Effects of pre-processing on reverse reverse time migration: a North Sea study

摘要

Almost all conventional pre-processing is conceived with one-way wave propagation in mind. If we take into account the existence of events arising from two-way wave piopagation, then many of the underlying assumptions of mo'veout behaviour implicit in some pre-processing techniques must be re-evaluated. Using 2D synthetic data, we demonstrate that the moveout behaviour of double bounce arrivals (a class of two-way propagating events) can be compromised by pre-processing designed to remove events exhibiting 'anomalous' moveout behaviour These observations are of interest to us because we are now beginning to employ two-way migration schemes to image complex structures- However, if we continue to use conventional pre-processing techniques, we run the risk of removing the very events we are trying to image. The observations made on the basis of synthetic modelled data are extended in this work to real data examples, all from the North Sea, where in the Central Graben we commonly have steep-sided salt diapir pier cements, which are good candidates for producing useful double bounce arrivals that can be imaged using reverse time migration.