Coal body fissure channel water and methane flow visualization system and method

Abstract

The invention discloses a coal body fissure channel water and methane flow visualization system and a coal body fissure channel water and methane flow visualization method. Comprising a methane gas cylinder, a fluorescent powder injection device, a fluorescent aerosol preparation device, a fluorescent aerosol pressurizing injection device, a hydraulic injection device, a water tank, a visual coal sample coating device, a nuclear magnetism testing device, a computer data acquisition device, an oil pump, a back pressure valve and a vacuum pump, the visual coal sample coating device comprises a visual top cover, a visual base, a visual pressure head, a fluorescence imaging camera, a rotary gasket, a rotary valve and a coal sample; according to the device, the defects in the prior art are overcome, fluorescent powder and methane gas can be mixed to form fluorescent aerosol, and after the fluorescent aerosol is injected into coal sample cracks, flowing and distribution visualization of the methane gas is achieved through the fluorescent imaging camera; the flowing process of water in the coal sample fracture channel is observed in combination with a nuclear magnetic testing device, so that the two-phase flow dynamic migration process of the water and the methane gas in the coal sample fracture channel is visualized.

Description

Technical Field

[0001] The present invention relates to the technical field of coal body gas-liquid two-phase flow migration, and in particular to a system and method for visualizing water and methane flow in coal body fracture channels. Background Art

[0002] During coal mining, methane in coal seams is considered a potential safety hazard, with accidents such as gas outbursts, gas outbursts, and gas explosions occurring frequently. Furthermore, methane is a more potent greenhouse gas than carbon dioxide. If not properly utilized and released directly into the atmosphere, it can have adverse environmental impacts. Methane in coal seams can also serve as an unconventional natural gas energy source, known as coalbed methane (CBM), which has enormous development potential. Studying the migration of methane in coal is crucial for ensuring safe coal mine production, reducing greenhouse gas emissions, and enhancing the comprehensive utilization of unconventional resources. Methane in coal seams seeps out of the coal body through fracture channels. Studying the seepage patterns of methane in coal can more accurately predict and control its flow behavior, allowing for the timely identification of areas of abnormal gas accumulation and release, enabling the implementation of appropriate protective measures, such as coal seam water injection and hydraulic fracturing, to increase gas extraction efficiency and reduce the risk of gas accidents.

[0003] At present, predecessors have conducted a lot of theoretical, experimental and simulation research on the characteristics, laws and mechanisms of methane migration in coal bodies, established a large number of empirical formulas and theoretical models and continuously improved them. The purpose is to establish a mathematical model for more accurately describing the actual release process of methane gas in coal. A series of experimental systems have also been developed and a large number of numerical simulation studies have been carried out through modeling to explore the true migration laws of methane in coal to the greatest extent.

[0004] However, the following problems exist: most methane migration test systems have relatively simple testing functions and are unable to visualize the methane gas migration process and the true laws of gas-liquid two-phase flow migration in the presence of water. They cannot form a complete test system, and are limited by experimental conditions and observation methods. It is difficult to systematically, comprehensively, intuitively and quantitatively visualize the dynamic process of gas-liquid two-phase flow migration in coal bodies, especially for the simultaneous observation of water and methane migration processes. There is still a lack of an effective visualization test system and method.

[0005] Therefore, it is necessary to provide a system and method for visualizing water and methane flow in coal body fracture channels to solve the above technical problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a system and method for visualizing water and methane flow in coal body fissure channels, so as to solve the problems existing in the prior art.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A system for visualizing water and methane flow in coal fracture channels comprises: a methane gas cylinder 1, a fluorescent powder injection device 2, a fluorescent aerosol preparation device 3, a fluorescent aerosol pressurized injection device 4, a hydraulic injection device 11, a water tank 12, a visual coal sample coating device 6, a nuclear magnetic resonance testing device 5, a computer data acquisition device 9, an oil pump 10, a back pressure valve 7, and a vacuum pump 8. The visual coal sample coating device 6 comprises a visual top cover 61, a visual base 62, a visual pressure head 63, a fluorescent imaging camera 64, a rotary washer 65, a rotary valve 651, and a coal sample 66; the visual pressure head 63 is located at the bottom of the visual top cover 61, and the oil pump 10 is connected to the visual top cover 61 through a pipeline. The visualization top cover 61 is raised and lowered to apply covering pressure to the coal sample 66; the fluorescent imaging camera 64 is embedded in the visualization top cover 61 and is located above the visualization pressure head 63; the computer data acquisition device 9 is connected to the fluorescent imaging camera 64; the computer data acquisition device 9 is connected to the nuclear magnetic testing device 5; the rotating gasket 65 is located on the inner side of the visualization base 62 and contacts the side of the visualization pressure head 63, and the rotary valve 651 is connected to the rotating gasket 65. The rotating valve 651 can be used to control the rotating gasket 65 to move toward the side of the visualization pressure head 63 to ensure the airtightness of the coal sample 66; the outlet 682 of the visualization coal sample covering device 6 is connected to the vacuum pump 8 and the back pressure valve 7 respectively through a three-way valve.

[0009] Furthermore, the methane gas cylinder 1 is connected to the fluorescent aerosol preparation device 3 through a pipeline, and is used to inject methane gas into the fluorescent aerosol preparation device 3; the fluorescent powder injection device 2 is connected to the fluorescent aerosol preparation device 3 through a pipeline, and is used to inject fluorescent powder into the fluorescent aerosol preparation device 3.

[0010] Furthermore, the fluorescent aerosol preparation device 3 is used to fully mix the methane gas and the fluorescent powder to form a fluorescent aerosol with the methane gas as the dispersion medium and the fluorescent powder as the dispersoid.

[0011] Furthermore, the fluorescent aerosol pressurized injection device 4 is connected to the fluorescent aerosol preparation device 3 through a pipeline, and is used to pressurize the aerosol prepared in the fluorescent aerosol preparation device 3 to ensure that it is injected into the visual coal sample coating device 6 at a constant pressure; the fluorescent aerosol pressurized injection device 4 is connected to the air source inlet 681 of the visual coal sample coating device 6 through a pipeline, and is used to inject fluorescent aerosol into the first fissure channel 68 and the second fissure channel 69 of the coal sample.

[0012] Furthermore, one end of the hydraulic injection device 11 is connected to the water tank 12 via a pipeline, and the other end is connected to the water source inlet 671 of the visual coal sample covering device 6 via a pipeline, for injecting water into the coal sample borehole 67 for fracturing.

[0013] Furthermore, the visual coal sample covering device 6 is made of non-magnetic transparent glass material, which can avoid interference with the monitoring of water nuclear magnetic signals in the coal sample fracture channel.

[0014] Furthermore, the density of the fluorescent powder is close to that of methane gas, and it can be evenly suspended in the methane gas medium without settling due to gravity. The particle size of the fluorescent powder ranges from 30 to 100 nm. The fluorescent powder is insoluble in water. The fluorescent powder injection device 2 can control the mass of the injected fluorescent powder, thereby controlling the concentration of the fluorescent aerosol.

[0015] A method for visualizing water and methane flow in coal fracture channels, characterized by comprising the following steps:

[0016] 1) Select raw coal and use a sand wire cutter and sandpaper to cut and grind it into a coal sample that matches the size of the visual coal sample covering device 6;

[0017] 2) etching a first fracture channel 68, a second fracture channel 69 and a drill hole 67 on the upper surface of the coal sample;

[0018] 3) Place the coal sample in the visualization coal sample covering device 6, set the covering pressure to 5 MPa, and after evacuation, introduce fluorescent aerosol at a pressure of 2 MPa into the gas source inlet 681 through the fluorescent aerosol booster injection device 4. Control the outlet pressure to 1 MPa through the back pressure valve 7. Turn on the fluorescent imaging camera to capture the flow images of methane gas in the first fracture channel 68 and the second fracture channel 69 at different times. Close the gas source inlet 681 until the methane flow images stabilize.

[0019] 4) Turn on the hydraulic injection device 11 and inject 10 MPa water into the borehole 67 through the water source inlet 671 for hydraulic fracturing. Use the nuclear magnetic resonance testing device 5 to capture the flow image of water in the borehole and the fracturing cracks during the hydraulic fracturing process. When the fluorescence imaging camera 64 observes that the flow image of methane gas in the first fracture channel 68 and the second fracture channel 69 changes, and when the nuclear magnetic resonance testing device 5 captures the flow image of water in the first fracture channel 68 and the second fracture channel 69, it indicates that the hydraulic fracturing crack is connected to the first fracture channel 68 and the second fracture channel 69. Continue to observe the flow images of methane gas and water in the first fracture channel 68, the second fracture channel 69 and the borehole 67 under the fluorescence imaging camera 64 and the nuclear magnetic resonance testing device 5, thereby achieving visual observation of the methane-water gas-liquid two-phase flow in the coal sample;

[0020] Furthermore, the coal sample size in step 1 is 50mm*30mm*10mm; in step 2, the radius of the first fracture channel is 100 microns, the radius of the second fracture channel is 500 microns, and the radius of the drill hole is 3mm; the first fracture channel, the second fracture channel and the drill hole are etched using laser etching technology; the first fracture channel, the second fracture channel and the drill hole cross-section are all semicircular; the place where the water source inlet 671 is connected to the drill hole 67 is covered with a sealing sleeve 672.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention provides a system and method for visualizing the flow of water and methane in coal body fissure channels, which can fully and evenly mix fluorescent powder and methane gas to form a fluorescent aerosol. After the fluorescent aerosol is injected into the coal sample fissure, the fluorescent aerosol can be stimulated to produce fluorescence under the irradiation of the excitation light source of the fluorescent imaging camera. The dynamic migration process of methane gas in the coal sample fissure can be captured in real time by the fluorescent imaging camera, thereby realizing the visualization of the flow and distribution of methane gas. During the water injection and fracturing of the coal sample, the nuclear magnetic resonance testing device is used to capture and record the migration image of water in real time, observe the flow process of water in the coal sample borehole and fissure channel during the hydraulic fracturing of the borehole, and visualize the coal sample crack expansion law during the hydraulic fracturing process. In addition, the fluorescent imaging camera is used to simultaneously observe the two-phase flow process of water and methane gas in the coal sample fissure channel, so that the dynamic flow process of water and methane gas in the coal sample fissure channel under the condition of overburden load can be visualized. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 It is a structural schematic diagram of the visual coal sample coating device of the present invention;

[0025] Figure 3 It is a top view schematic diagram of the coal sample of the present invention.

[0026] Among them, 1-methane gas cylinder; 2-fluorescent powder injection device; 3-fluorescent aerosol preparation device; 4-fluorescent aerosol pressurized injection device; 5-nuclear magnetic resonance testing device; 6-visualized coal sample coating device; 7-back pressure valve; 8-vacuum pump; 9-computer data acquisition device; 10-oil pump; 11-hydraulic injection device; 12-water tank; 61-visualized top cover; 62-visualized base; 63-visualized pressure head; 64-fluorescent imaging camera; 65-rotating gasket; 66-coal sample; 67-drill hole; 68-first fracture channel; 69-second fracture channel; 651-rotating valve; 671-water source inlet; 672-sealing sleeve; 681-gas source inlet; 682-outlet. DETAILED DESCRIPTION

[0027] The following embodiments of the technical solution of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention.

[0028] like Figure 1-3 As shown, a system for visualizing water and methane flow in coal fracture channels comprises: a methane gas cylinder 1, a fluorescent powder injection device 2, a fluorescent aerosol preparation device 3, a fluorescent aerosol pressurized injection device 4, a hydraulic injection device 11, a water tank 12, a visual coal sample covering device 6, a nuclear magnetic testing device 5, a computer data acquisition device 9, an oil pump 10, a back pressure valve 7 and a vacuum pump 8. The visual coal sample covering device 6 comprises a visual top cover 61, a visual base 62, a visual pressure head 63, a fluorescent imaging camera 64, a rotary gasket 65, a rotary valve 651 and a coal sample 66; the visual pressure head 63 is located at the bottom of the visual top cover 61, and the oil pump 10 is connected to the visual top cover 61 through a pipeline, and applies covering pressure to the coal sample 66 by controlling the lifting of the visual top cover 61 and thus controlling the lifting of the visual pressure head 63; the fluorescent imaging camera 64 is embedded in the visual top cover 61, located above the visual pressure head 63, and the fluorescent imaging The camera 64 can observe the flow behavior of the fluorescent aerosol in the coal sample under the action of the covering pressure through the visualization pressure head 63; the computer data acquisition device 9 is connected to the fluorescent imaging camera 64, and the fluorescent signal captured by the fluorescent imaging camera is displayed in real time for imaging, thereby visualizing the methane migration process; the computer data acquisition device 9 is connected to the nuclear magnetic testing device 5, and is used to display the data captured by the nuclear magnetic testing device 5 in real time for imaging, thereby visualizing the water migration process; the rotating gasket 65 is located on the inner side of the visualization base 62 and contacts the side of the visualization pressure head 63, and the rotary valve 651 is connected to the rotating gasket 65. The rotating valve 651 can be used to control the rotating gasket 65 to move toward the side of the visualization pressure head 63 to ensure the airtightness of the coal sample 66; the outlet 682 of the visualization coal sample covering device 6 is connected to the vacuum pump 8 and the back pressure valve 7 through a three-way valve, respectively, for evacuating the visualization coal sample covering device 6 and controlling the outlet pressure.

[0029] Furthermore, the methane gas cylinder 1 is connected to the fluorescent aerosol preparation device 3 through a pipeline, and is used to inject methane gas into the fluorescent aerosol preparation device 3; the fluorescent powder injection device 2 is connected to the fluorescent aerosol preparation device 3 through a pipeline, and is used to inject fluorescent powder into the fluorescent aerosol preparation device 3.

[0030] Furthermore, the fluorescent aerosol preparation device 3 is used to fully mix the methane gas and the fluorescent powder to form a fluorescent aerosol with the methane gas as the dispersion medium and the fluorescent powder as the dispersoid.

[0031] Furthermore, the fluorescent aerosol pressurized injection device 4 is connected to the fluorescent aerosol preparation device 3 through a pipeline, and is used to pressurize the aerosol prepared in the fluorescent aerosol preparation device 3 to ensure that it is injected into the visual coal sample coating device 6 at a constant pressure; the fluorescent aerosol pressurized injection device 4 is connected to the air source inlet 681 of the visual coal sample coating device 6 through a pipeline, and is used to inject fluorescent aerosol into the first fissure channel 68 and the second fissure channel 69 of the coal sample.

[0032] Furthermore, one end of the hydraulic injection device 11 is connected to the water tank 12 through a pipeline, and the water tank provides water for the continuous hydraulic fracturing process. The other end is connected to the water source inlet 671 of the visual coal sample coating device 6 through a pipeline, which is used to inject water into the coal sample borehole 67 for fracturing.

[0033] Furthermore, the visual coal sample covering device 6 is made of non-magnetic transparent glass material, which can avoid interference with the monitoring of water nuclear magnetic signals in the coal sample fracture channel.

[0034] Furthermore, the density of the fluorescent powder is close to that of methane gas, and it can be evenly suspended in the methane gas medium without settling due to gravity. The particle size of the fluorescent powder ranges from 30 to 100 nm, and the fluorescent powder is insoluble in water. The fluorescent powder injection device 2 can control the mass of the injected fluorescent powder, and thereby control the concentration of the fluorescent aerosol prepared in the fluorescent aerosol preparation device 3.

[0035] A method for visualizing water and methane flow in coal fracture channels, characterized by comprising the following steps:

[0036] 1) Select raw coal and use a sand wire cutter and sandpaper to cut and grind it into a coal sample that matches the size of the visual coal sample covering device 6;

[0037] 2) etching a first fracture channel 68, a second fracture channel 69 and a drill hole 67 on the upper surface of the coal sample;

[0038] 3) The coal sample is placed in the visualization coal sample covering device 6, and the covering pressure is set to 5 MPa. After vacuuming, a fluorescent aerosol with a pressure of 2 MPa is introduced into the gas source inlet 681 through the fluorescent aerosol booster injection device 4, and the outlet pressure is controlled to 1 MPa by the back pressure valve 7. The fluorescent imaging camera is turned on to capture the flow images of methane gas in the first fracture channel 68 and the second fracture channel 69 at different times. The gas source inlet 681 is closed until the methane flow image is stable. The principle of fluorescence imaging is: since methane gas itself does not have significant fluorescence properties, fluorescent powder with fluorescent properties is added to the methane gas. These fluorescent powders can mix with methane gas to form fluorescent aerosols, which emit fluorescence after absorbing laser light of a specific wavelength. By monitoring the intensity and distribution of these fluorescent signals, the flow and distribution of methane gas can be visualized.

[0039] 4) Turn on the hydraulic injection device 11 and inject 10 MPa water into the borehole 67 through the water source inlet 671 for hydraulic fracturing. Use the nuclear magnetic resonance testing device 5 to capture the flow image of water in the borehole and the fracturing cracks during the hydraulic fracturing process. When the fluorescence imaging camera 64 observes that the flow image of methane gas in the first fracture channel 68 and the second fracture channel 69 changes, and when the nuclear magnetic resonance testing device 5 captures the flow image of water in the first fracture channel 68 and the second fracture channel 69, it indicates that the hydraulic fracturing crack is connected to the first fracture channel 68 and the second fracture channel 69. Continue to observe the flow images of methane gas and water in the first fracture channel 68, the second fracture channel 69 and the borehole 67 under the fluorescence imaging camera 64 and the nuclear magnetic resonance testing device 5, thereby achieving visual observation of the methane-water gas-liquid two-phase flow in the coal sample;

[0040] Furthermore, the coal sample size in step 1 is 50mm*30mm*10mm; in step 2, the radius of the first fracture channel is 100 microns, the radius of the second fracture channel is 500 microns, and the radius of the drill hole is 3mm; the first fracture channel, the second fracture channel and the drill hole are etched using laser etching technology; the first fracture channel, the second fracture channel and the drill hole cross-section are all semicircular; the place where the water source inlet 671 is connected to the drill hole 67 is covered with a sealing sleeve 672.

[0041] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A system for visualizing water and methane flow in coal fracture channels, comprising: A methane gas cylinder (1), a fluorescent powder injection device (2), a fluorescent aerosol preparation device (3), a fluorescent aerosol pressurized injection device (4), a hydraulic injection device (11), a water tank (12), a visual coal sample coating device (6), a nuclear magnetic testing device (5), a computer data acquisition device (9), an oil pump (10), a back pressure valve (7) and a vacuum pump (8); the visual coal sample coating device (6) comprises a visual top cover (61), a visual base (62), a visual pressure head (63), a fluorescent imaging camera (64), a rotary washer (65), a rotary valve (651) and a coal sample (66); the visual pressure head (63) is located at the bottom of the visual top cover (61); the oil pump (10) is connected to the visual top cover (61) through a pipeline, and the visual top cover (61) is controlled by rotating the oil pump (10). The device is lifted and lowered to apply covering pressure to the coal sample (66); the fluorescent imaging camera (64) is embedded in the visualization top cover (61) and is located above the visualization pressure head (63); the computer data acquisition device (9) is connected to the fluorescent imaging camera (64); the computer data acquisition device (9) is connected to the nuclear magnetic testing device (5); the rotating gasket (65) is located on the inner side of the visualization base (62) and contacts the side of the visualization pressure head (63); the rotating valve (651) is connected to the rotating gasket (65), and the rotating gasket (65) can be controlled by the rotating valve (651) to move toward the side of the visualization pressure head (63) to ensure the airtightness of the coal sample (66); the outlet (682) of the visualization coal sample covering device (6) is connected to the vacuum pump (8) and the back pressure valve (7) respectively through the three-way valve.

2. A coal body fracture channel water and methane flow visualization system according to claim 1, characterized in that: The methane gas cylinder 1 is connected to the fluorescent aerosol preparation device (3) through a pipeline and is used to inject methane gas into the fluorescent aerosol preparation device (3); the fluorescent powder injection device (2) is connected to the fluorescent aerosol preparation device (3) through a pipeline and is used to inject fluorescent powder into the fluorescent aerosol preparation device (3).

3. A coal body fracture channel water and methane flow visualization system according to claim 1, characterized in that: The fluorescent aerosol preparation device (3) is used for fully mixing methane gas and fluorescent powder to form fluorescent aerosol with methane gas as dispersion medium and fluorescent powder as dispersion medium.

4. A coal body fracture channel water and methane flow visualization system according to claim 1, characterized in that: The fluorescent aerosol pressurized injection device (4) is connected to the fluorescent aerosol preparation device (3) via a pipeline, and is used to pressurize the fluorescent aerosol prepared in the fluorescent aerosol preparation device (3) to ensure that it is injected into the visual coal sample covering device (6) at a constant pressure; the fluorescent aerosol pressurized injection device (4) is connected to the gas source inlet (681) of the visual coal sample covering device (6) via a pipeline, and is used to inject the fluorescent aerosol into the first fissure channel (68) and the second fissure channel (69) of the coal sample.

5. The system for visualizing water and methane flow in coal fracture channels according to claim 1, characterized in that: One end of the hydraulic injection device (11) is connected to the water tank (12) via a pipeline, and the other end is connected to the water source inlet (671) of the visual coal sample covering device (6) via a pipeline, and is used for injecting water into the coal sample borehole (67) for fracturing.

6. A coal body fracture channel water and methane flow visualization system according to claim 1, characterized in that: The visual coal sample covering device (6) is made of non-magnetic transparent glass material, which can avoid interference with the monitoring of water nuclear magnetic signals in the coal sample fracture channel.

7. A coal body fracture channel water and methane flow visualization system according to claim 2, characterized in that: The density of the fluorescent powder is close to that of methane gas, and the fluorescent powder can be evenly suspended in the methane gas medium without settling due to gravity. The particle size of the fluorescent powder is in the range of 30-100 nm. The fluorescent powder is insoluble in water. The fluorescent powder injection device (2) can control the mass of the injected fluorescent powder, thereby controlling the concentration of the fluorescent aerosol.

8. A method for visualizing water and methane flow in coal fracture channels, characterized by: The steps include: 1) Select raw coal and use a sand wire cutter and sandpaper to cut and grind it into a coal sample that matches the size of the visual coal sample covering device (6); 2) etching a first fracture channel (68), a second fracture channel (69) and a drill hole (67) on the upper surface of the coal sample; 3) placing the coal sample into a visual coal sample covering device (6), setting the covering pressure to 5 MPa, and after evacuation, introducing fluorescent aerosol with a pressure of 2 MPa into the gas source inlet (681) through the fluorescent aerosol booster injection device (4), controlling the outlet pressure to 1 MPa through the back pressure valve (7), turning on the fluorescent imaging camera to capture the flow images of methane gas in the first fissure channel (68) and the second fissure channel (69) at different times, and closing the gas source inlet (681) after the methane flow images are stable; 4) Turn on the hydraulic injection device (11), inject 10MPa water into the borehole (67) through the water source inlet (671) to perform hydraulic fracturing, and use the nuclear magnetic resonance testing device (5) to capture the flow image of water in the borehole and the fracturing crack during the hydraulic fracturing process. When the fluorescence imaging camera (64) observes that the flow image of methane gas in the first fracture channel (68) and the second fracture channel (69) changes, and when the nuclear magnetic resonance testing device (5) captures the flow image of water in the first fracture channel (68) and the second fracture channel (69), it indicates that the hydraulic fracturing crack is connected with the first fracture channel (68) and the second fracture channel (69). Continue to observe the flow images of methane gas and water in the first fracture channel (68), the second fracture channel (69) and the borehole (67) under the fluorescence imaging camera (64) and the nuclear magnetic resonance testing device (5), thereby realizing the visualization observation of the methane-water gas-liquid two-phase flow in the coal sample.

9. A method for visualizing water and methane flow in coal fracture channels according to claim 8, characterized in that: The coal sample size in step 1 is 50mm*30mm*10mm; in step 2, the radius of the first fracture channel is 100 microns, the radius of the second fracture channel is 500 microns, and the radius of the drill hole is 3mm; the first fracture channel, the second fracture channel and the drill hole are etched using laser etching technology; the cross-sections of the first fracture channel, the second fracture channel and the drill hole are all semicircular; the place where the water source inlet (671) is connected to the drill hole (67) is covered with a sealing sleeve (672).

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