Application of frequency domain induction EM soundings with controlled source (FDEMS method) for precise tracing of boundaries in geoelectrical sections

Abstract

The FDEMS method was introduced in the former USSR at the turn of the 50s and 60s of the last century as an integral part of the triad of induction EM methods (MT, FDEMS, TDEM), which were actively developed in the 50s after the grand discoveries by A.N. Tikhonov and L. Cagniard. The method was not widely used, primarily due to lack of suitable hardware and software for data processing and interpretation. Nevertheless, FDEMS was actively developed in certain regions of Russia and Ukraine until the present days. Interest in the method is supported by the potentially high accuracy of mapping high-resistivity boundaries, since in the FDEMS method there is a direct relationship between the ratio (R / H) of the sounding spacing (R) to the depth (H) to the high-resistivity reference horizon pronounced by significant points of amplitude and phase frequency characteristics (curves). A number of successful FDEMS surveys were completed on the Ukrainian Shield and its slopes, Dnipro-Donetsk basin (Ukraine) and different parts of Russia and Uzbekistan which achieved positive results (1977-2000). To date, the capabilities of modern multifunction and multichannel equipment, software for processing and interpreting field data allows to realize to a large extent the prospective capabilities of the FDEMS method for high-precision mapping of boundaries in the geoelectric section and mapping of low-contrast objects.