Transient electromagnetic detection method for cross-hole electrical source mine

Abstract

The invention discloses a cross-hole electrical source mine transient electromagnetic detection method, and relates to the technical field of mine geophysical exploration, and the method comprises the steps: placing an electrical source comprising an electrode A and an electrode B in a drill hole for transmitting an electric field signal, and placing a receiving coil in another drill hole for sensing the internal information of a stratum; according to the drilling depth, the length of an emission source is designed, and the positions of A and B are determined; the A and the B are connected with a transient electromagnetic instrument through wires, and the transient electromagnetic instrument controls opening and closing of the A and the B; receiving positions and the number of receiving points are designed according to the length of the receiving drill hole and the exploration mine geological task; a receiving coil is connected with a transient electromagnetic instrument through a wire, opening and closing of a receiving sensor are controlled, and it is ensured that when an emission source is closed, the receiving sensor is opened, and a secondary field is received; the magnetic probe carries a crawler to obtain secondary field information at different positions. The method is large in detection range, high in information signal-to-noise ratio and high in precision, and can avoid potential safety hazards.

Description

Technical Field

[0001] The present invention relates to the technical field of mine geophysical detection, and in particular to a cross-hole electrical source mine transient electromagnetic detection method. Background Art

[0002] Safety has always been a major concern in mining projects, with water damage causing the most severe economic losses and casualties. Driven by the need for water prevention and control in coal mines, transient electromagnetic (TEM) technology was introduced in 1998. Drawing on electromagnetic theory and experiments, many scholars have provided valuable theoretical foundations for the technology's detection methods and subsequent processing and interpretation.

[0003] Downhole geophysical exploration technology allows for close proximity to the target object, and due to the shielding effect of the strata, it can effectively shield the electromagnetic noise of mine tunnels, thereby obtaining a high signal-to-noise ratio signal with high detection accuracy. It can also perform high-precision detection of water-conducting fracture zones in the strata, and downhole geophysical technology has broad application prospects in the mining industry. However, the current cross-hole transient electromagnetic method is a magnetic source transient electromagnetic detection method, which uses an in-hole coil for transmission and a in-hole coil for reception. Due to the small space in the hole, the magnetic moment of the transmitting coil is limited, and the detection range is very small, which is difficult to meet the requirements of mines.

[0004] Therefore, it is urgent to study a detection method to expand the detection range of cross-hole transient electromagnetic. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention discloses a cross-hole electrical source mine transient electromagnetic detection method, in which electrical sources A and B are placed in one borehole to emit a primary electric field into the formation, and the probe is placed in another borehole to receive the secondary magnetic field from the formation. High-resolution detection of disaster-prone water-rich geological bodies between the two boreholes can be performed.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A cross-hole electrical source mine transient electromagnetic detection method comprises the following steps:

[0008] S1. Placing an electrical source including electrodes A and B into a borehole for transmitting electric field signals, and placing a receiving coil into another borehole for sensing internal formation information;

[0009] S2. Design the length of the emission source and determine the positions of A and B according to the drilling depth;

[0010] S3. Use wires to connect A and B to a transient electromagnetic instrument, which controls the opening and closing of A and B.

[0011] S4. Design the receiving position and number of receiving points based on the length of the receiving borehole and the geological mission of the exploration mine;

[0012] S5. Use a wire to connect the receiving coil to the transient electromagnetic instrument, control the opening and closing of the receiving sensor, and ensure that the sensor is turned on during the period when the transmitting source is turned off, and the received field is the secondary field;

[0013] S6. Mount the magnetic probe on the crawler to obtain secondary field information at different locations.

[0014] Optionally, the detection method includes the steps of data preprocessing and data processing.

[0015] Optionally, the data preprocessing step includes normalization and denoising.

[0016] Optionally, the data processing step includes constructing a geological model, data inversion and three-dimensional imaging.

[0017] Optionally, the magnetic probe includes an x-component, a y-component and a z-component.

[0018] Optionally, the crawler includes a plurality of driving wheels for driving the crawler to move.

[0019] The beneficial effects of the present invention are as follows: the cross-hole electrical source mine transient electromagnetic detection method of the present invention places electrical sources A and B in one borehole, transmits a primary electric field into the stratum through electrodes, and places a receiving probe in another borehole to sense the magnetic field from the stratum. This method has the characteristics of a large detection range, a high signal-to-noise ratio of the detection information, and high detection accuracy. It greatly improves the detection accuracy of existing technologies, can avoid safety hazards to a certain extent, and can provide reliable data for personnel in coal mine departments, thereby improving the safety and economic benefits of coal mine production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the cross-hole electrical source mine transient electromagnetic detection method;

[0021] Figure 2 is a schematic diagram of the magnetic probe device;

[0022] Figure 3 It is a magnetic field sensor unit module;

[0023] Figure 4 Flowchart for processing and interpretation of cross-hole electrical source transient electromagnetic data. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] A cross-hole electrical source mine transient electromagnetic detection method, such as Figure 1-4 As shown, the following steps are included:

[0026] S1. Placing an electrical source including electrodes A and B into a borehole for transmitting electric field signals, and placing a receiving coil into another borehole for sensing internal formation information;

[0027] S2. Design the length of the emission source and determine the positions of A and B according to the drilling depth;

[0028] S3. Use wires to connect A and B to a transient electromagnetic instrument, which controls the opening and closing of A and B.

[0029] S4. Design the receiving position and number of receiving points based on the length of the receiving borehole and the geological mission of the exploration mine;

[0030] S5. Use a wire to connect the receiving coil to the transient electromagnetic instrument, control the opening and closing of the receiving sensor, and ensure that the sensor is turned on during the period when the transmitting source is turned off, and the received field is the secondary field;

[0031] S6. Mount the magnetic probe on the crawler to obtain secondary field information at different locations.

[0032] Optionally, the detection method includes the steps of data preprocessing and data processing.

[0033] Optionally, the data preprocessing step includes normalization and denoising.

[0034] Optionally, the data processing step includes constructing a geological model, data inversion and three-dimensional imaging.

[0035] Optionally, the magnetic probe includes an x-component, a y-component and a z-component.

[0036] Optionally, the crawler includes a plurality of driving wheels for driving the crawler to move.

[0037] The method of this embodiment is to place the receiving and transmitting sensors in two boreholes respectively, and use the transmitting sensor to transmit an electric field into the stratum. The sensor located in the other hole senses the information from the stratum, and by analyzing the signal in the receiving sensor, the resistivity distribution information between the two holes is obtained, thereby evaluating the mine disaster water. Compared with the traditional cross-hole transient electromagnetic, the method of the present invention has the following two significant features: (1) The present invention is a cross-hole electrical source mine transient electromagnetic detection method, and the transmitting sensor transmits a primary electric field signal; (2) The electrical source transmitting sensor uses electrodes A and B to transmit the electric field, and the distance between A and B can be set according to the depth of the borehole. This method detects the distance between the depth and AB. Compared with the traditional method, the detection distance is greatly increased, and the detection range can reach 100 meters.

[0038] The method of the present invention eliminates the need for specialized geological drilling and can be performed using water exploration holes in mine tunnels, saving construction costs and improving work efficiency. The method utilizes in-hole excitation and in-hole reception, away from the tunnel space, avoiding electromagnetic interference from the tunnel environment. This method can obtain data with a high signal-to-noise ratio, significantly improving the detection accuracy of existing technologies. It can provide reliable data to personnel in coal mines, thereby improving the safety and economic benefits of coal mine production.

[0039] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A cross-hole electrical source mine transient electromagnetic detection method, characterized in that: The steps include: S1. Placing an electrical source including electrodes A and B into a borehole for transmitting electric field signals, and placing a receiving coil into another borehole for sensing internal formation information; S2. Design the length of the emission source and determine the positions of A and B according to the drilling depth; S3. Use wires to connect A and B to a transient electromagnetic instrument, which controls the opening and closing of A and B. S4. Design the receiving position and number of receiving points based on the length of the receiving borehole and the geological mission of the exploration mine; S5. Use a wire to connect the receiving coil to the transient electromagnetic instrument, control the opening and closing of the receiving sensor, and ensure that the sensor is turned on during the period when the transmitting source is turned off, and the received field is the secondary field; S6. Mount the magnetic probe on the crawler to obtain secondary field information at different locations.

2. A cross-hole electrical source mine transient electromagnetic detection method according to claim 1, characterized in that: The detection method includes the steps of data preprocessing and data processing.

3. A cross-hole electrical source mine transient electromagnetic detection method according to claim 2, characterized in that: The data preprocessing steps include normalization and denoising.

4. A cross-hole electrical source mine transient electromagnetic detection method according to claim 3, characterized in that: The data processing steps include building geological models, data inversion and three-dimensional imaging.

5. The method for cross-hole electrical source mine transient electromagnetic detection according to claim 1, characterized in that: The magnetic probe includes an x-component, a y-component, and a z-component.

6. A cross-hole electrical source mine transient electromagnetic detection method according to claim 1, characterized in that: The crawler includes a plurality of driving wheels for driving the crawler to move.

Images