Reusable hole sealer for gas extraction through-layer drilling in underground coal mines and its operation method

Abstract

A reusable sealer for gas extraction through-layer boreholes in underground coal mines and an operation method thereof, comprising a first expansion capsule and a second expansion capsule coaxially mounted on a gas extraction pipe, and also comprising a first liquid injection connecting pipe, a second liquid injection connecting pipe, an intermediate liquid injection connecting pipe, a first liquid injection inlet pipe and a second liquid injection inlet pipe all parallel to the gas extraction pipe; the first liquid injection connecting pipe is provided with a first liquid injection hole connected to the inner cavity of the first expansion capsule; the second liquid injection connecting pipe is provided with a second liquid injection hole connected to the inner cavity of the second expansion capsule; the intermediate liquid injection connecting pipe is provided with a pressure-bearing one-way valve; the second liquid injection inlet pipe is provided with a pressure gauge and a valve. The present invention has a scientific principle, a simple structure, and is easy to operate, and realizes the functions of monitoring the sealing pressure of the gas extraction drilling sealer, refilling the sealer when the sealing pressure is reduced to increase the sealing pressure, and the sealer can be recycled and reused after the gas extraction operation is completed, which can effectively realize the reuse of materials and reduce the sealing cost.

Description

Technical Field

[0001] The invention belongs to the technical field of gas extraction through boreholes in underground coal mines, and in particular relates to a reusable hole sealer for gas extraction through layer boreholes in underground coal mines and an operation method thereof. Background Art

[0002] The gas contained in coal seams is a clean and efficient energy source. It is also the main factor affecting coal mine disasters such as gas outburst and coal and gas outburst. With the continuous deepening of coal mining depth, the gas content in coal seams is increasing overall. Gas pre-extraction is the key to ensuring safe mining. The extraction borehole is the carrier of gas extraction. The tightness of the sealing hole and the sealing cost are directly related to the safety production of the mine and its economic benefits.

[0003] At present, the gas extraction drilling sealing technology used is mostly "two blocking and one injection", that is, plugging devices are set on both sides of the sealing section to fix the boundary of the sealing area, and then grouting is injected into the middle area to achieve sealing. This process takes a long time to seal the hole, consumes a lot of disposable materials, and is costly; it is impossible to replenish fluid for secondary sealing in the later stage, and the effective sealing time is short. In addition, the existing expansion capsules used for sealing have the following technical problems: since the outer circle and inner circle of the expansion capsule are both smooth surfaces, and the inner wall of the borehole is not smooth and flat, a large water pressure is required to achieve a good seal between the outer circle of the expansion capsule and the inner wall of the borehole, but excessive water pressure will cause the expansion capsule to burst. Therefore, it is necessary to design a corresponding sealing and pressure-bearing structure without increasing the thickness of the expansion capsule. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a reusable sealer for gas extraction drilling holes in underground coal mines, which has good sealing effect, high pressure bearing capacity, convenient disassembly and assembly, and high construction efficiency, and an operating method thereof.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: a reusable sealer for gas extraction through-layer drilling in underground coal mines and an operation method thereof, comprising a first expansion capsule and a second expansion capsule coaxially installed on a gas extraction pipe, the gas extraction pipe is vertically arranged, the first expansion capsule is located above the second expansion capsule, the first expansion capsule and the second expansion capsule are cylindrical in shape and have a cylindrical hole along the center line that is sleeved on the outer circle of the gas extraction pipe, and also include a first liquid injection connecting pipe, a second liquid injection connecting pipe, an intermediate liquid injection connecting pipe, a first liquid injection inlet pipe and a second liquid injection inlet pipe that are all parallel to the gas extraction pipe;

[0006] The first liquid injection connecting tube is inserted into the first expansion capsule, the upper end of the first liquid injection connecting tube extends upward from the upper end surface of the first expansion capsule and is provided with a plug, the lower end of the first liquid injection connecting tube extends downward from the lower end surface of the first expansion capsule, and the first liquid injection connecting tube is provided with a first liquid injection hole communicating with the inner cavity of the first expansion capsule;

[0007] The second liquid injection connecting tube is inserted into the second expansion capsule, the upper end of the second liquid injection connecting tube extends upward from the upper end surface of the second expansion capsule, the lower end of the second liquid injection connecting tube extends downward from the lower end surface of the second expansion capsule, and the second liquid injection connecting tube is provided with a second liquid injection hole communicating with the inner cavity of the second expansion capsule;

[0008] The upper port of the intermediate liquid injection connecting pipe is connected to the lower port of the first liquid injection connecting pipe through a first quick-plug connector, the lower port of the intermediate liquid injection connecting pipe is connected to the upper port of the second liquid injection connecting pipe through a second quick-plug connector, and a pressure-bearing one-way valve is provided on the intermediate liquid injection connecting pipe;

[0009] The upper port of the first liquid injection inlet pipe is connected to the lower port of the second liquid injection connecting pipe through a third quick-plug connector, a three-way connector is provided between the lower port of the first liquid injection inlet pipe and the upper port of the second liquid injection inlet pipe, a pressure gauge is provided on the third interface of the three-way connector, and a valve is provided at the upper end of the second liquid injection inlet pipe.

[0010] The outer circles of the first expansion capsule and the second expansion capsule are provided with a convex sealing structure.

[0011] The raised sealing structure includes a plurality of annular convex sealing strips, all of which are evenly spaced along the center line of the expansion capsule. The cross section of each convex sealing strip is a semicircular structure, and the convex sealing strip and the expansion capsule are made of an integrated structure.

[0012] The first expansion capsule and the second expansion capsule are both provided with end surface pressure-bearing reinforcement structures on upper and lower end planes.

[0013] The end face pressure-bearing reinforcement structure is a plurality of radial reinforcement ribs, all of which are evenly arranged along the circumferential direction of the end face of the expansion capsule, each radial reinforcement rib is arranged along the radial direction of the expansion capsule, and the radial reinforcement ribs and the expansion capsule are made into an integral structure.

[0014] The method for operating a reusable hole sealer for gas extraction through-layer drilling in underground coal mines comprises the following steps:

[0015] (1) Carry out gas extraction through-layer drilling construction according to the drilling design requirements and set the sealing pressure P 2 , which is greater than the original gas pressure P of the coal seam 0 ;

[0016] (2) According to the type of surrounding rock of the gas extraction through-layer drilling sealing section, if the surrounding rock is siltstone, fine-grained sandstone or medium-grained sandstone, which is a high-strength rock that is not easily deformed, the sealing device is used to perform the sealing operation;

[0017] (3) After the drilling construction is completed, the hole sealer is placed into the gas extraction borehole screened in step (2), the injection pump is connected to the valve, and the valve switch is turned on;

[0018] (4) Prepare the injection material according to the injection material formula;

[0019] (5) Start the injection pump and first use a pressure less than the pressure of the one-way valve P 1 The injection pressure P 3 Liquid is injected into the hole sealer, and the liquid flows into the second liquid injection inlet pipe, the first liquid injection inlet pipe, the second liquid injection connecting pipe, the middle liquid injection connecting pipe and the first liquid injection connecting pipe in sequence. The liquid is first injected into the second expansion capsule through the second liquid injection hole on the second liquid injection connecting pipe, and then injected into the first expansion capsule through the first liquid injection hole on the first liquid injection connecting pipe. As the pressure in the first expansion capsule and the second expansion capsule continues to increase, the first expansion capsule and the second expansion capsule radially expand and press against the wall of the drilled hole to seal the wall of the drilled hole, and the injection pressure of the injection pump is linearly increased. When the injection pressure reaches the pressure P of the pressure-bearing check valve 1 When the pressure check valve opens, the liquid is injected into the annular cavity between the first expansion capsule and the second expansion capsule. Observe the pressure gauge. When the pressure gauge reading is P 4 Displays that the liquid pressure reaches the sealing pressure P 2 When the liquid injection pump is turned off, the liquid injection is stopped and the valve is closed;

[0020] (6) Repeat step (5) for other selected gas extraction boreholes to complete the sealing;

[0021] (7) Observe the pressure gauge reading P every other day 4 , if the pressure gauge reading P 4 Less than sealing pressure P 2 When the sealing pressure is maintained, connect the injection pump to the valve, open the valve switch, and repeat step (5) to add liquid to the sealing device to maintain the sealing pressure;

[0022] (8) After completing the gas extraction task, open the valve switch. Due to the pressure of the liquid itself, the liquid in the first expansion capsule and the second expansion capsule flows back and flows out through the valve; the first expansion capsule and the second expansion capsule shrink, and the sealing liquid in the borehole between the first expansion capsule and the second expansion capsule flows out as the expansion capsule shrinks, and the sealing pressure disappears; as the expansion capsule shrinks and the sealing pressure disappears, the sealer can be taken out of the borehole.

[0023] The injection material in step (4) is prepared from guar gum, glycerin, borax and water in a certain proportion. The injection material is in a soft gel state, has good fluidity and can withstand a certain pressure.

[0024] Guar gum, glycerin, borax and water are prepared in a weight ratio of 1:3:80:200.

[0025] By adopting the above technical solution, the first liquid injection connecting tube is sealedly connected to the connecting parts of the two end surfaces of the first expansion capsule, and the second liquid injection connecting tube is sealedly connected to the connecting parts of the two end surfaces of the second expansion capsule.

[0026] Gas extraction pipes can be made of steel pipes, PVC pipes, PE pipes, skeleton reinforced plastic pipes or covered spiral corrugated steel pipes according to actual needs.

[0027] The expansion capsule is made of highly elastic and wear-resistant rubber material, and the inner diameter of the cylindrical hole of the expansion capsule is the same as the outer diameter of the gas extraction pipe.

[0028] The present invention mainly has the following technical features and beneficial effects:

[0029] a. Taking advantage of the different characteristics of injection pressures and the design of a pressure-bearing one-way valve, different injection pressures are cleverly used to inject liquid into the hole sealer, so that the injection operation goal can be completed through one injection pipeline.

[0030] b. The expansion capsule is made of highly elastic and wear-resistant rubber. After the expansion capsule expands, several convex sealing strips are pressed against the wall of the drilled hole, which has strong friction and can prevent the hole sealer from slipping.

[0031] c. The pressure gauge connected by the three-way joint can realize real-time monitoring of the sealing pressure. When the sealing pressure is reduced, the sealing device can be replenished with fluid and pressure by connecting the injection pump and opening the valve to maintain the sealing pressure of the sealing device.

[0032] e. After completing the gas extraction task, by opening the valve, the liquid in the expansion capsule will flow back due to the liquid pressure and flow out through the valve; the liquid in the injection area will flow out as the expansion capsule contracts, and the sealing pressure disappears; as the expansion capsule contracts and the sealing pressure disappears, the sealer can be taken out of the borehole, realizing the reuse function of the sealer.

[0033] f. According to the actual requirements on site, the pressure-bearing check valve with different minimum bearing pressure can be replaced to meet the needs of different sealing pressures.

[0034] g. After high-pressure water is filled into the expansion capsule through the injection tube, the expansion capsule expands. Since the inner wall of the borehole is not smooth and flat, but has many depressions or protrusions, the several convex ridge sealing strips on the outer circle of the expanded expansion capsule fit closely according to the depressions or protrusions in different areas of the inner wall of the borehole, thereby ensuring that the sealing section between the first expansion capsule and the second expansion capsule has a better sealing effect. The convex ridge sealing strip also has the function of improving the pressure bearing strength of the expansion capsule. When the inner wall of the borehole moves, the convex ridge sealing strip slides and rubs against the inner wall of the borehole, reducing the wear of the outer circle of the expansion capsule.

[0035] h. The provision of radial reinforcing ribs can improve the pressure-bearing performance of both end surfaces of the expansion capsule (including radial and axial pressure-bearing).

[0036] i. The first liquid injection connecting pipe, the second liquid injection connecting pipe, the middle liquid injection connecting pipe, the first liquid injection inlet pipe and the second liquid injection inlet pipe adopt a split structure. Under the premise of ensuring sealing, quick connection and disassembly can be achieved through quick plug-in connectors, which is easy to operate and improves construction efficiency.

[0037] j. The injection material formula is environmentally friendly, easy to prepare on site, harmless to the rock formation, and can be naturally degraded.

[0038] To sum up, the present invention has a scientific principle, a simple structure, and is easy to operate, and can realize the functions of monitoring the sealing pressure of the gas extraction drilling sealer, re-filling the sealer when the sealing pressure is reduced to increase the sealing pressure, and recycling and reusing the sealer after the gas extraction operation is completed. It can effectively realize the reuse of materials and reduce the sealing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the overall structure of the reusable hole sealer for gas extraction through-layer drilling in underground coal mines in the present invention;

[0040] Figure 2 yes Figure 1 An enlarged schematic diagram of the first expansion capsule;

[0041] Figure 3 yes Figure 2 Top view of the . DETAILED DESCRIPTION

[0042] like Figure 1 , Figure 2 and Figure 3 As shown, the reusable sealing device for gas extraction through-layer drilling in underground coal mines of the present invention comprises a first expansion capsule 2 and a second expansion capsule 3 coaxially mounted on a gas extraction pipe 1, the gas extraction pipe 1 is vertically arranged, the first expansion capsule 2 is located above the second expansion capsule 3, the first expansion capsule 2 and the second expansion capsule 3 are cylindrical in shape and are provided with a cylindrical hole sleeved on the outer circle of the gas extraction pipe 1 along the center line, the present invention also comprises a first liquid injection connecting pipe 4, a second liquid injection connecting pipe 5, an intermediate liquid injection connecting pipe 6, a first liquid injection inlet pipe 7 and a second liquid injection inlet pipe 8, all of which are parallel to the gas extraction pipe 1;

[0043] The first liquid injection connecting tube 4 is inserted into the first expansion capsule 2, the upper end of the first liquid injection connecting tube 4 extends upward from the upper end surface of the first expansion capsule 2 and is provided with a plug 9, the lower end of the first liquid injection connecting tube 4 extends downward from the lower end surface of the first expansion capsule 2, and the first liquid injection connecting tube 4 is provided with a first liquid injection hole 10 communicating with the inner cavity of the first expansion capsule 2;

[0044] The second liquid injection connecting tube 5 is inserted into the second expansion capsule 3, the upper end of the second liquid injection connecting tube 5 extends upward from the upper end surface of the second expansion capsule 3, and the lower end of the second liquid injection connecting tube 5 extends downward from the lower end surface of the second expansion capsule 3. The second liquid injection connecting tube 5 is provided with a second liquid injection hole 11 communicating with the inner cavity of the second expansion capsule 3;

[0045] The upper port of the intermediate injection connecting pipe 6 is connected to the lower port of the first injection connecting pipe 4 through a first quick-plug connector 12, and the lower port of the intermediate injection connecting pipe 6 is connected to the upper port of the second injection connecting pipe 5 through a second quick-plug connector 13. A pressure-bearing one-way valve 14 is provided on the intermediate injection connecting pipe 6;

[0046] The upper port of the first liquid injection inlet pipe 7 is connected to the lower port of the second liquid injection connecting pipe 5 through the third quick-plug connector 15, a three-way connector 16 is provided between the lower port of the first liquid injection inlet pipe 7 and the upper port of the second liquid injection inlet pipe 8, a pressure gauge 17 is provided on the third interface of the three-way connector 16, and a valve 18 is provided at the upper end of the second liquid injection inlet pipe 8.

[0047] The outer circumferences of the first expansion capsule 2 and the second expansion capsule 3 are provided with a convex sealing structure.

[0048] The raised sealing structure includes a plurality of annular convex sealing strips 19, all of which are evenly spaced along the center line of the expansion capsule. The cross section of each convex sealing strip 19 is a semicircular structure, and the convex sealing strip 19 and the expansion capsule are made of an integral structure.

[0049] The first expansion capsule 2 and the second expansion capsule 3 are provided with end surface pressure-bearing reinforcement structures on the upper and lower end planes.

[0050] The end face pressure-bearing reinforcement structure is a plurality of radial reinforcement ribs 20, all of which are evenly arranged along the circumferential direction of the end face of the expansion capsule, each radial reinforcement rib 20 is arranged along the radial direction of the expansion capsule, and the radial reinforcement rib 20 and the expansion capsule are made into an integral structure.

[0051] The first liquid injection connecting tube 4 is sealedly connected to the connecting parts of the two end surfaces of the first expansion capsule 2 , and the second liquid injection connecting tube 5 is sealedly connected to the connecting parts of the two end surfaces of the second expansion capsule 3 .

[0052] The gas extraction pipe 1 can be made of steel pipe, PVC pipe, PE pipe, skeleton reinforced plastic pipe or covered spiral corrugated steel pipe according to actual needs.

[0053] The expansion capsule is made of highly elastic and wear-resistant rubber material, and the inner diameter of the cylindrical hole of the expansion capsule is the same as the outer diameter of the gas extraction pipe 1.

[0054] This sealer is used when the surrounding rock of the gas extraction through-layer drilling sealing section is high-strength and non-deformable rock such as siltstone, fine-grained sandstone, medium-grained sandstone; this sealer is not used when the surrounding rock of the gas extraction through-layer drilling sealing section is low-strength and easily deformable rock such as mudstone, sandy mudstone, etc.

[0055] The injection material is prepared from guar gum, glycerin, borax and water in proportion. The injection material is in a soft gel state, has good fluidity and can withstand a certain pressure.

[0056] The main steps of using the reusable hole sealer for gas extraction through-layer drilling in underground coal mines of the present invention to seal the hole are as follows:

[0057] (1) Carry out gas extraction drilling construction according to the drilling design requirements and set the sealing pressure P 2 , which is greater than the original gas pressure P of the coal seam 0 ;

[0058] (2) According to the type of surrounding rock of the gas extraction through-layer drilling sealing section, if the surrounding rock is siltstone, fine-grained sandstone or medium-grained sandstone, which is high in strength and not easy to deform, use this sealer to seal the hole;

[0059] (3) After the drilling construction is completed, the hole sealer is placed in the gas extraction borehole screened in step (2), the injection pump is connected to the valve 18 (a double-insert ball valve can be used), and the double-insert ball valve switch is turned on;

[0060] (4) Prepare the injection material according to the injection material formula;

[0061] (5) Start the injection pump and first use a pressure P that is less than the pressure of the one-way valve 14 1 The injection pressure P 3 Liquid is injected into the hole sealer, and the liquid flows into the second liquid injection inlet pipe 8, the first liquid injection inlet pipe 7, the second liquid injection connecting pipe 5, the intermediate liquid injection connecting pipe 6 and the first liquid injection connecting pipe 4 in sequence. The liquid is first injected into the second expansion capsule 3 through the second liquid injection hole 11 on the second liquid injection connecting pipe 5, and then injected into the first expansion capsule 2 through the first liquid injection hole 10 on the first liquid injection connecting pipe 4. As the pressure in the first expansion capsule 2 and the second expansion capsule 3 continues to increase, the first expansion capsule 2 and the second expansion capsule 3 radially expand and press against the wall of the drilled hole to seal the wall of the drilled hole, and the injection pressure of the injection pump is linearly increased. When the injection pressure reaches the pressure P of the pressure-bearing one-way valve 14, the pressure of the pressure-bearing one-way valve 14 is increased. 1 When the pressure check valve 14 is opened, the liquid is injected into the annular cavity between the first expansion capsule 2 and the second expansion capsule 3, and the pressure gauge 17 is observed. When the pressure gauge 17 reads P 4 Displays that the liquid pressure reaches the sealing pressure P 2 When the liquid injection pump is turned off, the liquid injection is stopped, and the valve 18 is closed;

[0062] (6) Repeat step (5) for other selected gas extraction boreholes to complete the sealing;

[0063] (7) Observe the pressure gauge 17 reading P every other day 4 , if the pressure gauge 17 reading is P 4 Less than sealing pressure P 2 When the sealing pressure is maintained, the injection pump is connected to the valve 18, the valve 18 is opened, and step (5) is repeated to replenish the liquid in the sealing device to maintain the sealing pressure;

[0064] (8) After completing the gas extraction task, open the valve 18. Due to the pressure of the liquid itself, the liquid in the first expansion capsule 2 and the second expansion capsule 3 flows back and flows out through the valve 18. The first expansion capsule 2 and the second expansion capsule 3 shrink, and the sealing liquid in the borehole between the first expansion capsule 2 and the second expansion capsule 3 flows out as the expansion capsule shrinks, and the sealing pressure disappears. As the expansion capsule shrinks and the sealing pressure disappears, the sealer can be taken out of the borehole. Repeat steps (1), (2), (3), (4), (5), (6), (7), and (8) to achieve the reuse of the sealer.

[0065] The injection material in step (4) is prepared from guar gum, glycerin, borax and water in a certain proportion. The injection material is in a soft gel state, has good fluidity and can withstand a certain pressure.

[0066] Guar gum, glycerin, borax and water are prepared in a weight ratio of 1:3:80:200.

[0067] This embodiment does not impose any formal limitation on the shape, material, structure, etc. of the present invention. Any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. An operating method of a reusable hole sealer for gas extraction through-layer drilling in underground coal mines, characterized in that: The reusable sealing device for gas extraction through-layer drilling in underground coal mines comprises a first expansion capsule and a second expansion capsule coaxially mounted on a gas extraction pipe, the gas extraction pipe is vertically arranged, the first expansion capsule is located above the second expansion capsule, the first expansion capsule and the second expansion capsule are cylindrical in shape and have a cylindrical hole along the center line that is sleeved on the outer circle of the gas extraction pipe, and is characterized in that: it also comprises a first liquid injection connecting pipe, a second liquid injection connecting pipe, an intermediate liquid injection connecting pipe, a first liquid injection inlet pipe and a second liquid injection inlet pipe that are all parallel to the gas extraction pipe; The first liquid injection connecting tube is inserted into the first expansion capsule, the upper end of the first liquid injection connecting tube extends upward from the upper end surface of the first expansion capsule and is provided with a plug, the lower end of the first liquid injection connecting tube extends downward from the lower end surface of the first expansion capsule, and the first liquid injection connecting tube is provided with a first liquid injection hole communicating with the inner cavity of the first expansion capsule; The second liquid injection connecting tube is inserted into the second expansion capsule, the upper end of the second liquid injection connecting tube extends upward from the upper end surface of the second expansion capsule, the lower end of the second liquid injection connecting tube extends downward from the lower end surface of the second expansion capsule, and the second liquid injection connecting tube is provided with a second liquid injection hole communicating with the inner cavity of the second expansion capsule; The upper port of the intermediate liquid injection connecting pipe is connected to the lower port of the first liquid injection connecting pipe through a first quick-plug connector, the lower port of the intermediate liquid injection connecting pipe is connected to the upper port of the second liquid injection connecting pipe through a second quick-plug connector, and a pressure-bearing one-way valve is provided on the intermediate liquid injection connecting pipe; The upper port of the first liquid injection inlet pipe is connected to the lower port of the second liquid injection connecting pipe through a third quick-plug connector, a three-way connector is provided between the lower port of the first liquid injection inlet pipe and the upper port of the second liquid injection inlet pipe, a pressure gauge is provided at the third interface of the three-way connector, and a valve is provided at the upper end of the second liquid injection inlet pipe; The outer circles of the first expansion capsule and the second expansion capsule are provided with a convex sealing structure; The raised sealing structure includes a plurality of annular convex ridge sealing strips, all of which are evenly spaced along the center line of the expansion capsule, and each convex ridge sealing strip has a semicircular cross section, and the convex ridge sealing strip and the expansion capsule are made of an integrated structure; The first expansion capsule and the second expansion capsule are both provided with end surface pressure-bearing reinforcement structures on the upper and lower end planes; The end face pressure-bearing reinforcement structure is a plurality of radial reinforcement convex ribs, all of which are evenly arranged along the circumferential direction of the end face of the expansion capsule, each radial reinforcement convex rib is arranged along the radial direction of the expansion capsule, and the radial reinforcement convex rib and the expansion capsule are made into an integral structure; The operation method comprises the following steps: (1) Carry out gas extraction through-layer drilling construction according to the drilling design requirements, and set the sealing pressure P2, which is greater than the original gas pressure P0 of the coal seam; (2) According to the type of surrounding rock of the gas extraction through-layer drilling sealing section, if the surrounding rock is siltstone, fine-grained sandstone or medium-grained sandstone, which is a high-strength rock that is not easily deformed, the sealing device is used to perform the sealing operation; (3) After the drilling construction is completed, the hole sealer is placed into the gas extraction borehole screened in step (2), the injection pump is connected to the valve, and the valve switch is turned on; (4) Prepare the injection material according to the injection material formula; (5) Start the injection pump. First, use the injection pressure P3 which is less than the pressure P1 of the pressure-bearing check valve to inject liquid into the hole sealer. The liquid flows into the second injection inlet pipe, the first injection inlet pipe, the second injection connecting pipe, the middle injection connecting pipe and the first injection connecting pipe in sequence. The liquid is first injected into the second expansion capsule through the second injection hole on the second injection connecting pipe, and then injected into the first expansion capsule through the first injection hole on the first injection connecting pipe. As the pressure in the first expansion capsule and the second expansion capsule continues to increase, the first expansion capsule and the second expansion capsule radially expand and press against the wall of the borehole to seal the borehole wall. The injection pressure of the injection pump is linearly increased. When the injection pressure reaches the pressure P1 of the pressure-bearing check valve, the pressure-bearing check valve opens, and the liquid is injected into the annular cavity between the first expansion capsule and the second expansion capsule. Observe the pressure gauge. When the pressure gauge reading P4 shows that the liquid pressure reaches the sealing pressure P2, turn off the injection pump, stop the injection, and close the valve. (6) Repeat step (5) for other selected gas extraction boreholes to complete the sealing; (7) Observe the pressure gauge reading P4 every other day. If the pressure gauge reading P4 is less than the sealing pressure P2, connect the injection pump to the valve, open the valve switch, and repeat step (5) to add liquid to the sealing device to maintain the sealing pressure; (8) After completing the gas extraction task, open the valve switch. Due to the pressure of the liquid itself, the liquid in the first expansion capsule and the second expansion capsule flows back and flows out through the valve; the first expansion capsule and the second expansion capsule shrink, and the sealing liquid in the borehole between the first expansion capsule and the second expansion capsule flows out as the expansion capsule shrinks, and the sealing pressure disappears; as the expansion capsule shrinks and the sealing pressure disappears, the sealer can be taken out of the borehole.

2. The method for operating the reusable hole sealer for gas extraction through-layer drilling in underground coal mines according to claim 1, characterized in that: The injection material in step (4) is prepared from guar gum, glycerin, borax and water in a certain proportion. The injection material is in a soft gel state, has good fluidity and can withstand a certain pressure.

3. The method for operating the reusable sealer for gas extraction through-layer drilling in underground coal mines according to claim 2, characterized in that: Guar gum, glycerin, borax and water are prepared in a weight ratio of 1:3:80:200.

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