Four-dimensional geophysical prospecting method based on natural electric field

Abstract

The invention discloses a natural electric field based four-dimensional geophysical prospecting method, which is performed as follows. Prior to acquiring onsite data, a prospecting project has to undergo thorough designs. Detection apparatuses work at the same time on the ground to acquire electric field distribution signals formed on the ground after the penetration into stratigraphic texture of electromagnetic waves received by a plurality of probe pins on each survey line. The electric field distribution signals are stored after real time spectrum refinement and characteristics information identification. A master computer accesses the data from the detection apparatuses and after comprehensive analysis, draws a survey line provided four-dimensional geophysical prospecting sectional view, conducts qualitative and quantitative analysis on survey lines with characteristics information and arrives at conclusions of the prospecting project by the combination of prospecting analyzing results of a plurality of survey lines. In addition to effectively using a frequency domain three-dimensional geophysical prospecting method, the method of the invention introduces a fourth dimension featuring characteristics parameters varying from time. Compared to the prior art, detection apparatuses require smaller storage space, data from synchronizing detection spots are well correlated and strong enough to resist interference; these advantages allow comprehensive qualitative and quantitative analysis on a detected geological body.

Description

technical field [0001] The invention belongs to geophysical detection technology, in particular to a four-dimensional geophysical detection method based on natural electric field. Background technique [0002] The natural electric field method is one of the Magnetotelluric Sounding (MT for short). The MT method is proposed by the Soviet scholar Tikhonov (1950) and the French scholar Cagniard (1953) in the early 1950s to study the earth using natural alternating electromagnetic fields. A geophysical exploration method of electrical structure; because it does not need artificial power supply, low cost, convenient work, not shielded by high-resistance layers, high resolution for low-resistivity layers, and the exploration depth varies with the frequency of the electromagnetic field, shallow It can be tens of meters deep and hundreds of kilometers deep. Therefore, it has been successfully applied in many fields in recent years, which has aroused widespread interest and great att...

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Problems solved by technology

In the actual detection engineering of the existing method, in order to obtain the pole distance and point distance that meet the requirements, it is necessary to frequently move the probe or arrange a large number of probes and detection cables (or connection lines between the probe and the instrument), which have the following deficiencies: ( 1) Low efficiency For an instrument equipped with only 2 probes, it only takes a few seconds to a few minutes to collect the data of a measuring point (depending on the detection depth), but it often takes a few seconds to move the probe and arrange a measuring point. For tens of minutes, for an instrument equipped with multiple probes, each probe needs to arrange a connection line with the instrument while meeting the requirements of pole distance and point distance, which is cumbersome and requires a large amount of engineering; The difference is large. The existing detection methods need to collect data one by one. The starting time of data collection between the measurement points is relatively long, resulting in different time and space conditions when sampling the data of each measurement point, which increases the difficulty of subsequent data analysis and interpretation. (3) Poor data analysis ability Most of the existing detection methods use two-dimensional or three-dimensional methods based on time-domain data analysis, which is difficult to solve complex geological engineering problems

Among the existing natural electric field detection methods, there are few studies on the frequency-domain characteristics of underground geological bodies. Whether a geophysical detection method can be invented to analyze the stratum structure based on the frequency-domain characteristics of underground geological bodies has not yet been resolved by the scientific and technological circles at home and abroad. No relevant research results and product reports

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