Compensation of transmission losses for true-amplitude reverse time migration

• The influence of transmission losses on RTM for layered media was analyzed.
• Amplitude behaviors are studied with high-frequency asymptotic analysis.
• It was proved that RTM is not true amplitude because of transmission losses.
• Transmission losses are compensated according to the theoretical derivations.
• Numerical examples confirm the theoretical derivations.

The theoretical analysis of wavefield propagators plays an important role in the development of true-amplitude migration methods. We analyze how transmission losses influence the amplitudes of reverse time migration (RTM). Based on high-frequency asymptotic theory, we analyze the change in amplitude caused by transmission losses, and prove that the transmission losses of wavefield propagation prevent RTM from yielding a true-amplitude image of the reflection coefficients. The derivations and proof provide a theoretical basis for the compensation of transmission losses in true-amplitude RTM. These theoretical derivations are then implemented in an algorithm to compensate for the transmission losses in RTM. The results from numerical experiments are consistent with the theoretical analysis. The compensation of transmission loss helps to improve the amplitude accuracy of RTM.