Surface-Related Multiple Elimination (SRME) Berhout and Verschuur (1997); Dragoset and Jericevic (1998); Dragoset (1999); Verschuur and Berkhout (1997); Weglein et al. (1997) can be used to eliminate all multiples with at least one bounce at the water surface. SRME has been proven to be very effective when the data is finely and regularly sampled in the space coordinates and when the data aperture is sufficient to capture all surface bounces of the multiples. In many practical situations this is difficult to achieve and a large amount of data interpolation and extrapolation is required. Even when all the sampling conditions are met, SRME cannot be used to eliminate internal multiples unless the data is downward-continued to the multiple-generating layer, which in general is difficult to do for all layers.
Alvarez 2005 showed that specularly-reflected multiples have kinematics equivalent to that of primaries and therefore, when migrated with the faster velocities of the sediments, they are mapped to negative subsurface offsets in Subsurface Offset Domain Common Image Gathers (SODCIGs), if the surface offset itself is positive. Since the primaries are migrated to positive subsurface offsets when migrated with velocities slower than their exact velocities, we can in principle separate primaries from multiples in SODCIGs provided that we choose a migration velocity that is faster than the velocity of the multiples but slower than the velocity of the primaries. I explore this idea here and apply it to a simple 2D synthetic model.
The next section describes the synthetic data, the following section details the methodology, and the next section shows the results and points out some practical issues with the application of the method.