Patent ID: 6466873
Filing Date: 2002-10-15
Classification: G01V

Abstract:
A method of migrating seismic event data in the presence of a vertically time-varying velocity field defined by a migration velocity function, the method comprising:(a) approximating the migration velocity function by constant stepwise stage velocities V1ref, V2ref, . . . , Vnref for stages 1 through n; (b) time stretching the seismic event data to compensate for approximating the migration velocity finction by constant stepwise stage velocities, wherein a 1st set of data comprising time-stretched seismic event data for stages 1 through n results; (c) migrating the 1st set of data using a migration algorithm and using the migration velocity V1ref, wherein stage 1 migrated data results, and wherein a 2nd set of data comprising partially migrated data for stages 2 through n results; (d) successively migrating kth through nth set of data using the migration algorithm and using a residual migration velocity that is a finction of Vkref and Vkâˆ’1ref, for k=2,3 . . . , n respectively, wherein the kth set of data comprises partially migrated data for stages k through n resulting after migrating the (kâˆ’1)th set of data, and wherein stages k through n migrated data result; and (e) time unstretching the stages 1 through n migrated data, wherein a seismic event migrated data results.