TAKING INTO ACCOUNT THE INFLUENCE OF THE UPPER PART OF THE SECTION ON THE RESULTS OF AUDIOMAGNETOTELLURIC SOUNDINGS USING A CONTROLLED SOURCE IN THE NEAR ZONE
Relevance. The work is aimed at bridging the gap in obtaining data on the upper part of the section during audiomagnetotelluric sounding. At the same time, the problem of uncontrolled displacement of sounding curves due to galvanic distortions introduced by near-surface irregularities is being solve...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | Russian |
| Published: |
Tomsk Polytechnic University
2021-08-01
|
| Series: | Известия Томского политехнического университета: Инжиниринг георесурсов |
| Subjects: | |
| Online Access: | http://izvestiya.tpu.ru/archive/article/view/3316/2536 |
| Summary: | Relevance. The work is aimed at bridging the gap in obtaining data on the upper part of the section during audiomagnetotelluric sounding. At the same time, the problem of uncontrolled displacement of sounding curves due to galvanic distortions introduced by near-surface irregularities is being solved. The main aim of this work is to test the research methodology by the audiomagnetotelluric sounding method together with a controlled source in the near zone to obtain information about the near-field distribution and the introduction of static corrections. Methods. Audiomagnetotelluric soundings were carried out using the receiving and recording equipment OMAR-2 (Institute of Geophysics UB RAS, Yekaterinburg) in the frequency range of 60–16000 Hz. The basic principles of audiomagnetotelluric processing are based on the previously developed method for converting the frequency curves of soundings into geometric curves, taking into account a priori information. For a detailed study of the upper part of the section, two methods were used: vertical electrical sounding and remote induction sounding. The work by the vertical electrical sounding method was carried out with a set of ERA-MAX equipment (ERA, St. Petersburg) according to the standard method. Remote induction soundings were performed with the MFS-8 equipment (Institute of Geophysics UB RAS, Yekaterinburg) at a frequency of 10 kHz according to the previously developed methodology. Results. Experimental and methodological works were carried out, where an electric field generator with galvanic grounding and an induction-type alternating magnetic field emitter act as a controlled source. Comparisons of the results of processing audio magnetotelluric soundings with a natural source of signals and with additional excitation of an artificial field are carried out. It was found that the transformed sections using controlled sources of various types have similar parameters, they are characterized by increased contrast and greater reliability in the selection of local objects. An optimal version of the setup for audiomagnetotelluric measurements with the additional use of an induction field source such as a vertical magnetic dipole is proposed. Conclusions. The studies performed shown that the use of a controlled source of an electromagnetic field in the near zone improves the information content of audiomagnetotelluric soundings and allows obtaining more reliable information about the geological structure of the section due to the introduction of static corrections. |
|---|---|
| ISSN: | 2500-1019 2413-1830 |