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Imaging Effect Analysis Of The Special Waves Based On Reverse-time Migration

Posted on:2015-02-27Degree:MasterType:Thesis
Country:ChinaCandidate:P P WangFull Text:PDF
GTID:2180330503455864Subject:Earth Exploration and Information Technology
Abstract/Summary:PDF Full Text Request
The special waves, such as multiples, prismatic waves and diving waves, are producted by all kinds of specific underground structures and maybe they contain the information the primaries do not have. So this paper starts from the special waves’ s effective usage and use the reverse-time migration to image the seismic information contained by the special waves from different perspectives in order to get more abundant information in addition to conventional primaries. I think this paper’s research provides a new ideas and directions for positively using the information of the special waves in addition to supress them.Multiple reverse-time migration is converting each detector to a virtual point source whose record time length is the same with the detector’s record time, these virtual point sources are extrapolating downward, while the predicted free-surface multiples are reverse extrapolating downward, when they reach the same time point, they cross-correlation with each other to get the imaging result. Thtough the principle feasibility analysis, the imaging condition and the noise analysis, the lighting range analysis, the imaging effect analysis of complex models and the actual data imaging analysis, we deeply understand the role of multiples in reverse-time migration and get the more accurate and wider rich imagings of the underground structures. It has better lighting to the deep structures, especially in the case of the same migraion aperture, it gets the better imaging effect of the flanks with steep dip angles.Prism wave reverse-time migration is a new method for imaging salt flanks with prism wave reflections. There are two steps to the method:(1)Conventional RTM is applied to the data to estimate the geometry of the horizontal reflections near the salt flank;(2)Prism wave RTM is applied to the data again, except the prism imaging condition is used rather than the conventional one. Prism wave RTM can make full use of prismatic wave information to correctly image the prismatic waves producd by the salt flanks. So in the description of the salt dome flanks’ s vertical boundary, prism wave RTM can play a important role.We use the RTM to image the diving waves from the BP model and analysizes the imaging effect. RTM can correctly image the diving waves and has better imaging effect for the upper interface of salt, salt body internal structures and salt flanks with steep angles. RTM is a strong technique to resolve the imaging of the salt body and the salt dome shade structures.
Keywords/Search Tags:reverse-time migration, multiple reverse-time migration, prism wave reverse-time migration, diving wave, imaging effect analysis
PDF Full Text Request
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