High-order Common-azimuth Depth Migration

This paper presents high-order operators for common-azimuth wave equation depth migration by wavefield extrapolation in media with strong velocity variations. The operators are derived from the approximation of the double-square-root (DSR) equation in the wavenumber domain and implemented in hybrid schemes, e.g., Fourier finite-difference (FFD) method, which contains implicit finite-difference (FD) operators in the space domain. To increase the accuracy of the migration we employ high-order approximations for the derivation of the FD operators. We test the second- and fourth-order operators on both synthetic and field datasets. The tests demonstrate that the fourth-order operators improve the image quality.