MATHEMATICAL MODELING OF TRANSIENT ELECTROMAGNETIC SOUNDING SIGNALS FOR MONITORING THE STATE OF PERMAFROST
M.N. Nikitenko1, V.N. Glinskikh1,2, I.V. Mikhaylov1, A.A. Fedoseev1
1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: Electromagnetic monitoring, TEM sounding, cryolithozone, cross-borehole exploration, geoelectric model, numerical simulation, integration of a rapidly oscillating function
Abstract
The study is aimed at the theoretical development and scientific substantiation of a high-resolution transient electromagnetic (TEM) geophysical technique for monitoring the state of permafrost. The electromagnetic-monitoring configuration includes spatially distributed sounding systems for the surface and borehole locations of the field sources and receivers. Changes in the electrophysical properties of the earth can be traced for the cases of both ground thawing and freezing. We developed the theory of TEM signals modeling, which served as the basis for an algorithm for rapid and accurate numerical simulation of the electromagnetic field. The signals are scrutinized from various sounding systems in the basic earth models as a function of recording time. We show how the features associated with the spatial arrangement of frozen rocks appear in the emf diagrams. It follows that a set of the measured data enables visual detection of the boundary between frozen and thawed rocks.
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