A coal mine underground hydraulic fracturing borehole sealing device and a use method thereof

Abstract

The present application relates to coal mine gas extraction device technical field, specifically is a kind of coal mine underground hydraulic fracturing borehole hole sealing device and its use method.The present application includes connector, the connector includes fixed communication mechanism, hole sealing mechanism and sealing mechanism.The present application is provided with air bag, baffle ring and rubber ring, when connecting pipe moves to the inside of connector, connecting pipe extrudes rubber ring and moves and compresses rigid spring, so that rigid spring extrudes rubber ring and connecting pipe is in close contact, and preliminary closure is carried out;While rubber ring is compressed by connecting rod to promote extrusion plate hydraulic oil in the inside of hydraulic oil cavity, and the air bag at the both ends of hydraulic oil is extruded to expand, to promote the gap between connecting pipe and connector is sealed again;Cavity ring drives baffle ring and connector to close contact, and finally sealed.By injecting water and other medium, coal seam is fractured, and subsequent gas extraction work can be carried out.

Description

Technical Field

[0001] This invention relates to the technical field of coal mine gas extraction devices, specifically a coal mine underground hydraulic fracturing borehole sealing device and its usage method. Background Technology

[0002] Hydraulic fracturing technology is widely used in the extraction of gas from low-permeability coal seams in underground coal mines. It can effectively expand the pressure relief range of the coal seam, increase its permeability, and increase the amount of gas extracted from boreholes. Simultaneously, the gas emission and coal dust generation are reduced during mining of the fracturing, moist coal seam. Therefore, hydraulic fracturing technology provides an effective approach for the treatment of high-gas, low-permeability coal seams.

[0003] Unlike surface hydraulic fracturing for oil and gas resources, which relies on the weight of the slurry in hundreds or even thousands of meters of drilling to achieve borehole sealing, underground hydraulic fracturing in coal mines is hampered by factors such as poor borehole wall smoothness, short borehole sealing length, and defects in the sealing device itself. In existing technologies, when high-pressure water or other media are injected to fracturing the coal seam, leakage of water or other media from between the sealing devices is common, leading to borehole water leakage, fracturing hole failure, and directly affecting the pressure relief and permeability enhancement effect of the coal seam, as well as subsequent gas extraction work. This severely restricts the practice and application of hydraulic fracturing technology in underground coal mines. Summary of the Invention

[0004] The purpose of this invention is to provide a sealing device for hydraulic fracturing boreholes in coal mines and its usage method, so as to solve the problems mentioned in the background art.

[0005] The objective of this invention can be achieved through the following technical solution: a sealing device for hydraulic fracturing boreholes in coal mines, comprising a connector, wherein the connector comprises a fixing and connecting mechanism, a sealing mechanism and a sealing mechanism.

[0006] The sealing mechanism includes a hydraulic oil chamber, an air bladder, and a retaining ring. The connector has a hydraulic oil chamber inside, and two ends of the hydraulic oil chamber are movably sleeved with extrusion plates. A connecting rod is fixed to the side of the extrusion plate. One end of the connecting rod passes through the connector and is fixed with a rubber ring. A sleeve that movably sleeves with the connector is fixed inside the rubber ring. A rigid spring located between the side of the rubber ring and the inner wall of the connector is movably sleeved on the outer surface of the connecting rod. Air bladders are installed at both ends of the connector, and the retaining ring is installed on the fixed communication mechanism.

[0007] Preferably, the sealing mechanism includes two connecting tubes connected to the connector, and the two connecting tubes are fixedly connected to the first sealing device and the second sealing device, respectively.

[0008] Preferably, the fixed communication mechanism includes a driving component, a telescopic component, and a fixing component.

[0009] The fixing component includes a pin assembly, a spring-back assembly, and a limiting assembly.

[0010] The pin assembly includes a cavity ring and a round head hole. The cavity ring is sleeved on the connecting pipe, and the round head hole is opened on the connecting pipe. The cavity ring is movably sleeved with symmetrically distributed round head rods. The outer surface of the round head rods is movably sleeved with the inner wall of the round head hole. The side of the cavity ring is fixedly connected to the retaining ring.

[0011] Preferably, the rebound assembly includes a side plate, a side plate is fixed on the round-headed rod, a flexible spring is fixed on the side plate, and the end of the flexible spring is fixed to the inner wall of the cavity ring.

[0012] Preferably, the limiting component includes a plug rod, a through hole, a fixing hole, and a insertion hole. The connector has symmetrically distributed plug rods fixed on it, the cavity ring has a through hole, the round-headed rod has a fixing hole, and the connecting tube has an insertion hole. The plug rod, through hole, fixing hole, and insertion hole correspond to each other.

[0013] Preferably, the telescopic component includes a square cavity, the inside of the screw hole rod has a square cavity, a square block is movably sleeved inside the square cavity, a round rod is fixed to the side of the square block, and the end of the round rod passes through the screw hole rod and is fixed to the cavity ring.

[0014] Preferably, it also includes a sealing and blocking protection mechanism.

[0015] The sealing and blocking protection mechanism includes a sealing component and a blocking and protection component.

[0016] The sealing assembly includes an injection tube, an expansion tube, a side groove, and an injection hole. The first and second sealing devices are both fixed with injection tubes and expansion tubes. The interiors of the first and second sealing devices are provided with annular equidistant side grooves and injection holes. The side grooves are connected to the expansion tubes through the injection holes.

[0017] Preferably, the blocking and protective assembly includes a stop block, a stop block is sleeved inside the side groove, a limit hole is opened inside the stop block, a side block is movably sleeved inside the limit hole, an inclined block is fixed to the side of the stop block, a fixing rod is fixed to the side of the side block, one end of the fixing rod passes through the inclined block and is fixed to the inner wall of the side groove, and a movable ring is fixed to the side of the stop block.

[0018] Preferably, a sleeve block that is movably connected to the expansion tube is fixed to the side of the movable ring, a rubber block is fixed to the side of the sleeve block, a return spring is fixed to the side block, and a fixing ring is fixed to the end of the return spring. There are two fixing rings, which are respectively fixed to the first sealing device and the second sealing device.

[0019] Preferably, a method for using a hydraulic fracturing borehole sealing device in a coal mine includes the following steps:

[0020] S1. First, press the cavity ring and insert the connecting tube on the first sealing device into the inside of the connector, so that the connecting tube pushes the round head rod to move and the side plate compresses the flexible spring. When the round head rod corresponds to the round head hole, the flexible spring squeezes the round head rod through the side plate, and then the round head rod moves into the inside of the round head hole.

[0021] S2. Then push the cavity ring, so that the round rod drives the block to move along the inner wall of the square cavity until the insertion rod passes through the through hole and is inserted into the inside of the fixing hole, so that the insertion rod fixes the round rod through the fixing hole. Then insert the connecting tube on the second sealing device into the inside of the connector in the same way.

[0022] S3. When the connecting tubes on the first and second sealing devices are both inserted into the connector, the dual-axis motor is started. The threaded rod drives the two cavity rings to move through the threaded hole rod. The cavity rings drive the connecting tubes to move into the connector and squeeze the rubber rings through the round head rods. The dual-axis motor is stopped when the cavity rings drive the retaining rings to make closed contact with the connector. At this time, the insertion rod is inserted into the insertion hole, which achieves the purpose of fixing and connecting the first and second sealing devices.

[0023] S4. Finally, the fixed first and second sealing devices are sent into the borehole of the coal seam through the drilling device. Water and other media are injected into the first and second sealing devices through the high-pressure water injection pump. After the first and second sealing devices expand, they seal the borehole. Continue to inject water and other media to increase the pressure inside the borehole and then fracture the coal seam. After that, the subsequent gas extraction work can be carried out.

[0024] The beneficial effects of this invention are:

[0025] 1. This invention, by setting up airbags, retaining rings, and rubber rings, allows the connecting pipe to move into the connector by squeezing the rubber ring and compressing the rigid spring. This causes the rigid spring to compress the rubber ring and the connecting pipe into tight contact, achieving initial sealing. Simultaneously, the rubber ring, through the connecting rod, causes the squeezing plate to compress the hydraulic oil inside the hydraulic oil chamber. The hydraulic oil then compresses the airbags at both ends of the connector, causing them to expand and further seal the gap between the connecting pipe and the connector. Finally, the cavity ring drives the retaining ring to make closed contact with the connector, achieving a final seal. This achieves the purpose of sealing the borehole sealing device and ensures the subsequent gas extraction work.

[0026] 2. This invention, by setting up a threaded rod, a threaded hole rod, and a round-headed rod, allows the connecting tube on the first or second sealing device to be inserted into the connector by pressing the cavity ring. When the round-headed rod aligns with the round-headed hole, a flexible spring compresses the round-headed rod through the side plate, causing it to move into the round-headed hole. Then, the cavity ring is pushed until the insertion rod passes through the through hole and is inserted into the fixing hole, thus fixing the round-headed rod through the fixing hole. The dual-axis motor is then started, and the threaded rod drives the two cavity rings to move through the threaded hole rod. The cavity rings, in turn, drive the two connecting tubes to move into the connector through the round-headed rod until the first and second sealing devices are fixedly connected, thus achieving the purpose of facilitating the fixing, disassembly, and connection of the first and second sealing devices.

[0027] 3. This invention, by setting up an inclined block, a return spring, and a sleeve block, injects media such as water into the first and second sealing devices through the injection pipe. The water and other media in the first and second sealing devices are then forced against the stop block by the inclined block until the inclined block releases its obstruction of the injection hole. Simultaneously, the side block moves the sleeve block to release its obstruction of the expansion hose and stretches the return spring, allowing the water and other media to sequentially enter the interior of the expansion hose through the side groove and injection pipe, causing the expansion hose to expand. Continued injection of water and other media increases the pressure inside the borehole, fracturing the coal seam. When the expansion hose is not in use, the return spring will pull the sleeve block through the moving ring to block the expansion hose, causing the sleeve block to press against the connecting pipe, thus achieving the purpose of blocking and protecting the expansion hose. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the connector structure of the present invention;

[0031] Figure 3 This is a front cross-sectional view of the connector of the present invention;

[0032] Figure 4 This is a side cross-sectional view of the cavity ring of the present invention;

[0033] Figure 5 This is a front cross-sectional view of the screw hole rod of the present invention;

[0034] Figure 6 This is a schematic diagram of the connecting pipe of the present invention;

[0035] Figure 7 This is a front cross-sectional view of the second sealing device of the present invention;

[0036] Figure 8 This is the present invention. Figure 2 A magnified view of the structure at point A in the middle;

[0037] Figure 9 This is the present invention. Figure 3 A magnified schematic diagram of the structure at point B in the middle.

[0038] In the diagram: 1. Connector; 2. First sealing device; 3. Second sealing device; 4. Connecting pipe; 5. Hydraulic oil chamber; 6. Airbag; 7. Extrusion plate; 8. Connecting rod; 9. Rigid spring; 10. Sleeve; 11. Dual-axis motor; 12. Threaded rod; 13. Threaded hole rod; 14. Square cavity; 15. Block; 16. Round rod; 17. Cavity ring; 18. Round head rod; 19. Side plate; 20. Flexible spring; 21. 1. Round head hole; 22. Insert rod; 23. Insertion hole; 24. Fixing hole; 25. Through hole; 26. Retaining ring; 27. Rubber ring; 28. Injection tube; 29. ​​Side groove; 30. Injection hole; 31. Expansion tube; 32. Inclined block; 33. Stop block; 34. Moving ring; 35. Return spring; 36. Sleeve block; 37. Fixing ring; 38. Rubber block; 39. Fixing rod; 40. Side block; 41. Limiting hole. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0040] A hydraulic fracturing borehole sealing device for coal mines is a type of gas extraction equipment within the resource utilization industry. It is used for the extraction and reuse of underground coal mine gas, improving the utilization rate of coal mine gas and other energy sources. Figures 1 to 9 As shown, it includes connector 1, which includes a fixed communication mechanism, a sealing mechanism, and a sealing mechanism;

[0041] The sealing mechanism includes a hydraulic oil chamber 5, an air bladder 6, and a retaining ring 26. The connector 1 has a hydraulic oil chamber 5 inside. The two ends of the hydraulic oil chamber 5 are movably sleeved with extrusion plates 7. A connecting rod 8 is fixed to the side of the extrusion plate 7. One end of the connecting rod 8 passes through the connector 1 and is fixed with a rubber ring 27. A sleeve 10 that is movably sleeved with the connector 1 is fixed inside the rubber ring 27. A rigid spring 9 located between the side of the rubber ring 27 and the inner wall of the connector 1 is movably sleeved on the outer surface of the connecting rod 8. Air bladders 6 are installed at both ends of the connector 1. The retaining ring 26 is installed on the fixed communication mechanism.

[0042] Through the design of the hydraulic oil chamber 5, air bladder 6, and retaining ring 26, when the fixing and connecting mechanism drives the sealing mechanism to insert into the connector 1 for fixed connection, the sealing mechanism squeezes the rubber ring 27 and sleeve 10 to move along the inner wall of the connector 1 and compress the rigid spring 9, so that the rigid spring 9 squeezes the rubber ring 27 into tight contact with the sealing mechanism for initial sealing; at the same time, the rubber ring 27, through the connecting rod 8, causes the squeezing plate 7 to compress the hydraulic oil inside the hydraulic oil chamber 5, and the hydraulic oil squeezes the air bladders 6 at both ends of the connector 1 to expand, and the expanded air bladders 6 re-seal the gap between the sealing mechanism and the connector 1; the fixing and connecting mechanism drives the retaining ring 26 to make closed contact with the connector 1 for final sealing. This design ensures that water or other media are not injected into the connector 1, avoiding affecting the normal use of the sealing mechanism and achieving the purpose of sealing the drilling and sealing device.

[0043] like Figure 1 As shown, the sealing mechanism includes two connecting pipes 4 connected to the connector 1. The two connecting pipes 4 are fixedly connected to the first sealing device 2 and the second sealing device 3, respectively.

[0044] Through the design of the connecting tube 4 and the first sealing device 2 and the second sealing device 3, the first sealing device 2 and the second sealing device 3 are fixedly connected to the connector 1 through the connecting tube 4 and used together.

[0045] like Figure 3 As shown, the fixed connection mechanism includes a drive component, a telescopic component, and a fixed component;

[0046] The fixing components include a pin assembly, a spring-back assembly, and a limiting assembly;

[0047] The pin assembly includes a cavity ring 17 and a round head hole 21. The cavity ring 17 is sleeved on the connecting pipe 4, and the round head hole 21 is opened on the connecting pipe 4. The cavity ring 17 is movably sleeved with symmetrically distributed round head rods 18. The outer surface of the round head rods 18 is movably sleeved with the inner wall of the round head hole 21. The side of the cavity ring 17 is fixedly connected to the retaining ring 26.

[0048] With the design of the round head rod 18 and the round head hole 21, when the operator pulls the connecting tube 4 outward from the connector 1, the round head hole 21 will squeeze the round head rod 18 out of the interior of the connecting tube 4 and cause the round head rod 18 to squeeze the spring-loaded component, so that the connecting tube 4 can be removed from the connector 1, thus achieving the purpose of removing the connecting tube 4.

[0049] like Figure 4 As shown, the rebound assembly includes a side plate 19, a round-headed rod 18 with the side plate 19 fixed on it, and a flexible spring 20 fixed on the side plate 19. The end of the flexible spring 20 is fixed to the inner wall of the cavity ring 17.

[0050] The design of the side plate 19 and the flexible spring 20 allows the flexible spring 20 to pull the round-headed rod 18 and the round-headed hole 21 more tightly through the side plate 19.

[0051] like Figure 2 , Figure 4 , Figure 6 and Figure 7 As shown, the limiting component includes a plug rod 22, a through hole 25, a fixing hole 24, and a socket 23. The connector 1 is fixed with symmetrically distributed plug rods 22. The cavity ring 17 has a through hole 25. The round-headed rod 18 has a fixing hole 24. The connecting tube 4 has a socket 23. The plug rod 22, the through hole 25, the fixing hole 24, and the socket 23 correspond to each other.

[0052] By designing the insertion rod 22 and the fixing hole 24, when the insertion rod 22 is inserted into the inner wall of the fixing hole 24, the insertion rod 22 fixes the round-head rod 18 through the fixing hole 24, so that the round-head rod 18 cannot come out of the inside of the round-head hole 21, thus achieving the purpose of fixing the round-head rod 18.

[0053] like Figure 3 As shown, the drive assembly includes a dual-axis motor 11, which is fixed on the connector 1. Both ends of the dual-axis motor 11 are respectively connected to threaded rods 12, and the outer surface of the threaded rods 12 is threaded with threaded hole rods 13 that are connected to the telescopic assembly.

[0054] By operating the dual-axis motor 11, the threaded rod 12 drives the telescopic components to move in opposite directions through the threaded rod 13, thus achieving the purpose of moving the telescopic components in opposite directions.

[0055] like Figure 4 As shown, the telescopic assembly includes a square cavity 14. The screw hole rod 13 has a square cavity 14 inside. A square block 15 is movably sleeved inside the square cavity 14. A round rod 16 is fixed to the side of the square block 15. The end of the round rod 16 passes through the screw hole rod 13 and is fixed to the cavity ring 17.

[0056] Through the design of the square cavity 14 and the square block 15, the cavity ring 17 can move left and right, so that the cavity ring 17 can move to the position of the through hole 25 and the fixing hole 24. The insertion rod 22 passes through the through hole 25 and is inserted into the interior of the fixing hole 24 to fix the round head rod 18.

[0057] like Figure 7 As shown, it also includes a sealing and blocking protection mechanism;

[0058] The sealing and blocking protection mechanism includes a sealing component and a blocking and protection component;

[0059] The sealing assembly includes an injection tube 28, an expansion tube 31, a side groove 29, and an injection hole 30. The injection tube 28 and the expansion tube 31 are fixed on the first sealing device 2 and the second sealing device 3. The interior of the first sealing device 2 and the second sealing device 3 is provided with annular equidistant side grooves 29 and injection holes 30. The side grooves 29 are connected to the expansion tube 31 through the injection holes 30.

[0060] Water and other media are injected into the first sealing device 2 and the second sealing device 3 through the injection pipe 28. The water and other media enter the expansion tube 31 through the side groove 29 and the injection pipe 28 in sequence, causing the expansion tube 31 to expand.

[0061] like Figure 7 As shown, the blocking and protective assembly includes a stop block 33. The stop block 33 is sleeved inside the side groove 29. A limit hole 41 is opened inside the stop block 33. A side block 40 is movably sleeved inside the limit hole 41. An inclined block 32 is fixed to the side of the stop block 33. A fixing rod 39 is fixed to the side of the side block 40. One end of the fixing rod 39 passes through the inclined block 32 and is fixed to the inner wall of the side groove 29. A moving ring 34 is fixed to the side of the stop block 33. A sleeve block 36 that is movably connected to the expansion tube 31 is fixed to the side of the moving ring 34. A rubber block 38 is fixed to the side of the sleeve block 36. A return spring 35 is fixed on the side block 40. A fixing ring 37 is fixed to the end of the return spring 35. There are two fixing rings 37. The two fixing rings 37 are respectively fixed to the first sealing device 2 and the second sealing device 3.

[0062] When the expansion hose 31 is not in use, the return spring 35 will pull the sleeve block 36 through the moving ring 34 to block the expansion hose 31, and cause the sleeve block 36 to drive the rubber block 38 to squeeze and contact the connecting pipe 4, thereby achieving the purpose of blocking and protecting the expansion hose 31.

[0063] A method for using a hydraulic fracturing borehole sealing device in a coal mine includes the following steps:

[0064] S1. First, press the cavity ring 17 and insert the connecting tube 4 on the first sealing device 2 into the inside of the connector 1, so that the connecting tube 4 pushes the round head rod 18 to move and the side plate 19 compresses the flexible spring 20. When the round head rod 18 corresponds to the round head hole 21, the flexible spring 20 squeezes the round head rod 18 through the side plate 19 and moves into the inside of the round head hole 21.

[0065] S2. Then push the cavity ring 17, so that the round rod 16 drives the block 15 to move along the inner wall of the square cavity 14 until the insertion rod 22 passes through the through hole 25 and is inserted into the fixing hole 24, so that the insertion rod 22 fixes the round rod 18 through the fixing hole 24. Then insert the connecting tube 4 on the second sealing device 3 into the connector 1 in the same way.

[0066] S3. When the connecting tubes 4 on the first sealing device 2 and the second sealing device 3 are both inserted into the connector 1, the dual-axis motor 11 is started. The threaded rod 12 drives the two cavity rings 17 to move through the threaded rod 13. The cavity rings 17 drive the connecting tubes 4 to move into the connector 1 through the round-headed rod 18 and squeeze the rubber ring 27 until the cavity rings 17 drive the retaining ring 26 to make closed contact with the connector 1. At this time, the dual-axis motor 11 is stopped. At this time, the insertion rod 22 is inserted into the insertion hole 23, which achieves the purpose of fixing and connecting the first sealing device 2 and the second sealing device 3.

[0067] S4. Finally, the fixed first sealing device 2 and second sealing device 3 are sent into the borehole of the coal seam through the drilling device. Water and other media are injected into the first sealing device 2 and the second sealing device 3 through the high-pressure water injection pump. After the first sealing device 2 and the second sealing device 3 expand, they seal the borehole. After the water and other media are injected to increase the pressure in the borehole, the coal seam is fracturing. Then the subsequent gas extraction work can be carried out.

[0068] Working principle:

[0069] First, press down on the cavity ring 17 and insert the connecting tube 4 on the first sealing device 2 into the connector 1. This causes the connecting tube 4 to push the round-headed rod 18 to move, and causes the side plate 19 to compress the flexible spring 20. When the round-headed rod 18 corresponds to the round-headed hole 21, the flexible spring 20, through the side plate 19, squeezes the round-headed rod 18 into the round-headed hole 21. Then, push the cavity ring 17, causing the round rod 16 to drive the block 15 to move along the inner wall of the square cavity 14 until the insertion rod 22 passes through the through hole 25 and is inserted into the fixing hole 24, so that the insertion rod 22 passes through the fixing hole. 24. Fix the round-headed rod 18, and then insert the connecting tube 4 on the second sealing device 3 into the connector 1 in the same way; when the connecting tubes 4 on the first sealing device 2 and the second sealing device 3 are both inserted into the connector 1, start the dual-axis motor 11, and the threaded rod 12 drives the two cavity rings 17 to move through the threaded hole rod 13. The cavity rings 17 drive the two connecting tubes 4 to move into the connector 1 through the round-headed rod 18 until the first sealing device 2 and the second sealing device 3 are fixedly connected and stop, thus achieving the purpose of fixing and connecting the first sealing device 2 and the second sealing device 3.

[0070] When the connecting pipe 4 moves into the connector 1, it compresses the rubber ring 27 and the sleeve 10, causing them to move along the inner wall of the connector 1 and compress the rigid spring 9. This causes the rigid spring 9 to compress the rubber ring 27 into close contact with the connecting pipe 4, achieving initial sealing. Simultaneously, the rubber ring 27, through the connecting rod 8, causes the compression plate 7 to compress the hydraulic oil inside the hydraulic oil chamber 5. The hydraulic oil compresses the air bladders 6 at both ends of the connector 1, causing them to expand. The expanded air bladders 6 then re-seal the gap between the connecting pipe 4 and the connector 1. Finally, the cavity ring 17 drives the retaining ring 26 into closed contact with the connector 1, achieving final sealing. This design prevents leakage when water or other media are injected into the connector 1, avoiding interference with the normal operation of the sealing mechanism and achieving the purpose of sealing the drilling and sealing device, thus ensuring subsequent gas extraction operations.

[0071] When it is necessary to disassemble the first sealing device 2 and the second sealing device 3, first start the dual-axis motor 11 to disengage the fixing hole 24 on the round-head rod 18 from the insertion rod 22; then the operator pulls the connecting tube 4 outward from the connector 1. At this time, the round-head hole 21 squeezes the round-head rod 18 out of the interior of the connecting tube 4, and causes the side plate 19 to squeeze the flexible spring 20; finally, the connecting tube 4 can be removed from the connector 1, thus facilitating the disassembly of the first sealing device 2 and the second sealing device 3.

[0072] The first and second sealing devices 2 and 3, after being fixed, are sent into the borehole of the coal seam using a drilling device. Then, a high-pressure water injection pump injects water and other media into the first and second sealing devices 2 and 3 through the injection pipe 28. The water and other media in the first and second sealing devices 2 and 3 are forced by the inclined block 32 to the stop block 33 until the inclined block 32 releases the obstruction of the injection hole 30. At the same time, the side block 40 moves the sleeve block 36 to release the obstruction of the expansion hose 31 and stretch the return spring 35. The fixing rod 39 limits the stop block 33 through the side block 40 and the limiting hole 41. Thus, the water and other media enter the interior of the expansion hose 31 through the side groove 29 and the injection pipe 28 in sequence. The expansion hose 31 expands. After the water and other media are injected to increase the pressure in the borehole, the coal seam is fractured. Then, the subsequent gas extraction work can be carried out.

[0073] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A coal mine underground hydraulic fracturing borehole sealing device, comprising a connector (1), characterized in that, The connector (1) comprises a fixed communication mechanism, a hole sealing mechanism and a sealing mechanism; The sealing mechanism comprises a hydraulic oil cavity (5), an air bag (6) and a blocking ring (26), the inside of the connector (1) is provided with the hydraulic oil cavity (5), both ends of the inside of the hydraulic oil cavity (5) are movably sleeved with an extrusion plate (7), the side of the extrusion plate (7) is fixedly provided with a connecting rod (8), one end of the connecting rod (8) penetrates through the connector (1) and is fixedly provided with a rubber ring (27), the inside of the rubber ring (27) is fixedly provided with a sleeve (10) movably sleeved with the connector (1), the outer surface of the connecting rod (8) is movably sleeved with a rigid spring (9) located between the side of the rubber ring (27) and the inner wall of the connector (1), both ends of the connector (1) are provided with the air bag (6), and the blocking ring (26) is installed on the fixed communication mechanism. The hole sealing mechanism comprises a connecting pipe (4) connected with the connector (1), the number of the connecting pipe (4) is two, and the two connecting pipes (4) are fixedly communicated with the first hole sealing device (2) and the second hole sealing device (3) respectively. The fixed communication mechanism comprises a driving assembly, a telescopic assembly and a fixed assembly. The fixed assembly comprises a bolt assembly, a rebound assembly and a limiting assembly. The bolt assembly comprises a cavity ring (17) and a round head hole (21), the cavity ring (17) is sleeved on the connecting pipe (4), the round head hole (21) is formed in the connecting pipe (4), the inside of the cavity ring (17) is movably sleeved with symmetrically distributed round head rods (18), the outer surface of the round head rod (18) is movably sleeved with the inner wall of the round head hole (21), and the side of the cavity ring (17) is fixedly connected with the blocking ring (26). The limiting assembly comprises an insertion rod (22), a perforation (25), a fixed hole (24) and an insertion hole (23), the insertion rod (22) is fixedly arranged on the connector (1) in a symmetrical manner, the perforation (25) is formed in the cavity ring (17), the fixed hole (24) is formed in the round head rod (18), and the insertion hole (23) is formed in the connecting pipe (4); the insertion rod (22), the perforation (25), the fixed hole (24) and the insertion hole (23) correspond to each other.

2. The coal mine underground hydraulic fracturing borehole sealing device according to claim 1, characterized in that, The telescopic assembly comprises a square cavity (14), the inside of the screw hole rod (13) is provided with the square cavity (14), the inside of the square cavity (14) is movably sleeved with a square block (15), the side of the square block (15) is fixedly provided with a round rod (16), and the end of the round rod (16) penetrates through the screw hole rod (13) and is fixed with the cavity ring (17).

3. The coal mine underground hydraulic fracturing borehole sealing device according to claim 1, characterized in that, The rebound assembly comprises a side plate (19), the side plate (19) is fixedly arranged on the round head rod (18), the side plate (19) is fixedly provided with a flexible spring (20), and the end of the flexible spring (20) is fixed with the inner wall of the cavity ring (17). The hole sealing mechanism further comprises a hole sealing blocking protection mechanism. The hole sealing blocking protection mechanism comprises a hole sealing assembly and a blocking protection assembly. The hole sealing assembly comprises a liquid injection pipe (28), an expansion rubber pipe (31), a side groove (29) and a liquid injection hole (30), the liquid injection pipe (28) and the expansion rubber pipe (31) are fixed on the first hole sealer (2) and the second hole sealer (3), the side groove (29) and the liquid injection hole (30) are arranged in the first hole sealer (2) and the second hole sealer (3) in a ring shape and at equal intervals, and the side groove (29) is communicated with the expansion rubber pipe (31) through the liquid injection hole (30).

4. The coal mine underground hydraulic fracturing borehole sealing device according to claim 3, characterized in that, The blocking protection assembly comprises a blocking block (33), the blocking block (33) is sleeved in the side groove (29), a limiting hole (41) is arranged in the blocking block (33), a side block (40) is movably sleeved in the limiting hole (41), an inclined block (32) is fixed to the side surface of the blocking block (33), a fixed rod (39) is fixed to the side surface of the side block (40), one end of the fixed rod (39) penetrates through the inclined block (32) and is fixed to the inner wall of the side groove (29), and a moving ring (34) is fixed to the side surface of the blocking block (33).

5. The coal mine underground hydraulic fracturing borehole sealing device according to claim 4, characterized in that, The side surface of the moving ring (34) is fixed with a sleeve block (36) movably connected with the expansion rubber pipe (31), the side surface of the sleeve block (36) is fixed with a rubber block (38), the side block (40) is fixed with a return spring (35), the end of the return spring (35) is fixed with a fixed ring (37), the number of the fixed rings (37) is two, and the two fixed rings (37) are fixed on the first hole sealer (2) and the second hole sealer (3) respectively.

6. The method of using a coal mine underground hydraulic fracturing borehole sealing device according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1, first, hold the cavity ring (17), insert the connecting pipe (4) on the first hole sealer (2) into the inside of the connector (1), so that the connecting pipe (4) drives the round head rod (18) to move, and the side plate (19) compresses the flexible spring (20), when the round head rod (18) corresponds to the round head hole (21), the flexible spring (20) extrudes the round head rod (18) through the side plate (19), and then the round head rod (18) moves into the inside of the round head hole (21); S2, then, push the cavity ring (17), so that the round rod (16) drives the square block (15) to move along the inner wall of the square cavity (14), until the inserting rod (22) passes through the perforation (25) and is inserted into the inside of the fixed hole (24), so that the inserting rod (22) fixes the round head rod (18) through the fixed hole (24), and then the connecting pipe (4) on the second hole sealer (3) is inserted into the inside of the connector (1) in the same way; S3, when the connecting pipes (4) on the first hole sealer (2) and the second hole sealer (3) are inserted into the inside of the connector (1), start the double-shaft motor (11), the threaded rod (12) drives the two cavity rings (17) to move through the screw hole rod (13), the cavity ring (17) drives the connecting pipe (4) to move to the inside of the connector (1) through the round head rod (18) and extrudes the rubber ring (27), until the cavity ring (17) drives the blocking ring (26) to be in close contact with the connector (1), stop the double-shaft motor (11), at this time, the inserting rod (22) is inserted into the inside of the insertion hole (23), and the purpose of fixing the communication between the first hole sealer (2) and the second hole sealer (3) is achieved. S4, finally, through the drilling device, the fixed first packer (2) and the second packer (3) are sent into the drill hole of the coal seam, water is injected into the first packer (2) and the second packer (3) through a high-pressure water injection pump, the first packer (2) and the second packer (3) are expanded to seal the drill hole, the coal seam is fractured after the pressure in the drill hole is increased by continuing to inject water, and then subsequent gas extraction work can be performed.

Images