Artificial source frequency domain electromagnetic sounding device and measurement method

Abstract

The invention discloses an artificial source frequency domain electromagnetic sounding device and a measurement method; the device provided by the invention comprises an emitting system and a receiving system; the emitting system can be used for realizing frequency conversion emission according to a measurement demand, the receiving system is a master-slave distributed acquiring system composed of a master station and a plurality of acquiring stations to measure the whole measurement line simultaneously. The measurement method comprises the following steps: roughly measuring the measurement when performing the artificial source frequency domain electromagnetic sounding, processing and imaging a measurement result at field to find a frequency range corresponding to an abnormal object, encrypting a frequency point and performing the detailed survey aiming at an abnormal position, gradually detailing the frequency point distribution until meeting a resolution requirement to the abnormal object; a different-density frequency point distribution measurement method is adopted in the whole measuring frequency band, the frequency point is encrypted only aiming at a target, the resolution capability to the target is improved and the work efficiency is improved. The measurement method not only can be applied to a controllable source audio magnetotelluric method and a frequency electromagnetic sounding method, but also can be spread to a frequency spectrum induced polarization and a complex resistivity method.

Description

Technical field: [0001] The invention relates to a geophysical exploration device and method, in particular to an artificial source frequency domain electromagnetic sounding device and a measurement method. Background technique: [0002] The artificial source frequency domain electromagnetic sounding method is a type of electromagnetic method that achieves the purpose of sounding by changing the frequency according to the corresponding relationship between electromagnetic wave frequency and penetration depth, mainly including controlled source audio frequency magnetotelluric method (CSAMT) and frequency electromagnetic sounding law etc. In this method, a grounded horizontal current source or a vertical magnetic couple source formed by an ungrounded return line is used as an artificial field source to generate a harmonic electromagnetic field, and the response signals of the underground medium to electromagnetic fields of various frequencies are received synchronously in the ...

AI Technical Summary

Problems solved by technology

[0005] Since the longitudinal resolution of electromagnetic sounding in the frequency domain depends on the observed frequency density or ratio, when the frequency increases or decreases in binary mode, the longitudinal resolution is not higher than 29.3%, which cannot meet the requirements of fine exploration

No matter which of the above measurement methods is used for artificial source frequency domain electromagnetic sounding, the surveyor usually designs the frequency range and frequency interval of the measurement according to the electrical conditions of the survey area and the detection depth of the target before the measurement. When the information of the abnormal body is unknown, set the frequency point to a fixed frequency interval. If the frequency interval is set too large, the resolution of the abnormal body will be low. Pole wiring encrypted frequency point measurement is time-consuming and laborious

If the frequency interval is set too densely, although the overall resolution is improved, the field measurement efficiency is low. At the same time, the measurement results of multiple frequencies for an electrically uniform coverage layer are equivalent to interpolation, which wastes measurement time and energy consumption.

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