A system and method for enhancing coal seam injectability by using gas-water miscible medium

Abstract

A system and method for enhancing the injectability of coal seams with gas-water miscible medium, system: a liquid water storage tank, a water pump and an intelligent heater are connected in sequence and then divided into two paths through a three-way valve, one path is connected to the liquid inlet of a gas-liquid mixing pump, and the other path is connected to the inlet of a high-pressure water pump through a three-way valve, a liquid carbon dioxide storage tank, an electromagnetic booster pump and an intelligent heater are connected in sequence and then connected to the air inlet of the gas-liquid mixing pump, the outlet of the gas-liquid mixing pump is connected to the inlet of the high-pressure water pump through a three-way valve, a high-pressure heat-resistant insulation pipe 6 connected to the outlet of the high-pressure water pump extends into the water and gas injection borehole and is connected to a strong hydraulic cutting mechanism; the water and gas injection borehole is connected to a drainage pipe; the pressure relief borehole is connected to an extraction pipe. Method: establish a system connection; drill a borehole; use liquid water to make a seam; use two mixed media to perform a wetting operation. The system and method can form directional fractures with better ductility and larger cutting distance inside the coal body, and can significantly improve the injectability of the coal seam.

Description

Technical Field

[0001] The invention belongs to the technical field of coal seam wetting, and in particular relates to a system and method for enhancing the injectability of coal seams with a gas-water miscible medium. Background Art

[0002] During the mining process of underground coal mines, disasters such as high dust concentration, excessive gas, coal and gas outbursts, etc. are usually encountered, which poses a severe challenge to the safe and efficient mining of coal. Improving the injectability of coal seams is an effective way to suppress the high concentration of coal dust during mining, thereby effectively improving the underground working environment, which is beneficial to ensuring the health of miners, especially reducing the incidence of occupational diseases such as pneumoconiosis. At the same time, it has a significant effect on reducing the probability of dynamic disasters such as gas outbursts, coal and gas outbursts, etc.

[0003] In recent years, domestic and foreign scholars have conducted a lot of research on improving the injectability of coal seams. Ultra-high pressure hydraulic measures, chemical modification of coal bodies and other methods to improve the injectability of coal seams have been applied in production. However, ultra-high pressure hydraulic measures have high energy consumption, complex pipelines and high equipment requirements. Although they can create new fracture networks and expand the original network, their cutting distance is limited and cannot significantly increase the impact range of coal seam injectability. Chemical modification of coal bodies to increase the proportion of hydrophilic substances in coal can improve the injectability of coal seams to a certain extent, but chemical reagents often pollute groundwater and the by-products produced are not conducive to subsequent coal mining operations.

[0004] Therefore, it is urgent to provide a system and method for enhancing the injectability of coal seams with a gas-water miscible medium, so as to significantly improve the injectability of coal seams. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a system and method for enhancing the injectability of coal seams by using a gas-water miscible medium. The system has a reasonable structure, diverse functions, and an ideal slitting effect. It can not only efficiently realize the slitting operation, but also efficiently wetting the coal body. The method has a simple implementation process and good environmental performance. It can form directional fractures with better ductility and larger slitting distance inside the coal body, and can significantly improve the injectability of the coal seam.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a system for enhancing the injectability of coal seams with gas-water miscible medium, including a water-injection and gas-injection drilling hole, a pressure-relieving drilling hole, a sealing device 1, a sealing device 2, a liquid water storage tank, a water pump, an intelligent heater 1, a liquid carbon dioxide storage tank, an electromagnetic booster pump, an intelligent heater 2, a gas-liquid mixing pump, a high-pressure water pump, an enhanced hydraulic cutting mechanism, a water storage tank, a gas extraction pump and an extraction pipe;

[0007] The water injection and gas injection boreholes and the pressure relief boreholes are arranged in the coal seam at intervals, the first hole sealer is sealed at the hole opening of the water injection and gas injection boreholes, and the second hole sealer is sealed at the hole opening of the pressure relief borehole;

[0008] The common high-pressure resistant pipeline of the water pump is connected to the outlet end of the liquid water storage tank, and the inlet end of the intelligent heater 1 is connected to the outlet end of the water pump through the common high-pressure resistant pipeline and the inlet end of the three-way valve 1 through the high-pressure resistant insulation pipeline 1;

[0009] The inlet end of the electromagnetic booster pump is connected to the outlet end of the liquid carbon dioxide storage tank through a common high-pressure resistant pipeline connected in series with valve 2, and the inlet end of the second intelligent heater is connected to the outlet end of the electromagnetic booster pump through a common high-pressure resistant pipeline connected in series with pressure gauge 2;

[0010] The liquid inlet of the gas-liquid mixing pump is connected to the first outlet end of the three-way valve 1 through the high-pressure resistant heat-insulated pipe 2 connected in series with the one-way valve 1, and the gas inlet of the gas-liquid mixing pump is connected to the outlet end of the intelligent heater 2 through the high-pressure resistant heat-insulated pipe 3 connected in series with the valve 3;

[0011] The inlet end of the high-pressure water pump is connected to the outlet end of the three-way valve 2 through a common high-pressure resistant pipeline, the first inlet end of the three-way valve 2 is connected to the outlet end of the gas-liquid mixing pump through a high-pressure resistant heat-insulated pipeline 4 connected in series with a one-way valve 3, and the second inlet end of the three-way valve 2 is connected to the second outlet end of the three-way valve 1 through a high-pressure resistant heat-insulated pipeline 5 connected in series with a one-way valve 2; the outlet end of the high-pressure water pump is connected to the inlet end of the high-pressure resistant heat-insulated pipeline 6, and the outlet end of the high-pressure resistant heat-insulated pipeline 6 passes through the hole sealer 1 and extends to a position close to the bottom of the water and gas injection borehole;

[0012] The enhanced hydraulic slotting mechanism comprises a rotatable high-pressure joint, a small motor, a transmission shaft and a transmission chain; the rotatable high-pressure joint is a straight-cylinder structure, the top of which is closed, and the top of which is evenly connected to a plurality of high-pressure nozzles in communication with its inner cavity in the circumferential direction; the bottom end of the rotatable high-pressure joint is open, and is rotatably sleeved on the outside of the six outlet ends of the high-pressure insulation pipe through a pressure-resistant bearing; a driven sprocket is fixedly sleeved on the outside of the middle section of the rotatable high-pressure joint; one end of the transmission shaft is connected to the output shaft of the small motor, and the other end thereof passes through a hole sealer and extends into the interior of the water and air injection borehole, and a driving sprocket is fixedly sleeved on the part corresponding to the driven sprocket; the transmission chain is wound and connected to the outside of the driving sprocket and the driven sprocket;

[0013] The drainage pipe is connected in series with a valve 4, whose water outlet end is connected to the inlet end of the water storage tank, and whose inlet end passes through a hole sealer 1 and then extends into the interior of the water and air injection borehole;

[0014] The outlet end of the extraction pipe is connected to the inlet end of the gas extraction pump, and the inlet end thereof passes through the second hole sealer and then extends into the interior of the pressure relief borehole.

[0015] In the present invention, the intelligent heater 1 is arranged between the water pump and the liquid inlet of the gas-liquid mixing pump, which can facilitate heating of the liquid water, thereby facilitating improvement of the effect of the seam-making operation and the injection effect of the two-phase medium. The electromagnetic booster pump and the intelligent heater 2 are arranged in sequence between the liquid carbon dioxide storage tank and the gas-liquid mixing pump, which can pressurize and heat the output carbon dioxide gas in sequence, thereby supplying carbon dioxide gas of set pressure and temperature to the gas-liquid mixing pump, which is conducive to more uniform mixing with the heated liquid water, and helps the two-phase medium to better immerse into the coal body. The intelligent heater 1 is connected to the liquid inlet of the gas-liquid mixing pump and the second inlet end of the three-way valve 2 through the three-way valve 1, and the outlet end of the three-way valve 2 is connected to the inlet end of the high-pressure water pump, and the first inlet end of the three-way valve 2 is connected to the outlet end of the gas-liquid mixing pump. In this way, two filling channels are formed. At the same time, the combined control of the three-way valves 1 and 2 can be used to conveniently switch the two filling channels. One of the filling channels can only realize the filling of heated liquid water. At this time, the passage between the inlet end of the three-way valve 1 and its second outlet end is controlled to be connected, and the passage between the outlet end of the three-way valve 2 and its second inlet end is controlled to be connected. The other filling channel The channel can add the heated hydraulic water and the carbon dioxide gas after heating and pressurization to the gas-liquid mixing pump at the same time for uniform mixing, so as to realize the filling of the two mixed media. At this time, by controlling the passage between the inlet end and one of the outlet ends of the three-way valve one to be connected, the heated water flows into the mixing chamber of the gas-liquid mixing pump through the liquid inlet, and by controlling the opening of valve three to make the carbon dioxide after heating and pressurization flow into the mixing chamber of the gas-liquid mixing pump through the air inlet, the mixing effect of the gas-liquid mixing pump is used to fully mix the two media, and then the passage between the first inlet end and the outlet end of the three-way valve two is controlled to be connected, so that the two mixed media can be supplied to the high-pressure water pump. Therefore, the setting of the two channels makes the system more flexible, and the filling method can be flexibly changed according to different working conditions to meet the different needs of different operation stages. One-way valve 1 is connected in series to high-pressure resistant thermal insulation pipe 2, and one-way valve 2 is connected in series to high-pressure resistant thermal insulation pipe 5, ensuring that the liquid water flowing out of three-way valve 1 can only flow into the liquid inlet of the gas-liquid mixing pump in one direction or can only flow to the second inlet end of three-way valve 2 in one direction, and will not flow back to the intelligent heater 1, effectively improving the water supply efficiency. One-way valve 3 is connected in series to high-pressure resistant thermal insulation pipe 4, which can ensure that the mixed two-phase medium can only flow to the inlet end of the high-pressure water pump in one direction, effectively improving the output efficiency of the two media. Through the setting of high-pressure resistant thermal insulation pipes, not only the safety of the high-pressure medium transportation process can be guaranteed, but also the heated medium can be effectively prevented from losing heat during transportation, causing energy waste, which is conducive to ensuring the subsequent operation effect.The high-pressure water pump is arranged on the downstream side of the gas-liquid mixing pump, and the high-pressure water pump can be used to perform secondary pressurization on the two mixed media, thereby effectively improving the wetting effect of the coal body and significantly improving the wetting efficiency. The rotatable high-pressure joint is mounted on the outside of the outlet end of the high-pressure insulation pipe six through a pressure-resistant bearing sleeve, which can ensure that the rotatable high-pressure joint can stably rotate with the high-pressure insulation pipe six as the rotation center during operation. One end of the transmission shaft is provided with a driving sprocket, and at the same time, a driven sprocket is provided on the outside of the middle section of the rotatable high-pressure joint. The driving sprocket and the driven sprocket are connected by a transmission chain, and the output shaft of the small motor is connected to the other end of the transmission shaft. In this way, the small electric drive transmission shaft can be used for high-speed transmission, and then the rotatable high-pressure joint is driven by the transmission chain to rotate at high speed around the outlet end of the high-pressure insulation pipe 6. Therefore, when the outlet end of the high-pressure insulation pipe 6 extends into the water injection and gas injection borehole, as long as the small motor is started synchronously during the process of supplying the medium to the high-pressure insulation pipe 6, the high-speed rotating rotatable high-pressure joint can be used to perform a strong seam making operation, which is conducive to obtaining a crack with a better cutting distance, and at the same time, it can effectively improve the strong injection effect of the two mixed media. One end of the drainage pipe connected to the water storage tank is extended into the water injection and gas injection borehole, so as to collect the residual water in the hole and transport it to the water storage tank for storage, which can avoid the residual water in the hole affecting the ratio of the subsequent injection of the gas-liquid two-phase medium, and thus ensure the subsequent wetting effect of the coal body. The pressure relief borehole and the water and gas injection borehole are opened in the coal seam at intervals, and one end of the extraction pipe connected to the gas extraction pump is inserted into the pressure relief borehole after passing through the sealing device 2, so that the gas in the pressure relief borehole can be extracted by the gas extraction pump, thereby increasing the negative pressure in the coal seam, which is conducive to significantly improving the injection effect of the two media in the water and gas injection borehole, and further improving the effect of wetting the coal body. The system has a reasonable structure and various functions, and can not only efficiently realize the seam making operation, but also efficiently wet the coal body.

[0016] Furthermore, in order to be able to check the pressure conditions in the water injection and gas injection borehole in real time during the operation to effectively ensure the safety factor during the operation, a pressure gauge is also included. The pressure detection pipeline connected to the pressure gauge passes through the hole sealer and extends into the interior of the water injection and gas injection borehole.

[0017] Furthermore, in order to better speed up and pressurize the sprayed liquid or gas-liquid two-phase medium, the high-pressure nozzle includes a nozzle body and a connecting flange. The nozzle body is a variable diameter structure, and a first-level speed-increasing chamber and a second-level speed-increasing chamber are provided at its axis center. A liquid inlet connected to the end of the first-level speed-increasing chamber is provided at its end axis center, and a jewel jet port connected to the head end of the second-level speed-increasing chamber is provided at its head end axis center. The connecting flange is fixedly mounted on the outside of the end of the nozzle body, and the high-pressure nozzle is fixedly connected to the rotatable high-pressure joint through the connecting flange.

[0018] Furthermore, in order to effectively avoid the loss of heat in the high-pressure insulated pipe to improve the insulation effect, the high-pressure insulated pipe one, the high-pressure insulated pipe two, the high-pressure insulated pipe three, the high-pressure insulated pipe four, the high-pressure insulated pipe five and the high-pressure insulated pipe six have the same structure, which are all composed of an inner layer of high-pressure resistant corrosion-resistant pipe and an outer layer of insulated pipe, the outer layer of insulated pipe is nested on the outside of the inner layer of high-pressure resistant corrosion-resistant pipe, and a vacuum cavity is formed in the part between the outer layer of insulated pipe and the inner layer of high-pressure resistant corrosion-resistant pipe, and a sealing ring groove is provided at the connection between the two ends of the outer layer of insulated pipe and the inner layer of high-pressure resistant corrosion-resistant pipe, and a sealing ring is mounted on the sealing ring groove.

[0019] Furthermore, in order to efficiently utilize the pressure relief borehole to provide negative pressure to the water and gas injection borehole, the direction and depth of the pressure relief borehole and the water and gas injection borehole are consistent.

[0020] Preferably, the liquid water storage tank is a horizontal liquid water storage tank, and the liquid carbon dioxide storage tank is a horizontal liquid carbon dioxide storage tank.

[0021] The present invention also provides a method for enhancing coal seam injectability by using a gas-water miscible medium, and adopts a system for enhancing coal seam injectability by using a gas-water miscible medium, and the specific steps are as follows:

[0022] Step 1: Arrange liquid water storage tanks, water pumps, intelligent heater 1, liquid carbon dioxide storage tanks, electromagnetic booster pumps, intelligent heater 2, gas-liquid mixing pumps, high-pressure water pumps, enhanced hydraulic cutting mechanisms, water tanks, gas extraction pumps and extraction pipes near the target area;

[0023] Step 2: Use a plurality of common pressure-resistant pipes to respectively connect the inlet of the water pump and the outlet of the liquid water storage tank, connect the inlet of the intelligent heater 1 and the inlet of the water pump and the outlet of the liquid carbon dioxide storage tank, connect the inlet of the intelligent heater 2 and the outlet of the electromagnetic booster pump, and connect the inlet of the high-pressure water pump and the outlet of the three-way valve 2; use a high-pressure heat-resistant insulation pipe 1 to connect the inlet of the three-way valve 1 and the outlet of the intelligent heater 1, use a high-pressure heat-resistant insulation pipe 2 to connect the first outlet of the three-way valve 1 and the liquid inlet of the gas-liquid mixing pump, and connect the high-pressure heat-resistant insulation pipe 2 to the inlet of the gas-liquid mixing pump. Connect one-way valve one in series on pipe two, connect the air inlet of the gas-liquid mixing pump and the outlet of the intelligent heater two by using high-pressure heat-resistant insulation pipe three, connect valve three in series on high-pressure heat-resistant insulation pipe three, connect the first inlet end of three-way valve two and the outlet of the gas-liquid mixing pump by using high-pressure heat-resistant insulation pipe four, connect one-way valve three in series on high-pressure heat-resistant insulation pipe four, connect the second inlet end of three-way valve two and the second outlet end of three-way valve one by using high-pressure heat-resistant insulation pipe five, and connect one-way valve two in series on high-pressure heat-resistant insulation pipe five; connect the inlet end of high-pressure heat-resistant insulation pipe six to the outlet of the high-pressure water pump;

[0024] One end of the transmission shaft is connected to the output shaft of the small motor, and a driving sprocket is fixedly mounted on the outside of the other end, and a driven sprocket is fixedly mounted on the outside of the middle section of the rotatable high-pressure joint, and a transmission chain is wound around and connected to the outside of the driving sprocket and the driven sprocket to form an enhanced hydraulic slit mechanism; the water inlet end of the rotatable high-pressure joint is rotatably mounted on the outside of the six outlet ends of the high-pressure insulation pipe through a pressure-resistant bearing;

[0025] Step 3: Alternately drill water and gas injection boreholes and pressure relief boreholes in the coal seams of the target area;

[0026] Step 4: Extend the outlet end of the high-pressure insulation pipe 6 and the working part of the enhanced hydraulic cutting mechanism through the orifice to a position close to the bottom of the water injection and air injection borehole, extend the inlet end of the drainage pipe connected with the valve 4 through the orifice into the inside of the water injection and air injection borehole, connect the outlet end of the drainage pipe with the inlet end of the water storage tank, extend the pressure detection pipeline connected to the pressure gauge 1 through the orifice into the inside of the water injection and air injection borehole, and then use the hole sealer 1 to seal the orifice of the water injection and air injection borehole;

[0027] The inlet end of the extraction pipe is extended into the interior of the pressure relief borehole through the orifice, and the outlet end of the extraction pipe is connected to the inlet end of the gas extraction pump, and then the orifice of the pressure relief borehole is sealed with a second hole sealer;

[0028] Step 5: Open valve 1, start the water pump and intelligent heater 1, use intelligent heater 1 to heat the supplied liquid water, open the passage between the inlet end of three-way valve 1 and its second outlet end after the water temperature reaches the preset value A, open the passage between the second inlet end of three-way valve 2 and its outlet end, start the high-pressure water pump and the small motor, use the high-pressure water pump to pressurize the liquid water, and then supply the high-pressure and high-temperature water flow to the rotatable high-pressure joint through the high-pressure resistant insulation pipe 6, at the same time, use the high-speed rotating transmission shaft to drive the rotatable high-pressure joint to rotate at a high speed, use the rotating enhanced hydraulic cutting mechanism to perform a strong seam-making operation on the coal body, and after the seam-making operation is completed, turn off the high-pressure water pump and the small motor, and disconnect the passage between the inlet end of the three-way valve 1 and its second outlet end;

[0029] Step 6: Open valve 4, use the drainage pipe to drain the remaining water in the water and gas injection borehole, and use the water storage tank to collect it to ensure that the remaining water in the hole will not affect the ratio of the subsequent gas-liquid two-phase medium injection. After the drainage operation is completed, close valve 4;

[0030] Step 7: Open valve 2, start the electromagnetic booster pump and intelligent heater 2, use intelligent heater 2 to heat and pressurize the supplied carbon dioxide gas, open valve 3 after the pressure temperature reaches the preset value B, and at the same time, open the gas-liquid mixing pump, and open the passage between the inlet end of the three-way valve 1 and the first outlet end thereof, so that the heated water flow and the heated and pressurized carbon dioxide gas enter the mixing chamber of the gas-liquid mixing pump from the liquid inlet and the air inlet of the gas-liquid mixing pump respectively for full mixing, and after the mixing set time C is reached, start the high-pressure water pump and the small motor, and open the passage between the first inlet end of the three-way valve 2 and the outlet end thereof, use the high-pressure water pump to pressurize the fully mixed gas-liquid two-phase medium, and then use the high-pressure resistant insulation pipe 6 to supply the fully mixed gas-liquid two-phase medium to the rotatable high-pressure joint, and at the same time, use the high-speed rotating transmission shaft to drive the rotatable high-pressure joint to rotate at a high speed, and use the rotating enhanced hydraulic slitting mechanism to inject the gas-liquid two-phase medium into the gap formed in the coal body to enhance the injectability of the coal seam;

[0031] Step 8: Alternately drill water and gas injection holes and pressure relief holes in the coal seam in the target area, and repeat steps 3 to 7 in sequence until the operation in the target area is completed.

[0032] Furthermore, in order to allow the injected gas-liquid two-phase medium to diffuse to a wider range, in step seven, when the gas-liquid two-phase medium is injected into the cracks formed in the coal body, the gas extraction pump is simultaneously started.

[0033] In the present invention, firstly, the heated liquid water with a relatively high pressure is transported to the high-pressure heat-insulating pipe 6 through the pressurization of the high-pressure water pump, and the water is outputted to the inside of the water-injection and gas-injection drilling hole through the enhanced hydraulic slitting mechanism, so that the strong seam-making operation of the coal body can be efficiently realized, and then a directional fissure with good ductility and a larger slit distance can be formed inside the coal body, and then the supercritical carbon dioxide and water two-phase medium after heating and pressurization are fully mixed by the gas-liquid mixing pump, and then the secondary pressurization of the high-pressure water pump is used to transport it to the high-pressure heat-insulating pipe 6, and the water is further outputted to the inside of the water-injection and gas-injection drilling hole through the enhanced hydraulic slitting mechanism, thereby, the high solubility of supercritical carbon dioxide in water and the extremely strong diffusion ability after pressure relief can be used to effectively wet the coal body with more water, and while expanding the range of coal body fissures, more liquid water can be promoted to enter the deeper coal body fissure network, thereby significantly improving the injectability of the coal seam. At the same time, it is also conducive to reducing the probability of disasters such as dust and gas over-limit and coal and gas outbursts in the coal mining process. The method has a simple implementation process and good environmental protection, can form directional fractures with better ductility and larger cutting distance inside the coal body, and can significantly improve the injectability of the coal seam. Specifically, compared with the prior art, the present invention has the following advantages:

[0034] 1. By bringing more atomized water media into the microscopic pore structure of the coal body, the generation of dust during coal mining can be significantly inhibited, effectively improving the underground working environment, while ensuring the health of miners and reducing the probability of occupational diseases such as pneumoconiosis.

[0035] 2. By expanding the wetting range, the amount of gas outburst during the mining process is reduced, effectively preventing the occurrence of problems such as gas exceeding the limit at the working face that affect safe mining.

[0036] 3. By wetting the coal body, the probability of dynamic disasters such as coal and gas outbursts can be effectively reduced, fully ensuring the life safety of underground workers, and has wide promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the structure of the system for enhancing the injectability of coal seams by using a gas-water miscible medium in the present invention;

[0038] Figure 2 It is a structural schematic diagram of the enhanced hydraulic cutting mechanism of the present invention;

[0039] Figure 3 It is a structural schematic diagram of the high-pressure nozzle in the present invention;

[0040] Figure 4 It is a structural schematic diagram of the high-pressure resistant heat-insulating pipeline in the present invention.

[0041] In the figure: 1. Liquid water storage tank, 2. Valve 1, 3. Water pump, 4. Intelligent heater 1, 5. One-way valve 1, 6. Three-way valve 1, 7. One-way valve 2, 8. Gas-liquid mixing pump, 9. Three-way valve 2, 10. High-pressure water pump, 11. Strengthened hydraulic cutting mechanism, 11-1. Small motor, 11-2. Transmission shaft, 11-3. Driving sprocket, 11-4. Transmission chain, 11-5. Pressure-resistant bearing, 11-6. Rotatable high-pressure joint, 11-7. Driven sprocket, 12. Pressure gauge 1, 13. Sealing device 1, 14. High-pressure nozzle, 14-1. Liquid inlet, 14-2. First-stage speed-increasing chamber, 14-3. Second-stage speed-increasing chamber, 14-4. Gem jet nozzle, 14-5. Nozzle body, 14-6. Connecting flange, 15. Liquid dioxide Carbon storage tank, 16. Valve 2, 17. Electromagnetic booster pump, 18. Pressure gauge 2, 19. Intelligent heater 2, 20. Valve 3, 21. High-pressure thermal insulation pipe 1, 21-1. Inner high-pressure and corrosion-resistant pipe, 21-2. Outer thermal insulation pipe, 21-3. Vacuum chamber, 21-4. Sealing ring, 21-5. Sealing ring slot, 22. One-way valve 3, 23. Drain pipe, 24. Valve 4, 25. Water and gas injection drilling hole, 26. Coal seam, 27. Gas extraction pump, 28. Pressure relief drilling hole, 29. Extraction pipe, 30. Water storage tank, 31. Sealer 2, 32. High-pressure thermal insulation pipe 2, 33. High-pressure thermal insulation pipe 3, 34. High-pressure thermal insulation pipe 4, 35. High-pressure thermal insulation pipe 5, 36. High-pressure thermal insulation pipe 6. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the accompanying drawings.

[0043] like Figures 1 to 4 As shown, the present invention provides a system for enhancing the injectability of coal seams with gas-water miscible medium, including a water-injection and gas-injection borehole 25, a pressure-relieving borehole 28, a sealer 13, a sealer 21, a liquid water storage tank 1, a water pump 3, an intelligent heater 14, a liquid carbon dioxide storage tank 15, an electromagnetic booster pump 17, an intelligent heater 2 19, a gas-liquid mixing pump 8, a high-pressure water pump 10, an enhanced hydraulic cutting mechanism 11, a water storage tank 30, a gas extraction pump 27 and an extraction pipe 29;

[0044] The water injection and gas injection borehole 25 and the pressure relief borehole 28 are arranged in the coal seam 26 at intervals. As a preferred embodiment, the pressure relief borehole 28 is adjacent to the water injection and gas injection borehole 25. The hole sealer 13 is sealed at the orifice of the water injection and gas injection borehole 25, and the hole sealer 2 31 is sealed at the orifice of the pressure relief borehole 28.

[0045] The inlet end of the water pump 3 is connected to the outlet end of the liquid water storage tank 1 through a common high-pressure resistant pipeline connected in series with a valve 2, the inlet end of the intelligent heater 4 is connected to the outlet end of the water pump 3 through a common high-pressure resistant pipeline, and the outlet end of the intelligent heater 4 is connected to the inlet end of the three-way valve 6 through a high-pressure resistant insulation pipe 21;

[0046] The inlet end of the electromagnetic booster pump 17 is connected to the outlet end of the liquid carbon dioxide storage tank 15 through an ordinary high-pressure resistant pipeline connected in series with a valve 2 16, and the inlet end of the intelligent heater 2 19 is connected to the outlet end of the electromagnetic booster pump 17 through an ordinary high-pressure resistant pipeline connected in series with a pressure gauge 2 18; the pressure gauge 2 18 can facilitate intuitive observation of the pressure of the pressurized carbon dioxide gas, and thus can facilitate timely adjustment of the working pressure of the electromagnetic booster pump 17.

[0047] The liquid inlet of the gas-liquid mixing pump 8 is connected to the first outlet end of the three-way valve 6 through the high-pressure resistant heat-insulated pipe 32 connected in series with the one-way valve 5, and the air inlet of the gas-liquid mixing pump 8 is connected to the outlet end of the intelligent heater 2 19 through the high-pressure resistant heat-insulated pipe 3 33 connected in series with the valve 3 20;

[0048] The inlet end of the high-pressure water pump 10 is connected to the outlet end of the three-way valve 29 through a common high-pressure resistant pipeline, the first inlet end of the three-way valve 29 is connected to the outlet end of the gas-liquid mixing pump 8 through a high-pressure resistant heat-insulated pipe 4 34 connected in series with a one-way valve 3 22, and the second inlet end of the three-way valve 29 is connected to the second outlet end of the three-way valve 1 6 through a high-pressure resistant heat-insulated pipe 5 35 connected in series with a one-way valve 2 7; the outlet end of the high-pressure water pump 10 is connected to the inlet end of the high-pressure resistant heat-insulated pipe 6 36, and the outlet end of the high-pressure resistant heat-insulated pipe 6 36 passes through the hole sealer 13 and extends to a position close to the bottom of the water and gas injection borehole 25;

[0049] The enhanced hydraulic slitting mechanism 11 includes a rotatable high-pressure joint 11-6, a small motor 11-1, a transmission shaft 11-2 and a transmission chain 11-4; the rotatable high-pressure joint 11-6 is a straight-cylinder structure, the top of which is closed, and the top is evenly connected to a plurality of high-pressure nozzles 14 in communication with its inner cavity in the circumferential direction; the bottom end of the rotatable high-pressure joint 11-6 is open, and is rotatably sleeved on the outside of the outlet end of the high-pressure insulation pipe 636 through a pressure-resistant bearing 11-5; a driven sprocket 11-7 is fixedly sleeved on the outside of the middle section of the rotatable high-pressure joint 11-6; one end of the transmission shaft 11-2 is connected to the output shaft of the small motor 11-1, and the other end thereof passes through a sealing device 13 and extends into the interior of the water and gas injection borehole 25, and a driving sprocket 11-3 is fixedly sleeved on the part corresponding to the driven sprocket 11-7; the transmission chain 11-4 is wound and connected to the outside of the driving sprocket 11-3 and the driven sprocket 11-7;

[0050] The drain pipe 23 is connected in series with a valve 24, whose water outlet is connected to the inlet of the water storage tank 30, and whose inlet passes through the hole sealer 13 and then extends into the water and air injection borehole 25;

[0051] The outlet end of the extraction pipe 29 is connected to the inlet end of the gas extraction pump 27 , and the inlet end thereof passes through the second sealing device 31 and then extends into the interior of the pressure relief borehole 28 .

[0052] In the present invention, the intelligent heater 1 is arranged between the water pump and the liquid inlet of the gas-liquid mixing pump, which can facilitate heating of the liquid water, thereby facilitating improvement of the effect of the seam-making operation and the injection effect of the two-phase medium. The electromagnetic booster pump and the intelligent heater 2 are arranged in sequence between the liquid carbon dioxide storage tank and the gas-liquid mixing pump, which can pressurize and heat the output carbon dioxide gas in sequence, thereby supplying carbon dioxide gas of set pressure and temperature to the gas-liquid mixing pump, which is conducive to more uniform mixing with the heated liquid water, and helps the two-phase medium to better immerse into the coal body. The intelligent heater 1 is connected to the liquid inlet of the gas-liquid mixing pump and the second inlet end of the three-way valve 2 through the three-way valve 1, and the outlet end of the three-way valve 2 is connected to the inlet end of the high-pressure water pump, and the first inlet end of the three-way valve 2 is connected to the outlet end of the gas-liquid mixing pump. In this way, two filling channels are formed. At the same time, the combined control of the three-way valves 1 and 2 can be used to conveniently switch the two filling channels. One of the filling channels can only realize the filling of heated liquid water. At this time, the passage between the inlet end of the three-way valve 1 and its second outlet end is controlled to be connected, and the passage between the outlet end of the three-way valve 2 and its second inlet end is controlled to be connected. The other filling channel The channel can add the heated hydraulic water and the carbon dioxide gas after heating and pressurization to the gas-liquid mixing pump at the same time for uniform mixing, so as to realize the filling of the two mixed media. At this time, by controlling the passage between the inlet end and one of the outlet ends of the three-way valve one to be connected, the heated water flows into the mixing chamber of the gas-liquid mixing pump through the liquid inlet, and by controlling the opening of valve three to make the carbon dioxide after heating and pressurization flow into the mixing chamber of the gas-liquid mixing pump through the air inlet, the mixing effect of the gas-liquid mixing pump is used to fully mix the two media, and then the passage between the first inlet end and the outlet end of the three-way valve two is controlled to be connected, so that the two mixed media can be supplied to the high-pressure water pump. Therefore, the setting of the two channels makes the system more flexible, and the filling method can be flexibly changed according to different working conditions to meet the different needs of different operation stages. One-way valve 1 is connected in series to high-pressure resistant thermal insulation pipe 2, and one-way valve 2 is connected in series to high-pressure resistant thermal insulation pipe 5, ensuring that the liquid water flowing out of three-way valve 1 can only flow into the liquid inlet of the gas-liquid mixing pump in one direction or can only flow to the second inlet end of three-way valve 2 in one direction, and will not flow back to the intelligent heater 1, effectively improving the water supply efficiency. One-way valve 3 is connected in series to high-pressure resistant thermal insulation pipe 4, which can ensure that the mixed two-phase medium can only flow to the inlet end of the high-pressure water pump in one direction, effectively improving the output efficiency of the two media. Through the setting of high-pressure resistant thermal insulation pipes, not only the safety of the high-pressure medium transportation process can be guaranteed, but also the heated medium can be effectively prevented from losing heat during transportation, causing energy waste, which is conducive to ensuring the subsequent operation effect.The high-pressure water pump is arranged on the downstream side of the gas-liquid mixing pump, and the high-pressure water pump can be used to perform secondary pressurization on the two mixed media, thereby effectively improving the wetting effect of the coal body and significantly improving the wetting efficiency. The rotatable high-pressure joint is mounted on the outside of the outlet end of the high-pressure insulation pipe six through a pressure-resistant bearing sleeve, which can ensure that the rotatable high-pressure joint can stably rotate with the high-pressure insulation pipe six as the rotation center during operation. One end of the transmission shaft is provided with a driving sprocket, and at the same time, a driven sprocket is provided on the outside of the middle section of the rotatable high-pressure joint. The driving sprocket and the driven sprocket are connected by a transmission chain, and the output shaft of the small motor is connected to the other end of the transmission shaft. In this way, the small electric drive transmission shaft can be used for high-speed transmission, and then the rotatable high-pressure joint is driven by the transmission chain to rotate at high speed around the outlet end of the high-pressure insulation pipe 6. Therefore, when the outlet end of the high-pressure insulation pipe 6 extends into the water injection and gas injection borehole, as long as the small motor is started synchronously during the process of supplying the medium to the high-pressure insulation pipe 6, the high-speed rotating rotatable high-pressure joint can be used to perform a strong seam making operation, which is conducive to obtaining a crack with a better cutting distance, and at the same time, it can effectively improve the strong injection effect of the two mixed media. One end of the drainage pipe connected to the water storage tank is extended into the water injection and gas injection borehole, so as to collect the residual water in the hole and transport it to the water storage tank for storage, which can avoid the residual water in the hole affecting the ratio of the subsequent injection of the gas-liquid two-phase medium, and thus ensure the subsequent wetting effect of the coal body. The pressure relief borehole and the water and gas injection borehole are opened in the coal seam at intervals, and one end of the extraction pipe connected to the gas extraction pump is inserted into the pressure relief borehole after passing through the sealing device 2, so that the gas in the pressure relief borehole can be extracted by the gas extraction pump, thereby increasing the negative pressure in the coal seam, which is conducive to significantly improving the injection effect of the two media in the water and gas injection borehole, and further improving the effect of wetting the coal body. The system has a reasonable structure and various functions, and can not only efficiently realize the seam making operation, but also efficiently wet the coal body.

[0053] In order to be able to check the pressure conditions in the water injection and gas injection borehole in real time during the operation process and to effectively ensure the safety factor during the operation process, a pressure gauge 12 is also included. The pressure detection pipeline connected to the pressure gauge 12 passes through the hole sealer 13 and extends into the water injection and gas injection borehole 25.

[0054] In order to better speed up and pressurize the sprayed liquid or gas-liquid two-phase medium, the high-pressure nozzle 14 includes a nozzle body 14-5 and a connecting flange 14-6. The nozzle body 14-5 is a variable diameter structure, and its axis is provided with a connected first-level speed-increasing chamber 14-2 and a second-level speed-increasing chamber 14-3, and its end axis is provided with a liquid inlet 14-1 connected to the end of the first-level speed-increasing chamber 14-2, and its head end axis is provided with a jewel jet port 14-4 connected to the head end of the second-level speed-increasing chamber 14-3. The connecting flange 14-6 is fixedly mounted on the outside of the end of the nozzle body 14-5, and the high-pressure nozzle 14 is fixedly connected to the rotatable high-pressure joint 11-6 through the connecting flange 14-6.

[0055] In order to effectively avoid the loss of heat in the high-pressure insulated pipe and improve the insulation effect, the high-pressure insulated pipe 1 21, the high-pressure insulated pipe 2 32, the high-pressure insulated pipe 3 33, the high-pressure insulated pipe 4 34, the high-pressure insulated pipe 5 35 and the high-pressure insulated pipe 6 36 have the same structure, which are all composed of an inner layer of high-pressure resistant and corrosion-resistant pipe 21-1 and an outer layer of insulated pipe 21-2, the outer layer of insulated pipe 21-2 is nested on the outside of the inner layer of high-pressure resistant and corrosion-resistant pipe 21-1, and a vacuum chamber 21-3 is formed between the outer layer of insulated pipe 21-2 and the inner layer of high-pressure resistant and corrosion-resistant pipe 21-1, and a sealing ring groove 21-5 is provided at the connection between the two ends of the outer layer of insulated pipe 21-2 and the inner layer of high-pressure resistant and corrosion-resistant pipe 21-1, and a sealing ring 21-4 is mounted on the sealing ring groove 21-5.

[0056] In order to efficiently utilize the pressure relief borehole to provide negative pressure to the water and gas injection borehole, the direction and depth of the pressure relief borehole 28 and the water and gas injection borehole 25 are consistent.

[0057] As a preference, the liquid water storage tank 1 is a horizontal liquid water storage tank, and the liquid carbon dioxide storage tank 15 is a horizontal liquid carbon dioxide storage tank.

[0058] The present invention also provides a method for enhancing coal seam injectability by using a gas-water miscible medium, and adopts a system for enhancing coal seam injectability by using a gas-water miscible medium, and the specific steps are as follows:

[0059] Step 1: Arrange liquid water storage tank 1, water pump 3, intelligent heater 1 4, liquid carbon dioxide storage tank 15, electromagnetic booster pump 17, intelligent heater 2 19, gas-liquid mixing pump 8, high-pressure water pump 10, enhanced hydraulic cutting mechanism 11, water storage tank 30, gas extraction pump 27 and extraction pipe 29 near the target area;

[0060] Step 2: Use a plurality of common pressure-resistant pipes to respectively connect the inlet end of the water pump 3 and the outlet end of the liquid water storage tank 1, connect the inlet end of the intelligent heater 4 and the outlet end of the water pump 3, connect the inlet end of the electromagnetic booster pump 17 and the outlet end of the liquid carbon dioxide storage tank 15, connect the inlet end of the intelligent heater 19 and the outlet end of the electromagnetic booster pump 17, and connect the inlet end of the high-pressure water pump 10 and the outlet end of the three-way valve 29; use a high-pressure resistant heat-insulated pipe 21 to connect the inlet end of the three-way valve 6 and the outlet end of the intelligent heater 4, use a high-pressure resistant heat-insulated pipe 232 to connect the first outlet end of the three-way valve 6 and the liquid inlet of the gas-liquid mixing pump 8, and connect the high-pressure resistant heat-insulated pipe 233 to the high-pressure resistant heat-insulated pipe 234. A one-way valve 15 is connected in series to the second heat-insulated pipe 32, and a high-pressure heat-insulated pipe 33 is used to connect the air inlet of the gas-liquid mixing pump 8 and the outlet of the intelligent heater 2 19, and a valve 3 20 is connected in series to the high-pressure heat-insulated pipe 3 33, and a high-pressure heat-insulated pipe 4 34 is used to connect the first inlet end of the three-way valve 2 9 and the outlet end of the gas-liquid mixing pump 8, and a one-way valve 3 22 is connected in series to the high-pressure heat-insulated pipe 4 34, and a high-pressure heat-insulated pipe 5 35 is used to connect the second inlet end of the three-way valve 2 9 and the second outlet end of the three-way valve 1 6, and a one-way valve 2 7 is connected in series to the high-pressure heat-insulated pipe 5 35; the inlet end of the high-pressure heat-insulated pipe 6 36 is connected to the outlet end of the high-pressure water pump 10;

[0061] One end of the transmission shaft 11-2 is connected to the output shaft of the small motor 11-1, and a driving sprocket 11-3 is fixedly mounted on the other end thereof, and a driven sprocket 11-7 is fixedly mounted on the outside of the middle section of the rotatable high-pressure joint 11-6, and a transmission chain 11-4 is wound around and connected to the outside of the driving sprocket 11-3 and the driven sprocket 11-7 to assemble and form a reinforced hydraulic slitting mechanism 11; the water inlet end of the rotatable high-pressure joint 11-6 is rotatably mounted on the outside of the outlet end of the high-pressure insulation pipe 636 through a pressure-resistant bearing 11-5;

[0062] Step 3: alternately drilling water and gas injection boreholes 25 and pressure relief boreholes 28 in the coal seam 26 in the target area;

[0063] Step 4: Extend the outlet end of the high-pressure heat-insulated pipe 6 36 and the working part of the enhanced hydraulic cutting mechanism 11 through the orifice to a position close to the bottom of the water-injection and air-injection borehole 25, extend the inlet end of the drain pipe 23 connected in series with the valve 4 24 through the orifice into the interior of the water-injection and air-injection borehole 25, connect the outlet end of the drain pipe 23 to the inlet end of the water storage tank 30, extend the pressure detection pipeline connected to the pressure gauge 12 through the orifice into the interior of the water-injection and air-injection borehole 25, and then use the hole sealer 13 to seal the orifice of the water-injection and air-injection borehole 25;

[0064] The inlet end of the extraction pipe 29 is extended into the pressure relief borehole 28 through the orifice, and the outlet end of the extraction pipe 29 is connected to the inlet end of the gas extraction pump 27, and then the orifice of the pressure relief borehole 28 is blocked by using the hole sealer 31;

[0065] Step 5: Open valve 12, start the water pump 3 and the intelligent heater 14, use the intelligent heater 4 to heat the supplied liquid water, and when the water temperature reaches the preset value A, open the passage between the inlet end of the three-way valve 16 and its second outlet end, keep the passage between the inlet end of the three-way valve 16 and its first outlet end disconnected, open the passage between the second inlet end of the three-way valve 29 and its outlet end, keep the passage between the first inlet end of the three-way valve 29 and its outlet end disconnected, and start the high-pressure water pump 10 and the small motor 11-1, use the high-pressure water pump 10 to pressurize the liquid water, and then supply the high-pressure and high-temperature water flow to the rotatable high-pressure joint 11-6 through the high-pressure resistant heat-insulated pipe 636, at the same time, use the high-speed rotating transmission shaft 11-2 to drive the rotatable high-pressure joint 11-6 to rotate at a high speed, use the rotating enhanced hydraulic cutting mechanism 11 to perform a strong seam-making operation on the coal body, and after the seam-making operation is completed, close the high-pressure water pump 10 and the small motor 11-1, and disconnect the passage between the inlet end of the three-way valve 16 and its second outlet end;

[0066] Step 6: Open the valve 4 24, use the drainage pipe 23 to drain the remaining water in the water and gas injection borehole 25, and use the water storage tank 30 to collect it to ensure that the remaining water in the hole will not affect the ratio of the gas-liquid two-phase medium injected later. After the drainage operation is completed, close the valve 4 24;

[0067] Step 7: Open valve 2 16, start electromagnetic booster pump 17 and intelligent heater 2 19, use intelligent heater 2 19 to heat and pressurize the supplied carbon dioxide gas, open valve 3 20 after the pressure temperature reaches the preset value B, and at the same time, start the gas-liquid mixing pump 8, and open the passage between the inlet end of the three-way valve 16 and its first outlet end, and disconnect the passage between the inlet end of the three-way valve 16 and its second outlet end, so that the heated water flow and the heated and pressurized carbon dioxide gas enter the mixing chamber of the gas-liquid mixing pump 8 from the liquid inlet and air inlet of the gas-liquid mixing pump 8 respectively for full mixing, and start the high pressure after the mixing setting time C is reached The water pump 10 and the small motor 11-1 are used to open the passage between the first inlet end and the outlet end of the three-way valve 29, and the passage between the second inlet end and the outlet end of the three-way valve 29 is disconnected. The gas-liquid two-phase medium after being fully mixed is pressurized for a second time by the high-pressure water pump 10, and then the gas-liquid two-phase medium after being fully mixed is supplied to the rotatable high-pressure joint 11-6 through the high-pressure resistant heat-insulated pipe 636. At the same time, the rotatable high-pressure joint 11-6 is driven to rotate at a high speed by the high-speed rotating transmission shaft 11-2, and the gas-liquid two-phase medium is injected into the gap formed in the coal body by the rotating enhanced hydraulic slotting mechanism 11, so as to enhance the injectability of the coal seam 26;

[0068] Step 8: Alternately drill water and gas injection boreholes 25 and pressure relief boreholes 28 in the coal seam 26 in the target area, and repeat steps 3 to 7 in sequence until the operation in the target area is completed.

[0069] In order to allow the injected gas-liquid two-phase medium to diffuse to a wider range, in step seven, when the gas-liquid two-phase medium is injected into the cracks formed in the coal body, the gas extraction pump 27 is simultaneously started.

[0070] In the present invention, firstly, the heated liquid water with a relatively high pressure is transported to the high-pressure heat-insulating pipe 6 through the pressurization of the high-pressure water pump, and the water is outputted to the inside of the water-injection and gas-injection drilling hole through the enhanced hydraulic slitting mechanism, so that the strong seam-making operation of the coal body can be efficiently realized, and then a directional fissure with good ductility and a larger slit distance can be formed inside the coal body, and then the supercritical carbon dioxide and water two-phase medium after heating and pressurization are fully mixed by the gas-liquid mixing pump, and then the secondary pressurization of the high-pressure water pump is used to transport it to the high-pressure heat-insulating pipe 6, and the water is further outputted to the inside of the water-injection and gas-injection drilling hole through the enhanced hydraulic slitting mechanism, thereby, the high solubility of supercritical carbon dioxide in water and the extremely strong diffusion ability after pressure relief can be used to effectively wet the coal body with more water, and while expanding the range of coal body fissures, more liquid water can be promoted to enter the deeper coal body fissure network, thereby significantly improving the injectability of the coal seam. At the same time, it is also conducive to reducing the probability of disasters such as dust and gas over-limit and coal and gas outbursts in the coal mining process. The method has a simple implementation process and good environmental protection, can form directional fractures with better ductility and larger cutting distance inside the coal body, and can significantly improve the injectability of the coal seam. Specifically, compared with the prior art, the present invention has the following advantages:

[0071] 1. By bringing more atomized water media into the microscopic pore structure of the coal body, the generation of dust during coal mining can be significantly inhibited, effectively improving the underground working environment, while ensuring the health of miners and reducing the probability of occupational diseases such as pneumoconiosis.

[0072] 2. By expanding the wetting range, the amount of gas outburst during the mining process is reduced, effectively preventing the occurrence of problems such as gas exceeding the limit at the working face that affect safe mining.

[0073] 3. By wetting the coal body, the probability of dynamic disasters such as coal and gas outbursts can be effectively reduced, fully ensuring the life safety of underground workers, and has wide promotion and application value.

Claims

1. A system for enhancing the injectability of a coal seam by using a gas-water miscible medium, comprising a water injection and gas injection borehole (25), a pressure relief borehole (28), a first sealer (13) and a second sealer (31), wherein the water injection and gas injection borehole (25) and the pressure relief borehole (28) are arranged in a coal seam (26) at intervals, the first sealer (13) is sealed at the orifice of the water injection and gas injection borehole (25), and the second sealer (31) is sealed at the orifice of the pressure relief borehole (28); characterized in that: It also includes a liquid water storage tank (1), a water pump (3), a first intelligent heater (4), a liquid carbon dioxide storage tank (15), an electromagnetic booster pump (17), a second intelligent heater (19), a gas-liquid mixing pump (8), a high-pressure water pump (10), an enhanced hydraulic cutting mechanism (11), a water storage tank (30), a gas extraction pump (27) and an extraction pipe (29); The inlet end of the water pump (3) is connected to the outlet end of the liquid water storage tank (1) via a common high-pressure resistant pipeline connected in series with a valve (2); the inlet end of the intelligent heater (4) is connected to the outlet end of the water pump (3) via a common high-pressure resistant pipeline; the outlet end of the intelligent heater (4) is connected to the inlet end of the three-way valve (6) via a high-pressure resistant heat-insulating pipeline (21); The inlet end of the electromagnetic booster pump (17) is connected to the outlet end of the liquid carbon dioxide storage tank (15) via a common high-pressure resistant pipeline connected in series with a second valve (16), and the inlet end of the second intelligent heater (19) is connected to the outlet end of the electromagnetic booster pump (17) via a common high-pressure resistant pipeline connected in series with a second pressure gauge (18); The liquid inlet of the gas-liquid mixing pump (8) is connected to the first outlet end of the three-way valve (6) through the high-pressure heat-insulating pipe (32) connected in series with the one-way valve (5), and the gas inlet of the gas-liquid mixing pump (8) is connected to the outlet end of the intelligent heater (19) through the high-pressure heat-insulating pipe (33) connected in series with the valve (20); The inlet end of the high-pressure water pump (10) is connected to the outlet end of the three-way valve (9) through a common high-pressure resistant pipeline; the first inlet end of the three-way valve (9) is connected to the outlet end of the gas-liquid mixing pump (8) through a high-pressure resistant heat-insulated pipeline (34) connected in series with a one-way valve (22); the second inlet end of the three-way valve (9) is connected to the second outlet end of the three-way valve (6) through a high-pressure resistant heat-insulated pipeline (35) connected in series with a one-way valve (7); the outlet end of the high-pressure water pump (10) is connected to the inlet end of the high-pressure resistant heat-insulated pipeline (36); the outlet end of the high-pressure resistant heat-insulated pipeline (36) passes through the hole sealer (13) and then extends to a position close to the bottom of the water and gas injection borehole (25); The enhanced hydraulic slotting mechanism (11) comprises a rotatable high-pressure joint (11-6), a small motor (11-1), a transmission shaft (11-2) and a transmission chain (11-4); the rotatable high-pressure joint (11-6) is a straight-cylindrical structure, the top end of which is closed, and the top end is evenly connected to a plurality of high-pressure nozzles (14) in communication with its inner cavity in the circumferential direction; the bottom end of the rotatable high-pressure joint (11-6) is open, and is rotatably mounted on the outlet end of the high-pressure insulation pipe (36) via a pressure-resistant bearing (11-5). The outside of the middle section of the rotatable high-pressure joint (11-6) is fixedly sleeved with a driven sprocket (11-7); one end of the transmission shaft (11-2) is connected to the output shaft of the small motor (11-1), and the other end thereof passes through a sealing device (13) and extends into the inside of the water-injection and air-injection drilling hole (25), and a driving sprocket (11-3) is fixedly sleeved on the part corresponding to the driven sprocket (11-7); the transmission chain (11-4) is wound and connected to the outside of the driving sprocket (11-3) and the driven sprocket (11-7); A valve four (24) is serially connected to the drainage pipe (23), the water outlet end of which is connected to the inlet end of the water storage tank (30), and the inlet end of which passes through the hole sealer one (13) and then extends into the water and air injection borehole (25); The outlet end of the extraction pipe (29) is connected to the inlet end of the gas extraction pump (27), and the inlet end thereof passes through the second hole sealer (31) and then extends into the interior of the pressure relief borehole (28).

2. The system for enhancing coal seam injectability by using gas-water miscible medium according to claim 1, characterized in that: It also includes a pressure gauge (12), wherein a pressure detection pipeline connected to the pressure gauge (12) passes through a hole sealer (13) and then extends into the interior of the water and gas injection borehole (25).

3. The system for enhancing coal seam injectability by using gas-water miscible medium according to claim 2, characterized in that: The high-pressure nozzle (14) comprises a nozzle body (14-5) and a connecting flange (14-6). The nozzle body (14-5) is a variable diameter structure, and is provided with a first-stage speed-increasing chamber (14-2) and a second-stage speed-increasing chamber (14-3) at its axis center. A liquid inlet (14-1) communicating with the end of the first-stage speed-increasing chamber (14-2) is provided at its end axis center, and a gem jet port (14-4) communicating with the head end of the second-stage speed-increasing chamber (14-3) is provided at its head axis center. The connecting flange (14-6) is fixedly sleeved on the outer side of the end of the nozzle body (14-5), and the high-pressure nozzle (14) is fixedly connected to a rotatable high-pressure joint (11-6) via the connecting flange (14-6).

4. The system for enhancing coal seam injectability by using gas-water miscible medium according to claim 3 is characterized in that: The high-pressure insulated pipe one (21), the high-pressure insulated pipe two (32), the high-pressure insulated pipe three (33), the high-pressure insulated pipe four (34), the high-pressure insulated pipe five (35) and the high-pressure insulated pipe six (36) have the same structure, and are all composed of an inner layer high-pressure resistant and corrosion-resistant pipe (21-1) and an outer layer insulated pipe (21-2), the outer layer insulated pipe (21-2) is nested on the outside of the inner layer high-pressure resistant and corrosion-resistant pipe (21-1), and a vacuum chamber (21-3) is formed between the outer layer insulated pipe (21-2) and the inner layer high-pressure resistant and corrosion-resistant pipe (21-1), and a sealing ring groove (21-5) is provided at the connection between the two ends of the outer layer insulated pipe (21-2) and the inner layer high-pressure resistant and corrosion-resistant pipe (21-1), and a sealing ring (21-4) is sleeved on the sealing ring groove (21-5).

5. The system for enhancing coal seam injectability by using gas-water miscible medium according to claim 4, characterized in that: The pressure relief borehole (28) and the water and gas injection borehole (25) have the same direction and depth.

6. The system for enhancing coal seam injectability by using gas-water miscible medium according to claim 5, characterized in that: The liquid water storage tank (1) is a horizontal liquid water storage tank, and the liquid carbon dioxide storage tank (15) is a horizontal liquid carbon dioxide storage tank.

7. A method for enhancing coal seam injectability by using gas-water miscible medium, using a system for enhancing coal seam injectability by using gas-water miscible medium as claimed in any one of claims 1 to 6, characterized in that: The specific steps are as follows: Step 1: Arrange a liquid water storage tank (1), a water pump (3), a first intelligent heater (4), a liquid carbon dioxide storage tank (15), an electromagnetic booster pump (17), a second intelligent heater (19), a gas-liquid mixing pump (8), a high-pressure water pump (10), an enhanced hydraulic cutting mechanism (11), a water storage tank (30), a gas extraction pump (27) and an extraction pipe (29) near the target area; Step 2: Use a plurality of common pressure-resistant pipes to respectively connect the inlet end of the water pump (3) and the outlet end of the liquid water storage tank (1), the inlet end of the intelligent heater 1 (4) and the outlet end of the water pump (3), the inlet end of the electromagnetic booster pump (17) and the outlet end of the liquid carbon dioxide storage tank (15), the inlet end of the intelligent heater 2 (19) and the outlet end of the electromagnetic booster pump (17), and the inlet end of the high-pressure water pump (10) and the outlet end of the three-way valve 2 (9); use a high-pressure resistant heat-insulated pipe 1 (21) to connect the inlet end of the three-way valve 1 (6) and the outlet end of the intelligent heater 1 (4), use a high-pressure resistant heat-insulated pipe 2 (32) to connect the first outlet end of the three-way valve 1 (6) and the liquid inlet of the gas-liquid mixing pump (8), and connect the high-pressure resistant heat-insulated pipe 1 (21) to the high-pressure resistant heat-insulated pipe 1 (32) A one-way valve (5) is connected in series to the second (32); a high-pressure heat-resistant insulated pipe (33) is used to connect the air inlet of the gas-liquid mixing pump (8) and the outlet of the second intelligent heater (19); a valve (20) is connected in series to the third (33); a high-pressure heat-resistant insulated pipe (4) is used to connect the first inlet of the three-way valve (9) and the outlet of the gas-liquid mixing pump (8); a one-way valve (22) is connected in series to the fourth (34); a high-pressure heat-resistant insulated pipe (5) is used to connect the second inlet of the three-way valve (9) and the second outlet of the three-way valve (6); and a one-way valve (7) is connected in series to the fifth (35); the inlet of the sixth (36) is connected to the outlet of the high-pressure water pump (10); One end of the transmission shaft (11-2) is connected to the output shaft of the small motor (11-1), and a driving sprocket (11-3) is fixedly mounted on the outside of the other end of the transmission shaft, and a driven sprocket (11-7) is fixedly mounted on the outside of the middle section of the rotatable high-pressure joint (11-6), and a transmission chain (11-4) is connected to the outside of the driving sprocket (11-3) and the driven sprocket (11-7) to form an enhanced hydraulic slitting mechanism (11); the water inlet end of the rotatable high-pressure joint (11-6) is rotatably mounted on the outside of the outlet end of the high-pressure insulation pipe (36) through a pressure-resistant bearing (11-5); Step 3: alternately drilling water and gas injection boreholes (25) and pressure relief boreholes (28) in the coal seam (26) in the target area; Step 4: Extend the outlet end of the high-pressure insulation pipe 6 (36) and the working part of the enhanced hydraulic cutting mechanism (11) through the orifice to a position close to the bottom of the water injection and air injection borehole (25), extend the inlet end of the drainage pipe (23) connected in series with the valve 4 (24) through the orifice into the interior of the water injection and air injection borehole (25), connect the outlet end of the drainage pipe (23) to the inlet end of the water storage tank (30), and then extend the pressure detection pipeline connected to the pressure gauge 1 (12) into the interior of the water injection and air injection borehole (25) through the orifice, and then use the hole sealer 1 (13) to seal the orifice of the water injection and air injection borehole (25); The inlet end of the extraction pipe (29) is extended into the interior of the pressure relief borehole (28) through the orifice, and the outlet end of the extraction pipe (29) is connected to the inlet end of the gas extraction pump (27), and then the orifice of the pressure relief borehole (28) is sealed using a second hole sealer (31); Step 5: Open valve 1 (2), start the water pump (3) and the intelligent heater 1 (4), use the intelligent heater 1 (4) to heat the supplied liquid water, and when the water temperature reaches the preset value A, open the passage between the inlet end of the three-way valve 1 (6) and its second outlet end, open the passage between the second inlet end of the three-way valve 2 (9) and its outlet end, and start the high-pressure water pump (10) and the small motor (11-1), use the high-pressure water pump (10) to pressurize the liquid water, and then supply the high-pressure and high-temperature water flow to the rotatable high-pressure joint (11-6) through the high-pressure resistant heat-insulated pipe 6 (36), and at the same time, use the high-speed rotating transmission shaft (11-2) to drive the rotatable high-pressure joint (11-6) to rotate at a high speed, and use the rotating enhanced hydraulic seam cutting mechanism (11) to perform a strong seam cutting operation on the coal body. After the seam cutting operation is completed, turn off the high-pressure water pump (10) and the small motor (11-1), and disconnect the passage between the inlet end of the three-way valve 1 (6) and its second outlet end; Step 6: Open valve 4 (24), use the drainage pipe (23) to drain the remaining water in the water and gas injection borehole (25), and use the water storage tank (30) to collect the remaining water in the borehole to ensure that the remaining water does not affect the ratio of the gas-liquid two-phase medium injected later. After the drainage operation is completed, close valve 4 (24); Step 7: Open valve 2 (16), start the electromagnetic booster pump (17) and the intelligent heater 2 (19), use the intelligent heater 2 (19) to heat and pressurize the supplied carbon dioxide gas, and open valve 3 (20) after the pressure temperature reaches the preset value B. At the same time, open the gas-liquid mixing pump (8), and open the passage between the inlet end of the three-way valve 1 (6) and its first outlet end, so that the heated water flow and the heated and pressurized carbon dioxide gas enter the mixing chamber of the gas-liquid mixing pump (8) from the liquid inlet and the air inlet of the gas-liquid mixing pump (8) respectively, and are fully mixed. After the mixing setting time C is reached, start the high-pressure water pump (8). The pump (10) and the small motor (11-1) are opened, and the passage between the first inlet end and the outlet end of the three-way valve 2 (9) is opened, and the fully mixed gas-liquid two-phase medium is pressurized for a second time by the high-pressure water pump (10), and the fully mixed gas-liquid two-phase medium is then supplied to the rotatable high-pressure joint (11-6) through the high-pressure resistant heat-insulated pipe 6 (36). At the same time, the rotatable high-pressure joint (11-6) is driven to rotate at a high speed by the high-speed rotating transmission shaft (11-2), and the gas-liquid two-phase medium is injected into the gap formed in the coal body by the rotating enhanced hydraulic slotting mechanism (11), so as to enhance the injectability of the coal seam (26); Step 8: Alternately drill water and gas injection boreholes (25) and pressure relief boreholes (28) in the coal seam (26) of the target area, and repeat steps 3 to 7 in sequence until the operation in the target area is completed.

8. According to the method for enhancing coal seam injectability using a gas-water miscible medium as claimed in claim 7, in step seven, when the gas-liquid two-phase medium is injected into the cracks formed in the coal body, the gas extraction pump (27) is started synchronously.

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