastic parameters of the media will change with the direction. In this abstract, we derive analytical expressions for the spherical wave reflection coefficient (SRC) in VTI media based on the plane wave reflection coefficient (PRC), meanwhile, investigates the SRC within Fresnel zone in VTI media. We analyze the AVO responses of SRC versus the corresponding PRC in VTI media, showing a significant difference between them.