Reflection reconstruction and imaging from seismic noise data for VTI media

Abstract

The application of seismic interferometry provides a new approach to obtain useful information of subsurface structures using noise data. In this study we investigate the feasibility of passive seismic interferometry in anisotropic media. We simulate long duration passive noise measurements for a model containing a transversely isotropic layer with vertical symmetry axis (VTI) using the staggered-grid finite-difference method. Then we extract the Green’s functions using the cross-correlation method. Even for VTI media, various reflections and multiples can be reconstructed, and the arrival times of these reflections correspond well with the directly modelled responses. By changing the noise source configuration and anisotropic parameters, we explore the impacts of these factors on the interferometry record. The results show that noise source configuration has considerable influence on the quality of the retrieved response, especially for S-wave reflection events. Since long time ago, passive measurements recorded from a number of noise sources provide sufficient stationary phase points to retrieve the reflections; the effect of anisotropic parameters is small. The Hess VTI model demonstrates that passive seismic interferometry is feasible to wide range of anisotropic parameters and complex subsurface structures. Moreover, a migrated image is obtained from the retrieved virtual source gathers using reverse time migration, and the subsurface structures are imaged well. The synthetic results demonstrate that passive seismic interferometry is applicable to anisotropic media and that the interferometry results can be used to image subsurface structures.