Deep prospecting method and system based on ground-air electromagnetic detection

Abstract

The invention discloses a deep prospecting method and system based on ground-air electromagnetic detection, and relates to the technical field of geological mineral exploration. The method comprises the following specific steps: obtaining geological background data of a research area, carrying out field survey, determining transmitting and receiving positions, and carrying out ground-air transient electromagnetic measurement at different flight height positions to obtain ground-air electromagnetic detection data; preprocessing the ground-air electromagnetic detection data to obtain preprocessed data; performing inversion on the preprocessed data by using an inversion algorithm to obtain an electrical structure model of the underground medium; and according to the electrical structure model, predicting distribution and characteristics of an underground geologic body, and determining a mineral product position. According to the method, ground-air transient electromagnetic measurement is adopted for deep prospecting, denoising operation is carried out on the obtained data, and the exploration precision of deep mineral resources in the complex terrain area is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of geological mineral exploration, and in particular to a deep mineral prospecting method and system based on ground-to-air electromagnetic detection. Background Art

[0002] Mineral resources occupy an important position in natural resources. They are the material resource basis for human survival and an important resource for ensuring national security and economic development. The prospecting method for deep ore bodies is completely different from that for shallow ore bodies. Traditional prospecting methods require comprehensive analysis of geological and geochemical data to infer the burial depth and occurrence state of the ore body. However, the prospecting information of deep ore bodies is different from that of shallow ore bodies. It has obvious discontinuity in time and space. It is difficult for traditional prospecting methods to directly obtain deep ore body information. In recent years, with the improvement of research and understanding, deep prospecting has gradually attracted attention at home and abroad. However, due to the increasing depletion of shallow mineral resources, people pay more and more attention to deep prospecting. Therefore, it is urgent to carry out deep prospecting based on shallow prospecting methods. Summary of the invention

[0003] The purpose of the present invention is to provide a deep prospecting method and system based on ground-to-air electromagnetic detection to solve the problems raised in the background technology.

[0004] To achieve the above object, the present invention provides the following solutions: On the one hand, a deep prospecting method based on ground-to-air electromagnetic detection is provided, and the specific steps include the following:

[0005] Obtain geological background information of the study area and conduct field surveys to determine the transmitting and receiving locations, conduct ground-to-air transient electromagnetic measurements at different flight altitudes, and obtain ground-to-air electromagnetic detection data;

[0006] Preprocessing the ground-to-air electromagnetic detection data to obtain preprocessed data;

[0007] Inverting the preprocessed data using an inversion algorithm to obtain an electrical structure model of the underground medium;

[0008] Based on the electrical structure model, the distribution and characteristics of underground geological bodies can be predicted and the location of minerals can be determined.

[0009] Preferably, preprocessing the ground-to-air electromagnetic detection data includes cleaning, denoising, baseline correction, and off-time removal.

[0010] Preferably, the specific steps of denoising the ground-to-air electromagnetic detection data are:

[0011] Segmenting the ground-to-air electromagnetic detection data to obtain single-point ground-to-air electromagnetic measurement data;

[0012] Preprocessing the ground-to-air electromagnetic measurement data using a weighted mean filtering method to extract attenuation characteristics of the ground-to-air electromagnetic data;

[0013] Establishing an exponential fitting prediction equation according to the attenuation characteristics, performing an exponential fitting on the ground-to-air electromagnetic measurement data, and obtaining a fitting output result;

[0014] An adaptive scalar Kalman filter is established, and the fitting output result is input into the filter as a prediction value to filter out electromagnetic noise and extract effective signals.

[0015] Preferably, the baseline correction is performed using a Savitzky-Golay smoothing filter method.

[0016] Preferably, multiple survey lines are arranged in the overlying strata of the ore body according to the stratum, structure, lithology and physical property characteristics. The principle of survey line arrangement is: one survey line has no less than two measuring points, and the distance between two adjacent survey lines is 200m, among which the ground electromagnetic measuring points are arranged above the ore body, and the airborne ground-to-air electromagnetic measuring points are arranged between the ground and airborne electromagnetic measuring points.

[0017] Preferably, the specific steps of inverting the preprocessed data using the inversion algorithm are:

[0018] Firstly, the underground space in the inversion area is divided into rectangular grids, the center coordinates and corresponding side lengths of each grid unit are determined, and the distance parameters of each grid unit are determined;

[0019] The ground data kernel matrix and the aerial data kernel matrix corresponding to different measurement heights are calculated according to the total magnetization direction, geomagnetic direction and the center coordinates and corresponding side lengths of each grid cell in the inversion area, and the pre-optimization factor corresponding to each grid cell is calculated according to the corresponding distance parameter to generate the pre-optimization matrix;

[0020] The ground data kernel matrix and the aerial data kernel matrix are combined into a total kernel matrix, and all observation data are combined into a total observation data matrix;

[0021] Establishing a joint inversion objective equation based on the pre-optimized matrix, the total observation data matrix, and the total kernel matrix;

[0022] The pre-optimized conjugate gradient algorithm is used to solve the joint inversion target equation to obtain the electrical structure model of the underground medium.

[0023] Preferably, the geological background data of the study area include metallogenic geological processes, metallogenic structural systems, metallogenic geological characteristics, and prospecting marker information.

[0024] Preferably, it also includes arranging drill holes for deep verification of the determined mineral locations to complete the deep prospecting process.

[0025] On the other hand, a deep prospecting system based on ground-to-air electromagnetic detection is provided, including a data acquisition module, a preprocessing module, an inversion module, and a prediction module; wherein:

[0026] The data acquisition module is used to obtain geological background information of the research area and conduct field surveys, determine the transmitting and receiving positions, carry out ground-to-air transient electromagnetic measurements at different flight altitudes, and obtain ground-to-air electromagnetic detection data;

[0027] The preprocessing module is used to preprocess the ground-to-air electromagnetic detection data to obtain preprocessed data;

[0028] The inversion module is used to invert the preprocessed data using an inversion algorithm to obtain an electrical structure model of the underground medium;

[0029] The prediction module is used to predict the distribution and characteristics of underground geological bodies and determine the location of mineral resources based on the electrical structure model.

[0030] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0031] 1. The ground-to-air transient electromagnetic measurement method is used to quickly obtain transient electromagnetic response data at different flight altitudes in the air to reconstruct the multi-parameter earth model, weaken the singularity problem of multi-parameter reconstruction, solve the multi-solution problem of inversion and reconstruction results, and improve the accuracy of transient electromagnetic multi-parameter detection.

[0032] 2. The detection depth of the ground-to-air electromagnetic detection system has been increased, which has important application value in the field of rapid detection at great depths in complex terrain areas, and helps in the exploration of deep mineral resources in complex terrain areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 creative labor.

[0034] Figure 1 is a flow chart of the method of the present invention;

[0035] Figure 2 It is a system structure diagram of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] The purpose of the present invention is to provide a deep prospecting method based on ground-to-air electromagnetic detection, such as Figure 1 The specific steps include:

[0038] S1. Obtain geological background information of the study area and conduct field surveys to determine the transmitting and receiving positions, conduct ground-to-air transient electromagnetic measurements at different flight altitudes, and obtain ground-to-air electromagnetic detection data;

[0039] S2, preprocessing the ground-to-air electromagnetic detection data to obtain preprocessed data;

[0040] S3, using an inversion algorithm to invert the preprocessed data to obtain an electrical structure model of the underground medium;

[0041] S4. Based on the electrical structure model, predict the distribution and characteristics of underground geological bodies and determine the location of minerals.

[0042] It should be noted that the ground-to-air transient electromagnetic method (TEM) is a geophysical exploration technology used for deep mineral exploration, which has significant advantages and application potential. This method combines the advantages of aviation and ground transient electromagnetic methods, and can achieve high signal-to-noise ratio, high efficiency and deep exploration, especially suitable for mineral resource exploration in complex terrain areas. The basic principle of transient electromagnetic method is to use an ungrounded loop or grounded wire to send a pulsed magnetic field underground, and detect underground structures by observing the time-varying characteristics of the secondary induced electromagnetic field generated by the underground medium. This method performs well in deep mineral exploration because it can effectively detect deep hidden ore bodies, and has good application prospects in areas where the conductivity difference between the surrounding rock and the ore body is obvious.

[0043] The geological background data of the research area include mineralization geological action, mineralization structural system, mineralization geological characteristics, and prospecting sign information. Furthermore, according to the stratigraphic, structural, lithological and physical characteristics, multiple survey lines are arranged in the overlying strata of the ore body. The principle of survey line arrangement is: one survey line has no less than two survey points, and the distance between two adjacent survey lines is 200m. Among them, the ground electromagnetic survey point is arranged above the ore body, and the airborne ground-to-air electromagnetic survey point is arranged between the ground and airborne electromagnetic survey points.

[0044] In the embodiment of the present invention, a total of 96 ground electromagnetic measurement points and 20 airborne ground-to-air electromagnetic measurement points were collected. The ground electromagnetic measurement points used the WY-D instrument, and the airborne ground-to-air electromagnetic measurement points used the WYGX-600 instrument. Both instruments have high-precision measurement capabilities and can achieve high-precision measurement.

[0045] Furthermore, in step S2, the ground-to-air electromagnetic detection data is preprocessed including cleaning, denoising, baseline correction, and off-time removal.

[0046] Specifically, the specific steps for denoising the ground-to-air electromagnetic detection data are as follows:

[0047] S21, segmenting the ground-to-air electromagnetic detection data to obtain single-point ground-to-air electromagnetic measurement data;

[0048] S22, preprocessing the ground-to-air electromagnetic measurement data using a weighted mean filtering method to extract the attenuation characteristics of the ground-to-air electromagnetic data;

[0049] S23, establishing an exponential fitting prediction equation according to the attenuation characteristics, performing an exponential fitting on the ground-to-air electromagnetic measurement data, and obtaining a fitting output result;

[0050] S24, establishing an adaptive scalar Kalman filter, inputting the fitting output result into the filter as a prediction value, filtering out electromagnetic noise, and extracting effective signals.

[0051] Furthermore, the Savitzky-Golay smoothing filter method is used for baseline correction.

[0052] Furthermore, in step S3, the specific steps of inverting the preprocessed data using the inversion algorithm are as follows:

[0053] S31, firstly, the underground space of the inversion area is divided into rectangular parallelepiped grids, the center coordinates and the corresponding side lengths of each grid unit are determined, and the distance parameters of each grid unit are determined;

[0054] S32, calculating the ground data kernel matrix and the aviation data kernel matrix corresponding to different measurement heights according to the total magnetization direction of the inversion area, the geomagnetic direction and the center coordinates and corresponding side lengths of each grid cell, and calculating the pre-optimization factor corresponding to each grid cell according to the corresponding distance parameter to generate a pre-optimization matrix;

[0055] S33, combining the ground data kernel matrix and the aviation data kernel matrix into a total kernel matrix, and combining all observation data into a total observation data matrix;

[0056] S34, establishing a joint inversion target equation based on the pre-optimized matrix, the total observation data matrix, and the total kernel matrix;

[0057] S35. Use the pre-optimized conjugate gradient algorithm to solve the joint inversion target equation and obtain the electrical structure model of the underground medium.

[0058] After completing the deep mineral prediction, it also includes deep verification of the determined mineral locations by arranging drill holes to complete the deep mineral prospecting process.

[0059] On the other hand, a deep prospecting system based on ground-to-air electromagnetic detection is provided. Figure 2 As shown, it includes a data acquisition module, a preprocessing module, an inversion module, and a prediction module; wherein,

[0060] The data acquisition module is used to obtain geological background information of the study area and conduct field surveys, determine the transmitting and receiving positions, carry out ground-to-air transient electromagnetic measurements at different flight altitudes, and obtain ground-to-air electromagnetic detection data;

[0061] A preprocessing module is used to preprocess the ground-to-air electromagnetic detection data to obtain preprocessed data;

[0062] An inversion module is used to invert the preprocessed data using an inversion algorithm to obtain an electrical structure model of the underground medium;

[0063] The prediction module is used to predict the distribution and characteristics of underground geological bodies and determine the location of minerals based on the electrical structure model.

[0064] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A deep prospecting method based on ground-to-air electromagnetic detection, characterized in that: The specific steps include the following: Obtain geological background information of the study area and conduct field surveys to determine the transmitting and receiving locations, conduct ground-to-air transient electromagnetic measurements at different flight altitudes, and obtain ground-to-air electromagnetic detection data; Preprocessing the ground-to-air electromagnetic detection data to obtain preprocessed data; Inverting the preprocessed data using an inversion algorithm to obtain an electrical structure model of the underground medium; Based on the electrical structure model, the distribution and characteristics of underground geological bodies can be predicted and the location of minerals can be determined.

2. A deep prospecting method based on ground-to-air electromagnetic detection according to claim 1, characterized in that: The preprocessing of the ground-to-air electromagnetic detection data includes cleaning, denoising, baseline correction, and off-time removal.

3. A deep prospecting method based on ground-to-air electromagnetic detection according to claim 2, characterized in that: The specific steps of denoising the ground-to-air electromagnetic detection data are as follows: Segmenting the ground-to-air electromagnetic detection data to obtain single-point ground-to-air electromagnetic measurement data; Preprocessing the ground-to-air electromagnetic measurement data using a weighted mean filtering method to extract attenuation characteristics of the ground-to-air electromagnetic data; Establishing an exponential fitting prediction equation according to the attenuation characteristics, performing an exponential fitting on the ground-to-air electromagnetic measurement data, and obtaining a fitting output result; An adaptive scalar Kalman filter is established, and the fitting output result is input into the filter as a prediction value to filter out electromagnetic noise and extract effective signals.

4. A deep prospecting method based on ground-to-air electromagnetic detection according to claim 2, characterized in that: The baseline correction was performed using the Savitzky-Golay smoothing filter method.

5. The deep prospecting method based on ground-to-air electromagnetic detection according to claim 1 is characterized in that: According to the characteristics of strata, structure, lithology and physical properties, multiple survey lines are arranged in the overlying strata of the ore body. The principle of survey line arrangement is: one survey line has no less than two measuring points, and the distance between two adjacent survey lines is 200m. The ground electromagnetic measuring points are arranged above the ore body, and the airborne ground-to-air electromagnetic measuring points are arranged between the ground and airborne electromagnetic measuring points.

6. A deep prospecting method based on ground-to-air electromagnetic detection according to claim 1, characterized in that: The specific steps of inverting the preprocessed data using the inversion algorithm are: Firstly, the underground space in the inversion area is divided into rectangular grids, the center coordinates and corresponding side lengths of each grid unit are determined, and the distance parameters of each grid unit are determined; The ground data kernel matrix and the aerial data kernel matrix corresponding to different measurement heights are calculated according to the total magnetization direction, geomagnetic direction and the center coordinates and corresponding side lengths of each grid cell in the inversion area, and the pre-optimization factor corresponding to each grid cell is calculated according to the corresponding distance parameter to generate the pre-optimization matrix; The ground data kernel matrix and the aerial data kernel matrix are combined into a total kernel matrix, and all observation data are combined into a total observation data matrix; Establishing a joint inversion objective equation based on the pre-optimized matrix, the total observation data matrix, and the total kernel matrix; The pre-optimized conjugate gradient algorithm is used to solve the joint inversion target equation to obtain the electrical structure model of the underground medium.

7. A deep prospecting method based on ground-to-air electromagnetic detection according to claim 1, characterized in that: The geological background data of the study area include metallogenic geological processes, metallogenic structural systems, metallogenic geological characteristics, and prospecting sign information.

8. The deep prospecting method based on ground-to-air electromagnetic detection according to claim 1 is characterized in that: It also includes the deployment of drill holes to conduct deep verification of the determined mineral locations to complete the deep mineral prospecting process.

9. A deep prospecting system based on ground-to-air electromagnetic detection, characterized in that: It includes data acquisition module, preprocessing module, inversion module and prediction module; among them, The data acquisition module is used to obtain geological background information of the research area and conduct field surveys, determine the transmitting and receiving positions, carry out ground-to-air transient electromagnetic measurements at different flight altitudes, and obtain ground-to-air electromagnetic detection data; The preprocessing module is used to preprocess the ground-to-air electromagnetic detection data to obtain preprocessed data; The inversion module is used to invert the preprocessed data using an inversion algorithm to obtain an electrical structure model of the underground medium; The prediction module is used to predict the distribution and characteristics of underground geological bodies and determine the location of mineral resources based on the electrical structure model.

Images