Ultra-wideband electromagnetic method anisotropic medium three-dimensional forward modeling method and system

Abstract

The invention belongs to the technical field of electromagnetic exploration and numerical simulation. According to the ultra-wide-band electromagnetic method anisotropic medium three-dimensional forward modeling simulation method and system, on the basis of a vector finite element method, electric field equations of unified traditional current and displacement current are discretized, influences of any anisotropic conductivity, any anisotropic dielectric constant and magnetic conductivity are fully considered, and the three-dimensional forward modeling simulation of the anisotropic medium based on the electromagnetic method is achieved. And a basis is provided for theoretical research, field investigation and data inversion of an ultra-wideband electromagnetic method.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic exploration and numerical simulation, and in particular to an ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method and system. Background Art

[0002] The statements in this section merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] Frequency domain electromagnetic method is a geophysical technology that uses natural or artificial controllable source frequency domain electromagnetic waves to detect underground electrical structures. Traditional frequency domain electromagnetic methods include magnetotelluric method (MT), audio frequency magnetotelluric method (AMT), controlled source audio frequency magnetotelluric method (CSAMT), controlled source electromagnetic method (CSAMT), etc. The observation frequency of these methods is usually less than 100kHz. In recent years, significant progress in instrument technology has promoted the development of wireless electromagnetic wave detection technology and equipment, including radio frequency magnetotelluric method (RMT) and controlled source radio frequency magnetotelluric method (CSRMT), whose observation frequency can reach 1MHz and are widely used in near-surface environment exploration. At present, the observation frequency band (0~1MHz) covered by the frequency domain electromagnetic method spans ten orders of magnitude, which can be called ultra-wideband electromagnetic method, including low-frequency band MT (0~1KHz), medium-frequency band AMT, CSAMT, CSEM (10Hz~100KHz) and high-frequency band RMT, CSRMT (10KHz~1MHz). The detection depth can cover several meters to hundreds of kilometers underground. It is widely used in deep underground structure detection, engineering survey, mineral exploration and environmental engineering detection.

[0004] The calculation frequency of the traditional frequency domain electromagnetic numerical simulation method is usually lower than 10kHz, and induction diffusion is the dominant phenomenon. The numerical simulation usually adopts a quasi-static assumption and ignores the influence of displacement current. However, existing studies have shown that displacement current and dielectric constant have a great influence on the observation data in the RMT frequency band. Ignoring displacement current may lead to errors in inversion results, especially in high-resistance areas such as glaciers and granite, which may lead to data interpretation errors. Therefore, it is of great significance to consider the influence of dielectric constant and displacement current in high-frequency frequency domain electromagnetic simulation.

[0005] At present, the research on RF electromagnetic forward modeling mainly focuses on one-dimensional and two-dimensional models. However, affected by geological activities, the real geological structure is very complex, and an accurate three-dimensional geological model needs to be established to obtain accurate electromagnetic responses. At the same time, anisotropy is widely present in the earth's medium, and anisotropy has a non-negligible effect on the propagation of electromagnetic fields in the frequency domain. However, there is currently a lack of three-dimensional numerical simulation methods for frequency domain electromagnetic methods that simultaneously consider conduction current, displacement current, arbitrary anisotropic resistivity and dielectric constant. Summary of the invention

[0006] In order to overcome the shortcomings of the prior art, the present invention provides a three-dimensional forward modeling method and system for anisotropic media in an ultra-wideband electromagnetic method. Based on the vector finite element method, the electric field equations of the unified traditional current and displacement current are discretized, and the influence of arbitrary anisotropic conductivity, arbitrary anisotropic dielectric constant and magnetic permeability are fully considered, which provides a basis for theoretical research, field survey and data inversion of ultra-wideband electromagnetic method.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an ultra-wideband electromagnetic three-dimensional forward modeling method for anisotropic media.

[0009] A three-dimensional forward modeling method for anisotropic medium in ultra-wideband electromagnetic method includes the following processes:

[0010] An unstructured tetrahedral mesh three-dimensional model is constructed, and anisotropic conductivity, dielectric constant and magnetic permeability are assigned to different regions or different materials in the unstructured tetrahedral mesh three-dimensional model;

[0011] Constructing an electric field double-curl control equation for unified conduction current and displacement current, discretizing the electric field double-curl control equation by vector finite element, and applying boundary conditions to obtain a global finite element linear system equation;

[0012] The global finite element linear system equations are solved to obtain the solutions of two polarization modes. Based on the solutions of the two polarization modes, three-dimensional forward calculations are performed to obtain the electric field components, magnetic field components, impedance, phase, apparent resistivity and dipole response data.

[0013] In a second aspect, the invention provides an ultra-wideband electromagnetic three-dimensional forward modeling system for anisotropic media.

[0014] An ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation system, comprising:

[0015] The grid three-dimensional model construction unit is configured to: construct an unstructured tetrahedral grid three-dimensional model, in which anisotropic conductivity, dielectric constant and magnetic permeability are given to different regions or different materials;

[0016] A global finite element linear system equation generating unit is configured to: construct an electric field double-curl control equation for unified conduction current and displacement current, perform vector finite element discretization on the electric field double-curl control equation, and apply boundary conditions to obtain a global finite element linear system equation;

[0017] The three-dimensional forward modeling calculation unit is configured to solve the global finite element linear system equation to obtain the solutions of two polarization modes, and perform three-dimensional forward modeling calculations based on the solutions of the two polarization modes to obtain electric field components, magnetic field components, impedance, phase, apparent resistivity and dipole response data.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention proposes a three-dimensional forward simulation method for anisotropic media in an ultra-wideband electromagnetic method, which adopts a complete and unified electric field double-curl equation and considers the influence of traditional current and displacement current at the same time, and can simulate the electromagnetic response within an ultra-wideband range.

[0020] 2. The present invention utilizes unstructured tetrahedral grids to flexibly simulate complex geological structures, accurately capture changes in terrain features and geological layers, and enhance the realism and reliability of the simulation.

[0021] 3. The present invention takes into account the influence of anisotropic conductivity, anisotropic dielectric constant and magnetic permeability, and can more accurately simulate the electromagnetic response under complex geological structures, thereby improving the reliability and accuracy of the simulation results.

[0022] 4. The present invention adopts a direct solver and a parallel solution, which can efficiently solve the linear system, ensure the accuracy and efficiency of the simulation, and improve the practicality and application value of the algorithm.

[0023] 5. The present invention solves the limitation of the prior art that it is impossible to simultaneously consider displacement current, conduction current and arbitrary anisotropic media, and provides a basis for theoretical research on ultra-wideband electromagnetic method and inversion interpretation of actual observation data, so that it can be better applied to deep earth scientific exploration, engineering survey, mineral resource exploration, environmental engineering exploration and other fields.

[0024] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 A flow chart of a three-dimensional forward modeling method for anisotropic media using ultra-wideband electromagnetic method provided in Example 1 of the present invention;

[0027] Figure 2 The arbitrary anisotropic conductivity block anomaly model provided in Case 1 of Embodiment 1 of the present invention;

[0028] Figure 3 A schematic diagram of the comparison of the results of the present invention and Bai et al. in the arbitrary anisotropic conductivity block anomaly model provided in Case 1 of Example 1 of the present invention, where at x=0 m on the surface, the first to fourth columns represent the xy mode apparent resistivity, the yx mode apparent resistivity, the xy mode phase, and the yx mode phase, respectively;

[0029] Figure 4 A one-dimensional layered model and a schematic diagram of electrical parameters thereof provided for Case 2 in Example 1 of the present invention;

[0030] Figure 5 A comparison diagram of the responses calculated by the present invention and the 1D analytical solution in the double-layer model provided for Case 2 in Example 1 of the present invention, wherein the first to fourth columns represent the xy mode apparent resistivity, the yx mode apparent resistivity, the xy mode phase, and the yx mode phase, respectively;

[0031] Figure 6 A schematic diagram of a three-dimensional forward modeling system for anisotropic media using ultra-wideband electromagnetic method provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0034] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0035] Embodiment 1:

[0036] This implementation proposes a three-dimensional forward modeling method for anisotropic media in ultra-wideband electromagnetic methods, which makes up for the problem that the existing radio frequency magnetotelluric three-dimensional forward modeling method ignores the influence of displacement current and cannot calculate the dielectric constant and its anisotropy; it discretizes the electric field equations of unified traditional current and displacement current based on the vector finite element method, and has the following innovations and advantages: the ability to simulate electromagnetic responses within an ultra-wideband range; considering the influence of anisotropic conductivity, anisotropic dielectric constant and magnetic permeability, it has the advantage of obtaining more accurate electromagnetic responses; using unstructured tetrahedral grids, it can flexibly simulate complex geological structures; using direct solvers and parallel solutions to solve linear systems to ensure the accuracy and efficiency of simulation.

[0037] Specifically, Figure 1 As shown, the following process is included:

[0038] S1: Construct unstructured tetrahedral mesh 3D model.

[0039] According to the actual geological conditions and research needs, a fine three-dimensional geological structure geometric model is constructed using software such as Comsol or GID, and an unstructured tetrahedral mesh discretized geometric model is adopted. The present invention combines three-dimensional geological modeling technology with unstructured tetrahedral mesh technology, thereby having the advantage of accurately capturing complex terrain features and complex geological structures.

[0040] S2: Assignment of anisotropic conductivity, anisotropic permittivity and magnetic permeability material properties.

[0041] In the unstructured tetrahedral mesh three-dimensional model, physical properties such as anisotropic conductivity, dielectric constant and magnetic permeability are assigned to different regions or different materials to reflect the electromagnetic characteristics in the real geological environment. The Dirichlet boundary conditions imposed on the external boundaries of the model are calculated by the plane wave one-dimensional layered medium forward simulation algorithm, which takes into account the influence of conductivity and dielectric constant anisotropy and magnetic permeability, thereby improving the accuracy of the boundary conditions.

[0042] In nature, conductivity and dielectric constant vary greatly, while magnetic permeability varies less, so only isotropic magnetic permeability is considered. In anisotropic earth media, conductivity and relative dielectric constant are tensors that can be expressed using the Euler transformation of the principal axis direction parameters:

[0043]

[0044] In formula (1) and (2), σ x , σ y and σ z are the three principal axis conductivities, ε x , ε y and ε z are the three principal axis permittivity, α S , α D and α L are the three Euler rotation angles, the superscripts “σ” and “ε” are used to distinguish the conductivity from the dielectric constant, R x and R z is defined as the Euler rotation matrix, expressed as:

[0045]

[0046]

[0047] In this implementation, after applying the Dirichlet boundary condition, the finite element coefficient matrix A of the two polarization modes at each frequency is the same, and only the right-hand side terms are different.

[0048] S3: Construct the electric field dual-curl control equations that unify the conduction current and displacement current.

[0049] The ultra-wideband electromagnetic method forward simulation covers the diffusion phenomenon of low-frequency electromagnetics and the wave phenomenon of high-frequency electromagnetics, which is controlled by the complete Maxwell equations, including its conduction current density and displacement current density terms. iωt And perform Fourier transform, the expressions of Faraday's law and Ampere-Maxwell equation are:

[0050]

[0051] Where E and H represent the electric field and magnetic field respectively. ω is the angular frequency, where ω = 2πf, f is the frequency, μ is the magnetic permeability, μ = μ r μ0,μ r is the relative magnetic permeability, μ0 is the vacuum magnetic permeability, J and D represent the conduction current and displacement current respectively, and their constitutive relations are shown as follows:

[0052] J = σE (7);

[0053] D = εE (8);

[0054] Taking the curl on both sides of formula (5), and substituting formulas (6), (7) and (8) into formula (5) to eliminate the magnetic field term, we can obtain the frequency domain electric field double curl control equation:

[0055]

[0056] S4: The electric field double curl control equation is discretized by vector finite element and boundary conditions are applied. The frequency domain electromagnetic control equation (9) is processed by Galerkin finite element analysis, and the weak form integral equation of the control equation is derived as follows:

[0057]

[0058] Where Ω represents the model domain under study and N represents the vector linear interpolation basis function of the tetrahedral element, which is defined as:

[0059]

[0060] Where L is the node basis function, l is the length of the edge, the superscript “e” represents the tetrahedral unit number, and the subscripts “i”, “i1”, and “i2” represent the edge number in the tetrahedral unit e, the starting node of the i-th edge, and the terminal node of the i-th edge, respectively.

[0061] Using the first vector Green's theorem, the discretized form of equation (12) is obtained in each tetrahedral unit:

[0062]

[0063] Among them, the stiffness matrix K, M σ and M ε Defined as:

[0064]

[0065] Where Ωe represents the tetrahedral unit domain, the subscripts "i" and "j" represent the edge numbers, and the above integral is calculated by analytical method. The local matrix of formula (12) is globally assembled and Dirichlet boundary is applied to obtain the global finite element linear system equation:

[0066] AE = b (16);

[0067] Where A=K+(ω 2 M ε +iωM σ ), is a complex sparse symmetric matrix of size Ne×Ne, the electric field vector to be solved on the edge of E and b represent the right-hand term containing boundary condition information, both of which have a size of Ne×1, and Ne is the number of edges in the model grid.

[0068] S5: Parallel solution of finite element sparse linear equations.

[0069] The direct solver PARDIASO is used to solve the finite element sparse linear equations. Since the finite element coefficient matrix A is the same in the two polarization modes, only one matrix decomposition and two back substitutions are needed to obtain the solutions of the two polarization modes, which improves the solution efficiency.

[0070] In this implementation, a parallel computing method is adopted, and the parallel computing includes frequency point process parallelism and PARDIASO OpenMP thread parallelism. The double-layer parallelism further improves the computing efficiency.

[0071] S6: Solve the electric field component, magnetic field component, impedance, phase, apparent resistivity, and dipole response data.

[0072] When the measuring point is in the e-th tetrahedral unit, the three components of the electric field at the measuring point are It can be expressed by a vector shape function as:

[0073]

[0074] in, are the three components of the vector basis function, is the solution on the edge. According to Faraday's law, the three components of the magnetic field at the measuring point are It is expressed as:

[0075]

[0076] in, are the three components of the vector basis function, It is the solution on the edge.

[0077] The components of the impedance tensor Z xx , Z xy , Z yx , Z yy The calculation expression is:

[0078]

[0079] Among them, E x1 , E x2 , E y1 , E y2 , H x1 , H x2 , H y1 , H y2 Are the horizontal components of the electric field and magnetic field calculated at the measuring point. The subscripts “x” and “y” represent two horizontal directions, and the subscripts “1” and “2” represent two polarization modes.

[0080] After calculating the impedance tensor, the apparent resistivity and phase can be obtained, namely:

[0081]

[0082] Among them, Z ij Represents the components of the impedance tensor, with “i” and “j” representing the “x” and “y” directions respectively.

[0083] The calculation expression of the tilt vector is:

[0084]

[0085] Among them, H x1 , H x2 , H y1 , H y2 , H z1 , H z2 are the three components of the magnetic field at the measuring point. The subscripts “x”, “y” and “z” represent the directions of the three components, and the subscripts “1” and “2” represent the two polarization modes.

[0086] In order to better illustrate the advantages and purposes of the present invention and verify the correctness and accuracy of the three-dimensional ultra-wideband forward modeling algorithm based on vector finite elements, the present invention uses two cases for verification. In the first case, the algorithm of the present invention is compared with the open source algorithm of Bai et al. (2022) to verify the accuracy of the magnetotelluric forward modeling and anisotropic algorithm under low-frequency conditions. In the second case, the algorithm of the present invention is compared with the one-dimensional radio frequency magnetotelluric analytical solution to verify the accuracy of the high-frequency range calculation considering the displacement current in the frequency range of 10kHz to 1MHz.

[0087] Case 1 discloses an optimization of the open source arbitrary anisotropic conductivity block anomaly model of Bai et al. (2022). The algorithm of the present invention is compared with the hybrid finite element method algorithm based on the Aψ potential control equation proposed by Bai et al. (2022) to verify the accuracy of the algorithm in low-frequency conditions.

[0088] Arbitrary anisotropic conductivity block anomaly model such as Figure 2 As shown in Figure 1, a block with a size of 20km×40km×10km is embedded in the isotropic homogeneous half space, located at the center of the coordinates (0km, 0km, 5km). The resistivity of the homogeneous earth is 1000Ω·m, and the main resistivity of the block is ρ x / ρ y / ρ z =100 / 10 / 100Ω·m, the anisotropy angle is The relative permeability of the entire model is 1 and the dielectric constant is 0. The computation frequency is 1 Hz. The model consists of 528,081 tetrahedrons and 621,174 edges. The computation took 127 seconds using 2 OpenMP threads.

[0089] Figure 3 A comparison of the apparent resistivity and phase results for the xy- and yx-modes at x = 0 m on the surface is shown, and the results calculated by the algorithm of the present invention are consistent with the results of Bai et al. (2022). This shows that the algorithm of the present invention can accurately calculate the low-frequency MT response with arbitrary conductivity anisotropy.

[0090] Case 2 discloses a preferred layered model such as Figure 4 As shown, the first layer of the double-layer model of the model is composed of limestone with a thickness of 10 meters, and its isotropic resistivity is 2000Ω·m and its isotropic dielectric constant is 8ε_0. The second layer is a gneiss basement, and its isotropic resistivity is 20000Ω·m and its dielectric constant anisotropy value is ε x / ε y / ε z =8ε0 / 5ε0 / 6ε0, anisotropy angle and is 0, and The angle of the angle is 45°. The frequency range of the calculation is from 10kHz to 1MHz, with a total of 11 logarithmically spaced points. The model consists of 922150 tetrahedrons and 1090145 edges. The parallel calculation at 11 frequencies takes a total of about 544 seconds.

[0091] Figure 5 The consistency between the apparent resistivity and phase results obtained by the present invention and the one-dimensional analytical calculation is demonstrated, proving that the algorithm of the present invention can accurately calculate high-frequency RMT response data with dielectric anisotropy constants. For the model of Case 2, two OpenMP threads are used to solve a single frequency equation, and the time required for serial calculation of 11 frequencies is 5363.8 seconds. The time required to calculate all frequencies using 11 parallel processes is 552.1 seconds, and the parallel calculation speed is 9.7 times that of the serial one, with a parallel efficiency of 88.3%, indicating that the present invention has a high parallel calculation efficiency.

[0092] Embodiment 2:

[0093] like Figure 6 As shown, this implementation provides an ultra-wideband electromagnetic method anisotropic medium three-dimensional forward simulation system, including:

[0094] The grid three-dimensional model construction unit is configured to: construct an unstructured tetrahedral grid three-dimensional model, in which anisotropic conductivity, dielectric constant and magnetic permeability are given to different regions or different materials;

[0095] A global finite element linear system equation generating unit is configured to: construct an electric field double-curl control equation for unified conduction current and displacement current, perform vector finite element discretization on the electric field double-curl control equation, and apply boundary conditions to obtain a global finite element linear system equation;

[0096] The three-dimensional forward modeling calculation unit is configured to solve the global finite element linear system equation to obtain the solutions of two polarization modes, and perform three-dimensional forward modeling calculations based on the solutions of the two polarization modes to obtain electric field components, magnetic field components, impedance, phase, apparent resistivity and dipole response data.

[0097] It is understandable that the above-mentioned various units can be separately or all combined into one or several other units to constitute, or some (some) units therein can also be split into multiple smaller units in function to constitute, which can achieve the same operation without affecting the realization of the technical effects of the embodiments of the present application. The above-mentioned units are divided based on logical functions. In practical applications, the function of a unit can also be realized by multiple units, or the function of multiple units can be realized by one unit. In other embodiments of the present application, the system can also include other units. In practical applications, these functions can also be implemented with the assistance of other units, and can be implemented by the collaboration of multiple units.

[0098] According to another embodiment of the present application, the system described in this embodiment can be constructed, and the method of Example 1 of the present application can be implemented by running a computer program (including program code) capable of executing the steps involved in the corresponding method described in Example 1 on a general computing device such as a computer including processing elements and storage elements such as a central processing unit (CPU), random access memory (RAM), and read-only memory (ROM). The computer program can be recorded on, for example, a computer-readable recording medium, and loaded into the above-mentioned computing device through the computer-readable recording medium and run therein.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A three-dimensional forward modeling method for anisotropic media in ultra-wideband electromagnetic method, characterized in that: The process includes: An unstructured tetrahedral mesh three-dimensional model is constructed, and anisotropic conductivity, dielectric constant and magnetic permeability are assigned to different regions or different materials in the unstructured tetrahedral mesh three-dimensional model; Constructing an electric field double-curl control equation for unified conduction current and displacement current, discretizing the electric field double-curl control equation by vector finite element, and applying boundary conditions to obtain a global finite element linear system equation; The global finite element linear system equations are solved to obtain the solutions of two polarization modes. Based on the solutions of the two polarization modes, three-dimensional forward calculations are performed to obtain the electric field components, magnetic field components, impedance, phase, apparent resistivity and dipole response data.

2. The ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method according to claim 1, characterized in that: The electric field double-curl control equations for unified conduction current and displacement current are constructed, including: Where μ = μ r μ0,μ r is the relative magnetic permeability, μ0 is the vacuum magnetic permeability, ω is the angular frequency, E represents the electric field, and ε is the dielectric constant.

3. The ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method according to claim 1, characterized in that: The electric field double curl control equation is discretized by vector finite element, and boundary conditions are applied to obtain a global finite element linear system equation, including: Finite element analysis is used to process the electric field double curl control equation, and the weak form integral equation of the control equation is derived: Where Ω represents the model domain under study, N represents the vector linear interpolation basis function of the tetrahedral element, Where L is the node basis function, l is the length of the edge, e represents the tetrahedral unit number, i, i1, i2 represent the edge number in the tetrahedral unit e, the starting node of the i-th edge, and the terminal node of the i-th edge, respectively; Using the first vector Green's theorem, the discretized form is obtained in each tetrahedral unit: in, and are the stiffness matrices K and M respectively σ and M ε Elements in The local matrix in discrete form is assembled globally and Dirichlet boundary is applied to obtain the global finite element linear system equation: AE = b, where A = K + (ω 2 M ε +iωM σ ), is a complex sparse symmetric matrix of size Ne×Ne, E is the electric field vector to be solved on the edge, b represents the right-hand term containing boundary condition information, both of which have a size of Ne×1, and Ne is the number of edges in the model grid.

4. The ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method according to claim 1, characterized in that: Where Ωe represents the tetrahedral unit domain, and i and j represent the edge numbers.

5. The ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method according to claim 1, characterized in that: The direct solver PARDIASO is used to solve the global finite element linear system equations.

6. The ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method according to claim 1, characterized in that: When the measuring point is in the eth tetrahedral unit, the three components of the electric field at the measuring point are Represented by a vector shape function: in, are the three components of the vector basis function, is the solution on the edge; Three components of magnetic field at the measuring point It is expressed as: in, are the three components of the vector basis function, is the solution on the edge, i=1,…,6 is the local number of the tetrahedron edge.

7. The ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method according to claim 1, characterized in that: The components of the impedance tensor Z xx , Z xy , Z yx , Z yy The calculation expression is: Among them, E x1 , E x2 , E y1 , E y2 , H x1 , H x2 , H y1 , H y2 are the horizontal components of the electric field and magnetic field calculated at the measuring point. The subscripts x and y represent two horizontal directions, and subscripts 1 and 2 represent two polarization modes.

8. The ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method according to claim 7, characterized in that: Calculate the apparent resistivity ρ ij and phase φ ij , include: Among them, Z ij represents the components of the impedance tensor, i, j represent the x and y directions respectively, μ0 is the magnetic permeability of vacuum, and ω is the angular frequency.

9. The ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation method according to claim 1, characterized in that: The tilt response data is the tilt vector, and the tilt vector T zx and T zy The calculation expression is: Among them, H x1 , H x2 , H y1 , H y2 , H z1 , H z2 are the three components of the magnetic field at the measuring point. The subscripts x, y, and z represent the directions of the three components. Subscripts 1 and 2 represent the two polarization modes.

10. An ultra-wideband electromagnetic anisotropic medium three-dimensional forward simulation system, characterized in that: include: The grid three-dimensional model construction unit is configured to: construct an unstructured tetrahedral grid three-dimensional model, in which anisotropic conductivity, dielectric constant and magnetic permeability are given to different regions or different materials; A global finite element linear system equation generating unit is configured to: construct an electric field double-curl control equation for unified conduction current and displacement current, perform vector finite element discretization on the electric field double-curl control equation, and apply boundary conditions to obtain a global finite element linear system equation; The three-dimensional forward modeling calculation unit is configured to solve the global finite element linear system equation to obtain the solutions of two polarization modes, and perform three-dimensional forward modeling calculations based on the solutions of the two polarization modes to obtain electric field components, magnetic field components, impedance, phase, apparent resistivity and dipole response data.

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