Patent ID: 7460437

Claim:
A method of seismic data processing for migration that incorporates variations in velocity with azimuth, the method utilizing a plurality of seismic energy sources and seismic receivers located at known positions at the surface of the earth and a plurality of image points located at predetermined depths beneath the surface, each seismic energy source generating one or more seismic signals that propagate into the earth and return to the surface where the seismic signals are received by the seismic receivers, the method comprising the steps of: determining a distance from the energy source to the surface location of the image point; determining a fast travel time of the seismic signal from the energy source to the image point; determining a slow travel time of the seismic signal from the energy source to the image point; determining an azimuth angle between the energy source and the surface location of the image point; determining a first azimuth dependent travel time for the seismic signal traveling from the energy source to the image point using the fast travel time, the slow travel time, the azimuth angle of the fast velocity direction, and the azimuth angle of the energy source location to the image point location on the surface; determining a distance from the receiver to the surface location of the image point; determining a fast travel time of the seismic signal from the receiver to the image point; determining a slow travel time of the seismic signal from the receiver to the image point; determining an azimuth angle between the receiver and the surface location of the image point; determining a second azimuth dependent travel time for the seismic signal traveling from the receiver to the image point using the fast travel time, the slow travel time, the azimuth angle of the fast velocity direction, and the azimuth angle of the receiver location to the image point on the surface; calculating the total travel time for the seismic signal traveling from the energy source to the image point to the receiver by adding the first and second azimuth dependent travel times; summing the amplitudes of the input signal at the computed travel time into the output signal; repeating the foregoing steps for a plurality of image points beneath the surface of the earth for all of the energy source locations and receiver locations where signals have been recorded; calculating the total travel time for each input signal; and summing the input signal into the output image.