Sealing device and method for multi-purpose gas drainage and water injection in high-gas coal seams

Abstract

The present invention discloses a hole - sealing device and method for multi - purpose use of gas drainage and water injection in high - gas coal seams. The hole - sealing device comprises a drilling casing closely attached to the inner wall of the water - injection hole, a hole - sealing assembly, and a pulling device formed by a water - injection and gas - extraction pipe, a fixed pulley, and a steel wire rope passing through the hole - sealing assembly. The hole - sealing assembly includes a bottom - hole hole - sealing assembly and an orifice hole - sealing assembly located at the front and rear ends inside the drilling casing. The front end of the drilling casing is in a tapered state, and a hollow - shaped clamping groove frame is provided at the very front end of the drilling casing. The hole - sealing method includes the following steps: drilling a water - injection hole, installing the hole - sealing device in the water - injection hole, performing pressure - bearing grouting through a grouting pipe, connecting the water - injection and gas - extraction pipe to the gas drainage system for gas drainage, after the extraction pressure drops to the set pressure, connecting the water - injection and gas - extraction pipe to the underground water - injection pipeline, and then performing pressure - bearing coal seam water injection. The present invention has the advantages of good stability, good sealing performance, flexible installation, mutual benefit and win - win results, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of coal seam borehole sealing, and particularly relates to a borehole sealing device and method for multi-purpose gas drainage and water injection in high-gas coal seams. Background Art

[0002] In order to eliminate the danger of coal and gas outburst disasters, it is necessary to drain gas from outburst coal seams. In China, a large part of gas extraction is achieved through the extraction of small-diameter boreholes underground. Due to the soft coal body and low permeability in most mining areas in China, the extraction effect is not very satisfactory. As a traditional technical means, the coal seam water injection technology can significantly improve the coal seam permeability and gas extraction rate by injecting high-pressure water into the coal body to promote the development of coal body fractures.

[0003] In the actual production process, whether it is gas extraction or coal seam water injection, boreholes need to be constructed into the coal body. However, since the pressure faced by gas extraction boreholes is relatively low, short-distance grouting sealing can often be used for borehole sealing during operation without the need to withstand high pressure. On the contrary, during coal seam water injection operations, pressures of several megapascals or even dozens of megapascals are often required for water injection to achieve strong permeability enhancement in low-permeability coal seams. Therefore, due to different working conditions, different boreholes need to be constructed for the two technologies to complete the operation. Summary of the Invention

[0004] Aiming at the problems existing in the above-mentioned prior art, the present invention aims to provide a borehole sealing device and method for multi-purpose gas drainage and water injection in high-gas coal seams, which can meet the water injection requirements of high-gas coal seams while facilitating gas extraction, and solve the problem that different boreholes need to be constructed for operation due to different working conditions faced by coal seam water injection and gas extraction.

[0005] To achieve the above object, the present invention provides a hole - sealing device for gas drainage and water injection in high - gas coal seams, which uses one hole for multiple purposes. The device includes a drilling casing closely attached to the inner wall of the water - injection hole, a hole - sealing assembly, and a water - injection and gas - extraction pipe passing through the hole - sealing assembly. The hole - sealing assembly includes a bottom - hole hole - sealing assembly and a hole - mouth hole - sealing assembly located at the front and rear ends inside the drilling casing. The bottom - hole hole - sealing assembly includes a water - absorbing and expanding rubber plug. The front end of the water - absorbing and expanding rubber plug is frustum - shaped, and the rear end is cylindrical. The front end of the drilling casing is in a tapered state, and a hollow - shaped card slot frame is provided at the very front end of the drilling casing. The card slot frame is formed by 4 - 6 metal rods, and its shape is the same as the front - end shape of the water - absorbing and expanding rubber plug. The hole - sealing device further includes a pulling device formed by a fixed pulley and a steel wire rope. The fixed pulley is fixed at the front end of the card slot frame. One end of the steel wire rope is fixed on the water - absorbing and expanding rubber plug, and the other end passes through the water - absorbing and expanding rubber plug after cooperating with the fixed pulley and extends backward. By pulling the steel wire rope, the water - absorbing and expanding rubber plug can be pulled to the front end of the drilling casing, so that the front end of the water - absorbing and expanding rubber plug fits tightly in the card slot frame, and the rear end of the water - absorbing and expanding rubber plug is clamped in the tapered section of the drilling casing. The hole - mouth hole - sealing assembly includes a water - absorbing and expanding rubber cylinder equipped with a grouting pipe and a slurry - return pipe. The slurry outlet of the grouting pipe is close to the water - absorbing and expanding rubber cylinder, and the slurry - return port of the slurry - return pipe is close to the water - absorbing and expanding rubber plug. The water - injection and gas - extraction pipe passes through the central corresponding through - holes of the water - absorbing and expanding rubber cylinder and the water - absorbing and expanding rubber plug and extends deep into the water - injection hole to carry out water injection or gas drainage.

[0006] In the above - mentioned solution: the card slot frame is formed by 4 metal rods, each metal rod is in an "L" shape, and the 4 metal rods are distributed in a "cross" shape, with a simple structure and convenient setting.

[0007] In the above - mentioned solution: when the water - injection hole is a drilling hole that passes through the coal seam at the initial drilling position and reaches other coal seams, the length of the drilling casing is greater than the length of the coal seam at the initial drilling position; when the water - injection hole is a drilling hole drilled along the strike or dip direction of the coal seam, the length of the drilling casing is greater than half of the drilling length, ensuring good coal - seam water - injection effect and meeting the sealing - performance requirements.

[0008] The present invention also provides a hole - sealing method for gas drainage and water injection in high - gas coal seams, which uses one hole for multiple purposes. The method includes the following steps:

[0009] S1. Drilling construction forms a water injection hole, installs the above-mentioned gas drainage and water injection multi-purpose hole sealing device for high-gas coal seams in the water injection hole. First, select and install a suitable drilling casing according to the drilling type of the water injection hole. Connect one end of the steel wire rope to the water-absorbing and expanding rubber plug, and after the other end is matched with the fixed pulley, pass through the water-absorbing and expanding rubber plug. Then, pass the water injection and gas extraction pipe through the water-absorbing and expanding rubber plug and install it at the front end of the card slot frame of the drilling casing. Tighten the steel wire rope to make the front end of the water-absorbing and expanding rubber plug fit tightly with the card slot frame, and make the rear end of the water-absorbing and expanding rubber plug clamped in the tapered section of the drilling casing. Then, pass the water-absorbing and expanding rubber cylinder with the grouting pipe and the return slurry pipe installed through the water injection and gas extraction pipe and install it at the rear end of the drilling casing;

[0010] S2. Carry out pressure grouting through the grouting pipe, and stop grouting when slurry overflows from the return slurry pipe to complete hole sealing;

[0011] S3. Connect the water injection and gas extraction pipe to the gas drainage system and then carry out gas drainage. After the drainage pressure drops to the set pressure, connect the water injection and gas extraction pipe to the underground water injection pipeline, and then carry out pressure water injection into the coal seam. Due to the expansion effect of the water-absorbing and expanding rubber plug and the water-absorbing and expanding rubber cylinder and the fixing effect of the card slot frame, the sealing performance is satisfied, and water injection and pressure maintenance are realized, so as to further displace the coal seam gas and generate a secondary desorption effect, improving the gas drainage pressure.

[0012] In the above scheme: Cement slurry is used for grouting, which is convenient for debugging, has low construction cost and good sealing performance.

[0013] The beneficial effects of the present invention:

[0014] The front end of the drilling casing is in a tapered state, and a hollowed-out card slot frame is provided at the very front end. Through the pulling device, the front end of the water-absorbing and expanding rubber plug can be tightly fitted in the frustum-shaped card slot frame, and the rear end of the water-absorbing and expanding rubber plug is clamped in the tapered section of the drilling casing. The rear end of the water-absorbing and expanding rubber plug is cylindrical, which can effectively ensure the clamping force between the water-expanding rubber plug and the inner wall of the tapered section of the drilling casing; The installation stability of the coal seam drilling hole sealing device is fully guaranteed through two fixed points, and at the same time, the sealing requirements are also met, avoiding the situation that the water-absorbing and expanding rubber plug is pushed to the port of the drilling casing and disengaged due to different pressures inside and outside the drilling casing during grouting, and avoiding the situation that the water-absorbing and expanding rubber plug is pushed back into the drilling casing due to different pressures inside and outside the drilling casing during water injection, resulting in gaps between the inner wall of the drilling casing and the water-absorbing and expanding rubber plug and affecting the sealing effect;

[0015] The pulling device includes a fixed pulley and a steel wire rope. The hollowed-out card slot frame is convenient for installing the fixed pulley and the steel wire rope to pass through. Using the pulling device to fix the water-absorbing and expanding rubber plug, the distance from the water-absorbing and expanding rubber plug to the port of the drilling casing can be judged by pulling out the length of the steel wire rope until it is completely embedded and fixed, greatly simplifying the installation process;

[0016] The orifice plugging assembly includes a water-swellable rubber cylinder equipped with a grouting pipe and a return slurry pipe. The slurry outlet of the grouting pipe is close to the water-swellable rubber cylinder, enabling the slurry to slowly fill from the orifice to the bottom of the hole according to the height difference, effectively reducing the grouting time in combination with the actual application site. The return slurry port of the return slurry pipe is close to the water-swellable rubber plug, which can ensure that the slurry reaches the bottom of the hole according to the overflow situation of the slurry, avoiding the poor plugging effect, poor sealing performance, and poor stability caused by incomplete internal grouting.

[0017] An injection and gas extraction pipe is passed through the plugging assembly to inject water or extract gas inside the water injection hole, meeting the high-pressure tolerance requirements for water injection and the sealing performance requirements for gas extraction at the same time. It can be used for multiple purposes with a wide range of applications. Moreover, 5 After coal seam water injection, due to the expansion effect of the water-swellable rubber and the fixing effect of the card slot frame, water injection pressure can be maintained, thereby further displacing gas, generating a secondary desorption effect, increasing the gas extraction pressure, and enabling the coal seam water injection and gas extraction operations to provide the required environment for each other after implementation, achieving mutual benefit and win-win results.

[0018] In summary, it has the advantages of good stability, good sealing performance, flexible installation, mutual benefit and win-win results, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram before the installation of the present invention.

[0020] Figure 2 is a schematic structural diagram after the installation of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] As Figure 1 and 2 shown, a plugging device for gas extraction and water injection in a high-gas coal seam with multiple uses in one hole mainly

[0022] consists of a drilling casing 1 closely attached to the inner wall of the water injection hole 5, a plugging assembly, an injection and gas extraction pipe 4 passing through the plugging assembly, and a pulling device formed by a combination of a fixed pulley 16 and a steel wire rope 15. 5 The plugging assembly includes a bottom hole plugging assembly 2 and an orifice plugging assembly 3 located at the front and rear ends inside the drilling casing 1.

[0023] The bottom hole plugging assembly 2 includes a water-swellable rubber plug 12, with the front end of the water-swellable rubber plug 12 being frustum-shaped and the rear end being cylindrical. The front end of the drilling casing 1 is in a tapered state, and a hollowed-out

[0024] card slot frame 17 is provided at the very front end of the drilling casing 1. The card slot frame 17 is formed by enclosing 4 to 6 metal rods, and its shape is the same as the shape of the front end of the water-swellable rubber plug 12.

[0025] The shape is consistent. 0 The shape is the same.

[0026] The fixed pulley 16 is fixed at the front end of the card slot frame 17. One end of the steel wire rope 15 is fixed on the water-absorbing and expanding rubber plug 12, and the other end passes through the water-absorbing and expanding rubber plug 12 after being engaged with the fixed pulley 16. By pulling the steel wire rope 15, the water-absorbing and expanding rubber plug 12 can be pulled to the front end of the drilling casing 1, so that the front end of the water-absorbing and expanding rubber plug 12 fits tightly in the card slot frame 17, and the rear end of the water-absorbing and expanding rubber plug 12 is clamped in the tapered section of the drilling casing 1.

[0027] The orifice sealing assembly 3 includes a water-absorbing and expanding rubber cylinder 11 equipped with a grouting pipe 13 and a slurry return pipe 14. The slurry outlet of the grouting pipe 13 is close to the water-absorbing and expanding rubber cylinder 11, and the slurry return port of the slurry return pipe 14 is close to the water-absorbing and expanding rubber plug 12.

[0028] The water injection and gas extraction pipe 4 passes through the central through holes of the water-absorbing and expanding rubber cylinder 11 and the water-absorbing and expanding rubber plug 12 and then extends into the water injection hole to carry out water injection or gas extraction.

[0029] Preferably, the card slot frame 17 is surrounded by 4 metal rods. Each metal rod is in an "L" shape, and the 4 metal rods are distributed in a "cross" shape, with a simple structure and convenient installation.

[0030] Preferably, when the water injection hole 5 is a borehole that penetrates the coal seam at the initial drilling position and reaches other coal seams, the length of the drilling casing 1 is greater than the length of the coal seam at the initial drilling position. When the water injection hole 5 is a borehole drilled along the strike or dip direction of the coal seam, the length of the drilling casing 1 is greater than half of the borehole length, ensuring good coal seam water injection effect and meeting the sealing performance requirements.

[0031] A method for sealing holes for gas extraction and water injection in a high-gas coal seam with multiple uses in one hole is as follows:

[0032] Drill a water injection hole 5, install the above-mentioned hole sealing device for gas extraction and water injection in a high-gas coal seam with multiple uses in one hole in the water injection hole 5. First, select and install a suitable drilling casing 1 according to the type of the water injection hole 5. Connect one end of the steel wire rope 15 to the water-absorbing and expanding rubber plug 12, and the other end passes through the water-absorbing and expanding rubber plug 12 after being engaged with the fixed pulley 16; then pass the water injection and gas extraction pipe 4 through the water-absorbing and expanding rubber plug 12 and install it at the front end of the card slot frame 17 of the drilling casing 1. Tighten the steel wire rope 15 so that the front end of the water-absorbing and expanding rubber plug 12 fits tightly with the card slot frame 17, and the rear end of the water-absorbing and expanding rubber plug 12 is clamped in the tapered section of the drilling casing 1; then pass the water-absorbing and expanding rubber cylinder 11 equipped with the grouting pipe 13 and the slurry return pipe 14 through the water injection and gas extraction pipe 4 and install it at the rear end of the drilling casing 1.

[0033] Carry out pressure grouting through the grouting pipe 13, and stop grouting when slurry overflows from the slurry return pipe 14 to complete hole sealing.

[0034] After connecting the water injection and gas extraction pipe 4 to the gas drainage system for gas drainage, when the extraction pressure drops to the set pressure, the water injection and gas extraction pipe 4 is connected to the underground water injection pipeline, and then pressure-bearing coal seam water injection is carried out. Due to the expansion effect of the water-absorbing and expanding rubber plug 12 and the water-absorbing and expanding rubber cylinder 11 and the fixing effect of the card slot frame 17, the sealing performance is satisfied, and water injection and pressure maintenance are realized, thereby further displacing the coal seam gas and generating a secondary desorption effect to increase the gas drainage pressure.

[0035] Preferably, the grouting uses cement slurry, which is convenient for debugging, has a low construction cost, and good sealing performance.

[0036] Circularly connecting the gas drainage pipeline and the coal seam water injection pipeline can achieve the effect of multi-purpose use of a single hole for coal seam drilling, gas drainage, and coal seam water injection.

Claims

1. A hole - sealing device for multi - purpose gas drainage and water injection in high - gas coal seams, comprising a drilling casing (1) closely attached to the inner wall of the water - injection hole (5), a hole - sealing assembly, and a water - injection and gas - extraction pipe (4) passing through the hole - sealing assembly. The hole - sealing assembly includes a bottom - hole hole - sealing assembly (2) and an orifice hole - sealing assembly (3) located at the front and rear ends inside the drilling casing (1). It is characterized in that: The bottom - hole hole - sealing assembly (2) includes a water - absorbing and swelling rubber plug (12). The front end of the water - absorbing and swelling rubber plug (12) is frustum - shaped, and the rear end is cylindrical. The front end of the drilling casing (1) is in a tapered state. At the very front end of the drilling casing (1), there is a hollow - shaped card slot frame (17). The card slot frame (17) is formed by 4 - 6 metal rods, and its shape is the same as the front - end shape of the water - absorbing and swelling rubber plug (12). The hole - sealing device also includes a pulling device formed by a fixed pulley (16) and a steel wire rope (15). The fixed pulley (16) is fixed at the front end of the card slot frame (17). One end of the steel wire rope (15) is fixed on the water - absorbing and swelling rubber plug (12), and the other end passes through the water - absorbing and swelling rubber plug (12) after cooperating with the fixed pulley (16) and extends backward. By pulling the steel wire rope (15), the water - absorbing and swelling rubber plug (12) can be pulled to the front end of the drilling casing (1), so that the front end of the water - absorbing and swelling rubber plug (12) fits tightly in the card slot frame (17), and the rear end of the water - absorbing and swelling rubber plug (12) is clamped in the tapered section of the drilling casing (1). The orifice hole - sealing assembly (3) includes a water - absorbing and swelling rubber cylinder (11) equipped with a grouting pipe (13) and a slurry - return pipe (14). The slurry outlet of the grouting pipe (13) is close to the water - absorbing and swelling rubber cylinder (11), and the slurry - return port of the slurry - return pipe (14) is close to the water - absorbing and swelling rubber plug (12). The water - injection and gas - extraction pipe (4) passes through the central through - holes of the water - absorbing and swelling rubber cylinder (11) and the water - absorbing and swelling rubber plug (12) and extends deep into the water - injection hole to carry out water injection or gas drainage.

2. The hole - sealing device for multi - purpose gas drainage and water injection in high - gas coal seams according to claim 1, It is characterized in that: The card slot frame (17) is formed by 4 metal rods. Each metal rod is in an "L" shape, and the 4 metal rods are distributed in a "cross" shape.

3. The hole - sealing device for multi - purpose gas drainage and water injection in high - gas coal seams according to claim 1, It is characterized in that: When the water - injection hole (5) is a drilling hole that penetrates the coal seam at the initial drilling position and reaches other coal seams, the length of the drilling casing (1) is greater than the length of the coal seam at the initial drilling position; when the water - injection hole (5) is a drilling hole drilled along the strike or dip direction of the coal seam, the length of the drilling casing (1) is greater than half of the drilling length.

4. A hole - sealing method for multi - purpose gas drainage and water injection in high - gas coal seams, It is characterized in that, It includes the following steps: S1. Drill a hole to form a water injection hole (5), install the gas drainage and water injection multi-purpose hole sealing device for high-gas coal seams described in any one of claims 1-3 in the water injection hole (5). First, select and install a suitable drilling casing (1) according to the type of the water injection hole (5). Connect one end of the steel wire rope (15) to the water-absorbing and expanding rubber plug (12), and after the other end is fitted with a fixed pulley (16), pass it through the water-absorbing and expanding rubber plug (12). Then, pass the water injection and gas extraction pipe (4) through the water-absorbing and expanding rubber plug (12) and install it at the front end of the clamping groove frame (17) of the drilling casing (1). Tighten the steel wire rope (15) so that the front end of the water-absorbing and expanding rubber plug (12) fits tightly with the clamping groove frame (17), and the rear end of the water-absorbing and expanding rubber plug (12) is clamped in the tapered section of the drilling casing (1). Then, pass the water-absorbing and expanding rubber cylinder (11) equipped with a grouting pipe (13) and a slurry return pipe (14) through the water injection and gas extraction pipe (4) and install it at the rear end of the drilling casing (1); S2. Conduct pressure grouting through the grouting pipe (13), and stop grouting when slurry overflows from the slurry return pipe (14) to complete hole sealing; S3. Connect the water injection and gas extraction pipe (4) to the gas drainage system to conduct gas drainage. After the drainage pressure drops to the set pressure, connect the water injection and gas extraction pipe (4) to the underground water injection pipeline, and then conduct pressure water injection into the coal seam. Due to the expansion effect of the water-absorbing and expanding rubber plug (12) and the water-absorbing and expanding rubber cylinder (11) and the fixing effect of the clamping groove frame (17), the sealing performance is satisfied, and water injection and pressure maintenance are achieved, thereby further displacing the coal seam gas and generating a secondary desorption effect to increase the gas drainage pressure.

5. The hole sealing method for gas drainage and water injection in high-gas coal seams using a single hole for multiple purposes according to claim 4, characterized in that: Cement slurry is used for grouting.

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