A drilling and punching integrated coal seam drilling hydraulic cavitation device, system and method

Abstract

This invention discloses an integrated drilling, flushing, and protection device, system, and method for hydraulic cavity creation in coal seam drilling. The device comprises a pipe body, within which a first spring and a pressure conversion piston are sequentially mounted axially. A cavity-creating section extends into the pipe body at one end and is axially connected to the pressure conversion piston. Water channels are embedded in the pipe wall. Part of the water flow from the cavity-creating section is ejected from its side to form a cavity-creating water flow; another part flows along the gap between the pipe body and the cavity-creating section and is transmitted through the water channels to the other end of the pipe body to flush the borehole. As the water pressure increases, the pressure conversion piston is axially displaced to block the water channels, increasing the pressure of the cavity-creating water flow. This invention solves the problem of installing a screen pipe inside the hydraulic cavity-creating drill bit, achieving integrated drilling, hydraulic cavity creation, and screen pipe protection, avoiding the difficulties in borehole protection and low efficiency in gas and coalbed methane extraction caused by borehole collapse after drilling.

Description

Technical Field

[0001] This invention relates to engineering fields such as borehole protection technology for underground gas extraction in coal mines, coal and gas control, and coalbed methane development, specifically to a hydraulic cavity-making device, system, and method for integrated drilling, flushing, and protection in coal seams. Background Technology

[0002] Coal seams in my country generally exhibit the characteristics of "three lows and one high," namely, low saturation, low permeability, low reservoir pressure, and high metamorphism. Under these conditions, coalbed methane development and gas control are becoming increasingly problematic, especially in soft, fractured coal seams in mines (wells) lacking protective layer mining conditions. Adopting permeability enhancement measures to assist gas drainage is currently the most widely used and effective gas control method. Hydraulic perforation technology uses high-pressure water jets to impact and break up the coal body within a borehole, expelling large amounts of coal and gas. This creates large-diameter cavities within the coal seam. Under stress, the existing fractures in the surrounding coal body expand, and new fractures are generated, achieving pressure relief, permeability enhancement, and improved drainage. It has significant advantages such as simple construction and operation, high cost-effectiveness, and obvious permeability enhancement effects, making it highly scalable. In recent years, hydraulic perforation technology has undergone extensive testing and application in many coal mining areas in my country, effectively improving coal seam permeability, significantly increasing the effective drainage radius, and shortening the time required for gas drainage to meet standards. Existing hydraulic and mechanical hole-making drills, due to their structural limitations and lack of a hollow internal channel, cannot achieve hole creation by inserting a screen pipe into the borehole from within the drill rod without lifting the drill bit. Furthermore, after lifting the drill bit, the hole-creating section is prone to collapse, making it difficult to insert the screen pipe into the open hole. Currently, open-hole extraction is commonly used after hydraulic perforation drilling, but coal seams are generally fractured and prone to collapse, making it difficult to insert a screen pipe into the open hole for protection and extraction, significantly impacting extraction efficiency. Therefore, there is a real need for an integrated drilling, perforation, and protection hole-making device and drilling process. Summary of the Invention

[0003] The technical problem to be solved by this invention is that after hydraulic perforation drilling in soft, low-permeability coal seams, due to the structural limitations of existing hydraulic and mechanical hole-making drill tools, it is impossible to complete the hole by lowering a screen pipe inside the drill rod without lifting the drill after hole creation, and instead use bare hole extraction, which affects the extraction effect. This invention provides a hydraulic hole-making device, system and method for coal seam drilling that integrates drilling, perforation and protection, so as to achieve efficient extraction and development of gas and coalbed methane in soft, low-permeability coal seams.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0005] A hydraulic cavity-making device for drilling, flushing and protection in coal seams is provided, with a pipe body in which a first spring and a pressure conversion piston are sequentially mounted along the axial direction.

[0006] A cavity-forming short section is provided by extending one end into the tube body and connecting it to the pressure conversion piston shaft;

[0007] Water channels are embedded in the pipe wall of the pipe body. Part of the water flow from the cavity-forming section is sprayed from the side of the cavity-forming section to form a cavity-forming water flow; another part of the water flow flows along the gap formed between the pipe body and the cavity-forming section and is transmitted to the other end of the pipe body through the water channels to flush the borehole.

[0008] As the water pressure increases, the water pressure pushes the pressure conversion piston to move axially to block the waterway and increase the pressure of the water flow that creates the cavity.

[0009] Optionally, the pressure conversion piston is a tubular component, and a water-stopping piston is embedded in the pressure conversion piston near the end of the cavity-forming section; the water-stopping piston is provided with a tubular piston body with one end sealed, and a second spring and a pressure balance body are sequentially installed inside the sealed end. The pressure balance body achieves axial and radial limitation by a limiting body embedded in the inner wall of the piston body; the pressure balance body compresses the second spring to achieve axial displacement, thereby releasing the axial and radial limitation of the limiting body.

[0010] Optionally, the pressure balancer is provided with a flared limiting compression end, the outer diameter of the limiting compression end gradually increases, and a second spring is placed inside the limiting compression end; a drop groove section with a reduced outer diameter is axially connected to the limiting compression end, and a water inlet channel is opened on the side wall of the pressure balancer.

[0011] Optionally, a through-hole is embedded in the inner wall of the piston body, the diameter of which gradually decreases from the inner wall to the outer wall; a limiting body is inserted into the limiting hole, the limiting body being a spherical component.

[0012] Optionally, a second guide ring and a bulletproof gasket are embedded in the piston body behind the pressure balancer.

[0013] Optionally, a piston extension tube is connected to the other end of the pressure conversion piston. The diameter of the piston extension tube is smaller than that of the pressure conversion piston, and multiple water passage holes are drilled on the piston extension tube.

[0014] Optionally, a water channel is formed on the inner wall of the tube, and an inlet hole is provided at the end of the water channel connecting the tube and the gap formed between the tube and the cavity-forming short section. An outlet hole is provided on the tube wall of the sealing section of the pressure conversion piston, and a drain hole is provided at the tail end of the tube.

[0015] Optionally, the diameter of the drain hole is smaller than the diameter of the outlet hole, and the diameter of the outlet hole is smaller than the diameter of the waterway.

[0016] A hydraulic cavity-making system for coal seam drilling integrating drilling, flushing, and protection is provided, which is sequentially connected and arranged with an openable and closable drill bit, a hydraulic cavity-making device, a spiral drill rod, a drilling rig, a water supply, a high-pressure hose, and a high-pressure water pump; the hydraulic cavity-making device is any of the hydraulic cavity-making devices for coal seam drilling integrated drilling, flushing, and protection described in this invention.

[0017] A method for hydraulic cavity creation in coal seam drilling integrating drilling, flushing and protection, which is completed using the hydraulic cavity creation system for coal seam drilling integrated drilling, flushing and protection described in this invention, includes: Step 1: Connecting in sequence an openable and closable drill bit, a hydraulic cavity creation device, a spiral drill rod, a drilling rig, a water channel, a high-pressure hose and a high-pressure water pump to perform non-cavity drilling to form a hole. At this time, the water pump pressure is adjusted to not exceed 3MPa, the openable and closable drill bit rotates to form a hole, and the water flow from the water pump flows through the water channel to the openable and closable drill bit for drill bit cooling and flushing.

[0018] Step 2: Drill into the predetermined cavity-making section, increase the water pump flow and pressure. When the water pump pressure is higher than 3 MPa, the water pressure pushes the pressure conversion piston to block the water channel, causing the pressure to rise step by step. The water flow is concentrated and sprayed through the side of the cavity-making short section to form the cavity-making water flow.

[0019] Step 3: After the cavity is created, gradually reduce the water pump flow rate to lower the pump pressure. The pressure conversion piston is pushed back by the first spring, and most of the water flows through the waterway to the drill bit. In conjunction with the rotation of the drilling rig, the next stage of non-cavity drilling is carried out. When cavity creation is required, repeat step 2.

[0020] Step 4: After all drilling and hole creation are completed, repeatedly flush the hole, open and close the drill bit, and turn off the water pump.

[0021] Step 5: Remove the water pipe, connect the screen pipe impactor, screen pipe suspension device, and screen pipe respectively, and push the screen pipe in from the drill rod. When the screen pipe impactor contacts the water stop piston, continue to apply the thrust to release the water stop piston from its limit. Continue to apply the force to push the water stop piston and screen pipe through the openable drill bit to the bottom of the hole.

[0022] Step 6: After the screen pipe is pushed to the bottom of the hole, the suspension device is opened to hook onto the hole wall, the drill string is lifted out and the screen pipe is left in the hole for sealing and gas extraction.

[0023] The beneficial effects of this invention are:

[0024] (1) It solved the problem of the screen pipe inside the hydraulic hole-making drill bit, and realized the integrated construction of drilling, hydraulic hole-making and screen pipe protection, avoiding the problems of hole protection difficulty and low gas and coalbed methane extraction efficiency caused by hole collapse after drilling.

[0025] (2) The pressure conversion piston can effectively limit and protect the spring, thus improving the life of the cavity-making device;

[0026] (3) The steel ball of the water-stopping piston and the pressure-balanced piston components can effectively ensure the stability of the water pressure in the cavity and the reliability of the cavity-making device, thus broadening the scope of application of the cavity-making device and technology. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is a schematic diagram of the connection of the integrated drilling, flushing, and protection hydraulic cavity-making drilling system of the present invention;

[0029] Figure 2 This is a schematic diagram of the integrated drilling, flushing, and protection coal seam hydraulic cavity-making device of the present invention;

[0030] Figure 3 This is a schematic diagram of the water-stopping piston structure of the present invention;

[0031] The labels in the diagram represent:

[0032] 1-Openable and closable drill bit, 2-Coal seam, 3-Hydraulic cavity-making device, 4-Auger drill rod, 5-Drilling rig, 6-Water supply, 7-High-pressure hose, 8-Pressure gauge, 9-Flow meter, 10-High-pressure water pump;

[0033] 31-Cavity-making short section, 311-Short section female thread, 312-High-pressure nozzle, 313-Short section male thread, 314-Water passage groove;

[0034] 32-pipe body, 321-pipe body female buckle, 322-water inlet hole, 323-water channel, 324-water outlet hole, 325-drain hole, 326-plug, 327-pipe body male buckle;

[0035] 33-Pressure conversion piston, 331-Sealing groove, 332-First guide ring, 333-Water inlet sealing ring, 334-Water outlet sealing ring, 335-Piston extension tube, 336-Water passage hole;

[0036] 34 - First spring;

[0037] 35-Water-stopping piston, 351-Piston body, 3511-Limiting hole, 3512-Sealing ring, 352-Second spring, 353-Pressure balance body, 3531-Limiting compression end, 3532-Water inlet channel, 3533-Return groove section, 354-Limiting body, 355-Second guide ring, 356-Bulletproof gasket. Detailed Implementation

[0038] The implementation methods, principle design, and technical effects of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be used to limit the scope of protection of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0039] Combination Figure 2-3 The integrated drilling, flushing, and protection hydraulic cavity-forming device of the present invention includes a pipe body 32, inside which a first spring 34 and a pressure conversion piston 33 are sequentially mounted axially. A cavity-forming section 31 extends into the pipe body 32 at one end and is axially connected to the pressure conversion piston 33. A water channel 323 is embedded in the pipe wall of the pipe body 32. Part of the water flow from the cavity-forming section 31 is sprayed from the side of the cavity-forming section 31 to form a cavity-forming water flow. Another part of the water flow flows along the gap formed between the pipe body 32 and the cavity-forming section 31 and is transmitted to the other end of the pipe body 32 to flush the borehole. When the water pressure increases, the water pressure pushes the pressure conversion piston 33 to move axially to block the water channel 323, thereby increasing the pressure of the cavity-forming water flow. The short section female thread 311 of the cavity-making short section 31 is used to connect the high-pressure sealing drill rod. The high-pressure nozzle hole provided on the side wall of the cavity-making short section 31 is used to install the high-pressure nozzle 312 for cavity making. The size and type of the nozzle can be changed according to the cavity-making requirements. A water passage 314 is provided on the side wall of the cavity-making short section 31 downstream of the high-pressure nozzle 312. The water passage 314 is used to distribute and guide the water flow to the water channel 323 of the pipe body 32 during cavity making and normal drilling. For example, in a more specific structure, the male connector 313 on the left side of the cavity-making section 31 is connected to the female connector 321 on the right side of the tube body 32; the pressure conversion piston 33 is placed inside the through hole of the tube body 32, and the outer step surface on the left side is connected to one end of the first spring 34, while the other end of the first spring 34 is placed inside the inner step surface on the left side of the tube body 32; the structure provided by this invention solves the problem of the inner screen pipe of the hydraulic cavity-making drill bit, realizes the integrated construction of drilling, hydraulic cavity-making, and screen pipe protection, and avoids the problems of difficult hole protection and low gas and coalbed methane extraction efficiency caused by hole collapse after drilling is lifted.

[0040] In the embodiments of this disclosure, the pressure conversion piston 33 is a tubular component, and a water-stopping piston 35 is embedded in the pressure conversion piston 33 near the end of the cavity-forming section 31. The water-stopping piston 35 has a tubular piston body 351 with one end sealed. Inside the water-stopping piston 35, a second spring 352 and a pressure balancing body 353 are sequentially mounted from the sealed end. The pressure balancing body 353 is axially and radially limited by a limiting body 354 embedded in the inner wall of the piston body 351. The pressure balancing body 353 compresses the second spring 352 to achieve axial displacement, thereby releasing the axial and radial limitations of the limiting body 354. The water-stopping piston 35 is fixed in position inside the pressure conversion piston 33 by its specific structure. While providing axial sealing, it can also be released by external force when the axial seal needs to be removed.

[0041] In the embodiments of this disclosure, the pressure balancer 353 is provided with a flared limiting compression end 3531. The outer diameter of the limiting compression end 3531 gradually increases, mainly to ensure that its outer wall and the limiting body 354 are tightly pressed together at the maximum outer diameter. When the pressure balancer 353 moves axially, the pressing force with the limiting body 354 can be released at the slightly smaller outer diameter, thereby releasing the limiting position. The limiting compression end 3531 is a structure similar to a constricted end, with a cavity inside, used to cover and press the second spring 352. That is, the second spring 352 is pressed into the limiting compression end 3531, and at the same time, it provides axial limiting protection for the spring. A return groove section 3533 with a reduced outer diameter is axially connected to the limiting compression end 3531 to ensure smooth release of the limiting position. A water inlet channel 3532 is opened on the side wall of the pressure balancer 353 to balance the water pressure.

[0042] In the embodiments of this disclosure, a through-hole 3511 is embedded in the inner wall of the piston body 351, the diameter of which gradually decreases from the inner wall to the outer wall. A limiting body 354 is fitted inside the limiting hole 3511. The limiting body 354 is a spherical component, with a smaller outer diameter and a larger inner diameter of the limiting hole 3511. This limits the limiting body 354 and facilitates its retraction, ensuring the limiting function of the limiting body 354 in both the axial and radial directions, while only allowing the limiting body 354 to move inward and slide down. Multiple sealing rings 3512 are embedded in the outer wall of the piston body 351 to seal the gap between the water-stopping piston 35 and the inner wall of the pressure conversion piston 33.

[0043] In the embodiments of this disclosure, a second guide ring 355 and a bulletproof gasket 356 are embedded in the piston body 351 behind the pressure balancer 353. The bulletproof gasket 356 limits the pressure balancer 353; the pressure balancer 353 has an internal through-hole structure. When water enters, water pressure fluctuates, or water pressure suddenly increases during cavity creation, water flow can enter the inner cavity formed by the pressure balancer 353 and the outer tube of the water-stop piston 35 through the water inlet channel 3532 to balance the internal and external pressures and prevent the water-stop piston 35 from displacing. When cavity creation is completed, under the action of external force, the pressure balancer 353 compresses the second spring 352, and the limiting body 354 falls back, thereby driving the water-stop piston 35 to rush out of the hole.

[0044] In the embodiments of this disclosure, a piston extension tube 335 is connected to the other end of the pressure conversion piston 33. The diameter of the piston extension tube 335 is smaller than that of the pressure conversion piston 33, and multiple water passage holes 336 are drilled in the piston extension tube 335. The pressure conversion piston can effectively limit and protect the spring, thereby improving the lifespan of the cavity-forming device. The pressure conversion piston 33 and the sealing groove 331 are used to limit the water-stopping piston 35; the first guide ring 332 provides support and guidance; the inlet sealing ring 333 prevents water from entering the gap; the outlet sealing ring 334 is used to seal the outlet hole 324 when creating a cavity; the piston extension tube 335 guides, limits, and protects the first spring 34, preventing the first spring 34 from shifting when compressed. When the piston extension tube 335 moves to the inner step surface on the left side of the tube body 32, the first spring 34 is not fully compressed and a certain gap is left to prevent the first spring 34 from continuing to compress and becoming fatigued and damaged, thus protecting the first spring 34; the water passage hole 336 is used to guide the water from the outlet hole 324 more smoothly into the piston through-diameter to the drill bit after the first spring 34 is compressed and the piston extension tube 335 moves to the left side of the tube body 32, preventing back pressure from being generated at the outlet.

[0045] In the embodiments of this disclosure, a water channel 323 is formed on the inner wall of the pipe body 32, and an inlet hole 322 is provided at the end of the water channel connecting the pipe body 32 and the cavity-forming section 31. An outlet hole 324 is provided on the pipe wall of the sealing section of the pressure conversion piston 33, and a drain hole 325 is provided at the tail end of the pipe body 32. In addition, the diameter of the drain hole 325 is smaller than the diameter of the outlet hole 324, and the diameter of the outlet hole 324 is smaller than the diameter of the water channel 323. The female thread 321 of the pipe body 32 is connected to the male thread 313 of the short section; the diameter of the inlet of the water inlet 322 is determined according to the required water flow and throttling pressure; multiple channels 323 are arranged around the perimeter, and their diameter is larger than that of the water inlet 322; the diameter of the outlet 324 is smaller than that of the channel 323, and its diameter is determined according to the required water flow during low-pressure drilling; the process holes in the pipe wall are sealed with plugs 326; the function of the drain hole 325 is to release a certain amount of water to the drill bit channel after the outlet hole 324 is sealed during hole creation to prevent the drill bit from being blocked by coal dust; the function of the plug 326 is to seal the process holes on the end face of the channel 323 to form a closed channel; the male thread 327 of the pipe body is connected to the openable and closable drill bit 1. The diameter of the outlet 324 is calculated according to formula (1) and finally determined in combination with experiments.

[0046]

[0047] Where: q is the outflow rate, L / min;

[0048] α — a dimensionless correction coefficient, generally less than 1, which can be determined experimentally;

[0049] p — pressure difference between inlet and outlet, MPa;

[0050] d—— is the diameter of the water outlet, in mm.

[0051] Combination Figure 1 The integrated drilling, flushing, and protection coal seam drilling hydraulic cavity-making system of the present invention is sequentially connected and arranged with an openable and closable drill bit 1, a hydraulic cavity-making device 3, a spiral drill rod 4, a drilling rig 5, a water pump 6, a high-pressure hose 7, and a high-pressure water pump 10; the hydraulic cavity-making device 3 is any one of the integrated drilling, flushing, and protection coal seam drilling hydraulic cavity-making devices given in the present invention.

[0052] The working principle of the integrated drilling, flushing, and protection hydraulic cavity-making device of the present invention:

[0053] The initial state of the cavity-creating device is as follows Figure 2 As shown, water flows into the cavity-making section 31 through the spiral drill rod 4. At this time, part of the water flows out through the high-pressure nozzle 312, while the other part, due to the blockage of the pressure conversion piston 33 and the water-stopping piston 35, can only flow through the water passage 314 through the annular space formed by the cavity-making section 31 and the pipe body 32, and then through the water inlet 322, water channel 323, water outlet 324 and drain hole 325 to the drill bit.

[0054] During non-hole drilling, the drill bit contains low-pressure water (less than 3MPa). Only a small portion of the water flows out through the high-pressure nozzle 312 to prevent the nozzle from being blocked by coal dust and to help remove drill cuttings from the hole. The remaining water pressure acting on the right end face of the pressure conversion piston 33 is too small to push the pressure conversion piston 33 to fully compress the first spring 34 to seal the water outlet 324. Furthermore, the drain hole 325 has a small diameter, and most of the water flows through the water outlet 324, the gap between the first spring 34 and the water passage 336 to the openable drill bit 1. Its function is to cool the openable drill bit 1 and flush out the rock cuttings.

[0055] When hydraulic cavity creation is performed, the water pressure is increased (greater than 3MPa). At this time, the water pressure acts on the pressure conversion piston 33, and the thrust increases. When the piston extension tube 335 moves to the inner step surface on the left side of the tube body 32, the water outlet sealing ring 334 just blocks the water outlet hole 324. Since the total water flow cross section suddenly decreases while the water volume remains unchanged, the water pressure increases rapidly. Most of the water flow is ejected through the high-pressure nozzle 312 to create a jet cavity, and a small portion of the water flow flows to the drill bit through the drain hole 325 to prevent the openable drill bit from being blocked by coal dust.

[0056] After the hole is created, the hole protection screen pipe with impactor is lowered into the hole through the drill rod under the action of external force. When it reaches the water stop piston 35, the pressure balance body 353 compresses the second spring 352, and the limit body 354 falls back to the return groove section 3533. The screen pipe drives the entire water stop piston 35 to rush out of the openable drill bit 1 to protect the hole.

[0057] The integrated drilling, percussion, and protection device for hydraulic cavity creation in coal seams and the process method for cavity creation without lifting the drill screen pipe after percussion include the following:

[0058] Step 1: Connect the openable drill bit 1, hydraulic cavity-making device 3, spiral drill rod 4, drilling rig 5, water pipe 6, high-pressure hose 7 and high-pressure water pump 10 in sequence. The high-pressure water pump 10 is equipped with a pressure gauge 8 and a flow meter 9 to perform non-cavity drilling in the coal seam 2. At this time, adjust the water pump pressure to not exceed 3MPa. The openable drill bit 1 rotates to form a hole. The water flow from the water pump flows to the openable drill bit 1 through water channel 323 for drill bit cooling and hole flushing.

[0059] Step 2: Drill into the predetermined cavity-making section, increase the flow rate and pressure of the high-pressure water pump 10. When the water pump pressure is higher than 3 MPa, the water pressure pushes the pressure conversion piston 33 to block the water outlet 324, causing the pressure to rise stepwise. The water flow is concentrated and flows out through the high-pressure nozzle hole of the cavity-making section 31 to perform high-pressure water jet cavity making.

[0060] Step 3: After the cavity is created, gradually reduce the flow rate of the high-pressure water pump 10 to lower the pump pressure. The pressure conversion piston 33 is pushed back by the first spring 34, and most of the water flows to the drill bit through the water channel 323. In conjunction with the rotation of the drilling rig, the next stage of non-cavity drilling is carried out. When cavity creation is required, the second step is repeated.

[0061] Step 4: After all drilling and hole creation are completed, repeatedly flush the drill bit 1 and shut down the high-pressure water pump 10.

[0062] Step 5: Remove the water pipe 6, connect the screen pipe impactor, screen pipe suspension device and screen pipe respectively, push the screen pipe into the large diameter high pressure sealing drill rod 5, and continue to apply the thrust after the screen pipe impactor contacts the water stop piston 35, which drives the pressure balance body 353 to compress the second spring 352, causing the limit body 354 to fall back into the return groove section 3533, so that the water stop piston 35 is released from the limit hole 3511, and continue to apply force to push the water stop piston 35 and the screen pipe through the openable drill bit 1 to the bottom of the hole;

[0063] Step 6: After the screen pipe is pushed to the bottom of the hole, the suspension device is opened to hook onto the hole wall, the drill string is lifted out and the screen pipe is left in the hole for sealing and gas extraction.

[0064] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0065] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0066] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A hydraulic cavity-making device for coal seam drilling integrating drilling, flushing, and protection, characterized in that, A tube body (32) is provided, and a first spring (34) and a pressure conversion piston (33) are sequentially installed along the axial direction inside the tube body (32). A cavity-forming section (31) is inserted into the pipe body (32) at one end and axially connected to the pressure conversion piston (33). A water channel (323) is embedded in the pipe wall of the pipe body (32). Part of the water flow from the cavity-forming section (31) is sprayed from the side of the cavity-forming section (31) to form a cavity-forming water flow. The other part of the water flow is transmitted through the water channel (323) to the other end of the pipe body (32) to flush the borehole. After the water pressure increases, the water pressure pushes the pressure conversion piston (33) to move axially to block the water channel (323) and increase the pressure of the cavity-forming water flow. The pressure conversion piston (33) is a tubular component, and a water-stopping piston (35) is embedded in the pressure conversion piston (33) near the end of the cavity-making short section (31). The water-stopping piston (35) is provided with a tubular piston body (351) with one end sealed. A second spring (352) and a pressure balance body (353) are sequentially installed from the sealed end. The pressure balance body (353) achieves axial and radial limitation through a limiting body (354) embedded in the inner wall of the piston body (351). The pressure balance body (353) compresses the second spring (352) to achieve axial displacement and release the axial and radial limitation of the limiting body (354). The pressure balancer (353) is provided with a flared limiting compression end (3531), the outer diameter of the outer wall of the limiting compression end (3531) gradually increases, and the second spring (352) is placed inside the limiting compression end (3531); a drop groove section (3533) with a reduced outer diameter is axially connected to the limiting compression end (3531), and a water inlet channel (3532) is opened on the side wall of the pressure balancer (353). A water channel (323) is opened on the inner wall of the pipe body (32), and an inlet hole (322) is provided at the end of the water channel that connects the gap between the pipe body (32) and the cavity-making short section (31). An outlet hole (324) is provided on the pipe wall of the sealing section of the pressure conversion piston (33), and a drain hole (325) is provided at the tail end of the pipe body (32). The diameter of the drain hole (325) is smaller than that of the outlet hole (324), and the diameter of the outlet hole (324) is smaller than that of the water channel (323).

2. The integrated drilling, flushing, and protection coal seam hydraulic cavity-making device according to claim 1, characterized in that, A through-hole (3511) is embedded in the inner wall of the piston body (351), and the diameter of the through-hole (3511) gradually decreases from the inner wall to the outer wall. A limiting body (354) is installed inside the limiting hole (3511), and the limiting body (354) is a spherical component.

3. The integrated drilling, flushing, and support coal seam hydraulic cavity-making device according to claim 1 or 2, characterized in that, A second guide ring (355) and a bulletproof pad (356) are embedded in the piston body (351) behind the pressure balancer (353).

4. The integrated drilling, flushing, and support coal seam hydraulic cavity-making device according to claim 1 or 2, characterized in that, A piston extension tube (335) is connected to the other end of the pressure conversion piston (33). The diameter of the piston extension tube (335) is smaller than that of the pressure conversion piston (33), and multiple water passage holes (336) are drilled on the piston extension tube (335).

5. A hydraulic cavity-making system for coal seam drilling, characterized in that, The following components are connected in sequence: a closable drill bit (1), a hydraulic cavity-making device (3), a spiral drill rod (4), a drilling rig (5), a water pipe (6), a high-pressure hose (7), and a high-pressure water pump (10). The hydraulic cavity-making device (3) is the integrated drilling, flushing, and protection coal seam hydraulic cavity-making device as described in any one of claims 1-4.

6. A hydraulic cavity-creating method for coal seam drilling integrating drilling, flushing, and support, characterized in that, The drilling and flushing integrated coal seam drilling hydraulic hole-making system described in claim 5 is used to complete the following steps: Step 1: Connect the openable and closable drill bit (1), hydraulic hole-making device (3), spiral drill rod (4), drilling machine (5), water pipe (6), high pressure hose (7) and high pressure water pump (10) in sequence to perform non-hole-making drilling. At this time, adjust the pressure of the high pressure water pump (10) to not exceed 3MPa, and the openable and closable drill bit (1) rotates to form a hole. The water flows through the water channel (323) to the openable and closable drill bit (1) for drill bit cooling and flushing. Step 2: Drill into the predetermined cavity section, increase the pressure of the high-pressure water pump (10) to above 3 MPa, and the water pressure pushes the pressure conversion piston (33) to block the water channel (323) so that the pressure rises stepwise and the water flow is concentrated and sprayed through the side of the cavity section (31) to form the cavity water flow; Step 3: After the hole is created, the pressure of the high-pressure water pump (10) is reduced, and the pressure conversion piston (33) is pushed back by the first spring (34). Most of the water flows through the water channel (323) to the drill bit, and the drilling machine rotates to carry out the next stage of non-hole-creating drilling. When hole creation is needed, the second step is repeated. Step 4: After all drilling and hole making are completed, repeatedly flush the drill bit (1) and shut down the high-pressure water pump (10). Step 5: Remove the water pipe (6), connect the screen pipe impactor, screen pipe suspension device and screen pipe respectively, push the screen pipe in from the drill rod, and continue to apply the thrust when the screen pipe impactor contacts the water stop piston (35) to release the water stop piston (35) from the limit, and continue to apply the force to push the water stop piston (35) and screen pipe through the openable drill bit (1) to the bottom of the hole. Step 6: After the screen pipe is pushed to the bottom of the hole, the suspension device is opened to hook onto the hole wall, the drill string is lifted out and the screen pipe is left in the hole for sealing and gas extraction.

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