A hole protection system and method for coal seam cutting, compression and combined extraction

Abstract

The invention provides a hole protection system and method for coal seam cutting and pressure combined extraction. The system includes a hydraulic cutting subsystem, a hydraulic fracturing subsystem and a flexible hole protection system. The hydraulic cutting subsystem includes a high-pressure water jet generation system, a drill pipe and drilling tool system, a hole sealer, a gas-slag separator and a drilling rig, and the hydraulic fracturing subsystem includes an emulsification pump station, a water tank, a hole sealing device, a fracturing pipe string and a casing. The flexible hole protection system includes a front-end fixing device, a water injection support pipe, a flexible support I and a water injection connection section, wherein the hydraulic cutting subsystem and the hydraulic fracturing subsystem can orderly complete the regional joint permeability enhancement of the broken soft coal seam, and the permeability enhancement system has the advantages of a wide pressure relief range and accurate positioning. At the same time, the flexible hole protection system can promptly support the formed pressure relief space. The hole protection system and method can effectively increase the gas flow space and further significantly improve the gas extraction efficiency.

Description

Technical Field

[0001] The present invention relates to the field of coal mine gas prevention and control, and in particular to a hole protection system and method for coal seam cutting, compression and combined extraction. Background Art

[0002] As my country's coal mining gradually extends to deeper areas, broken, soft and low-permeability coal seams account for a large proportion of the mined coal seams, which are mainly characterized by broken coal bodies, poor permeability, high gas content and gas pressure, great difficulty in extraction and high cost of governance. At present, hydraulic pressure relief and permeability enhancement measures have become the main means of disaster prevention and control in coal mines. Common hydraulic measures include: hydraulic slitting, hydraulic fracturing, etc. Hydraulic fracturing has a large range of action and good permeability enhancement effect, but it is affected by the geological conditions of the coal seams. The direction of hydraulic fracturing crack extension is difficult to control, and the crack extension in the fracturing area lacks specificity. On the one hand, it is easy to form high stress concentration areas, and uneven fracturing is prone to "blind spots". On the other hand, the permeability enhancement effect is not significant in gas-rich areas at a long distance. The hydraulic slitting technology has accurate slitting positioning, and can quickly and effectively cut slits in local areas of coal seams, achieving fixed-point and precise permeability enhancement in gas-rich areas of coal seams, but the hydraulic slitting has a smaller impact range than hydraulic fracturing. The complex and changeable conditions of soft and broken coal seams bring great difficulties to drilling holes. The borehole deformation is large, and the hole wall is prone to instability and collapse under the influence of factors such as ground stress, gas pressure, and structural stress. At the same time, the traditional screen pipe hole protection method has the disadvantages of small screen pipe diameter and high cost, so that the implementation of existing borehole instability and collapse prevention and control technology lacks pertinence.

[0003] Therefore, for the treatment of coal and gas outbursts in coal seams, combined with the characteristics of broken and soft coal seams, it is urgent to develop a hole protection system and method for coal seam cutting, compression and combined extraction. Summary of the invention

[0004] The object of the present invention is to provide a hole protection system and method for coal seam cutting, compression and combined extraction, so as to solve the problems existing in the prior art.

[0005] The technical solution adopted to achieve the purpose of the present invention is as follows: a hole protection system for coal seam cutting, fracturing and combined extraction, including a hydraulic cutting subsystem, a hydraulic fracturing subsystem and a flexible hole protection system.

[0006] The hydraulic cutting subsystem comprises an ultra-high pressure water jet generating system, a drill pipe and drilling tool system, a hole sealer, a gas-slag separator and a drilling rig.

[0007] The ultra-high pressure water jet generation system includes an emulsification pump station and a water tank. The drill rod and drill tool system includes a drill rod, a drill bit and a high pressure water braid. The drill rod is a hollow round tube as a whole. The drill bit is provided with a radial nozzle and an axial nozzle for high pressure water jetting. The radial nozzle is arranged at the front end of the drill bit. The axial nozzle is arranged on the side wall of the drill bit. The drill bit is installed at the head end of the drill rod. The inner cavity of the drill bit is connected to the inner cavity of the drill rod. The input end of the high pressure water braid is connected to the emulsification pump station through a high pressure pipeline, and the output end is connected to the tail end of the drill rod.

[0008] The orifice sealer is a tubular body. The front end of the orifice sealer is open and fixed on the wall of the borehole, and the rear end is connected to the gas-slag separator. The drill rod extends into the borehole from the rear end of the orifice sealer. The gas-slag separator is connected to the gas extraction pipeline.

[0009] The hydraulic fracturing system includes an emulsification pump station, a water tank, a sealing device, a fracturing pipe string and a casing. The water tank and the emulsification pump are connected by a high-pressure hose. After the high-pressure water is generated, it enters the water volume regulating device through the high-pressure water pipe. The high-pressure water pipe is provided with a flow meter and a pressure gauge. The front section of the fracturing pipe string is connected to a high-pressure pipeline conversion joint.

[0010] The flexible hole protection system includes a front-end fixing device, a water injection support pipe and a flexible support I. A water injection hole is arranged on the pipe wall of the water injection support pipe. The front-end fixing device is connected and fixed to the head end of the water injection support pipe, and the tail end is connected to the hydraulic pump. The front-end fixing device has a supporting hook. The supporting hook adopts a compression spring structure. The water injection support pipe is arranged in the inner cavity of the drill rod. The front-end fixing device is arranged in the central hole of the drill bit. The supporting hook of the front-end fixing device is engaged with the inner wall of the central hole.

[0011] The flexible support I is a mesh structure. The flexible support I includes a plurality of annular support tubes arranged in sequence along the longitudinal direction. Each annular support tube includes a plurality of unit waves, and the unit waves are arranged in sequence along the circumferential direction. Two adjacent annular support tubes are distributed in mirror symmetry. Two adjacent annular support tubes are fixedly connected between two opposite wave peaks. The inner cavities of the two adjacent annular support tubes are connected. The inner cavities of the plurality of annular support tubes form a pipe network structure.

[0012] In a non-working state, the flexible support I in a compact state is sleeved on the pipe body of the water injection support pipe. The water injection hole is communicated with the inner cavity of the pipe network of the flexible support I.

[0013] The technical effects of the present invention are unquestionable:

[0014] A. According to the location of the gas-enriched zone, different permeability enhancement modes can be applied, and combined with flexible hole protection devices, it has an excellent gas extraction effect.

[0015] B. The flexible hole protection system can actively adapt to the shape of the seam groove in hydraulic cutting, realize the way of actively maintaining the seam groove, and the safety of the working surface can be better guaranteed; the bracket can be recycled and reused many times after the hole protection is completed, saving a lot of costs;

[0016] C. The system can be widely used in broken and soft coal seams under complex geological conditions, and can support fracturing drilling and cutting slots to further improve gas extraction efficiency;

[0017] D. The stability of the borehole and the slot can be guaranteed by the flexible support device. Compared with the passive hole protection of the traditional screen pipe, the hole protection range of the flexible support I is larger. The flexible hole protection can realize active hole protection when the deformation is small in the initial stage of borehole instability, maintain a more complete annular structure of the borehole, and reduce the supporting force required for hole protection. It can realize efficient and uniform permeability enhancement of coal seams with complex geological structures, improve the gas extraction efficiency of coal seams with complex geological structures, and thus achieve the purpose of effectively preventing and controlling gas disasters in coal seams with complex geological structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the integrated system of drilling, cutting and protection;

[0019] Figure 2 This is the contraction and expansion diagram of the flexible bracket;

[0020] Figure 3 It is a schematic diagram of the double-hole flexible system cutting and pressing combined with hole protection;

[0021] Figure 4 Schematic diagram of single-hole flexible system cutting and pressing combined with hole protection;

[0022] Figure 5 Flow chart of the construction of combined cutting and pressing hole protection. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0024] Embodiment 1:

[0025] The present embodiment provides a hole protection system for coal seam cutting, fracturing and combined extraction, including a hydraulic cutting subsystem, a hydraulic fracturing subsystem and a flexible hole protection system.

[0026] The hydraulic slotting subsystem includes an ultra-high pressure water jet generation system, a drill pipe and drill tool system, an orifice sealer, a gas-slag separator and a drilling rig. The ultra-high pressure water jet generation system includes an emulsification pump station and a water tank. The drill pipe and drill tool system includes a drill pipe, a drill bit and a high-pressure water braid. The drill pipe is a hollow round tube as a whole. The drill bit is provided with a radial nozzle and an axial nozzle for high-pressure water jetting. The radial nozzle is arranged at the front end of the drill bit. The axial nozzle is arranged at the side wall of the drill bit. The drill bit is installed at the head end of the drill pipe. The inner cavity of the drill bit is connected to the inner cavity of the drill pipe. The input end of the high-pressure water braid is connected to the emulsification pump station through a high-pressure pipeline, and the output end is connected to the tail end of the drill pipe. The orifice sealer is a tubular body. The front end of the orifice sealer is open and fixed on the wall of the borehole orifice, and the rear end is connected to the gas-slag separator. The drill pipe extends into the borehole from the rear end of the orifice sealer. The gas-slag separator is connected to the gas extraction pipeline. In the hydraulic cutting subsystem, the water tank and the emulsification pump are connected by a high-pressure hose. The pressure control device mainly adjusts and controls the water pressure through a stop valve. The pressure is displayed by a pressure gauge. The input end of the high-pressure water braid is connected to the emulsification pump through a high-pressure hose, and the output end is connected to the special sealed drill pipe arranged on the drilling rig. The drill pipe sections are connected by drill pipe connectors. The front section of the drill pipe is embedded with a drilling and cutting drill bit, and the drill bit is designed with a water outlet hole with a diameter of 5mm.

[0027] The hydraulic fracturing system includes an emulsification pump station, a water tank, a sealing device, a fracturing pipe string and a casing. The water tank and the emulsification pump are connected by a high-pressure hose. After the high-pressure water is generated, it enters the water volume regulating device through the high-pressure water pipe. The high-pressure water pipe is provided with a flow meter and a pressure gauge. The front section of the fracturing pipe string is connected to a high-pressure pipeline conversion joint. In the high-pressure water generating device of the hydraulic fracturing subsystem, the water tank and the emulsification pump are connected by a high-pressure hose. The pressure is mainly controlled by adjusting and controlling the water pressure through a stop valve, and the pressure is displayed by a pressure gauge. After the high-pressure water is generated, it enters the water volume regulating device through a high-pressure water pipe. This part is connected to a flow meter with a flow meter connecting valve on the high-pressure water pipe through a flow meter joint. At the same time, a pressure gauge with a pressure gauge connecting valve is also connected to the high-pressure water pipe through a pressure gauge connector. The plugging device is mainly composed of a grouting pipe, a first packer, a second packer, a one-way valve, a fracturing string, a high-pressure pipeline conversion joint, and a water outlet screen. The front section of the fracturing string is connected to the high-pressure pipeline conversion joint, and is connected to the second packer and the first packer in sequence.

[0028] The flexible hole protection system includes a front-end fixing device, a water injection support pipe and a flexible support I. A water injection hole is arranged on the pipe wall of the water injection support pipe. The front-end fixing device is connected and fixed to the head end of the water injection support pipe, and the tail end is connected to the hydraulic pump. The front-end fixing device has a supporting hook. The supporting hook adopts a compression spring structure. The water injection support pipe is arranged in the inner cavity of the drill rod. The front-end fixing device is arranged in the central hole of the drill bit. The supporting hook of the front-end fixing device is engaged with the inner wall of the central hole.

[0029] Flexible support around the drill hole such as Figure 2 As shown, the flexible support I is a mesh structure. The flexible support I includes a plurality of annular support tubes arranged in sequence along the longitudinal direction. Each annular support tube includes a plurality of unit waves, and the unit waves are arranged in sequence along the circumferential direction. Two adjacent annular support tubes are distributed in mirror symmetry. Two adjacent annular support tubes are fixedly connected between two opposite wave peaks. The inner cavities of the two adjacent annular support tubes are connected. The inner cavities of the plurality of annular support tubes form a pipe network structure.

[0030] In a non-working state, the flexible support I in a compact state is sleeved on the pipe body of the water injection support pipe. The water injection hole is communicated with the inner cavity of the pipe network of the flexible support I.

[0031] Embodiment 2:

[0032] The main structure of this embodiment is the same as that of embodiment 1, wherein the flexible bracket II2 is a flexible bracket that fits around the slot. Figure 1 As shown, the flexible support II2 includes annular tube I201 and annular tube II202, and a plurality of annular support tubes arranged between the annular tube I201 and the annular tube II202. Each annular support tube includes a plurality of unit waves, and the unit waves are arranged in sequence along the circumferential direction. The two adjacent annular support tubes are fixedly connected between the two opposite wave peaks. The inner cavity of the flexible support II2 is connected to the hydraulic pump. The inner cavity of the flexible support II2 is connected to the hydraulic pump. During operation, the fixed traction device drives the annular tube I201 and the annular tube II202 to approach each other, and the annular support tube is deformed and fits the slit.

[0033] The fixed traction device is mainly composed of a drainage valve body and an electromagnetic mechanism. It is mainly triggered by the electrode of the valve, thereby indirectly driving the electromagnet to loosen and complete the mechanical movement. The traction rail device is mainly distributed on the outer wall of the water injection support pipe and is composed of a transverse groove body. When working, the traction devices at both ends are triggered, and a contraction force from both sides to the inside is generated at the same time, and the flexible bracket II is driven to move to the slot and unfold with the help of the movement of the traction rail.

[0034] The flexible bracket I and the flexible bracket II2 are made of silicon bronze elastic alloy (Qsi1-3). Nickel-containing silicon bronze has high elastic properties and can be used to manufacture various springs working in corrosive media (such as well water, groundwater).

[0035] Embodiment 3:

[0036] The main structure of this embodiment is the same as that of embodiment 2. According to the location of the gas-enriched zone, in this embodiment, the gas-enriched zone is distributed around the borehole and is close to the borehole. The in-situ cutting-pressure combined permeability enhancement mode can be applied. The borehole is first arranged for cutting, and then the fracturing operation is further performed on the basis of the cutting drilling to enhance the long-distance extraction and permeability enhancement effect of the cutting drilling. Figure 3 The in-situ cutting-compression combined anti-reflection mode specifically includes the following steps:

[0037] a. After the drilling rig, pump box, connecting pipelines, etc. are transported to the construction site, they are installed and firmly supported, the pipelines are connected, the emulsion pump is laid, the high-pressure pipeline is laid, and the high-pressure pipeline is debugged. After the equipment installation and connection preparation work is completed, the inspection of related systems is completed.

[0038] b. Based on the anti-blowout design of the working face, construction and extraction drilling are carried out according to the preset slit drilling positions.

[0039] c. Connect the diamond composite drill bit and the hydraulic slit shallow spiral drill rod in sequence, install the hydraulic slit nozzle equipped with a nozzle on the front end of the high-pressure water jet drill rod, push the drill bit in, then connect the drill rod and the drill bit, push it into the drilling rig, turn on the drilling rig to make the drill rod rotate at a low speed, and use low-pressure water to drill the hole.

[0040] d. After the drill bit reaches the designed position, turn on the high-pressure water pump, and water enters the drill pipe through the ultra-high-pressure hose. Control the stop valve, adjust the pressure at the drilling rig end, and adjust the pressure valve to gradually increase the pressure of the jet system. After the pressure stabilizes, use the high-pressure water jet on the high-pressure nozzle to perform rotary cutting on the coal body on the borehole wall. The rotary cutting time for each cut is 20-25 minutes.

[0041] e. After the seam groove is formed, the drill bit and drill rod continue to retreat, expand the front section fixing device of the bracket, and leave the flexible support bracket and support tube in the borehole.

[0042] f. Control the stop valve to allow water to return to the water tank through the high-pressure water pipe and remove the drill rod at that location.

[0043] g. After the drill rod is withdrawn, the withdrawn drill rod is disassembled, the water injection support pipe is connected to the hydraulic pump, and hydraulic pressure is applied to the hole protection bracket. The traction device is turned on, the traction device where the slot is located is triggered, and the flexible bracket I is converged around the slot through the movement of the slide rail.

[0044] h. Adjust the pressure at the drilling rig end. Use the drilling rig to drill to the preset position at the hole location of the hydraulic slot drilling. Remove the drill bit and drill rod, and at the same time seal the holes in the fracturing area with cement slurry, leaving the flexible support bracket and support pipe in the borehole.

[0045] i. Adjust the one-way valve deployment device. According to the fracturing drilling position, adjust the one-way valve to open and change the deployment position of the flexible support in sequence.

[0046] j. After the drill rod is withdrawn, the water injection support pipe is connected to the hydraulic pump, and hydraulic pressure is applied to the hole protection bracket to make the flexible bracket I unfold in the slot and fit around the slot.

[0047] k. When the drill bit retreats to the next cutting position, control the stop valve to allow water to enter the hole through the high-pressure water pipe and the drill rod. First, transport water into the hole for a period of time to remove the residue in the hole. After the drilling water returns to normal, cut the seam.

[0048] 1. After the cutting is completed, stop the pressure immediately, turn off the water pump, close the pressure relief valve, remove the hydraulic cutting shallow spiral integral drill pipe and stack it neatly, and keep the high and low pressure conversion cutter, diamond composite drill bit, and ultra-high pressure rotary water tail properly.

[0049] m. Connect the fracturing string to the hydraulic fracturing pump group (hydraulic fracturing pressure control device) through the high-pressure pipeline conversion joint, start the hydraulic fracturing pump group, open the water tank to allow high-pressure water to reach the fracturing channel through the high-pressure pipeline, and start hydraulic fracturing of the slit borehole.

[0050] n. After all the fracturing is completed, stop the pressure immediately and shut down the water pump, take over the gas extraction, and record the gas extraction concentration and pure amount in time.

[0051] o. After the extraction meets the standards, open the one-way valve from the outlet section, start to unload the pressure section by section according to the fracturing drilling hole and the cutting position, and recover the water injection support pipe and the shrunk flexible support I.

[0052] Embodiment 4:

[0053] The main structure of this embodiment is the same as that of embodiment 1, wherein, according to the location of the gas-enriched zone, the gas-enriched zone of this embodiment is distributed on one side of the borehole and is far away from the borehole. When the permeability enhancement effect of a single slit process is insufficient, a split-hole cutting-pressure combined permeability enhancement mode is adopted, slit drilling holes are arranged on one side of the gas-enriched zone, and fracturing drilling holes are constructed on the other side. The slits weaken the coal body and guide the fracturing fissures to develop in a directional manner toward the gas-enriched zone. In view of the problem that the slit grooves of the broken soft coal seams are unstable and the fracturing boreholes are prone to collapse, a flexible hole-groove protection system is designed to protect the grooves and extraction boreholes formed by hydraulic measures to ensure smooth gas extraction after permeability enhancement.

[0054] a. After the drilling rig, pump box, connecting pipelines, etc. are transported to the construction site, they are installed and firmly supported, the pipelines are connected, the emulsion pump is laid, the high-pressure pipeline is laid, and the high-pressure pipeline is debugged. After the equipment installation and connection preparation work is completed, the inspection of related systems is completed.

[0055] b. According to the anti-blowout design of the working face, construction and extraction drilling are carried out according to the preset fracturing drilling and slit drilling positions.

[0056] c. Connect the diamond composite drill bit and the hydraulic slit shallow spiral drill rod in sequence, install the hydraulic slit nozzle equipped with a nozzle on the front end of the high-pressure water jet drill rod, push the drill bit in, then connect the drill rod and the drill bit, push it into the drilling rig, turn on the drilling rig to make the drill rod rotate at a low speed, and use low-pressure water to drill the hole.

[0057] d. After the drill bit reaches the designed position, turn on the high-pressure water pump, and water enters the drill pipe through the ultra-high-pressure hose. Control the stop valve, adjust the pressure at the drilling rig end, and adjust the pressure valve to gradually increase the pressure of the jet system. After the pressure stabilizes, use the high-pressure water jet on the high-pressure nozzle to perform rotary cutting on the coal body on the borehole wall. The rotary cutting time for each cut is 20-25 minutes.

[0058] e. After the seam groove is formed, the drill bit and drill rod continue to retreat, expand the front section fixing device of the bracket, and leave the flexible support bracket and support tube in the borehole.

[0059] f. Control the stop valve to allow water to return to the water tank through the high-pressure water pipe and remove the drill rod at that location.

[0060] g. After the drill rod is withdrawn, the withdrawn drill rod is disassembled, the water-injection support pipe is connected to the hydraulic pump, and hydraulic pressure is applied to the hole protection bracket. The traction device is turned on, the traction device where the slot is located is triggered, and the flexible bracket I is converged at the slot position through the movement of the slide rail.

[0061] h. Connect the water injection support pipe to the hydraulic pump and apply hydraulic pressure to the hole protection bracket to unfold the flexible bracket I and fit around the seam groove.

[0062] i. When the drill bit retreats to the next cutting position, control the stop valve to allow water to enter the hole through the high-pressure water pipe and the drill rod. First, water is transported into the hole for a period of time to remove the residue in the hole. After the drilling water returns to normal, the cutting can be carried out.

[0063] j. After the cutting is completed, stop the pressure immediately and turn off the water pump, close the pressure relief valve, remove the hydraulic cutting shallow spiral integral drill pipe and stack it neatly, and properly store the high and low pressure conversion cutter, diamond composite drill bit, and ultra-high pressure rotary water tail.

[0064] k. Construct fracturing drilling holes at appropriate locations on the other side of the gas-enriched zone.

[0065] 1. Adjust the pressure at the drilling rig end. Drill the hydraulic slotted hole to the preset position with the drilling rig, withdraw the drill bit and drill rod, and seal the fracturing area with cement slurry at the same time, leaving the flexible support bracket and support pipe in the borehole.

[0066] m. Adjust the one-way valve deployment device. According to the fracturing drilling position, adjust the one-way valve to open and change the deployment position of the flexible support in sequence.

[0067] n. Connect the high-pressure pipeline conversion joint of the fracturing string to the hydraulic fracturing pump group (hydraulic fracturing pressure control device), start the hydraulic fracturing pump group, open the water tank to allow high-pressure water to reach the fracturing channel through the high-pressure pipeline, and start hydraulic fracturing of the slit borehole.

[0068] o. After all the fracturing is completed, stop the pressure immediately and shut down the water pump, take over the gas extraction, and record the gas extraction concentration and pure amount in time.

[0069] p. After the extraction meets the standards, open the one-way valve from the outlet section, start to unload the pressure section by section according to the fracturing drilling hole and the cutting position, and recover the water injection support pipe and the shrunk flexible support I.

Claims

1. A hole protection system for coal seam cutting, compression and combined extraction, characterized in that: It includes hydraulic slotting subsystem, hydraulic fracturing subsystem and flexible hole protection system; The hydraulic cutting subsystem includes an ultra-high pressure water jet generation system, a drill pipe and drilling tool system, a hole sealer, a gas-slag separator and a drilling rig; The ultra-high pressure water jet generation system includes an emulsification pump station and a water tank; the drill rod and drill tool system includes a drill rod, a drill bit and a high-pressure water braid; the drill rod is a hollow round tube as a whole; the drill bit is provided with a radial nozzle and an axial nozzle for high-pressure water jetting; the radial nozzle is arranged at the front end of the drill bit; the axial nozzle is arranged on the side wall of the drill bit; the drill bit is installed at the head end of the drill rod; the inner cavity of the drill bit is connected to the inner cavity of the drill rod; the input end of the high-pressure water braid is connected to the emulsification pump station through a high-pressure pipeline, and the output end is connected to the tail end of the drill rod; The orifice sealer is a tubular body; the front end of the orifice sealer is open and fixed on the wall of the borehole, and the rear end is connected to the gas-slag separator; the drill rod extends into the borehole from the rear end of the orifice sealer; the gas-slag separator is connected to the gas extraction pipeline; The hydraulic fracturing subsystem includes an emulsification pump station, a water tank, a sealing device, a fracturing string and a casing; the water tank and the emulsification pump station are connected by a high-pressure hose; after the high-pressure water is generated, it enters the water volume regulating device through a high-pressure water pipe; a flow meter and a pressure gauge are provided on the high-pressure water pipe; the front section of the fracturing string is connected to a high-pressure pipeline conversion joint; The flexible hole protection system comprises a front-end fixing device, a water injection support pipe and a flexible support I (1); a water injection hole is arranged on the wall of the water injection support pipe; the front-end fixing device is connected and fixed to the head end of the water injection support pipe, and the tail end is connected to the hydraulic pump; the front-end fixing device has a supporting claw; the supporting claw adopts a compression spring structure; the water injection support pipe is arranged in the inner cavity of the drill rod; the front-end fixing device is arranged in the central hole of the drill bit; the supporting claw of the front-end fixing device is engaged with the inner wall of the central hole; The flexible support I (1) is a mesh structure; the flexible support I (1) comprises a plurality of annular support tubes arranged in sequence along the longitudinal direction; each annular support tube comprises a plurality of unit waves, and the unit waves are arranged in sequence along the circumferential direction; two adjacent annular support tubes are distributed in mirror symmetry; two opposite wave peaks of two adjacent annular support tubes are fixedly connected; the inner cavities of two adjacent annular support tubes are connected; the inner cavities of the plurality of annular support tubes form a pipe network structure; In a non-working state, the flexible support I (1) in a compressed state is sleeved on the pipe body of the water injection support pipe; the water injection hole is communicated with the inner cavity of the pipe network of the flexible support I (1).

2. A hole protection system for coal seam cutting, compression and combined extraction according to claim 1, characterized in that: It also includes a flexible support II (2); the flexible support II (2) includes a circular ring tube I (201) and a circular ring tube II (202), and a plurality of annular support tubes arranged between the circular ring tube I (201) and the circular ring tube II (202); each annular support tube includes a plurality of unit waves, and the unit waves are arranged in sequence along the circumferential direction; two adjacent annular support tubes are fixedly connected between two opposite wave peaks; the inner cavity of the flexible support II (2) is connected to the hydraulic pump; when working, the fixed traction device drives the circular ring tube I (201) and the circular ring tube II (202) to approach each other, and the annular support tube is deformed and fits the slot; in a non-working state, the flexible support II (2) in a compressed state is sleeved on the pipe body of the water injection support pipe; the water injection hole is connected to the inner cavity of the flexible support II (2).

3. A hole protection system for coal seam cutting, compression and combined extraction according to claim 2, characterized in that: The flexible bracket I (1) and the flexible bracket II (2) are both made of silicon bronze elastic alloy.

4. An in-situ cutting-pressing combined permeability enhancement and hole protection method according to the system of claim 2, characterized in that: The following steps are involved: a. After the drilling rig, pump box and connecting pipelines are transported to the construction site, they are installed and firmly supported, the pipelines and emulsion pumps are connected, the high-pressure pipelines are laid, and the high-pressure pipelines are debugged; after the equipment installation and connection preparation work is completed, the inspection of related systems is completed; b. According to the anti-burst design of the working face, construction and extraction drilling are carried out according to the preset slot drilling positions; c. Connect the drill bit and the hydraulic slotted shallow spiral drill rod in sequence; push the drilling rig in, turn on the drilling rig to make the drill rod rotate at a low speed, and use low-pressure water to drill the borehole; d. After the drill bit reaches the designed position, turn on the high-pressure water pump, and water enters the drill pipe through the ultra-high-pressure hose. Control the stop valve, adjust the pressure at the drilling rig end, and adjust the pressure valve to gradually increase the pressure of the ultra-high-pressure water jet generation system. After the pressure stabilizes, use the high-pressure water jet on the high-pressure nozzle to perform rotary cutting on the coal body on the borehole wall. The rotary cutting time for each cut is 20-25 minutes. e. After the slot is formed, the drill bit and drill rod continue to move backward, propping up the front fixing device, leaving the flexible support II (2) and the water injection support pipe in the borehole; f. Control the stop valve to allow water to return to the water tank through the high-pressure water pipe and remove the drill rod at that location; g. After the drill rod is withdrawn, the withdrawn drill rod is disassembled, the water injection support pipe is connected to the hydraulic pump, and hydraulic pressure is applied to the flexible support II (2), the traction device is turned on, the traction device where the slot is located is triggered, and the flexible support II (2) is converged around the slot by moving the slide rail; h. Adjust the pressure at the drilling rig end, use the drilling rig to drill to the preset position at the hole position of the hydraulic slot drilling, withdraw the drill bit and drill rod, and simultaneously seal the fracturing area borehole with cement slurry, leaving the flexible support I (1) and the water injection support pipe in the borehole; i. Adjust the one-way valve deployment device, adjust the one-way valve according to the fracturing drilling position, and open and change the deployment position of the flexible support in sequence; j. After the drill pipe is withdrawn, the water injection support pipe is connected to a hydraulic pump and hydraulic pressure is applied to the flexible support I (1) so that the flexible support I (1) is unfolded in the slot and fits around the slot; k. When the drill bit retreats to the next slotting position, control the stop valve to allow water to enter the hole through the high-pressure water pipe and the drill rod. First, water is transported into the hole for a period of time to remove the residue in the hole. After the drilling water returns to normal, the slotting can be carried out; 1. After the cutting is completed, stop the pressure immediately, turn off the water pump, close the pressure relief valve, remove the hydraulic cutting shallow spiral integral drill pipe and stack it neatly, and keep the high and low pressure conversion cutting device, diamond composite drill bit, and ultra-high pressure rotary water tail properly; m. Connect the high-pressure pipeline conversion joint of the fracturing pipe string to the hydraulic fracturing pump group; start the hydraulic fracturing pump group, open the water tank to allow high-pressure water to reach the fracturing channel through the high-pressure pipeline, and start hydraulic fracturing of the slotted borehole; n. After all the fracturing is completed, stop the pressure immediately and turn off the water pump, take over the gas extraction, and record the concentration and pure amount of gas extraction in time; o. After the extraction meets the standards, open the one-way valve from the outlet section, start to unload the pressure section by section according to the fracturing drilling and cutting positions, and recover the water injection support pipe and the shrunk flexible support I.

5. A method for drilling and cutting-pressing combined with permeability enhancement and hole protection according to the system of claim 2, characterized in that: The following steps are involved: a. After the drilling rig, pump box, connecting pipelines, etc. are transported to the construction site, they are installed and firmly supported, the pipelines are connected, the emulsion pump is laid, the high-pressure pipeline is laid, and the high-pressure pipeline is debugged; after the equipment installation and connection preparation work is completed, the inspection of related systems is completed; b. According to the anti-burst design of the working face, construction and extraction drilling are carried out according to the preset fracturing drilling and slot drilling positions; c. Connect the drill bit and the hydraulic slotted shallow spiral drill rod in sequence, push them into the drilling rig, turn on the drilling rig to rotate the drill rod at a low speed, and use low-pressure water to drill the borehole; d. After the drill bit reaches the designed position, turn on the high-pressure water pump, and water enters the drill pipe through the ultra-high-pressure hose. Control the stop valve, adjust the pressure at the drilling rig end, and adjust the pressure valve to gradually increase the pressure of the ultra-high-pressure water jet generation system. After the pressure stabilizes, use the high-pressure water jet on the high-pressure nozzle to perform rotary cutting on the coal body on the borehole wall. The rotary cutting time for each cut is 20-25 minutes. e. After the slot is formed, the drill bit and drill rod continue to move backward, propping up the front fixing device, leaving the flexible support II (2) and the water injection support pipe in the borehole; f. Control the stop valve to allow water to return to the water tank through the high-pressure water pipe and remove the drill rod at that location; g. After the drill rod is withdrawn, the withdrawn drill rod is disassembled, the water injection support pipe is connected to the hydraulic pump, and hydraulic pressure is applied to the flexible support II (2), the traction device is turned on, the traction device at the slot is triggered, and the flexible support II (2) is converged at the slot position by moving the slide rail; h. When the drill bit retreats to the next slotting position, control the stop valve to allow water to enter the hole through the high-pressure water pipe and the drill rod. First, water is transported into the hole for a period of time to remove the residue in the hole. After the water return to the hole is normal, the slot can be cut; i. After the cutting is completed, stop the pressure immediately, turn off the water pump, close the pressure relief valve, remove the hydraulic cutting shallow spiral integral drill pipe and stack it neatly, and keep the high and low pressure conversion cutter, diamond composite drill bit, and ultra-high pressure rotary water tail properly; j. Construct fracturing drilling holes at appropriate locations on the other side of the gas-enriched zone; k. Adjust the pressure at the drilling rig end, use the drilling rig to drill to the preset position at the hole position of the hydraulic slot drilling, withdraw the drill bit and drill rod, and simultaneously seal the fracturing area borehole with cement slurry, leaving the flexible support I (1) and the water injection support pipe in the borehole; 1. Adjust the one-way valve deployment device, adjust the one-way valve according to the position of the fracturing drilling hole, and sequentially open and change the deployment position of the flexible support I (1); m. Connect the high-pressure pipeline conversion joint of the fracturing pipe string to the hydraulic fracturing pump group; start the hydraulic fracturing pump group, open the water tank to allow high-pressure water to reach the fracturing channel through the high-pressure pipeline, and start hydraulic fracturing of the slotted borehole; n. After all the fracturing is completed, stop the pressure immediately and shut down the water pump, take over the gas extraction, and record the gas extraction concentration and pure amount in time; o. After the extraction reaches the target, open the one-way valve from the outlet section, start to relieve the pressure section by section according to the fracturing drilling hole and the slot position, and recover the water injection support pipe and the shrunk flexible support I (1).

Images