Coal seam drilling, punching and protecting integrated device and hole protecting method

Abstract

The invention discloses a coal seam drilling, punching and protecting integrated device and a hole protecting method. A reset spring, a pressing head and a switching sleeve with a necking hole are arranged in a water passing inner cavity, the switching sleeve is arranged in the water passing inner cavity in a clearance fit mode, and a water passing hole is formed in the outer side wall of the switching sleeve; the front end of the pressing head is fixedly connected with a reset spring, and the top end of the reset spring is pressed on the wall of the water passing inner cavity. A central shaft hole is formed in the center of the pressing head, a protruding shaft shoulder is arranged on the outer wall of the pressing head, a hole shoulder matched with the shaft shoulder of the pressing head is formed in the water passing inner cavity for assembling the pressing head, and the shaft shoulder can move front and back in the hole shoulder. When low-pressure water is introduced, the water flow passes through the central through hole and then flows out of the flap valve of the drill bit, so that the effects of cooling and deslagging are achieved; when high-pressure water is introduced, the completely unblocked central through hole provides conditions for lowering the hole-protecting screen pipe, the screen pipe can be directly fed into the central through hole, the traditional intermediate procedure of replacing a hollow drill rod for secondary drilling and lowering the drill rod is omitted, the construction time is greatly shortened, meanwhile, the influence of hole collapse is reduced, and the whole-hole-section hole-protecting effect is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of comprehensive pressure relief and permeability enhancement and high-efficiency extraction of soft coal seams and low-permeability coal seams, and particularly relates to an integrated coal seam drilling, flushing and protection device and a hole protection method. Background Art

[0002] In recent years, as my country's coal mining has gradually extended to deeper areas, disasters, primarily coal and gas outbursts, have become more frequent. Gas, as a key factor restricting efficient coal extraction, poses a significant risk to mine safety. Currently, hydraulic punching technology is a relatively effective measure for gas disaster prevention and control, especially in the management of gas in high-gas, soft, and low-permeability coal seams. The main function of this technology is to use high-pressure water jets to punch out certain channels in the coal body along the working face of the drill hole, thereby increasing the number of macro-cracks, creating effective conditions for increasing the permeability of the coal body and the migration of gas, and further improving the efficiency of coal seam gas extraction. However, since it requires pre-construction of a pilot hole, auxiliary operations take a long time. Furthermore, after drilling, the drill rod usually needs to be replaced to protect the hole. This results in low construction efficiency, a short drilling depth, and inability to achieve large-scale extraction.

[0003] Based on the above-mentioned technical problems, there is no relevant solution yet; therefore, there is an urgent need to find effective solutions to solve the above-mentioned problems.

[0004] In order to improve construction efficiency, many technical solutions focus on improving a single process and combining dual processes, but no effective solution has been proposed to solve the problem of integrated drilling, impacting and protection.

[0005] The invention with announcement number CN114876373A discloses an integrated drilling and punching equipment and method for directional long drilling in coal mines. The key points of its technical solution include a drill rod, one end of the punching water jet is connected to the power output end of the drill rod; the inlet of the punching water jet is connected to a hydraulic punching pump truck; a wireless downhole measuring instrument, one end of whose probe is connected to the other end of the punching water jet for detecting the depth of the drill hole; a bottom hole motor, fixed at the other end of the wireless downhole measuring instrument; and a drill bit, which is connected to the output shaft of the bottom hole motor in a transmission manner, thereby realizing coal seam directional drilling construction and downhole punching operations, reducing auxiliary operation time, reducing drilling construction work volume, and improving extraction efficiency. However, it still cannot achieve large-area extraction.

[0006] The invention with announcement number CN113202452B discloses an integrated drilling, flushing and protection coal seam drilling hydraulic hole making device and hole making method. The key points of its technical solution include a pipe body with a water channel embedded in the side wall of the pipe body; a hole making short section is axially connected to the pipe body; a pressure conversion piston assembly is arranged in the pipe body, and the hole making short section is axially connected to the pressure conversion piston assembly; the water flow drives the pressure conversion piston assembly to move axially to seal the water channel, and the high-pressure water flow formed is used to make a high-pressure water hole at the hole making short section, but its structure is complex. Summary of the Invention

[0007] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and to provide a coal seam drilling, punching and protection integrated device and hole protection method, which can realize the operations of hole forming, punching and hole making and screen pipe hole protection in one construction, thereby improving work efficiency.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: A coal seam drilling, flushing and protection integrated device includes a rod body and an outer joint for connecting a drill bit and an inner joint for connecting a drill rod, respectively, provided at both ends of the rod body. A return spring, a pressure head and a switching sleeve with a necking hole fixed to the pressure head are sequentially provided in a water-passing inner cavity. The switching sleeve is arranged in the water-passing cavity and a water-passing hole is opened on its outer wall; The front end of the pressure head is fixedly connected to the return spring, and the top end of the return spring is pressed against the wall of the water cavity; The pressure head has a central shaft hole at its core and a raised shaft shoulder on its outer wall. The water-passing inner cavity for assembling the pressure head has a hole shoulder that matches the pressure head shaft shoulder, and the shaft shoulder can move back and forth in the hole shoulder. The side wall of the pressure head is also provided with a low-pressure water hole leading to the central axis hole, and the water passing through the water cavity is led to the external joint; The outer diameter of the shaft shoulder is larger than the diameter of the water-passing cavity and smaller than the inner diameter of the hole shoulder; The diameter of the necking hole is smaller than that of the central axis hole and the front end thereof is connected to the central axis hole, while the rear end thereof is provided with a sealing channel with a diameter larger than that of the necking hole. A sealing ball is installed in the sealing channel and seals the necking hole. The sealing pressure of the sealing ball is denoted as M. A gap is set between the outer end surface of the sealing channel and the switching sleeve; A high-pressure nozzle is also provided on the side wall of the rod body near the inner joint; During assembly, the return spring is in a compressed state, and the shoulder of the pressure head is pressed on point B of the rear edge of the hole shoulder. The low-pressure water hole is exposed in the hole shoulder, and the high-pressure nozzle is blocked on the outside of the switching sleeve.

[0009] The rod body comprises a left rod body and a right rod body that can be spliced ​​together, and the outer joint is arranged at the front end of the left rod body, and the inner joint is arranged at the rear end of the right rod body.

[0010] A threaded hole is opened on the rear side of the pressure head, and a threaded tube is inserted into the threaded hole and passes through the switching sleeve to be threadedly connected to the pressure head, and the aperture of the threaded tube is larger than the aperture of the necking hole.

[0011] The high-pressure nozzle is protrudingly arranged in the water-passing inner cavity and is arranged in contact with the switching sleeve.

[0012] The inlet of the high-pressure nozzle is configured in a trumpet shape.

[0013] A sealing ball stopper can be detachably provided at the rear port of the sealing channel.

[0014] The sealing ball stopper is configured as a buckled annular structure and is fixedly arranged at the rear port of the sealing channel.

[0015] The material of the blocking ball is polyoxymethylene.

[0016] The minimum deformation pressure of the return spring is 1 MPa.

[0017] A method for protecting a hole of a coal seam integrated drilling, flushing and protecting device, comprising the following steps: (1) Assemble the integrated device between the drill pipe and the drill bit with a flap door to form a hydraulic punching down-pipe drill pipe for laying the gas extraction pipe; (2) Introduce low-pressure water flow to complete drilling construction at the preset position of the coal seam wall in the coal mine Low-pressure water enters through the inner joint, and the sealing ball seals the central through hole under the action of water pressure. The water flows through the gap between the sealing channel and the switching sleeve and flows to the pressure head through the water hole, pushing the pressure head shoulder forward and compressing the reset spring synchronously. The return spring is compressed forward under the action of low-pressure water, so that the pressure head is between point A and point B. The low-pressure water flows through the low-pressure water hole to the central axis hole and finally reaches the external joint, cooling the drill bit and removing slag during the drilling process; (3) Connect high-pressure water with a pressure lower than the plugging pressure M of the plugging ball to the tail end of the drill pipe to perform hydraulic punching and cavitation construction; High-pressure water pushes the pressure head, and the shoulder of the pressure head presses point A tightly, closing the low-pressure water hole. The pressure head drives the sealing ball and the switching sleeve to move forward as a whole, and the high-pressure nozzle is exposed. High-pressure water is ejected from the high-pressure nozzle to perform hydraulic cavitation. (4) After the hydraulic cavitation is completed, the high-pressure water pressure is increased to not less than the plugging pressure M, and the plugging ball is flushed out of the necking hole into the central axis hole; (5) After lowering the screen tube into the borehole through the center hole of the drill pipe, open the bottom hole fixing device and fix the screen tube in the borehole; (6) Remove the hydraulic punching drill rod and seal the hole to complete the pipe laying process.

[0018] The beneficial effects of the present invention are: (1) The present invention discloses an integrated device for drilling, punching and protecting coal seams and a method for protecting a hole. The device comprises the following steps: a reset spring, a pressure head and a switching sleeve with a necking hole fixed to the pressure head are sequentially arranged in a water-passing cavity. The switching sleeve is arranged in the water-passing cavity and a water hole is opened on its outer wall. The front end of the pressure head is fixed to the reset spring, and the top end of the reset spring is pressed against the wall of the water-passing cavity. The center of the pressure head is provided with a central axial hole and a raised shaft shoulder is provided on its outer wall. The water-passing cavity where the pressure head is assembled is provided with a hole shoulder that matches the pressure head shaft shoulder, and the shaft shoulder can be adjusted on the hole shoulder. When low-pressure water is introduced, the water flows through the center through hole and out from the flap door of the drill bit, which plays a role in cooling and removing slag. At the same time, when high-pressure water is introduced, the completely unblocked center through hole provides conditions for the lowering of the hole protection screen pipe, which can be directly sent into the center through hole to complete the lowering of the screen pipe, eliminating the traditional intermediate process of replacing the hollow drill rod and drilling the drill rod for the second time, greatly reducing the construction time, improving the construction efficiency, and also reducing the impact of the hole collapse. It will also increase the hole protection length to achieve the hole protection effect of the entire hole section.

[0019] (2) It can directly cooperate with the drill pipe. The high-pressure nozzle installed on the pipe body can cooperate with the drill pipe to punch holes in water at deep depths, increase the permeability of the coal seam, promote the release of coal seam gas deep in the borehole, and reduce the risk of borehole collapse and clogging. It can increase the length of the lower pipe and achieve the effect of protecting the entire hole section.

[0020] (3) It can directly cooperate with the drill pipe, and the matching sealing ball can realize low-pressure drilling, high-pressure jet hole making and the switching of the pipe-lowering state with the central through hole unobstructed, only by the change of the water pressure. This device can achieve the operations of hole making, punching hole making and screen pipe hole protection in one construction, eliminating the traditional intermediate process of pulling out the drill pipe and drilling the screen pipe for the second time, greatly shortening the construction time and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a schematic diagram of the low-pressure water flow path; Figure 3 It is a schematic diagram of the water flow path in the high-pressure water hydraulic punching mode; Figure 4 This is a schematic diagram of the high-pressure water sealing ball rushing out; Figure 5 It is a schematic diagram of the hydraulic cavitation mode; Figure 6 This is a schematic diagram of the screen pipe without drilling. DETAILED DESCRIPTION

[0022] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0023] See also Figure 1 . It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0024] The present invention provides a coal seam drilling and punching protection integrated device and hole protection method, such as Figures 1 to 6 shown.

[0025] A coal seam drilling, flushing and protection integrated device includes a rod body 5 and an external joint 1 for connecting a drill bit and an internal joint 1-1 for connecting a drill pipe, respectively, provided at both ends of the rod body 5, and a reset spring 2, a pressure head 3 and a switching sleeve 7 with a necking hole 9 fixed to the pressure head 3 are sequentially provided in a water-passing inner cavity. The switching sleeve 7 is gap-arranged in the water-passing inner cavity and a water hole 72 is provided on its outer wall; the front end of the pressure head is fixedly connected to the reset spring 2, and the top end of the reset spring 2 is press-fitted to the wall of the water-passing inner cavity.

[0026] The pressure head 4 has a central axial hole at its center and a raised shaft shoulder on its outer wall. The water-passing inner cavity for assembling the pressure head has a hole shoulder that matches the pressure head shaft shoulder, and the shaft shoulder can move back and forth in the hole shoulder. The side wall of the pressure head 4 is also provided with a low-pressure water hole 3 leading to the central axis hole, and the water passing through the water cavity is led to the external joint 1; and the outer diameter of the shaft shoulder is larger than the hole diameter of the water cavity and smaller than the inner diameter of the hole shoulder.

[0027] The aperture of the necking hole 9 is smaller than that of the central axis hole and its front end is connected to the central axis hole, while its rear end is also provided with a sealing channel 71 with an aperture larger than that of the necking hole, and a sealing ball 6 is installed in the sealing channel and seals the necking hole. The sealing pressure of the sealing ball is recorded as M; when low-pressure water less than the sealing pressure M is fed in, the sealing ball 6 seals the necking hole 9 under the action of water pressure, allowing water to flow through the drill bit; when high-pressure water is used but lower than the sealing pressure, the water is ejected through the high-pressure nozzle 8; and when the high-pressure water pressure reaches the sealing pressure M, the sealing ball 6 is flushed out through the necking hole 9.

[0028] A gap is set between the outer end surface of the sealing channel and the switching sleeve; a high-pressure nozzle 8 is also provided on the side wall of the rod body near the inner joint; in this embodiment, the high-pressure nozzle 8 is protruded in the water-passing inner cavity and is arranged in contact with the switching sleeve, and the inlet of the high-pressure nozzle is set in a trumpet shape.

[0029] During assembly, the return spring is in a compressed state, and the shoulder of the pressure head is pressed on point B of the rear edge of the hole shoulder. The low-pressure water hole is exposed in the hole shoulder, and the high-pressure nozzle is blocked on the outside of the switching sleeve.

[0030] The rod body comprises a left rod body and a right rod body that can be spliced ​​together, and the outer joint is arranged at the front end of the left rod body, and the inner joint is arranged at the rear end of the right rod body.

[0031] In this embodiment, in order to facilitate installation and disassembly, a threaded hole is opened on the rear side of the pressure head, and a threaded tube is inserted into the threaded hole and passed through the switching sleeve to be threadedly connected to the pressure head, and the aperture of the threaded tube is larger than the aperture of the necking hole. During installation, the front end of the threaded tube is screwed into the threaded hole of the pressure head, and then the switching sleeve is screwed into the rear end of the threaded tube and directly reaches the necking hole, thereby realizing the assembly of the pressure head and the switching sleeve.

[0032] The sealing ball stopper 10 can be detachably provided at the rear end of the sealing channel. The sealing ball stopper 10 can be provided as a ring structure that is fastened and fixed at the rear end of the sealing channel.

[0033] The material of the blocking ball 6 is polyoxymethylene, namely POM.

[0034] The minimum deformation pressure of the return spring 2 is 1 MPa, and the elastic limit pressure is 3 MPa, which ensures that the pressure head will not block the low-pressure water hole under low-pressure water conditions.

[0035] When the water pressure entering the inner joint 1-1 is lower than the blocking pressure M and lower than the limit pressure of the return spring 2, it is recorded as low-pressure water; When the water pressure flowing into the inner joint 1 - 1 is higher than the limit pressure of the return spring 2 , it is recorded as high-pressure water.

[0036] When low-pressure water is introduced, the sealing ball 6 seals the neck hole 9 under the action of water pressure, and the switching sleeve 7 blocks the outside of the high-pressure nozzle 8. Water flows through the gap between the sealing channel 71 and the switching sleeve 8 and flows to the pressure head 4 through the water hole, pushing the pressure head shoulder forward and synchronously compressing the reset spring. The pressure head shoulder is located between the hole shoulders. Low-pressure water passes through the low-pressure water hole to the central axis hole and finally reaches the external joint, cooling the drill bit and discharging slag during the drilling process.

[0037] When high-pressure water is introduced and the high-pressure water pressure is lower than the sealing pressure M of the sealing ball, the sealing ball still seals the necked hole under the action of water pressure, and the high-pressure water flows through the gap between the sealing channel and the switching sleeve and flows to the pressure head through the water hole, and pushes the pressure head shoulder to move forward and press on the front edge A of the hole shoulder. The pressure head moves forward and the low-pressure water hole on it is closed. The pressure head synchronously drives the switching sleeve and the sealing ball to move forward as a whole. At this time, the high-pressure nozzle is exposed, and high-pressure water is sprayed from the high-pressure nozzle to perform hydraulic cavitation.

[0038] After the hydraulic cavitation is completed, the high-pressure water pressure is increased to not less than the plugging pressure M, and the plugging ball is flushed out of the necking hole into the central axis hole.

[0039] The hole protection method of the coal seam drilling, punching and protection integrated device involves drilling, punching and pipe lowering, and specifically includes the following steps: (1) Assemble the integrated device between the drill pipe and the drill bit with a flap door to form a hydraulic punching down-pipe drill pipe for laying the gas extraction pipe; (2) Use low-pressure water flow to complete drilling construction at the preset location of the coal seam wall in the coal mine Low-pressure water enters through the inner joint. At this time, the sealing ball seals the central through hole under the action of water pressure. Water flows through the gap between the sealing channel and the switching sleeve and flows to the pressure head through the water hole. The return spring is compressed forward under the action of low-pressure water, so that the pressure head is between points A and B, allowing the low-pressure water to reach the outer joint to achieve the effect of cooling the drill bit and removing slag during the drilling process. (3) Connect high-pressure water to the tail end of the hydraulic punching drill pipe to complete the hydraulic punching hole construction During this process, high-pressure water pushes the pressure head, causing the pressure head's shoulder to compress point A. The low-pressure water through-hole closes, and the pressure head drives the sealing ball and switching sleeve forward as a whole. At this time, the high-pressure nozzle is exposed, and high-pressure water is ejected from the high-pressure nozzle to perform hydraulic cavitation. In this state, the high-pressure water pressure is less than the fixed pressure M of the sealing ball, and the sealing ball still seals the central through-hole. (4) Increase the high-pressure water pressure to no less than the critical pressure M to flush the sealing ball out of the drill pipe; (5) The gas extraction pipe is lowered into the borehole through the central through hole of the hydraulic punching drill pipe and then fixed. In order to prevent the drill pipe from being pulled out when the drill is withdrawn, a bottom hole fixing device is used. When the front end of the bottom hole fixing device pushes the core of the integrated drilling and punching protection device into the coal hole, the two side wings on the bottom hole fixing device at the front end of the hole protection screen are automatically opened by the spring. When the whole set of screens slides toward the hole mouth, they are wedged into the hole wall and fixed upside down at the bottom of the borehole to ensure that the drill tool can be smoothly pulled out of the borehole and the entire hole protection screen remains in the hole. (6) Remove the hydraulic punching drill rod, seal the hole, and complete the pipe laying process.

[0040] In step (4), the critical pressure M of the blocking ball is 11 MPa; the material of the blocking ball is polyoxymethylene, namely POM.

[0041] The minimum deformation pressure of the return spring is 1Mpa, and the elastic limit pressure is 3Mpa, ensuring that the pressure head will not block the low-pressure water through hole under low-pressure water conditions.

[0042] In step (3), the water pressure in the hydraulic cavitation mode is 10 MPa and the time is 5-8 hours.

[0043] It should be noted that the sealing ball is a disposable consumable and needs to be reinstalled after use. At this time, the device needs to be removed, and the sealing ball needs to be pushed into the center through hole. A certain force should be applied to block and jam the necking hole to prevent the ball from being excessively displaced during transportation.

[0044] The following is described in conjunction with detailed embodiments: As shown in the figure, the drilling and hydraulic punching drilling tools include a rod body with a necked hole 9, and an inner joint 1-1 and an outer joint 1 for connecting the drill bit and the drill rod are respectively provided at both ends of the rod body. The switching sleeve 7 is sealed and movably connected to the inner wall of the inner joint 1, and a high-pressure nozzle 8 connected to the water-passing cavity is provided on the side wall of the inner joint 1-1; the piston includes a reset spring 2 and a pressure head 4, the reset spring 2 is limited and fixed in the water-passing cavity of the outer joint, the pressure head 4 is a hollow shaft with a raised shoulder in the middle of its outer wall, and the front end is connected to one end of the reset spring 2, and a hole shoulder is provided in the water-passing cavity of the outer joint 1 to cooperate with the shoulder of the pressure head 4.

[0045] The pressure head 4 is connected to the necking hole 9 whose aperture is smaller than the central through hole; there is a sealing ball 6 outside the necking hole that will undergo elastic deformation under pressure M. The sealing pressure M is a specific pressure value, and its size is determined according to the material of the sealing ball 6. Under normal circumstances, the sealing ball 6 can be made of a material with a certain elastic deformation ability. The diameter of the sealing ball 6 is smaller than the inner diameter of the central through hole and larger than the inner diameter of the necking hole 9. The sealing ball 6 is against the end side of the necking hole 9, so that when low-pressure water less than the sealing pressure M is fed in, the sealing ball 6 seals the necking hole 9 under the action of water pressure, allowing water to flow through the drill bit; when high-pressure water is used but lower than the sealing pressure M, the water is ejected through the high-pressure nozzle, and when the high-pressure water pressure reaches the sealing pressure M, the sealing ball 6 is flushed out through the necking hole 9.

[0046] From the technical solution of the above device, it can be seen that the core actions of this device are three, all of which are completed according to the pressure changes of low-pressure water and high-pressure water: Specifically, when using low-pressure water, the flow path of the water flow is as follows Figure 2As shown, low-pressure water enters through the inner connector 1-1. The sealing ball 6 seals the central through-hole under the action of the water pressure. Water flows through the water holes in the switching sleeve 7 and flows through the low-pressure water hole 3 to the return spring 2. The return spring 2 is compressed forward by the low-pressure water, causing the pressure head to be between points A and B. The low-pressure water can then reach the outer connector 1 through the low-pressure water hole, cooling the drill bit 11 and removing slag during the drilling process.

[0047] After the hole is drilled to the designated position, high-pressure water is switched to the flow path of the water. Figure 3 As shown in the figure, the high-pressure water pressure is lower than the sealing pressure M of the sealing ball. The high-pressure water pushes the pressure head 4, causing the pressure head's shoulder to press against point A, closing the low-pressure water hole. The pressure head then drives the sealing ball 6 and the switching sleeve 7 forward as a whole. The high-pressure nozzle 8 is exposed as the switching sleeve 7 moves, allowing high-pressure water to be ejected from the high-pressure nozzle 8, creating a hydraulic cavitation hole. In this state, the high-pressure water pressure is lower than the sealing pressure M of the sealing ball, and the sealing ball still seals the central through hole.

[0048] After the hydraulic cavitation is completed, the water pressure is further increased, and the water flow path is as follows Figure 4 As shown. At this time, when the water pressure of the high-pressure water reaches or exceeds the elastic deformation pressure of the sealing ball 6, that is, the sealing pressure M, the sealing ball 6 undergoes elastic deformation under the impact of the water pressure. The sealing ball 6 further enters the necked hole 9 under the impact of the hydraulic pressure and is further flushed out of the central through hole. At this time, the central through hole is in a completely through state. At this time, the water flows through the central through hole and flows out from the flap of the drill bit 11, which plays a role in cooling and removing slag. At the same time, the completely unobstructed central through hole provides conditions for the lowering of the hole protection screen. In this state, the screen can be directly sent into the central through hole to complete the lowering of the screen, eliminating the traditional intermediate process of replacing the hollow drill rod and drilling the drill rod twice. This greatly reduces construction time and improves construction efficiency. It also reduces the impact of hole collapse and increases the hole protection length to achieve a full hole protection effect.

[0049] Based on the above device, a process for lowering the hole screen of the integrated coal seam drilling, flushing and protection device includes the following steps: (1) Assemble the above-mentioned coal seam drilling, flushing and protection integrated device between the drill rod 13 and the drill bit 11 with a flap door to form a hydraulic punching lowering drill rod for lowering the gas extraction pipe; (2) Use low-pressure water flow to complete drilling construction at the preset location; Among them, the working water pressure during drilling construction is 2Mpa; (3) Connect high-pressure water to the tail end of the hydraulic punching drill pipe to complete the hydraulic punching hole construction; Among them, the working water pressure in the hydraulic punching mode is 10Mpa, and the time is 5-8h; (4) Increase the high-pressure water pressure to no less than the critical pressure M, and flush the sealing ball 6 out of the hydraulic punching drill pipe; The critical pressure M at which the blocking ball 6 deforms is 11 MPa; the material of the blocking ball 6 is polyoxymethylene, or POM. (5) After the screen tube is lowered into the borehole through the central through hole of the hydraulic punching drill pipe, the bottom hole fixing device 14 is opened to fix the screen tube 15 in the borehole; (6) Remove the hydraulic punching drill rod and seal the hole to complete the pipe laying process.

[0050] This pipe-laying process is aimed at the coal seam drilling environment in coal mines where soft and low-permeability coal seams are prone to hole collapse and shrinkage problems. The holes drilled under these environmental conditions are affected by stress inside the holes, and are prone to hole collapse and shrinkage, which in turn results in a low hole forming rate and a shallow depth below the screen pipe, affecting the smooth progress of gas extraction. Therefore, for this type of coal seam drilling environment, construction requires the use of an integrated device; the pipe-laying process disclosed by this device is also constructed on this basis, and can specifically solve the aforementioned background technical problems that are commonly found in the current existing technology.

[0051] If the terms "first" and "second" are used in this patent to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of describing the present invention and simplifying the description, and the above terms have no special meaning.

[0052] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications are possible without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the claimed invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0053] In the description of the present invention, it should be understood that the terms "front", "rear", "left", "right", "center", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the protection content of the present invention.

Claims

1. A coal seam drilling, flushing and protection integrated device, characterized in that: It includes a rod body and an outer joint for connecting a drill bit and an inner joint for connecting a drill rod at both ends of the rod body, and a reset spring, a pressure head and a switching sleeve with a necking hole fixed to the pressure head are arranged in sequence in the water-passing inner cavity. The switching sleeve is arranged in the water-passing inner cavity and a water-passing hole is opened on its outer wall; The front end of the pressure head is fixedly connected to the return spring, and the top end of the return spring is pressed against the wall of the water-passing inner cavity; The center of the pressure head is provided with a central shaft hole and a raised shaft shoulder is provided on its outer wall. The water-passing inner cavity for assembling the pressure head is provided with a hole shoulder that matches the pressure head shaft shoulder, and the shaft shoulder can move forward and backward in the hole shoulder. The side wall of the pressure head is also provided with a low-pressure water hole leading to the central axis hole, and the water passing through the water-passing inner cavity is passed to the external joint; The outer diameter of the shaft shoulder is larger than the hole diameter of the water-passing inner cavity and smaller than the inner diameter of the hole shoulder; The diameter of the necking hole is smaller than that of the central axis hole and the front end thereof is connected with the central axis hole, while the rear end thereof is provided with a sealing channel with a diameter larger than that of the necking hole, and a sealing ball is installed in the sealing channel and seals the necking hole, and the sealing pressure of the sealing ball is recorded as M; The outer end surface of the sealing channel and the switching sleeve are provided with a gap; A high-pressure nozzle is also provided on the side wall of the rod body near the inner joint; During assembly, the return spring is in a compressed state, and the axial shoulder of the pressure head is pressed on point B of the rear edge of the hole shoulder. The low-pressure water hole is exposed in the hole shoulder, and the high-pressure nozzle is blocked on the outside of the switching sleeve.

2. The coal seam drilling, flushing and protection integrated device according to claim 1, characterized in that: The rod body comprises a left rod body and a right rod body which can be spliced ​​together, and the outer joint is arranged at the front end of the left rod body, and the inner joint is arranged at the rear end of the right rod body.

3. The coal seam drilling, flushing and protection integrated device according to claim 1, characterized in that: A threaded hole is opened on the rear side of the pressure head, and a threaded tube is inserted into the threaded hole and passes through the switching sleeve to be threadedly connected with the pressure head, and the aperture of the threaded tube is larger than the aperture of the necking hole.

4. The coal seam drilling, flushing and protection integrated device according to claim 1, characterized in that: The high-pressure nozzle is convexly arranged in the water-passing inner cavity and is arranged in close contact with the switching sleeve.

5. The coal seam drilling, flushing and protection integrated device according to claim 4, characterized in that: The inlet of the high-pressure nozzle is configured to be trumpet-shaped.

6. The coal seam drilling, flushing and protection integrated device according to claim 1, characterized in that: A sealing ball stopper can be detachably provided at the rear port of the sealing channel.

7. The coal seam drilling, flushing and protection integrated device according to claim 6, characterized in that: The blocking ball stopper is configured as a buckled annular structure and is fixedly arranged at the rear port of the sealing channel.

8. The coal seam drilling, flushing and protection integrated device according to claim 1, characterized in that: The material of the blocking ball is polyoxymethylene.

9. The coal seam drilling, flushing and protection integrated device according to claim 1, characterized in that: The minimum deformation pressure of the return spring is 1 MPa.

10. A hole protection method for a coal seam drilling, punching and protection integrated device according to any one of claims 1 to 9, comprising the following steps: (1) Assemble the integrated device between the drill pipe and the drill bit with a flap door to form a hydraulic punching down-pipe drill pipe for laying a gas extraction pipe; (2) Introduce low-pressure water flow to complete drilling construction at the preset position of the coal seam wall in the coal mine Low-pressure water enters through the inner joint, and the sealing ball seals the central through hole under the action of water pressure. Water flows through the gap between the sealing channel and the switching sleeve and flows to the pressure head through the water hole, pushing the pressure head shoulder forward and compressing the reset spring synchronously. The return spring is compressed forward under the action of low-pressure water, so that the pressure head is between point A and point B. The low-pressure water flows through the low-pressure water hole to the central axis hole and finally reaches the external joint, cooling the drill bit and removing slag during the drilling process; (3) Connect high-pressure water with a pressure lower than the plugging pressure M of the plugging ball to the tail end of the drill pipe to perform hydraulic punching and hole making construction; High-pressure water pushes the pressure head, and the pressure head's shoulder presses point A, closing the low-pressure water hole. The pressure head drives the sealing ball and the switching sleeve to move forward as a whole, and the high-pressure nozzle is exposed. High-pressure water is sprayed out from the high-pressure nozzle to perform hydraulic cavitation. (4) After the hydraulic cavitation is completed, the high-pressure water pressure is increased to not less than the plugging pressure M, and the plugging ball is flushed out of the neck hole into the central axis hole; (5) After lowering the screen tube into the borehole through the central through hole of the drill pipe, open the bottom hole fixing device to fix the screen tube in the borehole; (6) Remove the hydraulic punching drill rod and seal the hole to complete the pipe laying process.

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