Method and apparatus for obtaining controllable source audio-frequency magnetotelluric (CSAMT) apparent phase information

Abstract

The invention brings forward a method and apparatus for obtaining controllable source audio magnetotelluric (CSAMT) apparent phase information, and relates to the field of coalfield hydrogeology and geophysics. The method comprises the following steps: obtaining CSAMT electric field component potential difference data; through the potential difference data, obtaining apparent resistivity data; and according to the apparent resistivity data, calculating apparent phase data by use of a ratio. According to the invention, restrictions of a "remote area" are removed, under the condition of lack of magnetic field data, the apparent phase information is obtained by use of electric field single component data, and thus an important reference basis is provided for CSAMT data interpretation.

Description

technical field

[0001] The invention relates to the fields of coalfield hydrogeology and geophysics, in particular to a method and a device for obtaining apparent phase information of a controllable source audio frequency magnetotelluric method. Background technique

[0002] The magnetotelluric method (Magnetotelluric, MT) and the controlled source audio-frequency magnetotelluric method (Controlled source audio-frequency magnetotelluric, CSAMT) are the two most commonly used and most important working methods in the frequency domain electromagnetic method. Among them, the CSAMT method is an artificial source electromagnetic method based on the basic theory of MT in order to overcome the weak signal of natural field sources. In actual field work, CSAMT usually observes a set of orthogonal electric and magnetic field component data, and then calculates the apparent resistivity ρ according to the ratio of the electric and magnetic field component data s , while calculating the...

Examples

Embodiment 1

[0091] The geoelectric model is selected as a K-type geoelectric section, and the geoelectric parameter is ρ 1 =10Ω·m, ρ 2 = ρ 3 =320Ω·m, h 1 = 200m, h 2 = 400m. Emitting source length dL = 1000m, polar distance r = 1200m, MN = 40m. Calculate the CSAMT electric field E according to the following formula x Response data, then follow the formula Calculate the induced voltage data at each frequency point.

[0092] E x = I d L ρ 2 πr 3

[0093] ΔV M N ‾ = E x · M N ‾

[0094] in

[0095] In the formula, I is the current intensity of th...

Embodiment 2

[0107] The survey area is located in Taiyuan City, at the northern end of the Taiyuan Basin. The terrain is piedmont hills, and the ravines are developed in a dendritic distribution, and the terrain is complex. The structure type is a rift basin structure. The survey area is a depression zone in the secondary uplift area, that is, the syncline zone, and there are coal-bearing strata preserved in the syncline zone. The area is generally covered by the Quaternary system, and the loess cover is very thick, most of which are between 300-400m.

[0108] E is achieved by observing the average potential difference between two ground electrodes x The observation of the component adopts the equatorial dipole device: r=2000m, AB=500m, MN=200m, the line distance is 1000m, the point distance is 250m, and the recording point is set at the midpoint of r.

[0109] When conducting electromagnetic frequency sounding, local near-surface electrical inhomogeneities (alluvium, river bed, rock out...

technical field

[0001] The invention relates to the fields of coalfield hydrogeology and geophysics, in particular to a method and a device for obtaining apparent phase information of a controllable source audio frequency magnetotelluric method. Background technique

[0002] The magnetotelluric method (Magnetotelluric, MT) and the controlled source audio-frequency magnetotelluric method (Controlled source audio-frequency magnetotelluric, CSAMT) are the two most commonly used and most important working methods in the frequency domain electromagnetic method. Among them, the CSAMT method is an artificial source electromagnetic method based on the basic theory of MT in order to overcome the weak signal of natural field sources. In actual field work, CSAMT usually observes a set of orthogonal electric and magnetic field component data, and then calculates the apparent resistivity ρ according to the ratio of the electric and magnetic field component data s , while calculating the...

Examples

Embodiment 1

[0091] The geoelectric model is selected as a K-type geoelectric section, and the geoelectric parameter is ρ 1 =10Ω·m, ρ 2 = ρ 3 =320Ω·m, h 1 = 200m, h 2 = 400m. Emitting source length dL = 1000m, polar distance r = 1200m, MN = 40m. Calculate the CSAMT electric field E according to the following formula x Response data, then follow the formula Calculate the induced voltage data at each frequency point.

[0092] E x = I d L ρ 2 πr 3

[0093] ΔV M N ‾ = E x · M N ‾

[0094] in

[0095] In the formula, I is the current intensity of th...

Embodiment 2

[0107] The survey area is located in Taiyuan City, at the northern end of the Taiyuan Basin. The terrain is piedmont hills, and the ravines are developed in a dendritic distribution, and the terrain is complex. The structure type is a rift basin structure. The survey area is a depression zone in the secondary uplift area, that is, the syncline zone, and there are coal-bearing strata preserved in the syncline zone. The area is generally covered by the Quaternary system, and the loess cover is very thick, most of which are between 300-400m.

[0108] E is achieved by observing the average potential difference between two ground electrodes x The observation of the component adopts the equatorial dipole device: r=2000m, AB=500m, MN=200m, the line distance is 1000m, the point distance is 250m, and the recording point is set at the midpoint of r.

[0109] When conducting electromagnetic frequency sounding, local near-surface electrical inhomogeneities (alluvium, river bed, rock out...

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