Performance evaluation on seismic depth migration using local Born and local Rytov approximations

摘要

Due to the recent demand for high quality imaging in a reflection seismic survey, the prestack depth migration is used as a routine processing now. The Kirchoff method based on ray-tracing are used for the purpose mainly because of the computation efficiency. The use of the migration method based on wavefield extrapolation, which is thought to be more accurate but time-consuming, comes into sight along with the rapid advance in computer technology. Huang et al. (1999a, 1999b) recently proposed a new migration algorithm using the Born and Rytov approximations. Their method uses these approximation to calculate the wavefield of a certain depth level from the previous level.In this paper, the depth migration method based on these approximations are evaluated in term of the accuracy and the computation time using the synthetic poststack and prestack dataset. The migrated images are compared to those obtained by using other depth migration methods, such as the split-step Fourier method (SSF), the phase-shift plus interpolation method (PSPI) and the finite-difference method (FD) From the result of the numerical study, it is concluded that the migration method using the Rytov approximation is superior to that using the Born approximation with respect to the accuracy, the stability and the computational time. These methods can be located between PSPI, which is the most accurate but the slowest, and SSF and FD, which are faster but less accurate.