Study Of Wave-equation Pre-stack Migration In Angle Domain And The Extraction Of ADCIG

The wave equation prestack depth migration is a powerful tool to solve the complicated structure imaging problem. Migration velocity analysis must be well done firstly in order to get correct imaging because of the imaging quality sensitively depending on migration velocity model. ADCIG is thought to be the only gather that have no artifacts among the various imaging gather which are used to make migration velocity analysis.The thesis has carried out comparatively intensive study on angle domain prestack depth migration and the ADCIG extraction. A method of wave equation prestack depth migration that can obtain ADCIG is developed based on taking FFD for wavefield extrapolation operator, using G-D frame to decompose the wave field. This thesis has made all-round describing on how to extract ADCIG using the general migration method. The relation between migration velocity and ADCIG is analyzed and at the same time the understanding of ADCIG gets deepen.The wave equation prestack depth migration and ADCIG provide a workable strategy for complicated structure imaging. ADCIG is an admitted gather which has no artifacts. Angle domain common gather can be got from slant stacking or other methods which can covert the offset domain data to angle domain. Compared with ODCIG, ADCIG can provide more precise basic data for migration velocity analysis. Angle domain migration imaging can covert full wavefield extrapolation to local wavefield extrapolation with high describing accuracy to the propagating of wave field. The developed angle domain prestack depth migration algorithm??this paper lays emphasis on ADCIG extracting. It can realize part-wave field extrapolation by appropriate improvement. Numerical experiment indicates developed angle domain prestack depth migration algorithm here is doable. This method can generate common dip-angle image profiling and common reflection-angle image profiling .The former can be used to illumination analysis while the latter can be used to extract ADCIG. We can also make use of DSR equation or SSR equation to extract ADCIG . The two cases have higher computational efficiency after imaging. We can learn about that the ADCIG is more sensitive when migration velocity is greater than actual velocity from the relation between ADCIG and migration velocity error.