Extended FK domain migration ? An efficient variable velocity algorithm

Abstract

Constant velocity FK domain migration, as developed by Stolt in 1978, has significant performance advantages over all other commercially available migration algorithms.However, even with Stolt's pre-migration time stretching (or psuedo-depth conversion), this algorithm suffers serious accuracy problems in the presence of any significant velocity variations. This paper develops a method of extending the accuracy of FK domain migration to steep dips in arbitrary velocity fields. The basis of the new method is the partitioning of the unmigrated data set into dip ranges and computing unique time stretching factors for each. Stolt's original time stretching is shown to be the zero-dip special case of this more general algorithm. Following the separate migration of the partitions, the data is merged to form a correctly migrated data set. As few as four partitions is shown to produce very significant improvements. Even though Extended FK Domain Migration is a few times slower than conventional FK domain migration, it can still produce accuracy comparable to phase shift migration at a fraction of the cost.