Practical issues of reverse time migration: True amplitude gathers, noise removal and harmonic-source encoding

We show that slightly modifying the conventional formulation, plus implementing an appropriate imaging condition, yields a true amplitude version of reverse time migration that provides the correct amplitude-versus-angle relation. We also discuss different ways to suppress the migration artifacts and show how noise attenuation can be handled naturally in the common reflection angle domain. Finally, we introduce a harmonic source phase-encoding method to allow a relatively efficient delayed shot or plane wave reverse time migration. Taken together, these techniques yield a powerful true-amplitude migration method that uses the complete two-way acoustic wave equation to image complex structures.