Discussion

The results of the previous sections show that primaries and multiples can be separated not only in ADCIGs but even in SODCIGs. In this case the crossline dips of the reflectors were relatively minor and little difference existed in the crossline component of the SODCIGs between the primaries and the multiples. Enough difference exists in the inline components, however, that a 2D style multiple attenuation can be carried out in the manner described by Alvarez 2006 in a companion paper in this report.

In addition, primaries and multiples can be discriminated on the basis of their residual moveouts in both pseudo as well as true 3D ADCIGs. In the first case, the discrimination is mostly in the inline component of the ADCIG since, as with the SODCIG not enough crossline dip exists in our dataset to provide a discrimination in the crossline component. Nonetheless, we can apply a Radon transform in the inline direction to separate the primaries and the multiples as done with 2D data Alvarez et al. (2004); Sava and Guitton (2003). In true 3D ADCIGs, there is the additional advantage of the multiples and the primaries behaving differently as a function of azimuth for a given aperture angle. This differential azimuth rotation may be exploited to compute a three-dimensional Radon transform that is a function of aperture angle and azimuth in a manner somewhat similar to the apex-shifted Radon transform used to attenuate 2D diffracted multiples Alvarez et al. (2004). More research is needed to work out the implementation details, but the results of our tests are encouraging.