Mapping of 3-D multiples to image space: An example with a Gulf of Mexico dataset

Gabriel Alvarez

gabriel@sep.stanford.edu

ABSTRACT

I migrate a real 3D seismic dataset from the Gulf of Mexico with shot profile migration and use it to illustrate the mapping of 3D multiples from data space to image space. The dataset contains specular water-bottom multiples, peg-leg multiples associated with a large, shallow salt body, and diffracted multiples originating at the salt edges. Both the water bottom and the salt body have significant cross-line dip which makes it difficult to model the trajectory of the multiples. The location of the multiples in the image domain is severely affected by the presence of the salt and thus do not follow the geometry of the multiple-generating interface. As a consequence, some multiples could easily be interpreted as primaries. I show, by computing subsurface offsets for one sail-line, that the multiples map away from the zero-subsurface offset as they would in a purely 2D model.