Manual field source frequency domain full-gradient electromagnetic measuring method

Abstract

The invention relates to a manual field source frequency domain full-gradient electromagnetic measuring method. The method includes the steps that measuring lines and measuring points are arranged in a measuring area; a manual field source emits electromagnetic waves with different frequencies, and measurement of electromagnetic field signals corresponding to the emission frequencies of all the measuring points in the measuring area is completed through a measuring unit; electromagnetic field gradient signals of the related measuring points are obtained through difference; electromagnetic gradient information of underground media is inverted according to the measured electromagnetic field gradient signals, and accordingly an underground target body can be explored. Compared with the prior art, same noise signals in adjacent measuring point electric field signals are eliminated, the anti-jamming capability of collecting units is enhanced, the signal to noise ratio is improved, the requirement for emission power of the manual field source is lowered, the resolving power higher than that of an electric field is achieved, the boundary of a geologic body can be delineated, spatial distribution details of the geologic body are reflected, the sensitiveness to deep electrical property change is good, field measuring efficiency is improved, construction cost is lowered, and explanatory accuracy to geology abnormity is improved.

Description

Technical field: [0001] The invention relates to a geophysical electromagnetic prospecting method, in particular to an artificial field source frequency-domain electromagnetic gradient measurement method suitable for delineating and identifying the boundary of an underground abnormal body by using an artificial field source in a noise-disturbed survey area environment. Background technique: [0002] Electromagnetic prospecting is a geophysical method that uses the principle of electromagnetic induction to study the distribution of alternating electromagnetic fields excited by natural field sources or artificial field sources in the earth, and studies the electrical properties and geological characteristics of the ground from the observed electromagnetic field distribution. It is widely used in exploration and geological and engineering environmental surveys. Electromagnetic methods are mainly divided into time-domain electromagnetic methods and frequency-domain electromagnet...

AI Technical Summary

Problems solved by technology

This measure is conducive to enhancing the absolute electromagnetic response range of deep geological bodies, which is convenient for receiver detection. However, due to the limitations of field construction conditions and device level, the expansion space for high-power transmission is limited, and the suppression level of noise is limited.

[0004] In addition, when the current artificial source frequency domain electromagnetic method detects the underground structure through the absolute electromagnetic field, the change of the apparent resistivity along the survey line caused by the underground anomaly is gentle and gradual, and the measurement results can only determine the approximate location of the anomaly. Unable to delineate and identify the boundary details of anomalous bodies (including longitudinal interface)

At the same time, this measurement method cannot identify some small anomalies and some secondary fault zones that control oil and gas reservoirs or ore bodies, and is easy to miss, which is difficult to meet the needs of deep fine exploration

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