Traveltime Computation and Imaging from Rugged Topography in 3D TTI media

Traditional poststack/prestack migration procedures fail to work well in mountain areas because of the severe variations of the move-out and the low signal to noise ratio (SNR) data. A 3D dynamic programming approach to first-arrival traveltime computation is extended to anisotropic media with rugged topography, which is a key step of the working flow of PSDM in mountain areas. The traveltime computation method based on Fermat’s principle uses simple calculus techniques and a systematic mapping scheme to determine first arrival time on every uniform grid, which has no limitation on large velocity contrast and spatial variation anisotropic parameters. The numerical results of the over-thrust TTI model demonstrate that the traveltime computation method is correct and effective. The imaging results of 3D field data demonstrate that choosing a smooth datum to remove the high wavenumber move-out components and take consider of anisotropy are necessary in mountain areas.