Deep coal seam mining method of hydraulic fracturing pressure relief and layer-penetrating borehole extraction cooperation

Abstract

The present application belongs to the field of deep coal seam mining, and particularly relates to a deep coal seam mining method of hydraulic fracturing pressure relief and through-hole drilling extraction cooperation; the present application uses the separation layer generated by coal seam mining as a channel for gas migration to replace the traditional high extraction roadway, uses through-hole drilling to connect the coal seam and the separation layer, and then connects the separation layer from the gas extraction well constructed from the ground, so that the gas resolved before and after the coal seam mining can be extracted from the ground, which greatly reduces the engineering quantity while ensuring the gas control effect; further, an auxiliary roadway is constructed in the O-shaped ring, and a through-hole drilling is constructed in the auxiliary roadway, so as to facilitate the extraction of the gas generated by the working face mining, facilitate the construction of the through-hole drilling, and reduce the interference of the through-hole drilling construction on the normal coal mining work. In addition, since the development range of the separation layer is approximately the same as the mining range of the working face, the gas extraction method in the present application can extract the gas in the entire working face mining range, and only one gas extraction well needs to be constructed.

Description

Technical Field

[0001] This invention belongs to the field of deep coal seam mining, specifically involving a deep coal seam mining method that combines hydraulic fracturing and pressure relief with cross-seam drilling extraction. Background Technology

[0002] As coal seams deepen, the pressure they bear increases, making them prone to rockbursts during deep coal seam mining. Coal seams often contain associated gas, which is difficult to dislodge and can easily lead to gas disasters during mining. Hydraulic fracturing and pre-drainage of gas before mining are crucial for preventing rockbursts and gas disasters. However, the amount of gas removed during pre-drainage is limited, with most gas dislodged during mining. Therefore, improving gas drainage efficiency during coal seam mining is key to solving gas disaster problems. Top drainage roadways are an important method for gas drainage during coal seam mining; however, their construction within rock strata is time-consuming, labor-intensive, and costly, making them unsuitable for high-yield mines. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a deep coal seam mining method that combines hydraulic fracturing and pressure relief with cross-layer drilling for extraction. This method utilizes the delamination layer generated during coal seam mining as a channel for gas migration, replacing the traditional high-efficiency extraction roadway. Cross-layer drilling connects the coal seam and the delamination layer, and gas extraction wells are constructed from the surface to connect the delamination layer. This allows for the extraction of gas separated before and after coal seam mining from the surface, significantly reducing the amount of engineering work while ensuring effective gas control. The specific steps include the following:

[0004] S1: Construct the return airway and transport airway and connect them with a cut-in; construct a guide roadway at the stop-mining position of the working face to connect the return airway and transport airway; S2: Within the expected O-ring, construct the first auxiliary airway along the strike on the side of the return airway to connect the cut-in and guide roadway, and construct the second auxiliary airway along the strike on the side of the transport airway to connect the cut-in and guide roadway; S3: Construct in-seam boreholes from the first and second auxiliary airways within the working face, use the in-seam boreholes to perform hydraulic fracturing on the coal seam to relieve pressure on the coal seam, and then use the in-seam boreholes to pre-drain gas from the coal seam in the working face. S4: Simultaneously, select a delamination layer close to the water-conducting fracture zone as the gas transport plane channel, and construct a gas extraction well from the ground to the selected delamination layer; S5: In the first and second auxiliary horizontal roadways, construct a cross-layer borehole at set intervals from the cut-in point towards the guide roadway to the selected delamination layer; When the construction reaches the distance set by the advance cut-in point, start mining the working face; The mining of the working face is carried out simultaneously with the construction of the cross-layer boreholes; S6: Use the gas extraction well to extract gas; S7: Carry out the next working face in the same way, and repeat the cycle.

[0005] Preferably, in step S1, the receiving guide roadway is located in the designed receiving roadway, and its cross-sectional dimensions are smaller than those of the receiving roadway.

[0006] Preferably, in step S2, an air door is arranged outside the first auxiliary level roadway and outside the second auxiliary level roadway in the receiving guide roadway.

[0007] Preferably, in step S2, the cross-sectional dimensions of the first auxiliary level roadway and the second auxiliary level roadway are smaller than those of the return air level roadway and the transport level roadway.

[0008] Preferably, in step S2, an air door is arranged in the first auxiliary level tunnel and the second auxiliary level tunnel near the receiving guide tunnel.

[0009] Preferably, in step S3, the boreholes drilled from the first auxiliary tunnel and the second auxiliary tunnel are arranged alternately.

[0010] Preferably, in step S3, the key layer directly above the selected delamination layer does not break during the entire mining process of the working face.

[0011] Preferably, in step S3, the gas extraction well is a set distance from the cut-off point and is within the plane range of the separation layer.

[0012] Preferably, in step S5, as the working face is mined, the selected separation layer is formed. The gas drainage well is connected to the coal seam in the working face and the goaf formed by coal seam mining through separation and cross-layer boreholes. The coal seam is pre-drained based on the cross-layer boreholes already constructed at the advanced working face mining location. The coal seam is mined during mining based on the cross-layer boreholes already constructed at the working face mining location. The goaf is mined after mining based on the cross-layer boreholes within the goaf formed by the working face mining.

[0013] Preferably, in step S6, section coal pillars are set between working faces.

[0014] The inventive points and beneficial technical effects of this invention are as follows: 1. This invention proposes a deep coal seam mining method that combines hydraulic fracturing and pressure relief with cross-layer drilling and extraction. It utilizes the delamination generated during coal seam mining as a channel for gas migration to replace the traditional high-pressure extraction roadway. Cross-layer drilling is used to connect the coal seam and the delamination, and then gas extraction wells are constructed from the surface to connect the delamination. This allows for the extraction of gas separated before and after coal seam mining from the surface. While ensuring the gas control effect, this method greatly reduces the amount of engineering work and facilitates the selection of gas extraction equipment.

[0015] 2. This invention creatively proposes to construct an auxiliary level roadway in an O-ring and to construct cross-layer boreholes in the auxiliary level roadway, thereby facilitating the extraction of gas generated during working face mining, facilitating the construction of cross-layer boreholes, and reducing the interference of cross-layer borehole construction on normal coal mining operations.

[0016] 3. Since the development range of the delamination layer is roughly the same as the mining range of the working face, the gas drainage method in this invention can drain gas from the entire mining range of the working face, and only one gas drainage well needs to be constructed. The location of the gas drainage well is convenient, and it can be located as close as possible to the cut-off while ensuring the connection of the delamination layer. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the plan layout of the deep coal seam mining method of the present invention.

[0018] Figure 2 This is a schematic diagram of the cross-sectional layout of the deep coal seam mining method of the present invention. Figure 1 (AA).

[0019] In the diagram: 1-Return air uphill; 2-Transport uphill; 3-Return air level roadway; 4-First auxiliary level roadway; 5-Transport level roadway; 6-Second auxiliary level roadway; 7-Cut-off; 8-Guide roadway; 9-Gas extraction well; 10-In-seam borehole; 11-Sediment; 12-Separation layer; 13-Coal seam; 14-Inter-seam borehole; 15-Air door. Detailed Implementation

[0020] The specific embodiments of the present invention will now be described in conjunction with the accompanying drawings.

[0021] like Figures 1-2 As shown, this invention proposes a method for deep coal seam mining that combines hydraulic fracturing and pressure relief with cross-seam drilling extraction, comprising the following steps.

[0022] S1: Construct a return air level 3 along the strike from the return air incline 1, and construct a transport level 5 along the strike from the transport incline 2; construct a cut-in 7 at the starting point of mining to connect the return air level 3 and the transport level 5; construct a guide roadway 8 at the stopping point of mining to connect the return air level 3 and the transport level 5. The guide roadway 8 is located in the designed closing roadway, but its cross-sectional dimensions are smaller than the closing roadway. In this invention, strike refers to the strike of coal seam 13.

[0023] S2: The expected range of the O-ring after the working face is mined. The O-ring is a concept proposed in the mining field to guide gas drainage. It refers to the area around the goaf formed after the working face is mined, where fractures are relatively developed. It often serves as a channel for gas migration, which is beneficial for gas drainage. Its meaning is well-known in the field and will not be elaborated here. Within the expected O-ring, a first auxiliary passageway 4 is constructed along the strike on the side of the return airway 3 to connect the cut-off point 7 and the guide passageway 8. A second auxiliary passageway 6 is constructed along the strike on the side of the transport passageway 5 to connect the cut-off point 7 and the guide passageway 8. In the guide passageway 8, an air door 15 is arranged outside the first auxiliary passageway 4 and outside the second auxiliary passageway 6. The cross-sectional dimensions of the first auxiliary passageway 4 and the second auxiliary passageway 6 are smaller than those of the return airway 3 and the transport passageway 5. Preferably, an air door 15 (not shown in the figure) is also arranged near the guide passageway 8 in the first auxiliary passageway 4 and the second auxiliary passageway 6.

[0024] S3: The first auxiliary level roadway 4 and the second auxiliary level roadway 6 are used to construct in-seam boreholes 10 in the working face. The in-seam boreholes 10 are used to perform hydraulic fracturing on the coal seam 13 to relieve the pressure on the coal seam 13. Then, the in-seam boreholes 10 are used to perform gas pre-extraction on the coal seam 13 in the working face. The in-seam boreholes 10 constructed from the first auxiliary level roadway 4 and the second auxiliary level roadway 6 are arranged alternately.

[0025] At the same time, based on the characteristics of the stratum 11, the location of the delamination 12 in the curved subsidence zone is determined, and the delamination 12 that is close to the water-conducting fracture zone is selected as the gas migration plane channel. The key layer directly above the selected delamination 12 is not broken during the entire mining process of the working face. A gas extraction well 9 is constructed from the ground to the selected delamination 12 within a certain distance from the cut-out 7 and within the plane range of the delamination 12.

[0026] S4: In the first auxiliary level roadway 4 and the second auxiliary level roadway 6, starting from the cut-in 7, construct a cross-layer borehole 14 at predetermined intervals towards the receiving guide roadway 8 until the selected separation layer 12; after construction reaches the predetermined distance ahead of the cut-in 7, which is 30~50m in this embodiment, start mining the working face, and the mining width range is the coal seam 13 between the transport level roadway 5 and the return air level roadway 3; the mining of the working face and the construction of the cross-layer borehole 14 are carried out simultaneously, and the construction of the cross-layer borehole 14 is always ahead of the aforementioned predetermined distance of the mining position.

[0027] S5: As the working face is mined, the selected separation layer 12 is formed in the stratum 11. The gas drainage well 9 connects the coal seam 13 in the working face and the goaf formed by the mining of the coal seam 13 through the separation layer 12 and the cross-layer borehole 14. It can carry out gas drainage in the working face range of the cross-layer borehole 14 that has been constructed. Specifically, it can carry out advance drainage of the coal seam 13 based on the cross-layer borehole 14 constructed at the advanced working face mining position, carry out mining drainage at the mining location of the coal seam 13 based on the cross-layer borehole 14 constructed at the working face mining position, and carry out gas drainage in the goaf area based on the cross-layer borehole 14 within the range of the goaf formed by the working face mining, that is, post-mining drainage, so as to carry out gas drainage and prevention throughout the entire mining process of the coal seam 13 in the working face.

[0028] S6: After the working face is mined out, a section coal pillar is set up between the working face and the next working face, and the next working face is mined in the same way, and so on.

[0029] This invention is not limited to the preferred embodiments described above. Anyone can derive other methods in various forms under the guidance of this invention. Any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for deep coal seam mining that combines hydraulic fracturing and pressure relief with cross-seam drilling and extraction, characterized in that, Includes the following steps: S1: Construct the return airway and transport airway and connect them with a cut-in; construct a guide roadway at the stop mining position of the working face to connect the return airway and transport airway; the guide roadway is located in the designed exit roadway and its cross-sectional dimensions are smaller than the exit roadway. S2: Within the expected O-ring range, construct the first auxiliary level along the strike on the side of the return air level to connect the cut-off point and the exit guide level; construct the second auxiliary level along the strike on the side of the transport level to connect the cut-off point and the exit guide level; in the exit guide level, arrange an air door outside the first auxiliary level and outside the second auxiliary level respectively; the cross-sectional dimensions of the first auxiliary level and the second auxiliary level are smaller than those of the return air level and the transport level. S3: Drill in-seam boreholes in the working face from the first and second auxiliary horizontal roadways. Use the in-seam boreholes to hydraulically fracture the coal seam to relieve pressure on the coal seam. Then use the in-seam boreholes to pre-extract gas from the coal seam in the working face. At the same time, select the delamination zone that is close to the water-conducting fracture zone as the gas migration plane channel and construct gas extraction wells from the ground to the selected delamination zone. S4: In the first and second auxiliary level roadways, starting from the pre-cutting eye, construct a cross-layer borehole at set intervals towards the guide roadway until the selected separation layer; after constructing to the set distance of the pre-cutting eye, start mining the working face; the mining of the working face is carried out simultaneously with the construction of the cross-layer borehole. S5: Gas extraction using gas extraction wells; S6: Perform the next working face mining in the same way, and repeat the cycle.

2. The deep coal seam mining method according to claim 1, which combines hydraulic fracturing and pressure relief with cross-layer drilling and extraction, is characterized in that... In step S2, an air door is installed in the first auxiliary level tunnel and the second auxiliary level tunnel near the receiving guide tunnel.

3. The deep coal seam mining method according to claim 1, which combines hydraulic fracturing and pressure relief with cross-layer drilling and extraction, is characterized in that... In step S3, the boreholes drilled from the first auxiliary tunnel and the second auxiliary tunnel are arranged alternately.

4. The deep coal seam mining method according to claim 1, which combines hydraulic fracturing and pressure relief with cross-layer drilling and extraction, is characterized in that... In step S3, the key layer directly above the selected delamination layer is not broken during the entire mining process of the working face.

5. The deep coal seam mining method according to claim 1, which combines hydraulic fracturing and pressure relief with cross-layer drilling and extraction, is characterized in that... In step S3, the gas extraction well is located at a set distance from the cut-off point and within the plane range of the separation layer.

6. The deep coal seam mining method according to claim 1, which combines hydraulic fracturing and pressure relief with cross-layer drilling and extraction, is characterized in that... In step S5, as the working face is mined, the selected separation layer is formed. The gas drainage well is connected to the coal seam in the working face and the goaf formed by coal seam mining through separation and cross-layer boreholes. Based on the cross-layer boreholes already constructed at the advanced working face mining location, the coal seam is pre-drained. Based on the cross-layer boreholes already constructed at the working face mining location, the coal seam is mined and drained during mining. Based on the cross-layer boreholes within the goaf formed by the working face mining, the goaf is drained after mining.

7. The deep coal seam mining method according to claim 1, which combines hydraulic fracturing and pressure relief with cross-layer drilling and extraction, is characterized in that... In step S6, section coal pillars are set between working faces.

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