3D Prestack Time Migration by Multipath Summation

A new method for 3D prestack time migration is proposed. The method is a very fast, fully automatic, macromodel-independent technique based on multipath summation of seismic traces. Contrary to the conventional techniques requiring information on migration velocities which are usually estimated by an optimization procedure for traveltime surfaces with maximum coherency, the proposed approach uses a multipath spatial summation over a range of traveltime surfaces. Thus, the multipath summation is implemented as a velocity-independent automatic procedure avoiding the need of time-consuming manual picking of velocities. The method was tested on synthetic and real data. The results of the testing show that the obtained time migration images are usually similar to those obtained using the time-consuming Kirchhoff migration. In some cases of smoothly varying velocities the multipath images may be even superior to the conventional ones.