Acoustic forward modeling of a complex geology structure with curved surface topography by grid method

Key words:  grid method  acoustic equations  forward modeling  perfectly matched layer( PML)  curved surface  irregular grid

Abstract:

Hie acoustic gird method with irregular-grid perfectly matched layer (PML) boundary was applied to forward modeling the wave field in a complex geolt^y structure featuring curved surface topography and hi^i velocity contrasts. The irregular grid, whose size is adapted to local velocity, was used to model discretization, so the curved surface and interfaces were described in details and the scattered wave usually caused by staircase approximation was avoided. Furthermore, the time over-sampling and spatial over-sampling caused by discretization with regular grid were avoided，which contributes to reducing memory and improvir^ the efficiency. By using a smoothed artificial boundary, the irregular-grid PML method and the corresponding coordinate conversion can avoid the special treatments to the comers, which leads to complex computer implementations in the conventional PML method.