High-gas coal seam mining method with cooperation of hydraulic fracturing pressure relief and high drainage roadway

Abstract

The invention belongs to the field of coal mine rock burst and gas control, and relates to a high-gas coal seam mining method with cooperation of hydraulic fracturing pressure relief and high drainage roadway, which comprises the following steps: constructing a trend high drainage roadway, and constructing a hydraulic fracturing drill hole and fracturing in an air return crossheading; constructing layer-crossing drilling holes from the trend high drainage roadway to the air return crossheading; tunneling an air return crossheading and ventilating; performing hydraulic fracturing drilling and fracturing in the open-off cut; constructing a layer-penetrating hole from the end part of the trend high drainage roadway to the open-off cut; tunneling a cut hole and ventilating; the air return crossheading is connected with the air return main roadway; bedding drilling and fracturing are carried out in self-air-return crossheading construction; and hydraulic fracturing drilling and fracturing are conducted on the transportation crossheading, the transportation crossheading is tunneled and ventilated, and working face stoping is conducted. Pressure relief is carried out before roadway tunneling, a smooth air flow path can be formed before roadway tunneling and in the tunneling process to extract gas, newly generated gas on a tunnel face can be rapidly extracted, gas extraction can be continuously carried out during stoping, and safety of the whole production process is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the field of prevention and control of rock bursts and gas in coal mines, and particularly relates to a mining method for high-gas coal seams that combines hydraulic fracturing pressure relief and high-extraction roadway cooperation. Background Art

[0002] Gas is easily attached to underground coal seams. Gas is a toxic gas, flammable and explosive, which is not conducive to coal production. In coal seams with rock bursts, the gas problem is more prominent. In the prior art, there are various means for treating rock bursts and gas. When driving a roadway, long boreholes can be constructed to relieve the pressure of the roadway and pre-drain the gas; alternatively, cross-cut boreholes can be constructed in the floor rock roadway for gas pre-drainage, and then the roadway can be driven. After the roadway driving is completed and before coal seam mining, bedding boreholes can be constructed in the roadway to fracture and relieve the pressure of the coal seam, extract the gas, and then the coal seam can be mined by the longwall caving method. When the gas content is very high, the gas generated by the pressure relief of coal seam mining can also be extracted by using a strike high-extraction roadway constructed in the roof rock formation during the coal seam mining process. These means have greatly improved the treatment effect of rock bursts and gas, and basically solved the harm caused by rock bursts and gas to coal mining. Among them, for high-gas coal seams, especially those containing rock bursts, multiple means are generally used for comprehensive treatment, but this will lead to low coal production efficiency. Therefore, how to integrate the existing various means of treating rock bursts and gas to achieve a synergistic effect and improve the roadway driving speed and working face production efficiency has become a research hotspot. Summary of the Invention

[0003] In view of the deficiencies of the above prior art, the present invention provides a mining method for high-gas coal seams that combines hydraulic fracturing pressure relief and high-extraction roadway cooperation, including the following steps:

[0004] S1: Construct a strike high-extraction roadway; construct hydraulic fracturing boreholes along the axial direction of the return airway in the return airway from the main haulage roadway to hydraulically fracture and relieve the pressure of the coal and rock mass in the return airway and its vicinity; construct cross-cut boreholes from the strike high-extraction roadway to the return airway.

[0005] S2: Drive the return airway and ventilate. The air flows from the main haulage roadway to the return airway, and then through the cross-cut boreholes to the strike high-extraction roadway.

[0006] S3: Construct hydraulic fracturing boreholes along the axial direction of the cut-through in the cut-through from the return airway to hydraulically fracture and relieve the pressure of the coal and rock mass in the cut-through and its vicinity; construct cross-cut boreholes from the end of the strike high-extraction roadway to the cut-through.

[0007] S4: Drive the cut-through and ventilate. The air flows from the main haulage roadway to the return airway, then to the cut-through, and through the cross-cut boreholes to the strike high-extraction roadway.

[0008] S5: Disconnect the connection between the return air crossheading and the main haulage roadway, and drive the return air crossheading in the reverse direction to connect it with the return airway; drill bedding holes from the return air crossheading towards the transport crossheading, and conduct hydraulic fracturing pressure relief through the bedding holes; drill hydraulic fracturing holes along the axial direction of the transport crossheading from the main haulage roadway to conduct hydraulic fracturing pressure relief on the coal and rock mass in the transport crossheading and its vicinity.

[0009] S6: Drive the transport crossheading. The air flows from the main haulage roadway to the transport crossheading, part of it passes through the bedding holes and their fracturing fissures to the return air crossheading, and part of it passes through the entire transport crossheading via the cutting roadway and then reaches the return air crossheading.

[0010] S7: After the roadway driving is completed, retain the strike high extraction roadway and the bedding holes; before coal mining, use the bedding holes to extract the gas in the coal seam of the working face extraction area; then conduct coal mining in the working face extraction area. During the coal mining process, use the strike high extraction roadway and the bedding holes to extract the gas in the coal seam of the working face extraction area.

[0011] Preferably, in step S1, the cross-cutting holes are arranged at intervals along the strike.

[0012] Preferably, in step S2, ventilation is carried out first before driving.

[0013] Preferably, in step S2, the driven return air crossheading is closed and supported at a certain distance behind the heading face, and the cross-cutting holes in the closed support area are no longer connected to the return air crossheading.

[0014] Preferably, in step S3, the bottom sections of the cross-cutting holes are arranged at intervals along the length direction of the cutting roadway.

[0015] Preferably, in step S4, ventilation is carried out first before driving.

[0016] Preferably, in step S4, the driven cutting roadway is closed and supported at a certain distance behind the heading face, and the cross-cutting holes in the closed support area are no longer connected to the cutting roadway.

[0017] Preferably, in step S5, the bedding holes are arranged at intervals along the strike, and the bedding holes are constructed within the range of the transport crossheading.

[0018] Preferably, in step S5, the hydraulic fracturing fissures of the bedding holes are interconnected with each other and the hydraulic fracturing fissures of the bedding holes are connected to the hydraulic fracturing fissures of the hydraulic fracturing holes in the transport crossheading.

[0019] Preferably, in step S6, ventilation is carried out first before driving.

[0020] The beneficial technical effects of the present invention are as follows: 1. The mining method of the present invention uses a high-drainage roadway to construct cross-measure boreholes, and cooperates with hydraulic fracturing boreholes and their fracturing fissures in the return airway and the cutting roadway to form a smooth path for gas extraction. It can relieve the pressure of the roadway, quickly extract the newly generated gas at the heading face, and avoid the impact of rock burst and gas on the excavation of the return airway and the cutting roadway.

[0021] 2. The mining method of the present invention first constructs the return airway, and constructs bedding boreholes in the return airway to communicate with the hydraulic fracturing boreholes and their fracturing fissures in the transportation airway, relieves the pressure of the coal seam in the transportation airway and the mining area, and forms a smooth path for gas extraction. It can also quickly extract the newly generated gas at the heading face and avoid the impact of rock burst and gas on the excavation of the transportation airway.

[0022] 3. The present invention can relieve the pressure and extract gas from the entire working face during the tunneling process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic plan view of borehole layout during the excavation of the return airway of the present invention;

[0024] Figure 2 is a schematic sectional view of borehole layout during the excavation of the return airway of the present invention;

[0025] Figure 3 is a schematic plan view of borehole layout during the excavation of the cutting roadway of the present invention;

[0026] Figure 4 is a schematic sectional view of borehole layout during the excavation of the cutting roadway of the present invention;

[0027] Figure 5 is a schematic plan view of borehole layout during the excavation of the transportation airway of the present invention;

[0028] Figure 6 is a schematic plan view after the excavation of the roadway of the present invention is completed and during the coal face mining;

[0029] In the figure, 1 - return main roadway or return upcast shaft, 2 - transportation main roadway or transportation upcast shaft, 3 - return airway, 4 - strike high-drainage roadway, 5 - transportation airway, 6 - cross-measure borehole, 7 - hydraulic fracturing borehole, 8 - cutting roadway, 9 - bedding borehole. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following introduces the specific implementation manners of the present invention in conjunction with the drawings.

[0031] As Figures 1 - 6 shown, the present invention proposes a high-gas coal seam mining method that combines hydraulic fracturing pressure relief and high-drainage roadway cooperation, including the following steps:

[0032] S1: As Figures 1 - 2As shown in the figure, a strike high - extraction roadway 4 is constructed along the strike on the roof inside the return airway 3. The common construction position and function of the strike high - extraction roadway 4 (extracting the gas generated during the coal face mining) are well - known in the art and will not be elaborated here. The strike high - extraction roadway 4 is constructed in the rock formation and is not affected by gas disasters and coal seam impacts.

[0033] A hydraulic fracturing borehole 7 is constructed from the main haulage roadway 2 at the axial center of the return airway 3 to conduct hydraulic fracturing and pressure relief on the coal and rock mass in the return airway 3 and its vicinity. The hydraulic fracturing borehole 7 preferably has a relatively large diameter. Preferably, after hydraulic fracturing, a proppant is injected into the fracturing cracks to support the fracturing cracks.

[0034] A cross - seam borehole 6 is constructed from the strike high - extraction roadway 4 to the hydraulic fracturing range of the return airway 3. The cross - seam borehole 6 is connected to the hydraulic fracturing borehole 7 and its fracturing cracks. The cross - seam boreholes 6 are arranged at intervals along the strike in rows.

[0035] S2: As Figures 1 - 2 shown, negative pressure ventilation is carried out using the strike high - extraction roadway 4. The air flow direction is: entering from the main haulage roadway 2 into the hydraulic fracturing borehole 7 and its fracturing cracks at the return airway 3, carrying the gas in the coal seam, and then flowing through the cross - seam borehole 6 to the strike high - extraction roadway 4.

[0036] Under the above ventilation path, when driving the return airway 3 from the main haulage roadway 2, before driving, the coal seam in the return airway 3 has been pressure - relieved by hydraulic fracturing through the hydraulic fracturing borehole 7, and gas pre - extraction has been carried out, which can provide a relatively safe environment for the driving of the return airway 3. The driven return airway 3 is closed and supported at a certain distance behind the working face. The cross - seam boreholes 6 in the closed - support area are no longer connected to the return airway 3. During the process of driving the return airway 3, part of the newly generated gas at the working face flows out to the strike high - extraction roadway 4 through the cross - seam boreholes 6 exposed near the working face, and part enters the cross - seam boreholes 6 through the hydraulic fracturing borehole 7 and its fracturing cracks in the un - driven return airway 3 and then flows out to the strike high - extraction roadway 4. The coal dust and gas generated during the driving at the working face flow through the same path.

[0037] S3: As Figures 3 - 4 shown, a hydraulic fracturing borehole 7 is constructed from the return airway 3 at the axial center of the cut - through 8 to conduct hydraulic fracturing and pressure relief on the cut - through 8 and its vicinity coal and rock mass. The hydraulic fracturing borehole 7 preferably has a relatively large diameter. Preferably, after hydraulic fracturing, a proppant is injected into the fracturing cracks to support the fracturing cracks.

[0038] A cross - seam borehole 6 is constructed from the end of the strike high - extraction roadway 4 to the hydraulic fracturing range of the cut - through 8. The cross - seam borehole 6 is connected to the hydraulic fracturing borehole 7 and the fracturing cracks. The bottom section of the cross - seam borehole 6 is arranged at intervals along the length direction of the cut - through 8.

[0039] S4: As Figures 3 - 4As shown in the figure, a negative pressure air extraction is carried out by using the crossheading 4 along the strike. The air flow direction is as follows: it enters the return airway 3 from the main haulage roadway 2, then enters the hydraulic fracturing borehole 7 and its fracturing fissures at the open-off cut 8. After carrying the gas in the coal seam, it goes through the cross-cut borehole 6 to the crossheading 4 along the strike;

[0040] Under the above ventilation path, the open-off cut 8 is driven from the return airway 3. Before driving, the coal seam in the open-off cut 8 has been depressurized by the hydraulic fracturing of the hydraulic fracturing borehole 7, and pre-extraction of gas has been carried out, which can provide a relatively safe environment for the driving of the open-off cut 8; the open-off cut 8 driven is closed and supported at a certain distance behind the face. The cross-cut borehole 6 in the closed support area is no longer connected to the open-off cut 8; during the process of driving the open-off cut 8, part of the newly generated gas at the face flows out to the crossheading 4 along the strike through the cross-cut borehole 6 exposed near the face, and part enters the cross-cut borehole 6 through the hydraulic fracturing borehole 7 and its fracturing fissures in the un-driven open-off cut 8 and then flows out to the crossheading 4 along the strike; the coal dust and gas generated during the driving at the face flow through the same path;

[0041] S5: As Figure 5 shown in the figure, the connection between the return airway 3 and the main haulage roadway 2 is disconnected, and the return airway 3 is driven in the reverse direction to connect it with the return airway 1;

[0042] A hydraulic fracturing borehole 7 is constructed at the axial center of the transport roadway 5 from the main haulage roadway 2 to carry out hydraulic fracturing and pressure relief on the transport roadway 5 and its adjacent coal and rock mass; the hydraulic fracturing borehole 7 preferably has a larger diameter; preferably, after hydraulic fracturing, a proppant is injected into the fracturing fissures to support the fracturing fissures;

[0043] A bedding borehole 9 is constructed from the return airway 3 to the transport roadway 5. The bedding boreholes 9 are arranged at intervals along the strike and are constructed within the range of the transport roadway 5; the coal seam is depressurized by hydraulic fracturing through the bedding boreholes 9. The fracturing fissures of the bedding boreholes 9 are interconnected with each other, and the fracturing fissures of the bedding boreholes 9 are connected with the fracturing fissures of the hydraulic fracturing borehole 7 in the transport roadway 5; preferably, after hydraulic fracturing, a proppant is injected into the fracturing fissures to support the fracturing fissures;

[0044] S6: As Figure 5 shown in the figure, a negative pressure air extraction is carried out by using the return airway 3. The air flow direction is as follows: it enters the hydraulic fracturing borehole 7 and its fracturing fissures in the transport roadway 5 from the main haulage roadway 2. Part of it flows to the return airway 3 through the bedding borehole 9 and its fracturing fissures, and part flows to the open-off cut 8 and then to the return airway 3 after passing through the hydraulic fracturing borehole 7 and its fracturing fissures in the entire transport roadway 5. During this process, the air will carry away the gas overflowing from the coal seam;

[0045] Under the above ventilation path, when driving the transport crossheading 5 from the main haulage roadway 2, before driving, the coal seam in the transport crossheading 5 has been depressurized by hydraulic fracturing through the hydraulic fracturing boreholes 7, and gas drainage has been carried out, which can provide a relatively safe environment for the driving of the transport crossheading 5; the driven transport crossheading 5 is supported at a certain distance behind the heading face, and the bedding boreholes 9 are not sealed during support; during the process of driving the transport crossheading 5, part of the newly generated gas at the heading face flows out to the return airway 3 through the bedding boreholes 9 and their fracturing fissures near the heading face, and part flows to the cut-through roadway 8 after passing through the hydraulic fracturing boreholes 7 and their fracturing fissures in the un-driven transport crossheading 5, and then flows out to the return airway 3; the coal dust and gas generated during driving at the heading face flow through the same path;

[0046] S7: As Figure 6 shown, after the driving of the roadway is completed, the strike high-extraction roadway 4 and the bedding boreholes 9 are retained, and the bedding boreholes 9 are used to continue draining the gas in the coal seam in the working face extraction area; the working face extraction area is mined by a shearer in cooperation with hydraulic supports. During the mining process, the strike high-extraction roadway 4 and the bedding boreholes 9 are continuously used to drain the gas in the coal seam in the working face extraction area; at this time, the cross-cut boreholes 6 can also improve the connectivity between the goaf and the strike high-extraction roadway 4, and improve the gas drainage effect of the strike high-extraction roadway 4 on the goaf gas.

[0047] The above main haulage roadway 2 can also be a haulage rise 2, and the corresponding return airway 1 is a return rise 1.

[0048] The present invention is not limited to the above best implementation manner. Anyone can obtain various other forms of methods under the inspiration of the present invention. However, any technical solutions that are the same as or similar to the present application fall within the protection scope of the present invention.

Claims

1. A mining method for high-gas coal seams that combines hydraulic fracturing pressure relief with high-extraction roadway, characterized in that, It includes the following steps: S1: Construct the strike high-drainage roadway; construct hydraulic fracturing boreholes along the axial direction of the return airway from the main haulage roadway in the return airway to perform hydraulic fracturing pressure relief on the coal and rock mass in the return airway and its vicinity; construct cross-measurement boreholes from the strike high-drainage roadway to the return airway; S2: Drive the return airway and ventilate. The air flows from the main haulage roadway to the return airway, and then through the cross-measurement boreholes to the strike high-drainage roadway; S3: Construct hydraulic fracturing boreholes along the axial direction of the cut-through in the return airway to perform hydraulic fracturing pressure relief on the cut-through and its vicinity coal and rock mass; construct cross-measurement boreholes from the end of the strike high-drainage roadway to the cut-through; S4: Drive the cut-through and ventilate. The air flows from the main haulage roadway to the return airway and then to the cut-through, and through the cross-measurement boreholes to the strike high-drainage roadway; S5: Disconnect the connection between the return airway and the main haulage roadway, and drive the return airway in the reverse direction to connect it with the return airway. Construct bedding boreholes from the return airway to the direction of the haulage airway, and perform hydraulic fracturing pressure relief through the bedding boreholes; construct hydraulic fracturing boreholes along the axial direction of the haulage airway in the haulage airway from the main haulage roadway to perform hydraulic fracturing pressure relief on the haulage airway and its vicinity coal and rock mass; S6: Drive the haulage airway. The air flows from the main haulage roadway to the haulage airway, part of it through the bedding boreholes to the return airway, and part of it through the entire haulage airway through the cut-through and then to the return airway; S7: After the roadway driving is completed, retain the strike high-drainage roadway and bedding boreholes; before coal mining, use the bedding boreholes to extract the gas in the coal seam of the working face mining area; then carry out coal mining in the working face mining area. During the coal mining process, use the strike high-drainage roadway and bedding boreholes to extract the gas in the coal seam of the working face mining area.

2. The high-gas coal seam mining and excavation method by cooperation of hydraulic fracturing pressure relief and high-extraction roadway according to claim 1, characterized in that In step S1, the cross-measurement boreholes are arranged at intervals along the strike.

3. The high-gas coal seam mining and excavation method combining hydraulic fracturing pressure relief with high-extraction roadway is characterized in that, according to claim 1, In step S2, ventilate first before driving.

4. The high-gas coal seam mining and excavation method combining hydraulic fracturing pressure relief with high-extraction roadway according to any one of claims 1-3, characterized in that, In step S2, lagging behind the heading face, the driven return airway is closed and supported, and the cross-measurement boreholes in the closed support area are no longer connected to the return airway.

5. The high-gas coal seam mining and excavation method of hydraulic fracturing pressure relief and high-extraction roadway cooperation according to claim 1, characterized in that In step S3, the bottom sections of the cross-measurement boreholes are arranged at intervals along the length direction of the cut-through.

6. The high-gas coal seam mining and excavation method combining hydraulic fracturing pressure relief with high-drainage roadway is characterized in that, In step S4, ventilate first before driving.

7. The high-gas coal seam mining and excavation method combining hydraulic fracturing pressure relief with high-extraction roadway according to claim 1 or 5 or 6, characterized in that, In step S4, lagging behind the heading face, the driven cut-through is closed and supported, and the cross-measurement boreholes in the closed support area are no longer connected to the cut-through.

8. The high-gas coal seam mining and excavation method combining hydraulic fracturing pressure relief with high-extraction roadway is characterized in that, In step S5, the bedding boreholes are arranged at intervals along the strike, and the bedding boreholes are constructed within the range of the haulage airway.

9. The high-gas coal seam mining and excavation method of hydraulic fracturing pressure relief and high-extraction roadway cooperation according to claim 8, characterized in that In step S5, the hydraulic fracturing fissures of the bedding boreholes are interconnected with each other and the hydraulic fracturing fissures of the bedding boreholes are connected to the hydraulic fracturing fissures of the hydraulic fracturing boreholes in the haulage airway.

10. The high-gas coal seam mining and excavation method of hydraulic fracturing pressure relief and high-extraction roadway cooperation according to claim 9, characterized in that, In step S6, ventilate first before driving.

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