Near-field transient electromagnetic sounding method
(NFTES method)
The method is based on the research of the transient buildup of electromagnetic field in the rock mass while propagating square-wave direct current pulses into the ungrounded loop.
Near-field transient electromagnetic sounding method
(NFTES method)
(NFTES method)
The method is based on the research of the transient buildup of electromagnetic field in the rock mass while propagating square-wave direct current pulses into the ungrounded loop.
Near-field transient electromagnetic sounding method
(NFTES method)
(NFTES method)
The method is based on the research of the transient buildup of electromagnetic field in the rock mass while propagating square-wave direct current pulses into the ungrounded loop.
Detailed information
The duration and pattern of field transient buildup depend on rock resistivity distribution at different depths. When injecting a current pulse into transmitting loop, electromagnetic field first propagates through near-surface part of the cross-section, and then permeates depthward. The receiving loops record transient processes occuring in the environment.The field transient buildup curve and the geoelectric cross-section are plotted based on the result of processing of the records on the measured parameters. The propagation distance of the method depends on the size of the transmitting loop, the current strength in it, the particular geological situation and it can reach depths of more than 5-6 km.
Detailed information
The duration and pattern of field transient buildup depend on rock resistivity distribution at different depths. When injecting a current pulse into transmitting loop, electromagnetic field first propagates through near-surface part of the cross-section, and then permeates depthward. The receiving loops record transient processes occuring in the environment.The field transient buildup curve and the geoelectric cross-section are plotted based on the result of processing of the records on the measured parameters. The propagation distance of the method depends on the size of the transmitting loop, the current strength in it, the particular geological situation and it can reach depths of more than 5-6 km.
Detailed information
The duration and pattern of field transient buildup depend on rock resistivity distribution at different depths. When injecting a current pulse into transmitting loop, electromagnetic field first propagates through near-surface part of the cross-section, and then permeates depthward. The receiving loops record transient processes occuring in the environment.The field transient buildup curve and the geoelectric cross-section are plotted based on the result of processing of the records on the measured parameters. The propagation distance of the method depends on the size of the transmitting loop, the current strength in it, the particular geological situation and it can reach depths of more than 5-6 km.
The advantages of the new technique are the following:
uniformity of the electromagnetic field within the loop
elimination of the affect of near-surface inhomogeneities
field changes recorded within the large loop are linked only with the specifics of geological aspects (in a homogeneous environment, the field will be homogeneous), therefore it is possible to identify geological structures, tectonic faults and other geological heterogeneities with high degree of detail
unlike the conventionally used spaced measurement schemes, measurements within the loop make it possible to obtain the same type of data, undistorted by the array spread, that allows to reduce the ambiguity of data interpretation
large loop sizes provide a larger magnetic moment, which significantly increases the propagation distance and the amplitude (and hence the measurement accuracy) of the signal
high performance of field works in areal surveys
increased propagation distance allows to link the data of the near-field transient electromagnetic sounding and magnetotelluric sounding more accurately
An example of the NFTES method curve tracing and of the geoelectric cross-section build up
An example of the geoelectric cross-section
Comparison of the amplitude of curves obtained by the NFTES method, using transmitting loops 200×200 m, 500×500 m, 3000×3000 m
3D geoelectric model
Photo gallery
Photo gallery
Photo gallery