Conclusions

We introduce a low-rank viscoacoustic wave extrapolation method based on the constant-$Q$ wave equation with decoupled fractional Laplacians. The proposed numerical method can handle an arbitrarily variable fractional power of the wavenumber, and thus is capable of modeling wave propagation in attenuating media with high accuracy. Using a sign reversal, we formulate a Q-compensated operator for reverse-time migration to correct for velocity dispersion and amplitude attenuation at the same time. Synthetic experiments show that the proposed method applied to viscoacoustic data produces subsurface images that are comparable in quality with the results obtained by acoustic RTM applied to acoustic data.