Antialiasing methods in Kirchhoff migration

Abstract

This paper addresses some practical aspects of antialiasing in Kirchhoff migration. We show that the effective trace spacing related to the aliasing‐frequency limits for directions between the in‐line and cross‐line directions is smaller than values previously used and that the frequency limits for antialiasing may be increased. We present a corrected expression for the migration operator spatial derivative for 3-D time migration that avoids the overfiltering at nonzero offsets produced by a previous approximation. Simple operator truncation is shown to reduce aliasing noise; it is inexpensive but may lead to errors in interpretation. Triangle filtering and Gray’s method both produce similar results, but the relative costs of these two methods will vary with the size of the migration and the computational environment. Gray’s method takes more setup time for each input trace than does triangle filtering, but Gray’s method might be more cost effective when each input trace contributes to a large number of output traces.