Application of VTI fast marching eikonal solver to improve seismic imaging

Sedimentary layers in the Earth's subsurface result in seismic anisotropy which makes the wave velocity dependent to the propagation angle. This phenomenon causes complexities and errors in seismic imaging such as mispositioning of migrated events. One of the challenging issues in seismic imaging is the computation of seismic wave traveltime from source to receiver via the reflection point. A powerful method to compute traveltime is applying finite difference to solve the eikonal equation. In this study, we employ a fast marching eikonal solver in isotropic and VTI concept to obtain the seismic traveltime required for Kirchhoff depth migration algorithm. Rather than using elliptical eikonal equation which is commonly used in industry, we consider an anelliptic approximation since it is more realistic and accurate. Comparing the contours of isotropic and VTI traveltimes demonstrates a considerable lateral difference of wavefronts for both conditions. After Kirchhoff imaging, results show that the VTI imaging algorithm generates images with higher resolution than the isotropic one specifically in deeper parts where reflectors are more continuous and their patterns are more clear and traceable.