Tutorial: RTM image enhancement; bad models and mad physics
Ian Jones, Marcin Kobylarski and John Brittan
Journal name: First Break
Issue: Vol 35, No 3, March 2017 pp. 31 - 38
Info: Article, PDF ( 1.52Mb )
Price: € 30
The final stage of a shot-based migration process is usually the imaging condition, which brings together elements of the upcoming and downgoing wavefield for each shot gather in order to form an image contribution. This procedure suffers limitations owing to the approximations made in representing the physics of the system, and in addition to that, the final summation of all shot contributions necessarily assumes that the subsurface parameter model was perfect, such that all image contributions align perfectly for summation (within a Fresnel zone), as well as ideally having recorded data that are noise free and adequately sampled. In this work, we assess the effect of unresolvable velocity error on the final image, and present a case study example of a technique for compensating for these errors via a localized phase alignment of each of the many thousands of elemental traces that can contribute to the final image.