| At present, the routine seismic data processing is poststack migration, it just can not moves dipping reflector to their true subsurface positions and collapses diffractions. The improved way is prestack partial migration. It can avoid the influence of tilted stratum and yield an improved stacked section. But velocity analysis using CMP gathers after DMO is not exact. So, it must use prestack migration imaging technology.Firstly, the paper shows the migration concepts, the basic theory of migration and so on, then I introduce two kinds of prestack migration methods which are kirchhoff integration migration and wave equation migration, also introduced to the ray tracing theory which related to calculate of travel time. Finally, The Marmousi complex fault model, the SEG salt dome model and the other two data model pre-stack depth migration imaging test show that Kirchhoff integration pre-stack depth migration method is flexible handling capacity of the target, acceptable The imaging results, high efficiency. The wave equation pre-stack depth migration can provide high precision, amplitude fidelity, but the time cost of calculation is expensive. In addition, through participating in this processing project, I summarize some recognitions and conclusions:1.Prestack time migration is not an independent process,and its imaging result is tightly related with the basic process.2.Velocity filed is a key aspect which directly affects migration result. Rational and high precise velocity model closed to the real geology is precondition to get high quality by prestack depth migration.3.We can tack both the migration quality and migration efficiency into account and choose the best value of migration aperture in the experiment. |
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