Gas extraction method and system based on non-solidifying sealing material

Abstract

A system for gas extraction based on a non-solidifying sealing material, including a support assembly, a gas extraction pipe, a gas extraction device, two sealing water bags, a water injection and drainage device, a grouting device, a slurry discharge device, and a central control unit. The two sealing water bags are injected with water and expanded to offer a sealing effect. The grouting device is connected to a grouting pipe configured for injecting the non-solidifying sealing material into a sealing segment of a borehole. The slurry discharge device is configured to discharge slurry. The water injection and drainage device is configured to drain water from the two sealing water bags. The support assembly is recovered through a hook rod and an engagement hole. A gas extraction method using such system is also provided.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority from Chinese Patent Application No. 202510759081.1, filed on Jun. 9, 2025. The content of the aforementioned application, including any intervening amendments thereto, is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This application relates to mine gas control, and more particularly to a gas extraction method and a system based on a non-solidifying sealing material.BACKGROUND

[0003] Gas extraction is a core strategy for preventing gas accidents in China's coal mines and plays a vital role in the gas disaster prevention and control system. However, field data show that approximately 65% of boreholes in longwall mining faces have gas pre-extraction concentrations below 30%. As a result, the gas pre-extraction rate often fails to meet required standards. Borehole sealing is a critical step in this process. Traditional solidifying sealing materials tend to crack after borehole sealing due to coal seam deformation and other factors, causing gas leakage. In contrast, non-solidifying sealing materials offer an emerging and effective solution. These non-solidifying sealing materials remain in a non-solidified or semi-fluid state, allowing them to adapt flexibly to complex borehole conditions. They can self-adjust with minor coal seam movements, performing a reliable seal on surrounding gaps. Moreover, the non-solidifying sealing materials can be pressure-injected into boreholes using grouting pumps, thoroughly filling all potential fractures in the coal and rock. Even if borehole deformation occurs later, re-grouting can restore sealing integrity. This approach effectively resolves key limitations of solid sealing materials, such as crack formation, seal failure, and rapid decline in gas extraction concentration, providing more stable and durable sealing performance.

[0004] Chinese patent publication No. 212130542U disclosed a non-solidifying constant-pressure slurry sealing bag system for gas extraction boreholes. However, its grouting auxiliary pipes require drilling on both upper and lower sides of the borehole, increasing the risk of borehole collapse. Additionally, the non-solidifying material is injected into the bags, offering no structural support to the borehole. Pressure sensors are also arranged in both bags and the grouting pipe, with no recovery process provided, leading to higher costs.

[0005] Chinese patent publication No. 105114030A disclosed a non-solidifying constant-pressure slurry sealing method for gas extraction boreholes. Yet it relies on polyurethane sealing material, which is expensive, may release harmful gases, and prevents recovery of components such as gas extraction pipes.

[0006] Chinese patent publication No. 111561291B disclosed a double-layer extrusion-type sealing device and a method thereof. Both front and rear sealing capsules adopts water-activated expansive agents for sealing. However, the gas extraction pipe cannot be recovered, featuring poor cost effectiveness.

[0007] In summary, there is an urgent need to develop a new sealing device and method for gas extraction boreholes in coal mines based on non-solidifying materials, having advantages of high reliability, low cost and practical application. It will significantly contribute to the sustainable and safe development of coal mining operations.SUMMARY

[0008] The present disclosure provides a gas extraction method and a system based on a non-solidifying sealing material, so as to address the technical problems in the prior art, such as low reliability, low efficiency and high cost.

[0009] In order to address the aforementioned technical problems, the present disclosure adopts the following technical solutions.

[0010] A system for gas extraction based on a non-solidifying sealing material, comprising:

[0011] a support assembly;

[0012] a gas extraction pipe;

[0013] a gas extraction device;

[0014] a first sealing water bag;

[0015] a second sealing water bag;

[0016] a water injection and drainage device;

[0017] a grouting device;

[0018] a slurry discharge device; and

[0019] a central control unit;

[0020] wherein the support assembly is arranged at a middle of a sealing segment of a borehole; the support assembly comprises an outer support sleeve; a central tube is arranged along a central axis of the outer support sleeve; a plurality of support vertical plates are fixedly connected to an interior of the outer support sleeve; and those among the plurality of support vertical plates arranged between the outer support sleeve and an outer wall of the central tube are each provided with an engagement hole;

[0021] the gas extraction pipe is configured to pass through the central tube, and is located at a center of the borehole;

[0022] the gas extraction device is connected to an end of the gas extraction pipe;

[0023] the first sealing water bag is arranged at a front end of the support assembly, and the second sealing water bag is arranged at a rear end of the support assembly;

[0024] the water injection and drainage device is connected to a water injection pipe; an end of the water injection pipe is connected to the first sealing water bag and the second sealing water bag; and the water injection pipe is provided with a first valve;

[0025] the grouting device is connected to a grouting pipe extending into the sealing segment; and the grouting pipe is provided with a pressure valve;

[0026] the slurry discharge device is connected to a slurry discharge pipe extending into the sealing segment; and the slurry discharge pipe is provided with a second valve; and

[0027] the central control unit is electrically connected to the water injection and drainage device, the gas extraction device, the grouting device, the slurry discharge device, the first valve, the pressure valve and the second valve, and is configured to control the water injection and drainage device, the gas extraction device, the grouting device, the slurry discharge device, the first valve, the pressure valve and the second valve.

[0028] In some embodiments, an extraction end of the gas extraction pipe is sleeved with a fixing device;

[0029] the fixing device comprises a square housing, a cylindrical inner tube, a plurality of fixing claws, a drive mechanism, four horizontal screws and four vertical screws;

[0030] the cylindrical inner tube is fixed inside the square housing;

[0031] a plurality of connecting pillars are fixedly connected between an outer wall of the cylindrical inner tube and an inner wall of the square housing;

[0032] the plurality of fixing claws are uniformly arranged at an inner periphery of the cylindrical inner tube;

[0033] the drive mechanism comprises four drive motors; the four drive motors are arranged inside the square housing, and are electrically connected to the central control unit; an output shaft of each of the four drive motors is provided with a vertical gear; the vertical gear is engaged with a horizontal gear; output shafts of two of the four drive motors face toward a first side wall of the square housing; and output shafts of the other two of four drive motors face toward a second side wall of the square housing;

[0034] two of the four horizontal screws are arranged on the first side wall of the square housing, and the other two of the four horizontal screws are arranged on the second side wall of the square housing; a first end of each of the four horizontal screws is configured to extend out of the square housing, and is fixedly connected to a first bracing claw; and a second end of each of the four horizontal screws is arranged inside the square housing, and is engaged with the horizontal gear; and

[0035] two of the four vertical screws are arranged on an upper wall of the square housing, and the other two of the four vertical screws are arranged on a lower wall of the square housing; a first end of each of the four vertical screws is configured to extend out of the square housing, and is fixedly connected to a second bracing claw; and a second end of each of the four vertical screws is engaged with the vertical gear.

[0036] In some embodiments, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction method is performed using the aforementioned system, and the gas extraction method comprises:

[0037] (S1) passing the gas extraction pipe through the central tube of the support assembly followed by insertion into the borehole; passing the first sealing water bag and the second sealing water bag connected to the water extraction pipe through gaps within the support assembly, and arranging the first sealing water bag and the second sealing water bag at the front end and the rear end of the support assembly, respectively; and arranging an end of the grouting pipe within a gap between the second sealing water bag and the support assembly;

[0038] (S2) activating the water injection and drainage device to inject water into the first sealing water bag and the second sealing water bag until a first preset pressure is reached to expand the first sealing water bag and the second sealing water bag for sealing; and closing the first valve on the water injection pipe and deactivating the water injection and drainage device;

[0039] (S3) opening the pressure valve on the grouting pipe, and activating the grouting device to inject a non-solidifying sealing slurry into the sealing segment of the borehole; and closing the pressure valve and deactivating the grouting device until a second preset pressure is reached;

[0040] (S4) activating the gas extraction device to perform gas extraction, wherein the gas extraction device is provided with a gas concentration monitoring module; and when a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve on the grouting pipe, opening the pressure valve and activating the grouting device to perform grouting again until the second preset pressure is reached and a current extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing;

[0041] (S5) after completion of gas extraction, opening the second valve on the slurry discharge pipe, and activating the slurry discharge device to discharge the non-solidifying sealing slurry from the sealing segment; opening the first valve on the water injection pipe and activating the water injection and drainage device to drain water from the first sealing water bag and the second sealing water bag; and

[0042] (S6) retrieving the first sealing water bag and the second sealing water bag the water injection pipe, the grouting pipe and the slurry discharge pipe; engaging a hook rod with the engagement hole of the support assembly to sequentially take out the support assembly and the gas extraction pipe; and cleaning all components of the system to enable recovery.

[0043] In some embodiments, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction method is performed using the aforementioned system, and the gas extraction method comprises:

[0044] (S1) passing the gas extraction pipe through the central tube of the support assembly followed by insertion into the borehole; mounting the fixing device onto the extraction end of the gas extraction pipe; activating the four drive motors to drive the four horizontal screws and the four vertical screws to extend out of the square housing, such that first bracing claws and second bracing claws abut against an inner wall of the borehole to secure the gas extraction pipe; passing the first sealing water bag and the second sealing water bag connected to the water injection pipe through gaps within the support assembly and arranging the first sealing water bag and the second sealing water bag at the front end and the rear end of the support assembly, respectively; and arranging an end of the grouting pipe within a gap between the second sealing water bag and the support assembly;

[0045] (S2) activating the water injection and drainage device to inject water into the first sealing water bag and the second sealing water bag until a first preset pressure is reached to expand the first sealing water bag and the second sealing water bag for sealing; and closing the first valve on the water injection pipe and deactivating the water injection and drainage device;

[0046] (S3) opening the pressure valve on the grouting pipe and activating the grouting device to inject a non-solidifying sealing slurry into the sealing segment of the borehole; and closing the pressure valve and deactivating the grouting device until a second preset pressure is reached;

[0047] (S4) activating the gas extraction device to perform gas extraction, wherein the gas extraction device is provided with a gas concentration monitoring module; and when a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve on the grouting pipe, opening the pressure valve and activating the grouting device to perform grouting again until the second preset pressure is reached and an extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing;

[0048] (S5) after completion of gas extraction, opening the second valve on the slurry discharge pipe and activating the slurry discharge device to discharge the non-solidifying sealing slurry from the sealing segment, and opening the first valve on the water injection pipe and activating the water injection and drainage device to drain water from the first sealing water bag and the second sealing water bag; and

[0049] (S6) retrieving the first sealing water bag, the second sealing water bag, the water injection pipe, the grouting pipe and the slurry discharge pipe; engaging a hook rod with the engagement hole of the support assembly to take out the support assembly; activating the four drive motors to retract the four horizontal screws and the four vertical screws; and taking out the gas extraction pipe and the fixing device, followed by cleaning to enable recovery of the system.

[0050] Compared to the prior art, the present disclosure has the following beneficial effects.

[0051] This disclosure significantly improves sealing efficiency and borehole utilization in gas extraction process while ensuring reliable sealing performance.

[0052] (1) A Custom supporting structure combined with sealing water bags is employed. The central control unit synchronizes the grouting and gas extraction devices to maintain dynamic sealing throughout the gas extraction process.

[0053] (2) The central control unit controls the water drainage system, the slurry discharge device, and the hook rod, enabling full recovery of the system after use.

[0054] (3) A dedicated extraction pipe fixation mechanism stabilizes the pipe during operation, effectively preventing vibration-induced efficiency loss and excessive wear.

[0055] The method is simple to implement, easy to operate, highly reliable, and cost-effective, making it well-suited for widespread adoption in gas extraction boreholes across coal mines.BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 schematically shows a system for gas extraction based on a non-solidifying sealing material according to an embodiment of the present disclosure;

[0057] FIG. 2 schematically shows a support assembly according to an embodiment of the present disclosure;

[0058] FIG. 3 schematically shows a hook rod according to an embodiment of the present disclosure; and

[0059] FIG. 4 schematically shows a fixing device of a gas extraction pipe according to an embodiment of the present disclosure.

[0060] In the figures: 1—gas extraction pipe; 2—water injection pipe; 3—second sealing water bag; 4—frist valve; 5—water injection and drainage device; 6—gas extraction device; 7—central control unit; 8—grouting device; 9—pressure valve; 10—slurry discharge device; 11—second valve; 12—slurry discharge pipe; 13—grouting pipe; 14—support assembly; 15—outer support sleeve; 16—central tube; 17—support vertical plate; 18—engagement hole; 19—hook rod; 20—frist sealing water bag; 21—fixing device; 22—connecting pillar; 23—cylindrical inner tube; 24—fixing claw; 25—drive motor; 26—vertical gear; 27—horizontal gear; 28—horizontal screw; 29—vertical screw; 30—second bracing claw; 31—square housing; and 32—first bracing claw.DETAILED DESCRIPTION OF EMBODIMENTS

[0061] The present disclosure will be further illustrated in combination with the embodiments.Embodiment 1

[0062] Referring to FIG. 1, a system for gas extraction based on a non-solidifying sealing material includes a support assembly 14, a gas extraction pipe 1, a gas extraction device 6, a first sealing water bag 20, a second sealing water bag 3, a water injection and drainage device 5, a grouting device 8, a slurry discharge device 10 and a central control unit 7.

[0063] The support assembly 14 is arranged at a middle of a sealing segment of a borehole, and is configured to support the borehole. Referring to FIG. 2, the support assembly 14 includes an outer support sleeve 15. A central tube 16 is arranged along a central axis of the outer support sleeve 15. A plurality of support vertical plates 17 are fixedly connected to an interior of the outer support sleeve 15, and those among the plurality of support vertical plates 17 arranged between the outer support sleeve 15 and an outer wall of the central tube 16 are each provided with an engagement hole 18. The support assembly 14 is provided with a hook rod 19.

[0064] Referring to FIG. 3, during the retraction of the support assembly 14, the hook rod 19 is operated through a robotic arm controlled via the central control unit 7. A size of the support assembly 14 is set according to a diameter of the borehole. The support assembly 14 can be arranged in the sealing segment or other segments of the borehole for supporting.

[0065] The gas extraction pipe 1 is configured to pass through the central tube 16, and is located at a center of the borehole. The gas extraction pipe 1 is configured for gas extraction. The gas extraction device 6 is connected to an end of the gas extraction pipe 1, and is provided with a gas concentration monitoring module. The gas concentration monitoring module is configured to monitor gas extraction concentration during the gas extraction.

[0066] The first sealing water bag 20 is arranged at a front end of the support assembly 14, and the second sealing water bag 3 is arranged at a rear end of the support assembly 14.

[0067] The water injection and drainage device 5 is connected to a water injection pipe 2. An end of the water injection pipe 2 is connected to the first sealing water bag 20 and the second sealing water bag 3. The water injection pipe 2 is provided with a first valve 4. The first valve 4 is configured for water injection and drainage of the first sealing water bag 20 and the second sealing water bag 3.

[0068] The grouting device 8 is connected to a grouting pipe 13 extending into the sealing segment. The grouting pipe 13 is provided with a pressure valve 9. A non-solidifying sealing material with a preset pressure is injected into the sealing segment through the grouting pipe 13. The pressure valve 9 is configured to monitor a pressure of the sealing segment. When the pressure and the gas extraction concentration decrease, the pressure valve 9 automatically opens, such that the grouting device 8 inject a slurry into the sealing segment until the preset pressure is reached. At that point, the sealing is completed and the pressure valve 9 closes.

[0069] The slurry discharge device 10 is connected to a slurry discharge pipe 12 extending into the sealing segment. The slurry discharge pipe 12 is provided with a second valve 11 to discharge and recycle the non-solidifying sealing material after use.

[0070] The central control unit 7 is electrically connected to the water injection and drainage device 5, the gas extraction device 6, the grouting device 8, the slurry discharge device 10, the first valve 4, the pressure valve 9 and the second valve 11, and is configured to control the water injection and drainage device 5, the gas extraction device 6, the grouting device 8, the slurry discharge device 10, the first valve 4, the pressure valve 9 and the second valve 11. The aforementioned components are integrally controlled by the central control unit 7, and are operated in conjunction.Embodiment 2

[0071] In this embodiment, an extraction end of the gas extraction pipe 1 is sleeved with a fixing device 21.

[0072] Referring to FIG. 4, the fixing device 21 includes a square housing 31, a cylindrical inner tube 23, a plurality of fixing claws 24, a drive mechanism, four horizontal screws 28 and four vertical screws 29. The cylindrical inner tube 23 is fixed inside the square housing 31. A plurality of connecting pillars 22 are fixedly connected between an outer wall of the cylindrical inner tube 23 and an inner wall of the square housing 31. The plurality of fixing claws 24 are uniformly arranged at an inner periphery of the cylindrical inner tube 23.

[0073] The drive mechanism includes four drive motors 25. The four drive motors 25 are arranged inside the square housing 31, and are electrically connected to the central control unit 7. An output shaft of each of the four drive motors 25 is provided with a vertical gear 26. The vertical gear 26 is engaged with a horizontal gear 27. Output shafts of two of the four drive motors 25 face toward a first side wall of the square housing 31. Output shafts of the other two of four drive motors 25 face toward a second side wall of the square housing 31.

[0074] Two of the four horizontal screws 28 are arranged on the first side wall of the square housing 31. The other two of the four horizontal screws 28 are arranged on the second side wall of the square housing 31. A first end of each of the four horizontal screws 28 is configured to extend out of the square housing 31, and is fixedly connected to a first bracing claw 32. A second end of each of the four horizontal screws 28 is arranged inside the square housing, and is engaged with the horizontal gear 27.

[0075] Two of the four vertical screws 29 are arranged on an upper side wall of the square housing 31. The other two of the four vertical screws 29 are arranged on a lower side wall of the square housing 31. A first end of each of the four vertical screws 29 is configured to extend out of the square housing 31, and is fixedly connected to a second bracing claw 30. A second end of each of the four vertical screws 29 is engaged with the vertical gear 26.

[0076] The fixing device 21 is configured to fix the gas extraction pipe 1 and prevent its vibration. The fixing device 21 is connected to the end of the gas extraction pipe 1. The central control unit 7 is connected to a control wire to control the drive motor 25 to rotate, thereby controlling the vertical gear 26 to rotate. The vertical gear 26 is engaged with the horizontal gear 27 and each of the four vertical screws 29, driving them to rotate. The horizontal gear 27 is engaged with each of the four horizontal screws 28, driving it to rotate. The rotations of the four horizontal screws 28 and the four vertical screws 29 enable extension and retraction functions. The second bracing claw 30 contacts a wall of the borehole to secure the square housing 31. The square housing 31 is connected to the cylindrical inner tube 23 via the plurality of connecting pillars 22. The cylindrical inner tube 23 has the fixing claw 24, which attaches to the end of the gas extraction pipe 1, thus securing the gas extraction pipe 1.Embodiment 3

[0077] In this embodiment, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction method is performed using the system in the embodiment 1, and is performed through the following steps.

[0078] (S1) The gas extraction pipe 1 passes through the central tube 16 of the support assembly 14 followed by insertion into the borehole. The first sealing water bag 20 and the second sealing water bag 3 connected to the water injection pipe 2 pass through gaps within the support assembly 14, where the water injection pipe 2 is configured to pass through a gap between the outer support sleeve 15 of the support assembly 14 and the plurality of support vertical plates 17, and the gas extraction pipe 1 is configured to pass through a gap within the central tube 16 of the support assembly 14. The first sealing water bag 20 and the second sealing water bag 3 are arranged at the front end and the rear end of the support assembly 14, respectively. An end of the grouting pipe 13 is arranged within a gap between the second sealing water bag 3 and the support assembly 14.

[0079] (S2) The water injection and drainage device 5 is activated to inject water into the first sealing water bag 20 and the second sealing water bag 3 until a first preset pressure is reached to expand the first sealing water bag 20 and the second sealing water bag 3 for sealing. The first valve 4 on the water injection pipe 2 is closed, and the water injection and drainage device 5 is deactivated.

[0080] (S3) The pressure valve 9 on the grouting pipe 13 is opened, and the grouting device 8 is activated to inject the non-solidifying sealing slurry into the sealing segment of the borehole. The pressure valve 9 is closed and the grouting device 8 is deactivated until a second preset pressure is reached.

[0081] (S4) The gas extraction device 6 is activated to perform gas extraction, where the gas extraction device 6 is provided with a gas concentration monitoring module. When a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve 9 on the grouting pipe 13, the pressure valve 9 is opened and the grouting device 8 is activated to perform grouting again until the second preset pressure is reached and a current extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing.

[0082] (S5) After completion of gas extraction, the second valve 11 on the slurry discharge pipe 12 is opened, and the slurry discharge device 10 is activated to discharge the non-solidifying sealing slurry from the sealing segment. The first valve 4 on the water injection pipe 2 is opened and the water injection and drainage device 5 is activated to drain water from the first sealing water bag 20 and the second sealing water bag 3.

[0083] (S6) The first sealing water bag 20, the second sealing water bag 3, the water injection pipe 2, the grouting pipe 13 and the slurry discharge pipe 12 are retrieved. The hook rod 19 is engaged with the engagement hole 18 of the support assembly 14 to sequentially take out the support assembly 14 and the gas extraction pipe 1. All components of the system are cleaned to enable recovery.Embodiment 4

[0084] In this embodiment, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction is performed using the system in the embodiment 2, and is performed through the following steps.

[0085] (a) The gas extraction pipe 1 passes through the central tube 16 of the support assembly 14 followed by insertion into the borehole. The fixing device 21 is mounted onto the extraction end of the gas extraction pipe 1. The four drive motors 25 are activated to drive the four horizontal screws 28 and the four vertical screws 29 to extend out of the square housing 31, such that first bracing claws 32 and second bracing claws 30 abut against an inner wall of the borehole to secure the gas extraction pipe 1. The first sealing water bag 20 and the second sealing water bag 3 connected to the water injection pipe 2 pass through gaps within the support assembly 14, where the water injection pipe 2 is configured to pass through a gap between the outer support sleeve 15 of the support assembly 14 and the plurality of support vertical plates 17, and the gas extraction pipe 1 is configured to pass through a gap within the central tube 16 of the support assembly 14. The first sealing water bag 20 and the second sealing water bag 3 are arranged at the front end and the rear end of the support assembly 14, respectively. An end of the grouting pipe 13 is arranged within a gap between the second sealing water bag 3 and the support assembly 14.

[0086] (b) The water injection and drainage device 5 is activated to inject water into the first sealing water bag 20 and the second sealing water bag 3 until a first preset pressure is reached to expand the first sealing water bag 20 and the second sealing water bag 3 for sealing. The first valve 4 on the water injection pipe 2 is closed, and the water injection and drainage device 5 is deactivated.

[0087] (c) The pressure valve 9 on the grouting pipe 13 is opened, and the grouting device 8 is activated to inject the non-solidifying sealing slurry into the sealing segment of the borehole. The pressure valve 9 is closed and the grouting device 8 is deactivated until a second preset pressure is reached.

[0088] (d) The gas extraction device 6 is activated to perform gas extraction, where the gas extraction device 6 is provided with a gas concentration monitoring module. When a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve 9 on the grouting pipe 13, the pressure valve 9 is opened and the grouting device 8 is deactivated to perform grouting again until the second preset pressure is reached and an extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing.

[0089] (e) After completion of gas extraction, the second valve 11 on the slurry discharge pipe 12 is opened, and the slurry discharge device 10 is activated to discharge the non-solidifying sealing slurry from the sealing segment. The first valve 4 on the water injection pipe 2 is opened and the water injection and drainage device 5 is activated to drain water from the first sealing water bag 20 and the second sealing water bag 3.

[0090] (f) The first sealing water bag 20, the second sealing water bag 3, the water injection pipe 2, the grouting pipe 13 and the slurry discharge pipe 12 are retrieved. The hook rod 19 is engaged with the engagement hole 18 of the support assembly 14 to take out the support assembly 14. The four drive motors 25 are activated to retract the four horizontal screws 28 and the four vertical screws 29. The gas extraction pipe 1 and the fixing device 21 are taken out, followed by cleaning to enable recovery of the system.

[0091] It should be noted that the embodiments described above are merely illustrative, and are not intended to limit the present disclosure. For those skilled in the art, any modifications can be made to this disclosure in forms and details without paying creative labor, and shall fall within the scope of the disclosure defined by the appended claims.

Examples

embodiment 1

[0062]Referring to FIG. 1, a system for gas extraction based on a non-solidifying sealing material includes a support assembly 14, a gas extraction pipe 1, a gas extraction device 6, a first sealing water bag 20, a second sealing water bag 3, a water injection and drainage device 5, a grouting device 8, a slurry discharge device 10 and a central control unit 7.

[0063]The support assembly 14 is arranged at a middle of a sealing segment of a borehole, and is configured to support the borehole. Referring to FIG. 2, the support assembly 14 includes an outer support sleeve 15. A central tube 16 is arranged along a central axis of the outer support sleeve 15. A plurality of support vertical plates 17 are fixedly connected to an interior of the outer support sleeve 15, and those among the plurality of support vertical plates 17 arranged between the outer support sleeve 15 and an outer wall of the central tube 16 are each provided with an engagement hole 18. The support assembly 14 is provid...

embodiment 2

[0071]In this embodiment, an extraction end of the gas extraction pipe 1 is sleeved with a fixing device 21.

[0072]Referring to FIG. 4, the fixing device 21 includes a square housing 31, a cylindrical inner tube 23, a plurality of fixing claws 24, a drive mechanism, four horizontal screws 28 and four vertical screws 29. The cylindrical inner tube 23 is fixed inside the square housing 31. A plurality of connecting pillars 22 are fixedly connected between an outer wall of the cylindrical inner tube 23 and an inner wall of the square housing 31. The plurality of fixing claws 24 are uniformly arranged at an inner periphery of the cylindrical inner tube 23.

[0073]The drive mechanism includes four drive motors 25. The four drive motors 25 are arranged inside the square housing 31, and are electrically connected to the central control unit 7. An output shaft of each of the four drive motors 25 is provided with a vertical gear 26. The vertical gear 26 is engaged with a horizontal gear 27. Out...

embodiment 3

[0077]In this embodiment, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction method is performed using the system in the embodiment 1, and is performed through the following steps.[0078](S1) The gas extraction pipe 1 passes through the central tube 16 of the support assembly 14 followed by insertion into the borehole. The first sealing water bag 20 and the second sealing water bag 3 connected to the water injection pipe 2 pass through gaps within the support assembly 14, where the water injection pipe 2 is configured to pass through a gap between the outer support sleeve 15 of the support assembly 14 and the plurality of support vertical plates 17, and the gas extraction pipe 1 is configured to pass through a gap within the central tube 16 of the support assembly 14. The first sealing water bag 20 and the second sealing water bag 3 are arranged at the front end and the rear end of the support assembly 14, res...

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority from Chinese Patent Application No. 202510759081.1, filed on Jun. 9, 2025. The content of the aforementioned application, including any intervening amendments thereto, is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] This application relates to mine gas control, and more particularly to a gas extraction method and a system based on a non-solidifying sealing material.BACKGROUND

[0003] Gas extraction is a core strategy for preventing gas accidents in China's coal mines and plays a vital role in the gas disaster prevention and control system. However, field data show that approximately 65% of boreholes in longwall mining faces have gas pre-extraction concentrations below 30%. As a result, the gas pre-extraction rate often fails to meet required standards. Borehole sealing is a critical step in this process. Traditional solidifying sealing materials tend to crack after borehole sealing due to coal seam deformation and other factors, causing gas leakage. In contrast, non-solidifying sealing materials offer an emerging and effective solution. These non-solidifying sealing materials remain in a non-solidified or semi-fluid state, allowing them to adapt flexibly to complex borehole conditions. They can self-adjust with minor coal seam movements, performing a reliable seal on surrounding gaps. Moreover, the non-solidifying sealing materials can be pressure-injected into boreholes using grouting pumps, thoroughly filling all potential fractures in the coal and rock. Even if borehole deformation occurs later, re-grouting can restore sealing integrity. This approach effectively resolves key limitations of solid sealing materials, such as crack formation, seal failure, and rapid decline in gas extraction concentration, providing more stable and durable sealing performance.

[0004] Chinese patent publication No. 212130542U disclosed a non-solidifying constant-pressure slurry sealing bag system for gas extraction boreholes. However, its grouting auxiliary pipes require drilling on both upper and lower sides of the borehole, increasing the risk of borehole collapse. Additionally, the non-solidifying material is injected into the bags, offering no structural support to the borehole. Pressure sensors are also arranged in both bags and the grouting pipe, with no recovery process provided, leading to higher costs.

[0005] Chinese patent publication No. 105114030A disclosed a non-solidifying constant-pressure slurry sealing method for gas extraction boreholes. Yet it relies on polyurethane sealing material, which is expensive, may release harmful gases, and prevents recovery of components such as gas extraction pipes.

[0006] Chinese patent publication No. 111561291B disclosed a double-layer extrusion-type sealing device and a method thereof. Both front and rear sealing capsules adopts water-activated expansive agents for sealing. However, the gas extraction pipe cannot be recovered, featuring poor cost effectiveness.

[0007] In summary, there is an urgent need to develop a new sealing device and method for gas extraction boreholes in coal mines based on non-solidifying materials, having advantages of high reliability, low cost and practical application. It will significantly contribute to the sustainable and safe development of coal mining operations.SUMMARY

[0008] The present disclosure provides a gas extraction method and a system based on a non-solidifying sealing material, so as to address the technical problems in the prior art, such as low reliability, low efficiency and high cost.

[0009] In order to address the aforementioned technical problems, the present disclosure adopts the following technical solutions.

[0010] A system for gas extraction based on a non-solidifying sealing material, comprising:

[0011] a support assembly;

[0012] a gas extraction pipe;

[0013] a gas extraction device;

[0014] a first sealing water bag;

[0015] a second sealing water bag;

[0016] a water injection and drainage device;

[0017] a grouting device;

[0018] a slurry discharge device; and

[0019] a central control unit;

[0020] wherein the support assembly is arranged at a middle of a sealing segment of a borehole; the support assembly comprises an outer support sleeve; a central tube is arranged along a central axis of the outer support sleeve; a plurality of support vertical plates are fixedly connected to an interior of the outer support sleeve; and those among the plurality of support vertical plates arranged between the outer support sleeve and an outer wall of the central tube are each provided with an engagement hole;

[0021] the gas extraction pipe is configured to pass through the central tube, and is located at a center of the borehole;

[0022] the gas extraction device is connected to an end of the gas extraction pipe;

[0023] the first sealing water bag is arranged at a front end of the support assembly, and the second sealing water bag is arranged at a rear end of the support assembly;

[0024] the water injection and drainage device is connected to a water injection pipe; an end of the water injection pipe is connected to the first sealing water bag and the second sealing water bag; and the water injection pipe is provided with a first valve;

[0025] the grouting device is connected to a grouting pipe extending into the sealing segment; and the grouting pipe is provided with a pressure valve;

[0026] the slurry discharge device is connected to a slurry discharge pipe extending into the sealing segment; and the slurry discharge pipe is provided with a second valve; and

[0027] the central control unit is electrically connected to the water injection and drainage device, the gas extraction device, the grouting device, the slurry discharge device, the first valve, the pressure valve and the second valve, and is configured to control the water injection and drainage device, the gas extraction device, the grouting device, the slurry discharge device, the first valve, the pressure valve and the second valve.

[0028] In some embodiments, an extraction end of the gas extraction pipe is sleeved with a fixing device;

[0029] the fixing device comprises a square housing, a cylindrical inner tube, a plurality of fixing claws, a drive mechanism, four horizontal screws and four vertical screws;

[0030] the cylindrical inner tube is fixed inside the square housing;

[0031] a plurality of connecting pillars are fixedly connected between an outer wall of the cylindrical inner tube and an inner wall of the square housing;

[0032] the plurality of fixing claws are uniformly arranged at an inner periphery of the cylindrical inner tube;

[0033] the drive mechanism comprises four drive motors; the four drive motors are arranged inside the square housing, and are electrically connected to the central control unit; an output shaft of each of the four drive motors is provided with a vertical gear; the vertical gear is engaged with a horizontal gear; output shafts of two of the four drive motors face toward a first side wall of the square housing; and output shafts of the other two of four drive motors face toward a second side wall of the square housing;

[0034] two of the four horizontal screws are arranged on the first side wall of the square housing, and the other two of the four horizontal screws are arranged on the second side wall of the square housing; a first end of each of the four horizontal screws is configured to extend out of the square housing, and is fixedly connected to a first bracing claw; and a second end of each of the four horizontal screws is arranged inside the square housing, and is engaged with the horizontal gear; and

[0035] two of the four vertical screws are arranged on an upper wall of the square housing, and the other two of the four vertical screws are arranged on a lower wall of the square housing; a first end of each of the four vertical screws is configured to extend out of the square housing, and is fixedly connected to a second bracing claw; and a second end of each of the four vertical screws is engaged with the vertical gear.

[0036] In some embodiments, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction method is performed using the aforementioned system, and the gas extraction method comprises:

[0037] (S1) passing the gas extraction pipe through the central tube of the support assembly followed by insertion into the borehole; passing the first sealing water bag and the second sealing water bag connected to the water extraction pipe through gaps within the support assembly, and arranging the first sealing water bag and the second sealing water bag at the front end and the rear end of the support assembly, respectively; and arranging an end of the grouting pipe within a gap between the second sealing water bag and the support assembly;

[0038] (S2) activating the water injection and drainage device to inject water into the first sealing water bag and the second sealing water bag until a first preset pressure is reached to expand the first sealing water bag and the second sealing water bag for sealing; and closing the first valve on the water injection pipe and deactivating the water injection and drainage device;

[0039] (S3) opening the pressure valve on the grouting pipe, and activating the grouting device to inject a non-solidifying sealing slurry into the sealing segment of the borehole; and closing the pressure valve and deactivating the grouting device until a second preset pressure is reached;

[0040] (S4) activating the gas extraction device to perform gas extraction, wherein the gas extraction device is provided with a gas concentration monitoring module; and when a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve on the grouting pipe, opening the pressure valve and activating the grouting device to perform grouting again until the second preset pressure is reached and a current extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing;

[0041] (S5) after completion of gas extraction, opening the second valve on the slurry discharge pipe, and activating the slurry discharge device to discharge the non-solidifying sealing slurry from the sealing segment; opening the first valve on the water injection pipe and activating the water injection and drainage device to drain water from the first sealing water bag and the second sealing water bag; and

[0042] (S6) retrieving the first sealing water bag and the second sealing water bag the water injection pipe, the grouting pipe and the slurry discharge pipe; engaging a hook rod with the engagement hole of the support assembly to sequentially take out the support assembly and the gas extraction pipe; and cleaning all components of the system to enable recovery.

[0043] In some embodiments, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction method is performed using the aforementioned system, and the gas extraction method comprises:

[0044] (S1) passing the gas extraction pipe through the central tube of the support assembly followed by insertion into the borehole; mounting the fixing device onto the extraction end of the gas extraction pipe; activating the four drive motors to drive the four horizontal screws and the four vertical screws to extend out of the square housing, such that first bracing claws and second bracing claws abut against an inner wall of the borehole to secure the gas extraction pipe; passing the first sealing water bag and the second sealing water bag connected to the water injection pipe through gaps within the support assembly and arranging the first sealing water bag and the second sealing water bag at the front end and the rear end of the support assembly, respectively; and arranging an end of the grouting pipe within a gap between the second sealing water bag and the support assembly;

[0045] (S2) activating the water injection and drainage device to inject water into the first sealing water bag and the second sealing water bag until a first preset pressure is reached to expand the first sealing water bag and the second sealing water bag for sealing; and closing the first valve on the water injection pipe and deactivating the water injection and drainage device;

[0046] (S3) opening the pressure valve on the grouting pipe and activating the grouting device to inject a non-solidifying sealing slurry into the sealing segment of the borehole; and closing the pressure valve and deactivating the grouting device until a second preset pressure is reached;

[0047] (S4) activating the gas extraction device to perform gas extraction, wherein the gas extraction device is provided with a gas concentration monitoring module; and when a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve on the grouting pipe, opening the pressure valve and activating the grouting device to perform grouting again until the second preset pressure is reached and an extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing;

[0048] (S5) after completion of gas extraction, opening the second valve on the slurry discharge pipe and activating the slurry discharge device to discharge the non-solidifying sealing slurry from the sealing segment, and opening the first valve on the water injection pipe and activating the water injection and drainage device to drain water from the first sealing water bag and the second sealing water bag; and

[0049] (S6) retrieving the first sealing water bag, the second sealing water bag, the water injection pipe, the grouting pipe and the slurry discharge pipe; engaging a hook rod with the engagement hole of the support assembly to take out the support assembly; activating the four drive motors to retract the four horizontal screws and the four vertical screws; and taking out the gas extraction pipe and the fixing device, followed by cleaning to enable recovery of the system.

[0050] Compared to the prior art, the present disclosure has the following beneficial effects.

[0051] This disclosure significantly improves sealing efficiency and borehole utilization in gas extraction process while ensuring reliable sealing performance.

[0052] (1) A Custom supporting structure combined with sealing water bags is employed. The central control unit synchronizes the grouting and gas extraction devices to maintain dynamic sealing throughout the gas extraction process.

[0053] (2) The central control unit controls the water drainage system, the slurry discharge device, and the hook rod, enabling full recovery of the system after use.

[0054] (3) A dedicated extraction pipe fixation mechanism stabilizes the pipe during operation, effectively preventing vibration-induced efficiency loss and excessive wear.

[0055] The method is simple to implement, easy to operate, highly reliable, and cost-effective, making it well-suited for widespread adoption in gas extraction boreholes across coal mines.BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 schematically shows a system for gas extraction based on a non-solidifying sealing material according to an embodiment of the present disclosure;

[0057] FIG. 2 schematically shows a support assembly according to an embodiment of the present disclosure;

[0058] FIG. 3 schematically shows a hook rod according to an embodiment of the present disclosure; and

[0059] FIG. 4 schematically shows a fixing device of a gas extraction pipe according to an embodiment of the present disclosure.

[0060] In the figures: 1—gas extraction pipe; 2—water injection pipe; 3—second sealing water bag; 4—frist valve; 5—water injection and drainage device; 6—gas extraction device; 7—central control unit; 8—grouting device; 9—pressure valve; 10—slurry discharge device; 11—second valve; 12—slurry discharge pipe; 13—grouting pipe; 14—support assembly; 15—outer support sleeve; 16—central tube; 17—support vertical plate; 18—engagement hole; 19—hook rod; 20—frist sealing water bag; 21—fixing device; 22—connecting pillar; 23—cylindrical inner tube; 24—fixing claw; 25—drive motor; 26—vertical gear; 27—horizontal gear; 28—horizontal screw; 29—vertical screw; 30—second bracing claw; 31—square housing; and 32—first bracing claw.DETAILED DESCRIPTION OF EMBODIMENTS

[0061] The present disclosure will be further illustrated in combination with the embodiments.Embodiment 1

[0062] Referring to FIG. 1, a system for gas extraction based on a non-solidifying sealing material includes a support assembly 14, a gas extraction pipe 1, a gas extraction device 6, a first sealing water bag 20, a second sealing water bag 3, a water injection and drainage device 5, a grouting device 8, a slurry discharge device 10 and a central control unit 7.

[0063] The support assembly 14 is arranged at a middle of a sealing segment of a borehole, and is configured to support the borehole. Referring to FIG. 2, the support assembly 14 includes an outer support sleeve 15. A central tube 16 is arranged along a central axis of the outer support sleeve 15. A plurality of support vertical plates 17 are fixedly connected to an interior of the outer support sleeve 15, and those among the plurality of support vertical plates 17 arranged between the outer support sleeve 15 and an outer wall of the central tube 16 are each provided with an engagement hole 18. The support assembly 14 is provided with a hook rod 19.

[0064] Referring to FIG. 3, during the retraction of the support assembly 14, the hook rod 19 is operated through a robotic arm controlled via the central control unit 7. A size of the support assembly 14 is set according to a diameter of the borehole. The support assembly 14 can be arranged in the sealing segment or other segments of the borehole for supporting.

[0065] The gas extraction pipe 1 is configured to pass through the central tube 16, and is located at a center of the borehole. The gas extraction pipe 1 is configured for gas extraction. The gas extraction device 6 is connected to an end of the gas extraction pipe 1, and is provided with a gas concentration monitoring module. The gas concentration monitoring module is configured to monitor gas extraction concentration during the gas extraction.

[0066] The first sealing water bag 20 is arranged at a front end of the support assembly 14, and the second sealing water bag 3 is arranged at a rear end of the support assembly 14.

[0067] The water injection and drainage device 5 is connected to a water injection pipe 2. An end of the water injection pipe 2 is connected to the first sealing water bag 20 and the second sealing water bag 3. The water injection pipe 2 is provided with a first valve 4. The first valve 4 is configured for water injection and drainage of the first sealing water bag 20 and the second sealing water bag 3.

[0068] The grouting device 8 is connected to a grouting pipe 13 extending into the sealing segment. The grouting pipe 13 is provided with a pressure valve 9. A non-solidifying sealing material with a preset pressure is injected into the sealing segment through the grouting pipe 13. The pressure valve 9 is configured to monitor a pressure of the sealing segment. When the pressure and the gas extraction concentration decrease, the pressure valve 9 automatically opens, such that the grouting device 8 inject a slurry into the sealing segment until the preset pressure is reached. At that point, the sealing is completed and the pressure valve 9 closes.

[0069] The slurry discharge device 10 is connected to a slurry discharge pipe 12 extending into the sealing segment. The slurry discharge pipe 12 is provided with a second valve 11 to discharge and recycle the non-solidifying sealing material after use.

[0070] The central control unit 7 is electrically connected to the water injection and drainage device 5, the gas extraction device 6, the grouting device 8, the slurry discharge device 10, the first valve 4, the pressure valve 9 and the second valve 11, and is configured to control the water injection and drainage device 5, the gas extraction device 6, the grouting device 8, the slurry discharge device 10, the first valve 4, the pressure valve 9 and the second valve 11. The aforementioned components are integrally controlled by the central control unit 7, and are operated in conjunction.Embodiment 2

[0071] In this embodiment, an extraction end of the gas extraction pipe 1 is sleeved with a fixing device 21.

[0072] Referring to FIG. 4, the fixing device 21 includes a square housing 31, a cylindrical inner tube 23, a plurality of fixing claws 24, a drive mechanism, four horizontal screws 28 and four vertical screws 29. The cylindrical inner tube 23 is fixed inside the square housing 31. A plurality of connecting pillars 22 are fixedly connected between an outer wall of the cylindrical inner tube 23 and an inner wall of the square housing 31. The plurality of fixing claws 24 are uniformly arranged at an inner periphery of the cylindrical inner tube 23.

[0073] The drive mechanism includes four drive motors 25. The four drive motors 25 are arranged inside the square housing 31, and are electrically connected to the central control unit 7. An output shaft of each of the four drive motors 25 is provided with a vertical gear 26. The vertical gear 26 is engaged with a horizontal gear 27. Output shafts of two of the four drive motors 25 face toward a first side wall of the square housing 31. Output shafts of the other two of four drive motors 25 face toward a second side wall of the square housing 31.

[0074] Two of the four horizontal screws 28 are arranged on the first side wall of the square housing 31. The other two of the four horizontal screws 28 are arranged on the second side wall of the square housing 31. A first end of each of the four horizontal screws 28 is configured to extend out of the square housing 31, and is fixedly connected to a first bracing claw 32. A second end of each of the four horizontal screws 28 is arranged inside the square housing, and is engaged with the horizontal gear 27.

[0075] Two of the four vertical screws 29 are arranged on an upper side wall of the square housing 31. The other two of the four vertical screws 29 are arranged on a lower side wall of the square housing 31. A first end of each of the four vertical screws 29 is configured to extend out of the square housing 31, and is fixedly connected to a second bracing claw 30. A second end of each of the four vertical screws 29 is engaged with the vertical gear 26.

[0076] The fixing device 21 is configured to fix the gas extraction pipe 1 and prevent its vibration. The fixing device 21 is connected to the end of the gas extraction pipe 1. The central control unit 7 is connected to a control wire to control the drive motor 25 to rotate, thereby controlling the vertical gear 26 to rotate. The vertical gear 26 is engaged with the horizontal gear 27 and each of the four vertical screws 29, driving them to rotate. The horizontal gear 27 is engaged with each of the four horizontal screws 28, driving it to rotate. The rotations of the four horizontal screws 28 and the four vertical screws 29 enable extension and retraction functions. The second bracing claw 30 contacts a wall of the borehole to secure the square housing 31. The square housing 31 is connected to the cylindrical inner tube 23 via the plurality of connecting pillars 22. The cylindrical inner tube 23 has the fixing claw 24, which attaches to the end of the gas extraction pipe 1, thus securing the gas extraction pipe 1.Embodiment 3

[0077] In this embodiment, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction method is performed using the system in the embodiment 1, and is performed through the following steps.

[0078] (S1) The gas extraction pipe 1 passes through the central tube 16 of the support assembly 14 followed by insertion into the borehole. The first sealing water bag 20 and the second sealing water bag 3 connected to the water injection pipe 2 pass through gaps within the support assembly 14, where the water injection pipe 2 is configured to pass through a gap between the outer support sleeve 15 of the support assembly 14 and the plurality of support vertical plates 17, and the gas extraction pipe 1 is configured to pass through a gap within the central tube 16 of the support assembly 14. The first sealing water bag 20 and the second sealing water bag 3 are arranged at the front end and the rear end of the support assembly 14, respectively. An end of the grouting pipe 13 is arranged within a gap between the second sealing water bag 3 and the support assembly 14.

[0079] (S2) The water injection and drainage device 5 is activated to inject water into the first sealing water bag 20 and the second sealing water bag 3 until a first preset pressure is reached to expand the first sealing water bag 20 and the second sealing water bag 3 for sealing. The first valve 4 on the water injection pipe 2 is closed, and the water injection and drainage device 5 is deactivated.

[0080] (S3) The pressure valve 9 on the grouting pipe 13 is opened, and the grouting device 8 is activated to inject the non-solidifying sealing slurry into the sealing segment of the borehole. The pressure valve 9 is closed and the grouting device 8 is deactivated until a second preset pressure is reached.

[0081] (S4) The gas extraction device 6 is activated to perform gas extraction, where the gas extraction device 6 is provided with a gas concentration monitoring module. When a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve 9 on the grouting pipe 13, the pressure valve 9 is opened and the grouting device 8 is activated to perform grouting again until the second preset pressure is reached and a current extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing.

[0082] (S5) After completion of gas extraction, the second valve 11 on the slurry discharge pipe 12 is opened, and the slurry discharge device 10 is activated to discharge the non-solidifying sealing slurry from the sealing segment. The first valve 4 on the water injection pipe 2 is opened and the water injection and drainage device 5 is activated to drain water from the first sealing water bag 20 and the second sealing water bag 3.

[0083] (S6) The first sealing water bag 20, the second sealing water bag 3, the water injection pipe 2, the grouting pipe 13 and the slurry discharge pipe 12 are retrieved. The hook rod 19 is engaged with the engagement hole 18 of the support assembly 14 to sequentially take out the support assembly 14 and the gas extraction pipe 1. All components of the system are cleaned to enable recovery.Embodiment 4

[0084] In this embodiment, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction is performed using the system in the embodiment 2, and is performed through the following steps.

[0085] (a) The gas extraction pipe 1 passes through the central tube 16 of the support assembly 14 followed by insertion into the borehole. The fixing device 21 is mounted onto the extraction end of the gas extraction pipe 1. The four drive motors 25 are activated to drive the four horizontal screws 28 and the four vertical screws 29 to extend out of the square housing 31, such that first bracing claws 32 and second bracing claws 30 abut against an inner wall of the borehole to secure the gas extraction pipe 1. The first sealing water bag 20 and the second sealing water bag 3 connected to the water injection pipe 2 pass through gaps within the support assembly 14, where the water injection pipe 2 is configured to pass through a gap between the outer support sleeve 15 of the support assembly 14 and the plurality of support vertical plates 17, and the gas extraction pipe 1 is configured to pass through a gap within the central tube 16 of the support assembly 14. The first sealing water bag 20 and the second sealing water bag 3 are arranged at the front end and the rear end of the support assembly 14, respectively. An end of the grouting pipe 13 is arranged within a gap between the second sealing water bag 3 and the support assembly 14.

[0086] (b) The water injection and drainage device 5 is activated to inject water into the first sealing water bag 20 and the second sealing water bag 3 until a first preset pressure is reached to expand the first sealing water bag 20 and the second sealing water bag 3 for sealing. The first valve 4 on the water injection pipe 2 is closed, and the water injection and drainage device 5 is deactivated.

[0087] (c) The pressure valve 9 on the grouting pipe 13 is opened, and the grouting device 8 is activated to inject the non-solidifying sealing slurry into the sealing segment of the borehole. The pressure valve 9 is closed and the grouting device 8 is deactivated until a second preset pressure is reached.

[0088] (d) The gas extraction device 6 is activated to perform gas extraction, where the gas extraction device 6 is provided with a gas concentration monitoring module. When a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve 9 on the grouting pipe 13, the pressure valve 9 is opened and the grouting device 8 is deactivated to perform grouting again until the second preset pressure is reached and an extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing.

[0089] (e) After completion of gas extraction, the second valve 11 on the slurry discharge pipe 12 is opened, and the slurry discharge device 10 is activated to discharge the non-solidifying sealing slurry from the sealing segment. The first valve 4 on the water injection pipe 2 is opened and the water injection and drainage device 5 is activated to drain water from the first sealing water bag 20 and the second sealing water bag 3.

[0090] (f) The first sealing water bag 20, the second sealing water bag 3, the water injection pipe 2, the grouting pipe 13 and the slurry discharge pipe 12 are retrieved. The hook rod 19 is engaged with the engagement hole 18 of the support assembly 14 to take out the support assembly 14. The four drive motors 25 are activated to retract the four horizontal screws 28 and the four vertical screws 29. The gas extraction pipe 1 and the fixing device 21 are taken out, followed by cleaning to enable recovery of the system.

[0091] It should be noted that the embodiments described above are merely illustrative, and are not intended to limit the present disclosure. For those skilled in the art, any modifications can be made to this disclosure in forms and details without paying creative labor, and shall fall within the scope of the disclosure defined by the appended claims.

Examples

embodiment 1

[0062]Referring to FIG. 1, a system for gas extraction based on a non-solidifying sealing material includes a support assembly 14, a gas extraction pipe 1, a gas extraction device 6, a first sealing water bag 20, a second sealing water bag 3, a water injection and drainage device 5, a grouting device 8, a slurry discharge device 10 and a central control unit 7.

[0063]The support assembly 14 is arranged at a middle of a sealing segment of a borehole, and is configured to support the borehole. Referring to FIG. 2, the support assembly 14 includes an outer support sleeve 15. A central tube 16 is arranged along a central axis of the outer support sleeve 15. A plurality of support vertical plates 17 are fixedly connected to an interior of the outer support sleeve 15, and those among the plurality of support vertical plates 17 arranged between the outer support sleeve 15 and an outer wall of the central tube 16 are each provided with an engagement hole 18. The support assembly 14 is provid...

embodiment 2

[0071]In this embodiment, an extraction end of the gas extraction pipe 1 is sleeved with a fixing device 21.

[0072]Referring to FIG. 4, the fixing device 21 includes a square housing 31, a cylindrical inner tube 23, a plurality of fixing claws 24, a drive mechanism, four horizontal screws 28 and four vertical screws 29. The cylindrical inner tube 23 is fixed inside the square housing 31. A plurality of connecting pillars 22 are fixedly connected between an outer wall of the cylindrical inner tube 23 and an inner wall of the square housing 31. The plurality of fixing claws 24 are uniformly arranged at an inner periphery of the cylindrical inner tube 23.

[0073]The drive mechanism includes four drive motors 25. The four drive motors 25 are arranged inside the square housing 31, and are electrically connected to the central control unit 7. An output shaft of each of the four drive motors 25 is provided with a vertical gear 26. The vertical gear 26 is engaged with a horizontal gear 27. Out...

embodiment 3

[0077]In this embodiment, the present disclosure provides a gas extraction method based on a non-solidifying sealing material, where the gas extraction method is performed using the system in the embodiment 1, and is performed through the following steps.[0078](S1) The gas extraction pipe 1 passes through the central tube 16 of the support assembly 14 followed by insertion into the borehole. The first sealing water bag 20 and the second sealing water bag 3 connected to the water injection pipe 2 pass through gaps within the support assembly 14, where the water injection pipe 2 is configured to pass through a gap between the outer support sleeve 15 of the support assembly 14 and the plurality of support vertical plates 17, and the gas extraction pipe 1 is configured to pass through a gap within the central tube 16 of the support assembly 14. The first sealing water bag 20 and the second sealing water bag 3 are arranged at the front end and the rear end of the support assembly 14, res...

Claims

1. A system for gas extraction based on a non-solidifying sealing material, comprising:a support assembly;a gas extraction pipe;a gas extraction device;a first sealing water bag;a second sealing water bag;a water injection and drainage device;a grouting device;a slurry discharge device; anda central control unit;wherein the support assembly is arranged at a middle of a sealing segment of a borehole; the support assembly comprises an outer support sleeve; a central tube is arranged along a central axis of the outer support sleeve; a plurality of support vertical plates are fixedly connected to an interior of the outer support sleeve; and those among the plurality of support vertical plates arranged between the outer support sleeve and an outer wall of the central tube are each provided with an engagement hole;the gas extraction pipe is configured to pass through the central tube, and is located at a center of the borehole;the gas extraction device is connected to a first end of the gas extraction pipe;the first sealing water bag is arranged at a front end of the support assembly, and the second sealing water bag is arranged at a rear end of the support assembly;the water injection and drainage device is connected to a water injection pipe; an end of the water injection pipe is connected to the first sealing water bag and the second sealing water bag; and the water injection pipe is provided with a first valve;the grouting device is connected to a grouting pipe extending into the sealing segment; and the grouting pipe is provided with a pressure valve;the slurry discharge device is connected to a slurry discharge pipe extending into the sealing segment; and the slurry discharge pipe is provided with a second valve; andthe central control unit is electrically connected to the water injection and drainage device, the gas extraction device, the grouting device, the slurry discharge device, the first valve, the pressure valve and the second valve, and is configured to control the water injection and drainage device, the gas extraction device, the grouting device, the slurry discharge device, the first valve, the pressure valve and the second valve.

2. The system of claim 1, wherein a second end of the gas extraction pipe is configured as an extraction end, and is sleeved with a fixing device;the fixing device comprises a square housing, a cylindrical inner tube, a plurality of fixing claws, a drive mechanism, four horizontal screws and four vertical screws;the cylindrical inner tube is fixed inside the square housing;a plurality of connecting pillars are fixedly connected between an outer wall of the cylindrical inner tube and an inner wall of the square housing;the plurality of fixing claws are uniformly arranged at an inner periphery of the cylindrical inner tube;the drive mechanism comprises four drive motors; the four drive motors are arranged inside the square housing, and are electrically connected to the central control unit; an output shaft of each of the four drive motors is provided with a vertical gear;the vertical gear is engaged with a horizontal gear; output shafts of two of the four drive motors face toward a first side wall of the square housing; and output shafts of the other two of four drive motors face toward a second side wall of the square housing;two of the four horizontal screws are arranged on the first side wall of the square housing, and the other two of the four horizontal screws are arranged on the second side wall of the square housing; a first end of each of the four horizontal screws is configured to extend out of the square housing, and is fixedly connected to a first bracing claw; anda second end of each of the four horizontal screws is arranged inside the square housing, and is engaged with the horizontal gear; andtwo of the four vertical screws are arranged on an upper wall of the square housing, and the other two of the four vertical screws are arranged on a lower wall of the square housing; a first end of each of the four vertical screws is configured to extend out of the square housing, and is fixedly connected to a second bracing claw; and a second end of each of the four vertical screws is engaged with the vertical gear.

3. A gas extraction method based on a non-solidifying sealing material, the gas extraction method being performed using the system of claim 1, and the gas extraction method comprising:(S1) passing the gas extraction pipe through the central tube of the support assembly followed by insertion into the borehole; passing the first sealing water bag and the second sealing water bag connected to the water extraction pipe through gaps within the support assembly, and arranging the first sealing water bag and the second sealing water bag at the front end and the rear end of the support assembly, respectively; andarranging an end of the grouting pipe within a gap between the second sealing water bag and the support assembly;(S2) activating the water injection and drainage device to inject water into the first sealing water bag and the second sealing water bag until a first preset pressure is reached to expand the first sealing water bag and the second sealing water bag for sealing; and closing the first valve on the water injection pipe and deactivating the water injection and drainage device;(S3) opening the pressure valve on the grouting pipe, and activating the grouting device to inject a non-solidifying sealing slurry into the sealing segment of the borehole; and closing the pressure valve and deactivating the grouting device until a second preset pressure is reached;(S4) activating the gas extraction device to perform gas extraction, wherein the gas extraction device is provided with a gas concentration monitoring module; and when a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve on the grouting pipe, opening the pressure valve and activating the grouting device to perform grouting again until the second preset pressure is reached and a current extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing;(S5) after completion of gas extraction, opening the second valve on the slurry discharge pipe, and activating the slurry discharge device to discharge the non-solidifying sealing slurry from the sealing segment; opening the first valve on the water injection pipe and activating the water injection and drainage device to drain water from the first sealing water bag and the second sealing water bag; and(S6) retrieving the first sealing water bag, the second sealing water bag, the water injection pipe, the grouting pipe and the slurry discharge pipe; engaging a hook rod with the engagement hole of the support assembly to sequentially take out the support assembly and the gas extraction pipe; and cleaning all components of the system to enable recovery.

4. A gas extraction method based on a non-solidifying sealing material, the gas extraction method being performed using the system of claim 2, and the gas extraction method comprising:(S1) passing the gas extraction pipe through the central tube of the support assembly followed by insertion into the borehole; mounting the fixing device onto the extraction end of the gas extraction pipe; activating the four drive motors to drive the four horizontal screws and the four vertical screws to extend out of the square housing, such that first bracing claws and second bracing claws abut against an inner wall of the borehole to secure the gas extraction pipe; passing the first sealing water bag and the second sealing water bag connected to the water injection pipe through gaps within the support assembly and arranging the first sealing water bag and the second sealing water bag at the front end and the rear end of the support assembly, respectively; and arranging an end of the grouting pipe within a gap between the second sealing water bag and the support assembly;(S2) activating the water injection and drainage device to inject water into the first sealing water bag and the second sealing water bag until a first preset pressure is reached to expand the first sealing water bag and the second sealing water bag for sealing; andclosing the first valve on the water injection pipe and deactivating the water injection and drainage device;(S3) opening the pressure valve on the grouting pipe and activating the grouting device to inject a non-solidifying sealing slurry into the sealing segment of the borehole;and closing the pressure valve and deactivating the grouting device until a second preset pressure is reached;(S4) activating the gas extraction device to perform gas extraction, wherein the gas extraction device is provided with a gas concentration monitoring module; and when a decline in gas concentration is detected, and a decrease in slurry concentration within the sealing segment is also detected by the pressure valve on the grouting pipe, opening the pressure valve and activating the grouting device to perform grouting again until the second preset pressure is reached and an extraction concentration reaches 80% of an initial extraction concentration, so as to achieve dynamic sealing;(S5) after completion of gas extraction, opening the second valve on the slurry discharge pipe and activating the slurry discharge device to discharge the non-solidifying sealing slurry from the sealing segment, and opening the first valve on the water injection pipe and activating the water injection and drainage device to drain water from the first sealing water bag and the second sealing water bag; and(S6) retrieving the first sealing water bag, the second sealing water bag, the water injection pipe, the grouting pipe and the slurry discharge pipe; engaging a hook rod with the engagement hole of the support assembly to take out the support assembly;activating the four drive motors to retract the four horizontal screws and the four vertical screws; and taking out the gas extraction pipe and the fixing device, followed by cleaning to enable recovery of the system.

Images