Introduction

This short note presents the extension of the velocity-independent Stolt residual migration introduced in a previous report Sava (1999) to common-azimuth (CA) data. The derivation is very similar to its 2-D equivalent and retains the important feature of being independent of any assumption about the velocity used to obtain the image being residually migrated.

Residual migration can be used for both image improvement and velocity analysis. As was previously shown Biondi and Sava (1999), we can use the differences between a given image and an improved version of it in wave-equation velocity analysis. Since full 3-D prestack velocity analysis using the wave equation is still not within reach owing to its huge computational cost, the common-azimuth approximation seems to be the proper technology usable for 3-D datasets. It is therefore necessary to devise the appropriate residual migration tools for common-azimuth data.

In the first part of this short note I present the derivation of the common-azimuth Stolt residual migration equations, followed in the second part by a simple synthetic example.