Год издания: 2017

Reverse-Time Migration (RTM) has proved to be efficient in producing good seismic images in case of complex velocity models. However, it is computationally expensive and produces artifacts when used for contrast migration velocity models. Here we present a modified algorithm for RTM addressing these issues. It is based on fast hybrid approach to finite-difference (FD) modeling of the first-arrival seismic waveforms. It is a two step procedure: first, we solve the eikonal equation for the first arrival traveltimes; second, we solve the wave equation such that at every time step the FD computations are performed only in a moving narrow strip following the first-arrival wave front. This approach to modeling results in considerable computational speed-up and memory savings when storing wavefield (only in the strip of first-arrival waveforms). Moreover, computation of the source wavefield only in a moving strip does not allow for generation of multiples in contrast models thus eliminating artifacts.