CN112666616A - Electric source mine transient electromagnetic method detection method - Google Patents

Electric source mine transient electromagnetic method detection method Download PDF

Info

Publication number
CN112666616A
CN112666616A CN202110023428.8A CN202110023428A CN112666616A CN 112666616 A CN112666616 A CN 112666616A CN 202110023428 A CN202110023428 A CN 202110023428A CN 112666616 A CN112666616 A CN 112666616A
Authority
CN
China
Prior art keywords
electric field
roadway
coal rock
electromagnetic field
electromagnetic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202110023428.8A
Other languages
Chinese (zh)
Inventor
苏本玉
于景邨
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China University of Mining and Technology CUMT
Original Assignee
China University of Mining and Technology CUMT
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by China University of Mining and Technology CUMT filed Critical China University of Mining and Technology CUMT
Priority to CN202110023428.8A priority Critical patent/CN112666616A/en
Publication of CN112666616A publication Critical patent/CN112666616A/en
Pending legal-status Critical Current

Links

Images

Abstract

The invention discloses a mine transient electromagnetic method for an electrical source, which is suitable for being used in a mine roadway. Firstly, arranging a long lead electric source in a mine roadway, exciting an electromagnetic field through an electrode, arranging an electric field sensor in the roadway on the other side of a working face to receive an electromagnetic field signal, and further detecting a water-rich area of the working face; the wire electrical source is detected for the contact current source, effectively reduces the interior metal interference of tunnel, improves the directionality of surveying, improves the rate of accuracy of surveying. The problem of insufficient energy emitted by a small coil is effectively solved, the problem of multi-solution of the 'mirror effect' of the whole space is improved, metal interference in a roadway is effectively reduced through a wire electrical source detected by a contact current source, the detection directionality is improved, and the detection accuracy is improved.

Description

Electric source mine transient electromagnetic method detection method
Technical Field
The invention relates to a detection method, in particular to a detection method of an electric source mine transient electromagnetic method used in a mine roadway, and belongs to the field of coal mining water inrush prevention and control.
Background
In the aspect of coal mine water inrush prevention and control, the transient electromagnetic method is widely applied, coal mine water inrush accidents are reduced, economic loss is reduced, and safety of people is guaranteed. The mine transient electromagnetic method is widely applied to the water prevention and control work of coal mines, is one of the main means of mine geophysical prospecting at present, but is limited by the construction space of underground roadways, and a multi-turn small loop overlapping or separating magnetic source device with the side length of 2-3m and the number of turns of 30-60 is a main device form of the mine transient electromagnetic method, but has the following technical bottlenecks. (1) The emitted magnetic moment is small, and the detection effective distance is short; (2) the shielding effect of the metal anchor net of the roadway is serious and the interference signal is strong; (3) the directional detection of geological anomalies is difficult. Wherein. The fundamental reason for the problems is that the transient electromagnetic method of the magnetic source of the multi-turn small loop is influenced by the construction environment of the underground roadway. At present, the environment of the underground mine roadway cannot be changed, the change of the construction mode and the source property is expected to relieve and eliminate the problems, and an electric source mine transient electromagnetic detection method is provided, is transmitted in one roadway and received in the other roadway and is used for detecting the water-rich disaster water source of a working face.
Disclosure of Invention
The invention has the following problems: aiming at the defects of the technology, the electrical source mine transient electromagnetic detection method can make up the problem of insufficient energy emitted by a small coil, can improve the multi-solution problem of the 'mirror effect' of the whole space, and can provide more reliable geological data for mine water prevention and control.
The technical scheme is as follows: in order to achieve the technical purpose, the transient electromagnetic detection method for the mine electric source comprises the following steps: laying a lead current source in a roadway arranged on one side of a working face coal rock layer along the trend of the roadway, arranging electric field sensors on the coal rock layer wall of the roadway arranged on the other side of the coal rock layer at intervals according to the trend of the roadway, and determining the number and the interval of the electric field sensors according to the length of the working face coal rock layer; the wire current source transmits an electromagnetic field signal to a working face coal rock layer under the control of the industrial and mining host, the transmitted electromagnetic field signal is a primary electromagnetic field signal, a secondary electromagnetic field signal carrying stratum information is formed after the primary electromagnetic field signal meets a low-resistance abnormal body, the secondary electromagnetic field signal penetrates through the whole working face coal rock layer and is received by an electromagnetic field sensor arranged on the wall of the coal rock layer, the electromagnetic field sensor only receives the secondary electromagnetic field signal, and the electromagnetic field sensor transmits the received secondary electromagnetic field signal to the industrial and mining host, so that the specific position and the profile shape of the low-resistance abnormal body in the coal rock layer are confirmed.
The low-resistance abnormal body is water contained in the coal rock layer, the water serving as the good-conductivity geological body can generate induction secondary signals when encountering a primary electromagnetic field signal, and after the detection data carrying the good-conductivity geological body are processed and interpreted, whether the conductive body exists in the driving working face or not and the relative size and relative position information of the abnormal body are judged, so that early warning of underground construction is realized, and water damage of a mine is avoided.
The two ends of the wire current source are A and B, the two ends A and B of the wire current source are embedded on the side wall of a working face by using electrodes during arrangement, meanwhile, a plurality of electromagnetic field sensors which are arranged in another roadway at intervals along the direction of the roadway send received secondary electromagnetic field signals to the industrial and mining host, each electromagnetic field sensor sends signals to the industrial and mining host, the signals sent to the industrial and mining host all comprise the time received by the secondary electromagnetic field signals and the received electric field information, and the industrial and mining host utilizes a formula:
Figure BDA0002889516860000021
converting the secondary electromagnetic field signal and the receiving time sequence into depth, wherein t is observation time, rho is background field resistivity, pi is constant circumferential rate, and omega is angular frequency: ω ═ 100 π ρ t/(μ0L2)]1/4L is the length of the electrical source of the conducting wire, d (t) is the depth of view obtained by calculating the corresponding time, namely the depth corresponding to the time; the industrial and mining host machine utilizes a formula:
Figure BDA0002889516860000022
converting the electric field information into apparent resistivity of the coal and rock formations, wherein rhoaApparent resistance for switching, p1The resistivity of the uniform background field is uniform,
Figure BDA0002889516860000023
is a theoretical calculation of the background field, ExMeasuring an electric field value for the electric field sensor;
through the conversion, the time for receiving the signals is converted into the detection depth, the electric field signals are converted into the coal rock resistivity information, and the purpose of detecting the resistivity distribution in the coal rock stratum is finally achieved.
Because the electric source is adopted for detection and the electric field sensor is adopted, the detection directivity is stronger, and the interference of metal in the roadway is weakened.
The method for determining the position of the low-resistance abnormal body in the coal rock comprises the following steps:
according to mine geological data, researching the stratum attitude of a coal rock layer, designing an electric source mine transient electromagnetic observation system according to the characteristics of the stratum attitude, paving a cable in a roadway on one side of a working face coal rock layer in the whole process, connecting the cable with an electric source to form a lead electric source for transmitting an electromagnetic signal, and paving a plurality of electric field sensors on the roadway coal wall on the other side of the working face coal rock layer at intervals; the industrial and mining host is used as a host of transient electromagnetism of an electrical source, is connected with the electric field sensor through a cable and is used for recording and storing electric field information received by the electric field sensor; the electric field sensors are linearly arranged at intervals in the roadway, after the electric field sensors receive information, each electric field sensor records the received information into two parts, namely time and an electric field, converts the time into visual depth vertical to the linear arrangement, converts the corresponding electric field into visual resistance, further obtains a position chart with the total coordinate as depth and the abscissa as linear arrangement, namely receives the position chart of the sensors, and the chart displays the visual resistivity distribution; and obtaining the accurate position of the low-resistance abnormal body in the coal rock according to the picture.
In particular, the method comprises the following steps of,
i, storing electric field information received by an electric field sensor in a form of [ time, electric field ], wherein the electric field is provided with a plurality of channel maps;
and II, performing apparent conductivity conversion on the measured electric field component data to obtain geoelectric information in different directions, and performing comprehensive geological interpretation on the geologic body by integrating the existing geoelectric information.
Has the advantages that: compared with the traditional transient electromagnetic method with the multiple turns of small loops, the method has the advantages that the electric source of the conducting wire is laid in the roadway, the electric source of the conducting wire is detected by a contact type current source, and the directionality is good; a plurality of electromagnetic field sensors are arranged in the roadway on the other side of the coal rock layer relative to the electric source of the lead in a facing manner, the electric field sensors are in contact with the rock wall of the roadway, electric field signals are received, whether low-resistance abnormal bodies exist in the coal rock layer or not can be quickly determined through the received information, the position of the low-resistance abnormal bodies is required to be accurately obtained, and meanwhile interference signals are effectively reduced.
Drawings
FIG. 1 is a schematic layout diagram of the detection method of the electric source mine transient electromagnetic method of the invention;
FIG. 2 is a multi-channel data diagram of electric field values detected by the electrical source mine transient electromagnetic method of the present invention;
FIG. 3 is a diagram of electrical source mine transient electromagnetic resistivity profile of the present invention;
FIG. 4 is a schematic flow chart of the electric source mine transient electromagnetic method of the present invention.
Detailed description of the invention
The invention will be further described with reference to the following examples in which the accompanying drawings are set forth in detail:
as shown in fig. 1 and 4, the transient electromagnetic detection method for the mine electrical source of the invention comprises the following steps: firstly, collecting hydrogeological data and mine roadway data of a detection area, and according to mine geological characteristics such as topographic relief in a roadway, designing how to arrange a transmitting source and arrange a receiving sensor to complete the design of a detection scheme; and then, constructing the detection scheme on a working face: firstly, laying a lead current source in a roadway arranged on one side of a coal rock layer of a working face along the trend of the roadway, laying an electric field sensor on the wall of the coal rock layer of the roadway arranged on the other side of the coal rock layer at intervals of 5 meters according to the trend of the roadway, detecting by adopting an electric source and adopting the electric field sensor, and further strengthening the detection directivity and weakening the interference of metal in the roadway; the number of the electric field sensors is determined by the length of the coal rock layer of the working face; wherein the wire current source is under the control of industrial and mining host computer to the working face coal rock stratum transmission electromagnetic field signal, and the electromagnetic field signal at this moment is primary electromagnetic field signal, forms the secondary electromagnetic field signal that carries the stratum information after the primary electromagnetic field signal meets the low resistance abnormal body, and the secondary electromagnetic field signal is received by electromagnetic field sensor after penetrating whole working face coal rock stratum, utilizes transient electromagnetic method characteristics: the electromagnetic field sensor only receives a secondary field, during detection, the primary field is closed, namely measurement is carried out at the moment of primary closing, the electromagnetic field sensor sends received secondary electromagnetic field signals to the industrial and mining host, so that the specific position and the outline shape of a low-resistance abnormal body in a coal rock layer are confirmed, the low-resistance abnormal body contains water in the coal rock layer, the water serving as a good-conductivity geological body can generate induction secondary signals when encountering the primary electromagnetic field signals, and after detection data carrying the good-conductivity geological body are processed and interpreted, whether a normal body exists in a tunneling working face or not and the relative size and relative position information of the abnormal body are judged, so that early warning of underground construction is achieved, and mine water damage is avoided.
The two ends of the wire current source are A and B, the two ends A and B of the wire current source are embedded on the side wall of a working face by using electrodes during arrangement, meanwhile, a plurality of electromagnetic field sensors which are arranged in another roadway at intervals along the direction of the roadway send received secondary electromagnetic field signals to the industrial and mining host, each electromagnetic field sensor sends signals to the industrial and mining host, the signals sent to the industrial and mining host all comprise the time received by the secondary electromagnetic field signals and the received electric field information, and the industrial and mining host utilizes a formula:
Figure BDA0002889516860000031
converting the secondary electromagnetic field signal and the receiving time sequence into depth, wherein t is observation time, rho is background field resistivity, pi is constant circumferential rate, and omega is angular frequency: ω ═ 100 π ρ t/(μ0L2)]1/4L is the length of the electrical source of the conducting wire, d (t) is the depth of view obtained by calculating the corresponding time, namely the depth corresponding to the time; the industrial and mining host machine utilizes a formula:
Figure BDA0002889516860000041
converting the electric field information into apparent resistivity of the coal and rock formations, wherein rhoaApparent resistance for switching, p1The resistivity of the uniform background field is uniform,
Figure BDA0002889516860000042
is a theoretical calculation of the background field, ExMeasuring an electric field value for the electric field sensor; through the conversion, the time for receiving the signals is converted into the detection depth, the electric field signals are converted into the coal rock resistivity information, and the purpose of detecting the resistivity distribution in the coal rock stratum is finally achieved.
The method for determining the position of the low-resistance abnormal body in the coal rock comprises the following steps:
according to mine geological data, researching the stratum attitude of a coal rock layer, designing an electric source mine transient electromagnetic observation system according to the characteristics of the stratum attitude, paving a cable in a roadway on one side of a working face coal rock layer in the whole process, connecting the cable with an electric source to form a lead electric source for transmitting an electromagnetic signal, and paving a plurality of electric field sensors on the roadway coal wall on the other side of the working face coal rock layer at intervals; the industrial and mining host is used as a host of transient electromagnetism of an electrical source, is connected with the electric field sensor through a cable and is used for recording and storing electric field information received by the electric field sensor; the electric field sensors are linearly arranged at intervals in the roadway, after the electric field sensors receive information, each electric field sensor records the received information into two parts, namely time and an electric field, converts the time into visual depth vertical to the linear arrangement, converts the corresponding electric field into visual resistance, further obtains a position chart with the total coordinate as depth and the abscissa as linear arrangement, namely receives the position chart of the sensors, and the chart displays the visual resistivity distribution; and obtaining the accurate position of the low-resistance abnormal body in the coal rock according to the picture.
I, storing electric field information received by an electric field sensor in a form of [ time, electric field ], wherein the electric field is provided with a plurality of channel maps; referring to fig. 2, a schematic diagram of multiple tracks receiving an electric field by using a contact type electric field sensor is shown.
II, performing apparent conductivity conversion on the measured electric field component data to obtain geoelectric information in different directions, and performing comprehensive geological interpretation on the geologic body by integrating the existing geoelectric information; specifically, as shown in fig. 3, for the measured electric field data, time information is converted into depth information, electric field information is converted into resistivity information, and the converted data is plotted into a view resistivity profile, so that the distribution of the rich water region can be analyzed.

Claims (6)

1. A mine electric source transient electromagnetic detection method is characterized by comprising the following steps: laying a lead current source in a roadway arranged on one side of a working face coal rock layer along the trend of the roadway, arranging electric field sensors on the coal rock layer wall of the roadway arranged on the other side of the coal rock layer at intervals according to the trend of the roadway, and determining the number and the interval of the electric field sensors according to the length of the working face coal rock layer; the wire current source transmits an electromagnetic field signal to a working face coal rock layer under the control of the industrial and mining host, the transmitted electromagnetic field signal is a primary electromagnetic field signal, a secondary electromagnetic field signal carrying stratum information is formed after the primary electromagnetic field signal meets a low-resistance abnormal body, the secondary electromagnetic field signal penetrates through the whole working face coal rock layer and is received by an electromagnetic field sensor arranged on the wall of the coal rock layer, the electromagnetic field sensor only receives the secondary electromagnetic field signal, and the electromagnetic field sensor transmits the received secondary electromagnetic field signal to the industrial and mining host, so that the specific position and the profile shape of the low-resistance abnormal body in the coal rock layer are confirmed.
2. The mine electrical source transient electromagnetic detection method of claim 1, wherein: the low-resistance abnormal body is water contained in the coal rock layer, the water serving as the good-conductivity geological body can generate induction secondary signals when encountering a primary electromagnetic field signal, and after the detection data carrying the good-conductivity geological body are processed and interpreted, whether the conductive body exists in the driving working face or not and the relative size and relative position information of the abnormal body are judged, so that early warning of underground construction is realized, and water damage of a mine is avoided.
3. The electrical source mine transient electromagnetic detection method of claim 1, wherein: the two ends of the wire current source are A and B, the two ends A and B of the wire current source are embedded on the side wall of a working face by using electrodes during arrangement, meanwhile, a plurality of electromagnetic field sensors which are arranged in another roadway at intervals along the direction of the roadway send received secondary electromagnetic field signals to the industrial and mining host, each electromagnetic field sensor sends signals to the industrial and mining host, the signals sent to the industrial and mining host all comprise the time received by the secondary electromagnetic field signals and the received electric field information, and the industrial and mining host utilizes a formula:
Figure FDA0002889516850000011
converting the secondary electromagnetic field signal and the receiving time sequence into depth, wherein t is observation time, rho is background field resistivity, pi is constant circumferential rate, and omega is angleFrequency: ω ═ 100 π ρ t/(μ0L2)]1/4L is the length of the electrical source of the conducting wire, d (t) is the depth of view obtained by calculating the corresponding time, namely the depth corresponding to the time; the industrial and mining host machine utilizes a formula:
Figure FDA0002889516850000012
converting the electric field information into apparent resistivity of the coal and rock formations, wherein rhoaApparent resistance for switching, p1The resistivity of the uniform background field is uniform,
Figure FDA0002889516850000013
is a theoretical calculation of the background field, ExMeasuring an electric field value for the electric field sensor;
through the conversion, the time for receiving the signals is converted into the detection depth, the electric field signals are converted into the coal rock resistivity information, and the purpose of detecting the resistivity distribution in the coal rock stratum is finally achieved.
4. The electrical source mine transient electromagnetic method of claim 1, wherein: because the electric source is adopted for detection and the electric field sensor is adopted, the detection directivity is stronger, and the interference of metal in the roadway is weakened.
5. The electrical source mine transient electromagnetic method of claim 1, 3 or 4, wherein the method for determining the position of the low-resistance abnormal body in the coal rock comprises the following steps:
according to mine geological data, researching the stratum attitude of a coal rock layer, designing an electric source mine transient electromagnetic observation system according to the characteristics of the stratum attitude, paving a cable in a roadway on one side of a working face coal rock layer in the whole process, connecting the cable with an electric source to form a lead electric source for transmitting an electromagnetic signal, and paving a plurality of electric field sensors on the roadway coal wall on the other side of the working face coal rock layer at intervals; the industrial and mining host is used as a host of transient electromagnetism of an electrical source, is connected with the electric field sensor through a cable and is used for recording and storing electric field information received by the electric field sensor; the electric field sensors are linearly arranged at intervals in the roadway, after the electric field sensors receive information, each electric field sensor records the received information into two parts, namely time and an electric field, converts the time into visual depth vertical to the linear arrangement, converts the corresponding electric field into visual resistance, further obtains a position chart with the total coordinate as depth and the abscissa as linear arrangement, namely receives the position chart of the sensors, and the chart displays the visual resistivity distribution; and obtaining the accurate position of the low-resistance abnormal body in the coal rock according to the picture.
6. The electromagnetic method of electrical source mine transients as claimed in claim 5, characterised in that specifically:
i, storing electric field information received by an electric field sensor in a form of [ time, electric field ], wherein the electric field is provided with a plurality of channel maps;
and II, performing apparent conductivity conversion on the measured electric field component data to obtain geoelectric information in different directions, and performing comprehensive geological interpretation on the geologic body by integrating the existing geoelectric information.
CN202110023428.8A 2021-01-08 2021-01-08 Electric source mine transient electromagnetic method detection method Pending CN112666616A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110023428.8A CN112666616A (en) 2021-01-08 2021-01-08 Electric source mine transient electromagnetic method detection method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110023428.8A CN112666616A (en) 2021-01-08 2021-01-08 Electric source mine transient electromagnetic method detection method

Publications (1)

Publication Number Publication Date
CN112666616A true CN112666616A (en) 2021-04-16

Family

ID=75413805

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110023428.8A Pending CN112666616A (en) 2021-01-08 2021-01-08 Electric source mine transient electromagnetic method detection method

Country Status (1)

Country Link
CN (1) CN112666616A (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104375194A (en) * 2014-11-10 2015-02-25 山东能源集团有限公司 Electrical source transient electromagnetic exploration method in water-rich area of deep mining mine
CN106772644A (en) * 2016-12-14 2017-05-31 中国矿业大学 mine transient electromagnetic three-component detection method
CN107807395A (en) * 2017-10-27 2018-03-16 中国矿业大学 Three-dimensional double magnetic source detection method above and below Mine transient electromagnetic well
CN107861159A (en) * 2017-10-19 2018-03-30 中煤科工集团西安研究院有限公司 Double Electric Dipole ground well transient electromagnetic detecting methods
CN108828676A (en) * 2018-04-18 2018-11-16 中国矿业大学 A kind of ground-mine laneway transient electromagnetic three-component detection method
US20200003928A1 (en) * 2018-07-02 2020-01-02 Institute Of Geology And Geophysics, Chinese Academy Of Sciences Method and device for surface-borehole transient electromagnetic detection

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104375194A (en) * 2014-11-10 2015-02-25 山东能源集团有限公司 Electrical source transient electromagnetic exploration method in water-rich area of deep mining mine
CN106772644A (en) * 2016-12-14 2017-05-31 中国矿业大学 mine transient electromagnetic three-component detection method
CN107861159A (en) * 2017-10-19 2018-03-30 中煤科工集团西安研究院有限公司 Double Electric Dipole ground well transient electromagnetic detecting methods
CN107807395A (en) * 2017-10-27 2018-03-16 中国矿业大学 Three-dimensional double magnetic source detection method above and below Mine transient electromagnetic well
CN108828676A (en) * 2018-04-18 2018-11-16 中国矿业大学 A kind of ground-mine laneway transient electromagnetic three-component detection method
US20200003928A1 (en) * 2018-07-02 2020-01-02 Institute Of Geology And Geophysics, Chinese Academy Of Sciences Method and device for surface-borehole transient electromagnetic detection

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
薛国强等: "电性源短偏移距瞬变电磁研究进展", 《中国矿业大学学报》 *

Similar Documents

Publication Publication Date Title
CN101706585B (en) Method for electrically forecasting danger in underground tunneling engineering
CN106772644B (en) mine transient electromagnetic three-component detection method
Bu et al. Application of the comprehensive forecast system for water-bearing structures in a karst tunnel: a case study
CN107861159A (en) Double Electric Dipole ground well transient electromagnetic detecting methods
CN103995296A (en) Transient electromagnetic method ground hole detection method and device
CN106054258A (en) Magnetic source ground-tunnel transient electromagnetic advanced detection method
CN104597511A (en) Transient electromagnetic detection method for ground-roadway of multi-layer goaf
CN111123365B (en) Goaf lagging water inrush early warning system based on natural potential method and application method thereof
CN104614779B (en) A kind of multi-parameter electromagnetic method dynamic monitoring system and its method
CN103967476A (en) Drilling geophysical prospecting advanced detecting device and method
CN103630946A (en) Single-hole electromagnetic wave tomography advanced detection device and method
CN105842740A (en) Fixed point rotary irradiation large power transient electromagnetic method
CN103499841A (en) Roadway-hole transient electromagnetic device and measuring method
CN107884834A (en) Homologous more transient electromagnetic detecting methods
CN103235344B (en) Two lanes multi-electrode electricity perspective detection system
CN102236105A (en) Omnibearing direct current method
Su et al. Progressive fine integrated geophysical method for karst detection during subway construction
CN105842738B (en) A kind of buried target body quantitatively judges method and apparatus extremely
CN103176214A (en) Electric field restraining method coal safety type fully-mechanized excavating onboard geological structure detection system and method thereof
Jiang et al. Prediction technology of buried water-bearing structures in coal mines using transient electromagnetic method
CN113093292A (en) Method for grouting coal seam roof through ground-hole transient electromagnetic monitoring
CN103499838B (en) The Transient electromagnetic measure device of anomalous body orientation recognition and recognition methods thereof
CN110989001A (en) Pile foundation three-dimensional drilling CT detection method applying HDD technology
CN103176216A (en) Pipeline detection method and borehole antenna
CN112666616A (en) Electric source mine transient electromagnetic method detection method

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination