Seismic Amplitude Inversion of SV-SV Wave in VTI Media

Seismic inversion methods for PP waves in transversely isotropic media with a vertical axis of symmetry (VTI) have been extensively studied. In comparison, seismic shear waves (SV-SV and SH-SH waves) exhibit much higher sensitivity to anisotropy. Among them, the SV-SV wave in VTI media displays nonelliptical anisotropy, which is more complex than that of the SH-SH wave. Incorporating anisotropic effects in the inversion of SV-SV wave data is, therefore, crucial for accurate subsurface characterization. In this study, we propose a seismic amplitude inversion method for SV-SV waves in VTI media based on a modified approximate equation for the SV-wave reflection coefficient. This method facilitates the inversion of three key parameters: (A) vertical shear wave impedance, (B) shear modulus related to the anellipticity anisotropy parameter, and (C) vertical shear wave velocity. Additionally, the effective parameter <inline-formula> <tex-math notation="LaTeX">$\sigma $ </tex-math></inline-formula>, which governs the influence of anisotropy on the SV-wave, can be derived from these parameters. Synthetic tests demonstrate that the proposed inversion method maintains strong robustness against varying noise levels. Application to field data from a shale oil exploration area validates the method’s efficacy in recovering both elastic parameters and the anisotropic characteristics of fine layers. This work provides a reliable tool for the characterization of anisotropic reservoir formations.