Advancing seismic imaging: Fresnel volume migration in anisotropic and anelastic media

Abstract

Advanced seismic imaging techniques play a crucial role in generating reliable, high-resolution subsurface images across diverse applications, such as exploring hydrocarbons and minerals, characterizing geothermal reservoirs, and selecting sites for radioactive waste disposal. In this study we present the extension of the seismic imaging technique, Fresnel volume migration (FVM), to anisotropic and anelastic media. A wavefront construction method for 3D anisotropic (TTI) velocity models was employed to compute the Green's functions required for FVM. This wavefront construction method was further developed by calculating complex traveltime fields (t*) for predefined quality factor (Q) models, describing the anelastic attenuation of seismic waves. Subsequently, these resulting traveltime fields (t*) were used in the migration process to facilitate the corresponding anelastic compensation of the amplitudes. The developed method was applied to synthetic 2D data and a real 3D dataset obtained over the "Asse" salt structure in Lower Saxony, Germany (2020). The migration with anelastic compensation demonstrated a correct enhancement of amplitudes in the synthetic data. Furthermore, the application of the anisotropic FVM to the real 3D dataset resulted in a significant improvement in the imaging quality of reflectors throughout the area surrounding the salt structure. Our findings underscore the pivotal role played by considering both anisotropy and anelastic attenuation in complex 3D models for achieving a reliable and high-resolution subsurface image using the further developed FVM approach. The latter lays the foundation for subsequent quantitative analyses of reflectors and hence supporting dependable geological interpretations.