Artificial source tensor electromagnetic exploration method with far references

Abstract

The invention provides an artificial source tensor electromagnetic exploration method with far references. The method comprises the following steps of: (1) arranging one or more far reference points while arranging measuring points, and synchronously recording a time variable of current sending of an artificial field source, and electromagnetic fields of the measuring points and the far reference points; (2) constructing a measuring point matrix X and a reference data matrix Xr; (3) utilizing the reference data matrix Xr to solve a natural electromagnetic field source polarized parameter [alpha], calculating a polarized parameter [beta] according to the time variable of current sending of the artificial field source, and then utilizing [alpha] and [beta] and X to solve a corresponding spatial modulus U of the measuring points to a natural field source and a corresponding spatial modulus V to the artificial field source; and (4) utilizing U and V to solve natural field tensor impedance and artificial field tensor impedance of each measuring point. Based on a conventional artificial field electromagnetic method, one or more far reference points are additionally arranged for data collection; and based on unified data equations, the natural field tensor impedance and the artificial field tensor impedance of each measuring point are simultaneously obtained by one time of processing, and earth electrical parameters required by interpretation are obtained.

Description

technical field [0001] The invention relates to an electromagnetic detection method in the field of surveying geophysics, in particular to an artificial source tensor electromagnetic detection method with remote reference. Background technique [0002] In the field of reconnaissance geophysical electromagnetic methods, the natural field source electromagnetic method (Magnetotelluric, MT; Audio-frequency Magnetotelluric, AMT) has a large detection depth and a light acquisition device, but has a low signal-to-noise ratio and weak anti-noise ability; the traditional far-reference magnetotelluric method A far reference point is introduced while observing the natural electromagnetic field in the survey area, and the influence of noise in the survey area is suppressed by using the characteristics that the reference track signal is correlated with the signal of the survey area and the noise is not correlated, and the quality of impedance data is improved to a certain extent; but It...

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Problems solved by technology

[0002] In the field of reconnaissance geophysical electromagnetic methods, the natural field source electromagnetic method (Magnetotelluric, MT; Audio-frequency Magnetotelluric, AMT) has a large detection depth and a light acquisition device, but has a low signal-to-noise ratio and weak anti-noise ability; the traditional far-reference magnetotelluric method A far reference point is introduced while observing the natural electromagnetic field in the survey area, and the influence of noise in the survey area is suppressed by using the characteristics that the reference track signal is correlated with the signal of the survey area and the noise is not correlated, and the quality of impedance data is improved to a certain extent; but It is still difficult to achieve satisfactory results for data distortion in frequency bands with extremely weak natural electromagnetic field signals (such as AMT "dead frequency band" in the range of 5k ~ 1kHz, MT "dead frequency band" near 1Hz)

To solve this problem, Controlled Source Audio-frequency Magnetotelluric (CSAMT) adopts artificial electromagnetic field source as excitation, observes artificial electromagnetic field in a certain observation area, and improves the data signal-to-noise ratio; but effective impedance data needs to be in "Far zone" acquisition, in the "near zone" and "transition zone" of artificial field sources, the impedance data will be distorted and lead to erroneous interpretation results

Although scholars have successively developed a series of processing methods, such as proposing various data correction strategies, the definition and calculation scheme of apparent resistivity in the whole area, etc., and partially extracted the geoelectric information in the "transition area", but for the "near area" "Observational data, still unavailable

In addition, the existing technical solutions split the unified observed electromagnetic field into two independent signals of natural field and artificial field, and develop corresponding method systems; for example, in the natural field source electromagnetic method, the artificial source signal is regarded as correlated noise, In the controlled source audio magnetotelluric method, the natural electromagnetic field signal is regarded as correlated noise, which causes the loss of data information to a certain extent

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