Gas extraction regulation method for working face front mining influence area

Abstract

The gas extraction regulation and control method of the working face front mining influence area disclosed by the application is according to the following steps, 1) determining the dynamic change range of the original stress area, the stress concentration area and the pressure relief area under the condition of the normal mining speed according to the field data; 2) establishing a numerical model of the stress dynamic change area of the coal body in front of the working face to determine the stress change area range in front of the working face; 3) determining the group hole arrangement scheme of the gas extraction regulation and control area; 4) using the gas extraction regulation and control method based on the pressure relief area in front of the working face to extract; 5) determining the gas extraction regulation and control data transmission valve control scheme. The problems of the prior art that the existing gas extraction regulation and control completely depends on human experience, the extraction regulation and control is not accurate, the gas extraction is low in efficiency and there are safety risks are solved.

Description

Technical Field

[0001] This invention belongs to the field of coal seam gas control technology, and relates to a method for controlling gas extraction in the mining-affected area ahead of the working face. Background Technology

[0002] Gas is considered a major cause of coal mine accidents and seriously restricts safe production in mines. Gas drainage is one of the most effective means of gas disaster management. In the process of mining coal seams in high-gas mines and coal and gas outburst mines, in-seam drilling is often used to pre-drain coal seam gas in front of the working face.

[0003] As the working face advances, the coal and rock mass ahead is affected by mining-induced stress, forming a typical three-zone structure consisting of the original stress zone, stress concentration zone, and decompression zone. Among these, the decompression zone, due to the release of mining-induced stress, causes coal body expansion and fracture development, becoming the core area for efficient gas desorption and enrichment. Efficient gas extraction from the decompression zone is a key link in preventing gas exceedances and improving extraction rates. Currently, gas extraction systems rely entirely on human experience for control. Gas extraction is currently the most effective method for preventing gas accidents. During the extraction process, the extraction negative pressure has a crucial impact on the gas extraction effect. Most mines in my country still use a fixed extraction negative pressure mode for gas extraction. Even though some mines use manual control to adjust the extraction negative pressure to improve the gas extraction effect, manual control often relies on human experience, resulting in inaccurate control and failing to dynamically adjust the negative pressure distribution in real time according to changes in stress ahead of the working face. With the development of automation technology, automated control technology is considered an important method to solve these problems. Especially since the depressurization zone in front of the working face is in a dynamic state of flux, the gas extraction system needs real-time sensing, intelligent analysis, and precise decision-making. It requires dynamic, adaptive, and optimized adjustments to key parameters such as extraction negative pressure and extraction flow rate to achieve efficient, economical, and safe gas extraction. Furthermore, automated gas extraction is a crucial construction task in the development of automated mines.

[0004] Therefore, there is an urgent need to construct a gas extraction control method based on the working face mining and depressurization area that integrates real-time perception, real-time decision-making, and precise execution to ensure safe coal mine production and improve resource utilization efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a method for controlling gas extraction in the mining-affected area in front of the working face, which solves the problems of gas extraction control relying entirely on human experience, inaccurate extraction control, low gas extraction efficiency, and safety risks in the prior art.

[0006] The technical solution adopted in this invention is a method for controlling gas extraction in the mining-affected area ahead of the working face, which is carried out according to the following steps: Step 1: Based on the field data, determine the dynamic range of the original stress zone, stress concentration zone and stress relief zone under normal mining speed conditions, and determine the variation law of the coal and rock stress field in front of the working face; Step 2: Establish a numerical model of the dynamic stress variation zone of the coal body in front of the working face, and determine the range of the stress variation zone in front of the working face. Step 3: Determine the layout scheme of the gas extraction and control area boreholes; Step 4: Gas extraction is carried out using a gas extraction control method based on the depressurization zone in front of the working face. Step 5: Determine the control scheme for the data transmission valve of gas extraction regulation.

[0007] The invention is further characterized by: The specific steps in step 1 are as follows: at least 100m ahead of the working face, drill a hole every 2-3m perpendicular to the coal face, with a drilling depth of not less than 40m. The hole is sealed using a two-plug-one-injection sealing process.

[0008] The specific steps in step 1 are as follows: measure the gas flow rate, gas concentration, and negative pressure in the extraction borehole once a day, plot the relationship between gas flow rate and working face distance, and determine the variation law of coal and rock stress field in front of the working face.

[0009] The specific steps in step 2 are as follows: based on theoretical and field measurement data, and taking the geological conditions of the coal seam and the coal mining technology of the longwall face as the basic parameters, establish a numerical model of the dynamic distribution range of the original stress zone, stress concentration zone and stress relief zone in front of the longwall face under normal mining speed conditions.

[0010] The specific steps in step 2 are as follows: collect the physical and mechanical parameters of the coal seam and surrounding rock, the geostress field, the coal permeability and porosity, use numerical simulation software to model the model, set the working face advance rate to simulate mining, and compare the range of stress change area in front of the working face during the theoretical mining period with the dynamic change range of the original stress zone, stress concentration zone and stress relief zone measured by field data in step 1. If the error range of each stress zone is less than 10%, then the dynamic change range of the original stress zone, stress concentration zone and stress relief zone measured by field data is determined as the range of stress change area in front of the working face.

[0011] Step 3 involves arranging groups of boreholes based on the dynamic change range of the original stress zone, stress concentration zone, pressure relief zone, and transition zone determined in Step 2. Each group consists of 2-5 gas extraction boreholes, and each group is equipped with a valve. There is at least one group of gas extraction boreholes in the pressure relief zone, one group of gas extraction boreholes in the transition zone between the pressure relief zone and the stress concentration zone, and one group of gas extraction boreholes in the transition zone between the stress concentration zone and the original stress zone.

[0012] Step 4 is as follows: If the ground data monitoring and control center detects that the gas extraction flow rate of the group of boreholes 8-17m in front of the working face decreases by more than 50% within 24 hours, then the extraction of the group of boreholes has entered the transition zone between the stress concentration zone and the original stress zone. The ground control center will automatically issue a command to adjust the opening of the valve of the group of boreholes and adjust the negative pressure to 13KPa. If the ground data monitoring and control center detects that the gas extraction flow rate of the group of boreholes at a distance of 3-10m in front of the working face increases by more than 50% within 24 hours, then the extraction of the group of boreholes has entered the transition zone between the stress concentration zone and the pressure relief zone. The ground control center issues an instruction to adjust the valve opening of the group of boreholes and adjust the negative pressure to not less than 20KPa. If the ground data monitoring and control center detects that the flow rate of the group of boreholes within 0-6m in front of the working face suddenly increases by more than 50% within 1 hour, then the group of boreholes is connected to the coal wall fissures. The valve is then closed to distribute the negative pressure to other boreholes.

[0013] Step 5 involves installing an intelligent control valve and a multi-parameter extraction monitoring instrument at the borehole opening and connecting them to the underground PLC control cabinet. The monitoring data is then transmitted to the ground control center. Based on the extraction monitoring data and the numerical model of the stress change area in front of the working face, it is determined that the borehole has entered the corresponding area of ​​the stress change area in front of the working face obtained in Step 2. The valve opening is adjusted for different areas to distribute the negative pressure of the borehole in the stress concentration area, the original stress area and the transition area between the stress concentration area and the stress concentration area to the pressure relief area and the transition area between the stress concentration area and the pressure relief area. The boreholes connected by coal wall fractures in the pressure relief area are closed.

[0014] The beneficial effects of this invention are: 1. This invention provides a method for intelligent gas extraction and control in the mining-affected area ahead of the working face. By considering the stress redistribution area formed ahead of the coal seam due to mining activities, and by determining the dynamic range of the original stress zone, stress concentration zone, and stress relief zone, combined with the intelligent gas extraction and control method, this method avoids the long-term "passive response" stage of gas extraction caused by the lack of dynamic parameter perception in the stress relief zone and insufficient intelligent decision-making capability of the extraction system. It achieves real-time matching of extraction parameters with gas emission patterns, and adaptive control with optimal global efficiency of the extraction system. 2. The present invention provides a method for intelligent gas extraction and control in the mining-affected area in front of the working face. It constructs a closed-loop control method that integrates real-time perception, intelligent decision-making, and precise execution. Through automation, it avoids the reliance on manual inspection and experience-based judgment for borehole negative pressure adjustment, which can lead to missed extraction windows due to response delays. This method is in line with the trend of coal mine automation construction and development.

[0015] 3. The present invention provides a method for intelligent gas extraction and control in the mining-affected area in front of the working face. By increasing the negative pressure of gas extraction in the depressurization zone, the gas extraction rate of the coal seam is increased, the amount of gas emitted during the mining process is reduced, and the safe and efficient production of the mine is ensured. Attached Figure Description

[0016] Figure 1 This is a flowchart of the gas extraction and control method for the mining-affected area in front of the working face of the present invention; Figure 2 This is a distribution diagram of the three zones and transition zone in front of the working face of the present invention.

[0017] In the diagram, 1 is the working face; 2 is the coal seam; 3 is the stress gradually recovering zone; 4 is the stress relief zone; 5 is the transition zone between the stress concentration zone and the stress relief zone; 6 is the stress concentration zone; 7 is the transition zone between the original stress zone and the stress concentration zone; and 8 is the original stress zone. Detailed Implementation

[0018] The following detailed description is provided in conjunction with specific implementation methods.

[0019] Example 1 like Figures 1-2 As shown, one side of the working surface 1 is the stress gradually recovering zone 3, and the other side of the working surface 1 is the stress relief zone 4. In front of the stress relief zone 4 are, in sequence, the transition zone between the stress concentration zone and the stress relief zone 5, the stress concentration zone 6, the transition zone between the original stress zone and the stress concentration zone 7, and the original stress zone 8.

[0020] The method for controlling gas drainage in the mining-affected area ahead of working face 1 includes the following steps: Step 1: Before adjustment, determine the dynamic variation range of the original stress zone 8, stress concentration zone 6, and stress relief zone 4 under normal mining speed conditions: The normal mining speed conditions here are affected by multiple factors such as mine output, coal seam 2 occurrence conditions, and the size of the longwall face 1. The daily mining speed varies from mine to mine, and this is common knowledge in the field of the art, and is determined based on actual working conditions.

[0021] The determination of the size of the original stress zone 8, stress concentration zone 6, and stress relief zone 4 is common knowledge in this field and will not be elaborated here. The size of these three zones needs to be determined comprehensively based on site conditions, such as burial depth, coal thickness, occurrence conditions, and mining methods.

[0022] First, in the first mining face 1 of the new mining area of ​​the mine, when the working face 1 is in the normal mining stage, the distribution range of the original stress zone 8, stress concentration zone 6 and stress relief zone 4 in front of the working face 1 during the mining period is measured on site. At least 100m in front of the advanced working face 1, a borehole is drilled every 3m perpendicular to the coal wall, with a borehole depth of not less than 50m and a borehole construction area of ​​not less than 100m. The borehole is sealed using a two-plug-one-injection sealing process.

[0023] Among these measures, the gas flow rate, gas concentration, and negative pressure of all extraction boreholes are measured once a day, and a curve showing the relationship between the gas flow rate of the extraction boreholes and the distance to working face 1 is plotted. Based on the extraction flow rate measured at different times, the stress state of the current coal body is determined.

[0024] The on-site measurement shows that the stress relief zone 4 is within 0-8m in front of the working face 1, the stress concentration zone 6 is within 8-15m in front of the working face 1, and the original stress zone 8 is located more than 15m in front of the working face 1.

[0025] The dynamic range of the stress field in front of working face 1 is determined by measuring the range of stress relief zone 4, stress concentration zone 6, and original stress zone 8 on site.

[0026] Step 2: Establish a numerical model of the dynamic stress variation zone of the coal body in front of working face 1: Based on theoretical and field measurement data, and taking the geological conditions and mining technology of coal seam 2 in working face 1 as the basic parameters, a numerical model of the dynamic distribution range of the original stress zone 8, stress concentration zone 6 and stress relief zone 4 in front of working face 1 under normal mining speed conditions is established.

[0027] Collect physical and mechanical parameters (density, elastic modulus, Poisson's ratio, compressive / tensile strength, cohesion, internal friction angle) of coal seam 2 and surrounding rock, geostress field (initial horizontal / vertical stress ratio, tectonic stress direction), coal permeability, and porosity.

[0028] The COMSOL numerical simulation software was used for geometric modeling. The advance rate of working face 1 was set to 3m per day for simulated mining. The stress evolution during the simulated advance process was verified to validate the measured data.

[0029] Comparing the measured data with the simulation results, the length error of each stress zone is within 10%. It can be determined that the stress relief zone 4 is within 0~5m in front of the working face 1, the transition zone 5 between the stress concentration zone and the stress relief zone is 5~9m in front of the working face 1, the stress concentration zone 6 is 9~13m in front of the working face 1, the transition zone 7 between the original stress zone and the stress concentration zone is 13~15m in front of the working face 1, and the original stress zone 8 is >15m in front of the working face 1.

[0030] Step 3: Determine the layout scheme of the gas intelligent extraction and control area boreholes: The on-site gas extraction radius was determined to be 2m. Based on the dynamic change range of the original stress zone 8, stress concentration zone 6, pressure relief zone 4, and transition zone determined in step 2, three gas extraction boreholes were grouped together, and a valve was installed in each group of boreholes. This ensured that there was at least one group of gas extraction boreholes in pressure relief zone 4, one group of gas extraction boreholes in transition zone 5 between stress concentration zone and pressure relief zone, and one group of gas extraction boreholes in transition zone 7 between original stress zone and stress concentration zone, enabling zoned extraction.

[0031] Step 4: Gas drainage control method based on the gas extraction and depressurization zone 4 ahead of working face 1: If the ground data monitoring and control center detects that the gas extraction flow rate of the borehole group within a distance of 13-15m in front of working face 1 decreases by more than 50% within 24 hours, it is determined that the borehole group has entered the transition zone 7 between the original stress zone and the stress concentration zone. The ground control center issues an instruction to automatically adjust the valve opening of the borehole group and adjust the negative pressure to 13KPa. If the ground data monitoring and control center detects that the gas extraction flow rate of the borehole group within a distance of 5-9m in front of working face 1 increases by more than 50% within 24 hours, it is determined that the borehole group has entered the transition zone 5 between the stress concentration zone and the pressure relief zone. The ground control center issues an instruction to automatically adjust the valve opening of the borehole group and adjust the negative pressure to 20KPa. If the ground data monitoring and control center detects that the flow rate of the group of boreholes in the pressure relief zone 4 within 0-5m in front of working face 1 suddenly increases by more than 50% within 1 hour, it is determined that the group of boreholes is connected to the coal wall fissures. The valves are then closed to distribute the negative pressure to other boreholes.

[0032] Step 5: Gas extraction and regulation data transmission valve control scheme: Three boreholes are drilled along the coal seam 2 in groups, each equipped with a CJZ4 series intelligent control valve and a QB30 series extraction multi-parameter monitoring instrument. The intelligent control valves and extraction multi-parameter monitoring instrument are connected to the underground PLC control cabinet, and the monitoring data is transmitted to the surface through the underground industrial ring network. Based on the extraction monitoring data and the numerical model of the stress change area in front of working face 1, the borehole is determined to be in the original stress zone 8, stress concentration zone 6, stress relief zone 4, transition zone 7 between the original stress zone and stress concentration zone, or transition zone 5 between the stress concentration zone and stress relief zone, according to the stress change range obtained in step 2. The valve opening is adjusted for different zones, with the minimum opening maintained at a negative pressure of 13 kPa. The negative pressure of the boreholes in the stress zone, the transition zone between the original stress zone 8 and the stress concentration zone 6 is distributed to the transition zone between the stress relief zone 4 and the stress concentration zone 6 and the stress relief zone 4, thereby increasing the extraction effect and efficiency. The boreholes connected to the coal wall fissures in pressure relief zone 4 were promptly closed, and the negative pressure of the extraction system was scientifically and rationally distributed by adjusting the opening and closing of valves and their degree of opening.

[0033] The reason for distributing the negative pressure of the boreholes located in stress concentration zone 6 and transition zone 7 (between the original stress zone and stress concentration zone) to stress relief zone 4 and transition zone 5 (between the stress concentration zone and stress relief zone) is as follows: Because stress concentration zone 6 and transition zone 7 (between the original stress zone and stress concentration zone) are affected by stress, the coal seam fissures are closed, making gas extraction very difficult. Even if the negative pressure is increased, it is difficult to extract the gas from coal seam 2. Therefore, the negative pressure is distributed to the extraction boreholes in stress relief zone 4 and transition zone 5 (between the stress concentration zone and stress relief zone). In this area, the fissures are opened due to stress, providing a gas flow channel. Therefore, increasing the negative pressure can improve the extraction effect.

[0034] Example 2 This embodiment proposes a method for intelligent gas extraction and control in the mining-affected area ahead of working face 1, such as... Figure 1 and Figure 2 As shown, it includes the following steps: Step 1: Determine the dynamic variation range of the original stress zone 8, stress concentration zone 6, and stress relief zone 4 under normal mining speed conditions based on field data.

[0035] A certain mine is a high-gas mine. The coal seam 2 is 4m thick, the working face 1 is buried at a depth of about 450m, the daily advance speed is 3m, and the gas content of coal seam 2 is 9m / t. 3 .

[0036] For the first mining face 1 in the mining area, 34 monitoring boreholes with a depth of 60m were arranged 100m in front of the working face 1, and the boreholes were sealed with two plugs and one injection. The boreholes were connected to the extraction system to monitor the daily flow rate changes of each borehole. Based on the daily monitoring data, the stress relief zone 4 was determined to be 0-6m, the stress concentration zone 6 to be 6-14m, and the original stress zone 8 to be >14m.

[0037] Step 2: Establish a numerical model of the dynamic stress change zone of the coal body in front of working face 1, and determine the range of the stress change zone in front of working face 1.

[0038] Basic data such as the occurrence parameters, mechanical parameters, original rock stress parameters, geological structure parameters, and mining history parameters of coal seam 2 were collected. Geometric modeling was performed using COMSOL numerical simulation software to simulate stress evolution during the advance process. The simulation results showed that the stress relief zone 4 was 0-7.5m, the stress concentration zone 6 was 7.5-13m, and the original stress zone 8 was >13m. The length error of each zone was within 10%, so the field measured data was considered reliable.

[0039] Step 3: Determine the layout scheme of the gas extraction and control area boreholes.

[0040] Based on the determined stress variation area in front of working face 1 and the drainage radius of the gas drainage borehole in coal seam 2, it is determined that one valve will be installed for every three boreholes.

[0041] Step 4: Gas extraction is carried out using the gas extraction control method based on the gas extraction and depressurization zone 4 in front of working face 1.

[0042] Monitoring revealed that the flow rate of a certain group of orifices located 13–15 m in front of working face 1 decreased by more than 50% within 24 hours (0.48 m). 3 / min decays to 0.19m 3 / min), automatically adjusting the valve to bring the negative pressure of this group of boreholes to 13kPa; the flow rate of a certain group of boreholes at 5–9m increased by more than 50% (0.21m) within 24 hours. 3 / min increased to 0.51m 3 The system automatically adjusts the valves to bring the negative pressure of this group of boreholes to 20 kPa (per minute); the system monitors that the flow rate of a certain group of boreholes within 0–5 m increased by more than 50% (0.68 m³ / min) within 1 hour. 3 / min increased to 1.22m 3 If the valve count is less than 1 / min, immediately close the valve group and use this as a standard for dynamic adjustment.

[0043] Step 5: Gas extraction and regulation data transmission valve control scheme: Three boreholes are drilled along the coal seam 2 in groups, each equipped with a CJZ4 series intelligent control valve and a QB30 series extraction multi-parameter monitoring instrument. The intelligent control valves and extraction multi-parameter monitoring instrument are connected to the underground PLC control cabinet, and the monitoring data is transmitted to the surface through the underground industrial ring network. Based on the extraction monitoring data and the numerical model of the stress change area in front of working face 1, the borehole is determined to be in the original stress zone 8, stress concentration zone 6, stress relief zone 4, transition zone 7 between the original stress zone and stress concentration zone, or transition zone 5 between the stress concentration zone and stress relief zone, according to the stress change range obtained in step 2. The valve opening is adjusted for different zones, with the minimum opening maintained at a negative pressure of 13 kPa. The negative pressure of the boreholes in the stress zone, the transition zone between the original stress zone 8 and the stress concentration zone 6 is distributed to the transition zone between the stress relief zone 4 and the stress concentration zone 6 and the stress relief zone 4, thereby increasing the extraction effect and efficiency. The boreholes connected to the coal wall fissures in pressure relief zone 4 were promptly closed, and the negative pressure of the extraction system was scientifically and rationally distributed by adjusting the opening and closing of valves and their degree of opening.

[0044] Example 3 This embodiment proposes a method for intelligent gas extraction and control in the mining-affected area ahead of working face 1, such as... Figure 1 and Figure 2 As shown, it includes the following steps: Step 1: Determine the dynamic variation range of the original stress zone 8, stress concentration zone 6, and stress relief zone 4 under normal mining speed conditions based on field data.

[0045] A certain mine is a coal and gas outburst mine. The coal seam 2 is 6m thick, the working face 1 is buried at a depth of about 800m, the daily advance speed is 2.5m, and the gas content of coal seam 2 is 13m³ / t. 3 .

[0046] For the first working face 1 of the mining area, boreholes were arranged at intervals of 2.5m and a depth of 70m within 100m in front of working face 1, and two plugs and one injection were used to seal the boreholes. The boreholes were connected to the extraction system, and the daily flow rate changes of each borehole were monitored. Based on the daily monitoring data, the stress relief zone 4 was determined to be 0–7m, the stress concentration zone to be 67–16m, and the original stress zone 8 to be >16m.

[0047] Step 2: Establish a numerical model of the dynamic stress change zone of the coal body in front of working face 1, and determine the range of the stress change zone in front of working face 1.

[0048] Basic data such as the occurrence parameters, mechanical parameters, original rock stress parameters, geological structure parameters, and mining history parameters of coal seam 2 were collected. The COMSOL numerical simulation software was used to perform geometric modeling and simulate the stress evolution during the advance. The simulation results showed that the stress relief zone 4 was 0–6m, the stress concentration zone 6 was 6–18m, and the original stress zone 8 was >18m. If the length error of each zone was within 10%, the field measured data was considered reliable.

[0049] Step 3: Determine the layout scheme of the gas extraction and control area boreholes.

[0050] Based on the determined stress variation area in front of working face 1 and the drainage radius of the gas drainage borehole in coal seam 2, it is determined that one valve will be installed for every 5 boreholes.

[0051] Step 4: Gas extraction is carried out using the gas extraction control method based on the gas extraction and depressurization zone 4 in front of working face 1.

[0052] Monitoring revealed that the flow rate of a certain group of orifices located 14–17m in front of working face 1 decreased by more than 50% (0.62m) within 24 hours. 3 / min decays to 0.28m 3 / min), automatically adjusting the valve to bring the negative pressure of this group of boreholes to 13kPa; the flow rate of a certain group of boreholes at 6-8m increased by more than 50% (0.33m) within 24 hours. 3 / min increased to 0.71m 3 The system automatically adjusts the valves to bring the negative pressure of this group of boreholes to 20 kPa (per minute); the system monitors that the flow rate of a certain group of boreholes within 0–5 m increased by more than 50% (0.69 m³ / min) within 1 hour. 3 / min increased to 1.21m 3 If the pressure is reduced to a certain value (e.g., / min), immediately close the valve group and dynamically adjust the negative pressure redistribution based on this standard.

[0053] Step 5: Gas extraction and regulation data transmission valve control scheme: Five boreholes are drilled along the coal seam 2, and each group is equipped with a CJZ4 series intelligent control valve and a QB30 series extraction multi-parameter monitoring instrument. The intelligent control valve and extraction multi-parameter monitoring instrument are connected to the underground PLC control cabinet, and the monitoring data is transmitted to the surface through the underground industrial ring network. Based on the extraction monitoring data and the numerical model of the stress change area in front of working face 1, the borehole is determined to be in the original stress zone 8, stress concentration zone 6, stress relief zone 4, transition zone 7 between the original stress zone and stress concentration zone, or transition zone 5 between the stress concentration zone and stress relief zone, according to the stress change range obtained in step 2. The valve opening is adjusted for different zones, with the minimum opening maintained at a negative pressure of 13 kPa. The negative pressure of the borehole in the stress zone, the transition zone between the original stress zone 8 and the stress concentration zone 6 is distributed to the transition zone between the stress relief zone 4 and the stress concentration zone 6 and the stress relief zone 4, thereby increasing the extraction effect and efficiency. The boreholes connected to the coal wall fissures in pressure relief zone 4 were promptly closed, and the negative pressure of the extraction system was scientifically and rationally distributed by adjusting the opening and closing of valves and their degree of opening.

[0054] Example 4 This embodiment proposes a method for intelligent gas extraction and control in the mining-affected area ahead of working face 1, such as... Figure 1 and Figure 2 As shown, it includes the following steps: Step 1: Determine the dynamic variation range of the original stress zone 8, stress concentration zone 6, and stress relief zone 4 under normal mining speed conditions based on field data.

[0055] A certain mine is a high-gas mine. The thickness of coal seam 2 is 1.2m, the working face 1 is buried at a depth of about 300m, the daily advance speed is 8m, and the gas content of coal seam 2 is 6m / t. 3 .

[0056] For the first working face 1 of the mining area, boreholes with a spacing of 2m and a depth of 40m are arranged within 100m in front of working face 1, and two plugs and one injection are used to seal the boreholes. The boreholes are connected to the extraction system, and the daily flow rate changes of each borehole are monitored. Based on the daily monitoring data, the pressure relief zone is determined to be 40–4m, the stress concentration zone is 64–10m, and the original stress zone is 8 > 10m.

[0057] Step 2: Establish a numerical model of the dynamic stress change zone of the coal body in front of working face 1, and determine the range of the stress change zone in front of working face 1.

[0058] Basic data such as the occurrence parameters, mechanical parameters, original rock stress parameters, geological structure parameters, and mining history parameters of coal seam 2 were collected. The COMSOL numerical simulation software was used to perform geometric modeling and simulate the stress evolution during the advance. The simulation results showed that the stress relief zone 4 was 0–5m, the stress concentration zone 6 was 5–9m, and the original stress zone 8 was >9m. If the length error of each zone was within 10%, the field measured data was considered reliable.

[0059] Step 3: Determine the layout scheme of the gas extraction and control area boreholes.

[0060] Based on the determined stress variation area in front of working face 1 and the drainage radius of the gas drainage borehole in coal seam 2, it is determined that one valve will be installed for every two boreholes.

[0061] Step 4: Gas extraction is carried out using the gas extraction control method based on the gas extraction and depressurization zone 4 in front of working face 1.

[0062] Monitoring revealed that the flow rate of a certain group of orifices located 8–11m in front of working face 1 decreased by more than 50% within 24 hours (0.38m). 3 / min decays to 0.12m 3 / min), automatically adjusting the valve to bring the negative pressure of this group of boreholes to 13kPa; the flow rate of a certain group of boreholes at 3-5m increased by more than 50% (0.16m) within 24 hours. 3 / min increased to 0.41m 3 The system automatically adjusts the valves to bring the negative pressure in this group of boreholes to 20 kPa (per minute); the system monitors that the flow rate in a certain group of boreholes within 0–2.5 m increased by more than 50% within 1 hour (0.51 m³ / min). 3 / min increased to 0.98m 3 If the pressure is reduced to a certain value (e.g., / min), immediately close the valve group and dynamically adjust the negative pressure redistribution based on this standard.

[0063] Step 5: Gas extraction and regulation data transmission valve control scheme: Two boreholes are drilled along the coal seam 2, and each group is equipped with a CJZ4 series intelligent control valve and a QB30 series extraction multi-parameter monitoring instrument. The intelligent control valve and extraction multi-parameter monitoring instrument are connected to the underground PLC control cabinet, and the monitoring data is transmitted to the surface through the underground industrial ring network. Based on the extraction monitoring data and the numerical model of the stress change area in front of working face 1, the borehole is determined to be in the original stress zone 8, stress concentration zone 6, stress relief zone 4, transition zone 7 between the original stress zone and stress concentration zone, or transition zone 5 between the stress concentration zone and stress relief zone, according to the stress change range obtained in step 2. The valve opening is adjusted for different zones, with the minimum opening maintained at a negative pressure of 13 kPa. The negative pressure of the borehole in the stress zone, the transition zone between the original stress zone 8 and the stress concentration zone 6 is distributed to the transition zone between the stress relief zone 4 and the stress concentration zone 6 and the stress relief zone 4, thereby increasing the extraction effect and efficiency. The boreholes connected to the coal wall fissures in pressure relief zone 4 were promptly closed, and the negative pressure of the extraction system was scientifically and rationally distributed by adjusting the opening and closing of valves and their degree of opening.

[0064] Example 5 This embodiment proposes a method for intelligent gas extraction and control in the mining-affected area ahead of working face 1, such as... Figure 1 and Figure 2 As shown, it includes the following steps: Step 1: Determine the dynamic variation range of the original stress zone 8, stress concentration zone 6, and stress relief zone 4 under normal mining speed conditions based on field data.

[0065] A certain mine is a high-gas mine. Working face 1 is an automated working face 1. The coal seam 2 is 8m thick. The working face 1 is buried at a depth of about 550m. The daily advance speed is 5m. The gas content of coal seam 2 is 3m / t. 3 .

[0066] For the first working face 1 of the mining area, boreholes with a spacing of 2m and a depth of 40m are arranged within 100m in front of working face 1, and two plugs and one injection are used to seal the boreholes. The boreholes are connected to the extraction system, and the daily flow rate changes of each borehole are monitored. Based on the daily monitoring data, the pressure relief zone is determined to be 40-5m, the stress concentration zone is 65-12m, and the original stress zone is 8>12m.

[0067] Step 2: Establish a numerical model of the dynamic stress change zone of the coal body in front of working face 1, and determine the range of the stress change zone in front of working face 1.

[0068] Basic data such as the occurrence parameters, mechanical parameters, original rock stress parameters, geological structure parameters, and mining history parameters of coal seam 2 were collected. The COMSOL numerical simulation software was used to perform geometric modeling and simulate the stress evolution during the advance. The simulation results showed that the stress relief zone 4 was 0–6m, the stress concentration zone 6 was 6–14m, and the original stress zone 8 was >14m. If the length error of each zone was within 10%, the field measured data was considered reliable.

[0069] Step 3: Determine the layout scheme of the gas extraction and control area boreholes.

[0070] Based on the determined stress variation area in front of working face 1 and the drainage radius of the gas drainage borehole in coal seam 2, it is determined that one valve will be installed for every four boreholes.

[0071] Step 4: Gas extraction is carried out using the gas extraction control method based on the gas extraction and depressurization zone 4 in front of working face 1.

[0072] Monitoring revealed that the flow rate of a certain group of orifices located 11–14m in front of working face 1 decreased by more than 50% within 24 hours (0.21m). 3 / min decays to 0.09m 3 / min), automatically adjusting the valve to bring the negative pressure of this group of boreholes to 13kPa; the flow rate of a certain group of boreholes at 5–7m increased by more than 50% (0.11m) within 24 hours. 3 / min increased to 0.24m 3 The system automatically adjusts the valves to bring the negative pressure of this group of boreholes to 26 kPa (per minute); the system monitors that the flow rate of a certain group of boreholes within 0–3 m increased by more than 50% within 1 hour (0.23 m³ / min). 3 / min increased to 0.42m 3 If the pressure is reduced to a certain value (e.g., / min), immediately close the valve group and dynamically adjust the negative pressure redistribution based on this standard.

[0073] Step 5: Gas extraction and regulation data transmission valve control scheme: Four boreholes are drilled along the coal seam 2, and each group is equipped with a CJZ4 series intelligent control valve and a QB30 series extraction multi-parameter monitoring instrument. The intelligent control valve and extraction multi-parameter monitoring instrument are connected to the underground PLC control cabinet, and the monitoring data is transmitted to the surface through the underground industrial ring network. Based on the extraction monitoring data and the numerical model of the stress change area in front of working face 1, the borehole is determined to be in the original stress zone 8, stress concentration zone 6, stress relief zone 4, transition zone 7 between the original stress zone and stress concentration zone, or transition zone 5 between the stress concentration zone and stress relief zone, according to the stress change range obtained in step 2. The valve opening is adjusted for different zones, with the minimum opening maintained at a negative pressure of 13 kPa. The negative pressure of the borehole in the stress zone, the transition zone between the original stress zone 8 and the stress concentration zone 6 is distributed to the transition zone between the stress relief zone 4 and the stress concentration zone 6 and the stress relief zone 4, thereby increasing the extraction effect and efficiency. The boreholes connected to the coal wall fissures in pressure relief zone 4 were promptly closed, and the negative pressure of the extraction system was scientifically and rationally distributed by adjusting the opening and closing of valves and their degree of opening.

[0074] Example 6 This embodiment proposes a method for intelligent gas extraction and control in the mining-affected area ahead of working face 1, such as... Figure 1 and Figure 2 As shown, it includes the following steps: Step 1: Determine the dynamic variation range of the original stress zone 8, stress concentration zone 6, and stress relief zone 4 under normal mining speed conditions based on field data.

[0075] A certain mine is a high-gas mine. Working face 1 is an automated working face 1. The coal seam 2 is 7m thick. The working face 1 is buried at a depth of about 555m. The daily advance speed is 5m. The gas content of coal seam 2 is 4m / t. 3 .

[0076] For the first working face 1 of the mining area, boreholes with a spacing of 2m and a depth of 40m are arranged within 100m in front of working face 1, and two plugs and one injection are used to seal the boreholes. The boreholes are connected to the extraction system, and the daily flow rate changes of each borehole are monitored. Based on the daily monitoring data, the pressure relief zone is determined to be 40-5m, the stress concentration zone is 65-10m, and the original stress zone is 8>10m.

[0077] Step 2: Establish a numerical model of the dynamic stress change zone of the coal body in front of working face 1, and determine the range of the stress change zone in front of working face 1.

[0078] Basic data such as the occurrence parameters, mechanical parameters, original rock stress parameters, geological structure parameters, and mining history parameters of coal seam 2 were collected. Geometric modeling was performed using COMSOL numerical simulation software to simulate stress evolution during the advance process. The simulation results showed that the stress relief zone 4 was 0–6m, the stress concentration zone 6 was 6–10m, and the original stress zone 8 was >11m. If the length error of each zone was within 10%, the field measured data was considered reliable.

[0079] Step 3: Determine the layout scheme of the gas extraction and control area boreholes.

[0080] Based on the determined stress variation area in front of working face 1 and the drainage radius of the gas drainage borehole in coal seam 2, it is determined that one valve will be installed for every four boreholes.

[0081] Step 4: Gas extraction is carried out using the gas extraction control method based on the gas extraction and depressurization zone 4 in front of working face 1.

[0082] Monitoring revealed that the flow rate of a certain group of orifices located 11–14m in front of working face 1 decreased by more than 50% within 24 hours (0.20m). 3 / min decays to 0.09m 3 / min), automatically adjusting the valve to bring the negative pressure of this group of boreholes to 13kPa; the flow rate of a certain group of boreholes at 6–10m increased by more than 50% (0.11m) within 24 hours. 3 / min increased to 0.24m 3 The system automatically adjusts the valves to bring the negative pressure of this borehole group to 26 kPa (per minute); the system monitors that the flow rate of a certain group of boreholes within 0–4 m increased by more than 50% within 1 hour (0.23 m³ / min). 3 / min increased to 0.42m 3 If the pressure is reduced to a certain value (e.g., / min), immediately close the valve group and dynamically adjust the negative pressure redistribution based on this standard.

[0083] Step 5: Gas extraction and regulation data transmission valve control scheme: Four boreholes are drilled along the coal seam 2, and each group is equipped with a CJZ4 series intelligent control valve and a QB30 series extraction multi-parameter monitoring instrument. The intelligent control valve and extraction multi-parameter monitoring instrument are connected to the underground PLC control cabinet, and the monitoring data is transmitted to the surface through the underground industrial ring network. Based on the extraction monitoring data and the numerical model of the stress change area in front of working face 1, the borehole is determined to be in the original stress zone 8, stress concentration zone 6, stress relief zone 4, transition zone 7 between the original stress zone and stress concentration zone, or transition zone 5 between the stress concentration zone and stress relief zone, according to the stress change range obtained in step 2. The valve opening is adjusted for different zones, with the minimum opening maintained at a negative pressure of 13 kPa. The negative pressure of the borehole in the stress zone, the transition zone between the original stress zone 8 and the stress concentration zone 6 is distributed to the transition zone between the stress relief zone 4 and the stress concentration zone 6 and the stress relief zone 4, thereby increasing the extraction effect and efficiency. The boreholes connected to the coal wall fissures in pressure relief zone 4 were promptly closed, and the negative pressure of the extraction system was scientifically and rationally distributed by adjusting the opening and closing of valves and their degree of opening.

[0084] All aspects not detailed herein are well-known to those skilled in the art. Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of this invention and not intended to limit it. Although the invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this invention without departing from the spirit and scope of the invention, and all such modifications and substitutions should be covered within the scope of the claims of this invention.

Claims

1. A method for controlling gas extraction in the mining-affected area ahead of the working face, characterized in that, Follow these steps: Step 1: Based on the field data, determine the dynamic range of the original stress zone (8), stress concentration zone (6) and stress relief zone (4) under normal mining speed conditions, and determine the change law of the coal and rock stress field in front of the working face (1); Step 2: Use numerical simulation software to establish a numerical model of the dynamic stress change zone of the coal body in front of the working face (1) and determine the range of the stress change zone in front of the working face (1). Step 3: Determine the layout scheme of the gas extraction and control area boreholes; Step 4: Gas extraction is carried out using the gas extraction control method based on the depressurization zone (4) in front of the working face (1); Step 5: Determine the control scheme for the data transmission valve of gas extraction regulation; The specific steps in step 2 are as follows: collect the physical and mechanical parameters of the coal seam and surrounding rock, the geostress field, the coal permeability and porosity, use numerical simulation software to model, set the advance rate of the working face (1) to simulate mining, determine the range of stress change area in front of the working face (1) during theoretical mining and compare it with the dynamic change range of the original stress area (8), stress concentration area (6) and stress relief area (4) measured by field data in step 1. If the error range of each stress area is less than 10%, then the dynamic change range of the original stress area (8), stress concentration area (6) and stress relief area (4) measured by field data is determined as the range of stress change area in front of the working face (1). The specific steps of step 3 are as follows: combining the original stress zone (8), stress concentration zone (6) and pressure relief zone (4) determined in step 2, and the dynamic change range of the transition zone, arrange the groups of holes. Every 2-5 gas extraction holes form a group and each group of holes is equipped with a valve. There is at least one group of gas extraction holes in the pressure relief zone (4), one group of gas extraction holes in the transition zone (5) between the stress concentration zone and the pressure relief zone, and one group of gas extraction holes in the transition zone (7) between the original stress zone and the stress concentration zone. The specific steps of step 4 are as follows: the ground data monitoring and control center monitors that the gas extraction flow rate of the group of boreholes 8-17m in front of the working face (1) decreases by more than 50% within 24 hours. Then the extraction of the group of boreholes enters the transition zone (7) between the original stress zone and the stress concentration zone. The ground control center issues an instruction to adjust the opening of the valve of the group of boreholes and adjust the negative pressure to 13KPa. If the ground data monitoring and control center detects that the gas extraction flow rate of the group of boreholes 3-10m in front of the working face (1) increases by more than 50% within 24 hours, then the extraction of the group of boreholes will enter the transition zone between the stress concentration zone and the pressure relief zone (5). The ground control center will issue an instruction to adjust the valve opening of the group of boreholes and adjust the negative pressure to not less than 20KPa. If the ground data monitoring and control center detects that the flow rate of the group of boreholes within 0-6m in front of the working face (1) suddenly increases by more than 50% within 1 hour, then the group of boreholes is connected to the coal wall fissures. The valve is closed to distribute the negative pressure to other boreholes.

2. The gas extraction and control method for the mining-affected area ahead of the working face according to claim 1, characterized in that, The specific steps in step 1 are as follows: at a distance of not less than 100m in front of the advanced working face (1), a borehole is drilled every 2-3m perpendicular to the coal wall. The depth of the borehole is not less than 40m. The borehole is sealed using a two-plug-one-injection sealing process.

3. The gas extraction and control method for the mining-affected area ahead of the working face according to claim 2, characterized in that, The specific steps in step 1 are as follows: measure the gas flow rate, gas concentration and negative pressure of the borehole once a day, draw a curve showing the relationship between the extraction time and the distance to the working face (1), and determine the change law of the coal and rock stress field in front of the working face (1).

4. The gas extraction and control method for the mining-affected area ahead of the working face according to claim 1, characterized in that, The specific steps in step 2 are as follows: based on theoretical and field measurement data, and taking the geological conditions of the coal seam and the coal mining technology of the longwall face (1) as the basic parameters, establish a numerical model of the dynamic distribution range of the original stress zone (8), stress concentration zone (6) and stress relief zone (4) in front of the longwall face under normal longwall mining speed conditions.

5. The gas extraction and control method for the mining-affected area ahead of the working face according to claim 1, characterized in that, The specific steps of step 5 are as follows: install intelligent control valve and extraction multi-parameter monitoring instrument at the extraction end of the borehole and connect them to the underground PLC control cabinet, and then transmit the monitoring data to the ground control center; based on the extraction monitoring data and the numerical model of the stress change area in front of the working face (1), determine that the borehole has entered the corresponding area of ​​the stress change area in front of the working face (1) obtained in step 2, adjust the valve opening for different areas, and distribute the negative pressure of the borehole in the stress concentration area (6), the transition area between the original stress area and the stress concentration area (7) to the pressure relief area (4) and the transition area between the stress concentration area and the pressure relief area (5), and close the boreholes that are connected by coal wall cracks in the pressure relief area (4).

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