A full current wave impedance resistivity detection method and system

Abstract

The application provides a full current wave impedance apparent resistivity detection method and system, and belongs to the technical field of survey geophysics. The method realizes apparent resistivity detection of a target area by using a radio frequency magnetotelluric method (RMT). The method mainly comprises the following steps: collecting detection data, using a sensor with a frequency range covering 1 MHz to obtain orthogonal electric field components and magnetic field components at measuring points in a detection area; obtaining dielectric constants and magnetic permeabilities of a shallow surface layer; and using the detection data to calculate full current wave impedance apparent resistivities at the measuring points by using a full current wave impedance apparent resistivity model which is not limited by quasi-static conditions. In the application, the full current wave impedance apparent resistivity model considering displacement current is derived from Maxwell equations, so that the model is not limited by quasi-static conditions and will not cause distortion of apparent resistivity at high frequencies due to non-compliance with quasi-static assumptions. The model can measure both artificial source excited electromagnetic fields and natural electromagnetic fields.

Description

Technical Field

[0001] This invention belongs to the field of exploration geophysics technology, specifically relating to a method and system for detecting apparent resistivity of total current wave impedance. Background Technology

[0002] In radio frequency magnetotelluric (RFT) studies, the quasi-static approximation of the magnetotelluric method is often referenced, using the definition of Carnia apparent resistivity. The traditional Carnia apparent resistivity utilizes the horizontal component of the magnetic field. , (or , The ratio of the two is calculated (called impedance). (or ), thereby obtaining the apparent resistivity distribution of the underground Kania. (or The purpose of this method is to determine the distribution characteristics of underground electrical structures. Although the Carnia apparent resistivity has a wide applicability, the operating frequency band of radio frequency magnetotellurics (RFMT) is mainly 10~300kHz, with some instrument systems reaching 1MHz. Under these high-frequency conditions, especially in high-resistivity media regions, the contribution of the electromagnetic field displacement current component (compared to the conduction current) is not negligible. At this point, the displacement current component and the conduction current component are roughly equal in magnitude. Therefore, the electromagnetic field propagation in RFMT does not follow quasi-static conditions (conduction current is much greater than displacement current). Using the Carnia apparent resistivity under these conditions will cause data distortion, leading to significant deviations in the interpretation of RMT data.

[0003] Therefore, due to the limitations of quasi-static measurement conditions, the apparent resistivity calculated using traditional Carnia apparent resistivity will be severely distorted under high frequency and high impedance conditions, which will greatly affect the accuracy of apparent resistivity in RMT and thus affect the accuracy of underground electrical structure detection. Summary of the Invention

[0004] This invention aims to solve the technical problem that the apparent resistivity calculated using traditional Carnia apparent resistivity results in severe distortion under high-frequency, high-impedance conditions due to limitations imposed by quasi-static measurement conditions. Therefore, it provides a method and system for detecting apparent resistivity using all-current-wave impedance. The technical solution of this invention offers a novel all-current-wave impedance apparent resistivity detection technology that is not limited by quasi-static conditions and can obtain more accurate apparent resistivity under high-frequency, high-impedance (non-quasi-static) conditions.

[0005] Therefore, the present invention provides the following technical solution:

[0006] On the one hand, the present invention provides a method for detecting the apparent resistivity of the total current wave impedance using radio frequency magnetotelluric (RMT) and includes the following steps:

[0007] Data was collected by deploying sensors with a frequency range covering 1MHz at measurement points within the detection area to obtain orthogonal electric and magnetic field components, as well as the dielectric constant of the shallow surface layer. and permeability ;

[0008] Using the detection data, the apparent resistivity of the total current wave impedance at the measuring point is calculated through a total current wave impedance apparent resistivity model that is not limited by quasi-static conditions, and the detection results of the apparent resistivity of the total current wave impedance in the detection area are obtained.

[0009] The apparent resistivity model of the total current wave impedance, which is not subject to quasi-static conditions, is as follows:

[0010]

[0011] In the formula, To obtain the apparent resistivity of the total current wave impedance for RMT (Remote Radio Frequency Magnetism) For total current impedance, Angular frequency, Where is the dielectric constant. is the magnetic permeability.

[0012] Optionally, the total current wave impedance is determined based on the orthogonal electric and magnetic field components in the detection data, satisfying:

[0013] TE mode: Total current impedance The corresponding representation is : , Indicates electric field strength In a spatial rectangular coordinate system The directional component, i.e., the electric field along the x-direction; Indicates magnetic field strength In a spatial rectangular coordinate system The directional component, i.e., the magnetic field along the y-direction;

[0014] TM Mode: Total Current Surge Impedance The corresponding representation is : , Indicates electric field strength The y-direction component in a spatial rectangular coordinate system, i.e., the electric field along the y-direction; Indicates magnetic field strength The x-direction component in a spatial rectangular coordinate system, i.e., the magnetic field along the x-direction.

[0015] As will be known to those skilled in the art, the TE and TM modes described above are applicable to 1D / 2D layered / 3D non-homogeneous geology. For 1D homogeneous medium models, either the TE or TM mode is used; for 2D homogeneous medium models, a dual TE / TM mode can be used; for 3D homogeneous medium models, full tensor impedance calculation is employed.

[0016] Optionally, under low-frequency conditions, when displacement current is neglected, the dielectric constant of the shallow layer is... Setting it to 0 corresponds to the parameter used for the apparent resistivity of the total current wave impedance at the measuring point. express: .

[0017] Optionally, the electric and magnetic fields measured in the detection area are natural electromagnetic fields or electromagnetic fields generated by artificial field sources, and are applicable to 1-3 multi-dimensional scenarios.

[0018] Secondly, the present invention also provides a method for detecting underground electrical structures, comprising the following steps:

[0019] The apparent resistivity of the total current wave impedance at the measuring point in the detection area is obtained by using the above-mentioned method for detecting the total current wave impedance, and then the apparent resistivity curve of each measuring point is obtained.

[0020] The apparent resistivity curve data of all measuring points can be used as observation data, and the magnetotelluric inversion algorithm can be introduced to obtain the three-dimensional resistivity structure model of the underground, thus completing the detection of the underground electrical structure of the detection area.

[0021] Thirdly, the present invention also provides a detection system based on the above-mentioned all-current wave impedance apparent resistivity detection method, including a detection device, a data processing unit, and a power supply unit working in concert:

[0022] The detection equipment includes an electric field sensor, a magnetic field sensor, physical testing elements, and a GPS / BeiDou-based positioning and synchronization module deployed within the detection area. The electric field sensor detects electric field data, the magnetic field sensor detects magnetic field data, and the physical testing elements acquire the dielectric constant of the shallow surface layer. and permeability The positioning synchronization module is used to provide the coordinates of the measuring points and ensure synchronous acquisition of multiple measuring points.

[0023] The data processing unit includes a signal receiver and a computer terminal. The signal receiver is communicatively connected to the detection device to acquire detection data and transmit it to the computer terminal. The computer terminal uses the detection data to calculate the apparent resistivity of the total current wave impedance at the measurement point using a total current wave impedance apparent resistivity model that is not limited by quasi-static conditions.

[0024] The power supply unit provides power to the hardware of the detection system.

[0025] In four aspects, the present invention also provides a computer terminal, comprising:

[0026] One or more processors and a memory storing one or more computer programs;

[0027] The processor invokes a computer program to implement the steps of the all-current wave impedance apparent resistivity detection method.

[0028] Fifthly, the present invention also provides a computer-readable storage medium including a computer program, which is invoked by a processor to implement the steps of the all-current wave impedance apparent resistivity detection method.

[0029] Compared with the prior art, the present invention achieves the following progress and effects:

[0030] This invention provides a novel method for detecting apparent resistivity of all-current wave impedance. This model is not limited by quasi-static conditions and will not cause apparent resistivity distortion at high frequencies due to non-compliance with the quasi-static assumptions. It also holds true under quasi-static conditions. This invention can measure both electromagnetic fields generated by artificial source excitation and natural electromagnetic fields.

[0031] This invention, starting from Maxwell's equations, derives a full current wave impedance apparent resistivity model considering displacement current. Therefore, under high-frequency conditions, especially in high-resistivity media, it can fully account for the contribution of electromagnetic field displacement current components. This allows the full current wave impedance apparent resistivity to effectively overcome the distortion problem of the Carnia apparent resistivity in the high-frequency range when using real permittivity and permeability for forward modeling. Furthermore, using forward modeling with free-space permeability and permittivity, the full current wave impedance apparent resistivity provides a more accurate apparent resistivity response than the Carnia apparent resistivity, especially under geological conditions with low permittivity. In magnetic geothermal conditions (permeability greater than free-space permeability), when the relative permittivity is greater than or equal to the relative permeability, the accuracy of the full current wave impedance apparent resistivity is also higher than that of the Carnia apparent resistivity, and it can suppress its high-frequency distortion. Attached Figure Description

[0032] Figure 1 It is a comparison of the apparent resistivity of the total current wave impedance (technical solution of this invention) and the apparent resistivity curve of Carnia under uniform half-space and real uniform half-space.

[0033] Figure 2 It is a comparison of the apparent resistivity of the total current wave impedance (technical solution of this invention) and the apparent resistivity of Carnia under different dielectric constants;

[0034] Figure 3This is a comparison chart of the apparent resistivity of the total current wave impedance (technical solution of this invention) and the apparent resistivity of Carnia under different magnetic permeabilities;

[0035] Figure 4 It is a comparison chart of the apparent resistivity of the total current wave impedance (technical solution of this invention) and the apparent resistivity of the Carnia curve under different actual relative permittivity, corresponding to a uniform half-space and a real uniform half-space.

[0036] Figure 5 It is a comparison chart of the apparent resistivity of the total current wave impedance (technical solution of this invention) and the apparent resistivity of the three-layer dielectric model H-type and the three-layer dielectric model Q-type.

[0037] Figure 6 This is a flowchart illustrating the detection technology provided by the technical solution of this invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical features involved in the various embodiments of the invention described below can be combined with each other as long as they do not conflict with each other.

[0039] It should be noted that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, and the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0041] The present invention proposes a method and system for detecting apparent resistivity of the full current wave impedance. Its core is to deduce a full current wave impedance apparent resistivity model that is not limited by quasi-static conditions. Using this model, higher accuracy apparent resistivity can be obtained under high frequency and high impedance (non-quasi-static conditions).

[0042] The derivation of the apparent resistivity model of the all-current wave impedance, which is not subject to quasi-static conditions, is as follows:

[0043] The electromagnetic field of a plane wave can be represented by Maxwell's equations, assuming that the spatial conductivity is _____. The dielectric constant is Magnetic permeability is The Maxwell equations in the frequency domain can be expressed as follows:

[0044] (1)

[0045] (2)

[0046] (3)

[0047] (4)

[0048] In the formula, For curl operator, and These are the electric field strength and the magnetic field strength, respectively. , , These represent the electrical conductivity, dielectric constant, and magnetic permeability of the medium, respectively. Angular frequency, For frequency, the time factor is taken as... q is the free charge volume density.

[0049] The four fundamental quantities in an electromagnetic field are expressed through the permeability of a physical property parameter. and dielectric constant Related to:

[0050] (5)

[0051] (6)

[0052] In the formula, and These are the electric displacement vector and the magnetic induction intensity, respectively.

[0053] In the right-hand side of equation (2) above, the conduction current density Displacement current density The conduction current is generated by the directional movement of free charges in the conductive medium, while the displacement current is generated by a changing electric field. When the conduction current is much larger than the displacement current, this simplification is called the quasi-static approximation. The frequency range of MT measurements is... - Hz, assuming the underground resistivity is 10000 Meanwhile, taking the highest measurement frequency of MT at 1000Hz, with a relative permittivity of 5, the displacement current is much smaller than the conduction current and can be ignored. However, the measurement frequency range of RMT is 10-300kHz. When the measurement frequency is 300kHz, using the same geological parameters as above, the displacement current... A is comparable in magnitude to the conduction current, therefore it cannot be ignored and no longer follows the quasi-static condition.

[0054] To study the propagation law of electromagnetic fields considering displacement current, this invention first studies the electromagnetic field in a homogeneous medium. Taking the curl of both sides of equations (1) and (2), and combining them with equations (3) and (4), the Helmholtz equations for the electric and magnetic fields can be obtained.

[0055] (7)

[0056] (8)

[0057] wavenumber The expression is:

[0058] (9)

[0059] Assuming the direction is vertically downwards, in a homogeneous and isotropic medium, the Helmholtz equations for the electric and magnetic fields can be written as the following wave equations:

[0060] (10)

[0061] (11)

[0062] (12)

[0063] (13)

[0064] In the formula, Represents the spatial rectangular coordinate system direction, , They represent electric field strength, respectively. The corresponding directional components in a spatial rectangular coordinate system; , They represent magnetic field strengths, respectively. The corresponding directional components in a spatial rectangular coordinate system.

[0065] Based on the boundary conditions and initial values, the general solution to the differential equation is:

[0066] (14)

[0067] (15)

[0068] in, and The initial values ​​of the electromagnetic field at the upper boundary are... Let be the time factor. Substituting equations (11) and (13) into the boundary conditions and combining them with the definition of impedance, we can obtain the impedance in a uniform medium considering displacement current. The expression for the impedance (ignoring displacement current) is: ):

[0069] (16)

[0070] This differs from the impedance in a homogeneous medium considered in the above equation, which takes displacement current into account. The expression for impedance Z, neglecting displacement current, is: .

[0071] Square the expression for the impedance in a homogeneous medium considering displacement current, and then multiply the numerator and denominator by the same factor. The magnitude of the RMT impedance can then be obtained as:

[0072] (17)

[0073] Multiply both sides of the equation again Squaring both sides of the equation and simplifying, we get:

[0074] (18)

[0075] The above formula is about The quadratic equation in one variable. Solving this equation, discarding roots with no physical meaning, yields... The valid solution is:

[0076] (19)

[0077] Obtain the apparent resistivity of the total current wave impedance in radio frequency magnetotelluric method (RMT). The expression is as follows:

[0078] (20)

[0079] The apparent resistivity of the total current wave impedance derived from the above formula It can fundamentally solve the problem of quasi-static condition limitations and ensure the detection accuracy of apparent resistivity in RMT under high frequency and high impedance conditions.

[0080] It should be understood that under low-frequency conditions, when the displacement current is negligible (the dielectric constant can be set to 0), the above formula can be simplified to the apparent resistivity of Carnia. : Therefore, this further proves the rationality of the above-described reasoning process of the present invention.

[0081] Based on the above reasoning, the present invention provides a method for detecting apparent resistivity of total current wave impedance, which applies radio frequency magnetotelluric (RMT) and includes the following steps:

[0082] Step 1: Collect detection data. Within the detection area, deploy sensors covering a frequency range of 1MHz at measurement points to acquire orthogonal electric and magnetic field components; and obtain the dielectric constant of the shallow surface layer. and permeability ;

[0083] Step 2: Using the probe data, calculate the apparent resistivity of the total current wave impedance at the measuring point using a total current wave impedance apparent resistivity model that is not limited by quasi-static conditions.

[0084] Application examples:

[0085] When applying the technical solution of this invention to the observation of natural electromagnetic fields, the method for detecting the apparent resistivity of the total current wave impedance of this invention includes the following steps:

[0086] (1) Observation Design: Determine the observation target and depth range, determine the measurement frequency range based on the actual exploration depth requirements and the background conductivity of the survey area, and determine the observation time length and signal sampling rate of a single measuring point based on the required measurement frequency. It should be understood that this step is a standard industry design and can be referenced according to industry requirements; this invention does not impose specific limitations on it.

[0087] (2) Survey line deployment: Design survey lines and survey points according to the detection target and survey area. Similarly, design according to the requirements of the application environment and with reference to industry standards.

[0088] (3) Device setup: Determine the number of observation points for each group based on the design and the number of instruments to be deployed. Synchronous observations can be conducted between each observation point. At each observation point, set up an electromagnetic field signal measuring device. Establish a spatial coordinate system Oxyz based on the measurement line and the observation point, with the origin O located at the observation point. The x-axis direction is chosen to be parallel to the measurement line direction, or it can be chosen to be due north or due east, while maintaining horizontality. The y-axis is perpendicular to the x-axis and horizontal. The z-axis is perpendicular to the xy plane and vertically downward. Arrange one on each of the positive and negative half-axis of the x-axis and the positive and negative half-axis of the y-axis. For measurements taken underground or in wells, a pair of non-polarized electrodes can be simultaneously arranged along the z-axis. The distance between the non-polarized electrodes and the origin is selected based on the required lateral resolution and site conditions, with a reference distance of 50m. This distance can be appropriately shortened when the elevation difference between the measurement points is large. The non-polarized electrodes must be buried at least 30cm in the soil. The magnetic field curl measuring device is placed at the origin, while the GPS antenna and signal receiver are placed near the observation point. The signal output lines of the non-polarized electrodes, the magnetic field curl measuring device, and the GPS are connected to the signal receiver.

[0089] (4) Data acquisition: Turn on the signal receiver and record the electric field components. , When measuring underground or in wells, the observation time and the location of the measuring point are recorded simultaneously; observation data are obtained through continuous acquisition over multiple cycles.

[0090] (5) Obtain the dielectric constant of the shallow layer through physical property measurement or ground penetrating radar, and for magnetic geological conditions, obtain the magnetic permeability data through magnetic exploration and other means; for non-magnetic geological conditions, use free space magnetic permeability.

[0091] (6) Data storage: Save the observation data; and calculate the corresponding total current wave impedance apparent resistivity according to the total current wave impedance apparent resistivity model which is not limited by quasi-static conditions, so as to realize real-time monitoring; turn off the measuring instrument and continue to perform the next set of measurements.

[0092] (7) Post-processing: Organize all collected data, perform data processing, invert graphs and interpret data.

[0093] When observing the electromagnetic field of an artificial source, the observation steps and receiving equipment are the same as those described above, while the selection and arrangement of the transmitting source are the same as those of the existing artificial source electromagnetic method.

[0094] As can be seen in Figures 1-5, the apparent resistivity of the full current wave impedance proposed in this invention does not exhibit the same downward drop as the apparent resistivity of Carnia in the high-frequency region. Analysis shows that this invention can effectively solve the problem of downward distortion of apparent resistivity caused by Carnia's apparent resistivity not meeting quasi-static conditions, thereby improving the accuracy of forward and inverse modeling and demonstrating the effectiveness of the method of this invention.

[0095] Specifically, Figure 1 (a) is a uniform half-space. A comparison of the apparent resistivity curves of the total current wave impedance (technical solution of this invention) and the apparent resistivity curves of Carnia. The apparent resistivity curve of Carnia. The graph shows the apparent resistivity curve of the total current wave impedance, with the horizontal axis representing frequency f and the vertical axis representing the apparent resistivity value. Figure 1 (b) shows the error curves of the apparent resistivity of the total current wave impedance and the apparent resistivity of Carnia in a real uniform half-space. The curves showing the apparent resistivity of Carnia versus the error of the uniform half-space are shown. The graph shows the apparent resistivity of the total current wave impedance versus the error curve in a uniform half-space, with the horizontal axis representing frequency f and the vertical axis representing the error value. From... Figure 1 Analysis (a) shows that in the uniform high-resistivity half-space model, the apparent resistivity curve of the full current wave impedance of the present invention has a much higher fitting degree with the resistivity of the real model over the entire frequency range (especially the high frequency band) than the traditional Carnia apparent resistivity. Figure 1Analysis (b) shows that, in the comparison of errors between the apparent resistivity of the total current wave impedance and the apparent resistivity of Carnia and the actual model values, the relative error of the apparent resistivity of the total current wave impedance of the present invention is consistently significantly lower than that of the apparent resistivity of Carnia in the high-frequency range of 10kHz to 1MHz. This indicates that the downward distortion of apparent resistivity caused by the non-compliance with the "quasi-static" assumption at high frequencies by the traditional Carnia apparent resistivity has been effectively suppressed by the new model proposed in this invention.

[0096] Figure 2 This is a comparison of the apparent resistivity of the total current wave impedance (technical solution of this invention) and the apparent resistivity curves of Carnia under different dielectric constants. (a) is a uniform half-space with a relative dielectric constant of 2 calculated using the actual relative dielectric constant of 2. (c) Comparison of apparent resistivity curves; (d) Calculation of relative permittivity using a true relative permittivity of 3. Comparison of apparent resistivity curves for a uniform half-space; (e) shows the calculation of a relative permittivity of 4 using a true relative permittivity of 4. Comparison of apparent resistivity curves in a uniform half-space The apparent resistivity curve of Carnia. The graph shows the apparent resistivity curve of Carnia, with the horizontal axis representing frequency f and the vertical axis representing the apparent resistivity value.

[0097] Figure 2 (b), (d), and (f) are the relative error curves of the apparent resistivity of the total current wave impedance (technical solution of this invention) and the apparent resistivity of Cania, respectively, compared with the real uniform half-space when the actual relative permittivity is 2, 3, and 4. The curves showing the apparent resistivity of Carnia versus the error of the uniform half-space are shown. The graph shows the apparent resistivity of the total current wave impedance versus the error curve of the uniform half-space, with the horizontal axis representing frequency f and the vertical axis representing the relative error value. From... Figure 2 It can be seen that in uniform half-space models with different dielectric constants, the accuracy of the apparent resistivity of the total current wave impedance of the present invention is better than that of the apparent resistivity of Carnia.

[0098] Figure 3 The graphs show a comparison of the apparent resistivity of the total current wave impedance (technical solution of this invention) and the apparent resistivity of Carnia under different permeabilities; (a) and (c) are uniform half-spaces with corresponding relative permeabilities calculated using actual relative permeabilities of 3 and 6. Comparison of apparent resistivity curves; The apparent resistivity curve of Carnia. The graph shows the apparent resistivity of the Carnia curve, with the horizontal axis representing frequency f and the vertical axis representing the apparent resistivity value.

[0099] Figure 3(b) and (d) are the error curves using apparent resistivity with actual relative permeability of 3 and 6, respectively, and actual uniform half-space. The curves showing the apparent resistivity of Carnia versus the error of the uniform half-space are shown. The graph shows the apparent resistivity of the total current wave impedance versus the error curve in a uniform half-space, with the horizontal axis representing frequency f and the vertical axis representing the error value. From... Figure 3 It can be seen that in uniform half-space models with different permeabilities, the apparent resistivity of the total current wave impedance of the present invention exhibits higher accuracy.

[0100] Figure 4 (a), (c), and (e) are the corresponding relative uniform half-spaces calculated using a true relative permeability of 3 and actual relative permittivity of 2, 3, and 4. Comparison of apparent resistivity curves; The apparent resistivity curve of Carnia. (RMT) is the Carnia apparent resistivity curve, with the horizontal axis representing frequency f and the vertical axis representing the apparent resistivity value.

[0101] Figure 4 (b), (d), and (f) are the error curves of the apparent resistivity calculated using a true relative permeability of 3 and actual relative permittivity of 2, 3, and 4, respectively, compared with the actual uniform half-space. The curve showing the relative error between the apparent resistivity of Carnia and the uniform half-space is shown. The graph shows the apparent resistivity of the total current wave impedance versus the error curve of the uniform half-space, with the horizontal axis representing frequency f and the vertical axis representing the relative error value. From... Figure 4 It can be seen that in complex uniform half-space models with different combinations of magnetism and dielectric constants, the apparent resistivity of the total current wave impedance of the present invention still maintains high accuracy.

[0102] Figure 5 (a) is a three-layer dielectric model (high-low-high resistance) H-type calculated using its true permeability and dielectric constant (subscripts 1, 2, 3 correspond to the first, second, and third dielectric layers, respectively). , , , ; , , , ; , For infinite values, , Comparison of resistivity curves The apparent resistivity curve of Carnia. The graph shows the apparent resistivity of the Carnia curve, with the horizontal axis representing frequency f and the vertical axis representing the apparent resistivity value. Figure 5(b) is the three-layer Q-type model calculated using its true permeability and permittivity. , , , ; , , , ; , For infinite values, , The present invention (total current wave impedance apparent resistivity) and the error curves of Carnia apparent resistivity versus a real uniform half-space, The curves showing the apparent resistivity of Carnia versus the error of the uniform half-space are shown. The graph shows the apparent resistivity of the total current wave impedance versus the error curve in a uniform half-space, with the horizontal axis representing frequency f and the vertical axis representing the error value. From... Figure 5 It can be seen that the apparent resistivity of the total current wave impedance of the present invention, compared with that of the Carnia apparent resistivity, significantly reduces the error with the response of the actual model across the entire frequency band, especially in the mid-to-high frequency band. This proves that the method of the present invention can still provide more reliable apparent resistivity data when characterizing non-uniform and complex layered geoelectric structures, laying a better data foundation for subsequent high-precision inversion interpretation.

[0103] In some embodiments, the present invention also provides a method for detecting underground electrical structures, such as... Figure 6 As shown, it includes the following steps:

[0104] The apparent resistivity of the total current wave impedance at the measuring point in the detection area is obtained by using the above-mentioned method for detecting the total current wave impedance, and then the apparent resistivity curve of each measuring point is obtained.

[0105] The apparent resistivity curve data of all measuring points can be used as observation data, and a three-dimensional resistivity structure model of the subsurface can be obtained by introducing a magnetotelluric inversion algorithm. Among them, OCCAM inversion and nonlinear conjugate gradient inversion can both be applied to the technical solution of this invention.

[0106] In practical detection applications, firstly, hardware acquisition units are deployed in the target area to simultaneously acquire the orthogonal electric field components and orthogonal magnetic field components at each measuring point, and to obtain the shallow surface dielectric constant and permeability. Then, the total current wave impedance at each measuring point at each frequency is calculated, and the apparent resistivity model algorithm for total current wave impedance is applied, combined with... , , The parameters are used to calculate the apparent resistivity curves for each measuring point. Finally, the apparent resistivity curve data of all measuring points can be used as observation data and introduced into existing magnetotelluric inversion algorithms (such as OCCAM inversion, nonlinear conjugate gradient inversion, etc.) to obtain a three-dimensional resistivity structure model of the subsurface, thereby achieving high-precision detection of the subsurface electrical structure.

[0107] In some embodiments, the present invention also provides a detection system, which includes a detection device, a data processing unit, and a power supply unit that work together:

[0108] The detection equipment includes electric field sensors, magnetic field sensors, physical testing elements, and a GPS / BeiDou-based positioning and synchronization module deployed within the detection area. The electric field sensors detect electric field data, the magnetic field sensors detect magnetic field data (magnetoresistive / inductive magnetometers, frequency coverage 0~1MHz), and the physical testing elements (ground penetrating radar, dielectric constant meter, permeability meter, etc.) obtain the dielectric constant of the shallow surface layer. and permeability The positioning and synchronization module provides the coordinates of the measurement points and ensures synchronous acquisition of multiple measurement points. The data processing unit includes a signal receiver and a computer terminal. The signal receiver is connected to the detection equipment to acquire the detection data and transmit it to the computer terminal (equipped with a full current wave impedance apparent resistivity algorithm for real-time / offline calculation of apparent resistivity). Specifically, the computer terminal uses the detection data to calculate the full current wave impedance apparent resistivity at the measurement point through a full current wave impedance apparent resistivity model that is not limited by quasi-static conditions. The power supply unit provides power to the hardware of the detection system.

[0109] In some embodiments, the present invention also provides a computer terminal, comprising: one or more processors and a memory storing one or more computer programs; wherein the processor invokes the computer programs to implement: the steps of a method for detecting apparent resistivity of a total current wave impedance. Specifically:

[0110] Acquire detection data, including the orthogonal electric and magnetic field components obtained from measurement points within the detection area; and obtain the dielectric constant of the shallow surface layer. and permeability The measurement point uses a sensor with a frequency range covering 1MHz for detection; using the detection data, the apparent resistivity of the total current wave impedance at the measurement point is calculated through a total current wave impedance apparent resistivity model that is not limited by quasi-static conditions.

[0111] The processor can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present invention.

[0112] The memory can be implemented in the form of read-only memory (ROM), static storage device, dynamic storage device, or random access memory (RAM). The memory can store the operating system and other applications. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory and the processor calls and executes the algorithm program of the detection method of the embodiments of this invention.

[0113] In some embodiments, the present invention also provides a computer-readable storage medium including a computer program, which is invoked by a processor to implement the steps of a method for detecting apparent resistivity of a total current wave impedance. Specifically:

[0114] Acquire detection data, including the orthogonal electric and magnetic field components obtained from measurement points within the detection area; and obtain the dielectric constant of the shallow surface layer. and permeability The measurement point uses a sensor with a frequency range covering 1MHz for detection; using the detection data, the apparent resistivity of the total current wave impedance at the measurement point is calculated through a total current wave impedance apparent resistivity model that is not limited by quasi-static conditions.

[0115] Please refer to the explanation of the method above for the specific implementation process of each step.

[0116] The readable storage medium is a computer-readable storage medium, which can be an internal storage unit of the hardware and software device described in any of the foregoing embodiments, such as the hard drive or memory of the controller. The readable storage medium can also be an external storage device of the controller, such as a plug-in hard drive, Smart MediaCard (SMC), Secure Digital (SD) card, or Flash Card equipped on the controller. Further, the readable storage medium can include both internal storage units and external storage devices of the controller. The readable storage medium is used to store the computer program and other programs and data required by the controller. The readable storage medium can also be used to temporarily store data that has been output or will be output.

[0117] Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer terminal (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned readable storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0118] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-readable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. This application refers to flowchart illustrations and / or instructions executed by a processor of a method, apparatus (system), and computer program product according to embodiments of this application to create means for implementing the functions specified in one or more flowchart illustrations and / or one or more block diagrams. These computer program instructions may also be stored in a computer-readable storage medium capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowchart illustrations and / or one or more block diagrams. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more blocks of a block diagram.

[0119] It should be emphasized that the examples described in this invention are illustrative rather than limiting. Therefore, this invention is not limited to the examples described in the specific embodiments. Any other embodiments derived by those skilled in the art based on the technical solutions of this invention, without departing from the spirit and scope of this invention, whether modifications or substitutions, are also within the protection scope of this invention.

Claims

1. A method for detecting apparent resistivity of total current wave impedance, characterized in that: The application of radio frequency magnetotelluric (RFT) includes the following steps: Data is collected by deploying sensors at measurement points within the detection area to obtain orthogonal electric and magnetic field components, as well as the dielectric constant of the shallow surface layer. and permeability ; Using the detection data, the apparent resistivity of the total current wave impedance at the measuring point is calculated through a total current wave impedance apparent resistivity model that is not limited by quasi-static conditions, and the detection results of the apparent resistivity of the total current wave impedance in the detection area are obtained. The apparent resistivity model of the total current wave impedance, which is not subject to quasi-static conditions, is as follows: ； In the formula, To obtain the apparent resistivity of the total current wave impedance for RMT (Remote Radio Frequency Magnetism) For total current impedance, Angular frequency, Where is the dielectric constant. is the magnetic permeability.

2. The method according to claim 1, characterized in that: The total current wave impedance is determined based on the orthogonal electric and magnetic field components in the detection data, satisfying the following: TE mode: Total current impedance The corresponding representation is : , Indicates electric field strength In a spatial rectangular coordinate system The directional component, i.e., the electric field along the x-direction; Indicates magnetic field strength In a spatial rectangular coordinate system The directional component, i.e., the magnetic field along the y-direction; TM Mode: Total Current Surge Impedance The corresponding representation is : , Indicates electric field strength The y-direction component in a spatial rectangular coordinate system, i.e., the electric field along the y-direction; Indicates magnetic field strength The x-direction component in a spatial rectangular coordinate system, i.e., the magnetic field along the x-direction.

3. The method according to claim 1, characterized in that: Under low-frequency conditions, neglecting displacement current, the dielectric constant of the shallow layer is... Setting it to 0 corresponds to the parameter used for the apparent resistivity of the total current wave impedance at the measuring point. express: .

4. The method according to claim 1, characterized in that: The electric and magnetic fields measured in the detection area are electromagnetic fields generated by natural electromagnetic fields or artificial field sources, and are applicable to 1-3 multi-dimensional scenarios.

5. The method according to claim 1, characterized in that: The frequency range of the sensors deployed at the measuring points covers 1MHz.

6. A method for detecting underground electrical structures, characterized in that: Includes the following steps: The apparent resistivity of the total current wave impedance at the measuring point in the detection area is obtained by using the total current wave impedance apparent resistivity detection method according to any one of claims 1-5, and then the apparent resistivity curve of each measuring point is obtained. The apparent resistivity curve data of all measuring points can be used as observation data, and the magnetotelluric inversion algorithm can be introduced to obtain the three-dimensional resistivity structure model of the underground, thus completing the detection of the underground electrical structure of the detection area.

7. A detection system based on the method of any one of claims 1-5, characterized in that: This includes collaborative detection equipment, data processing units, and power supply units: The detection equipment includes an electric field sensor, a magnetic field sensor, physical testing elements, and a GPS / BeiDou-based positioning and synchronization module deployed within the detection area. The electric field sensor detects electric field data, the magnetic field sensor detects magnetic field data, and the physical testing elements acquire the dielectric constant of the shallow surface layer. and permeability The positioning synchronization module is used to provide the coordinates of the measuring points and ensure synchronous acquisition of multiple measuring points. The data processing unit includes a signal receiver and a computer terminal. The signal receiver is communicatively connected to the detection device to acquire detection data and transmit it to the computer terminal. The computer terminal uses the detection data to calculate the apparent resistivity of the total current wave impedance at the measurement point using a total current wave impedance apparent resistivity model that is not limited by quasi-static conditions. The power supply unit provides power to the hardware of the detection system.

8. A computer terminal, characterized in that: Includes one or more processors; A memory that stores one or more computer programs; The processor invokes a computer program to achieve the following: The steps of the method for detecting apparent resistivity of a full current wave impedance as described in any one of claims 1-5.

9. A computer-readable storage medium, characterized in that: Includes a computer program, which is invoked by a processor to implement: The steps of the method for detecting apparent resistivity of a full current wave impedance as described in any one of claims 1-5.

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