Prestack Migration in Elliptic Coordinates

Riemannian wavefield extrapolation is extended to prestack migration through the use of 2D elliptic coordinate systems. The corresponding 2D elliptic coordinate extrapolation wavenumber is demonstrated to introduce only a slowness model stretch to the single-square-root operator, enabling the use of existing Cartesian implicit finite-difference extrapolators to propagate wavefields. A post-stack migration example illustrates the advantages of elliptic coordinates in imaging overturning wavefields. Imaging tests of BP Velocity Benchmark data set illustrate that the RWE migration algorithm generates high-quality prestack migration images comparable to, or better than, the corresponding Cartesian coordinate systems.