Enhancing Seismic Imaging of Deep Structures Using Anelliptic VTI Traveltimes

Abstract

The presence of sedimentary layers in the Earth's subsurface results in seismic anisotropy, which makes wave velocity dependent on the propagation angle. This aspect causes errors in seismic imaging such as mispositioning of migrated events if anisotropy is not accounted for. One of the challenging issues in seismic imaging is the estimation of anisotropy parameters which usually has error due to dependency to several elements such as sparse data acquisition, erroneous data with low signal to noise ratio, etc. In this study, an isotropic and anelliptic VTI fast marching eikonal solvers are employed to obtain seismic traveltimes required for Kirchhoff depth migration algorithm. Computing cost of fast marching method is O(NlogN) which is faster than the general finite difference methods with cost of O(N2). The Sigsbee synthetic data and a real dataset are used for testing purposes. The comparison of isotropic and VTI traveltimes demonstrates a considerable lateral difference among wavefronts. The results of Kirchhoff imaging show that the VTI algorithm generates images with perfect positioning and higher resolution than the isotropic one, specifically in deep areas. Finally, we conclude that our anisotropic approach is stable, fast, and generates high-quality images with accurate details in deep structures.