Study On Extracting Early Field Of Transient Electromagnetic Method

Early signals mixed with a lot of factors response of transient electromagneticmethods uch as the first field, the impact of the metal body, the coil’s transition processwhich makes early signal transient electromagnetic method can not be used. Thus weget a blind spot area detection which we lost the geological information within it. If wecan extract the pure early secondary field signal of transient electromagnetic method,then obtain the corresponding shallow geological information, expand the detectionrange and enhance the efficiency of the construction is achievable.Becauseoftheshutdowncurrent andthecoil’s mutual inductanceandotherfactorssuch as the certain limit of the dynamic range with the instrument itself which inevitablycaused the blind spot area, we need to eliminate the blind spot area and then get earlydetection of shallow geological information. This paper describes the development andsignificance of transient electromagnetic method in shallow, analyzes the causes ofblind spot area, elaborates the basic principles of transient electromagnetic method andmine transient electromagnetic method, and simulates the response curve of the coiland the decay curve of the primary field. We used three methods such as least squaresmethod, polynomial method and Gaussian method to fit and prediction the original dataand the converted apparent resistivity data which could extract the early secondary fielddata. We analyze the advantages and disadvantages of these three fitting methods andget the distribution of mine transient electromagnetic method to detect shallow minegeological information through two application examples.