Layered medium detection method based on electromagnetic field, storage medium and electronic equipment

Abstract

The invention provides a layered medium detection method based on an electromagnetic field, a storage medium and electronic equipment. The method comprises the steps that electric field data and magnetic field data of a to-be-detected target are acquired; determining the impedance of the to-be-measured target and determining an apparent resistivity curve of the to-be-measured target according to the impedance of the to-be-measured target; based on the apparent resistivity, determining a resistivity value of a current first-layer medium of the to-be-measured target; based on the apparent resistivity curve of the to-be-measured target and the resistivity value of the current first-layer medium, determining the thickness of the current first-layer medium of the to-be-measured target; and performing layer-by-layer impedance stripping on the to-be-measured target based on the resistivity value and the thickness of the current first layer of medium, and determining the resistivity value and the thickness of each layer of medium of the to-be-measured target. According to the scheme, each layer of medium of the detection target is stripped layer by layer, the thickness and the resistivity of each layer of medium are effectively calculated, layered medium detection of the detection target is achieved, and the method has the advantages of being non-contact, free of pollution, low in cost, easy to operate, high in speed, free of coupling and the like.

Description

Technical Field

[0001] The present application relates to the technical field of layered medium detection. Specifically, it relates to a method for detecting layered media based on electromagnetic fields, a storage medium, and an electronic device. Background Art

[0002] For the detection of layered media (such as the detection of the earth's layered media, the detection of metal coatings, etc.), there are currently traditional visual inspections, chemical analyses, etc., as well as non-destructive detection techniques that utilize the characteristics of sound, light, force, electromagnetic, etc. to detect materials and structural components without damaging the applicability and usability of the detection target. Currently, ray, ultrasonic, magnetic particle, penetrant, and eddy current are five commonly used detection techniques with wide applications.

[0003] Electromagnetic detection technology has the advantages of non-contact, pollution-free, low cost, simple operation, etc., and is widely used to detect the electromagnetic parameter information of media at different depths. Since in layered media, impedance and apparent resistivity data contain electromagnetic field information, the present application fully explores the information contained in the apparent resistivity and intends to provide a more advantageous layered medium detection scheme. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a method for detecting layered media based on electromagnetic fields, a storage medium, and an electronic device. By fully exploring the information in the data obtained by electromagnetic detection technology, the "stripping impedance" method is designed. By gradually stripping each layer of the medium of the detection target, the thickness and resistivity of each layer of the medium can be effectively calculated, realizing the detection of the layered media of the detection target, and having the advantages of non-contact, pollution-free, low cost, simple operation, high speed, and no need for coupling.

[0005] To achieve the above purpose, the embodiments of the present application are implemented as follows:

[0006] In a first aspect, the embodiments of the present application provide a method for detecting layered media based on electromagnetic fields, including: obtaining the electric field data and magnetic field data of the target to be measured; determining the impedance of the target to be measured based on the electric field data and magnetic field data of the target to be measured; determining the apparent resistivity curve of the target to be measured based on the electric field data and magnetic field data of the target to be measured; determining the resistivity value of the current first layer of the medium of the target to be measured based on the apparent resistivity; determining the thickness of the current first layer of the medium of the target to be measured based on the apparent resistivity curve of the target to be measured and the resistivity value of the current first layer of the medium; and performing layer-by-layer "impedance stripping" on the target to be measured based on the resistivity value and thickness of the current first layer of the medium to determine the resistivity value and thickness of each layer of the medium of the target to be measured.

[0007] In combination with the first aspect, in the first possible implementation manner of the first aspect, determining the impedance of the target to be measured based on the electric field data and magnetic field data of the target to be measured includes:

[0008] The impedance is calculated using the following formula:

[0009]

[0010] Or

[0011]

[0012] Where Z is the impedance of the target to be measured, E is the electric field, E x is the horizontal electric field component of the electric field E in the x direction, E y is the horizontal electric field component of the electric field E in the y direction, H is the magnetic field, H x is the horizontal magnetic field component of the magnetic field H in the x direction, H y is the horizontal magnetic field component of the magnetic field H in the y direction.

[0013] Combined with the first aspect, in the second possible implementation manner of the first aspect, if the frequency is higher than 10 4 Hz, based on the electric field data and magnetic field data of the target to be measured, the apparent resistivity curve of the target to be measured is determined, including: calculating the apparent resistivity using the following formula:

[0014]

[0015] Where ρ s is the apparent resistivity, ω is the angular frequency, μ0 is the magnetic permeability of vacuum, Z is the impedance, and imag represents taking the imaginary part.

[0016] Combined with the first aspect, in the third possible implementation manner of the first aspect, if the frequency is not higher than 10 4 Hz, based on the electric field data and magnetic field data of the target to be measured, the apparent resistivity curve of the target to be measured is determined, including:

[0017] Calculating the apparent resistivity using the following formula:

[0018]

[0019] Where ρ s is the apparent resistivity, ω is the angular frequency, μ0 is the magnetic permeability of vacuum, Z is the impedance, and imag represents taking the imaginary part;

[0020] Alternatively, calculating the apparent resistivity using the following formula:

[0021]

[0022] Where μ0 is the magnetic permeability of vacuum, ω is the angular frequency, and Z is the impedance;

[0023] Based on the calculated apparent resistivity, the apparent resistivity curve of the target to be measured is determined.

[0024] In combination with the first aspect, in the fourth possible implementation manner of the first aspect, based on the apparent resistivity, determining the resistivity value of the current first-layer medium of the target to be measured includes:

[0025] Judging whether the difference between the top three apparent resistivity data with the highest frequencies in the current apparent resistivity is within 1‰;

[0026] If so, determining the apparent resistivity at the highest frequency in the apparent resistivity as the resistivity value of the current first-layer medium of the target to be measured;

[0027] If not, expanding the detection frequency range, adjusting the highest frequency of the detection frequency to 10 times the original, updating the electric field data and magnetic field data of the target to be measured, recalculating the impedance of the target to be measured, determining a new apparent resistivity curve, and then continuing to judge until the resistivity value of the current first-layer medium of the target to be measured is determined.

[0028] In combination with the first aspect, in the fifth possible implementation manner of the first aspect, based on the apparent resistivity curve of the target to be measured and the resistivity value of the current first-layer medium, determining the thickness of the current first-layer medium of the target to be measured includes: determining the resistivity value of the current first-layer medium of the target to be measured and the target point frequency of the apparent resistivity curve; calculating the thickness of the current first-layer medium of the target to be measured using the following formula:

[0029]

[0030] where h m is the thickness of the current first-layer medium of the target to be measured, μ0 is the magnetic permeability of vacuum, f c is the target point frequency, and σ m is the resistivity value of the current first-layer medium of the target to be measured.

[0031] In combination with the fifth possible implementation manner of the first aspect, in the sixth possible implementation manner of the first aspect, based on the resistivity value and thickness of the current first-layer medium, performing layer-by-layer "impedance stripping" on the target to be measured to determine the resistivity value and thickness of each layer of the target to be measured includes:

[0032] S1: Using all the calculated resistivity values and thicknesses of the current first-layer medium as known conditions, performing impedance stripping to obtain the impedance of the remaining part of the target to be measured;

[0033] S2: Determining the apparent resistivity curve of the remaining part of the target to be measured;

[0034] S3: Based on the apparent resistivity, determining the resistivity value of the current first-layer medium of the remaining part of the target to be measured;

[0035] S4: Determine the thickness of the current first-layer medium of the remaining part of the object to be measured based on the apparent resistivity curve of the remaining part of the object to be measured and the resistivity value of the current first-layer medium.

[0036] S5: Loop through steps S1 to S4 until the resistivity values and thicknesses of each layer of the medium of the object to be measured are solved.

[0037] Combined with the sixth possible implementation manner of the first aspect, in the seventh possible implementation manner of the first aspect,

[0038] In S1: The impedance of the remaining part of the object to be measured satisfies:

[0039]

[0040] where Z m is the top surface impedance of the m-th layer in the object to be measured, Z m+1 is the bottom surface impedance of the m-th layer in the object to be measured and is also the top surface impedance of the (m + 1)-th layer in the object to be measured, m ∈ [1, N], N is the total number of layered media of the object to be measured, N ≥ 2; Z 0m is the characteristic impedance of the m-th layer, k m is the complex wave number of the m-th layer, h m is the thickness of the m-th layer.

[0041] Second aspect, an embodiment of the present application provides a storage medium installed in a device, including a stored program. When the program runs, it controls the device where the storage medium is located to execute the electromagnetic field-based layered medium detection method described in any one of the first aspect or the possible implementation manners of the first aspect.

[0042] Third aspect, an embodiment of the present application provides an electronic device, including a memory and a processor. The memory is used to store information including program instructions, and the processor is used to control the execution of the program instructions. When the program instructions are loaded and executed by the processor, the steps of the electromagnetic field-based layered medium detection method described in any one of the first aspect or the possible implementation manners of the first aspect are implemented.

[0043] Beneficial effects:

[0044] 1. This solution determines the impedance and apparent resistivity curve of the target to be measured by obtaining the electric field data and magnetic field data of the target to be measured; by mining the information in the apparent resistivity, the resistivity value of the current first layer of the target to be measured is determined, and further the thickness of the current first layer of the target to be measured is calculated. Then, based on the resistivity value and thickness of the current first layer of the medium, the "impedance stripping" of the target to be measured is carried out layer by layer, and accordingly the resistivity value and thickness of each layer of the target to be measured are determined. By fully mining the information in the data obtained by electromagnetic detection technology, the "stripping impedance" method is designed. By stripping each layer of the medium of the detection target layer by layer, the thickness and resistivity of each layer of the medium are effectively calculated, realizing the layered medium detection of the detection target, which has the advantages of non-contact, pollution-free, low cost, simple operation, fast speed, and no need for coupling.

[0045] 2. According to the characteristics of different scenarios, for example, in the field of geophysical electromagnetic exploration, since the frequency is relatively low (generally not exceeding 10 4 Hz), the displacement current can be ignored, and the value of the apparent resistivity of the homogeneous half-space model is equal to the resistivity value of the half-space. Therefore, is used to calculate the apparent resistivity; for high-frequency scenarios (exceeding 10 4 Hz), such as the detection of metal coatings, the displacement current cannot be ignored, and a new definition of apparent resistivity is designed applicable to the full frequency band. For a homogeneous half-space medium, its value is the resistivity value of the homogeneous half-space (for media such as metals, because their resistivity is small, the reciprocal of the apparent resistivity can also be taken and the apparent conductivity can be used for calculation). This enables this solution to be applied to a wider range of layered medium detection scenarios.

[0046] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0048] Figure 1 It is a schematic diagram of a layered medium.

[0049] Figure 2 It is a flowchart of a layered medium detection method based on electromagnetic fields.

[0050] Figure 3Schematic diagram of the apparent resistivity curve of a three-layered medium model.

[0051] Figure 4 Flow chart for performing "impedance stripping" layer by layer on the target to be measured.

[0052] Figure 5 Schematic diagram of the apparent resistivity curve of the remaining part after performing one-layer "impedance stripping" on the three-layered medium model. Specific implementation manners

[0053] Next, the technical solutions in the embodiments of the present application will be described with reference to the accompanying drawings in the embodiments of the present application.

[0054] For the convenience of understanding this solution, in this embodiment, the theoretical basis of the layered medium detection method based on electromagnetic fields in the present application is first deduced.

[0055] Medium: In this embodiment, it refers to the target to be detected, such as metal layered medium, earth layered medium, ice layered medium, etc.

[0056] Cagniard apparent resistivity: The Cagniard apparent resistivity was proposed by L. Cagniard in 1953 and is used in magnetotelluric sounding. It calculates the resistivity by measuring the impedance at different frequencies, thereby reflecting the electrical structure at different depths. The key points here are the characteristics of impedance as a function of the earth's interior electrical properties and the relationship between frequency and detection depth.

[0057] All macroscopic electromagnetic phenomena satisfy Maxwell's equations, and their differential forms are as follows:

[0058]

[0059] Among them, is the Hamiltonian operator, which is in the rectangular coordinate system. E is the electric field strength, B is the magnetic induction intensity, D is the electric displacement, H is the magnetic field strength, J is the current density, ρ is the free charge density, i is the imaginary part, and ω is the angular frequency.

[0060] The three constitutive relations are:

[0061] D = εE, (5)

[0062] B = μH, (6)

[0063]

[0064] In the formula, the parameters ε, μ, and σ are the permittivity, permeability, and conductivity respectively, indicating that the conductivity is a tensor.

[0065] As Figure 1 shown,Figure 1 Schematic diagram of a layered medium

[0066] It is assumed that the layered medium consists of N horizontally layered media, and the conductivities of each layer are respectively:

[0067] σ1, σ2, …, σ N , (8)

[0068] The thicknesses are respectively:

[0069] h1, h2, …, h N , (9)

[0070] Then, by using the relationship between the impedance values at two different depths in the same layer and the condition of impedance continuity at the interface, the recurrence formula of the surface impedance (understood as the impedance of the top surface of the first-layer medium) can be derived.

[0071] According to Maxwell's equations, taking the time-harmonic factor as e -iωt , in any layer of the medium, we can obtain:

[0072]

[0073] In the formula, E x is the horizontal electric field component of the electric field E in the x direction, k m is the complex wave number of the m-th layer, m ∈ [1, N], and it satisfies:

[0074]

[0075] Considering the full frequency band here, the displacement current term is retained, μ0 is the vacuum permeability, and σ m is the conductivity of the m-th layer.

[0076] Then, the general solution of equation (10) is:

[0077]

[0078] Among them, z represents the depth, and A and B generally refer to constants.

[0079] Using the relationship between E x and H y , we can obtain:

[0080]

[0081] The impedance expression is:

[0082]

[0083] Taking as the characteristic impedance of the m-th layer, and assuming that the depth of the top surface of the m-th layer is z m, the bottom depth is z m+1 , then the impedances at these depths in the m-th layer can be respectively expressed as:

[0084]

[0085] By combining Equation (15) and Equation (16), we can obtain:

[0086]

[0087] Thus, we can get:

[0088]

[0089] Let z m+1 -z m = h m , that is, the thickness of the m-th layer. Substituting it into Equation (18), we can get:

[0090]

[0091] It can also be written as:

[0092]

[0093] Let:

[0094]

[0095] According to Equation (20), we can inversely deduce to get:

[0096]

[0097] The Cagniard apparent resistivity is a parameter commonly used in magnetotelluric sounding (MT) to describe the resistivity distribution of underground media. It is calculated by measuring the horizontal electric field component (E x , E y ) and the vertical magnetic field component (H z ), and the formula is:

[0098]

[0099] Among them, μ0 is the magnetic permeability of vacuum, ω is the angular frequency, and Z is the impedance, satisfying:

[0100]

[0101] Among them, E is the electric field, E x is the horizontal electric field component of the electric field E in the x direction, E y is the horizontal electric field component of the electric field E in the y direction, and H is the magnetic field, Hx is the horizontal magnetic field component of the magnetic field H in the x direction, H y is the horizontal magnetic field component of the magnetic field H in the y direction.

[0102] The apparent resistivity defined by the above formula (23) is applicable to the field of geophysical electromagnetic exploration (displacement current can be ignored), and the value of the apparent resistivity of the homogeneous half-space model is equal to the resistivity value of the half-space. However, it is no longer applicable at high frequencies (when displacement current cannot be ignored). Accordingly, for the full frequency band (low frequency to high frequency), a new definition of apparent resistivity is proposed in this embodiment as follows:

[0103]

[0104] This definition is applicable to the full frequency band. For a homogeneous half-space medium, its value is the resistivity value of the homogeneous half-space. For a medium such as metal, because its resistivity is small, the reciprocal of the apparent resistivity can also be taken to use the apparent conductivity.

[0105] The above is the derivation process of the theoretical basis of this solution (derivation is carried out taking a plane wave as an example), which is a derivation scheme based on resistivity. Based on the same concept, this derivation process can also be applied to a derivation scheme based on conductivity (reciprocal of resistivity). Therefore, the protection scope of the inventive concept of the present invention should include the scheme based on resistivity and the scheme based on conductivity. In this embodiment, the resistivity is taken as an example for introduction, and the conductivity scheme is similar (with slight differences in formula form), which should not be regarded as a limitation to this application.

[0106] Accordingly, this embodiment provides a method for detecting layered media based on electromagnetic fields, which is applied to electronic devices (such as computers, servers, etc.). Please refer to Figure 2 , Figure 2 is the flowchart of the method for detecting layered media based on electromagnetic fields.

[0107] In this embodiment, the method for detecting layered media based on electromagnetic fields may include step S10, step S20, step S30, step S40, step S50, and step S60.

[0108] When detecting layered media (the purpose of detection is to determine the resistivity value and thickness of each layer of layered media of the target to be measured), first, the electronic device can execute step S10.

[0109] Step S10: Obtain the electric field data and magnetic field data of the target to be measured.

[0110] In this embodiment, the electronic device can obtain the electric field data and magnetic field data of the target to be measured. The electric field data includes the electric field E, and the magnetic field data includes the magnetic field H.

[0111] After obtaining the electric field data and magnetic field data of the target to be measured, the electronic device can execute step S20.

[0112] Step S20: Based on the electric field data and magnetic field data of the target to be measured, determine the impedance of the target to be measured.

[0113] In this embodiment, since the theoretical derivation process has been introduced above, it will not be elaborated here. To determine the impedance of the target to be measured, mainly use formula (24), that is, calculate the impedance using the following formula:

[0114]

[0115] Or

[0116]

[0117] Among them, Z is the impedance of the target to be measured, E is the electric field, E x is the horizontal electric field component of the electric field E in the x direction, E y is the horizontal electric field component of the electric field E in the y direction, H is the magnetic field, H x is the horizontal magnetic field component of the magnetic field H in the x direction, H y is the horizontal magnetic field component of the magnetic field H in the y direction.

[0118] After that, the electronic device can execute step S30.

[0119] Step S30: Based on the electric field data and magnetic field data of the target to be measured, determine the apparent resistivity curve of the target to be measured.

[0120] In this embodiment, the electronic device can determine the apparent resistivity according to the detection scenario by adopting the corresponding scheme. Refer to formulas (23)-(25) above.

[0121] If the frequency is higher than 10 4 Hz (such as in the scenario of coating detection), the displacement current cannot be ignored. Then, adopt the apparent resistivity calculation scheme of formula (25), that is:

[0122] Calculate the apparent resistivity using the following formula:

[0123]

[0124] Among them, ρ s is the apparent resistivity, ω is the angular frequency, μ0 is the vacuum permeability, Z is the impedance, and imag represents taking the imaginary part.

[0125] If the frequency does not exceed 10 4 Hz, either the apparent resistivity can be calculated using formula (28), or the apparent resistivity calculation scheme of formula (23) can be adopted, that is:

[0126] The apparent resistivity is calculated using the following formula:

[0127]

[0128] where ρ s is the apparent resistivity, ω is the angular frequency, μ0 is the magnetic permeability of vacuum, and Z is the impedance.

[0129] Based on the calculated apparent resistivity, the apparent resistivity curve of the target to be measured can be determined (generally arranged from high to low in frequency to form the apparent resistivity curve).

[0130] For ease of understanding, taking the three-layered medium model (i.e., the model shown Figure 1 as an example, the model parameters are: the resistivity of the three layers of media is 100 Ω·m, 10 Ω·m, and 200 Ω·m, and the thicknesses of the three layers of media are 1000 m, 800 m, and a uniform half-space respectively. It should be noted that before detection, it is not necessary to know the number of layers of the layered media of the target to be measured, nor the resistivity and thickness of each layer of layered media. The purpose of detection is to determine the resistivity and thickness of each layer of layered media. And the determined apparent resistivity curve is as shown Figure 3 in the figure.

[0131] After obtaining the apparent resistivity curve of the target to be measured, the electronic device can execute step S40.

[0132] Step S40: Based on the apparent resistivity, determine the resistivity value of the current first layer of the target to be measured.

[0133] Considering that when the frequency is high enough, the value of the apparent resistivity curve is the resistivity value of the first layer of the medium. According to the apparent resistivity data, the resistivity value of the first layer of the medium can be directly obtained. In this embodiment, the electronic device can determine whether the difference between the first three apparent resistivity data with the highest frequency in the current apparent resistivity is within 1‰.

[0134] If the condition is satisfied, determine the apparent resistivity at the highest frequency in the apparent resistivity as the resistivity value of the current first layer of the target to be measured.

[0135] Otherwise, expand the detection frequency range, adjust the highest frequency of the detection frequency to 10 times the original (for example, if the highest frequency at the beginning of detection starts to gradually decrease from 100 Hz, then now adjust it once, expand the highest frequency by 10 times, and start to gradually decrease from 1000 Hz, while the lowest frequency remains unchanged, expanding the detection frequency range), update the electric field data and magnetic field data of the target to be measured, recalculate the impedance of the target to be measured, determine a new apparent resistivity curve, and then continue to judge until the resistivity value of the current first layer of the target to be measured is determined.

[0136] Continuing with the above example, the resistivity value ρ1 of the first-layer medium is 99.9992753161281 Ω·m.

[0137] After determining the resistivity value, the electronic device can execute step S50.

[0138] Step S50: Based on the apparent resistivity curve of the target to be measured and the resistivity value of the current first-layer medium, determine the thickness of the current first-layer medium of the target to be measured.

[0139] In this embodiment, the electronic device can determine the target point frequency f of the resistivity value of the current first-layer medium of the target to be measured and the apparent resistivity curve c , and then calculate the thickness of the current first-layer medium of the target to be measured using the following formula:

[0140]

[0141] where h m is the thickness of the current first-layer medium of the target to be measured, μ0 is the magnetic permeability of vacuum, f c is the target point frequency, and σ m is the resistivity value of the current first-layer medium of the target to be measured.

[0142] It should be noted that formula (30) here is from the patent document of the applicant: Method for Detecting Seawater Depth Based on Electromagnetic Field, Storage Medium and Electronic Device (Patent Application No. 2024101143877). Its principle and derivation process are similar (although the scenarios are different, this patent document is for seawater depth detection, and this solution is for layered medium thickness detection, but when determining the thickness, the method idea and formula derivation are the same. You can refer to this document, but for the target point frequency, the first target point frequency is used in this article, Figure 3 at the position of "*" in m ). Here, the conclusion is directly cited without further elaboration. Accordingly, based on determining the resistivity σ c of the current first-layer medium and the target point frequency f m , the thickness h

[0143] of the current first-layer medium can be calculated. Figure 3 Continuing with the previous example, locate the point where the apparent resistivity curve and the first-layer resistivity value ( Figure 3 the half space line in c ) start to separate from high frequency to low frequency, such as the * point in= 140.420857594656 Hz, and then substitute it into formula (30) to calculate the thickness, and the thickness h1 of the first-layer laminated medium is obtained as 1000.72300482668 m. So far, both the resistivity value ρ1 and the depth value h1 of the first-layer laminated medium have been determined.

[0144] Obtain the resistivity σ of the current first-layer medium of the target to be measured m and the thickness h m After that, "impedance stripping" can be performed to strip off the determined part and continue to determine the resistivity σ of the remaining laminated medium m and the thickness h m . At this time, the electronic device can execute step S60.

[0145] Step S60: Based on the resistivity value and thickness of the current first-layer medium, perform "impedance stripping" layer by layer on the target to be measured to determine the resistivity value and thickness of each layer of the medium of the target to be measured.

[0146] In this embodiment, based on the determined part (the resistivity value and thickness of the current first-layer medium), "impedance stripping" can be performed on the target to be measured. As Figure 4 shown, Figure 4 is a flowchart of performing "impedance stripping" layer by layer on the target to be measured.

[0147] In this embodiment, "impedance stripping" may include S1, S2, S3, S4, and S5.

[0148] When performing impedance stripping, first execute S1.

[0149] S1: Use all the calculated resistivity values and thicknesses of the current first-layer medium as known conditions to perform impedance stripping to obtain the impedance of the remaining part of the target to be measured.

[0150] In this embodiment, the key to "impedance stripping" is that after determining the thickness and resistivity value of this layer of laminated medium, the impedance formula (formula (22)) can be used to realize the stripping of the determined laminated medium and obtain the remaining part of the target to be measured. Because after obtaining the thickness and resistivity value of the first layer, this formula can be used to determine the expression of the next layer and calculate the resistivity value and thickness of the next layer to realize "impedance stripping".

[0151] Specifically, the impedance form suitable for the remaining part of the target to be measured is given here, and the impedance of the remaining part of the target to be measured satisfies:

[0152]

[0153] where Z m is the top surface impedance of the mth layer in the target to be measured, and Z m+1is the bottom impedance of the m-th layer in the target to be measured, and at the same time is the top impedance of the (m + 1)-th layer in the target to be measured, where m ∈ [1, N], N is the total number of layered media layers in the target to be measured, and N ≥ 2; Z 0m is the characteristic impedance of the m-th layer, k m is the complex wavenumber of the m-th layer, h m is the thickness of the m-th layer.

[0154] It should be noted that formula (31) reveals the expression of the impedance of the layered medium, and can perform "impedance stripping" layer by layer according to the determined part of the layered medium. Each time of stripping can calculate the impedance of the remaining part of the target to be measured through formula (31). When the layered medium of each layer in the target to be measured has not been determined, at this time, the impedance of the first-layered medium is also undetermined (because the thickness of the first-layered medium has not been calculated yet), and "impedance stripping" cannot be performed temporarily. However, the impedance of the entire target to be measured (i.e., formula (24)) is determined. By using the impedance (the impedance in formula (22) and the impedance in formula (24) are the same concept, but two different expressions are needed in this article), the relationship between the "impedance stripping" method and the electric and magnetic fields is established, so that the present solution is feasible.

[0155] On this basis, the electronic device can execute S2.

[0156] S2: Determine the apparent resistivity curve of the remaining part of the target to be measured.

[0157] In this embodiment, the method for determining the apparent resistivity curve of the remaining part of the target to be measured is similar to the previous one (but the impedance substituted into the formula is the impedance of the remaining part of the target to be measured obtained by stripping the already calculated layered medium part). Please refer to the previous introduction and will not be elaborated here.

[0158] Continuing with the previous example, since the first layer of the three-layered medium model has been "impedance stripped", the obtained apparent resistivity curve is as Figure 5 shown.

[0159] After obtaining the apparent resistivity curve of the remaining part of the target to be measured, the electronic device can execute S3.

[0160] S3: Based on the apparent resistivity, determine the resistivity value of the current first-layer medium of the remaining part of the target to be measured.

[0161] Since "impedance stripping" has been performed, for the first layer of the remaining part of the target to be measured, the resistivity value of the layered medium of this layer can still be determined based on the apparent resistivity data in the current apparent resistivity curve, and the highest-frequency apparent resistivity is taken as the resistivity value of this layer.

[0162] Then, the electronic device executes S4.

[0163] S4: Based on the apparent resistivity curve of the remaining part of the object to be measured and the resistivity value of the current first-layer medium, determine the thickness of the current first-layer medium of the remaining part of the object to be measured.

[0164] For the process of determining the thickness, please refer to the previous text and will not be elaborated here. Continuing with the aforementioned example, determine the target point frequency at this time from Figure 5 and then substitute the resistivity value of this layer and the target point frequency into formula (30), and the thickness of the layered medium of this layer can be obtained.

[0165] Thus, the detection of one layer of layered medium is completed again, and the electronic device can continue to operate until the detection of the layered medium of the entire object to be measured is completed.

[0166] S5: Loop and execute steps S1 to S4 until the resistivity values and thicknesses of each layer of the medium of the object to be measured are solved.

[0167] In this embodiment, the electronic device can loop and execute steps S1 to S4 until the resistivity values and thicknesses of each layer of the medium of the object to be measured are solved (the last layer is a homogeneous half-space).

[0168] Finally, the detection of the layered medium of the object to be measured can be realized, and the data of the detected layered medium (resistivity, thickness, etc.) can be used for further interpretation and application, which will not be elaborated here too much.

[0169] This embodiment also provides a storage medium, which is installed in the electronic device and includes a stored program. When the program runs, it controls the device where the storage medium is located to execute the method for detecting layered media based on electromagnetic fields in this embodiment.

[0170] Moreover, this embodiment also provides an electronic device, which includes a memory and a processor. The memory is used to store information including program instructions, and the processor is used to control the execution of the program instructions. When the program instructions are loaded and executed by the processor, the steps of the method for detecting layered media based on electromagnetic fields in this embodiment are implemented.

[0171] In summary, the embodiments of the present application provide a method for detecting layered media based on electromagnetic fields, a storage medium, and an electronic device. In this solution, by acquiring the electric field data and magnetic field data of the target to be detected, the impedance and apparent resistivity curve of the target to be detected are determined; by mining the information in the apparent resistivity, the resistivity value of the current first layer of the target to be detected is determined, and further the thickness of the current first layer of the target to be detected is calculated. Then, based on the resistivity value and thickness of the current first layer of the medium, "impedance stripping" is performed layer by layer on the target to be detected, and accordingly, the resistivity value and thickness of each layer of the target to be detected are determined. By fully mining the information in the data obtained by electromagnetic detection technology, the "stripping impedance" method is designed. By stripping each layer of the medium of the detection target layer by layer, the thickness and resistivity of each layer of the medium are effectively calculated, realizing the detection of the layered medium of the detection target, which has the advantages of non-contact, pollution-free, low cost, simple operation, fast speed, and no need for coupling.

[0172] For the characteristics of different scenarios, for example, in the field of geophysical electromagnetic exploration, since the frequency is relatively low (generally not exceeding 10 4 Hz), the displacement current can be ignored, and the value of the apparent resistivity of the homogeneous half-space model is equal to the resistivity value of the half-space. Therefore, the apparent resistivity is calculated; while for high-frequency scenarios (exceeding 10 4 Hz), such as the detection of metal coatings, the displacement current cannot be ignored, and a new definition of apparent resistivity is designed applicable to the entire frequency band. For a homogeneous half-space medium, its value is the resistivity value of the homogeneous half-space (if for media such as metals, because their resistivity is small, the reciprocal of the apparent resistivity can also be taken and the apparent conductivity can be used for calculation). This enables this solution to be applied to a wider range of layered medium detection scenarios.

[0173] In this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0174] The above description is only for the embodiments of the present application and is not used to limit the protection scope of the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for detecting layered media based on electromagnetic fields, characterized in that, Including: Obtain the electric field data and magnetic field data of the target to be measured; Based on the electric field data and magnetic field data of the target to be measured, determine the impedance of the target to be measured; Based on the electric field data and magnetic field data of the target to be measured, determine the apparent resistivity curve of the target to be measured; Based on the apparent resistivity, determine the resistivity value of the current first-layer medium of the target to be measured; Based on the apparent resistivity curve of the target to be measured and the resistivity value of the current first-layer medium, determine the thickness of the current first-layer medium of the target to be measured; Based on the resistivity value and thickness of the current first-layer medium, perform layer-by-layer "impedance stripping" on the target to be measured to determine the resistivity value and thickness of each layer of the target to be measured.

2. The method for detecting layered media based on electromagnetic fields according to claim 1, wherein Based on the electric field data and magnetic field data of the target to be measured, determine the impedance of the target to be measured, including: Calculate the impedance using the following formula: Or Among them, Z is the impedance of the target to be measured, E is the electric field, and E x is the horizontal electric field component of the electric field E in the x direction, and E y is the horizontal electric field component of the electric field E in the y direction, H is the magnetic field, and H x is the horizontal magnetic field component of the magnetic field H in the x direction, and H y is the horizontal magnetic field component of the magnetic field H in the y direction.

3. The method for detecting layered media based on electromagnetic fields according to claim 1, characterized in that, If the frequency is higher than 10 4 Hz, based on the electric field data and magnetic field data of the target to be measured, determine the apparent resistivity curve of the target to be measured, including: Calculate the apparent resistivity using the following formula: where ρ s is the apparent resistivity, ω is the angular frequency, μ0 is the magnetic permeability of vacuum, Z is the impedance, and imag represents taking the imaginary part; Based on the calculated apparent resistivity, determine the apparent resistivity curve of the target to be measured.

4. The method for detecting layered media based on electromagnetic fields according to claim 1, wherein If the frequency is not higher than 10 4 Hz, based on the electric field data and magnetic field data of the target to be measured, determine the apparent resistivity curve of the target to be measured, including: Calculate the apparent resistivity using the following formula: where ρ s is apparent resistivity, ω is angular frequency, μ0 is magnetic permeability of vacuum, Z is impedance, and imag represents taking the imaginary part; Or, calculate the apparent resistivity using the following formula: Where, μ0 is the magnetic permeability of vacuum, ω is the angular frequency, and Z is the impedance; Based on the calculated apparent resistivity, determine the apparent resistivity curve of the target to be measured.

5. The method for detecting layered media based on electromagnetic fields according to claim 1, characterized in that Based on the apparent resistivity, determine the resistivity value of the current first-layer medium of the target to be measured, including: Judge whether the difference between the first three apparent resistivity data with the highest frequencies in the current apparent resistivity is within 1‰; If so, determine the apparent resistivity at the highest frequency in the apparent resistivity as the resistivity value of the current first-layer medium of the target to be measured; If not, expand the detection frequency range, adjust the highest frequency of the detection frequency to 10 times the original, update the electric field data and magnetic field data of the target to be measured, recalculate the impedance of the target to be measured, determine the new apparent resistivity curve, and then continue to judge until the resistivity value of the current first-layer medium of the target to be measured is determined.

6. The method for detecting layered media based on electromagnetic fields according to claim 1, wherein Based on the apparent resistivity curve of the target to be measured and the resistivity value of the current first-layer medium, determine the thickness of the current first-layer medium of the target to be measured, including: Determine the resistivity value of the current first-layer medium of the target to be measured and the target point frequency of the apparent resistivity curve; Calculate the thickness of the current first-layer medium of the target to be measured using the following formula: Among them, h m is the thickness of the current first layer of medium of the target to be measured, μ0 is the magnetic permeability of vacuum, f c is the target point frequency, σ m is the resistivity value of the current first layer of medium of the target to be measured.

7. The method for detecting layered media based on electromagnetic fields according to claim 6, wherein Based on the resistivity value and thickness of the current first-layer medium, perform layer-by-layer "impedance stripping" on the target to be measured to determine the resistivity value and thickness of each layer of the target to be measured, including: S1: Take all the calculated resistivity values and thicknesses of the current first-layer medium as known conditions, perform impedance stripping to obtain the impedance of the remaining part of the target to be measured; S2: Determine the apparent resistivity curve of the remaining part of the target to be measured; S3: Based on the apparent resistivity, determine the resistivity value of the current first-layer medium of the remaining part of the target to be measured; S4: Based on the apparent resistivity curve of the remaining part of the target to be measured and the resistivity value of the current first-layer medium, determine the thickness of the current first-layer medium of the remaining part of the target to be measured; S5: Loop and run steps S1 to S4 until the resistivity value and thickness of each layer of the target to be measured are solved.

8. The method for detecting layered media based on electromagnetic fields according to claim 7, characterized in that, In S1: The impedance of the remaining part of the target to be measured satisfies: Among them, Z m is the top surface impedance of the m-th layer in the target to be measured, and Z m+1 is the bottom surface impedance of the m-th layer in the target to be measured, and at the same time is the top surface impedance of the (m + 1)-th layer in the target to be measured, where m ∈ [1, N], N is the total number of layered media in the target to be measured, and N ≥ 2; Z 0m is the characteristic impedance of the m-th layer, k m is the complex wave number of the m-th layer, and h m is the thickness of the m-th layer.

9. A storage medium, characterized in that, The storage medium is installed in a device and includes a stored program. When the program runs, it controls the device where the storage medium is located to execute the electromagnetic field-based layered medium detection method according to any one of claims 1 to 8.

10. An electronic device, comprising a memory and a processor, the memory being used for storing information including program instructions, and the processor being used for controlling the execution of the program instructions, characterized in that: When the program instructions are loaded and executed by a processor, the steps of the electromagnetic field-based layered medium detection method according to any one of claims 1 to 8 are implemented.

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