Accelerating Wave Equation Migration by Frequency Decimation

Wave equation prestack depth migration is an effective, albeit costly, approach to image the subsurface in complex areas. We demonstrate a method for reducing the computational cost of such a migration while still yielding high quality images, by decimating the input data volume in frequency. Because a monochromatic signal is able to resolve a finite bandwidth of wavenumbers in the subsurface (in the prestack case), only a small number of frequencies is required to construct the depth image. The decrease in signal-to-noise ratio is very slight, owing to high levels of noise correlation across frequencies. We show a North Sea example, in which the migration cost has been reduced by a factor of 5, without noticeable degradation of the migrated depth image.