Traveltime computation using the upwind finite difference method with nonuniform grid spacing in a 3D undulating surface condition

The traveltime computation scheme in a 3D undulating surface condition has a great significance to some 3D seismic data processing techniques in complex topographical regions.To obtain a traveltime computation algorithm that can treat the 3D complex topography with high accuracy and good flexibility,we present an upwind finite difference method with nonuniform grid spacing.We use the grid with nonuniform grid spacing for dividing the velocity model.For obtaining the local traveltime computation formulas,we synthetically introduce the finite difference scheme with nonuniform grid spacing,Huygens principle and Fermat principle into the conventional upwind finite difference scheme.To build up the implementation steps,we propose a new narrow-band technique in complex topographical conditions by improving the conventional narrow-band technique.The accuracy analysis and an example show that the new method can treat any 3D complex topography problems with high accuracy.