Shallow-Water-Bottom Estimation Using Free-Surface Multiple Energy: Method and Applications

Abstract

Summary Seismic data processing and imaging has historically focused on imaging primary energy from recordings, where multiple reverberations of the free surface are considered noise and suppressed in prestack processing before depth migration. There is, however, a range of imaging and data processing challenges where standard methods are not successful in producing a good estimate of the subsurface, particularly for shallow targets under certain acquisition geometries. Multiple energy can be used in some of these scenarios, provided appropriate methods are defined to deal with the challenges associated with preprocessing and imaging free-surface multiple energy. In this context, we present a method designed to take place early in the processing stages, for which standard techniques are not sufficient to give a good interpretation of the water bottom surface, required in demultiple processing of seismic records and model building. We combine useful information from images of multiples, with special attention to preprocessing flows dealing with challenging wave modes characteristic of shallow water marine environments, to obtain a more accurate water bottom estimate, suitable for subsequent processing stages. This method is illustrated for a narrow azimuth towed streamer acquisition in a field data example from a shallow water area offshore Mexico.