Aliasing and reverse-time migration

Ben D. Wards, Gary F. Margrave, Michael P. Lamoureux

Reverse-time migration (RTM) is a powerful migration method provided that an accurate velocity model can be constructed. In any discrete operation on a sampled field we need to consider aliasing before, during, and after that operation. Reverse-time migration takes a sampled seismic experiment and creates an image of the subsurface. In reverse-time migration the sampled wavefield and the forward modelled shotfield are propagated as a solution to the wave equation. This often requires re-sampling the data to a regular sampled and finer grid for wavefield propagation. Additionally aliasing can occur when cross-correlating the two wavefields to form an image.