Megasource time‐domain electromagnetic sounding methods

Geophysics ◽  
1984 ◽  
Vol 49 (7) ◽  
pp. 993-1009 ◽  
Author(s):  
George V. Keller ◽  
James I. Pritchard ◽  
Jimmy Joe Jacobson ◽  
Norman Harthill
Keyword(s):  
Time Domain ◽  
Vertical Component ◽  
High Amplitude ◽  
Colorado School ◽  
Electromagnetic Sounding ◽  
The Earth ◽  
Field Versus ◽  
Time Domain Electromagnetic ◽  
Em Field ◽  
Depth Of Investigation

The Colorado School of Mines time‐domain electromagnetic (EM) sounding system makes use of a grounded length of cable powered with high‐amplitude current square waves to generate an EM field for probing the earth. The vertical component of magnetic induction is detected at a sounding site located at a relatively large distance compared to the desired depth of investigation. With a source moment of a million ampere meters or greater, offset distances of several tens of kilometers can be achieved easily, providing depths of investigation of up to 10 km. The recorded induction field versus time curves are routinely interpreted by comparison with computer‐generated theoretical curves for a layered earth. Megasource EM surveys have been carried out at The Geysers in northern California and near Yakima in central Washington, providing apparently meaningful information on the electrical structure in these areas at depths as great as 10 km.

scholarly journals Lightweight Unmanned Aerial System for Time-Domain Electromagnetic Prospecting—The Next Stage in Applied UAV-Geophysics

2021 ◽  
Vol 11 (5) ◽  
pp. 2060 ◽  
Author(s):  
Alexander Parshin ◽  
Ayur Bashkeev ◽  
Yuriy Davidenko ◽  
Marina Persova ◽  
Sergey Iakovlev ◽  
...  
Keyword(s):  
Time Domain ◽  
Gamma Ray ◽  
Pulse Generator ◽  
Measuring System ◽  
Electromagnetic Sounding ◽  
Mountainous Regions ◽  
Time Domain Electromagnetic ◽  
Unmanned System ◽  
Classical Triad ◽  
The Time Domain

Nowadays in solving geological problems, the technologies of UAV-geophysics, primarily magnetic and gamma surveys, are being increasingly used. However, for the formation of the classical triad of airborne geophysics methods in the UAV version, there was not enough technology for UAV-electromagnetic sounding, which would allow studying the geological environment at depths of tens and hundreds of meters with high detail. This article describes apparently the first technology of UAV-electromagnetic sounding in the time domain (TDEM, TEM), implemented as an unmanned system based on a light multi-rotor UAV. A measuring system with an inductive sensor—an analogue of a 20 × 20 or 50 × 50 m receiving loop is towed by a UAV, and a galvanically grounded power transmitter is on the ground and connected to a pulse generator. The survey is carried out along a network of parallel lines at low altitude with a terrain draping at a speed of 7–8 m/s, the maximum distance of the UAV’s departure from the transmitter line can reach several kilometers, thus the created technology is optimal for performing detailed areal electromagnetic soundings in areas of several square kilometers. The results of the use of the unmanned system (UAS) in real conditions of the mountainous regions of Eastern Siberia are presented. Based on the obtained data, the sensitivity of the system was simulated and it was shown that the developed technology allows one to collect informative data and create geophysical sections and maps of electrical resistivity in various geological situations. According to the authors, the emergence of UAV-TEM systems in the near future will significantly affect the practice of geophysical work, as it was earlier with UAV-magnetic prospecting and gamma-ray survey.

scholarly journals Megasource time-domain electromagnetic sounding at Poggi del Sasso - Cinigiano (GR)

1994 ◽  
Vol 37 (5 Sup.) ◽  
Author(s):  
G. V. Keller ◽  
P. Cantini ◽  
R. Carrara ◽  
O. Faggioni ◽  
E. Pinna
Keyword(s):  
Depth Profile ◽  
Time Domain ◽  
Environmental Conditions ◽  
Dipole Source ◽  
Electromagnetic Noise ◽  
Electromagnetic Sounding ◽  
Piecewise Constant ◽  
Time Domain Electromagnetic ◽  
The Time Domain ◽  
Single Set

An experiment was carried out in the vicinity of the “I Terzi” area in Southeastern Tuscany (fig. 1) to evaluate the applicability of the Time Domain Electromagnetic (TDEM) sounding method under the geological and environmental conditions prevailing in that area. An electromagnetic source was established using a motor-generator set and heavy cable. Measurements were attempted at four sites. Numerous samples of electromagnetic noise were recorded at each of these sites. At one site, signals transmitted for a grounded dipole source at 1.6 km distance were also recorded with the noise. The single set of observations has been processed and inverted to yield a six-layer piecewise constant resistivity depth-profile to a depth of about 2 km. The primary achievement of the experiment was demonstration of the praeticability of TDEM methods under the conditions prevailing in the site.

Exploration of an alluvial aquifer in Oman by time-domain electromagnetic sounding

1998 ◽  
Vol 6 (3) ◽  
pp. 383-393 ◽  
Author(s):  
M. E. Young ◽  
R. G. M. de Bruijn ◽  
A. Salim Al-Ismaily
Keyword(s):  
Time Domain ◽  
Alluvial Aquifer ◽  
Electromagnetic Sounding ◽  
Time Domain Electromagnetic

scholarly journals tTEM20AAR: a benchmark geophysical dataset for unconsolidated fluvio-glacial sediments

2021 ◽  
Author(s):  
Alexis Neven ◽  
Pradip Kumar Maurya ◽  
Anders Vest Christiansen ◽  
Philippe Renard
Keyword(s):  
Time Domain ◽  
Reliable Method ◽  
Geophysical Inversion ◽  
Quaternary Deposits ◽  
Glacial Sediments ◽  
Time Domain Electromagnetic ◽  
Inversion Techniques ◽  
Alpine Environments ◽  
The Magnetic Field ◽  
Depth Of Investigation

Abstract. Quaternary deposits are complex and heterogeneous. They contain some of the most abundant and extensively used aquifers. In order to improve the knowledge of the spatial heterogeneity of such deposits, we acquired a large (more than 1400 hectares) and dense (20 m spacing) Time Domain ElectroMagnetic (TDEM) dataset in the upper Aare Valley, Switzerland. TDEM is a fast and reliable method to measure the magnetic field directly related to the resistivity of the underground. In this paper, we present the inverted resistivity models derived from this acquisition, and all the necessary data in order to perform different inversions on the processed data (https://doi.org/10.5281/ZENODO.4269887 (Neven et al., 2020)). The depth of investigation ranges between 40 to 120 m depth, with an average data residual contained in the standard deviation of the data. These data can be used for many different purposes: from sedimentological interpretation of quaternary environments in alpine environments, geological and hydrogeological modeling, to benchmarking geophysical inversion techniques.

SNIIGGIMS AS THE INITIATOR OF SETTING-UP AN OIL-PROSPECTING ELECTRIC EXPLORATION OF NEAR-FIELD TIME-DOMAIN ELECTROMAGNETIC SOUNDING ON THE SIBERIAN PLATFORM (HISTORICAL INSIGHT)

2021 ◽  
pp. 112-118
Author(s):  
A. K. Zakharkin ◽  
Keyword(s):  
Time Domain ◽  
Siberian Platform ◽  
Near Field ◽  
Oil Exploration ◽  
Main Attention ◽  
Electromagnetic Sounding ◽  
The Core ◽  
Time Domain Electromagnetic

The article is devoted to the origin history and development of electric exploration of NFTDES (near-field time-domain electromagnetic sounding) in Siberia. The described historical insight covers the period from the mid-sixties to the mid-nineties of the last century – the period of origin, flourishing and extinction (thank God, temporary), associated with the well-known “reconstruction of our lives”. The main attention is paid to the description of events that took place within the framework of the oil exploration direction, in the midst of which the author was lucky enough to work all this time. Using the traditional terminology of 2020, this was the beginning of the “first wave” of formation and development of the Siberian school of electric exploration, the core of which was the “tandem” of electric explorers of SNIIGGiMS and IGiG SB AS USSR.

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