Method for calculating magnetic permeability, method for calculating magnetic susceptibility, and method for calculating resistivity

Abstract

The application discloses a magnetic permeability calculation method, comprising setting a standard collection point and a mobile collection point; measuring natural electromagnetic fields at the standard collection point and the mobile collection point respectively; calculating wave impedance information of the standard collection point; calculating wave impedance information of the mobile collection point; calculating a magnetic permeability expression of the mobile collection point; calculating magnetic permeability information of the mobile collection point based on plane electromagnetic wave theory, and completing magnetic permeability calculation of a target detection area. The application also discloses a magnetic susceptibility calculation method comprising the magnetic permeability calculation method, and a resistivity calculation method comprising the magnetic permeability calculation method and the magnetic susceptibility calculation method. Through plane electromagnetic wave calculation of the standard collection point and the mobile collection point, the application can not only realize the magnetic permeability calculation method, the magnetic susceptibility calculation and the resistivity calculation of the target detection area at one time, but also has higher reliability and better accuracy.

Description

Technical Field

[0001] This invention belongs to the field of geomagnetic detection, specifically relating to a method for calculating magnetic permeability, a method for calculating magnetic susceptibility, and a method for calculating resistivity. Background Technology

[0002] Plane electromagnetic wave theory is a crucial electromagnetic exploration theory in the field of geophysical exploration. Currently, the main exploration method based on plane electromagnetic wave theory is magnetotellurics. The propagation of natural electromagnetic fields across the Earth can be approximated as quasi-static. Magnetotellurics measures the horizontal electric and magnetic field components of natural electromagnetic waves at the Earth's surface to explore the subsurface medium and utilizes the skin effect to calculate the resistivity parameters of the subsurface medium. At present, magnetotellurics is widely used in the investigation of geological defects in deep-buried tunnels, mineral exploration, and the exploration of deep underground structures.

[0003] Currently, magnetotelluric methods require prior knowledge of the magnetic permeability parameter μ of the target geological body when calculating the resistivity parameter ρ of subsurface media. However, the magnetic permeability parameter μ of the target geological body is difficult to obtain directly. Therefore, in current calculations, researchers widely use the magnetic permeability μ0 in vacuum to replace the magnetic permeability parameter μ of the target geological body. However, this alternative calculation method has the following problems: First, this method can only calculate the resistivity ρ of the target geological body, but cannot calculate the magnetic susceptibility κ of the target geological body; Second, in most cases, the difference between the magnetic permeability parameter μ of the target geological body and the magnetic permeability μ0 in vacuum is very small. However, if the target geological body contains magnetic geological bodies, especially ferromagnetic geological bodies, the difference between the magnetic permeability parameter μ of the target geological body and the magnetic permeability μ0 in vacuum is extremely large. In this case, the reliability and accuracy of this alternative calculation method are poor, and the resistivity parameter ρ of the target geological body cannot be obtained, thus failing to yield correct exploration results. Summary of the Invention

[0004] One of the objectives of this invention is to provide a highly reliable and accurate method for calculating magnetic permeability.

[0005] The second objective of this invention is to provide a method for calculating magnetic susceptibility that includes the aforementioned method for calculating magnetic permeability.

[0006] The third objective of this invention is to provide a resistivity calculation method that includes the aforementioned permeability calculation method and magnetic susceptibility calculation method.

[0007] The permeability calculation method provided by this invention includes the following steps:

[0008] S1. Set up standard acquisition points and mobile acquisition points, and ensure that the standard acquisition points are located in the non-magnetic medium area and the target detection area;

[0009] S2. Measure the natural electromagnetic field at the standard acquisition point and the mobile acquisition point, and obtain the corresponding data information;

[0010] S3. Calculate the wave impedance information of the standard acquisition point based on the data information obtained in step S2;

[0011] S4. Based on the wave impedance information of the standard acquisition point obtained in step S3, calculate the wave impedance information of the moving acquisition point;

[0012] S5. Based on the wave impedance information of the moving acquisition point obtained in step S4, calculate the magnetic permeability expression of the moving acquisition point;

[0013] S6. Based on the obtained wave impedance information and permeability expression of the moving acquisition point, and using the plane electromagnetic wave theory, calculate the permeability information of the moving acquisition point to complete the calculation of the permeability of the target detection area.

[0014] Step S1, which involves setting up a standard acquisition point and a moving acquisition point, and ensuring that the standard acquisition point is located in a non-magnetic medium area and in the target detection area, specifically includes the following steps:

[0015] Set up standard data collection points and mobile data collection points;

[0016] Ensure that the standard sampling point is located in a non-magnetic medium region so that the permeability at the standard sampling point is equal to the permeability in vacuum;

[0017] Set the standard acquisition point in the target detection area so that the standard acquisition point can perform detection in the target detection area.

[0018] Step S2, which involves measuring the natural electromagnetic field at both the standard acquisition point and the mobile acquisition point and acquiring the corresponding data, specifically includes the following steps:

[0019] At the standard sampling point and the mobile sampling point, the horizontal electric field and the horizontal magnetic induction intensity of the natural magnetic field were detected respectively.

[0020] Under quasi-static conditions, the horizontal electric field detected at the standard sampling point is E. ref The horizontal magnetic induction intensity is B ref The horizontal electric field detected by the mobile sampling point is E. meas The horizontal magnetic induction intensity is B meas ;

[0021] At the same time, there exists

[0022] B ref =μ0H ref

[0023] B meas =μmeas H meas

[0024] In the formula, μ0 is the permeability in vacuum; H ref The magnetic field at the standard sampling point; H meas The magnetic field of the moving acquisition point; μ meas The magnetic permeability is at the mobile sampling point.

[0025] Step S3, which involves calculating the wave impedance information of the standard acquisition point based on the data information obtained in step S2, specifically includes the following steps:

[0026] The wave impedance η of the standard acquisition point was calculated. ref for

[0027] Step S4, which involves calculating the wave impedance information of the moving acquisition point based on the wave impedance information of the standard acquisition point obtained in step S3, specifically includes the following steps:

[0028] The wave impedance η of the moving acquisition point at z=0 is calculated using the following formula. meas :

[0029]

[0030] In the formula, η0 is the electromagnetic wave impedance of the air; z is the height, and z = 0 indicates ground surface measurement.

[0031] Step S5, which involves calculating the permeability expression of the moving acquisition point based on the wave impedance information obtained in step S4, specifically includes the following steps:

[0032] The permeability μ of the moving acquisition point at z=0 is calculated using the following formula. meas The expression is

[0033]

[0034] Step S6, which involves calculating the permeability information of the moving acquisition point based on the obtained wave impedance information and permeability expression, using plane electromagnetic wave theory, specifically includes the following steps:

[0035] According to the plane electromagnetic wave theory, there exists Where E x H represents the horizontal electric field intensity in the earth's medium. y The vertical magnetic field strength in the Earth's medium. η is the intensity of the natural electromagnetic wave, η1 is the electromagnetic wave impedance of the underground medium, k is the beam, and i is the imaginary unit.

[0036] Based on the obtained wave impedance η of the moving acquisition pointmeas and permeability μ meas The expression is used to calculate the magnetic permeability μ of the moving acquisition point. meas for

[0037] The present invention also provides a method for calculating magnetic susceptibility that includes the aforementioned method for calculating magnetic permeability, further comprising the following steps:

[0038] S7. Based on the permeability of the moving acquisition point obtained in step S6, calculate the magnetization of the moving acquisition point to complete the calculation of the magnetization of the target detection area.

[0039] Step S7, which involves calculating the magnetization of the moving acquisition point based on the permeability obtained in step S6, specifically includes the following steps:

[0040] The calculated magnetic susceptibility κ at the moving acquisition point is:

[0041] The present invention also provides a resistivity calculation method that includes the aforementioned permeability calculation method and magnetic susceptibility calculation method, further comprising the following steps:

[0042] S8. Based on the magnetic susceptibility at the moving acquisition point obtained in step S7, calculate the resistivity of the moving acquisition point to complete the calculation of the resistivity of the target detection area.

[0043] The permeability calculation method, magnetic susceptibility calculation method, and resistivity calculation method provided by this invention, through the calculation of plane electromagnetic waves at standard acquisition points and moving acquisition points, can not only realize the calculation of permeability, magnetic susceptibility, and resistivity of the target detection area in one go, but also has higher reliability and better accuracy. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the method flow for calculating the magnetic permeability of the present invention.

[0045] Figure 2 This is a schematic diagram of the method flow for calculating the magnetic susceptibility of the present invention.

[0046] Figure 3 This is a schematic diagram of the resistivity calculation method of the present invention. Detailed Implementation

[0047] like Figure 1 The diagram shown illustrates the process flow of the permeability calculation method of the present invention. This permeability calculation method provided by the present invention includes the following steps:

[0048] S1. Set up standard acquisition points and mobile acquisition points, ensuring that the standard acquisition points are located in a non-magnetic medium area and within the target detection area; specifically including the following steps:

[0049] Set up standard data collection points and mobile data collection points;

[0050] Ensure that the standard sampling point is located in a non-magnetic medium region so that the permeability at the standard sampling point is equal to the permeability in vacuum;

[0051] Set the standard acquisition points in the target detection area so that the standard acquisition points can perform detection in the target detection area;

[0052] S2. Measure the natural electromagnetic field at both the standard acquisition point and the mobile acquisition point, and obtain the corresponding data; specifically, this includes the following steps:

[0053] At the standard sampling point and the mobile sampling point, the horizontal electric field and the horizontal magnetic induction intensity of the natural magnetic field were detected respectively.

[0054] Under quasi-static conditions, the horizontal electric field detected at the standard sampling point is E. ref The horizontal magnetic induction intensity is B ref The horizontal electric field detected by the mobile sampling point is E. meas The horizontal magnetic induction intensity is B meas ;

[0055] At the same time, there exists

[0056] B ref =μ0H ref

[0057] B meas =μ meas H meas

[0058] In the formula, μ0 is the permeability in vacuum; H ref The magnetic field at the standard sampling point; H meas The magnetic field of the moving acquisition point; μ meas The magnetic permeability at the moving data acquisition point;

[0059] S3. Based on the data obtained in step S2, calculate the wave impedance information of the standard acquisition point; specifically including the following steps:

[0060] Based on the condition of a non-magnetic medium, since only the magnetic induction intensity B can be collected in actual measurements... ref Unable to collect magnetic field strength H ref Therefore, the wave impedance η at the standard acquisition point is calculated. ref for

[0061] S4. Based on the wave impedance information of the standard acquisition point obtained in step S3, calculate the wave impedance information of the moving acquisition point; specifically including the following steps:

[0062] The magnetic induction intensity E collected by the mobile acquisition station meas Magnetic induction intensity E collected by the standard acquisition station ref The ratio is calculated, and the following formula is obtained, which is used to calculate the wave impedance η of the moving acquisition point at z=0. meas :

[0063]

[0064] In the formula, η0 is the electromagnetic wave impedance of the air; z is the height, and z = 0 indicates ground surface measurement;

[0065] S5. Based on the wave impedance information of the moving acquisition point obtained in step S4, calculate the permeability expression of the moving acquisition point; specifically including the following steps:

[0066] The magnetic induction intensity B collected by the mobile data acquisition station meas Magnetic induction intensity B collected by the standard acquisition station ref The ratio is calculated, and the following formula is obtained, which is used to calculate the permeability μ of the moving acquisition point at z=0. meas The expression is

[0067] S6. Based on the obtained wave impedance information and permeability expression of the moving acquisition point, and using plane electromagnetic wave theory, calculate the permeability information of the moving acquisition point to complete the permeability calculation of the target detection area; specifically including the following steps:

[0068] According to the plane electromagnetic wave theory, there exists Where E x H represents the horizontal electric field intensity in the earth's medium. y The vertical magnetic field strength in the Earth's medium. η is the intensity of the natural electromagnetic wave, η1 is the electromagnetic wave impedance of the underground medium, k is the beam, and i is the imaginary unit.

[0069] Based on the obtained wave impedance η of the moving acquisition point meas and permeability μ meas The expression is used to calculate the magnetic permeability μ of the moving acquisition point. meas for

[0070] like Figure 2 The diagram shown is a flowchart of the magnetic permeability calculation method of the present invention: The magnetic susceptibility calculation method disclosed in this invention, which includes the aforementioned magnetic permeability calculation method, includes the following steps:

[0071] S1. Set up standard acquisition points and mobile acquisition points, and ensure that the standard acquisition points are located in the non-magnetic medium area and the target detection area;

[0072] S2. Measure the natural electromagnetic field at the standard acquisition point and the mobile acquisition point, and obtain the corresponding data information;

[0073] S3. Calculate the wave impedance information of the standard acquisition point based on the data information obtained in step S2;

[0074] S4. Based on the wave impedance information of the standard acquisition point obtained in step S3, calculate the wave impedance information of the moving acquisition point;

[0075] S5. Based on the wave impedance information of the moving acquisition point obtained in step S4, calculate the magnetic permeability expression of the moving acquisition point;

[0076] S6. Based on the obtained wave impedance information and permeability expression of the moving acquisition point, and based on the plane electromagnetic wave theory, calculate the permeability information of the moving acquisition point to complete the calculation of the permeability of the target detection area;

[0077] S7. Based on the permeability of the moving acquisition point obtained in step S6, calculate the magnetic susceptibility at the moving acquisition point to complete the calculation of the magnetic susceptibility of the target detection area; specifically including the following steps:

[0078] The calculated magnetic susceptibility κ at the moving acquisition point is:

[0079] like Figure 3 The diagram shown is a flowchart of the resistivity calculation method of the present invention: The resistivity calculation method disclosed in this invention, which includes the permeability calculation method and the magnetic susceptibility calculation method, includes the following steps:

[0080] S1. Set up standard acquisition points and mobile acquisition points, and ensure that the standard acquisition points are located in the non-magnetic medium area and the target detection area;

[0081] S2. Measure the natural electromagnetic field at the standard acquisition point and the mobile acquisition point, and obtain the corresponding data information;

[0082] S3. Calculate the wave impedance information of the standard acquisition point based on the data information obtained in step S2;

[0083] S4. Based on the wave impedance information of the standard acquisition point obtained in step S3, calculate the wave impedance information of the moving acquisition point;

[0084] S5. Based on the wave impedance information of the moving acquisition point obtained in step S4, calculate the magnetic permeability expression of the moving acquisition point;

[0085] S6. Based on the obtained wave impedance information and permeability expression of the moving acquisition point, and based on the plane electromagnetic wave theory, calculate the permeability information of the moving acquisition point to complete the calculation of the permeability of the target detection area;

[0086] S7. Based on the permeability of the moving acquisition point obtained in step S6, calculate the magnetization of the moving acquisition point to complete the calculation of the magnetization of the target detection area;

[0087] S8. Based on the magnetic susceptibility at the moving acquisition point obtained in step S7, calculate the resistivity of the moving acquisition point to complete the calculation of the resistivity of the target detection area.

Claims

1. A method for calculating magnetic permeability, comprising the following steps: S1. Set up a standard acquisition point and a moving acquisition point, and ensure that the standard acquisition point is located in a non-magnetic medium area and the moving acquisition point is located in the target detection area; S2. Measure the natural electromagnetic field at the standard acquisition point and the mobile acquisition point, and obtain the corresponding data information; S3. Based on the data obtained in step S2, calculate the wave impedance information of the standard acquisition point; S4. Based on the wave impedance information of the standard acquisition point obtained in step S3, the wave impedance information of the moving acquisition point is calculated based on the plane electromagnetic wave theory. S5. Based on the wave impedance information of the moving acquisition point obtained in step S4, the magnetic permeability expression of the moving acquisition point is calculated based on the plane electromagnetic wave theory. S6. Based on the obtained wave impedance information and permeability expression of the moving acquisition point, calculate the permeability information of the moving acquisition point and complete the permeability calculation of the target detection area.

2. The method for calculating magnetic permeability according to claim 1, characterized in that... Step S1, which involves setting up a standard acquisition point and a moving acquisition point, and ensuring that the standard acquisition point is located in a non-magnetic medium area and the moving acquisition point is located in the target detection area, specifically includes the following steps: Set up standard data collection points and mobile data collection points; Ensure that the standard sampling point is located in a non-magnetic medium region so that the permeability at the standard sampling point is equal to the permeability in vacuum; Set the mobile acquisition point in the target detection area so that the mobile acquisition point can perform detection in the target detection area.

3. The method for calculating magnetic permeability according to claim 2, characterized in that... Step S2, which involves measuring the natural electromagnetic field at both the standard acquisition point and the mobile acquisition point and acquiring the corresponding data, specifically includes the following steps: At the standard sampling point and the mobile sampling point, the horizontal electric field and the horizontal magnetic induction intensity of the natural magnetic field were detected respectively. Under quasi-static conditions, the horizontal electric field detected at the standard sampling point is: The horizontal magnetic induction intensity is ; The horizontal electric field detected by the mobile sampling point is The horizontal magnetic induction intensity is ; At the same time, there exists In the formula ρ is the magnetic permeability in vacuum; The magnetic field of the standard acquisition point; The magnetic field of the moving data acquisition point; The magnetic permeability is at the mobile sampling point.

4. The method for calculating magnetic permeability according to claim 3, characterized in that... Step S3, which involves calculating the wave impedance information of the standard acquisition point based on the data information obtained in step S2, specifically includes the following steps: The wave impedance of the standard acquisition point was calculated. for .

5. The method for calculating magnetic permeability according to claim 4, characterized in that... Step S4, which involves calculating the wave impedance information of the moving acquisition point based on the wave impedance information of the standard acquisition point obtained in step S3 and the plane electromagnetic wave theory, specifically includes the following steps: The following formula is used to calculate the result. Wave impedance of the moving acquisition point : In the formula The electromagnetic wave impedance of air; For height, It refers to surface measurements.

6. The method for calculating magnetic permeability according to claim 5, characterized in that... Step S5, which involves calculating the permeability expression of the moving acquisition point based on the wave impedance information obtained in step S4 and plane electromagnetic wave theory, specifically includes the following steps: The following formula is used to calculate the result. magnetic permeability of the moving acquisition point The expression is 。 7. The method for calculating magnetic permeability according to claim 6, characterized in that... Step S6, which involves calculating the permeability information of the moving acquisition point based on the obtained wave impedance information and permeability expression, specifically includes the following steps: Based on the wave impedance of the moving acquisition point and permeability The expression is used to calculate the magnetic permeability of the moving acquisition point. for .

8. A method for calculating magnetic susceptibility that includes the method for calculating magnetic permeability according to any one of claims 1 to 7, characterized in that... It also includes the following steps: S7. Based on the permeability of the moving acquisition point obtained in step S6, calculate the magnetization at the moving acquisition point to complete the calculation of the magnetization of the target detection area.

9. The method for calculating magnetic susceptibility according to claim 8, characterized in that... Step S7, which involves calculating the magnetic susceptibility at the moving acquisition point based on the permeability obtained in step S6, specifically includes the following steps: The magnetic susceptibility at the moving acquisition point was calculated. for .

10. A resistivity calculation method incorporating the magnetic susceptibility calculation method according to claim 8 or 9, characterized in that... It also includes the following steps: S8. Based on the magnetic susceptibility at the moving acquisition point obtained in step S7, calculate the resistivity of the moving acquisition point to complete the calculation of the resistivity of the target detection area.

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