Reverse Time Migration with Source Wavefield Reconstruction in Target Imaging Region

The RTM imaging condition requires the source wavefield computed in forward time be available in reverse order. Source wavefield reconstruction has been proposed to solve the problem. However, this will arouse additional computational complexity and the memory is still large for industry-size. Since RTM always requires the migration aperture to be much wider than the target imaging region when steep reflectors considered, especially for marine imaging or some special areas with complex structure, the simulation area should be wider than the target area in these cases. Therefore, in this paper, we simply perform source wavefield reconstruction within the target imaging area which we mostly concern, which means only the boundaries of this region need to be stored instead of the whole simulation area. The reconstruction computing and imaging are also limited in this domain. RTM with this scheme is verified to be effective. Both the memory requirements and computing time are reduced without losing any accuracy.