Patent Document ID: 6049759
Application ID: 09007977
Patent Flag: 1

Claim One:
1. A method of performing a prestack migration of seismic data, wherein there is provided a seismic survey consisting of unstacked seismic traces collected over a predetermined volume of the earth, each of said unstacked seismic traces being characterized by at least an offset from a shot, at least a portion of said unstacked seismic traces being organized into at least one common offset volume, and wherein there is provided a horizontally layered velocity model, comprising the steps of: (a) selecting a common offset volume from said at least one common offset volumes, said selected common offset volume consisting of common offset seismic traces, each of said constant offset seismic traces having a same offset from a shot; (b) calculating a 1-D time Fourier transform of each of said common offset seismic traces, thereby producing a volume of Fourier transform coefficients, said volume of Fourier transform coefficients consisting of at least one constant frequency slice; (c) selecting a constant frequency slice from said volume of Fourier transform coefficients, said constant frequency slice containing Fourier transform coefficients corresponding to a single frequency; (d) obtaining a migration operator volume calculated from said horizontally layered velocity model and said single frequency, said migration operator volume consisting of at least one planar slice; (e) selecting a planar slice from said migration operator volume; (f) calculating a 2-D convolution between said selected constant frequency slice and said selected planar slice, thereby creating a single frequency migrated slice; (g) repeating steps (e) and (f) a predetermined number of times, thereby creating a predetermined number of single frequency migrated slices, said predetermined number of single frequency migrated slices together forming a single frequency migration volume; (h) repeating steps (c) through (g) a predetermined number of times, thereby creating a predetermined number of single frequency migration volumes; and, (i) summing together said predetermined number of single frequency migration volumes, thereby producing a migrated common offset data volume for use in the geophysical exploration for hydrocarbons within said predetermined volume of the earth.