Transient electromagnetic three-dimensional positioning method for electrically abnormal body

Abstract

The invention relates to the technical field of electromagnetic detection, in particular to an electrically anomalous body transient electromagnetic three-dimensional positioning method, which comprises the following steps: acquiring transient electromagnetic three-component response data of each measuring point according to detection requirements; carrying out matrix transformation on the data of all the measuring points by adopting the constructed transformation matrix to obtain transformed transient electromagnetic response data; calculating a pointing vector of each measuring point in each time channel based on the converted transient electromagnetic response data; calculating a positioning line segment of each measuring point in each time channel based on the coordinate of each measuring point and the corresponding pointing vector; and selecting a certain time channel, drawing positioning line segments of all measuring points, and picking up intersection points of the positioning line segments to determine the spatial position of the electrically abnormal body. According to the method, the transient electromagnetic three-component response data is subjected to transformation processing, the positioning line segment is directly calculated, the three-dimensional space position of the electrically abnormal body can be determined without depending on iterative inversion, the positioning precision and the uniqueness of the positioning result are effectively improved, and the calculation efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic detection technology, specifically to a transient electromagnetic three-dimensional positioning method for electrical anomalies. Background Technology

[0002] The Transient Electromagnetic Method (TEM) is a geophysical exploration method based on the principle of electromagnetic induction. Its basic operation involves transmitting a pulsed magnetic field into the subsurface via transmitting coils. After the primary field is suddenly cut off, the secondary attenuated field caused by eddy currents induced in the subsurface medium is measured. By analyzing the variation of the secondary attenuated field over time, the electrical distribution structure of the subsurface medium can be inferred. The TEM is characterized by its large detection depth, high resolution, and sensitivity to low-resistivity bodies, and is widely used in mineral resource exploration, groundwater detection, engineering geological surveys, and environmental geophysics.

[0003] In transient electromagnetic detection, the accurate location of electrical anomalies is a key technology. Currently, commonly used location methods are mainly divided into two categories: one is the direct location method based on transient electromagnetic response characteristics or apparent resistivity parameters, and the other is the model fitting location method based on inversion calculation.

[0004] The first type of method typically infers information based on the amplitude, time constant, or abnormal morphology in the apparent resistivity section of the anomalous response. Although this type of method is computationally simple, its results are relatively coarse, its spatial resolution is limited, and it is difficult to achieve precise three-dimensional positioning.

[0005] The second type of method constructs a geoelectric model and repeatedly performs forward modeling calculations to fit the observed data, thereby inferring the distribution of electrical parameters of the subsurface medium. Theoretically, this method can achieve higher positioning accuracy, but in practical applications, it is limited by the nonlinearity and multiple solutions of the inversion problem. This often leads to insufficient convergence stability, heavy reliance on the initial model selection for calculation results, and low computational efficiency. Especially in multi-parameter collaborative inversion, the calculation process is prone to getting trapped in local extrema, thus affecting the reliability and spatial resolution of the positioning results. Summary of the Invention

[0006] In view of this, the present invention provides a transient electromagnetic three-dimensional positioning method for electrical anomalies, which aims to solve the problems of insufficient accuracy in three-dimensional positioning of underground electrical anomalies, strong multiple solutions in inversion interpretation, and low computational efficiency in existing transient electromagnetic detection technologies, thereby improving the accuracy, uniqueness, and computational efficiency of determining the spatial location of electrical anomalies.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for transient electromagnetic three-dimensional localization of an electrically anomalous bodies, comprising the following steps: S1. Based on the detection requirements, conduct transient electromagnetic measurements to obtain transient electromagnetic three-component response data at each measuring point; S2. The transient electromagnetic three-component response data is processed by a constructed transformation matrix. T The transformation process is performed to obtain the transformed transient electromagnetic response data; S3. Based on the transformed transient electromagnetic response data, calculate the pointing vector of each measuring point in each time channel. C ij ; S4. Based on the coordinates of each measuring point and its corresponding pointing vector C ij Calculate the positioning line segment of each measuring point in each time channel; S5. Select a certain time channel, draw the positioning line segments of all measuring points, and pick the intersection of the positioning line segments to determine the spatial location of the electrical anomaly.

[0008] In one specific implementation scheme, in step S1, the acquired transient electromagnetic three-component response data is stored as a dataset. L : L =[ D 1, D 2, ..., D i , ..., D m ]; in, L This is a collection of transient electromagnetic data from different measurement points. i The measurement point is numbered, and its corresponding coordinates are... P i = [ x i , y i , z i ]; D i For the first i Transient electromagnetic three-component response data at each measurement point; m This represents the number of measurement points.

[0009] In a specific feasible implementation, transient electromagnetic three-component response data D i 3 lines n Column matrix: ; n The number of time channels for each measurement point. dxij For the corresponding number i The first measuring point j Time Channel t j of x Component transient electromagnetic response value, d yij For the corresponding number i The first measuring point j Time Channel t j of y Component transient electromagnetic response value, d zij For the corresponding number i The first measuring point j Time Channel t j of z Component transient electromagnetic response value.

[0010] In one specific implementation, in step S2, the constructed transformation matrix T order n The length of the transient electromagnetic response time series, i.e., the number of time channels, is equal to the transformation matrix constructed therefrom. T Perform matrix transformation on the transient electromagnetic three-component response data of each measuring point; Wherein, the constructed transformation matrix T The sum of the values ​​in each row is 1, and each row is smoothed using one point before and one point after it; for the first row, T (1,1)=2 / 3, T (1,2) = 1 / 3, and the remaining elements in the first row are 0; for the last row... T ( n , n -1) = 1 / 3, T ( n , n = 2 / 3, and the remaining elements in the last row are 0. n For time-related numbers.

[0011] In one specific implementation, in step S2, the constructed transformation matrix is ​​used. T Transient electromagnetic response data at all measuring points D i Perform matrix transformation to obtain the transformed transient electromagnetic response data. D i}={ D i × T}

[0012] In one specific implementation, in step S3, the pointing vector Cij The calculation formula is: ; in, , b This is the distance coefficient.

[0013] In one specific implementation scheme, in step S4, for the first... j The time path is calculated separately for the first time stage. i The positioning line segment of each measuring point, the starting point of the line segment End point of line segment ; For the first i The coordinates of the measuring points C ij For the first i The measuring point at the ... j The pointing vector of each time channel.

[0014] In one specific feasible implementation, the distance coefficient b The value is determined through human-computer interaction, and the principle for determination is to ensure that the positioning line segments can intersect.

[0015] In one specific implementation, the human-computer interaction method is to use a pointing device to click on the intersection of the positioning line segments.

[0016] Compared with existing technologies, the transient electromagnetic three-dimensional positioning method for electrical anomalies described in this invention is used for spatial positioning of underground electrical anomalies. By systematically acquiring and transforming transient electromagnetic three-component response data, it extracts response features that sensitively reflect the spatial location of the anomaly. Combining this with the transformed transient electromagnetic response data, it directly calculates the positioning line segment, achieving direct determination of the three-dimensional spatial location of the electrical anomaly without relying on iterative inversion. This effectively improves the positioning accuracy, result reliability, and computational efficiency of transient electromagnetic detection, and has the following beneficial effects: 1. Compared with traditional methods for anomaly delineation based on transient electromagnetic field values ​​or apparent resistivity parameters, this invention can extract the spatial response characteristics of anomalies more accurately by transforming the transient electromagnetic three-component response data, thereby improving the three-dimensional positioning accuracy of electrical anomalies.

[0017] 2. Compared with methods that rely on inversion algorithms to infer the location of anomalies, this invention achieves localization through direct calculation and feature extraction, avoiding problems such as convergence instability and reliance on the initial model caused by nonlinearity and multiple solutions during the inversion process, thus enhancing the uniqueness and reliability of the localization results.

[0018] 3. This invention directly obtains the location of the anomaly by constructing a clear transformation matrix and pointing vector calculation formula, without the need for complex iterative inversion calculations, which greatly improves the calculation efficiency and has good practicality while ensuring high positioning accuracy. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of transient electromagnetic detection of a sphere in a uniform earth.

[0021] Figure 2 This is the transient electromagnetic three-component response data for the 11th time trace in a uniform earth.

[0022] Figure 3 This is the transformed transient electromagnetic three-component response data of the 11th time trace in a uniform ground.

[0023] Figure 4 The location results of the electrical anomaly in the 11th time trace of a uniform earth are compared with the actual model.

[0024] Figure 5 This is a schematic diagram of transient electromagnetic detection of a sphere within two layers of the earth.

[0025] Figure 6 Distance coefficient between two geodetic layers b The positioning result when the value is 5.

[0026] Figure 7 Distance coefficient between two geodetic layers b The positioning result when the value is 50.

[0027] Figure 8 Distance coefficient between two geodetic layers b The location result when the value is 500.

[0028] Figure 9 This is an overall flowchart of the transient electromagnetic three-dimensional localization method for an electrical anomaly body according to the present invention. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] The present invention discloses a transient electromagnetic three-dimensional positioning method for electrical anomalies. By systematically collecting and transforming transient electromagnetic three-component response data, the method extracts response features that can sensitively reflect the spatial location of the anomaly, and then directly calculates the three-dimensional spatial location of the anomaly. This method does not rely on a complex and ambiguous inversion calculation process, effectively improving the positioning accuracy and reliability of transient electromagnetic anomalies, suppressing ambiguity, and ultimately achieving unique and accurate three-dimensional positioning of underground electrical anomalies.

[0031] This invention directly calculates the location of the anomaly based on transient electromagnetic response data using formulas. The location result depends entirely on the transient electromagnetic response data and is unique.

[0032] The technical concept of this invention stems from the fact that transient electromagnetic three-component response data contains the spatial location information of anomalies. The spatial location of the anomaly is directly extracted using a formula, offering advantages over traditional inversion methods, including unique results, no need for iteration, and rapid calculation. In contrast, this method only locates the anomaly without acquiring information such as its range or conductivity value.

[0033] like Figure 9 As shown, the transient electromagnetic three-dimensional localization method for an electrically anomalous body according to the present invention includes the following steps: S1. Based on the detection requirements, conduct transient electromagnetic measurements to obtain transient electromagnetic three-component response data at each measuring point; Transient electromagnetic measurements typically employ a ground-based transmission line. A transmitter sends a stable constant-current square wave into the transmission line. Immediately after the square wave current is switched off, the receiver begins operation, acquiring a series of transient electromagnetic three-component response data over a time channel, i.e., a matrix. D ; For example, the acquired transient electromagnetic three-component response data is stored as a transient electromagnetic response dataset. L : L =[ D 1, D 2, ..., D i , ..., D m ]; in, L This is a collection of transient electromagnetic data from different measurement points. iThe measurement point is numbered, and its corresponding coordinates are... P i = [ x i , y i , z i ]; D i For the first i Transient electromagnetic three-component response data at each measurement point; m The number of measuring points; ; in, n The number of time channels for each measurement point. d xij For the corresponding number i The first measuring point j Time Channel t j of x Component transient electromagnetic response value, d yij For the corresponding number i The first measuring point j Time Channel t j of y Component transient electromagnetic response value, d zij For the corresponding number i The first measuring point j Time Channel t j of z Component transient electromagnetic response value; S2, for the first i Transient electromagnetic three-component response data at each measuring point D i The constructed transformation matrix T for n OK n List: ; Transformation matrix T The construction rule is: its order n Equal to the length of the transient electromagnetic response time series, i.e., the number of time channels; through the constructed transformation matrix T To smooth the transient electromagnetic response data while maintaining its original magnitude, the sum of the values ​​in each row is 1. Smoothing is performed using one point before and one point after the current row, for a total of three points. Therefore, the weight of each point is... For the first line ( i =1), T (1,1) = 2 / 3, T(1,2) = 1 / 3, the remaining elements in the first row are 0; for the last row ( i = n ), T ( n , n -1) = 1 / 3, T ( n , n = 2 / 3, and the remaining elements in the last row are 0; Transformation matrix constructed T Transient electromagnetic response data at all measuring points D i Perform matrix transformation to obtain the transformed transient electromagnetic response data. D i}={ D i × T}; Constructing the transformation matrix T The purpose is to smooth the transient electromagnetic response data, making subsequent positioning calculations more stable and facilitating intersection point picking. S3, for the first i The first measuring point j Based on the transient electromagnetic response law, the direction of the electrical anomaly that produces this response can be calculated from the three-component transient electromagnetic response data. Specifically, the pointing vector at each measurement point can be calculated using the transformed transient electromagnetic response data. C ij The pointing vector C ij The direction from the observation point to the electrical anomaly represents the direction of the anomaly relative to the observation point. It contains three elements and is physically a spatial direction vector, which has no inherent dimension and is a pointing vector. C ij The calculation formula is: ; in, , b This is a distance coefficient used to control the length of the positioning line segments. Its value needs to be determined through human-computer interaction. The principle for determining this value is to ensure that the positioning line segments can intersect without being too long to affect pickup; it is generally set between 10 and 200. It should be noted that the distance coefficient... b This is only to ensure that the intersection point will not change due to different lengths selected by different people, and therefore will not affect the positioning result; S4, regarding the first j The time path is calculated separately for the first time stage. i The positioning line segment of each measuring point, the starting point of the line segment End point of line segment ; S5. For a given time channel, draw the positioning line segments for all measurement points. By observation, and using a human-computer interaction method (e.g., using a pointing device such as a mouse or touchscreen to click), pick the intersection points of the positioning line segments. This is the positioning result of the electrical anomaly. Following the above steps, the positioning results of electrical anomalies representing different locations in other time channels can be obtained.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1 S1. A conductive sphere exists in uniform ground with a resistivity of 500 Ω•m. The sphere has a radius of 50 m and a resistivity of 10 Ω•m, is buried at a depth of 150 m, and its center is located at (50, 50, 150) m. To detect this sphere, a transmission loop with sides of 200 m × 200 m is used, with its center located at (0, 0, 0) m. The main survey line is located at... x =0m、 z On the straight line where =0m, x The coordinate range is -200m to 260m, the point spacing is 20m, and the point numbers correspond to 0, 20, 40, ..., 460. The geometric relationship is as follows: Figure 1 As shown.

[0036] Conduct transient electromagnetic measurements to obtain transient electromagnetic three-component response data: L =[ D 1, D 2, ..., D i , ..., D m ]; ; in, L This is a collection of transient electromagnetic response data from different measuring points. D i For the first i Transient electromagnetic three-component response data at each measuring point, corresponding to the coordinates are: P i = [ x i , y i , z i ], i Number the measurement points. m For the number of measurement points, m =24, n The number of time channels for each measurement point, n =31, d xijFor the corresponding number i The first measuring point j Time Channel t j of x Component transient electromagnetic response value, d yij For the corresponding number i The first measuring point j Time Channel t j of y Component transient electromagnetic response value, d zij For the corresponding number i The first measuring point j Time Channel t j of z The transient electromagnetic response values, where the transient electromagnetic three-component response data for the 11th time channel are as follows: Figure 2 As shown; S2, for the first i Transient electromagnetic three-component response data at each measuring point D i ,structure n OK n Transformation matrix of columns T : use T Transient electromagnetic response data at all measuring points D i Perform matrix transformation to obtain the transformed transient electromagnetic response data. D i}={ D i × T The transient electromagnetic response data after transformation in the 11th time channel is as follows: Figure 3 As shown; S3, for the first i The first measuring point j Each time channel is used to calculate the pointing vector at the measurement point using the transformed transient electromagnetic response data. The calculation formula is: ; in, , b The distance coefficient is selected through human-computer interaction in this embodiment. b =50; S4, regarding the first j The time path is calculated separately for the first time stage. i The positioning line segment of each measuring point, the starting point of the line segment End point of line segment ; S5. For the 11th time channel, draw the positioning line segments for all measurement points and pick the intersection points of the positioning line segments. This is the positioning result of the electrical anomaly. Figure 4 As shown.

[0037] Example 2 The present invention will now be described in further detail with reference to a second specific embodiment.

[0038] S1. A conductive sphere exists between two layers of earth. The resistivity of the first layer is 1000 Ω•m, and its thickness is 100 m. The resistivity of the second layer is 500 Ω•m. The sphere has a radius of 50 m, a resistivity of 10 Ω•m, and is buried at a depth of 200 m. Its center is located at (50, 70, 200) m. To detect this sphere, a 300 m × 300 m transmission loop is used, with its center located at (0, 0, 0) m. The main survey line is located at... x =0m、 z On the straight line where =0m, x The coordinate range is -200m to 260m, the point spacing is 20m, and the point numbers correspond to 0, 20, 40, ..., 460. The geometric relationship is as follows: Figure 5 As shown.

[0039] Conduct transient electromagnetic measurements to obtain a dataset of transient electromagnetic three-component responses: L =[ D 1, D 2, ..., D i , ..., D m ]; ; in, L This is a collection of transient electromagnetic response data from different measuring points. D i For the first i Transient electromagnetic three-component response data at each measuring point, corresponding to the coordinates are: P i = [ x i , y i , z i ], i Number the measurement points. m For the number of measurement points, m =24, n The number of time channels for each measurement point, n =31, d xij For the corresponding number iThe first measuring point j Time Channel t j of x Component transient electromagnetic response value, d yij For the corresponding number i The first measuring point j Time Channel t j of y Component transient electromagnetic response value, d zij For the corresponding number i The first measuring point j Time Channel t j of z The transient electromagnetic response values ​​of the components are used to locate the ore body by selecting the transient electromagnetic three-component response data of the 11th time channel. S2, for the first i Transient electromagnetic three-component response data at each measuring point D i ,structure n OK n Transformation matrix of columns T : use T Transient electromagnetic response data at all measuring points D i Perform matrix transformation to obtain the transformed transient electromagnetic response data. D i}={ D i × T}; S3, for the first i The first measuring point j Each time channel is used to calculate the pointing vector at the measurement point using the transformed transient electromagnetic response data. The calculation formula is: ; in, , b The distance coefficient is selected through human-computer interaction in this embodiment. b =50; S4, regarding the first j The time path is calculated separately for the first time stage. i The positioning line segment of each measuring point, the starting point of the line segment End point of line segment ; S5. For the 11th time channel, draw the positioning line segments of all measurement points and pick the intersection of the positioning line segments, which is the positioning result of the electrical anomaly. Figure 6 , Figure 7 , Figure 8 Distance coefficients were displayed respectively. b The positioning results are shown when the distance coefficient is 5, 50, and 500. As can be seen from the figure, when the distance coefficient... b When the value is 5, the positioning line segment is too short to intersect at a single point, making it impossible to pick up; when the distance coefficient is 5... b When the value is 500, the positioning line segment is too long, making it inconvenient to observe and pick up; while when the distance coefficient is... b When the value is 50, the length of the positioning line segment is appropriate, which is beneficial for position picking.

[0040] The results of the electrical anomaly localization show that the location of the anomaly center in this invention is close to the actual value, indicating that the localization method of this invention can effectively obtain the anomaly center location parameters.

[0041] As can be seen from the above embodiments, the direction of the positioning line segment is uniquely determined by the transient electromagnetic three-component response, and the positioning result is uniquely determined by the intersection of the positioning line segments. This positioning method does not rely on numerical fitting, does not rely on initial values, and has no mathematical basis for generating multiple solutions, thus avoiding "multiple solutions" in terms of mechanism.

[0042] The various embodiments described in this specification are presented in a progressive manner, and similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A transient electromagnetic three-dimensional localization method for an electrically anomalous body, characterized in that, Includes the following steps: S1. Based on the detection requirements, conduct transient electromagnetic measurements to obtain transient electromagnetic three-component response data at each measuring point; S2. The transient electromagnetic three-component response data is processed by a constructed transformation matrix. T The transformation process is performed to obtain the transformed transient electromagnetic response data; S3. Based on the transformed transient electromagnetic response data, calculate the pointing vector of each measuring point in each time channel. C ij ; S4. Based on the coordinates of each measuring point and its corresponding pointing vector C ij Calculate the positioning line segment of each measuring point in each time channel; S5. Select a certain time channel, draw the positioning line segments of all measuring points, and pick the intersection of the positioning line segments to determine the spatial location of the electrical anomaly.

2. The transient electromagnetic three-dimensional localization method for an electrically anomalous body according to claim 1, characterized in that, In step S1, the acquired transient electromagnetic three-component response data is stored as a dataset. L : L =[ D 1， D 2，…， D i ，…， D m ]； in, L This is a collection of transient electromagnetic data from different measurement points. i The measurement point is numbered, and its corresponding coordinates are... P i = [ x i , y i , z i ]; D i For the first i Transient electromagnetic three-component response data at each measurement point; m This represents the number of measurement points.

3. The transient electromagnetic three-dimensional localization method for an electrically anomalous body according to claim 2, characterized in that, Transient electromagnetic three-component response data D i 3 lines n Column matrix: ； n The number of time channels for each measurement point. d xij For the corresponding number i The first measuring point j Time Channel t j of x Component transient electromagnetic response value, d yij For the corresponding number i The first measuring point j Time Channel t j of y Component transient electromagnetic response value, d zij For the corresponding number i The first measuring point j Time Channel t j of z Component transient electromagnetic response value.

4. The transient electromagnetic three-dimensional localization method for an electrically anomalous body according to claim 3, characterized in that, In step S2, the constructed transformation matrix T order n The length of the transient electromagnetic response time series, i.e., the number of time channels, is equal to the transformation matrix constructed therefrom. T Perform matrix transformation on the transient electromagnetic three-component response data of each measuring point; Wherein, the constructed transformation matrix T The sum of the values ​​in each row is 1, and each row is smoothed using one point before and one point after it; for the first row, T (1,1)=2 / 3, T (1,2) = 1 / 3, and the remaining elements in the first row are 0; for the last row... T ( n , n -1) = 1 / 3, T ( n , n = 2 / 3, and the remaining elements in the last row are 0. n For time-based number of channels.

5. The transient electromagnetic three-dimensional localization method for an electrically anomalous body according to claim 4, characterized in that, In step S2, the constructed transformation matrix is ​​used. T Transient electromagnetic response data at all measuring points D i Perform matrix transformation to obtain the transformed transient electromagnetic response data. D i }={ D i × T } 6. The transient electromagnetic three-dimensional localization method for an electrically anomalous body according to claim 3, characterized in that, In step S3, the pointing vector C ij The calculation formula is: ； in, , b This is the distance coefficient.

7. The transient electromagnetic three-dimensional localization method for an electrically anomalous body according to claim 6, characterized in that, In step S4, for the first j The time path is calculated separately for the first time stage. i The positioning line segment of each measuring point, the starting point of the line segment End point of line segment ; For the first i The coordinates of the measuring points C ij For the first i The measuring point at the ... j The pointing vector of each time channel.

8. The transient electromagnetic three-dimensional localization method for an electrically anomalous body according to claim 6, characterized in that, The distance coefficient b The value is determined through human-computer interaction, and the principle for determination is to ensure that the positioning line segments can intersect.

9. The transient electromagnetic three-dimensional localization method for an electrically anomalous body according to claim 8, characterized in that, The human-computer interaction method involves using a pointing device to click and pick up the intersection of the positioning line segments.

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