| The study about migration imaging method in electromagnetic sounding is the focus and the advanced subject in the field. Along with the application of the seismic techniques into the transient electromagnetic method, we pay more and more attention in pseudo-seismic interpretation, electromagnetic migration imaging and the combination method of migration and inversion. Now the methods above have obtained the important development. According to the methods we have developed and enriched transient electromagnetic field connotation from one side of the wave, and can obtain the more advantageous information to underground target body imaging, which can not be got from the conventional transient electromagnetic method.Because the current predicting method cannot well detect the water-structure in front of tunnel, a useful method of prediction in front of tunnel with TEM wave-field transform and migration imaging, which solve the problem of unfavorable water-filled bodies ahead of tunnel, has been developed in this paper.This paper discussed the basic theory of wave-field transform, migration imaging and surface extension, introduced a suitable method about 3-D virtue velocity continuous analysis, solved the question of velocity extraction from measured data in migration imaging.Gived the applicable method how to work in tunnel with TEM.Also,this paper calculated a theoretical model and a application example,the result is coincided with practical condition,that is showed this method of velocity analysis is feasible and effective.In a word, by means of the theoretical model calculation and the actual data processing, we proved that the method is reasonable, and by this method, we may strengthen the recognition of underground electric interface in transient electromagnetic method, and make it possible to make fine exploration, and lay the foundation of the next research on multi-source variable focus imaging and phased array scanning exploration. |
PDF Full Text Request