Practical issues in reverse time migration: true amplitude gathers, noise removal and harmonic source encoding

Reverse time migration (RTM) is the method of choice for imaging complex subsurface structures. In this paper, we show that slightly modifying the conventional formulation, plus implementing an appropriate imaging condition, yields a true amplitude version of RTM 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.