The main advantage of the image space is that most of the complexity of the propagation for the primary reflections is handled by prestack depth migration such that the primary reflections in Angle-Domain Common-Image Gathers (ADCIGs) are flat or nearly flat if the migration is done with the velocity of the primaries. It is not immediately obvious, however, what is the residual moveout of the migrated multiples in ADCIGs. A reasonable approximation is to consider that the residual moveout of the migrated multiples is the same as that of the primaries when migrated with the wrong (higher) velocity Biondi and Symes (2004). This approach leads, in 2D, to a relatively simple and effective algorithm for the attenuation of the multiples in the image space Sava and Guitton (2003) and, with some modifications, can attenuate 2D diffracted multiples reasonably well Alvarez et al. (2004). In this paper I present the equations for the image space coordinates of the water-bottom multiples in 2D ADCIGs and illustrate the migration of the multiples with a synthetic dataset.

The next section presents the kinematics of water-bottom and diffracted multiples in data space. The following section presents the equations to map the multiples from data space to image space. The last section illustrates the mapping of the multiples in image space, both in common subsurface offset common-image gathers and angle-domain common-image gathers for the simple synthetic dataset.

5/3/2005