Method for regulating and controlling sealing performance of drill hole in gas extraction process

Abstract

The invention discloses a method for regulating and controlling the sealing performance of a drill hole in the gas extraction process. The method comprises the following steps that a hole sealing and pressure supplementing device is installed on an extraction pipe and pushed into the drill hole from back to front; water is injected into the hole sealing and pressure supplementing device; grouting is conducted in the hole sealing and pressure supplementing device, and first-time hole sealing is completed; gas in the drill hole is extracted through the extraction pipe; in the gas extraction process, when it is detected that the gas extraction concentration is reduced, water injection and pressure supplementation are conducted; continuing gas extraction, and repeating the step of water injection and pressure supplementation if it is detected that the gas extraction concentration is reduced. The cost is reduced while the sealing effect is guaranteed, safety and reliability are achieved, grout injected in the grouting hole sealing process has better shrinkage resistance and lower permeability, and therefore the hole sealing section between the two bags can have the longer sealing effect; by monitoring the pressure, gas concentration and other parameters in the drill hole in real time, real-time liquid injection and pressure supplementation are conducted in the rubber pipe to enhance the sealing performance of the drill hole, and safe and efficient production of a mine is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of mining engineering, and particularly relates to a method for regulating the sealing of boreholes during gas drainage. Background Art

[0002] With the increase in the depth and intensity of coal mining, the gas content and emission amount in coal seams are becoming increasingly serious, and gas drainage has become an important means to ensure the safe production of coal mines. However, in the later stage of boreholes, the traditional hole sealing method often forms air leakage channels due to cracks around the borehole, resulting in a reduction in the gas drainage effect.

[0003] In the prior art, the sealing of gas drainage boreholes mostly adopts the method of "two plugs and one injection", that is, using a bladder and grouting material to form a sealing section. However, due to the influence of factors such as the negative pressure of borehole drainage and mining disturbance, cracks are likely to appear on the outer circumference of the borehole wall, resulting in air leakage, which in turn affects the gas drainage effect. To solve this problem, the present invention develops a method for regulating the sealing of boreholes during gas drainage on the basis of the traditional "two plugs and one injection" method, realizing continuous and effective sealing of boreholes during gas drainage and improving the gas drainage efficiency. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems existing in the prior art, the present invention provides a method for regulating the sealing of boreholes during gas drainage, which is convenient to operate, can be adjusted for hole sealing multiple times, has a good hole sealing effect and strong reliability.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: A method for regulating the sealing of boreholes during gas drainage, comprising the following steps: S1. Install the hole sealing and pressure compensating device on the drainage pipe and push it forward into the borehole from the back; S2. Inject water into the hole sealing and pressure compensating device. When the injection pressure is not less than the predetermined grouting hole sealing pressure P, stop injecting water; S3. Then inject grout into the hole sealing and pressure compensating device. When the grouting pressure reaches the grouting hole sealing pressure P, the first hole sealing is completed; S4. Drain the gas in the borehole through the drainage pipe; S5. During gas drainage, when it is detected that the gas drainage concentration decreases, inject water for pressure compensation into the hole sealing and pressure compensating device in the same manner as in step S2. When it is detected that the gas concentration increases and returns to the original state, stop injecting water for pressure compensation; S6. Continue gas drainage. If it is detected that the gas drainage concentration decreases, repeat step S5.

[0006] The hole - sealing and pressure - compensating device includes a front bladder and a rear bladder that are arranged at intervals before and after on the gas drainage pipe. A grouting pipe parallel to the gas drainage pipe is arranged between the front bladder and the rear bladder. The grouting pipe is provided with a front one - way valve located inside the front bladder, a rear one - way valve located inside the rear bladder, and a blasting valve located between the front bladder and the rear bladder. The gas drainage pipe is also provided with a radial expander located between the front bladder and the rear bladder, and a liquid injection pipeline passing through the rear bladder is connected to the rear end of the radial expander.

[0007] The radial expander includes a rubber tube coaxially arranged outside the gas drainage pipe. A rigid thin tube is fixedly arranged on the inner circle of the rubber tube. Central brackets sleeved on the gas drainage pipe are respectively arranged on the front - side inner circle and the rear - side inner circle of the rigid thin tube. The pipe wall of the rubber tube is a double - layer structure with a sealed cavity. A number of slurry - permeating holes that penetrate inside and outside in the radial direction are arranged on the rubber tube and the rigid thin tube. A liquid injection port connected to the front - end port of the liquid injection pipeline is arranged at the rear end of the rubber tube.

[0008] The central bracket includes a positioning ring sleeved on the gas drainage pipe. A jackscrew for pressing against the gas drainage pipe is threadedly connected to the positioning ring. Three support rods are evenly arranged along the circumferential direction on the outer circle of the positioning ring. The length of each support rod is along the radial direction of the positioning ring, and the outer end of the support rod is fixedly connected to the inner circle of the rigid thin tube.

[0009] The inlet end of the liquid injection pipeline is connected to a liquid storage tank. A liquid injection pump, a valve, and a pressure gauge are successively arranged on the liquid injection pipeline along the liquid flow direction.

[0010] The specific process of step S2 is as follows: Open the valve, start the liquid injection pump, inject clear water into the rubber tube through the liquid injection pipeline. The rubber tube expands by water injection inside, and the outer circle of the rubber tube is tightly pressed against the inner wall of the drill hole. When the injection pressure is not less than the predetermined grouting hole - sealing pressure P, close the liquid injection pump and the valve.

[0011] The specific process of step S3 is as follows: Inject slurry into the front bladder and the rear bladder through the grouting pipe. After the front bladder and the rear bladder are filled with slurry, continue to increase the grouting pressure. When the pressure reaches the blasting pressure P1 (such as 1.5 Mpa - 2 Mpa) of the blasting valve, the blasting valve opens, and the slurry is injected into the drill hole between the front bladder and the rear bladder. The slurry is injected into the cracks of the drill - hole wall through the slurry - permeating holes on the rubber tube. When the grouting pressure reaches the grouting hole - sealing pressure P, the first hole - sealing is completed.

[0012] The specific process of step S5 is as follows: During the gas drainage process, when it is detected that the gas drainage concentration decreases, open the valve on the liquid injection pipeline, start the liquid injection pump, and inject clear water into the rubber tube again. The rubber tube continues to expand, and the outer circle of the rubber tube further presses against and seals the inner wall of the drill hole. When the injection pressure reaches the set pressure - compensating hole - sealing pressure P2 and maintains for a period of time, and it is detected that the gas concentration rises and returns to the original state, close the liquid injection pump and the valve.

[0013] The described slurry is uniformly mixed by an environment-friendly hole-sealing material and water in a mass ratio of 1:1; The environment-friendly hole-sealing material is made by mixing raw materials with the following weight ratios: 700 - 800 parts of portland cement, 30 - 50 parts of superabsorbent resin, 30 - 50 parts of coal gangue powder, 30 - 50 parts of quick-setting agent, and 30 - 50 parts of expansive agent; the particle sizes of all raw materials are 80 - 200 mesh.

[0014] By weight percentage, the superabsorbent resin is composed of 75% sodium polyacrylate, 24% polyacrylic acid, 0.7% SiO2, and 0.3% Al2(SO4)3; The portland cement is 42.5-grade ordinary portland cement; The coal gangue powder is made by crushing the coal gangue generated during the coal mining process.

[0015] Adopting the above technical solution, compared with the prior art, the present invention has the following technical effects: (1) Improve the sealing effect: By setting a rubber tube between the front capsule and the rear capsule for dynamic supplementary pressure sealing, the air leakage phenomenon caused by cracks around the borehole can be effectively reduced, and the gas drainage efficiency can be improved.

[0016] (2) The positioning ring inside the radial expander is fixedly connected to the drainage pipe by a setscrew, so as to avoid the axial movement of the radial expander when installing it into the borehole.

[0017] (3) During use, first inject liquid into the rubber tube to make the rubber tube expand, so that the outer circle of the rubber tube is pressed against the inner wall of the borehole, and then grout. After grouting, the grout fills the inner circle space of the rubber tube, and at the same time supports the rigid thin tube, so that the rubber tube can only expand radially outward when expanding. At the same time, the grout is injected into the cracks on the inner wall of the borehole through the liquid-permeable holes on the rubber tube. Since the liquid injection pressure in the rubber tube is not less than the predetermined grouting hole-sealing pressure P, the grout will not cover the outer circle of the rubber tube. Even after the grout solidifies, the reliability of the rubber tube for re-supplementary pressure expansion can be ensured.

[0018] (4) The setting of the rigid thin tube facilitates the fixed connection with the support rod, ensures that the rubber tube remains in a stretched state when installing it into the borehole, and at the same time provides support for the expansion of the rubber tube, so that the rubber tube can only expand radially outward.

[0019] (5) Using gangue in the environmentally friendly hole - sealing material realizes the comprehensive utilization of industrial solid waste. Adding an expander to the environmentally friendly hole - sealing material enables expansion during solidification, avoiding the problem of cement shrinkage. It can actively support the borehole wall, prevent the formation of air - leakage channels due to shrinkage in the sealed section, and reduce the air - leakage volume during gas drainage. Adding superabsorbent resin to the environmentally friendly hole - sealing material can reduce the permeability of the hole - sealing material, enhance the sealing performance of the material, and improve the hole - sealing effect. The proportions of the various raw materials in the environmentally friendly hole - sealing material can also be adjusted to achieve more combination schemes.

[0020] In summary, the present invention reduces costs while ensuring the sealing effect, is safe and reliable. The grout injected during grouting hole - sealing has better anti - shrinkage properties and lower permeability, so that the sealed section between the two bladder bags has a longer - lasting sealing effect. By real - time monitoring parameters such as the pressure and gas concentration in the borehole and injecting liquid into the rubber tube in real - time for pressure compensation to enhance the sealing of the borehole, it ensures the safe and efficient production of the mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the overall structural schematic diagram of the hole - sealing pressure - compensation device in the present invention; Figure 2 is Figure 1 the end - face structural schematic diagram of the rubber expansion tube in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The following further describes the embodiments of the present invention in detail with reference to the drawings and embodiments.

[0023] As Figure 1 and Figure 2 shown, the method for regulating the sealing of boreholes during gas drainage of the present invention includes the following steps: S1. Install the hole - sealing pressure - compensation device on the extraction pipe 1 and push it forward into the borehole 21 from the rear; The hole - sealing pressure - compensation device includes a front bladder bag 2 and a rear bladder bag 3 arranged at intervals on the extraction pipe 1 from front to rear. A grouting pipe 4 parallel to the extraction pipe 1 is provided between the front bladder bag 2 and the rear bladder bag 3 (components such as the slurry tank, grouting pump, pressure gauge, and grouting valve connected to the inlet of the grouting pipe 4 are not shown in the figure). The grouting pipe 4 is provided with a front one - way valve 5 located in the front bladder bag 2, a rear one - way valve 6 located in the rear bladder bag 3, and a blasting valve 7 located between the front bladder bag 2 and the rear bladder bag 3. The extraction pipe 1 is also provided with a radial expander located between the front bladder bag 2 and the rear bladder bag 3, and a liquid injection pipeline 8 passing through the rear bladder bag 3 is connected to the rear end of the radial expander.

[0024] The radial expander includes a rubber tube 9 coaxially arranged outside the gas drainage pipe 1. A rigid thin tube 10 is fixedly arranged inside the inner circle of the rubber tube 9. Central supports 11 sleeved on the gas drainage pipe 1 are respectively arranged on the inner circles of the front side and the rear side of the rigid thin tube 10. The pipe wall of the rubber tube 9 is a double-layer structure with a sealed cavity. A number of slurry permeation holes 12 penetrating through inside and outside in the radial direction are arranged on the rubber tube 9 and the rigid thin tube 10. A liquid injection port 13 connected to the front port of the liquid injection pipeline 8 is arranged at the rear end of the rubber tube 9.

[0025] The central support 11 includes a positioning ring 14 sleeved on the gas drainage pipe 1. A setscrew 15 pressing against the gas drainage pipe 1 is threadedly connected to the positioning ring 14. Three support rods 16 are evenly arranged on the outer circle of the positioning ring 14 along the circumferential direction. The length of each support rod 16 is along the radial direction of the positioning ring 14. The outer end of the support rod 16 is fixedly connected to the inner circle of the rigid thin tube 10.

[0026] The inlet end of the liquid injection pipeline 8 is connected to a liquid storage tank 17. A liquid injection pump 18, a valve 19 and a pressure gauge 20 are sequentially arranged on the liquid injection pipeline 8 along the liquid flow direction.

[0027] S2. Open the valve 19 and start the liquid injection pump 18. Inject clear water into the rubber tube 9 through the liquid injection pipeline 8. The rubber tube 9 expands by water injection inside. The outer circle of the rubber tube 9 is tightly pressed against the inner wall of the drill hole 21. When the liquid injection pressure is not less than the predetermined grouting hole sealing pressure P, turn off the liquid injection pump 18 and the valve 19; S3. Inject slurry into the front bladder 2 and the rear bladder 3 through the grouting pipe 4. When the front bladder 2 and the rear bladder 3 are filled with slurry, continue to increase the grouting pressure. After reaching the bursting pressure P1 (such as 1.5 Mpa - 2 Mpa) of the bursting valve 7, the bursting valve 7 opens. The slurry is injected into the drill hole 21 between the front bladder 2 and the rear bladder 3. The slurry is injected into the cracks of the drill hole 21 wall through the slurry permeation holes 12 on the rubber tube 9. When the grouting pressure reaches the grouting hole sealing pressure P, the first hole sealing is completed; S4. Drain the gas in the drill hole 21 through the gas drainage pipe 1; S5. During the gas drainage process, when it is detected that the gas drainage concentration decreases, open the valve 19 on the liquid injection pipeline 8 and start the liquid injection pump 18. Inject clear water into the rubber tube 9 again. The rubber tube 9 continues to expand. The outer circle of the rubber tube 9 further presses against and seals the inner wall of the drill hole 21. When the liquid injection pressure reaches the set supplementary pressure hole sealing pressure P2 and is maintained for a period of time, and it is detected that the gas concentration rises and returns to the original state, turn off the liquid injection pump 18 and the valve 19; S6. Continue the gas drainage. If it is detected that the gas drainage concentration decreases, repeat step S5.

[0028] The slurry described in step S3 is uniformly mixed by an environment-friendly hole sealing material and water in a mass ratio of 1:1; The environment-friendly hole-sealing material is made by mixing raw materials with the following weight ratios: 700 - 800 parts of Portland cement, 30 - 50 parts of superabsorbent resin, 30 - 50 parts of coal gangue powder, 30 - 50 parts of quick-setting agent, and 30 - 50 parts of expansive agent; the particle sizes of all raw materials are 80 - 200 mesh.

[0029] By weight percentage, the superabsorbent resin is composed of 75% sodium polyacrylate, 24% polyacrylic acid, 0.7% SiO2, and 0.3% Al2(SO4)3; The Portland cement is 42.5 grade ordinary Portland cement; The coal gangue powder is made from the coal gangue produced during the coal mining process through crushing.

[0030] The above embodiments illustrate the basic principles and characteristics of the present invention. However, the above only illustrates the preferred embodiments of the present invention and is not limited by the described embodiments. Under the inspiration of this patent, those of ordinary skill in the art can also make many forms of deformation and improvement without departing from the purpose of the present invention and the scope protected by the claims. These all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be subject to the appended claims.

Claims

1. A method for regulating the sealing performance of boreholes during gas drainage, characterized in that: It includes the following steps: S1. Install the hole - sealing and pressure - compensating device on the gas - drainage pipe and push it forward from the back into the borehole; S2. Inject water into the hole - sealing and pressure - compensating device. When the injection pressure is not less than the predetermined grouting hole - sealing pressure P, stop injecting water; S3. Then inject grout into the hole - sealing and pressure - compensating device. When the grouting pressure reaches the grouting hole - sealing pressure P, complete the first hole - sealing; S4. Drain the gas in the borehole through the gas - drainage pipe; S5. During the gas drainage process, when it is detected that the gas - drainage concentration decreases, inject water for pressure compensation into the hole - sealing and pressure - compensating device in the same way as in step S2. When it is detected that the gas concentration increases and returns to the original state, stop injecting water for pressure compensation; S6. Continue gas drainage. If it is detected that the gas - drainage concentration decreases, repeat step S5.

2. The method for regulating the sealing performance of boreholes during gas drainage according to claim 1, wherein: The hole - sealing and pressure - compensating device includes a front bladder and a rear bladder arranged at intervals on the gas - drainage pipe from front to back. There is a grouting pipe parallel to the gas - drainage pipe between the front bladder and the rear bladder. The grouting pipe is provided with a front one - way valve located in the front bladder, a rear one - way valve located in the rear bladder, and a blasting valve located between the front bladder and the rear bladder. The gas - drainage pipe is also provided with a radial expander located between the front bladder and the rear bladder. The rear end of the radial expander is connected with a liquid - injection pipeline passing through the rear bladder.

3. The method for regulating the sealing performance of boreholes during gas drainage according to claim 2, characterized in that: The radial expander includes a rubber tube coaxially arranged outside the gas - drainage pipe. A rigid thin tube is fixedly arranged on the inner circle of the rubber tube. Central brackets sleeved on the gas - drainage pipe are respectively arranged on the front inner circle and the rear inner circle of the rigid thin tube. The pipe wall of the rubber tube is a double - layer structure with a sealed cavity. A number of slurry - permeating holes penetrating inside and outside in the radial direction are arranged on the rubber tube and the rigid thin tube. The rear end of the rubber tube is provided with a liquid - injection port connected to the front port of the liquid - injection pipeline.

4. The method for regulating the sealing performance of boreholes during gas drainage according to claim 3, wherein: The central bracket includes a positioning ring sleeved on the gas - drainage pipe. A jackscrew pressing against the gas - drainage pipe is threadedly connected to the positioning ring. Three support rods are evenly arranged on the outer circle of the positioning ring along the circumferential direction. The length of each support rod is along the radial direction of the positioning ring, and the outer end of the support rod is fixedly connected to the inner circle of the rigid thin tube.

5. The method for regulating the sealing performance of boreholes during gas drainage according to claim 4, characterized in that: The inlet end of the liquid - injection pipeline is connected with a liquid storage tank. A liquid - injection pump, a valve, and a pressure gauge are successively arranged on the liquid - injection pipeline along the liquid - flow direction.

6. The method for regulating the sealing performance of boreholes during gas drainage according to claim 5, wherein: The specific process of step S2 is as follows: Open the valve, start the liquid - injection pump, inject clear water into the rubber tube through the liquid - injection pipeline. The rubber tube expands due to water injection inside, and the outer circle of the rubber tube is tightly pressed against the inner wall of the borehole. When the injection pressure is not less than the predetermined grouting hole - sealing pressure P, close the liquid - injection pump and the valve.

7. The method for regulating the sealing performance of boreholes during gas drainage according to claim 6, characterized in that: The specific process of step S3 is as follows: Inject slurry into the front bladder and the rear bladder through the grouting pipe. After the front bladder and the rear bladder are filled with slurry, continue to increase the grouting pressure. After reaching the blasting pressure P1 of the blasting valve, the blasting valve opens, and the slurry is injected into the borehole between the front bladder and the rear bladder. The slurry is injected into the cracks in the borehole wall through the slurry - permeating holes on the rubber tube. When the grouting pressure reaches the grouting hole - sealing pressure P, complete the first hole - sealing.

8. The method for regulating the sealing performance of boreholes during gas drainage according to claim 7, wherein: The specific process of step S5 is as follows: during the gas drainage process, when the detected gas drainage concentration decreases, open the valve on the liquid injection pipeline, start the liquid injection pump, and inject clear water into the rubber tube again. The rubber tube continues to expand, and the outer circle of the rubber tube further presses against and seals the inner wall of the drilling hole. When the injection pressure reaches the set supplementary pressure sealing hole pressure P2 and is maintained for a period of time, and it is detected that the gas concentration rises and returns to the original state, turn off the liquid injection pump and the valve.

9. The method for regulating the sealing performance of boreholes during gas drainage according to claim 7, wherein: The slurry is made by uniformly mixing an environment-friendly hole-sealing material and water in a mass ratio of 1:1; The environment-friendly hole-sealing material is made by mixing raw materials with the following weight ratios: 700 - 800 parts of portland cement, 30 - 50 parts of superabsorbent resin, 30 - 50 parts of coal gangue powder, 30 - 50 parts of quick-setting agent, and 30 - 50 parts of expansive agent; the particle sizes of all raw materials are 80 - 200 mesh.

10. The method for regulating the sealing performance of boreholes during gas drainage according to claim 9, wherein: By weight percentage, the superabsorbent resin is made by mixing 75% of sodium polyacrylate, 24% of polyacrylic acid, 0.7% of SiO2, and 0.3% of Al2(SO4)3; The portland cement is 42.5 grade ordinary portland cement; The coal gangue powder is made from the coal gangue generated during the coal mine production process through crushing.

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