Unified Approach to Velocity Estimation and Imaging

Seismic prospecting is based on the theory of the echo. Essentially it suggests only one (time-distance) equation that always contains not less than two unknown. It creates problems that we learned to overcome by using redundant fold and multikilometer offsets. The former raises cost, the later increases departure of reflections from a hyperbolic moveout. Together they tend to decrease resolution of seismic images. A fundamental solution to the problem is attraction of one more equation. In 3D seismic imaging it can be borrowed from the theory of diffraction by an aperture. Diffraction by a limited aperture accompanies migration of each reflected wave. It may play a constructive role in seismic imaging the same way it takes place in optics. Besides, it makes possible velocity determination at any point of an areal geometry common source gather.