ABSTRACT

The migration of the transient electromagnetic method (TEM) has been a research topic for decades. The method, which uses the mathematical q transform to perform imaging in the wave domain, has proved its validity in some circumstances. One of the crucial steps of this kind of method is the inverse q transform, which extracts the pseudo-wave field that satisfies the wave equation from the TEM data. Conventionally, the time range of the q integral is divided into several windows and the transformation result is recovered using a regularization method, in which each window is summed up to get the final wave field. Although the recovered wave field demonstrates the key features as is indicated in the wave equation and the corresponding imaging techniques have proved to be useful, the accuracy of the extraction of these wave fields hampered the development of more accurate migration techniques. This paper will focus on the extraction of the wave field from the TEM data. A novel correlation stacking method was proposed and compared with singular value decomposition (SVD) and the pre-conditioned regularization conjugate gradient method. The comparison of the results from these methods demonstrates that the extraction results of the proposed correlation stacking method were more accurate and stable. The pseudo-seismic wave field extraction results of the actual measured TEM data showed that the correlation stacking method was the optimal method for the pseudo-seismic wave field extraction of TEM data.

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