Offset Transient Electromagnetic Virtual Wave Field Imaging Studies

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 method we have developed and enriched transient electromagnetic field connotation from one side of the wave-field, and can obtain the more advantageous information to underground target body imaging, which can not be got from the conventional transient electromagnetic method.In this article, based on the mathematical transform relationship proposed by Leebetween electric-field intensity E(t) in time-domain electromagnetic diffusionfunction and pseudo-time domain wave function, we have founded the coincidence relation between time-domain transient electromagnetic response and pseudo-time based on the large loop source according to the Maxwell functions.According to the former study, we have introduced an optimized calculation method of wave-field transform from the transient electromagnetic field into pseudo-seismic field. The comparison between numerical result and given wave-field function value shows that the method putted forward in this paper is available and useful. The massive theoretical calculation indicated: the fictitious wave-field transformed by this method not only satisfies wave functions, but also have the characteristics of the dissemination, the reflection and the transmission like the pseudo-seismic wavelet.In this article, according to the research of the resolved transient magnetic wave-field transform problem, we have created the condition of transient magnetic migration imaging. Transient electromagnetic migration imaging problem and elastic wave migration imaging problem is similar, but they are not the same. If we transform diffusion transient electromagnetic field to wave-field to deal with, we should...