IMAGING COMPLEX GEOLOGIC STRUCTURE WITH SINGLE-ARRIVAL KIRCHHOFF PRESTACK DEPTH MIGRATION

We compare various forms of single-arrival Kirchhoff prestack depth mi gration to a full-waveform, finite-difference migration image, using s ynthetic seismic data generated from the structurally complex 2-D Marm ousi velocity model. First-arrival-traveltime Kirchhoff migration prod uces severe artifacts and image contamination in regions of the depth model where significant reflection energy propagates as late or multip le arrivals in the total reflection wavefield. Kirchhoff migrations us ing maximum-energy-arrival traveltime trajectories significantly impro ve the image in the complex zone of the Marmousi model, but are not as coherent as the finite-difference migration image. By carefully incor porating continuous phase estimates with the associated maximum-energy arrival traveltimes, we obtain single-arrival Kirchhoff images that a re similar in quality to the finite-difference migration image, Furthe rmore, maximum-energy Green's function traveltime and phase values cal culated within the seismic frequency band give a Kirchhoff image that is (1) far superior to a first-arrival-based image, (2) much better th an the analogous high-frequency paraxial-ray Green's function image, a nd (3) closely matched in quality to the full-waveform finite-differen ce migration image.