Surface multiple attenuation and subsalt imaging

Abstract

Surface multiple attenuation (SMA) is a prestack, f-x domain inversion of a surface-recorded, 2-D wavefield that removes all orders of all surface multiples present within the wavefield. In addition, the process statistically determines the average acquisition wavelet. Neither of these abilities of SMA requires any assumptions regarding the positions, shapes, or reflection coefficients of the multiple-causing reflectors. Instead, SMA relies on the physical consistency between the primary and multiple events that exists in any properly recorded seismic data set. The wavefield inversion equation derives from a Kirchhoff-integral representation of the relationship between multiple events and primary events. SMA, applied to data recorded over a Gulf Coast salt-injection feature, successfully attenuated both water bottom and salt-interface multiples that contaminated reflections from the subsalt structures. With the multiples removed, imaging of the subsalt structures and subsequent interpretation became a much simpler process.