Stolt residual prestack migration is a useful tool to improve the quality of the image and to perform migration velocity analysis Sava (1999, 2000); Stolt (1996). To update a PS image, we extend Stolt prestack residual migration for two different velocity fields.
The extension of Stolt residual migration for converted waves can be done in two ways. An approximate method uses two different residual velocities in each of the two square roots of the double square root equation. The exact method calculates an appropriate transformation kernel that is able to handle both velocity fields. We will discuss both ways in the theory part. Moreover, we present synthetic examples, with both constant velocity and depth variant velocity models. For constant velocity, we show that we are able to focus the image after a migration with wrong velocities. For depth-variant velocity, we show that we are able to improve the image.