PML Absorbing Boundary Condition of Finite Element Prestack Reverse Time Migration Including Rugged Topography

Boundary reflection is an important problem of numerical simulation in limited domain. Perfectly matched layer (PML) absorbing boundary condition (ABC) is one of the best choices to eliminate boundary reflection. Generally, forward modeling needn’t consider PML ABC in free surface, but in prestack reverse time migration, false events will be appeared due to the free surface reflection, so we must consider PML ABC in free surface. The goal of this article is to derive the PML ABC formulas of second-order finite element acoustic wave equation in displacement form based on rugged topography and implement finite element numerical simulation. Several numerical simulation results are compared and show that PML ABC including rugged topography obtains a much better boundary absorption effect than that of Clayton and Engquist ABC, which verified the advantages of this method. So it can simulate seismic wave field and eliminate the fault events resulted from the free surface reflection in prestack reverse time migration including rugged topography.