A steeply inclined coal seam unmanned working face mining method based on hydraulic or gas fracturing

Abstract

The application discloses a kind of steeply inclined coal seam unmanned working face mining method based on hydraulic or gas fracturing, belong to coal mining technical field, including S1 geological survey and process scheme formulation, S2 directional drilling construction and face perforation, S3 self-adapting fracturing permeability and roof weakening, S4 synchronous gas extraction operation, S5 upwardly inclined coal drawing and intelligent coal gangue isolation, S6 roadway full-face sealing plugging, S7 goaf gas closed-loop management and S8 full-process unmanned operation and process optimization.The application can realize steeply inclined coal seam intrinsic safety production, improve coal and gas resource utilization, green low-carbon emission reduction, reduce labor input, and the comprehensive economic benefit and environmental protection benefit are outstanding.

Description

Technical Field

[0001] This invention belongs to the field of coal mining technology, specifically relating to a method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing. Background Technology

[0002] my country has abundant reserves of steeply inclined coal seams, which are a key component of the domestic coal energy supply. Under the industry policy guidance of intelligent coal mining to reduce manpower and increase efficiency, and green and low-carbon mining, the existing traditional mining techniques such as blasting and pseudo-inclined simple fully mechanized mining are constrained by the inherent geological conditions caused by the steep inclination of the coal seam, such as the self-flow of gangue, the concentration of ground stress, and the chaotic distribution of gas. These techniques generally have many problems, such as the need for manual on-site operation at the working face, the blind selection of fracturing media without differentiation and the inability to target and weaken the roof, the difficulty in controlling pressure disasters, the separate construction of fracturing and gas drainage leading to excessive gas accumulation, the simple construction of gangue retaining walls and roadway sealing facilities which are prone to air leakage and gangue migration, the fixed process parameters year after year resulting in low coal recovery rates, and the pollution of water, soil and air caused by fracturing waste liquid and waste gas. These problems cannot simultaneously meet the industry requirements of safe, efficient and green mining. Summary of the Invention

[0003] To achieve the above objectives, this invention provides a method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing, employing the following technical solution: A method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing includes: S1. Geological Survey and Process Plan Formulation: Data on coal and rock, fractures, in-situ stress, and roof pressure at the working face are collected using ground-penetrating radar and channel wave seismic exploration. The geological conditions of the working face are analyzed, and hydraulic or gas fracturing media are matched according to the coal seam occurrence characteristics. The relevant parameters and operation sequence for drilling, fracturing, and coal release are determined, and an unmanned mining construction plan is formulated. After perforation, mechanical segmented sealing devices are used to seal each section of the borehole to isolate the borehole wall from the roadway space and prevent subsequent fracturing media from overflowing and leaking. S2. Directional drilling and face perforation: Directional drilling is carried out in steeply inclined coal seams using a cluster of drilling rigs, and face-oriented directional perforation is completed using segmented tools; directional drilling is arranged along the dip or strike of the coal seam, and the drilling trajectory is parallel to the roof of the coal seam; face-oriented and directional perforation is carried out at designated locations along the direction of the maximum horizontal principal stress or the weak surface of the roof and floor of the coal seam to actively control the propagation path of the main fracture; S3. Adaptive fracturing and roof weakening: Depending on the type of medium, hydraulic pressure stabilization fracturing or gas pulse fracturing is used to construct a three-dimensional fracture network in the coal seam, while extending the fractures to weaken the roof structure, release roof pressure in advance, and prevent initial and periodic pressure disasters. S4. Synchronous gas extraction operation: During the fracturing operation, the intelligent extraction system is started simultaneously. The extraction negative pressure is dynamically adjusted through adjacent boreholes and pressure relief holes to simultaneously extract the gas from the coal seam analysis and displacement. S5. Inclined Coal Discharge and Intelligent Coal and Gangue Isolation: The working face adopts an inclined layout with the coal discharge port higher than the goaf to prevent the old mine gangue from sliding in. Relying on the liftable end support, retractable fully enclosed baffle and shock-absorbing adjustable coal retaining plate, the roadway is fully blocked, the impact of coal and gangue is buffered, and unmanned precise coal guiding and discharge is achieved. S6. Full-section sealing of the roadway: A customized windbreak wall with air door panels is constructed in the working face roadway. The panel interfaces are fixed and sealed, and the joints of the top and bottom plates are sealed with sprayed grout to achieve full-section airtightness and prevent air leakage in the roadway. S7. Closed-loop control of gas in goaf: High-level long boreholes are used to extract gas accumulated in the goaf. When the gas extraction effect is insufficient, the dedicated return airway ventilation mode is automatically switched to prevent gas accidents caused by pressure disturbance. S8. Full-process unmanned operation and process optimization: Drilling, sealing, fracturing, extraction, coal release, and support are all completed automatically by a group of automated equipment, and the working face is unmanned throughout the process; after each mining cycle is completed, the mining parameters for the next cycle are dynamically optimized based on the actual mining conditions on site, so as to realize closed-loop optimization of the mining process.

[0004] Furthermore, in step S1, high-gas and hard coal seams are matched with gas fracturing media, which are nitrogen, carbon dioxide or high-pressure air; low-gas and soft coal seams are matched with hydraulic fracturing media, which are water.

[0005] Furthermore, in step S3, the fracturing medium is water or gas; when water is used for fracturing, it is pressurized by a high-pressure pump and injected into the borehole to complete hydraulic fracturing. When gas is used as the fracturing medium, the gas is CO2 or N2, and the high-pressure state is to pressurize and heat the liquid or liquid to a supercritical state or a high-pressure gaseous state; by adjusting the fracturing parameters, the fracture extends to the direct roof or the old roof of the coal seam, and the roof is weakened by fracturing, and the initial pressure and periodic pressure step distance are controlled.

[0006] Furthermore, in step S5, the retractable fully enclosed baffle of the end support is a multi-stage hydraulic telescopic structure, which can adaptively adjust the extension length according to the height of the roadway to achieve full-section, dead-angle-free sealing of the roadway.

[0007] Furthermore, the coal retaining plate includes two layers of steel plates and a shock-absorbing spring; the shock-absorbing spring is disposed between the two layers of steel plates, and both ends of the shock-absorbing spring are respectively connected to the two layers of steel plates, which can buffer the impact of coal and gangue and reduce the force on the retaining plate.

[0008] Furthermore, in step S6, an isolation windbreak wall with a concave-convex interface damper plate is constructed in the working face roadway; the concave-convex interface damper plate adopts a modular splicing structure, with the concave and convex parts interlocking and fitting together, and is sealed with adhesive and sprayed with grout to prevent air leakage in the roadway and prevent spontaneous combustion of residual coal and accumulation of gas turbulence.

[0009] Furthermore, a high-level long borehole terminal hole is set above the fracture zone of the goaf extraction area to accurately cover the gas accumulation area and achieve directional and efficient extraction.

[0010] Furthermore, in step S8, data on top coal recovery rate, gas extraction concentration, roof pressure step distance, and support stress are collected on-site, and the parameters of borehole spacing, fracturing pressure, fracturing time, and coal release step distance are dynamically adjusted according to the actual working conditions.

[0011] Furthermore, the entire process of fracturing, sealing, gas extraction, coal release, and roadway sealing requires no manual on-site operation, achieving essentially unmanned mining of steeply inclined coal seams.

[0012] The unmanned mining method for steeply inclined coal seams based on hydraulic or gas fracturing provided by this invention has the following beneficial effects: This invention matches the fracturing medium to the coal seam's hardness and gas occurrence conditions, combining a complete set of technical solutions including directional perforation and controlled fracturing to weaken the roof, simultaneous fracturing and gas extraction, inclined mining with buffered coal retaining support, modular fully sealed roadway plugging, and closed-loop self-optimization of mining parameters. Relying on fully automated equipment, it achieves unmanned operation of the working face, eliminating safety hazards such as rockfall, gas explosion, and spontaneous combustion of residual coal at the source. Fully developed coal seam fractures, combined with precise coal release, significantly improve coal resource recovery rate, simultaneously increasing gas extraction efficiency and realizing gas resource utilization. Gas fracturing enables carbon dioxide formation sealing, and segmented sealing prevents fracturing medium leakage and soil and water pollution, meeting the requirements of dual-carbon green mining. Automated production significantly reduces underground labor and material losses, compressing production costs. Furthermore, water and gas pressure processes can be flexibly switched, adapting to the transformation and new construction projects of different types of steeply inclined mines in China. It boasts outstanding advantages in safety, resource benefits, environmental protection, and industrial application. Attached Figure Description

[0013] Figure 1 This is a flowchart of the unmanned working face mining method for steeply inclined coal seams based on hydraulic or gas fracturing according to the present invention. Detailed Implementation

[0014] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more easily understood, specific embodiments of the present invention are described below.

[0015] Example 1

[0016] Reference Figure 1 A method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing, comprising: S1. Geological Survey and Process Plan Formulation: Data on coal and rock, fractures, in-situ stress, and roof pressure at the working face are collected using ground-penetrating radar and channel wave seismic exploration. The geological conditions of the working face are analyzed, and hydraulic or gas fracturing media are matched according to the coal seam occurrence characteristics. The relevant parameters and operation sequence for drilling, fracturing, and coal release are determined, and an unmanned mining construction plan is formulated. After perforation, mechanical segmented sealing devices are used to seal each section of the borehole to isolate the borehole wall from the roadway space and prevent subsequent fracturing media from overflowing and leaking. S2. Directional Drilling and Targeted Perforation: A cluster of drilling rigs is used to conduct directional drilling within steeply inclined coal seams, followed by targeted directional perforation using segmented tools. Directional boreholes are arranged along the dip or strike of the coal seam, with the borehole trajectory parallel to the coal seam roof. Segmented tools are used at designated locations along the direction of maximum horizontal principal stress or the weak surface of the coal seam's roof and floor to actively control the propagation path of the main fractures. S3. Adaptive fracturing and roof weakening: Depending on the type of medium, hydraulic pressure stabilization fracturing or gas pulse fracturing is used to construct a three-dimensional fracture network in the coal seam, while extending the fractures to weaken the roof structure, release roof pressure in advance, and prevent initial and periodic pressure disasters. S4. Synchronous gas extraction operation: During the fracturing operation, the intelligent extraction system is started simultaneously. The extraction negative pressure is dynamically adjusted through adjacent boreholes and pressure relief holes to simultaneously extract the gas from the coal seam analysis and displacement. S5. Inclined Coal Discharge and Intelligent Coal and Gangue Isolation: The working face adopts an inclined layout with the coal discharge port higher than the goaf to prevent the old mine gangue from sliding in. Relying on the liftable end support, retractable fully enclosed baffle and shock-absorbing adjustable coal retaining plate, the roadway is fully blocked, the impact of coal and gangue is buffered, and unmanned precise coal guiding and discharge is achieved. S6. Full-section sealing of the roadway: A customized windbreak wall with air door panels is constructed in the working face roadway. The panel interfaces are fixed and sealed, and the joints of the top and bottom plates are sealed with sprayed grout to achieve full-section airtightness and prevent air leakage in the roadway. S7. Closed-loop control of gas in goaf: High-level long boreholes are used to extract gas accumulated in the goaf. When the gas extraction effect is insufficient, the dedicated return airway ventilation mode is automatically switched to prevent gas accidents caused by pressure disturbance. S8. Full-process unmanned operation and process optimization: Drilling, sealing, fracturing, extraction, coal release, and support are all completed automatically by a group of automated equipment, and the working face is unmanned throughout the process; after each mining cycle is completed, the mining parameters for the next cycle are dynamically optimized based on the actual mining conditions on site, so as to realize closed-loop optimization of the mining process.

[0017] In this embodiment, in step S1, high-gas and hard coal seams are matched with gas fracturing media, which are nitrogen, carbon dioxide or high-pressure air; low-gas and soft coal seams are matched with hydraulic fracturing media, which are water.

[0018] In this embodiment, in step S3, the fracturing medium is water or gas; when water is used for fracturing, it is pressurized by a high-pressure pump and injected into the borehole to complete hydraulic fracturing. When gas is used as the fracturing medium, the gas is CO2 or N2. The high-pressure state is achieved by pressurizing and heating the liquid or liquid to a supercritical state or a high-pressure gaseous state. By adjusting the fracturing parameters, the fractures are extended to the direct roof or the old roof of the coal seam, and the roof is weakened by fracturing. The initial pressure and the periodic pressure step distance are controlled.

[0019] In this embodiment, in step S5, the retractable fully enclosed baffle of the end support is a multi-stage hydraulic telescopic structure, which can adaptively adjust the extension length according to the height of the roadway to achieve full-section sealing of the roadway without dead angles.

[0020] In this embodiment, the coal retaining plate includes two layers of steel plates and a shock-absorbing spring; the shock-absorbing spring is disposed between the two layers of steel plates, and both ends of the shock-absorbing spring are connected to the two layers of steel plates respectively, which can buffer the impact of coal and gangue and reduce the force on the retaining plate.

[0021] In this embodiment, in step S6, an isolation windbreak wall with a concave-convex interface damper plate is constructed in the working face roadway; the concave-convex interface damper plate adopts a modular splicing structure, with the concave and convex parts interlocking and fitting together, and is sealed with adhesive and sprayed with grout to prevent air leakage in the roadway and prevent spontaneous combustion of residual coal and accumulation of gas turbulence.

[0022] In this embodiment, a high-position long borehole terminal hole is set above the fracture zone of the goaf extraction area to accurately cover the gas accumulation area and achieve directional and efficient extraction.

[0023] In this embodiment, in step S8, the top coal recovery rate, gas extraction concentration, roof pressure step distance, and support stress data are collected on site, and the drilling spacing, fracturing pressure, fracturing time, and coal release step distance parameters are dynamically adjusted according to the actual working conditions.

[0024] In this embodiment, the entire process of fracturing, sealing, gas extraction, coal release, and roadway plugging does not require manual on-site operation, realizing essentially unmanned mining of steeply inclined coal seams.

[0025] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing, characterized in that, include: S1. Geological Survey and Process Plan Formulation: Data on coal and rock, fractures, in-situ stress, and roof pressure at the working face are collected using ground-penetrating radar and channel wave seismic exploration. The geological conditions of the working face are analyzed, and hydraulic or gas fracturing media are matched according to the coal seam occurrence characteristics. The relevant parameters and operation sequence for drilling, fracturing, and coal release are determined, and an unmanned mining construction plan is formulated. After perforation, mechanical segmented sealing devices are used to seal each section of the borehole to isolate the borehole wall from the roadway space and prevent subsequent fracturing media from overflowing and leaking. S2. Directional drilling and face perforation: Directional drilling is carried out in steeply inclined coal seams using a cluster of drilling rigs, and face-oriented directional perforation is completed using segmented tools; directional drilling is arranged along the dip or strike of the coal seam, and the drilling trajectory is parallel to the roof of the coal seam; face-oriented and directional perforation is carried out at designated locations along the direction of the maximum horizontal principal stress or the weak surface of the roof and floor of the coal seam to actively control the propagation path of the main fracture; S3. Adaptive fracturing and roof weakening: Depending on the type of medium, hydraulic pressure stabilization fracturing or gas pulse fracturing is used to construct a three-dimensional fracture network in the coal seam, while extending the fractures to weaken the roof structure, release roof pressure in advance, and prevent initial and periodic pressure disasters. S4. Synchronous gas extraction operation: During the fracturing operation, the intelligent extraction system is started simultaneously. The extraction negative pressure is dynamically adjusted through adjacent boreholes and pressure relief holes to simultaneously extract the gas from the coal seam analysis and displacement. S5. Inclined Coal Discharge and Intelligent Coal and Gangue Isolation: The working face adopts an inclined layout with the coal discharge port higher than the goaf to prevent the old mine gangue from sliding in. Relying on the liftable end support, retractable fully enclosed baffle and shock-absorbing adjustable coal retaining plate, the roadway is fully blocked, the impact of coal and gangue is buffered, and unmanned precise coal guiding and discharge is achieved. S6. Full-section sealing of the roadway: A customized windbreak wall with air door panels is constructed in the working face roadway. The panel interfaces are fixed and sealed, and the joints of the top and bottom plates are sealed with sprayed grout to achieve full-section airtightness and prevent air leakage in the roadway. S7. Closed-loop control of gas in goaf: High-level long boreholes are used to extract gas accumulated in the goaf. When the gas extraction effect is insufficient, the dedicated return airway ventilation mode is automatically switched to prevent gas accidents caused by pressure disturbance. S8. Full-process unmanned operation and process optimization: Drilling, sealing, fracturing, extraction, coal release, and support are all completed automatically by a group of automated equipment, and the working face is unmanned throughout the process; after each mining cycle is completed, the mining parameters for the next cycle are dynamically optimized based on the actual mining conditions on site, so as to realize closed-loop optimization of the mining process.

2. The method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing according to claim 1, characterized in that, In step S1, high-gas and hard coal seams are matched with gas fracturing media, which are nitrogen, carbon dioxide or high-pressure air; low-gas and soft coal seams are matched with hydraulic fracturing media, which are water.

3. The method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing according to claim 1, characterized in that, In step S3, the fracturing medium is water or gas; when water is used for fracturing, it is pressurized by a high-pressure pump and injected into the borehole to complete hydraulic fracturing. When gas is used as the fracturing medium, the gas is CO2 or N2, and the high-pressure state is to pressurize and heat the liquid or liquid to a supercritical state or a high-pressure gaseous state; by adjusting the fracturing parameters, the fracture extends to the direct roof or the old roof of the coal seam, and the roof is weakened by fracturing, and the initial pressure and periodic pressure step distance are controlled.

4. The method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing according to claim 1, characterized in that, In step S5, the retractable fully enclosed baffle of the end support is a multi-stage hydraulic telescopic structure, which can adaptively adjust the extension length according to the height of the roadway to achieve full-section sealing of the roadway without dead angles.

5. The method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing according to claim 1, characterized in that, The coal retaining plate includes two layers of steel plates and a shock-absorbing spring; the shock-absorbing spring is disposed between the two layers of steel plates, and both ends of the shock-absorbing spring are respectively connected to the two layers of steel plates, which can buffer the impact of coal and gangue and reduce the force on the retaining plate.

6. The method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing according to claim 1, characterized in that, In step S6, a windbreak wall with a concave-convex interface damper plate is constructed in the working face roadway. The concave-convex interface damper plate adopts a modular splicing structure, with the concave and convex parts interlocking and fitting together. It is sealed with adhesive and sprayed with grout to prevent air leakage in the roadway and to prevent spontaneous combustion of residual coal and accumulation of gas turbulence.

7. The method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing according to claim 1, characterized in that, The high-position long borehole extraction method involves setting a final borehole above the fracture zone of the goaf, precisely covering the gas accumulation area and achieving directional and efficient extraction.

8. The method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing according to claim 1, characterized in that, In step S8, data on top coal recovery rate, gas extraction concentration, roof pressure step distance, and support stress are collected on-site. Based on the actual working conditions, the parameters of borehole spacing, fracturing pressure, fracturing time, and coal release step distance are dynamically adjusted.

9. The method for unmanned mining of steeply inclined coal seams based on hydraulic or gas fracturing according to claim 1, characterized in that, The entire process of fracturing, sealing, gas extraction, coal release, and roadway plugging requires no manual on-site operation, achieving essentially unmanned mining of steeply inclined coal seams.

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