Absorbing boundary conditions for an acoustic wave based seismic migration

Abstract

Different absorbing boundary conditions are evaluated in a seismic migration operator which is based in the used of the linearly transformed waveequation (LITWEQ). This evaluation yields an effective methodology for reducing unwanted reflections from artificial boundaries at reduced computational cost in seismic imaging. For this specific application, first-order boundary condition developed by Higdon (1986) were found to be more stable and accurate than those of Clayton (1977) and Keys (1985). Finite-difference scheme for the chosen boundary condition was developed and successfully coupled with an explicit secondorder finite-difference formulation of LITWEQ operator. The stability condition for the resulting finite-difference scheme was evaluated via Peng and Toksoz’s transfer funtions formulation (1993) .Impulse responses show the effectiveness of the Higdon’s boundary condition for different angles of incidence at the edges of the computational domain. Finally, an application on 2D seismic data from Western Venezuelan foothills was performed. Very large reflections from the edges due to the presence of high velocity rocks at shallow depths are characteristic in imaged sections from this area. Such kind of reflections were greatly reduced by the implemented boundary condition.