Coal seam drilling extraction and pressure relief integrated treatment method based on flexible hole sealing material

Abstract

The invention discloses a flexible hole sealing material-based coal seam drilling extraction and pressure relief integrated treatment method, which comprises the following steps of: constructing a gas extraction drilling hole in a coal seam roadway under a coal mine, constructing a pressure relief drilling hole on the basis, connecting a hole sealing device, an extraction pipe and a grouting pipe, and feeding a connected pipeline into a hole sealing section of the drilling hole; preparing a flexible hole sealing material and sealing the drilled hole by using the flexible hole sealing material; an extraction pipe is connected with a negative pressure pipeline, and drilling gas is extracted; construction of all the drill holes is completed according to the drill hole spacing of the gas extraction drill holes; and monitoring the hole sealing quality, and performing secondary sealing on the drill hole by using a flexible hole sealing material when air leakage of the drill hole is found. The method has the beneficial effects that the problem of space and time conflict between the pressure relief drill hole and the gas extraction drill hole of the coal seam of the rock burst and high gas mine is solved, the purpose of integrated treatment of extraction and pressure relief of the drill hole of the coal seam is achieved, and manpower, material resources and time cost can be saved.

Description

Technical Field

[0001] This invention belongs to the field of mine gas extraction technology and relates to an integrated treatment method for coal seam drilling extraction and pressure relief based on flexible sealing materials. Background Technology

[0002] Under the current circumstances, major coal production bases are gradually shifting to large-scale production bases in western regions such as Shanxi, Shaanxi, Inner Mongolia, and Xinjiang. Mines in western mining areas generally exhibit characteristics of complex disasters such as rock bursts and high gas levels. To ensure safe and efficient coal mining, gas control and mine pressure control have always been key issues of great concern to coal mining enterprises. Currently, coal mining enterprises typically use gas drainage boreholes within the coal seam to prevent gas disasters and large-diameter pressure relief boreholes within the coal seam to reduce coal stress and prevent rockburst disasters. However, gas drainage boreholes and pressure relief boreholes are spatially mutually restrictive: after the pressure relief borehole is formed, the surrounding rock stress redistributes. When the distance between the pressure relief borehole and the gas drainage borehole is too small, and the drainage borehole is located within the pressure relief influence range of the pressure relief borehole, the drainage borehole is prone to deformation and blockage. At the same time, the cracks in the sealing section of the drainage borehole further expand, reducing the borehole sealing quality and thus affecting the overall gas drainage effect. On the other hand, there is also a time conflict between gas drainage boreholes and pressure relief boreholes: pressure relief boreholes need to be implemented before the surrounding rock stress concentrates to relieve pressure in advance; gas drainage boreholes need to ensure sufficient drainage time to effectively reduce the gas content. If the construction sequence is unreasonable, situations may occur such as "the drainage borehole fails during pressure relief" or "the surrounding rock becomes unstable before drainage is completed." Summary of the Invention

[0003] The purpose of this invention is to provide an integrated method for coal seam drilling extraction and depressurization based on flexible sealing materials, which solves the problem of spatial and temporal conflicts between gas extraction boreholes and depressurization boreholes in high-gas and rockburst mines.

[0004] The technical solution adopted in this invention is an integrated treatment method for coal seam drilling extraction and pressure relief based on flexible sealing materials, comprising the following steps: S1. Constructing gas extraction boreholes in underground coal seam roadways of coal mines; S2. Construct pressure relief boreholes based on gas extraction boreholes; S3. Connect the sealing device, extraction pipe and grouting pipe, and send the connected extraction pipe, sealing device and grouting pipe into the sealing section of the borehole; S4. Prepare flexible sealing material and use the flexible sealing material to seal the borehole; S5. Connect the extraction pipe to the negative pressure pipeline to extract borehole gas; S6. Repeat S1-S5 according to the drilling spacing of the gas drainage boreholes to complete the drilling of all boreholes. S7. Monitor the sealing quality. If air leakage is found in the borehole, use flexible sealing material to seal the borehole a second time.

[0005] The invention is further characterized in that: the diameter of the gas extraction borehole of S1 is 90mm~120mm, the borehole depth is not less than 150m, the initial sealing depth of the borehole is 5m~8m, and the sealing length of the borehole is 8m~15m.

[0006] The construction of the S2 pressure relief borehole involves enlarging the gas extraction borehole using a drill bit. The enlargement depth is the same as the pressure relief borehole depth, and the enlargement diameter is the same as the pressure relief borehole diameter. The pressure relief borehole depth is 15m~30m, and the pressure relief borehole diameter is 100mm~200mm.

[0007] The S3 sealing device includes a front sealing device and a rear sealing device. The connection between the S3 sealing device, extraction pipe and grouting pipe is to bond the front sealing device and rear sealing device to the extraction pipe with PVC quick-drying adhesive. The front sealing device and rear sealing device are connected to the grouting pipe with quick connectors and are fixed to the extraction pipe in sections with tape.

[0008] The initial sealing depth of the sealing section is 5m~8m, and the sealing length is 8m~15m; the length of the connecting pipe and the grouting pipe between the front sealing device and the rear sealing device is the same as the sealing length.

[0009] The specific steps of S4 are as follows: S4.1 Add environmentally friendly phase change gel and water to the grouting mixing tank. During the addition process, use a pneumatic agitator to stir the slurry for 3 to 6 minutes. After stirring, the slurry is a uniformly mixed slurry. S4.2 Use a grouting pump to inject the prepared flexible sealing material into the front and rear sealing devices through the grouting pipe. After the burst valve is opened, continue to inject the prepared flexible sealing material into the middle area between the front and rear sealing devices. When the grouting pressure reaches 0.5MPa-1.0MPa three times, stop grouting and bend and tie the grouting pipe 10cm away from the hole opening.

[0010] The weight ratio of S4.1's environmentally friendly phase change gel to water is: environmentally friendly phase change gel: water = 2~4:100.

[0011] The borehole spacing for gas extraction boreholes in S6 is 1m-3m.

[0012] The S7 monitors the sealing quality by releasing tracer gas into the borehole at the initial sealing depth and measuring the concentration of tracer gas in the extraction pipe. When tracer gas is detected in the extraction pipe, it indicates borehole leakage.

[0013] S7 uses flexible sealing material to perform secondary sealing of the borehole to start the backup grouting pipe. The prepared flexible sealing material is injected into the sealing section. When the grouting pressure reaches 1.0MPa-1.5MPa three times, the grouting is stopped, and the backup grouting pipe is bent and tied.

[0014] The beneficial effects of this invention are: 1. This method resolves the spatial and temporal conflicts between pressure relief boreholes and gas extraction boreholes in coal seams in mines prone to rock bursts and high-gas mines, achieving integrated treatment of coal seam extraction and pressure relief, which can save significant manpower, material resources, and time costs.

[0015] 2. Compared to the most widely used cement-based and other consolidated borehole sealing materials, flexible sealing materials can adapt to borehole deformation without hindering it, exhibiting "pressure relief and force reduction" characteristics. This ensures effective gas extraction while simultaneously relieving pressure and mitigating hazards in the borehole sealing section. Furthermore, using flexible sealing materials for secondary grouting and sealing can guarantee long-term borehole extraction performance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the gas extraction borehole construction of the present invention; Figure 2 This is a schematic diagram of the construction of a pressure relief borehole based on the gas extraction borehole of this invention; Figure 3 This is a schematic diagram of the borehole sealing construction of the present invention; Figure 4 This is a schematic diagram of the drilling pressure relief of the present invention; Figure 5 This is a top view diagram showing the completed drilling operation of the present invention.

[0017] In the diagram, 1. Gas extraction borehole, 2. Borehole pressure relief section, 2-1. Adaptive deformation pressure relief section, 2-2. Hole pressure relief section, 3. Extraction pipe, 4. Front-end sealing device, 5. Sealing section. Detailed Implementation

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

[0019] The purpose of this invention is to overcome the spatial and temporal conflict between gas drainage boreholes and pressure relief boreholes in high-gas and rockburst mines, and to provide an integrated treatment method for gas drainage and pressure relief in coal seams based on flexible sealing materials. The specific technical solution is as follows: First, the main borehole structure that meets the basic requirements for gas extraction is constructed. Then, through a staged borehole enlargement process, specific sections adapted to the pressure relief requirements are formed on the basis of the original borehole, achieving a precise division of the "extraction function section" and "pressure relief function section" within the same borehole. Subsequently, the extraction pipe is lowered, and the enlarged section is sealed with flexible sealing material and a suitable "two-plug-one-injection" sealing process. Utilizing the characteristics of flexible material, the sealing section can not only ensure the sealing of gas extraction, but also achieve pressure relief with the deformation of the borehole, thus simultaneously achieving the functions of extraction and pressure relief.

[0020] Connect the extraction pipe to the negative pressure pipeline to start the gas extraction operation; at the same time, use mine pressure monitoring methods to observe the pressure relief status of the surrounding rock in the borehole in real time, and monitor the gas extraction effect by monitoring the extraction concentration and flow rate.

[0021] Based on real-time monitoring data, when it is found that the gas extraction effect decreases after borehole pressure relief, the "secondary grouting" compensation function of flexible sealing material is used to reinforce and seal the sealing section, repair potential weak sealing areas, solve the problem of sealing quality decay in long-term treatment, ensure the continuous and stable extraction and pressure relief effect of the borehole, and achieve full-cycle treatment of complex disasters.

[0022] Example 1 The integrated coal seam drilling and depressurization treatment method based on flexible sealing materials includes the following steps: S1. Constructing gas extraction boreholes in underground coal seam roadways of coal mines; S2. Construct pressure relief boreholes based on gas extraction boreholes; S3. Connect the sealing device, extraction pipe and grouting pipe, and send the connected extraction pipe, sealing device and grouting pipe into the sealing section of the borehole; S4. Prepare flexible sealing material and use the prepared flexible sealing material to seal the drill hole; S5. Connect the extraction pipe to the negative pressure pipeline to extract borehole gas; S6. Repeat S1-S5 according to the drilling spacing of the gas drainage boreholes to complete the drilling of all boreholes. S7. Monitor the sealing quality. If air leakage is found in the borehole, use flexible sealing material to seal the borehole a second time.

[0023] Example 2 The integrated coal seam drilling and depressurization treatment method based on flexible sealing materials includes the following steps: S1. Constructing gas extraction boreholes in underground coal seam roadways of coal mines; The parameters of the gas drainage borehole are designed according to GB 50471-2018 "Design Standard for Coal Mine Gas Drainage Engineering"; the borehole diameter is 90mm~120mm, the borehole depth is not less than 150m, the initial sealing depth is 5m~8m, and the sealing length is 8m~15m.

[0024] S2. Construct pressure relief boreholes based on gas extraction boreholes; S3. Connect the sealing device, extraction pipe and grouting pipe, and send the connected extraction pipe, sealing device and grouting pipe into the sealing section of the borehole; S4. Prepare flexible sealing material and use the prepared flexible sealing material to seal the drill hole; S5. Connect the extraction pipe to the negative pressure pipeline to extract borehole gas; S6. Repeat S1-S5 according to the drilling spacing of the gas drainage boreholes to complete the drilling of all boreholes. S7. Monitor the sealing quality. If air leakage is found in the borehole, use flexible sealing material to seal the borehole a second time.

[0025] Example 3 The integrated coal seam drilling and depressurization treatment method based on flexible sealing materials includes the following steps: S1. Constructing gas extraction boreholes in underground coal seam roadways of coal mines; The parameters of the gas drainage borehole are designed according to GB 50471-2018 "Design Standard for Coal Mine Gas Drainage Engineering"; the borehole diameter is 90mm~120mm, the borehole depth is not less than 150m, the initial sealing depth is 5m~8m, and the sealing length is 8m~15m.

[0026] S2. Construct pressure relief boreholes based on gas extraction boreholes; The parameters of the pressure relief borehole were designed according to GB / T 25217.10-2019 "Methods for Measurement, Monitoring and Prevention of Rockburst Part 10: Methods for Pressure Relief and Prevention of Coal Seam Boreholes"; The construction of pressure relief boreholes involves using a drill bit to enlarge the gas extraction borehole. The enlargement depth is the same as the original drilling depth of the pressure relief borehole, and the enlargement diameter is the same as the original drilling diameter of the pressure relief borehole. The drilling depth of the pressure relief borehole is 15m to 30m, and the drilling diameter is 100mm to 200mm.

[0027] S3. Connect the sealing device, extraction pipe and grouting pipe, and send the connected extraction pipe, sealing device and grouting pipe into the sealing section of the borehole; S4. Prepare flexible sealing material and use the prepared flexible sealing material to seal the drill hole; S5. Connect the extraction pipe to the negative pressure pipeline to extract borehole gas; S6. Repeat S1-S5 according to the drilling spacing of the gas drainage boreholes to complete the drilling of all boreholes. S7. Monitor the sealing quality. If air leakage is found in the borehole, use flexible sealing material to seal the borehole a second time.

[0028] Example 4 The integrated coal seam drilling and depressurization treatment method based on flexible sealing materials includes the following steps: S1. Constructing gas extraction boreholes in underground coal seam roadways of coal mines; The parameters of the gas drainage borehole are designed according to GB 50471-2018 "Design Standard for Coal Mine Gas Drainage Engineering"; the borehole diameter is 90mm~120mm, the borehole depth is not less than 150m, the initial sealing depth is 5m~8m, and the sealing length is 8m~15m.

[0029] S2. Construct pressure relief boreholes based on gas extraction boreholes; The parameters of the pressure relief borehole were designed according to GB / T 25217.10-2019 "Methods for Measurement, Monitoring and Prevention of Rockburst Part 10: Methods for Pressure Relief and Prevention of Coal Seam Boreholes"; The construction of pressure relief boreholes involves using a drill bit to enlarge the gas extraction borehole. The enlargement depth is the same as the original drilling depth of the pressure relief borehole, and the enlargement diameter is the same as the original drilling diameter of the pressure relief borehole. The drilling depth of the pressure relief borehole is 15m to 30m, and the drilling diameter is 100mm to 200mm.

[0030] S3. Connect the sealing device, extraction pipe and grouting pipe, and send the connected extraction pipe, sealing device and grouting pipe into the sealing section of the borehole; The sealing device includes a front sealing device and a rear sealing device. The front sealing device and the rear sealing device are bonded to the extraction pipe using PVC quick-drying adhesive. The front sealing device and the rear sealing device are connected to the grouting pipe using quick connectors, and are fixed to the extraction pipe in sections using tape.

[0031] The initial sealing depth of the sealing section is 5m~8m, and the sealing length is 8m~15m; the length of the connecting pipe and the grouting pipe between the front sealing device and the rear sealing device is the same as the sealing length.

[0032] S4. Prepare flexible sealing material and use the prepared flexible sealing material to seal the drill hole; S5. Connect the extraction pipe to the negative pressure pipeline to extract borehole gas; S6. Repeat S1-S5 according to the drilling spacing of the gas drainage boreholes to complete the drilling of all boreholes. S7. Monitor the sealing quality. If air leakage is found in the borehole, use flexible sealing material to seal the borehole a second time.

[0033] Example 5 The integrated coal seam drilling and depressurization treatment method based on flexible sealing materials includes the following steps: S1. Constructing gas extraction boreholes in underground coal seam roadways of coal mines; The parameters of the gas drainage borehole are designed according to GB 50471-2018 "Design Standard for Coal Mine Gas Drainage Engineering"; the borehole diameter is 90mm~120mm, the borehole depth is not less than 150m, the initial sealing depth is 5m~8m, and the sealing length is 8m~15m.

[0034] S2. Construct pressure relief boreholes based on gas extraction boreholes; The parameters of the pressure relief borehole were designed according to GB / T 25217.10-2019 "Methods for Measurement, Monitoring and Prevention of Rockburst Part 10: Methods for Pressure Relief and Prevention of Coal Seam Boreholes"; The construction of pressure relief boreholes involves using a drill bit to enlarge the gas extraction borehole. The enlargement depth is the same as the original drilling depth of the pressure relief borehole, and the enlargement diameter is the same as the original drilling diameter of the pressure relief borehole. The drilling depth of the pressure relief borehole is 15m to 30m, and the drilling diameter is 100mm to 200mm.

[0035] S3. Connect the sealing device, extraction pipe and grouting pipe, and send the connected extraction pipe, sealing device and grouting pipe into the sealing section of the borehole; The sealing device includes a front sealing device and a rear sealing device. The front sealing device and the rear sealing device are bonded to the extraction pipe using PVC quick-drying adhesive. The front sealing device and the rear sealing device are connected to the grouting pipe using quick connectors, and are fixed to the extraction pipe in sections using tape.

[0036] The initial sealing depth of the sealing section is 5m~8m, and the sealing length is 8m~15m; the length of the connecting pipe and the grouting pipe between the front sealing device and the rear sealing device is the same as the sealing length.

[0037] S4. Prepare flexible sealing material and use the prepared flexible sealing material to seal the drill hole; S4.1 Add environmentally friendly phase change gel and water to the grouting mixing tank. During the addition process, use a pneumatic agitator to stir the slurry for 3 to 6 minutes. After stirring, the slurry is a uniformly mixed slurry.

[0038] S4.2 Use a grouting pump to inject the prepared flexible sealing material into the front and rear sealing devices through the grouting pipe. After the burst valve is opened, continue to inject the prepared flexible sealing material into the middle area between the front and rear sealing devices. When the grouting pressure reaches 0.5MPa-1.0MPa three times, stop grouting and bend and tie the grouting pipe 10cm away from the hole opening.

[0039] The weight ratio of environmentally friendly phase change gel to water is: environmentally friendly phase change gel: water = 2~4:100.

[0040] The environmentally friendly phase change gel is composed of a base material and a modifier. The base material consists of cellulose ether, superabsorbent resin, glyoxal, and sodium pyrrolidone carboxylate. The modifier consists of preservatives, fungicides, and reinforcing agents. The weight ratio of the base material to the modifier is 1-4:0.2-0.5; The base material is composed of 80-90 parts by weight of cellulose ether, 5-10 parts by weight of superabsorbent resin, 1-10 parts by weight of glyoxal and 1-5 parts by weight of sodium pyrrolidone carboxylate; the cellulose ether is a composite cellulose ether, specifically composed of 50-80 parts by weight of hydroxypropyl methylcellulose, 10-30 parts by weight of polyanionic cellulose and 20-40 parts by weight of hydroxyethyl cellulose. The modifier consists of 20-30 parts by weight of preservative, 30-40 parts by weight of mildew inhibitor, and 30-50 parts by weight of reinforcing agent; the reinforcing agent consists of 30-50 parts by weight of calcium carbonate, 30-40 parts by weight of calcium sulfate, 10-20 parts by weight of calcium bicarbonate, and 10-20 parts by weight of calcium hydroxide; the preservative consists of 10-30 parts by weight of potassium sorbate, 50-70 parts by weight of calcium propionate, and 10-20 parts by weight of D The product is composed of sodium isoascorbate; the antifungal agent is composed of 50-70 parts by weight of calcium benzoate and 30-50 parts by weight of dehydroacetic acid.

[0041] The prepared flexible sealing material has the following characteristics: (1) Viscosity before gel point: <70 cP, final viscosity: >200000 cP; (2) Gelation time: 80~180min; The sealing principle of flexible sealing materials: The high molecular weight polymers contained in environmentally friendly phase change gels can form hydrogen bonds with water molecules, turning free water into bound water and giving the material a certain water retention capacity. At the same time, the network structure formed by hydrogen bonds enables the EPCG material to gel, achieving the purpose of borehole sealing.

[0042] S5. Connect the extraction pipe to the negative pressure pipeline to extract borehole gas; S6. Repeat S1-S5 according to the drilling spacing of the gas drainage boreholes to complete the drilling of all boreholes. S7. Monitor the sealing quality. If air leakage is found in the borehole, use flexible sealing material to seal the borehole a second time.

[0043] Example 6 The integrated coal seam drilling and depressurization treatment method based on flexible sealing materials includes the following steps: S1. Constructing gas extraction boreholes in underground coal seam roadways of coal mines; The parameters of the gas drainage borehole are designed according to GB 50471-2018 "Design Standard for Coal Mine Gas Drainage Engineering"; the borehole diameter is 90mm~120mm, the borehole depth is not less than 150m, the initial sealing depth is 5m~8m, and the sealing length is 8m~15m.

[0044] S2. Construct pressure relief boreholes based on gas extraction boreholes; The parameters of the pressure relief borehole were designed according to GB / T 25217.10-2019 "Methods for Measurement, Monitoring and Prevention of Rockburst Part 10: Methods for Pressure Relief and Prevention of Coal Seam Boreholes"; The construction of pressure relief boreholes involves using a drill bit to enlarge the gas extraction borehole. The enlargement depth is the same as the original drilling depth of the pressure relief borehole, and the enlargement diameter is the same as the original drilling diameter of the pressure relief borehole. The drilling depth of the pressure relief borehole is 15m to 30m, and the drilling diameter is 100mm to 200mm.

[0045] S3. Connect the sealing device, extraction pipe and grouting pipe, and send the connected extraction pipe, sealing device and grouting pipe into the sealing section of the borehole; The sealing device includes a front sealing device and a rear sealing device. The front sealing device and the rear sealing device are bonded to the extraction pipe using PVC quick-drying adhesive. The front sealing device and the rear sealing device are connected to the grouting pipe using quick connectors, and are fixed to the extraction pipe in sections using tape.

[0046] The initial sealing depth of the sealing section is 5m~8m, and the sealing length is 8m~15m; the length of the connecting pipe and the grouting pipe between the front sealing device and the rear sealing device is the same as the sealing length.

[0047] S4. Prepare flexible sealing material and use the prepared flexible sealing material to seal the drill hole; S4.1 Add environmentally friendly phase change gel and water to the grouting mixing tank. During the addition process, use a pneumatic agitator to stir the slurry for 3 to 6 minutes. After stirring, the slurry is a uniformly mixed slurry.

[0048] S4.2 Use a grouting pump to inject the prepared flexible sealing material into the front and rear sealing devices through the grouting pipe. After the burst valve is opened, continue to inject the prepared flexible sealing material into the middle area between the front and rear sealing devices. When the grouting pressure reaches 0.5MPa-1.0MPa three times, stop grouting and bend and tie the grouting pipe 10cm away from the hole opening.

[0049] The weight ratio of environmentally friendly phase change gel to water is: environmentally friendly phase change gel: water = 2~4:100.

[0050] The environmentally friendly phase change gel is composed of a base material and a modifier. The base material consists of cellulose ether, superabsorbent resin, glyoxal, and sodium pyrrolidone carboxylate. The modifier consists of preservatives, fungicides, and reinforcing agents. The weight ratio of the base material to the modifier is 1-4:0.2-0.5; The base material is composed of 80-90 parts by weight of cellulose ether, 5-10 parts by weight of superabsorbent resin, 1-10 parts by weight of glyoxal and 1-5 parts by weight of sodium pyrrolidone carboxylate; the cellulose ether is a composite cellulose ether, specifically composed of 50-80 parts by weight of hydroxypropyl methylcellulose, 10-30 parts by weight of polyanionic cellulose and 20-40 parts by weight of hydroxyethyl cellulose. The modifier consists of 20-30 parts by weight of preservative, 30-40 parts by weight of mildew inhibitor, and 30-50 parts by weight of reinforcing agent; the reinforcing agent consists of 30-50 parts by weight of calcium carbonate, 30-40 parts by weight of calcium sulfate, 10-20 parts by weight of calcium bicarbonate, and 10-20 parts by weight of calcium hydroxide; the preservative consists of 10-30 parts by weight of potassium sorbate, 50-70 parts by weight of calcium propionate, and 10-20 parts by weight of D The product is composed of sodium isoascorbate; the antifungal agent is composed of 50-70 parts by weight of calcium benzoate and 30-50 parts by weight of dehydroacetic acid.

[0051] The prepared flexible sealing material has the following characteristics: (1) Viscosity before gel point: <70 cP, final viscosity: >200000 cP; (2) Gelation time: 80~180min; The sealing principle of flexible sealing materials: The high molecular weight polymers contained in environmentally friendly phase change gels can form hydrogen bonds with water molecules, turning free water into bound water and giving the material a certain water retention capacity. At the same time, the network structure formed by hydrogen bonds enables the EPCG material to gel, achieving the purpose of borehole sealing.

[0052] S5. Connect the extraction pipe to the negative pressure pipeline to extract borehole gas; S6. Repeat S1-S5 according to the drilling spacing of 1m-3m for gas drainage boreholes to complete all drilling construction. S7. Monitor the sealing quality. If air leakage is found in the borehole, use flexible sealing material to seal the borehole a second time.

[0053] The quality of the sealing is determined by releasing tracer gas into the borehole at the initial sealing depth and measuring the concentration of tracer gas in the extraction pipe. When tracer gas is detected in the extraction pipe, it indicates that the borehole is leaking.

[0054] To activate the backup grouting pipe, a secondary seal is applied to the borehole using flexible sealing material. The prepared flexible sealing material is injected into the sealing section. When the grouting pressure reaches 1.0MPa-1.5MPa three times, grouting is stopped, and the backup grouting pipe is bent and tied.

[0055] Example 7 The method of this invention is specifically applied in the drilling construction of a certain coal seam: (1) Design the parameters of gas drainage borehole 1 according to GB 50471-2018 "Design Standard for Coal Mine Gas Drainage Engineering" and design the parameters of pressure relief borehole according to GB / T25217.10-2019 "Methods for Measurement, Monitoring and Prevention of Rockburst Part 10: Methods for Pressure Relief and Prevention of Coal Seam Boreholes"; The borehole spacing of gas extraction borehole 1 is 2m, the borehole diameter is 113mm, the borehole depth is 180m, the initial sealing depth is 5m, and the sealing length is 12m.

[0056] The drilling spacing for the pressure relief boreholes is 2m, the borehole diameter is 173mm, and the drilling depth is 20m. (2) For example Figure 1 As shown, move the drilling rig to the target location, use a 113mm drill bit, and construct the gas drainage borehole 1 vertically through the coal face to the designed depth of 180m.

[0057] (3) such as Figure 2 As shown, the 113mm diameter drill bit is removed and replaced with a 153mm diameter drill bit. The hole is enlarged to a pressure relief drilling depth of 20m based on the original hole, completing the first enlargement. The 153mm diameter drill bit is removed and replaced with a 173mm diameter drill bit, enlarging the hole to a pressure relief drilling depth of 20m to complete the second enlargement, thus completing the construction of the pressure relief section 2.

[0058] (4) Bond the front end sealer 4 and the rear end sealer to the extraction pipe 3 with PVC quick-drying glue. Connect the front end sealer 4 and the rear end sealer to the grouting pipe with quick connectors and fix them to the extraction pipe 3 in sections with tape.

[0059] like Figure 3 As shown, the 173mm diameter drill bit is withdrawn, and the sealing device, extraction pipe 3, and grouting pipe are lowered into the borehole according to the designed initial sealing depth of 5m and sealing length of 12m. The borehole sealing construction is carried out in the enlarged section. Environmentally friendly phase change gel and water are used to prepare flexible sealing material. The preparation ratio is 3kg of environmentally friendly phase change gel per 100kg of water. The flexible sealing material is used to carry out the sealing construction using the "two plugs and one injection" drilling sealing process.

[0060] (5) Connect extraction pipe 3 to the negative pressure pipeline to extract borehole gas. Simultaneously, use mine pressure monitoring methods to observe the pressure relief of the surrounding rock in the borehole, and use borehole concentration and flow rate monitoring methods to observe the borehole extraction situation. For example... Figure 4 As shown, after the borehole is depressurized, the borehole deforms. The sealing section 5 utilizes the "adaptive borehole deformation" and "pressure relief" characteristics of the flexible sealing material to maximize the pressure relief effect.

[0061] (6) For example Figure 5 As shown, according to the gas extraction borehole spacing of 2m, repeat steps (2) to (5) until all boreholes are completed. The pressure relief section is divided into two parts: the empty hole pressure relief section 2-1 and the adaptive deformation pressure relief section 2-2.

[0062] (6) Continuously monitor the stress of the surrounding rock and the extraction parameters of the borehole. When the borehole leaks gas, continue to use environmentally friendly phase change gel and water to prepare flexible sealing material. The preparation ratio is 3 kg of environmentally friendly phase change gel per 100 kg of water. Inject the prepared flexible sealing material into the borehole sealing section using the spare grouting pipe to perform secondary grouting compensation and sealing of the borehole, thereby improving the gas extraction effect of the borehole.

Claims

1. A method for integrated coal seam drilling, extraction, and pressure relief based on flexible sealing materials, characterized in that, Includes the following steps: S1. Constructing gas extraction boreholes in underground coal seam roadways of coal mines; S2. Construct pressure relief boreholes based on gas extraction boreholes; S3. Connect the sealing device, extraction pipe and grouting pipe, and send the connected extraction pipe, sealing device and grouting pipe into the sealing section of the borehole; S4. Prepare flexible sealing material and use the flexible sealing material to seal the borehole; S5. Connect the extraction pipe to the negative pressure pipeline to extract borehole gas; S6. Repeat S1-S5 according to the drilling spacing of the gas drainage boreholes to complete the drilling of all boreholes. S7. Monitor the sealing quality. If air leakage is found in the borehole, use flexible sealing material to seal the borehole a second time.

2. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 1, characterized in that, The diameter of the gas extraction borehole described in S1 is 90mm~120mm, the borehole depth is not less than 150m, the initial sealing depth is 5m~8m, and the sealing length is 8m~15m.

3. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 1, characterized in that, The pressure relief drilling described in S2 involves enlarging the gas extraction drilling hole using a drill bit. The enlargement depth is the same as the pressure relief drilling depth, and the enlargement diameter is the same as the pressure relief drilling diameter. The pressure relief drilling depth is 15m to 30m, and the pressure relief drilling diameter is 100mm to 200mm.

4. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 1, characterized in that, The sealing device described in S3 includes a front sealing device and a rear sealing device; the connection between the sealing device, the extraction pipe and the grouting pipe in S3 is to bond the front sealing device, the rear sealing device and the extraction pipe with PVC quick-drying adhesive, and to connect the front sealing device, the rear sealing device and the grouting pipe with quick connectors, and to fix them to the extraction pipe in sections with tape.

5. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 4, characterized in that, The initial sealing depth of the sealing section is 5m~8m, and the sealing length is 8m~15m; the length of the connecting pipe and the grouting pipe between the front sealing device and the rear sealing device is the same as the sealing length.

6. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 1, characterized in that, The specific steps of S4 are as follows: S4.1 Add environmentally friendly phase change gel and water to the grouting mixing tank. During the addition process, use a pneumatic agitator to stir the slurry for 3 to 6 minutes. After stirring, the slurry is a uniformly mixed slurry. S4.2 Use a grouting pump to inject the prepared flexible sealing material into the front and rear sealing devices through the grouting pipe. After the burst valve is opened, continue to inject the prepared flexible sealing material into the middle area between the front and rear sealing devices. When the grouting pressure reaches 0.5MPa-1.0MPa three times, stop grouting and bend and tie the grouting pipe 10cm away from the hole opening.

7. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 6, characterized in that, The weight ratio of the environmentally friendly phase change gel and water described in S4.1 is: environmentally friendly phase change gel: water = 2~4:

100.

8. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 1, characterized in that, The borehole spacing of the gas extraction boreholes described in S6 is 1m-3m.

9. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 1, characterized in that, The monitoring of the sealing quality described in S7 involves releasing tracer gas into the borehole at the initial sealing depth and measuring the concentration of tracer gas in the extraction pipe to determine the sealing quality. When tracer gas is detected in the extraction pipe, it indicates that the borehole is leaking gas.

10. The integrated coal seam drilling and depressurization method based on flexible sealing materials according to claim 1, characterized in that, S7 describes the use of flexible sealing material to perform secondary sealing of the borehole. To start the backup grouting pipe, the flexible sealing material prepared by environmentally friendly phase change gel and water is injected into the sealing section. When the grouting pressure reaches 1.0 MPa or more three times, the grouting is stopped, and the backup grouting pipe is bent and tied.

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