Some hydrocarbon reservoirs are trapped beneath saltbodies, where seismic imaging is greatly challenged due topoor illumination. Multiple reflections have different propagationwave paths from primary reflections and thus can beused to complement the illuminations where primary reflectionsfrom beneath the salt are not acquired. Consequently,migration of multiples can sometimes provide better subsaltimages compared to conventional migration which uses primaryreflections only. In this paper,we propose to modify conventionalreverse time migration so that multiples can be usedas constructive reflection energyfor subsalt imaging. Thisnewapproach replaces the impulsive source wavelet with therecorded data containing both primaries and multiples anduses predicted multiples as the input data instead of primaryreflections. In the reverse time migration process, multiplesrecorded on the surface are extrapolated backward in timeto each depth level, and the observed data with both primariesand multiples are extrapolated forward in time to the samedepth levels, followed by a crosscorrelation imaging condition.A numerical test on the Sigsbee2B data set shows thata wider coverage and a more balanced illumination of the subsurfacecan be achieved by migration of multiples comparedwith conventional migration of primary reflections. Thisexampledemonstrates that reverse time migration of multiplesmight be a promising method for complex subsalt imaging.
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