Coal seam gas extraction drilling hole surrounding fissure continuous sealing device and sealing method thereof

Abstract

This invention relates to the field of mine gas control technology, specifically disclosing a continuous sealing device and method for fractures around coal seam gas drainage boreholes. It includes a sealing component and a grouting component installed in the drainage borehole within the coal seam, as well as a monitoring component and a control unit. The grouting component delivers gel-like sealing material; the monitoring component collects real-time data on gas pressure, concentration, flow rate, and grouting parameters; the control unit incorporates an adaptive multi-field coupled grouting optimization algorithm to intelligently generate grouting commands. Through closed-loop control, it precisely executes initial sealing and dynamic continuous sealing. This invention achieves intelligent and adaptive sealing of the borehole fracture network, significantly improving gas drainage efficiency and borehole sealing reliability, and ensuring safe mine production.

Description

Technical Field

[0001] This invention relates to the field of mine gas control technology, specifically to a continuous sealing device and method for cracks around coal seam gas drainage boreholes, applicable to gas drainage and sealing operations in high-gas coal seams. Background Technology

[0002] In underground gas drainage projects in coal mines, the superimposed stress concentration effect generated by coal roadway construction and in-seam drilling causes damage and deterioration of the coal body around the borehole, leading to the formation of macroscopic and microscopic fractures of different shapes in the coal roadway and around the borehole. These fractures interconnect to form a fracture network, which further develops during mining disturbances and drainage processes, resulting in an increase in the number and aperture of fractures. This provides a seepage channel for ventilation air from the coal roadway to enter the drainage borehole. The large influx of air into the borehole causes a sharp drop in the concentration and purity of the extracted gas, which not only significantly reduces the gas drainage efficiency but also results in the ineffective consumption of drainage power and shortens the effective service life of the borehole.

[0003] Conventional sealing materials suffer from problems such as shrinkage cracking and insufficient permeability, making it difficult to effectively penetrate the fracture network around the borehole. Furthermore, after curing, they lack flexibility and adaptability, failing to cope with the dynamic expansion of fractures caused by mining disturbances. Simultaneously, traditional sealing processes have low automation levels, making it difficult to achieve real-time control based on gas concentration fluctuations, thus hindering the improvement of gas extraction efficiency. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a continuous sealing device and method for fractures around coal seam gas drainage boreholes. Through dynamic control algorithms and intelligent hardware integration, it achieves efficient sealing of fracture networks and improves gas drainage efficiency.

[0005] This invention is achieved through the following technical solution:

[0006] A continuous sealing device for fractures around a coal seam gas borehole includes a sealing component and a grouting component installed in a drainage borehole opened in the coal seam, and also includes a monitoring component and a control unit.

[0007] The sealing assembly consists of two sets, forming an independent grouting sealing space within the extraction borehole as a sealing section. The sealing assembly includes multiple baffles and filling material located between the baffles.

[0008] The grouting assembly includes a grouting pipe, a return grouting pipe, a grouting pump, a grouting valve, a check valve, a return grouting flow meter, and a grouting storage tank. The inlets of both the grouting pipe and the return grouting pipe are located within the sealing section, and the extension length of the grouting pipe within the sealing section is greater than the extension length of the return grouting pipe. A return grouting flow meter is installed inside the return grouting pipe to monitor the return grouting volume and determine when to stop grouting. One end of the grouting pump is connected to the grouting pipe to pump gel-like sealing material into the sealing section, and the other end is connected to the grouting storage tank, which stores the gel-like sealing material. The grouting pump is signal-connected to the monitoring assembly and control unit and is controlled to start when preset grouting conditions are met. The grouting valve is located on the pipeline between the grouting pipe and the grouting pump to control the on / off state of grouting. A check valve is installed at the end of the return grouting pipe.

[0009] The gas extraction pipe passes through the sealing assembly and the sealing section;

[0010] The monitoring component is used to collect key physical parameters during the grouting and sealing process in real time and feed the data back to the control unit. The monitoring component includes a gas sensor, a slurry sensor, and a signal transmission line. The gas sensor is located inside the gas extraction pipe and integrates a gas concentration sensor, a gas flow sensor, and a gas pressure sensor. The slurry sensor is located inside the grouting pipe and integrates a slurry flow sensor and a slurry pressure sensor. The gas sensor and the slurry sensor establish a communication connection with the control unit via the signal transmission line, uploading the monitored sensor data in real time to provide data basis for the control unit to determine grouting conditions and automatically start and stop the grouting pump.

[0011] The control unit includes a data processor, a PLC controller, and a mobile device. The data processor communicates with the monitoring components via a signal transmission line, receiving real-time monitoring data from the gas sensor and slurry sensor. The processor has a built-in signal conditioning circuit and analog-to-digital converter module, capable of converting received analog signals into digital signals and performing data filtering preprocessing before transmitting the processed standard digital signal to the PLC controller. The PLC controller receives multi-physics data in real time, performs coupled analysis and intelligent decision-making to determine the optimal timing for grouting start and stop. The PLC controller is connected to the mobile device, which is used for data and algorithm visualization, enabling real-time monitoring of grouting and extraction status.

[0012] The specific steps of the continuous sealing method for coal seam gas drainage boreholes are as follows:

[0013] S1: Layout and setting of sealing parameters. First, prepare gel-state sealing material. Add water to the sealing material in small amounts multiple times while stirring evenly to ensure thorough mixing of all components and stable material texture. Inject the material into the grouting assembly's storage tank. Then connect the storage tank to the grouting pump, followed by connecting the grouting pipe to the pump to complete the layout process. Simultaneously, set the gas extraction concentration threshold C0, gas flow rate threshold Q0, gas pressure threshold P0, and minimum gas concentration C using mobile equipment. L Minimum grouting pressure P L And send it to the PLC controller for storage.

[0014] S2: Data acquisition and processing. This involves real-time monitoring and acquisition of gas pressure P, gas concentration C, and gas flow rate Q within the gas extraction borehole using gas sensors, as well as the grouting pressure P during the grouting process. j and grouting volume Q j The collected data is converted and transmitted to the control unit; the control unit's data processor preprocesses the multi-source data, eliminating the order-of-magnitude differences between gas pressure P, gas concentration C, and gas flow rate Q, and calculates the comprehensive index S(t):

[0015]

[0016] In the formula, S(t) is the comprehensive sealing status index at time t, P(t) is the gas pressure after treatment at time t, C(t) is the gas concentration after treatment at time t, Q(t) is the gas flow rate after treatment at time t, α, β, and γ are weighting coefficients, and α+β+γ=1.

[0017] S3: Initial sealing: The sealing baffle is sent into the sealing section of the extraction borehole. The grouting pump is started, and gel-like sealing material is injected into the sealing section through the grouting pipe. The grouting pressure is controlled, and the return flow meter is used to monitor the return flow. When the sealing material overflows from the return pipe, the grouting is stopped, and the basic sealing structure is formed.

[0018] S4: Dynamic continuous sealing. After a sealing structure is formed, the gas sensor and slurry sensor transmit data to the control unit in real time. The data processor monitors the data in real time and performs data processing in step S2. Based on the pre-processed monitoring data, the PLC controller determines whether the dynamic grouting start-up conditions are met.

[0019] ① Early warning stage: Grouting pressure P collected by the grout sensor j Not lower than the set minimum grouting pressure P L If the gas concentration C collected by the gas sensor is lower than the set concentration threshold C0 and the gas flow rate Q is lower than the set flow rate threshold Q0, the grouting warning is activated, and grouting is prepared.

[0020] ② Grouting start-up stage: When grouting is started, at the instant of start-up, due to the pressure relief gas concentration C and the grouting flow rate Q j The concentration changes at the rate of change (ΔC(t) after treatment) with the time increment (Δt) reaches -0.4. Simultaneously, the ratio of the change in grouting flow rate (ΔQ(t) after treatment) to the time increment (Δt) also reaches -0.4. The PLC controller generates a grouting command. If the ratio is less than -0.4, it indicates rapid crack expansion, requiring an emergency grouting command. The grouting command controls the opening of the grouting valve and the start of the grouting pump via a signal transmission line, initiating dynamic grouting. Upon initiation, the rates of change in concentration and flow rate fluctuate between -0.1 and -0.4, with the slope gradually decreasing.

[0021] ③ Stable grouting stage: After grouting for a period of time, the gas concentration and flow rate show an upward trend, and the rate of change of concentration and flow rate fluctuates between 0.1 and 0.4. When the rate of change of concentration and flow rate exceeds the set range, the PLC controller sends an adjustment grouting command to the grouting pump to reduce the amount of grout injected into the sealing section; when it is below the set range, the amount of grout injected into the sealing section is increased.

[0022] ④ Grouting stop stage: After the gas pressure sensor value stabilizes, when the gas concentration C reaches the set concentration threshold C0 and the gas flow rate Q reaches the set flow rate threshold Q0, or when the concentration change rate and flow rate change rate are greater than 0.5, the PLC controller generates a grouting termination command, controls the grouting pump to stop, and closes the grouting valve to complete the dynamic continuous sealing process.

[0023] S5: Gas extraction. After dynamic continuous sealing is completed, the downhole gas pipeline is connected to the gas extraction pipeline via a flange for extraction operation. During gas extraction, the gas pressure sensor, gas flow sensor, and gas concentration sensor transmit data to the PLC controller in real time and transmit the data to the mobile device, which monitors the grouting and extraction status in real time. During extraction, the PLC controller monitors the gas concentration C in real time. When the gas extraction concentration falls below the set minimum gas concentration C... L When the gas extraction stops, the PLC controller sends a stop command and automatically executes step S4. This process is repeated to achieve continuous grouting and efficient gas extraction.

[0024] This invention provides a continuous sealing device and method for cracks around coal seam gas drainage boreholes, with the following advantages:

[0025] This device employs a dual-grouting dynamic sealing method, significantly improving borehole sealing reliability. Through a phased sealing process involving initial grouting and dynamic continuous grouting, it achieves multi-stage sealing within the borehole. The initial grouting forms structural support, while the dynamic continuous grouting utilizes gel-like sealing materials to penetrate the fracture network.

[0026] The device achieves intelligent monitoring and adaptive control, integrates multi-source sensors for gas concentration, flow rate, and pressure, constructs a multi-parameter, multi-threshold linkage model, analyzes data in real time and dynamically generates grouting instructions, and realizes automated closed-loop management of the entire process of "monitoring-control-sealing".

[0027] This device significantly improves the sealing performance, gas extraction concentration, and extraction efficiency of gas extraction boreholes, promotes the resource utilization of gas, and has wide applicability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0029] Figure 2 This is a logic flowchart of the method of the present invention;

[0030] Figure 1 mark:

[0031] 1-Grouting pump; 2-Data processor; 3-Gas sensor; 4-Slurry sensor; 5-Slurry flow sensor; 6-Slurry pressure sensor; 7-Gas concentration sensor; 8-Gas flow sensor; 9-Gas pressure sensor; 10-Baffle; 11-Grouting pipe; 12-Return slurry pipe; 13-One-way valve; 14-Sealing section, which is the annular area between two sealing baffles; 15-Gas extraction pipe; 16-Coal seam; 17-Signal transmission line; 18-Extraction borehole; 19-Grouting valve; 20-PLC controller; 21-Mobile equipment; 22-Return slurry flow meter; 23-Slurry storage tank. Detailed Implementation

[0032] Combination Figures 1 to 2 As shown, this invention provides a specific implementation method for continuously sealing fractures around coal seam gas extraction.

[0033] like Figure 1 As shown, a continuous sealing device for fractures around a coal seam gas borehole includes a sealing component and a grouting component in an extraction borehole 18 opened in the coal seam 16, and also includes a monitoring component and a control unit.

[0034] The sealing assembly is mainly used to construct an independent grouting and sealing space within the extraction borehole 18 as a sealing section 14. This assembly includes multiple baffles 10 and filling material located between the baffles 10. Preferably, two sets of sealing assemblies are sequentially arranged within the extraction borehole 18 from the borehole opening to the bottom: the first set of sealing assemblies is fixedly installed at the front of the extraction borehole 18, near the borehole opening, and the second set of sealing assemblies is fixedly installed at the end of the sealing section 14, at a predetermined depth away from the borehole opening. Each set of sealing assemblies, with its baffles 10, defines an annular closed isolation zone within the extraction borehole 18. This isolation zone is filled with cement mortar, which, after curing, forms a high-strength, highly sealing filler. The baffles 10 and the cement mortar filler work together to achieve efficient sealing and reliable isolation at both ends of the sealing section 14, providing a stable pressure environment for subsequent grouting operations.

[0035] like Figure 1 As shown, the grouting assembly includes a grouting pipe 11, a return grouting pipe 12, a grouting pump 1, a grouting valve 19, a one-way valve 13, a return grouting flow meter 22, and a grouting storage tank 23. The inlets of both the grouting pipe 11 and the return grouting pipe 12 are located within the sealing section 14, and the extension length of the grouting pipe 11 within the sealing section 14 is greater than the extension length of the return grouting pipe 12. A return grouting flow meter 22 is installed inside the return grouting pipe 12 to monitor the return grouting volume and determine when to stop grouting. One end of the grouting pump 1 is connected to the grouting pipe 11 to pump gel-like sealing material into the sealing section 14, and the other end is connected to the grouting storage tank 23, which stores the gel-like sealing material. The grouting pump 1 is signal-connected to the monitoring assembly and control unit and is controlled to start when preset grouting conditions are met. The grouting valve 19 is located on the pipeline between the grouting pipe 11 and the grouting pump 1 to control the on / off state of grouting. The end of the return slurry pipe 12 is equipped with a one-way valve 13 to prevent slurry backflow.

[0036] Gas extraction pipe 15 passes through sealing assembly and sealing section 14;

[0037] The monitoring component is used to collect key physical parameters during the grouting and sealing process in real time and feed the data back to the control unit. This monitoring component mainly includes a gas sensor 3, a slurry sensor 4, and a signal transmission line. The gas sensor 3, as an integrated sensing unit, is located inside the gas extraction pipe 15. It integrates: a gas concentration sensor 7 for detecting the gas concentration in the extraction pipe; a gas flow sensor 8 for detecting the instantaneous and cumulative flow of gas; and a gas pressure sensor 9 for detecting the gas pressure status in the pipe. The slurry sensor 4, as an integrated sensing unit, is located inside the grouting pipe 11. It integrates: a slurry flow sensor 5 for detecting the real-time injection flow of the gel-like sealing material; and a slurry pressure sensor 6 for detecting pressure changes in the grouting pipe. The gas sensor 3 and the slurry sensor 4 establish a communication connection with the control unit via the signal transmission line 17, thereby uploading the monitored sensor data in real time and providing data basis for the control unit to determine grouting conditions and automatically start and stop the grouting pump 1.

[0038] The control unit includes a data processor 2, a PLC controller 20, and a mobile device 21. The data processor 2 is communicatively connected to the monitoring components via a signal transmission line, and is used to receive real-time monitoring data from the gas sensor 3 and the slurry sensor 4. The processor 2 has a built-in signal conditioning circuit and an analog-to-digital converter module, which can convert the received analog signals into digital signals and perform preprocessing such as data filtering and compensation before transmitting the processed standard digital signals to the PLC controller 20. The PLC controller 20 internally stores and runs an adaptive multi-field coupled grouting optimization algorithm. This algorithm performs coupled analysis and intelligent decision-making based on real-time received multi-physical field data such as gas pressure, gas concentration, slurry pressure, and slurry flow rate to accurately determine the optimal timing for grouting start and stop. The PLC controller 20 is connected to the mobile device 21, which is used for data and algorithm visualization, enabling real-time monitoring of grouting and extraction status.

[0039] like Figure 2 The working method of the above-mentioned continuous sealing device for coal seam gas drainage boreholes includes the following specific steps:

[0040] S1: Layout and setting of sealing parameters. First, prepare gel-state sealing material. Add water to the sealing material in small amounts multiple times while stirring evenly to ensure thorough mixing of all components and stable material texture. Inject the material into the grout storage tank 23 of the grouting assembly. Then connect the grout storage tank 23 to the grouting pump 1, followed by connecting the grouting pipe 11 to the grouting pump 1 to complete the layout process. Simultaneously, set the gas extraction concentration threshold C0, gas flow rate threshold Q0, gas pressure threshold P0, and minimum gas concentration C using the mobile device 21. L Minimum grouting pressure P LAnd send it to the PLC controller 20 for storage.

[0041] S2: Data acquisition and processing. Gas pressure P, gas concentration C, and gas flow rate Q within the gas extraction borehole 18 are monitored and acquired in real time via gas sensor 3, as well as the grouting pressure P during the grouting process. j and grouting volume Q j The collected data is converted and transmitted to the control unit; the data processor 2 of the control unit preprocesses the multi-source data to eliminate the order-of-magnitude differences between gas pressure P, gas concentration C, and gas flow rate Q, and calculates the comprehensive index S(t):

[0042]

[0043] In the formula, S(t) is the comprehensive sealing status index at time t, P(t) is the gas pressure after treatment at time t, C(t) is the gas concentration after treatment at time t, Q(t) is the gas flow rate after treatment at time t, α, β, and γ are weighting coefficients, and α+β+γ=1.

[0044] S3: Initial sealing: The sealing baffle 10 is sent into the sealing section 14 in the extraction borehole 18, the grouting pump 1 is started, and gel-like sealing material is injected into the sealing section 14 through the grouting pipe 11. The grouting pressure is controlled, and the return flow meter 22 is used to monitor the return flow. When the sealing material overflows from the return pipe 12, the grouting is stopped, and the basic sealing structure is formed.

[0045] S4: Dynamic continuous sealing. After the sealing structure is formed, the gas sensor 3 and the slurry sensor 4 transmit data to the control unit in real time. The data processor monitors the data in real time and performs data processing in step S2. Based on the pre-processed monitoring data, the PLC controller 20 determines whether the dynamic grouting start-up conditions are met.

[0046] ① Early warning stage: Grouting pressure P collected by grout sensor 4 j Not lower than the set minimum grouting pressure P L If the gas concentration C collected by gas sensor 3 is lower than the set concentration threshold C0 and the gas flow rate Q is lower than the set flow rate threshold Q0, the grouting warning is activated, and grouting is prepared.

[0047] ② Grouting start-up stage: When grouting is started, at the instant of start-up, due to the pressure relief gas concentration C and the grouting flow rate Q jThe concentration changes at the rate of change (ΔC(t) after treatment) with the ratio of the change in gas concentration (C(t)) to the time increment (Δt), i.e., the rate of change in concentration, reach -0.4. Simultaneously, the ratio of the change in grouting flow rate (Q(t) after treatment) to the time increment (Δt), i.e., the rate of change in flow rate, also reaches -0.4. The PLC controller 20 generates a grouting command. If the ratio is less than -0.4, it indicates rapid crack expansion, requiring an emergency grouting command to be triggered. The grouting command controls the opening of the grouting valve 19 and the start of the grouting pump 1 via the signal transmission line 17, initiating dynamic grouting. Upon initiation of grouting, the rates of change in concentration and flow rate fluctuate between -0.1 and -0.4, with the slope gradually decreasing.

[0048] ③ Stable grouting stage: After grouting for a period of time, the gas concentration and flow rate show an upward trend, and the rate of change of concentration and flow rate fluctuates between 0.1 and 0.4. When the rate of change of concentration and flow rate exceeds the set range, the PLC controller 20 sends an adjustment grouting command to the grouting pump 1 to reduce the amount of grout injected into the sealing section 14; when it is lower than the set range, the amount of grout injected into the sealing section 14 is increased.

[0049] ④ Grouting stop stage: After the gas pressure sensor value stabilizes, when the gas concentration C reaches the set concentration threshold C0 and the gas flow rate Q reaches the set flow rate threshold Q0 or the concentration change rate and flow rate change rate are greater than 0.5, the PLC controller 20 generates a grouting termination command, controls the grouting pump 1 to stop, and closes the grouting valve 19 to complete the dynamic continuous sealing process.

[0050] S5: Gas extraction. After dynamic continuous sealing is completed, the downhole gas pipeline is connected to the gas extraction pipe 15 via a flange for extraction operation. During gas extraction, the gas pressure sensor 9, gas flow sensor 8, and gas concentration sensor 7 transmit data to the PLC controller 20 in real time and transmit the data to the mobile device 21. The mobile device 21 monitors the grouting and extraction status in real time. During the extraction process, the PLC controller 20 monitors the gas concentration C in real time. When the gas extraction concentration is lower than the set minimum gas concentration C... L When the gas extraction stops, the PLC controller 20 sends a stop command and automatically executes step S4. This process is repeated to achieve continuous grouting and efficient gas extraction.

Claims

1. A continuous sealing device for fractures around coal seam gas boreholes, characterized in that, It includes a sealing assembly and a grouting assembly in the extraction borehole (18) opened in the coal seam (16), as well as a monitoring assembly and a control unit; The sealing assembly consists of two sets, with an independent grouting sealing space constructed within the extraction borehole (18) as the sealing section (14). The grouting assembly includes a grouting pipe (11), a return grouting pipe (12), a grouting pump (1), a grouting valve (19), a check valve (13), a return grouting flow meter (22), and a grouting tank (23). The openings of the grouting pipe (11) and the return grouting pipe (12) are both located within the sealing section (14), and the extension length of the grouting pipe (11) within the sealing section (14) is greater than the extension length of the return grouting pipe (12). The return grouting pipe (12) is equipped with a return grouting flow meter (22) inside, which is used to monitor the amount of return grout and determine when to stop grouting. The grouting pump (1) is connected to the grouting pipe (11) at one end for pumping gel-like sealing material into the sealing section (14), and to the grout storage tank (23) at the other end for storing gel-like sealing material. The grouting pump (1) is connected to the monitoring component and control unit for signal connection and is controlled to start when the preset grouting conditions are met. The grouting valve (19) is located on the pipeline between the grouting pipe (11) and the grouting pump (1) for controlling the grouting flow. The end of the return grout pipe (12) is provided with a one-way valve (13). The gas extraction pipe (15) passes through the sealing assembly and the sealing section (14). The monitoring component is used to collect key physical parameters during the grouting and sealing process in real time and feed the data back to the control unit.

2. The continuous sealing device for fractures around coal seam gas boreholes according to claim 1, characterized in that, The sealing assembly includes multiple baffles (10) and a filling material located between the baffles (10).

3. The continuous sealing device for fractures around coal seam gas boreholes according to claim 1, characterized in that, The monitoring components include a gas sensor (3), a slurry sensor (4), and a signal transmission line. The gas sensor (3) is arranged inside the gas extraction pipe (15) and integrates a gas concentration sensor (7), a gas flow sensor (8), and a gas pressure sensor (9). The slurry sensor (4) is arranged inside the grouting pipe (11) and integrates a slurry flow sensor (5) and a slurry pressure sensor (6). The gas sensor (3) and the slurry sensor (4) establish a communication connection with the control unit through the signal transmission line (17) and upload the monitored sensor data in real time to provide data basis for the control unit to judge the grouting conditions and automatically start and stop the grouting pump (1).

4. The continuous sealing device for fractures around coal seam gas boreholes according to claim 3, characterized in that, The control unit includes a data processor (2), a PLC controller (20), and a mobile device (21). The data processor (2) is connected to the monitoring components via a signal transmission line to receive real-time monitoring data from the gas sensor (3) and the slurry sensor (4). The processor (2) has a built-in signal conditioning circuit and an analog-to-digital conversion module, which can convert the received analog signal into a digital signal and perform data filtering preprocessing. Then, the processed standard digital signal is transmitted to the PLC controller (20). The PLC controller (20) receives multi-physics field data in real time, performs coupling analysis and intelligent decision-making, and determines the best time to start and stop grouting. The PLC controller (20) is connected to the mobile device (21), which is used for data and algorithm visualization to realize real-time monitoring of grouting and extraction status.

5. A continuous sealing device for fractures around coal seam gas boreholes, characterized in that, The method using the continuous sealing device for fractures around coal seam gas boreholes according to any one of claims 1 to 4, specifically comprises the following steps: S1: Setting up and configuring the sealing parameters. First, prepare the gel-state sealing material. Add water to the sealing material in small amounts and stir evenly to ensure that the components are fully mixed and the material is stable. Then, inject the material into the grout storage tank (23) of the grouting assembly. Then, connect the grout storage tank (23) to the grouting pump (1) and then connect the grouting pipe (11) to the grouting pump (1) to complete the setup process. At the same time, set the gas extraction concentration threshold C0, gas flow threshold Q0, gas pressure threshold P0, and minimum gas concentration C using the mobile device (21). L Minimum grouting pressure P L And send it to the PLC controller (20) for storage; S2: Data acquisition and processing. The gas pressure P, gas concentration C and gas flow rate Q in the gas extraction borehole (18) are monitored and collected in real time by the gas sensor (3), as well as the grouting pressure P during the grouting process. j and grouting volume Q j The collected data is converted and transmitted to the control unit; the data processor (2) of the control unit preprocesses the multi-source data to eliminate the magnitude difference between gas pressure P, gas concentration C, and gas flow rate Q, and calculates the comprehensive index S(t): ； In the formula, S(t) is the comprehensive sealing status index at time t, P(t) is the gas pressure after treatment at time t, C(t) is the gas concentration after treatment at time t, Q(t) is the gas flow rate after treatment at time t, α, β, and γ are weighting coefficients, and α+β+γ=1. S3: Initial sealing: The sealing baffle (10) is sent into the sealing section (14) inside the extraction borehole (18), the grouting pump (1) is started, and gel-state sealing material is injected into the sealing section (14) through the grouting pipe (11). The grouting pressure is controlled, and the return flow meter (22) is used to monitor the return flow. When the sealing material overflows from the return pipe (12), the grouting is stopped, and the basic sealing structure is formed. S4: Dynamic continuous sealing. After the sealing structure is formed, the gas sensor (3) and the slurry sensor (4) transmit data to the control unit in real time. The data processor monitors the data in real time and performs data processing in step S2. The PLC controller (20) determines whether the dynamic grouting start-up conditions are met based on the pre-processed monitoring data. ①Initiation of early warning stage: Grouting pressure P collected by grout sensor (4) j Not lower than the set minimum grouting pressure P L If the gas concentration C collected by the gas sensor (3) is lower than the set concentration threshold C0 and the gas flow rate Q is lower than the set flow rate threshold Q0, the grouting warning is activated and grouting is prepared. ② Grouting start-up stage: When grouting is started, at the instant of start-up, due to the pressure relief gas concentration C and the grouting flow rate Q j The gas concentration C(t) changes by a decreasing trend. The ratio of the change in gas concentration C(t) after treatment to the time increment ∆t, i.e., the rate of change in concentration, reaches -0.

4. At the same time, the ratio of the change in grouting flow rate Q(t) after treatment to the time increment ∆t, i.e., the rate of change in flow rate, also reaches -0.

4. The PLC controller (20) generates a grouting command. If the ratio is less than -0.4, it indicates that the crack is expanding rapidly and an emergency grouting command needs to be triggered. The grouting command controls the grouting valve (19) to open and the grouting pump (1) to start through the signal transmission line (17), and dynamic grouting begins. When grouting is started, the rate of change in concentration and the rate of change in flow rate fluctuate between -0.1 and -0.4, and the slope gradually slows down. ③ Stable grouting stage: After grouting for a period of time, the gas concentration and flow rate show an upward trend. The rate of change of concentration and the rate of change of flow rate fluctuate between 0.1 and 0.

4. When the rate of change of concentration and the rate of change of flow rate exceed the set range, the PLC controller (20) sends an adjustment grouting command to the grouting pump (1) to reduce the amount of grout injected into the sealing section (14); when it is lower than the set range, the amount of grout injected into the sealing section (14) is increased. ④ Grouting stop stage: After the gas pressure sensor value stabilizes, when the gas concentration C reaches the set concentration threshold C0 and the gas flow rate Q reaches the set flow rate threshold Q0 or the concentration change rate and flow rate change rate are greater than 0.5, the PLC controller (20) generates a grouting termination command, controls the grouting pump (1) to stop, and closes the grouting valve (19) to complete the dynamic continuous sealing process. S5: Gas extraction. After the dynamic continuous sealing is completed, the downhole gas pipeline is connected to the gas extraction pipe (15) through a flange for extraction operation. During gas extraction, the gas pressure sensor (9), gas flow sensor (8), and gas concentration sensor (7) transmit data to the PLC controller (20) in real time and transmit the data to the mobile device (21). The mobile device (21) monitors the grouting and extraction status in real time. During the extraction process, the PLC controller (20) monitors the gas concentration C in real time. When the gas extraction concentration is lower than the set minimum gas concentration C, the gas extraction concentration is lower than the set minimum gas concentration C. L When the PLC controller (20) sends a stop extraction command, it automatically executes step S4. This process is repeated to achieve continuous grouting and efficient gas extraction.

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