阅读说明：本技术 一种基于广域电磁法的砂岩型铀矿砂体识别方法及系统 (Sandstone-type uranium ore sand body identification method and system based on wide-area electromagnetic method ) 是由 汪硕 段书新 吴振宇 胡英才 吕孝勇 喻翔 于 2020-07-20 设计创作，主要内容包括：本发明涉及一种基于广域电磁法的砂岩型铀矿砂体识别方法及系统,所述识别方法包括：采集地浸砂岩型铀矿沉积盆地中沿剖面不同测点处电压值的时间序列；将所述不同测点处电压值的时间序列转换为视电阻率；对所述视电阻率进行反演计算,得到剖面下方电阻率随深度的分布断面；对所述分布断面进行深度的标定和校正；基于标定和校正后的分布断面对砂体进行划分。本发明中的上述方法能够提高适用性和探测精度。(The invention relates to a sandstone-type uranium ore sand body identification method and system based on a wide-area electromagnetic method, wherein the identification method comprises the following steps: collecting time sequences of voltage values at different measuring points along a section in a ground leaching sandstone type uranium deposit basin; converting the time series of voltage values at the different measuring points into apparent resistivity; performing inversion calculation on the apparent resistivity to obtain a distribution section of the resistivity below the section along with the depth; carrying out depth calibration and correction on the distribution section; and dividing the sand body based on the calibrated and corrected distribution section. The method can improve the applicability and the detection precision.)

1. A sandstone-type uranium ore sand body identification method based on a wide-area electromagnetic method is characterized by comprising the following steps:

collecting time sequences of voltage values at different measuring points along a section in a ground leaching sandstone type uranium deposit basin;

converting the time series of voltage values at the different measuring points into apparent resistivity;

performing inversion calculation on the apparent resistivity to obtain a distribution section of the resistivity below the section along with the depth;

carrying out depth calibration and correction on the distribution section;

and dividing the sand body based on the calibrated and corrected distribution section.

2. The method for identifying sandstone-type uranium ore sand bodies based on the wide-area electromagnetic method according to claim 1, wherein the collecting the time series of the voltage values at different measuring points along the section in the in-situ leaching type uranium ore deposit basin specifically comprises:

determining sampling points;

determining the frequency of a receiving end of a wide-area electromagnetic instrument;

distributing emitters of the wide-area electromagnetic instrument;

and acquiring a time sequence of voltage values by adopting a copper bar or a non-polarized electrode of the wide-area electromagnetic instrument on the sampling point.

3. The method for identifying sandstone-type uranium ore sand bodies based on the wide-area electromagnetic method according to claim 1, wherein the converting the time series of voltage values at the different measuring points into apparent resistivity specifically comprises:

determining resistivity and phase data of different frequencies of a single point;

deleting 'flying spot' data generated before the superposition of all frequency points in the resistivity and phase data of the single point with different frequencies;

acquiring point location data and emission current data of a measuring point;

and determining apparent resistivity based on the point location data of the measuring point, the emission current data and the resistivity and phase data of the single point with different frequencies after the flying spot data is deleted.

4. The method for identifying sandstone-type uranium ore sand bodies based on the wide-area electromagnetic method according to claim 3, wherein the following formula is adopted for determining resistivity and phase data of different frequencies of a single point:

where ρ is_aTo determine the apparent resistivity at the measurement point,

5. The method for identifying sandstone-type uranium ore sand bodies based on the wide-area electromagnetic method according to claim 1, wherein the step of performing inversion calculation on the apparent resistivity to obtain a distribution section of resistivity along with depth below a section specifically comprises the steps of:

deleting or translating discontinuous frequency points and frequency bands in the apparent resistivity;

carrying out static displacement correction on each measuring point on the whole section, and removing the interference of the uneven body at the shallow part on the single-point whole branch data;

performing inversion calculation on the apparent resistivity after the static displacement correction to obtain resistivity profile data taking the depth as a longitudinal axis and the horizontal distance as a transverse axis;

converting the depth in the resistivity profile data into elevation to obtain the resistivity profile data with the elevation as a longitudinal axis and the profile distance as a transverse axis;

interpolating the resistivity profile data with the elevation as a longitudinal axis and the profile distance as a transverse axis;

and whitening the interpolated resistivity profile data to obtain a distribution profile of the resistivity along with the depth.

6. The method for identifying sandstone-type uranium ore sand bodies based on the wide-area electromagnetic method according to claim 5, wherein the depth calibration and correction of the distribution profile specifically comprises:

and calibrating the depth in the resistivity profile data in the inversion result by adopting a linear fitting method according to the top-bottom interface depth of the corresponding sandstone, glutenite and conglomerate in the core record or resistivity logging curve result.

7. The method for identifying sandstone type uranium ore sand bodies based on the wide-area electromagnetic method according to claim 1, wherein the dividing of the sand bodies based on the calibrated and corrected distribution section specifically comprises:

and dividing the spreading form of the sand body on the whole section according to the characteristics of the horizontal continuity of the horizon, the consistency of adjacent sections and the like.

8. A sandstone-type uranium deposit sand body identification system based on a wide-area electromagnetic method is characterized by comprising the following steps:

the data acquisition module is used for acquiring time sequences of voltage values at different measuring points along a section in the ground-leaching sandstone-type uranium ore deposit basin;

the conversion module is used for converting the time series of the voltage values at the different measuring points into apparent resistivity;

the inversion calculation module is used for carrying out inversion calculation on the apparent resistivity to obtain a distribution section of the resistivity below the section along with the depth;

the calibration and correction module is used for carrying out depth calibration and correction on the distribution cross section;

and the dividing module is used for dividing the sand body based on the calibrated and corrected distribution section.

9. The system for identifying sandstone-type uranium ore sand bodies based on the wide-area electromagnetic method according to claim 8, wherein the data acquisition module specifically comprises:

a sampling point determining unit for determining a sampling point;

the receiving end frequency adjusting unit is used for determining the receiving end frequency of the wide-area electromagnetic instrument;

the emitter distributing unit is used for distributing emitters of the wide-area electromagnetic instrument;

and the time sequence acquisition unit of the voltage value is used for acquiring the time sequence of the voltage value by adopting a copper bar or a non-polarized electrode of the wide-area electromagnetic instrument on the sampling point.

10. The method for identifying sandstone-type uranium ore sand bodies based on the wide-area electromagnetic method according to claim 8, wherein the conversion module specifically comprises:

the resistivity and phase data determining unit is used for determining resistivity and phase data of the single point at different frequencies;

the flying spot data deleting unit is used for deleting flying spot data generated before superposition of all frequency points in the resistivity and phase data of the single point with different frequencies;

the point location data and emission current data acquisition unit is used for acquiring point location data and emission current data of the measuring point;

and the apparent resistivity determining unit is used for determining apparent resistivity based on the point location data of the measuring point, the emission current data and the resistivity and phase data of the single point with different frequencies after the flying point data is deleted.

Technical Field

The invention relates to the field of geophysical exploration, in particular to a sandstone-type uranium ore sand body identification method and system based on a wide-area electromagnetic method.

Background

The traditional ground-leaching sandstone-type uranium ore exploration usually adopts an audio magnetotelluric method, a magnetotelluric method or a controllable source audio magnetotelluric method to detect a deep mineralization environment and identify favorable sand bodies related to mineralization. The method reflects the electrical structure and characteristics of underground rocks and strata by receiving electromagnetic fields with different frequencies from natural fields or artificial emission.

In practical method application, due to the limit values of the traditional electromagnetic sounding methods in the calculation of the signal-to-noise ratio, the frequency point density and the apparent resistivity, the effect is difficult to achieve the precision required by exploration when the sandstone with small electrical property difference and thin thickness is identified. In order to further improve the deep exploration efficiency and enable the geophysical sounding method to play a greater role in sandstone-type uranium ores, a wide-area electromagnetic method detection technology is provided.

Disclosure of Invention

The invention aims to provide a sandstone-type uranium ore sand body identification method and system based on a wide-area electromagnetic method, and the applicability and the detection precision are improved.

In order to achieve the purpose, the invention provides the following scheme:

a sandstone-type uranium ore sand body identification method based on a wide-area electromagnetic method comprises the following steps:

collecting time sequences of voltage values at different measuring points along a section in a ground leaching sandstone type uranium deposit basin;

converting the time series of voltage values at the different measuring points into apparent resistivity;

performing inversion calculation on the apparent resistivity to obtain a distribution section of the resistivity below the section along with the depth;

carrying out depth calibration and correction on the distribution section;

and dividing the sand body based on the calibrated and corrected distribution section.

Optionally, the time sequence of collecting voltage values at different measuring points along a section in the ground-leached sandstone-type uranium deposit basin specifically includes:

determining sampling points;

determining the frequency of a receiving end of a wide-area electromagnetic instrument;

distributing emitters of the wide-area electromagnetic instrument;

and acquiring a time sequence of voltage values by adopting a copper bar or a non-polarized electrode of the wide-area electromagnetic instrument on the sampling point.

Optionally, the converting the time series of the voltage values at the different measuring points into the apparent resistivity specifically includes:

determining resistivity and phase data of different frequencies of a single point;

deleting 'flying spot' data generated before the superposition of all frequency points in the resistivity and phase data of the single point with different frequencies;

acquiring point location data and emission current data of a measuring point;

and determining apparent resistivity based on the point location data of the measuring point, the emission current data and the resistivity and phase data of the single point with different frequencies after the flying spot data is deleted.

Optionally, the following formula is adopted for determining the resistivity and phase data of the single point at different frequencies:

where ρ is_aTo determine the apparent resistivity at the measurement point,

is the device coefficient;for the voltage difference at the measuring point, the electric field intensity E at the measuring point_xMultiplying the receiving end electrode distance MN, wherein I is a power supply current;

for electromagnetic effect function, r is the transmit-receive distance, -ik ═ 1-i/, where is the wavenumber of the uniform half-space.

Optionally, the performing inversion calculation on the apparent resistivity to obtain a distribution section of the resistivity along with the depth below the section specifically includes:

deleting or translating discontinuous frequency points and frequency bands in the apparent resistivity;

carrying out static displacement correction on each measuring point on the whole section, and removing the interference of the uneven body at the shallow part on the single-point whole branch data;

performing inversion calculation on the apparent resistivity after the static displacement correction to obtain resistivity profile data taking the depth as a longitudinal axis and the horizontal distance as a transverse axis;

converting the depth in the resistivity profile data into elevation to obtain the resistivity profile data with the elevation as a longitudinal axis and the profile distance as a transverse axis;

interpolating the resistivity profile data with the elevation as a longitudinal axis and the profile distance as a transverse axis;

and whitening the interpolated resistivity profile data to obtain a distribution profile of the resistivity along with the depth.

Optionally, the depth calibration and correction of the distribution profile specifically includes:

and calibrating the depth in the resistivity profile data in the inversion result by adopting a linear fitting method according to the top-bottom interface depth of the corresponding sandstone, glutenite and conglomerate in the core record or resistivity logging curve result.

Optionally, dividing the sand body based on the calibrated and corrected distribution section specifically includes:

and dividing the spreading form of the sand body on the whole section according to the characteristics of the horizontal continuity of the horizon, the consistency of adjacent sections and the like.

The invention further provides a sandstone-type uranium ore sand body identification system based on a wide-area electromagnetic method, and the system comprises:

the data acquisition module is used for acquiring time sequences of voltage values at different measuring points along a section in the ground-leaching sandstone-type uranium ore deposit basin;

the conversion module is used for converting the time series of the voltage values at the different measuring points into apparent resistivity;

the inversion calculation module is used for carrying out inversion calculation on the apparent resistivity to obtain a distribution section of the resistivity below the section along with the depth;

the calibration and correction module is used for carrying out depth calibration and correction on the distribution cross section;

and the dividing module is used for dividing the sand body based on the calibrated and corrected distribution section.

Optionally, the data acquisition module specifically includes:

a sampling point determining unit for determining a sampling point;

the receiving end frequency adjusting unit is used for determining the receiving end frequency of the wide-area electromagnetic instrument;

the emitter distributing unit is used for distributing emitters of the wide-area electromagnetic instrument;

and the time sequence acquisition unit of the voltage value is used for acquiring the time sequence of the voltage value by adopting a copper bar or a non-polarized electrode of the wide-area electromagnetic instrument on the sampling point.

Optionally, the conversion module specifically includes:

the resistivity and phase data determining unit is used for determining resistivity and phase data of the single point at different frequencies;

the flying spot data deleting unit is used for deleting flying spot data generated before superposition of all frequency points in the resistivity and phase data of the single point with different frequencies;

the point location data and emission current data acquisition unit is used for acquiring point location data and emission current data of the measuring point;

and the apparent resistivity determining unit is used for determining apparent resistivity based on the point location data of the measuring point, the emission current data and the resistivity and phase data of the single point with different frequencies after the flying point data is deleted.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects:

according to the sandstone-type uranium ore sand body identification method and system based on the wide-area electromagnetic method, a wide-area electromagnetic data acquisition system is adopted to perform data acquisition, processing and inversion work on a sandstone-type uranium ore basin, the beneficial sand bodies related to ore formation are defined based on the advantages of the wide-area electromagnetic method in the frequency density, the signal-to-noise ratio and the apparent resistivity calculation formula of received data and the priori information correction technology by utilizing known drilling holes, so that the exploration risk is reduced, and the economic benefit of uranium ore exploration is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

Fig. 1 is a flow chart of a sandstone-type uranium ore sand body identification method based on a wide-area electromagnetic method according to an embodiment of the invention;

FIG. 2 is a schematic diagram illustrating a memorability depth correction of a wide-area electromagnetic result using a drill hole exposure result according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a sandstone-type uranium ore sand body identification system based on a wide-area electromagnetic method in the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a sandstone-type uranium ore sand body identification method and system based on a wide-area electromagnetic method, and the applicability and the detection precision are improved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Fig. 1 is a flowchart of a sandstone-type uranium ore sand body identification method based on a wide-area electromagnetic method, and as shown in fig. 1, the method includes:

step 101: and collecting time sequences of voltage values at different measuring points along the section in the ground-leaching sandstone type uranium deposit basin.

Specifically, the following points are included in the step 101:

step 1011: sample points are determined.

The electric field acquisition interval is 100 meters on the same section for continuous sampling, namely every 100 meters is taken as a sampling point. And a copper bar or a non-polarized electrode is adopted on each sampling point to be coupled with ground soil to acquire signals. When the copper rods are used for sampling at each sampling point, the copper rods are directly inserted into the ground as deep as possible, and when the resistance meter is used for measuring the grounding resistance between the two copper rods to be greater than 5000 omega, a saline pouring mode can be adopted to reduce the grounding resistance, so that the better coupling state of the copper rods and the soil is maintained. When a non-polarized electrode is adopted, a small pit with the depth of more than 10cm is dug firstly, soft and moist soil is kept at the bottom in the pit, impurities such as roots and stones are removed, the non-polarized electrode is moved into the pit, the bottom is in full contact with the soil, and the polar pit is covered with the soil after the non-polarized electrode is arranged.

Step 1012: and determining the frequency of the receiving end of the wide-area electromagnetic instrument.

I.e. the receiver side frequency combination is set. Since the sand distribution is related to the vertical resolution, the frequency density is as dense as possible during reception. When collecting, firstly, the lowest frequency value is selected according to the exploration task. The principle is the same as that of the conventional geoelectromagnetic method, and the specific operation steps are as follows:

a) defining the maximum burial depth of a target body, and selecting a numerical value slightly larger than the maximum burial depth as an exploration depth d;

b) average resistivity of the sensing area

The calculation method can be used for estimating the borehole resistivity logging curve and the section result measured by an electrical method according to experience or collected surrounding areas of the logging area;

c) exploration depth estimation formula according to frequency domain electromagnetic sounding methodThe lowest frequency f is calculated.

The lowest frequency required is then selected to all frequency groups within the highest frequency range that the device can transmit to, thereby obtaining single point data with the highest measured frequency density.

Step 1013: and arranging emitters of the wide-area electromagnetic instrument.

The distance from the position of the transmitting dipole to the nearest receiving point is required to be more than 3 times of the exploration depth, and the transmitting-receiving distance is more than 5 times of the actual arrangement. When the emitting electrodes are arranged, in order to ensure good power supply effect, the grounding resistance is generally required to be reduced as much as possible. The aluminum plates are arranged, the area of each aluminum plate is about 1 square meter, the aluminum plates are arranged in an array manner, and the direct distance between two dipoles is about 1-2 km.

Step 1014: and acquiring a time sequence of voltage values by adopting a copper bar or a non-polarized electrode of the wide-area electromagnetic instrument on the sampling point.

A JSDY-180 wide-area electromagnetic system is selected, and the launching system has the characteristics of high power and launching of pseudo-random waves. The current at the transmitter side in this example is typically greater than 150A. The selected receiver should have a high-sensitivity system for decoding the pseudorandom signal, and the receiver adopted in the example is a JSG-2 wide-area electromagnetic receiving system.

In order to ensure that the recorded electric field values of all receiving channels are stable, data of all frequency points of all channels are paid attention to in real time through acquisition software, and the deviation is not more than 10% when the data are overlapped for multiple times.

Step 102: and converting the time series of voltage values at the different measuring points into apparent resistivity.

The method specifically comprises the following steps:

step 1021: and determining resistivity and phase data of different frequencies of a single point.

Namely, synthesizing single-point data, loading data files of different frequency groups collected by the same measuring point, and then operating and merging the data files in software, so as to obtain resistivity and phase data of the single point at different frequencies, wherein the following formula is specifically adopted:

where ρ is_aTo determine the apparent resistivity at the measurement point,is the device coefficient;for the voltage difference at the measuring point, the electric field intensity E at the measuring point_xMultiplying the receiving end electrode distance MN, wherein I is a power supply current;for electromagnetic effect function, r is the transmit-receive distance, -ik ═ 1-i/, where is the wavenumber of the uniform half-space.

Step 1022: and deleting 'flying spot' data generated before the superposition of all frequency points in the resistivity and phase data of the single point with different frequencies.

That is, the data synthesized in step 1021 is loaded in the "point data processing", and the "flying spot" data generated before the superimposition of the respective frequency points is checked and deleted.

Step 1023: and acquiring point location data and emission current data of the measuring points.

Step 1024: and determining apparent resistivity based on the point location data of the measuring point, the emission current data and the resistivity and phase data of the single point with different frequencies after the flying spot data is deleted.

Specifically, point position data, emission current data and electric field data acquired by RTK are respectively imported into the apparent resistivity calculation, and then the calculation result is exported by clicking the starting calculation.

Step 103: and carrying out inversion calculation on the apparent resistivity to obtain a distribution section of the resistivity below the section along with the depth.

And (3) loading the apparent resistivity data calculated in the step (102) into WFEM 2D-Pro inversion software to perform inversion simulation calculation, thereby obtaining a distribution section of the resistivity below the profile along with the depth. The system is adopted to delete 'flying spots', correct, invert and form a map for wide-area electromagnetic two-dimensional data, the processing flow is similar to the magnetotelluric result commonly used in principle, and the specific steps are as follows:

step 1031: and deleting or translating discontinuous frequency points and frequency bands in the single-point curve data.

Step 1032: and then, performing static displacement correction on each measuring point on the whole section by using a correction function of software, and removing the interference of the shallow part of the non-uniform body on the single-point whole branch data.

Step 1033: the inversion calculation is automatically carried out by a computer after the parameter setting is finished. The main parameters adopted in the inversion process are as follows: the horizontal resolution index is 0.3-0.5; in the vertical resolution index, a value not greater than 1 is generally selected because more layering information is expected to be obtained in the sedimentary stratum; the number of inversion iterations is generally greater than 5; the inversion termination fitting difference is not easily larger than 10%. The resolution factors adopted in this example are 0.5 in the horizontal direction and 0.85 in the vertical direction, respectively. And (3) setting the inversion parameters in WFEM2D _ Pro software, and automatically performing iterative operation by clicking and running two-dimensional inversion to complete the inversion process.

Step 1034: after iterative inversion calculation, resistivity profile data with the depth as a longitudinal axis and the horizontal distance as a transverse axis is obtained, and the data format is horizontal distance/meter depth/meter resistivity/ohm meter.

Step 1035: the depth of the data result in step 1034 is converted to elevation using elevation data recorded from the field RTK.

Step 1036: and (4) interpolating the inversion result model file by using Surfer software by taking the vertical axis as elevation and the horizontal axis as section distance. And whitening the interpolated data by using elevation data recorded by RTK again to obtain a resistivity distribution characteristic profile with terrain.

Step 104: and carrying out depth calibration and correction on the distribution section.

More than one drill hole passing through the section or the vicinity of the section is obtained through data collection or self-testing, and the middle and high resistance electric layer position in the inversion result is calibrated and calibrated according to the core record or the positions of corresponding sandstone, glutenite and conglomerate in the resistivity logging curve result. The position of the top-bottom interface of the sandstone layer in this example corresponds to the range of the electrical layer position of 10-30 ohm meters in the resistivity distribution characteristic cross-section diagram obtained in the 1036 step in the step 103. The sand layer top-bottom interface depth [ D ] is recorded as (D1, D2, D3, D4 … Dn), and the section inversion resistivity layer top-bottom interface depth [ D ] is recorded as (D1, D2, D3, D4 … Dn) (as shown in fig. 2). When the number of the cross section layers does not accord with the actual editing result, a plurality of thin layers in the editing result can be regarded as a merging layer, and information of the top and bottom surfaces of the merging layer is recorded). And performing least square fitting on the two groups of data [ D ] and [ D ]. The step is realized by writing MATLAB codes, and the specific codes are as follows:

d ═ d1, d2, d3, d4, …, dn ]; % definition borehole exposure sandstone top-bottom interface

D ═ D1, D2, D3, D4, …, Dn ]; % definition inversion section inference sandstone top-bottom interface

[ a, b ] ═ polyfit (D, 1); % obtaining inversion result depth equation coefficients a, b

And substituting a column of data of 'depth' in the inversion result data obtained in the step 1034 in the step 103 into x for conversion on the obtained fitting equation y being ax + b, and replacing the original depth data with the obtained converted y data. The process of steps 1035 and 1036 is repeated again to redraw the profile resistivity profile.

Step 105: and dividing the sand body based on the calibrated and corrected distribution section.

And dividing a main sand body top and bottom interface by utilizing the resistivity section result and the interpretation principle obtained in the step 104 in a mode of tracing a region with a fast change along an isoline, dividing the high-resistance layer position spreading form on all sections of the whole measuring region according to the characteristics of transverse continuity of the layer position of the sedimentary region, consistency of adjacent sections and the like, marking the high-resistance layer position spreading form as sandstone-type uranium ore-forming favorable sand bodies, and finally obtaining required ore finding information from the sections, wherein the information mainly comprises the sand body thickness, the sand body top and bottom plate burial depth and the like.

Fig. 3 is a schematic structural diagram of a sandstone-type uranium ore sand body identification system based on a wide-area electromagnetic method in an embodiment of the present invention, and as shown in fig. 3, the system includes:

the data acquisition module 201 is used for acquiring time sequences of voltage values at different measuring points along a section in the ground-leaching sandstone-type uranium ore deposit basin;

a conversion module 202, configured to convert the time series of voltage values at different measurement points into apparent resistivity;

the inversion calculation module 203 is used for performing inversion calculation on the apparent resistivity to obtain a distribution section of the resistivity below the section along with the depth;

a calibration and correction module 204, configured to perform depth calibration and correction on the distribution profile;

and the dividing module 205 is used for dividing the sand body based on the calibrated and corrected distribution section.

The data acquisition module 201 specifically includes:

a sampling point determination unit 2011 configured to determine a sampling point;

the receiving end frequency adjusting unit 2012 is used for determining the receiving end frequency of the wide-area electromagnetic instrument;

the emitting electrode distributing unit 2013 is used for distributing emitting electrodes of the wide-area electromagnetic instrument;

and the time sequence acquisition unit 2014 of the voltage values is used for acquiring the time sequence of the voltage values by adopting a copper rod or a non-polarized electrode of the wide-area electromagnetic instrument on the sampling points.

The conversion module 202 specifically includes:

a resistivity and phase data determining unit 2021, configured to determine resistivity and phase data of a single point at different frequencies;

the flying spot data deleting unit 2022 is configured to delete the flying spot data generated before the superposition of the frequency points in the resistivity and phase data of the single point with different frequencies;

a point location data and emission current data obtaining unit 2023, configured to obtain point location data and emission current data of the measurement point;

the apparent resistivity determining unit 2024 is configured to determine apparent resistivity based on the station location data, the emission current data, and the resistivity and phase data of the single point with different frequencies after the "flying spot" data is deleted.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.