Complex-beam migration: Formulation and comparisons

A complex-beam method has been developed for shotdomain prestack depth migration. The method is flexible with input geometry and accurate in imaging multipathing arrivals. It is especially useful for depth imaging of geologically complex land areas, where data-acquisition geometries are often irregular and sparse, and topographic variations are large. Derived from the Maslov solution to the wave equation, the new method is shown to be a trueamplitude extension of the phase-shift wave-equation migration method into media with lateral velocity variations. Test results show that the new method produces depth images superior to those from Kirchhoff migration. It overcomes the dip limitation of wave-equation migration and compares well to reverse-time migration in imaging steep and overturned structures.