Ground-air wide-area electromagnetic method response extraction method and system based on horizontal total magnetic field

Abstract

The invention discloses a ground-air wide-area electromagnetic method response extraction method and system based on a horizontal total magnetic field, and the method proposes rotation invariance of the horizontal total magnetic field, so that a ground emission source is arranged outside a measurement area, and a magnetic field sensor receiving device is carried in the air above the measurement area through a flight platform; the horizontal magnetic field data acquisition module is used for acquiring / acquiring two-component horizontal magnetic field data as horizontal magnetic field observed quantity of an observation point and further used for calculating horizontal total magnetic field observed quantity; and then, based on the rotation invariance of the horizontal magnetic total field, constructing an inversion target function with the difference value between the response quantity of the horizontal magnetic total field and the observed quantity of the horizontal magnetic total field tending to be 0, and iteratively solving the inversion target function to obtain the inversion target quantity of the measured area so as to realize physical exploration. According to the technical scheme, a brand new ground-air wide-area electromagnetic measurement scheme is provided by utilizing rotation invariance of a horizontal total magnetic field, the influence of attitude errors is effectively solved, and observation and response extraction which is suitable for aviation frequency domain electromagnetic field observation and is slightly influenced by the attitude errors is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic exploration signal processing, and in particular relates to a method and system for extracting ground-to-air wide-area electromagnetic responses based on the horizontal total magnetic field. Background Art

[0002] Wide-field electromagnetic (WFE) is a new artificial source frequency-domain electromagnetic method developed in recent years. It features deep exploration depths, high detection accuracy, and strong anti-interference capabilities. Currently, WFE has been successfully applied in a variety of resource exploration fields, including metal minerals, shale gas, and oil and gas. However, conventional ground-based WFE is susceptible to interference from terrain, making it difficult to implement in the field. In recent years, drone technology has matured, and the field of airborne electromagnetics has also gradually developed. Airborne wide-field electromagnetic (AFE) combines the advantages of high-power transmission from ground-based electromagnetic methods with the rapid, non-contact, and continuous acquisition capabilities of airborne electromagnetic methods, offering the potential for rapid exploration over large depths in areas with complex surface conditions. Frequency-domain AFE is widely used in geological mapping, water resource surveys, and urban underground space exploration.

[0003] However, in geophysical exploration, airborne electromagnetic methods (AEM) are susceptible to factors such as flight speed, aircraft turbulence, wind speed, and wind direction during flight. This can alter the coupling between the transceiver coils and the ground being measured, leading to attitude errors. These attitude errors can significantly impact the quality of airborne electromagnetic data, necessitating the development of observation and response extraction technologies suitable for airborne frequency-domain electromagnetic field observations that are less susceptible to attitude errors. Summary of the Invention

[0004] Based on the shortcomings and deficiencies in the above-mentioned prior art, the present invention aims to develop an observation technology solution that is less affected by attitude errors, so as to solve the problem of attitude error influence in frequency domain airborne electromagnetic observation and improve the quality of response extraction.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] On the one hand, the technical solution of the present invention provides a method for extracting ground-to-air wide-area electromagnetic responses based on the horizontal total magnetic field, comprising the following steps:

[0007] S1. Set up a ground transmitting source outside the measurement area, and use a flying platform to carry a magnetic field sensor receiving device in the air above the measurement area to collect / acquire two-component horizontal magnetic field data as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal magnetic field observation quantity;

[0008] S2. Based on the rotational invariance of the horizontal total magnetic field, an inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation approaching 0, and the inversion objective function is iteratively solved to obtain the inversion target quantity of the survey area;

[0009] The horizontal magnetic total field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal magnetic total field response of the observation point.

[0010] Preferably, the rotation invariance of the horizontal total magnetic field is: when the magnetic field sensor shakes in the horizontal direction and the rotation angle of the magnetic field sensor changes, the single component value of the horizontal magnetic field and will change, but the horizontal total magnetic field remains unchanged, that is, the horizontal total magnetic field response is not affected by the attitude rotation angle.

[0011] Preferably, the inversion objective function is expressed as:

[0012] ;

[0013] Where, is the inversion objective function value, and Perform iterative solution, is the total horizontal magnetic field response, is the total horizontal magnetic field observation quantity, is the inversion target quantity.

[0014] Preferably, a dichotomy is used Perform iterative solution, the specific process is:

[0015] For inversion target quantity Set the value range And set the iteration termination condition;

[0016] calculate Is it less than 0? If it is less than 0, take and calculate Otherwise, adjust the value range ;

[0017] according to Less than 0 or Less than 0, corresponding to a narrowed value range for or ;

[0018] Determine whether the iteration termination condition is met. If so, obtain the inversion target quantity based on the current value interval; otherwise, continue to take the median value to narrow the value interval and proceed to the next round of iteration.

[0019] Preferably, the theoretical equation for the total horizontal magnetic field response is: = , is the total horizontal magnetic field response, 、 are the horizontal magnetic field components in the x and y directions respectively, is the inversion target quantity;

[0020] Among them, in layered media, the expression of the horizontal magnetic field component value received by the aerial observation point after the ground transmission source transmits is:

[0021] ;

[0022] ;

[0023] Under the uniform half-space model, the expression of the horizontal magnetic field component value received by the aerial observation point after the ground transmission source is transmitted is:

[0024] ;

[0025] ;

[0026] Where I is the magnitude of the current injected into the ground by the source outside the measurement area, ds is the length of the dipole, r is the transmitting and receiving distance, that is, the distance between the ground source and the observation point projected onto the geodetic coordinate system, x, y, and z are the coordinates of the observation point, the z direction is vertically downward, the coordinates of the electric dipole are (0, 0, -h), and h is the height from the ground; is the integral term of the Bessel function, and are zero-order and first-order Bessel functions, respectively, with parameters ,parameter , is the magnetic permeability in vacuum, is the circular frequency, and are the resistivities in the air layer and the first underground medium, respectively; is the reflection coefficient of the TM mode, is the reflection coefficient of the TE mode.

[0027] Preferably, the inversion target quantity is resistivity.

[0028] In a second aspect, the technical solution of the present invention provides a device based on the ground-to-air wide-area electromagnetic method response extraction method, which comprises at least a ground transmitting source arranged outside the measurement area, a flying platform arranged in the air above the measurement area, and a magnetic field sensor receiving device carried by the flying platform;

[0029] Wherein, the ground transmitting source adopts grounded galvanic source excitation to transmit electromagnetic waves of different frequencies;

[0030] The magnetic field sensor receiving device receives magnetic field data and transmits it to the built-in controller or the external controller connected by communication so that the controller calculates the inversion target quantity according to the magnetic field data in the manner of step S2.

[0031] In a third aspect, the technical solution of the present invention provides a system based on the ground-air wide-area electromagnetic method response extraction method, comprising:

[0032] The magnetic field data acquisition module is used to collect / acquire the two-component horizontal magnetic field data of the aerial measurement point as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal magnetic field total field observation quantity;

[0033] The processing module is used to construct an inversion objective function based on the rotation invariance of the horizontal total magnetic field and the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tends to 0, and iteratively solve the inversion objective function to obtain the inversion target quantity of the survey area;

[0034] The horizontal magnetic total field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal magnetic total field response of the observation point.

[0035] In a fourth aspect, the technical solution of the present invention provides an electronic device, comprising: one or more processors and a memory storing one or more computer programs;

[0036] The processor calls a computer program to implement:

[0037] Collect / acquire two-component horizontal magnetic field data of the aerial measuring point as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal magnetic field observation quantity. The two-component horizontal magnetic field data of the aerial measuring point is obtained by using a ground-based transmitting source set up outside the measurement area and a magnetic field sensor receiving device mounted on a flying platform in the air above the measurement area;

[0038] Based on the rotation invariance of the horizontal total magnetic field, the inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tending to 0. The inversion target quantity of the survey area is obtained by iteratively solving the inversion objective function.

[0039] The horizontal magnetic total field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal magnetic total field response of the observation point.

[0040] In a fifth aspect, the technical solution of the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program is called by a processor to implement:

[0041] Collect / acquire two-component horizontal magnetic field data of the aerial measuring point as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal magnetic field observation quantity. The two-component horizontal magnetic field data of the aerial measuring point is obtained by using a ground-based transmitting source set up outside the measurement area and a magnetic field sensor receiving device mounted on a flying platform in the air above the measurement area;

[0042] Based on the rotation invariance of the horizontal total magnetic field, the inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tending to 0. The inversion target quantity of the survey area is obtained by iteratively solving the inversion objective function.

[0043] The horizontal magnetic total field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal magnetic total field response of the observation point.

[0044] Beneficial effects:

[0045] The present invention proposes and demonstrates the rotational invariance of the horizontal total magnetic field, that is, when the magnetic field sensor shakes in the horizontal direction, causing the attitude rotation angle to change, the horizontal total magnetic field remains unchanged, and the magnetic field response of the horizontal total magnetic field is not affected by the change in the rotation angle of the magnetic field sensor caused by the shaking of the magnetic field sensor in the horizontal direction. Furthermore, the technical solution of the present invention uses this new conclusion to propose a new ground-to-air wide-area electromagnetic method response extraction method based on the horizontal total magnetic field. Specifically, for scenarios where ground-based transmission sources and magnetic field data are collected in the air, an inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation approaching 0. Finally, the inversion objective function is iteratively solved to obtain the inversion target quantity of the survey area. This method effectively avoids the influence of attitude errors caused by coil rotation on the data, ensuring the quality of response extraction.

[0046] The technical solution of the present invention provides a method for extracting the ground-to-air wide-area electromagnetic response based on the horizontal total magnetic field, which has a wide range of applicability. It solves the technical defects caused by attitude problems in flight detection through a simple and efficient method without changing the original hardware facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1This is a schematic diagram of a ground-to-air wide-area electromagnetic method device provided by an embodiment of the present invention, wherein source is a ground field source, survey area is the survey area, ground surface is the ground, and receiver and sensor in the air are the flight platform and the aerial magnetic field sensor.

[0049] Figure 2 It is a schematic diagram of the two components of the horizontal magnetic field when the ground-to-air wide-area sensor provided by an embodiment of the present invention is swinging.

[0050] Figure 3 This is a diagram of the apparent resistivity calculation scheme of the ground-to-air wide-area electromagnetic method provided by an embodiment of the present invention, wherein (a), (b), (c), and (d) are respectively 、 、 and the horizontal total magnetic field Field value radiation pattern diagram.

[0051] Figure 4 This is a radiation pattern provided by an embodiment of the present invention.

[0052] Figure 5 This is a characteristic curve diagram of the total horizontal magnetic field response of the uniform half-space model provided by an embodiment of the present invention.

[0053] Figure 6 This is a comparison diagram of the total horizontal magnetic field and the four-component apparent resistivity response observed on the ground provided by an embodiment of the present invention.

[0054] Figure 7 This is a comparison diagram of the horizontal magnetic total field apparent resistivity response curves under different field quantity observation angle conditions provided by an embodiment of the present invention. (a) corresponds to the layered medium H-type model, and (b) corresponds to the uniform half-space model.

[0055] Figure 8 These are analysis diagrams of the apparent resistivity responses of the horizontal total magnetic field and the two components of the magnetic field under the conditions of attitude error and absence of aerial observation provided by an embodiment of the present invention. Figures (a) and (c) are analysis diagrams corresponding to the uniform half-space model and the layered medium H-type model when there is no attitude error angle, respectively. Figures (b) and (d) are analysis diagrams corresponding to the uniform half-space model and the layered medium H-type model when there is an attitude error angle, respectively.

[0056] Figure 9 The present invention provides a schematic diagram of hardware components in an electronic terminal. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not intended to limit the present invention. The technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0058] It should be noted that although the device schematics illustrate functional module divisions and the flowcharts illustrate logical sequences, in certain circumstances, the steps shown or described may be performed in a sequence that differs from the module divisions in the device or the sequence in the flowcharts. The terms "first," "second," and so on, in the specification, claims, and drawings, are used to distinguish similar items and are not necessarily used to describe a specific sequence or precedence.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0060] This invention addresses the problem that airborne electromagnetic (AEM) observations are susceptible to attitude errors during flight, influenced by factors such as flight speed, aircraft turbulence, wind speed, and wind direction. This attitude error significantly impacts the quality of frequency-domain airborne electromagnetic observations. By providing a method for extracting wide-area ground-to-air electromagnetic responses based on the horizontal total magnetic field, this invention explores and verifies the rotational invariance of the horizontal total magnetic field. Based on this principle, it proposes an observation and response extraction technique suitable for airborne frequency-domain electromagnetic field observations that is less susceptible to attitude errors. The invention will be described in detail below with reference to specific examples.

[0061] In order to facilitate a better understanding of the embodiments of the present invention, before explaining the specific embodiments of the present invention in detail, its application scenarios are first described.

[0062] Figure 1Shown is a schematic diagram of the ground-to-air wide-area electromagnetic method device. The ground-to-air wide-area electromagnetic method uses an underground transmitting source to transmit signals and collect data in the air. The collection device is set in the air with the help of a flying platform. The device has the dual advantages of high-power transmission of the ground wide-area electromagnetic method and fast non-contact continuous collection of the airborne electromagnetic method. Unlike the conventional ground wide-area electromagnetic method, the ground-to-air wide-area electromagnetic method is easily affected by factors such as flight speed, wind speed, drone interference, and flight altitude in actual work projects, resulting in the introduction of various noises. Among them, the impact caused by attitude error has always been a major problem of the ground-to-air wide-area electromagnetic method, especially when the magnetic field sensor shakes in the horizontal direction, causing the rotation angle of the magnetic field sensor to change. In order to solve this problem, the present invention provides a new ground-to-air wide-area electromagnetic measurement solution.

[0063] For this reason, the present invention carries out the following theoretical research:

[0064] Starting from Maxwell's equations:

[0065] (1).

[0066] in, represents the electric field, is the magnetic field, is the angular frequency, is the magnetic permeability, Indicates conductivity. The conductivity and thickness of each layer are set as .

[0067] In layered media, after the ground-based transmitter emits, the three-component expression of the magnetic field received by the aerial magnetic field sensor at the measuring point is:

[0068] (2).

[0069] (3).

[0070] (4).

[0071] Where I is the magnitude of the current injected into the ground by the source outside the measurement area, ds is the length of the dipole, r is the transmitting-receiving distance, that is, the distance between the ground source outside the measurement area and the flight platform (observation point) projected onto the geodetic coordinate system, x, y, and z are the coordinates of the observation point, which is the position of the receiving coil during the flight of the flight platform. The z direction is vertically downward, and the coordinates of the electric dipole are (0, 0, -h), and h is the height from the ground. is the integral term of the Bessel function, and are zero-order and first-order Bessel functions, respectively, with parameters ,parameter , is the magnetic permeability in vacuum, is the circular frequency, and are the resistivities in the air layer and the first underground medium, respectively; is the reflection coefficient of the TM mode (Transverse Magnetic Mode). The TM mode uses the Shekunoff potential. express, is the reflection coefficient of the TE mode (Transverse Electric Mode, transverse electric field mode), and the TE mode is represented by the vector potential Indicates that, in the perpendicular magnetic field expression, The integral part represents the primary field generated by the wire. The integral part represents the secondary field induced by the earth medium. The integral part represents the secondary field generated by the underground medium in the air layer; H y In the expression, Represents the primary field generated by the wire. H x The primary field generated by the wire does not exist in the expression.

[0072] By averaging the source height h and the observation location z in the magnetic field expression above the electric dipole to zero, we obtain an expression for the electric dipole and the receiving point located at the ground, which agrees with existing ground-based expressions. The calculation of the three components of the magnetic field ultimately involves a Hankel transform. The present invention employs numerical integration combined with extrapolation for high-precision calculations.

[0073] For the case of uniform half space, the above formula can be simplified to:

[0074] (5).

[0075] Further let h=0, = The three-component expression of the magnetic field at the aerial measuring point in the uniform half space can be derived. Compared with the representation of the magnetic field on the ground, the difference is that there is an additional , which reflects the attenuation of the electromagnetic field from the ground to the air in the wave number domain. The specific formula is as follows:

[0076] (6). (7).

[0077] (8).

[0078] From this, we can get the three components of the magnetic field in the layered medium and uniform half-space model 、 、 The magnetic field response formula is used to calculate the magnetic field response of the wide-area electromagnetic field in the ground and air, and further calculate the wide-area apparent resistivity of the magnetic field. Subsequently, the magnetic field response can be directly inverted, or the wide-area apparent resistivity can be inverted to obtain electrical information about the underground medium and complete electromagnetic profiling or depth sounding.

[0079] The core of this invention lies in the rotational invariance of the horizontal total magnetic field: when the sensor is shaken horizontally, causing the rotation angle to change, the horizontal total magnetic field remains unchanged. In other words, the horizontal total magnetic field response is unaffected by the attitude rotation angle. This rotational invariance of the horizontal total magnetic field is demonstrated as follows:

[0080] The total horizontal magnetic field expression is:

[0081] (9).

[0082] When the magnetic field sensor has an attitude error, the two components of the horizontal magnetic field measured by the magnetic field sensor are recorded as and :

[0083] (8).

[0084] (10).

[0085] like Figure 2 As shown, and are the angles formed by the magnetic field sensor and the x-axis and y-axis when there is an attitude error.

[0086] When the attitude error is considered, the total horizontal magnetic field is expressed as :

[0087] = = (11).

[0088] In practice, the rotation angle = ,Right now:

[0089] = (12).

[0090] Therefore, it can be seen that when the sensor shakes horizontally and the rotation angle changes, the horizontal total magnetic field remains unchanged, that is, the horizontal total magnetic field response is not affected by the posture rotation angle. In this embodiment, the magnetic field sensor can be manufactured as a fixed orthogonal structure.

[0091] Based on the rotation invariance of the horizontal total magnetic field, the horizontal total magnetic field is used for inversion calculation, which can effectively avoid the influence of attitude error. And the present invention can know through analysis that, relative to the two components of the horizontal magnetic field, the horizontal total magnetic field The observable area is larger, so the horizontal total magnetic field is selected Taking measurements can achieve better results in the field, as follows:

[0092] like Figure 3 As shown, this embodiment provides a magnetic field radiation pattern diagram under aviation measurement conditions. Figure 3 In the figure, x and y are the emission frequencies, is the skin depth, and sub-figures (a), (b), (c), and (d) are 、 、 and the horizontal total magnetic field The field value radiation pattern diagram. It can be seen from the figure that the horizontal magnetic field component field value The radiation pattern shows an "X" shape, with a maximum value at an angle of 45° to the x-axis, and a zero band value under axial and equatorial observation devices. The radiation pattern shows a "cross" shape, with maximum values ​​under the axial and equatorial observation devices, and the field changes slowly in the equatorial region. When the angle with the x-axis is 45°, the field value amplitude has a zero band value. It is divided into two lobes by the x-axis and presents a minimum value in the axial area. As the transmitting and receiving distance increases, it can be seen that the magnetic field signal intensity decreases significantly. Only in the vertical device is the magnetic field signal intensity larger. Quantity and 、 Compared with the component field values, in the same area The component magnetic field signal strength is much weaker than the horizontal magnetic field component and , and the observation range is small. The field value amplitude is large in any direction, and there is no zero band value. The observable area is larger, so the horizontal total magnetic field is selected Taking measurements can achieve better results during field work.

[0093] In addition, if Figure 4 As shown, this embodiment gives the characteristic curve of the horizontal magnetic field response of the uniform half-space model. Establish a uniform half-space, the transmitting pole distance is 2000m, the current is 20A, the receiving and transmitting distance is 3000m, and when there is an attitude error: the rotation angle = =10°. The responses of the horizontal total magnetic field for two different models with and without attitude errors are discussed and analyzed. The figure shows that the characteristic curves of the horizontal total magnetic field response before and after rotation completely overlap, indicating that the presence or absence of attitude errors has no effect on the horizontal total magnetic field, verifying the correctness of the theory of rotational invariance of the horizontal total magnetic field.

[0094] Based on the above theoretical analysis, in some embodiments, the present invention provides a method for extracting ground-to-air wide-area electromagnetic responses based on the horizontal total magnetic field, comprising the following steps:

[0095] S1. Set up a ground transmitting source outside the measurement area, and use a flying platform to carry a magnetic field sensor receiving device in the air above the measurement area to collect / acquire two-component horizontal magnetic field data as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal total magnetic field observation quantity.

[0096] In some embodiments, a magnetic field sensor is used to obtain two-component horizontal magnetic field time domain data, and then the two-component horizontal magnetic field time domain data is Fourier transformed into frequency domain data. 、 , and then calculate the horizontal total magnetic field based on formula (9) , that is, the horizontal total magnetic field observation quantity.

[0097] S2. Based on the rotational invariance of the horizontal total magnetic field, the inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tending to 0, and the inversion target quantity of the survey area is obtained by iteratively solving the inversion objective function.

[0098] In this embodiment, the inversion target quantity is the wide-area apparent resistivity of the magnetic field. In other feasible embodiments, the inversion target quantity can also be other physical parameters of the underground medium, such as magnetic susceptibility. This invention is not specifically limited to this. The wide-area apparent resistivity of the magnetic field is used as an example to illustrate the technical concept and implementation process of the technical solution of the present invention.

[0099] Due to the rotational invariance of the horizontal total magnetic field, the difference between the horizontal total magnetic field response calculated based on the theory and the horizontal total magnetic field observation calculated based on the actual magnetic field data should be close to 0. Therefore, in some embodiments, the following inversion objective function is directly constructed:

[0100] (13).

[0101] Where, is the inversion objective function value, and Perform iterative solution, is the total horizontal magnetic field response, is the total horizontal magnetic field observation quantity, is the inversion target quantity.

[0102] In other embodiments, the inversion objective function constructed under the characteristic that the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tends to 0 also meets the requirements of the technical solution of the present invention and falls within the protection scope of the present invention, that is, formula (13) is deformed under the characteristic that the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tends to 0.

[0103] when is the wide-area apparent resistivity of the magnetic field, assuming that the underground medium has a resistivity equal to The uniform half space, the total horizontal magnetic field at the measuring point can be estimated as:

[0104] = (14).

[0105] in, 、 are the horizontal magnetic field component values ​​calculated according to formulas (6) and (7), respectively.

[0106] Take the objective function:

[0107] (15).

[0108] Where, is the objective function defined according to formula (15), is the total horizontal magnetic field observation value, For The total horizontal magnetic field response at the measuring point is calculated according to formula (14) for a uniform half-space with background resistivity, and the following formula is iteratively solved:

[0109] (16).

[0110] The resistivity that satisfies formula (16) is the wide-area apparent resistivity of the Earth-to-air wide-area electromagnetic method based on the horizontal total magnetic field.

[0111] like Figure 5 As shown, this embodiment provides a flow chart of calculating the wide-area apparent resistivity of the ground-air wide-area electromagnetic method based on the horizontal total magnetic field. In this embodiment, the binary method is selected to calculate the wide-area apparent resistivity of the ground-air wide-area electromagnetic method based on the horizontal total magnetic field. Perform iterative solution, the specific process is:

[0112] For inversion target quantity Set the value range And set the iteration termination condition;

[0113] calculate Is it less than 0? If it is less than 0, take and calculate Otherwise, adjust the value range ;

[0114] according to Less than 0 or Less than 0, corresponding to a narrowed value range for or ;

[0115] Determine whether the iteration termination condition is reached. If so, obtain the inversion target value based on the current value range. (This is achievable with existing technology, and adaptive technical adjustments can be made based on accuracy); otherwise, continue to take the median to narrow the value range and proceed to the next round of iteration.

[0116] It should be understood that the above technical means are also applicable to other inversion target quantities other than resistivity.

[0117] like Figure 6 As shown in Figure 1, this example provides a comparison of the total horizontal magnetic field and the four-component apparent resistivity response under ground observation conditions. A uniform half-space model was established with a transmitting current of 20A and a transmitting moment of 1000m. The figure shows that under ground observation conditions, the total horizontal magnetic field and the four-component apparent resistivity responses are consistent, accurately reflecting the underground medium conditions and demonstrating the reliability of the apparent resistivity calculated using the total horizontal magnetic field.

[0118] like Figure 7 As shown, this embodiment provides curves of the horizontal total magnetic field apparent resistivity response under the conditions of a layered medium model and a uniform half-space model with and without attitude error. In the figure, subgraph (a) shows the horizontal total magnetic field apparent resistivity response under the layered medium H-type model, and subgraph (b) shows the horizontal total magnetic field apparent resistivity response under the uniform half-space model. It can be seen that under both models, the presence or absence of attitude error has no impact on the apparent resistivity calculated from the horizontal total magnetic field. The apparent resistivity response remains unchanged, effectively reflecting information about the subsurface medium.

[0119] like Figure 8 As shown, this embodiment provides an analysis diagram of the apparent resistivity response of the horizontal total magnetic field and the two components of the magnetic field under the conditions of airborne observation with and without attitude error. In the figure, sub-graphs (a) and (c) are the angles without attitude error, that is, = =0°, the apparent resistivity responses of the horizontal total magnetic field and the two components of the magnetic field under the conditions of the uniform half-space model and the layered medium H-type model; sub-figures (b) and (d) are respectively when there is an attitude error angle, that is, = =10°, the apparent resistivity responses of the horizontal total magnetic field and the two components of the magnetic field under the conditions of the uniform half-space model and the layered medium H-type model; it can be seen from the figure that when there is no attitude error, the horizontal total magnetic field and the magnetic field observed in the air 、 The components can effectively reflect the underground medium conditions. However, when the sensor has attitude errors, and The apparent resistivity response curve calculated by the component is distorted to a certain extent and fails to reflect the real underground medium information. Under the condition of uniform half-space model, and The component is obviously distorted in the low-frequency part, and the apparent resistivity also changes in magnitude; however, under the two typical model conditions, the shape of the horizontal total magnetic field apparent resistivity curve does not change, and it still has the ability to reflect the real underground situation.

[0120] In summary, the method for extracting the ground-to-air wide-area electromagnetic response of the horizontal total magnetic field proposed in the technical solution of the present invention can effectively avoid the influence of attitude errors, and the extracted responses can truly reflect the underground medium information, proving the reliability and effectiveness of this method.

[0121] In some embodiments, the technical solution of the present invention also provides a device based on the ground-to-air wide-area electromagnetic method response extraction method, which at least includes a ground transmitting source arranged outside the survey area, a flying platform arranged in the air above the survey area, and a magnetic field sensor receiving device carried on the flying platform; wherein, the ground transmitting source adopts a grounded electric dipole source excitation to send electromagnetic waves of different frequencies; the magnetic field sensor receiving device receives the magnetic field data and transmits it to a built-in controller or an external controller connected by communication so that the controller calculates the inversion target quantity according to the magnetic field data in accordance with step S2.

[0122] It should be understood that the above embodiments are analyzed from the perspective of hardware components. Regarding the controller, in some embodiments, the controller can be internally connected to the magnetic field sensor, receive magnetic field data, and then perform an algorithm calculation according to step S2 to invert the target quantity. In other embodiments, the controller can be externally connected to a remote communication, receive magnetic field data, and then perform an algorithm calculation according to step S2 to invert the target quantity.

[0123] In some embodiments, the technical solution of the present invention also provides a system based on the ground-to-air wide-area electromagnetic method response extraction method, including: a magnetic field data acquisition module and a processing module.

[0124] The magnetic field data acquisition module collects two-component horizontal magnetic field data from an aerial survey point, which serves as the horizontal magnetic field observation at the observation point and is used to calculate the total horizontal magnetic field observation. The processing module constructs an inversion objective function based on the rotational invariance of the total horizontal magnetic field, assuming the difference between the total horizontal magnetic field response and the observed horizontal magnetic field tends to zero. This inversion objective function is then iteratively solved to obtain the inversion target quantity for the survey area. The total horizontal magnetic field response is calculated by substituting the set inversion target quantity into the theoretical equation for the total horizontal magnetic field response at the observation point.

[0125] It should also be understood that the specific implementation process of each module please refer to the above method content, the present invention will not go into details here, and the division of the above functional modules is only for illustration. In some embodiments, some functional modules can be merged, and some functional modules can be split. Each functional module can be implemented in software or hardware or a combination of software and hardware. Among them, the software and hardware equipment includes but is not limited to general electronic terminals, programmable gate arrays, digital signal processors, microprocessors and their corresponding programming or burning software.

[0126] In some embodiments, the technical solution of the present invention further provides an electronic device, comprising: one or more processors and a memory storing one or more computer programs; wherein the processor calls the computer program to implement:

[0127] The two-component horizontal magnetic field data of the aerial measuring point are collected / obtained as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal total magnetic field observation quantity. The two-component horizontal magnetic field data of the aerial measuring point are obtained by setting up a ground transmitting source outside the measuring area and using a magnetic field sensor receiving device mounted on a flying platform in the air above the measuring area.

[0128] Based on the rotational invariance of the horizontal total magnetic field, the inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tending to 0. The inversion target quantity of the survey area is obtained by iteratively solving the inversion objective function. Among them, the horizontal total magnetic field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal total magnetic field response quantity of the observation point.

[0129] For the specific implementation process of each step, please refer to the description of the embodiment of the ground-to-air wide-area electromagnetic method response extraction method based on the horizontal total magnetic field.

[0130] In some embodiments, as Figure 9 As shown, the electronic components of the electronic terminal include:

[0131] Processor 1600 may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor. Processor 1600 is configured to execute relevant programs to implement the technical solutions provided by the embodiments of the present invention.

[0132] Memory 1700 can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). Memory 1700 can store an operating system and other application programs. When implementing the technical solutions provided in the embodiments of this specification through software or firmware, the relevant program code is stored in memory 1700 and is called by processor 1600 to execute the algorithm program of the method for extracting the ground-to-air wide-area electromagnetic response based on the horizontal total magnetic field according to the embodiment of the present invention.

[0133] The input / output interface 1800 is used to implement information input and output.

[0134] The communication interface 1900 is used to realize communication interaction between this device and other devices. Communication can be achieved through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0135] The bus 2000 transmits information between various components of the device (eg, the processor 1600 , the memory 1700 , the input / output interface 1800 , and the communication interface 1900 ).

[0136] The processor 1600 , the memory 1700 , the input / output interface 1800 , and the communication interface 1900 are connected to each other in communication within the device via the bus 2000 .

[0137] In some embodiments, the technical solution of the present invention further provides a computer-readable storage medium storing a computer program, which is called by a processor to implement:

[0138] Collect / acquire two-component horizontal magnetic field data of aerial measurement points as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal total magnetic field observation quantity. The two-component horizontal magnetic field data of aerial measurement points are obtained by using a ground-based transmitting source set up outside the measurement area and a magnetic field sensor receiving device mounted on a flying platform in the air above the measurement area;

[0139] Based on the rotational invariance of the horizontal total magnetic field, the inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tending to 0. The inversion target quantity of the survey area is obtained by iteratively solving the inversion objective function. Among them, the horizontal total magnetic field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal total magnetic field response quantity of the observation point.

[0140] For the specific implementation process of each step, please refer to the description of the embodiment of the ground-to-air wide-area electromagnetic method response extraction method based on the horizontal total magnetic field.

[0141] The readable storage medium is a computer-readable storage medium, which can be an internal storage unit of the software and hardware device described in any of the aforementioned embodiments, such as a hard disk or memory of a controller. The readable storage medium can also be an external storage device of the controller, such as a plug-in hard disk equipped on the controller, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. Furthermore, the readable storage medium can also include both an internal storage unit of the controller and an external storage device. 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 is to be output.

[0142] Based on this understanding, the technical solution of the present invention, or the portion 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 instructions for causing a computer device (such as a personal computer, server, or network device) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned readable storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0143] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can adopt the form of a computer program product implemented 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. The present application is a flow chart according to the method, device (system), and computer program product of the embodiment of the present application and / or the instructions executed by the processor to generate a device for realizing the function specified in one flow chart or multiple flows and / or one box or multiple boxes of the block diagram. These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a product comprising an instruction device, which realizes the function specified in one flow chart or multiple flows and / or one box or multiple boxes of the block diagram. These computer program instructions may also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0144] It should be emphasized that the examples described in the present invention are illustrative rather than restrictive. Therefore, the present 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 solution of the present invention that do not depart from the purpose and scope of the present invention, whether modified or replaced, also fall within the scope of protection of the present invention.

Claims

1. A method for extracting ground-to-air wide-area electromagnetic responses based on the horizontal total magnetic field, characterized by: The following steps are involved: S1. Set up a ground transmitting source outside the measurement area, and use a flying platform to carry a magnetic field sensor receiving device in the air above the measurement area to collect / acquire two-component horizontal magnetic field data as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal magnetic field observation quantity; S2. Based on the rotational invariance of the horizontal total magnetic field, an inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation approaching 0, and the inversion objective function is iteratively solved to obtain the inversion target quantity of the survey area; The horizontal magnetic total field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal magnetic total field response of the observation point.

2. The method for extracting ground-air wide-area electromagnetic responses according to claim 1, characterized in that: The rotation invariance of the horizontal total magnetic field is: when the magnetic field sensor shakes in the horizontal direction and the rotation angle of the magnetic field sensor changes, the single component value of the horizontal magnetic field will change, but the horizontal total magnetic field remains unchanged.

3. The method for extracting ground-air wide-area electromagnetic responses according to claim 1, characterized in that: The inversion objective function is expressed as: ； Where, is the inversion objective function value, and Perform iterative solution, is the total horizontal magnetic field response, is the total horizontal magnetic field observation quantity, is the inversion target quantity.

4. The method for extracting ground-air wide-area electromagnetic responses according to claim 3, characterized in that: Use dichotomy to Perform iterative solution, the specific process is: For inversion target quantity Set the value range And set the iteration termination condition; calculate Is it less than 0? If it is less than 0, take and calculate Otherwise, adjust the value range ; according to Less than 0 or Less than 0, corresponding to a narrowed value range for or ; Determine whether the iteration termination condition is met. If so, obtain the inversion target quantity based on the current value interval; otherwise, continue to take the median value to narrow the value interval and proceed to the next round of iteration.

5. The method for extracting ground-air wide-area electromagnetic responses according to claim 1, characterized in that: The theoretical equation of the total horizontal magnetic field response is: = , is the total horizontal magnetic field response, 、 are the horizontal magnetic field components in the x and y directions respectively, is the inversion target quantity; Among them, in layered media, the expression of the horizontal magnetic field component value received by the aerial observation point after the ground transmission source transmits is: ； ； Under the uniform half-space model, the expression of the horizontal magnetic field component value received by the aerial observation point after the ground transmission source is transmitted is: ； ； Where I is the magnitude of the current injected into the ground by the source outside the measurement area, ds is the length of the dipole, r is the transmitting and receiving distance, that is, the distance between the ground source and the observation point projected onto the geodetic coordinate system, x, y, and z are the coordinates of the observation point, the z direction is vertically downward, the coordinates of the electric dipole are (0, 0, -h), and h is the height from the ground; is the integral term of the Bessel function, and are zero-order and first-order Bessel functions, respectively, with parameters ,parameter , is the magnetic permeability in vacuum, is the circular frequency, and are the resistivities in the air layer and the first underground medium, respectively; is the reflection coefficient of the TM mode, is the reflection coefficient of the TE mode.

6. The method for extracting ground-air wide-area electromagnetic responses according to claim 1, characterized in that: The inversion target quantity is resistivity.

7. A device based on the method for extracting ground-to-air wide-area electromagnetic responses according to any one of claims 1 to 6, characterized in that: The device comprises at least a ground transmitting source arranged outside the measurement area, a flying platform arranged in the air above the measurement area, and a magnetic field sensor receiving device carried on the flying platform; The ground transmitting source is excited by a grounded galvanic source to transmit electromagnetic waves of different frequencies; The magnetic field sensor receiving device receives magnetic field data and transmits it to the built-in controller or the external controller connected by communication so that the controller calculates the inversion target quantity according to the magnetic field data in the manner of step S2.

8. A system based on the method for extracting ground-to-air wide-area electromagnetic responses according to any one of claims 1 to 6, characterized in that: include: The magnetic field data acquisition module is used to collect / acquire the two-component horizontal magnetic field data of the aerial measurement point as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal magnetic field total field observation quantity; The processing module is used to construct an inversion objective function based on the rotation invariance of the horizontal total magnetic field and the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tends to 0, and iteratively solve the inversion objective function to obtain the inversion target quantity of the survey area; The horizontal magnetic total field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal magnetic total field response of the observation point.

9. An electronic device, characterized in that: include: one or more processors; and a memory storing one or more computer programs; The processor calls a computer program to implement: Collect / acquire two-component horizontal magnetic field data of the aerial measuring point as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal magnetic field observation quantity. The two-component horizontal magnetic field data of the aerial measuring point is obtained by using a ground-based transmitting source set up outside the measurement area and a magnetic field sensor receiving device mounted on a flying platform in the air above the measurement area; Based on the rotation invariance of the horizontal total magnetic field, the inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tending to 0. The inversion target quantity of the survey area is obtained by iteratively solving the inversion objective function. The horizontal magnetic total field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal magnetic total field response of the observation point.

10. A computer-readable storage medium, characterized in that: A computer program is stored, which is called by a processor to implement: Collect / acquire two-component horizontal magnetic field data of the aerial measuring point as the horizontal magnetic field observation quantity of the observation point, which is used to calculate the horizontal magnetic field observation quantity. The two-component horizontal magnetic field data of the aerial measuring point is obtained by using a ground-based transmitting source set up outside the measurement area and a magnetic field sensor receiving device mounted on a flying platform in the air above the measurement area; Based on the rotation invariance of the horizontal total magnetic field, the inversion objective function is constructed with the difference between the horizontal total magnetic field response and the horizontal total magnetic field observation tending to 0. The inversion target quantity of the survey area is obtained by iteratively solving the inversion objective function. The horizontal magnetic total field response is calculated by substituting the set inversion target quantity into the theoretical equation of the horizontal magnetic total field response of the observation point.

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