Efficient and accurate traveltime computation in 3D TTI media by the fast marching method

Abstract

Summary To accurately and efficiently calculate traveltimes in 3D anisotropic media is a major technical challenge for any anisotropic pre-stack Kirchhoff depth migration. I developed an efficient, stable, and accurate algorithm to calculate first arrival traveltimes in 3D transverse isotropic media having tilted symmetry axis (TTI). This algorithm is based on a fast marching scheme to solve the eikonal equation using a finite difference (FD) method generally used to calculate first arrival traveltimes in 3D isotropic media. Numerical examples demonstrate that the newly developed algorithm is able to construct accurate first arrival traveltimes in any complicated 3D TTI model that contains a large velocity gradient and an arbitrary orientation of its axis of symmetry. This algorithm can be straightforwardly applied to any 3D Kirchhoff pre-stack depth migration and anisotropic parameter inversion in 3D TTI media.