Effects of irregular sampling on 3-D prestack migration

In a direct application of Kirchhoff migration each trace is added to the migrated volume by spreading the data along impulse response curves with suitable change in the amplitude and shape of the wavelets. Overlapping impulse responses form the correct answer where they form an envelope and are supposed to cancel elsewhere. For uniform data (constant offset, constant azimuth, constant midpoint spacing and constant velocity) the cancellation is excellent and the reflectors have the correct amplitude. This paper shows how failure to meet any of these constancy criteria results in noise. Modified summation procedures can reduce the noise at the expense of a loss of resolution.