Low-permeability coal seam layer-by-layer hole enlarging and hole penetration protection drilling tool and drilling method

Abstract

The application discloses a low-permeability coal seam layering reaming, permeability-increasing and hole-protecting drilling tool and a drilling method. The right end of a first guide pipe four-rib grooved drill rod is connected with the left end of a large-diameter drill bit. A through-pipe variable-diameter reamer is arranged between the first guide pipe four-rib grooved drill rod and a second guide pipe four-rib grooved drill rod. The right end of the through-pipe variable-diameter reamer is connected with the left end of the first guide pipe four-rib grooved drill rod. The right end of the second guide pipe four-rib grooved drill rod is connected with the left end of the through-pipe variable-diameter reamer. The large-diameter drill bit, the first guide pipe four-rib grooved drill rod, the through-pipe variable-diameter reamer and the second guide pipe four-rib grooved drill rod are coaxially arranged and are provided with pipelines which are in communication with each other in the axial direction. When drilling, the left end of the second guide pipe four-rib grooved drill rod is connected with a drilling machine, and drilling is performed through the large-diameter drill bit. The application optimizes the structure of the drilling tool, realizes the collaborative operation of permeability-increasing and hole-protecting, improves the gas extraction efficiency of the low-permeability coal seam, reduces the gas risk and promotes the safe and efficient production of coal mines.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of low-permeability coal seam gas extraction drilling construction, and particularly relates to a low-permeability coal seam layered reaming, permeability-increasing and hole-protecting drilling tool and a drilling method. BACKGROUND

[0002] Implementing permeability-increasing measures on low-permeability coal seams is an effective and commonly used technical means to improve the permeability of coal seams and increase extraction efficiency. The most commonly used permeability-increasing techniques in coal mines at present are hydraulic permeability-increasing and mechanical cavity-creating permeability-increasing. Hydraulic punching, hydraulic slotting and hydraulic fracturing, etc. are hydraulic permeability-increasing methods that use water as a medium, and water has a certain degree of argillization effect on coal bodies, which not only affects the permeability of coal bodies, but also weakens the strength of coal bodies around the drilling holes, thereby resulting in poor drilling hole stability. Therefore, mechanical permeability-increasing should be given priority for soft low-permeability coal seams to avoid the negative problems caused by water. Since low-permeability coal seams have low strength and poor stability, and the permeability-increasing measures further reduce the stability of the drilling holes, the drilling holes are severely collapsed, therefore, after the permeability-increasing measures are completed, it is necessary to lower the screen pipe into the drilling hole to maintain effective extraction in the later period, but the above two commonly used permeability-increasing methods and the lowering of the screen pipe are separate operations, that is, after the permeability-increasing measures are completed, the drilling tool is withdrawn and the hole-protecting screen pipe is inserted along the hole opening. Since the extraction drilling holes are collapsed, many hole-protecting screen pipes cannot be lowered into place, which will seriously affect the later extraction. Therefore, a low-permeability coal seam layered reaming, permeability-increasing and hole-protecting drilling tool and a drilling method are needed to realize the collaborative operation of permeability-increasing and hole protection, to improve the gas extraction efficiency of low-permeability coal seams and reduce the risk of gas leakage, and to promote safe and efficient production in coal mines. SUMMARY

[0003] The purpose of the present application is to provide a low-permeability coal seam layered reaming, permeability-increasing and hole-protecting drilling tool and a drilling method, which aims to overcome the passive situation of the separation of traditional permeability-increasing processes and screen pipe lowering, to realize the collaborative operation of permeability-increasing and hole protection by optimizing the structure of the drilling tool, to improve the gas extraction efficiency of low-permeability coal seams, to reduce the risk of gas leakage, and to promote safe and efficient production in coal mines.

[0004] To achieve the above purpose, the present application adopts the following technical solutions:

[0005] The low-permeability coal seam layer-by-layer reaming and permeability-increasing hole protection drilling tool comprises a large-diameter drill bit, a first guide pipe four-rib fluted drill rod, a through-pipe variable-diameter reamer and a second guide pipe four-rib fluted drill rod, the right end of the first guide pipe four-rib fluted drill rod is connected with the left end of the large-diameter drill bit, the through-pipe variable-diameter reamer is arranged between the first guide pipe four-rib fluted drill rod and the second guide pipe four-rib fluted drill rod, the right end of the through-pipe variable-diameter reamer is connected with the left end of the first guide pipe four-rib fluted drill rod, and the right end of the second guide pipe four-rib fluted drill rod is connected with the left end of the through-pipe variable-diameter reamer, the large-diameter drill bit, the first guide pipe four-rib fluted drill rod, the through-pipe variable-diameter reamer and the second guide pipe four-rib fluted drill rod are coaxially arranged and are provided with pipelines in communication with each other in the axial direction; when drilling, the left end of the second guide pipe four-rib fluted drill rod is connected with a drilling machine, and drilling is performed through the large-diameter drill bit.

[0006] The large-diameter drill bit comprises a connecting rod body and a plurality of cutting blades, the right end of the connecting rod body is formed into an arc surface part after being rounded, the cutting blades are uniformly arranged on the arc surface part in the circumferential direction, the right end of the connecting rod body is provided with a baffle, one end of the baffle is hinged to the right end of the connecting rod body, and the left end of the connecting rod body is provided with a first female joint.

[0007] The right end of the cutting blade is provided with a plurality of first cylindrical diamond composite pieces of the same size, and the lower surface of the baffle is provided with a plurality of second cylindrical diamond composite pieces of the same size.

[0008] The first guide pipe four-rib fluted drill rod comprises a first hollow rod body, a first male joint, a second female joint, a first screen pipe type push rod, a first male end support, a first female end support, a first spring seat, a first spring, a first rubber sealing ring and a first elastic retainer, the second female joint is arranged at the left end of the first hollow rod body, the first male joint is arranged at the right end of the first hollow rod body, the first male joint corresponds to the first female joint, and the large-diameter drill bit is installed at the right end of the first guide pipe four-rib fluted drill rod through the first female joint and the first male joint;

[0009] The outer surface of the first hollow rod body is provided with four first concave arc parts in left-right direction at equal intervals to form a four-ridge structure, and a plurality of first elliptical scale grooves are evenly arranged on the outer surface of the one pair of symmetrical ridges of the first hollow rod body; the first screen pipe type push rod is arranged inside the first hollow rod body, the left end of the first screen pipe type push rod is flush with the left end of the second female joint, the right end of the first screen pipe type push rod is arranged left of the right end of the first male joint, the right end of the first screen pipe type push rod is provided with a first concave groove, the left end of the first concave groove is provided with a first male end support, the right end of the first male end support is provided with a first positioning groove in the radial direction of the first hollow rod body, the right end of the first male end support is provided with a first limiting groove leftwards in the axial direction of the first screen pipe type push rod, a first spring seat is arranged at the left end of the first limiting groove, a first spring is arranged between the first spring seat and the first male end support, the left end of the first screen pipe type push rod is provided with a first outer protrusion corresponding to the first concave groove, the first outer protrusion is provided with a first mounting groove, a first rubber sealing ring is mounted in the first mounting groove, the right end of the first outer protrusion is provided with a second limiting groove in the axial direction, the right end of the second limiting groove is provided with a first female end support, the right end of the first female end support is provided with a second positioning groove in the radial direction of the first hollow rod body, and a first elastic retaining ring is arranged at the left end of the first female end support.

[0010] The through pipe variable diameter reamer comprises an outer rod body, a second male joint, a third female joint, a reaming blade, a hinged shaft and a screen pipe inner toothed rod, the third female joint is arranged at the left end of the outer rod body, the second male joint is arranged at the right end of the outer rod body, the second male joint corresponds to the second female joint, the variable diameter reamer is installed at the left end of the first guide pipe four-ridge groove drill rod through the second male joint and the second female joint, the outer rod body is provided with a first hollow groove and a second hollow groove which are symmetrical to each other, and each of the first hollow groove and the second hollow groove is provided with a reaming blade, the reaming blade comprises a cutting blade and a gear roller shaft, the gear roller shaft is arranged at the left end of the cutting blade, and the gear roller shaft is hinged to the outer rod body through the hinged shaft.

[0011] The screen pipe inner toothed rod is coaxially arranged inside the outer rod body, the left end of the screen pipe inner toothed rod is flush with the left end of the third female joint, the right end of the screen pipe inner toothed rod is arranged left of the right end of the second male joint, the right end of the screen pipe inner toothed rod is provided with a second concave groove corresponding to the first outer protrusion, the left end of the second concave groove is provided with a symmetrical groove on the outer surface of the screen pipe inner toothed rod, the left end of the groove is provided with a gear table corresponding to the gear roller shaft rightwards in the axial direction, the right end of the gear table is provided with a plurality of air holes distributed at equal intervals on the surface of the groove rightwards in the axial direction, the left side of the groove is provided with a limiting groove, the right end of the limiting groove is provided with a positioning plate, the positioning plate is fixed to the inner surface of the outer rod body, and the left side of the limiting groove is provided with a second outer protrusion corresponding to the second concave groove.

[0012] The axial length of the through pipe variable diameter reamer is 300-400 mm, the first and second hollow grooves have the same size, the radial length is 30-40 mm, the axial length is 200-250 mm, the axial length of the reaming blade is 150-200 mm, the angle between the reaming blade in the first hollow groove and the reaming blade in the second hollow groove is ≤180°, and the diameter of the air hole is 4-6 mm.

[0013] The second guide pipe four-rib groove drill rod comprises a second hollow rod body, a third male joint, a fourth female joint, a second screen pipe type push rod, a second rubber sealing ring, a second elastic stop ring, a second spring seat and a second spring.

[0014] The second screen pipe type push rod is coaxially arranged in the second hollow rod body, the left end of the second screen pipe type push rod is flush with the left end of the fourth female joint, the right end of the second screen pipe type push rod is located to the left of the right end of the third male joint, the right end of the second screen pipe type push rod is provided with a third inner recess, the third inner recess is sequentially provided with a second male end support, the right end of the second male end support is provided with a third positioning groove in the radial direction of the second hollow rod body, the right end of the second male end support is provided with a third limiting groove in the axial direction of the second screen pipe type push rod to the left, the second spring seat is arranged at the left end of the third limiting groove, and the second spring is arranged between the second spring seat and the second male end support.

[0015] The left end of the second screen pipe type push rod is provided with a third outer protrusion corresponding to the third inner recess, the third outer protrusion is provided with a second mounting groove in the axial direction, the second mounting groove is mounted with the second rubber sealing ring, the right end of the third outer protrusion is provided with a fourth limiting groove in the axial direction, the right end of the fourth limiting groove is provided with a second female end support, the right end of the second female end support is provided with a right fourth positioning groove in the radial direction of the second hollow rod body, and the left end of the second female end support is provided with the second elastic stop ring.

[0016] The diameter of the first guide pipe four-rib fluted drill rod is 80-100 mm, the length is 200-500 mm, the length of the first hollow rod body is 100-360 mm, the maximum outer diameter of the first screen pipe type push rod is 50-55 mm, the inner diameter is 35-38 mm, a gap of 5-20 mm is provided between the outer surface of the first screen pipe type push rod and the inner surface of the first hollow rod body, the axial length of the first male end support is 15-20 mm, the length of the first female end support is 15-20 mm, the axial length of the first elastic check ring is 2-5 mm, and the radial outer edge of the first elastic check ring is tangent to the radial outer edge of the first female end support;

[0017] The diameter of the second guide pipe four-rib fluted drill rod is 80-100 mm, the length is 1000-1500 mm, the length of the second hollow rod body is 800-1000 mm, the maximum outer diameter of the second screen pipe type push rod is 50-55 mm, the inner diameter is 35-38 mm, a gap of 5-20 mm is provided between the outer surface of the second screen pipe type push rod and the inner surface of the second hollow rod body, the axial length of the second male end support is 15-20 mm, the length of the second female end support is 15-20 mm, the axial length of the second elastic check ring is 2-5 mm, and the radial outer edge of the second elastic check ring is tangent to the radial outer edge of the second female end support, the first elastic check ring and the second elastic check ring are the same shape, both are horseshoe-shaped.

[0018] The drilling method is based on the low-permeability coal seam layered reaming and permeability-increasing hole protection drilling tool and includes the following steps:

[0019] (1) Assemble the low-permeability coal seam layered reaming and permeability-increasing hole protection drilling tool;

[0020] (2) Install the assembled low-permeability coal seam layered reaming and permeability-increasing hole protection drilling tool on a crawler-type drilling machine, connect the intelligent reaming operation table at the second screen pipe type push rod at the tail end of the drilling tool, and perform drilling construction.

[0021] The specific operation process of step (1) is: install the large-diameter drill bit at the right end of the first guide pipe four-rib fluted drill rod through the first female joint and the first male joint, install the through-pipe variable-diameter reamer at the left end of the first guide pipe four-rib fluted drill rod through the second male joint and the second female joint, install the second guide pipe four-rib fluted drill rod at the left end of the through-pipe variable-diameter reamer through the third male joint and the third female joint, and complete the assembly of the low-permeability coal seam layered reaming and permeability-increasing hole protection drilling tool.

[0022] The specific operation process of step (2) is that the drill tool is installed on the crawler-type drilling machine through the fourth male joint and the fourth female joint matched with the fourth male joint arranged on the crawler-type drilling machine, and the intelligent reaming operation platform is connected at the second screen pipe type push rod at the tail end of the drill tool, after the drilling machine is started, the drill tool starts drilling under the driving of the drilling machine, and the intelligent reaming operation platform is used for precise automatic layered reaming and permeability improvement together with the second screen pipe type push rod and the first screen pipe type push rod.

[0023] The present application realizes layered reaming and permeability improvement by controlling the opening and closing angle of the reamer blade through the movable push rod and spring structure arranged inside the drill tool, and the screen pipe structure of the push rod enables the next screen pipe to be directly carried out after the reaming and permeability improvement is completed without the need of withdrawing the drill tool for screen pipe, so that the permeability improvement and hole protection are simultaneously carried out, the process operation complexity is effectively reduced, the gas extraction efficiency of low-permeability coal seams is improved, the gas risk in the process of coal mining is reduced, and the safety of miners and production efficiency are ensured.

[0024] In summary, the present application has scientific design and reasonable structure, and can realize the collaborative operation of permeability improvement and hole protection, thereby improving the gas extraction efficiency of low-permeability coal seams, reducing the gas risk, and promoting the safety production of coal mines. BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1 is a structural schematic view of the layered reaming and permeability improvement and hole protection drill tool for low-permeability coal seams according to the present application.

[0026] Fig. 2 is an A-A sectional view of Fig. 1.

[0027] Figure 3 is Figure 2 Fig. 3 is an enlarged view of the middle A part.

[0028] Fig. 4 is a front view of the large-diameter drill bit according to the present application.

[0029] Fig. 5 is a B-B sectional view of Figure 4 .

[0030] Fig. 6 is a right view of Fig. 4.

[0031] Fig. 7 is a front view of the first guide pipe four-rib grooved drill rod according to the present application.

[0032] Figure 8 Fig. 8 is a C-C sectional view of Fig. 7.

[0033] Figure 9 Fig. 9 is a left view of Fig. 7.

[0034] Fig. 10 is a front view of the through-pipe variable-diameter reamer according to the present application.

[0035] Fig. 11 is a D-D sectional view of Figure 10 .

[0036] Figure 12 for Figure 10 Top view.

[0037] Figure 13 This is a three-dimensional structural diagram of the variable diameter expander for the through-pipe in this application.

[0038] Figure 14 is a front view of the second guide tube with four-sided grooved drill rod of this application.

[0039] Figure 15 is Figure 14 EE cross-section.

[0040] Figure 16 for Figure 14 The left view.

[0041] Figure 17 This is a schematic diagram of the structure supporting the first public end of this application.

[0042] Figure 18 This is a schematic diagram of the structure of the first elastic retaining ring of this application.

[0043] Figure 19 is a schematic diagram of the structure of the low-permeability coal seam layered borehole enlargement and permeability enhancement drilling tool of Embodiment 2 of this application.

[0044] Figure 20 is a schematic diagram of the structure of the first guide tube with four-sided grooved drill rod in Embodiment 2 of this application.

[0045] Figure 21 is a schematic diagram of the structure of the second guide tube with four-sided grooved drill rod according to Embodiment 2 of this application. Detailed Implementation

[0046] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0047] Example 1

[0048] like Figures 1-18 As shown, a drilling tool for layered borehole enlargement and permeability enhancement in low-permeability coal seams includes a large-diameter drill bit 1, a first guide tube with four-sided grooved drill rod 2, a through-tube variable-diameter reamer 3, and a second guide tube with four-sided grooved drill rod 4. The right end of the first guide tube with four-sided grooved drill rod 2 is connected to the left end of the large-diameter drill bit 1. The through-tube variable-diameter reamer 3 is positioned between the first guide tube with four-sided grooved drill rod 2 and the second guide tube with four-sided grooved drill rod 4. The right end of the hole tool 3 is connected to the left end of the first guide tube square grooved drill rod 2, and the right end of the second guide tube square grooved drill rod 4 is connected to the left end of the through pipe variable diameter expander 3. The large diameter drill bit 1, the first guide tube square grooved drill rod 2, the through pipe variable diameter expander 3, and the second guide tube square grooved drill rod 4 are coaxially arranged and have interconnected pipes along the axial direction. When drilling, the left end of the second guide tube square grooved drill rod 4 is connected to the drilling machine, and drilling is performed through the large diameter drill bit 1.

[0049] The large-diameter drill bit 1 comprises a connecting rod body 6 and a plurality of cutting blades 5, the right end of the connecting rod body 6 is rounded to form an arc surface, the cutting blades 5 are uniformly arranged on the arc surface in the circumferential direction, the right end of the connecting rod body 6 is provided with a baffle 10, one end of the baffle 10 is hinged to the right end of the connecting rod body 6, and the left end of the connecting rod body 6 is provided with a first female joint 9;

[0050] The right end of the cutting blade 5 is provided with a plurality of first cylindrical diamond composite pieces 7 with the same size, and the lower surface of the baffle 10 is provided with a plurality of second cylindrical diamond composite pieces 63 with the same size. The overall diameter of the large-diameter drill bit 1 is 100-120 mm, the length is 90-110 mm, the shape of the cutting blade 5 is a special-shaped hexagon which is stretched by 30° around the axis of the connecting rod body 6 to form a special-shaped body, the cutting blades 5 are distributed at equal intervals along the top of the connecting rod body 6, the number of the cutting blades 5 is 4, the diameter of the first cylindrical diamond composite piece 7 is 12 mm, and the thickness is 7 mm, the top and tail of the cutting blade 5 are cut, the diameter of the left end column of the connecting rod body 6 is 89 mm, and the height is 72 mm, the overall height of the connecting rod body 6 is 79.5 mm, the connecting rod body 6 is provided with a channel 8 at the axial center, the inner diameter of the channel 8 is 47-79.2 mm, the length of the baffle 10 is 56 mm, and the thickness is 8 mm, the number of the second cylindrical diamond composite pieces 63 is 4, the diameter is 8 mm, and the length is 11 mm.

[0051] The first guide pipe four-rib groove drill rod 2 comprises a first hollow rod body 11, a first male joint 12, a second female joint 13, a first screen pipe type push rod 15, a first male end support 17, a first female end support 25, a first spring seat 20, a first spring 21, a first rubber sealing ring 23 and a first elastic retainer 27, the second female joint 13 is arranged at the left end of the first hollow rod body 11, the first male joint 12 is arranged at the right end of the first hollow rod body 11, the first male joint 12 corresponds to the first female joint 9, and the large-diameter drill bit 1 is installed at the right end of the first guide pipe four-rib groove drill rod 2 through the first female joint 9 and the first male joint 12;

[0052] The outer surface of the first hollow rod body 11 is provided with four first concave circular arc parts in the left-right direction at equal intervals, so that the first hollow rod body 11 forms a four-ridge structure. A plurality of first elliptical scale-shaped grooves 14 are uniformly arranged on the outer surface of the pair of symmetrical ridges of the first hollow rod body 11. The first elliptical scale-shaped grooves 14 are arranged on the outer surface of the ridges. A first screen pipe type push rod 15 is arranged inside the first hollow rod body 11. The left end of the first screen pipe type push rod 15 is flush with the left end of the second female joint 13. The right end of the first screen pipe type push rod 15 is arranged to the left of the right end of the first male joint 12. The right end of the first screen pipe type push rod 15 is provided with a first recessed groove 16. The left end of the first recessed groove 16 is provided with a first male end support 17. The right end of the first male end support 17 is provided with a first positioning groove 18 in the radial direction of the first hollow rod body 11. The right end of the first male end support 17 is provided with a first limiting groove 19 in the axial direction to the left of the first screen pipe type push rod 15. A first spring seat 20 is arranged at the left end of the first limiting groove 19. A first spring 21 is arranged between the first spring seat 20 and the first male end support 17. The left end of the first screen pipe type push rod 15 is provided with a first external protrusion 22 corresponding to the first recessed groove 16. The first external protrusion 22 is provided with a first mounting groove. A first rubber sealing ring 23 is mounted in the first mounting groove. The right end of the first external protrusion 22 is provided with a second limiting groove 24 in the axial direction. The right end of the second limiting groove 24 is provided with a first female end support 25. The right end of the first female end support 25 is provided with a second positioning groove 26 in the radial direction of the first hollow rod body 11. A first elastic retaining ring 27 is arranged at the left end of the first female end support 25.

[0053] The through pipe variable diameter reamer 3 comprises an outer rod body 28, a second male joint 29, a third female joint 30, reaming blades 32, a hinge shaft 35, and a screen pipe inner tooth rod 36. The third female joint 30 is arranged at the left end of the outer rod body 28. The second male joint 29 is arranged at the right end of the outer rod body 28. The second male joint 29 corresponds to the second female joint 13. The variable diameter reamer is installed at the left end of the first guide pipe four-ridge groove drill rod 2 through the second male joint 29 and the second female joint 13. The outer rod body 28 is provided with a first hollow groove 31 and a second hollow groove 32 which are symmetrical to each other. One reaming blade 32 is arranged in each of the first hollow groove 31 and the second hollow groove 32. The reaming blade 32 comprises a cutting piece 33 and a gear roller shaft 34. The gear roller shaft 34 is arranged at the left end of the cutting piece 33. The gear roller shaft 34 is hinged to the outer rod body 28 through the hinge shaft 35.

[0054] The screen inner tooth rod 36 is coaxially arranged inside the outer rod body 28, the left end of the screen inner tooth rod 36 is flush with the left end of the third female joint 30, the right end of the screen inner tooth rod 36 is arranged left to the right end of the second male joint 29, the right end of the screen inner tooth rod 36 is provided with the second inner groove 37 corresponding to the first outer protrusion 22, the left end of the second inner groove 37 is provided with the symmetrical groove 38 along the outer surface of the screen inner tooth rod 36, the left end of the groove 38 is provided with the gear table 39 corresponding to the gear roller 34 along the axial direction to the right, the right end of the gear table 39 is provided with the air hole 40 distributed at equal intervals on the surface of the groove 38 along the axial direction to the right, the left side of the groove 38 is provided with the limit movement groove 41, the right end of the limit movement groove 41 is provided with the positioning plate 42, the positioning plate 42 is fixed to the inner surface of the outer rod body 28, and the left side of the limit movement groove 41 is provided with the second outer protrusion 43 corresponding to the second inner groove 37.

[0055] The axial length of the through pipe variable diameter reamer 3 is 300-400 mm, the sizes of the first air groove 31 and the second air groove are the same, the radial length is 30-40 mm, the axial length is 200-250 mm, the axial length of the reaming blade 32 is 150-200 mm, the angle between the reaming blade 32 in the first air groove 31 and the reaming blade 32 in the second air groove is ≤180°, and the diameter of the air hole 40 is 4-6 mm. The radial length of the reaming blade 32 is equal to the radial length of the first air groove 31 and the second air groove, the cutting blades 33 of the two reaming blades 32 are distributed in the cutting direction of the rotary direction of the installation drill, the cutting blade 33 is a kind of boss structure as a whole, the hinge shaft 35 connects the gear roller 34 and the outer rod body 28 in one body, the screen inner tooth rod 36 is coaxially arranged with the outer rod body 28, the maximum outer diameter and the minimum inner diameter of the screen inner tooth rod 36 are the same as those of the first screen type push rod 15, the length of the limit movement groove 41 is the distance that the screen inner tooth rod 36 moves from the initial state to the state of 180°, the positioning plate 42 is a cylindrical structure formed by removing a small cylinder along the axial center, and the positioning plate 42 is fixed to the inner surface of the outer rod body 28.

[0056] The second four-rib fluted drill rod 4 comprises a second hollow rod body 44, a third male joint 45, a fourth female joint 46, a second screen type push rod 48, a second rubber sealing ring 56, a second elastic stop ring 60, a second spring seat 53, and a second spring 54. The third male joint 45 is arranged at the right end of the second hollow rod body 44 and corresponds to the third female joint 30. The second four-rib fluted drill rod 4 is connected to the left end of the variable-diameter hole reamer 3 through the third male joint 45 and the third female joint 30. Four left-right direction second concave arc portions are arranged on the outer surface of the second hollow rod body 44 in a circumferential direction to form a four-rib structure. A plurality of second elliptical scale-like fluted grooves 47 are arranged on a pair of symmetrical ribs of the second hollow rod body 44 in an axial direction at equal intervals. The number of the second elliptical scale-like fluted grooves 47 is 10. The major axis direction of the elliptical shape is 30° to the axial direction of the rod body. The maximum depth of the fluted groove 47 is 2 mm.

[0057] The second screen type push rod 48 is coaxially arranged in the second hollow rod body 44. The left end of the second screen type push rod 48 is flush with the left end of the fourth female joint 46. The right end of the second screen type push rod 48 is located to the left of the right end of the third male joint 45. The right end of the second screen type push rod 48 is provided with a third inner recess 49. The third inner recess 49 is provided with a second male end support 50. The right end of the second male end support 50 is provided with a third positioning groove 51 in the radial direction of the second hollow rod body 44. The right end of the second male end support 50 is provided with a third limiting groove 52 in the axial direction to the left of the second screen type push rod 48. The second spring seat 53 is arranged at the left end of the third limiting groove 52. The second spring 54 is arranged between the second spring seat 53 and the second male end support 50.

[0058] The left end of the second screen type push rod 48 is provided with a third outer protrusion 55 corresponding to the third inner recess 49. The third outer protrusion 55 is provided with a second mounting groove in the axial direction. The second mounting groove is mounted with the second rubber sealing ring 56. The right end of the third outer protrusion 55 is provided with a fourth limiting groove 57 in the axial direction. The right end of the fourth limiting groove 57 is provided with a second female end support 58. The right end of the second female end support 58 is provided with a right fourth positioning groove 59 in the radial direction of the second hollow rod body 44. The left end of the second female end support 58 is provided with the second elastic stop ring 60.

[0059] The diameter of the first guide pipe four-rib grooved drill rod 2 is 80-100 mm, the length is 200-500 mm, the length of the first hollow rod body 11 is 100-360 mm, the maximum outer diameter of the first screen pipe push rod 15 is 50-55 mm, the inner diameter is 35-38 mm, a gap of 5-20 mm is provided between the outer surface of the first screen pipe push rod 15 and the inner surface of the first hollow rod body 11, the axial length of the first male end support 17 is 15-20 mm, the length of the first female end support 25 is 15-20 mm, the axial length of the first elastic retainer 27 is 2-5 mm, the radial outer edge of the first elastic retainer 27 is tangent to the radial outer edge of the first female end support 25; the first male end support 17 is a special-shaped body with a hollow cylindrical outer surface provided with three circumferentially equidistantly distributed rib structures, specifically, the first male end support 17 includes a hollow cylindrical body 61 and three ribs 62 provided on the cylindrical body. The radial minimum diameter of the first positioning groove 18 is greater than the maximum outer diameter of the first screen pipe push rod 15, the radial maximum diameter of the first positioning groove 18 is equal to the radial maximum diameter of the first male end support 17, the radial minimum diameter of the first limiting groove 19 is equal to the radial minimum diameter of the first male end support 17, the first spring seat 20 is a cored cylindrical body with the same size as the hollow cylindrical part of the first male end support 17, the axial length of the first male end support 17 is 15 mm, the shape of the first female end support 25 is the same as that of the first male end support 17, the radial minimum diameter of the first female end support 25 is less than or equal to the radial minimum diameter of the first male end support 17, the radial minimum diameter of the first limiting groove 19 is equal to the radial minimum diameter of the first female end support 25, the radial minimum diameter of the second positioning groove 26 is greater than the maximum outer diameter of the first screen pipe push rod 15, the radial maximum diameter of the second positioning groove 26 is equal to the radial maximum diameter of the first female end support 25, and the axial length of the first female end support 25 is 15 mm.

[0060] The diameter of the second guide pipe four-rib grooved drill rod 4 is 80-100 mm, the length is 1000-1500 mm, the length of the second hollow rod body 44 is 800-1000 mm, the maximum outer diameter of the second screen pipe push rod 48 is 50-55 mm, the inner diameter is 35-38 mm, a gap of 5-20 mm is provided between the outer surface of the second screen pipe push rod 48 and the inner surface of the second hollow rod body 44, the axial length of the second male end support 50 is 15-20 mm, the length of the second female end support 58 is 15-20 mm, the axial length of the second elastic retainer 60 is 2-5 mm, the radial outer edge of the second elastic retainer 60 is tangent to the radial outer edge of the second female end support 58, the first elastic retainer 27 and the second elastic retainer 60 are the same in shape and are both horseshoe-shaped, and the male joint and the female joint are connected through thread connection or clamp connection.

[0061] The second male end support 50 is a hollow cylinder with three circumferentially spaced convex ridges on its outer surface. The minimum radial diameter of the third positioning groove 51 is greater than the maximum outer diameter of the second screen tube push rod 48, and the maximum radial diameter of the third positioning groove 51 is equal to the maximum radial diameter of the second male end support 50. The minimum radial diameter of the third limiting groove 52 is equal to the minimum radial diameter of the second male end support 50. The second spring seat 53 is a coreless cylinder with the same size as the hollow cylindrical part of the second male end support 50. The axial length is 15mm. The shape of the second female end support 58 is the same as that of the second male end support 50. The minimum radial diameter of the second female end support 58 is less than or equal to the minimum radial diameter of the second male end support 50. The minimum radial diameter of the fourth limiting groove 57 is equal to the minimum radial diameter of the second female end support 58. The minimum radial diameter of the fourth positioning groove 59 is greater than the maximum outer diameter of the second screen tube push rod 48. The maximum radial diameter of the fourth positioning groove 59 is equal to the maximum radial diameter of the second female end support 58. The axial length of the second female end support 58 is 15mm.

[0062] This application achieves layered borehole enlargement and permeability enhancement by controlling the opening and closing angle of the reamer blades through a movable push rod and spring structure inside the drill bit. At the same time, the push rod's screenable tube structure allows for direct screening after borehole enlargement and permeability enhancement without removing the drill bit and then screening the tube. This enables simultaneous permeability enhancement and borehole protection, effectively reducing the complexity of the process, improving the gas extraction efficiency of low-permeability coal seams, reducing the gas risk during coal mining, and ensuring miner safety and production efficiency.

[0063] In summary, this application has a scientific design and reasonable structure, which can achieve the synergistic operation of permeability enhancement and borehole protection, thereby improving the gas extraction efficiency of low-permeability coal seams, reducing gas risks, and promoting safe coal mine production.

[0064] Example 2

[0065] like Figures 19-21 As shown, the difference from Embodiment 1 is that the elliptical scale-like grooves on the outer surfaces of the first hollow rod 11 and the second hollow rod 44 in Embodiment 1 are changed from the one pair of symmetrical sides in Embodiment 1 to two pairs of symmetrical sides. Other structural parameters are the same as in Embodiment 1, and the working principle is the same as in Embodiment 1.

[0066] Example 3

[0067] The drilling method, implemented using the aforementioned low-permeability coal seam layered enlargement and permeability enhancement drilling tool, includes the following steps:

[0068] (1) Assemble the drilling tools for layered enlargement and permeability enhancement in low-permeability coal seams;

[0069] (2) The assembled low-permeability coal seam layered reaming and permeability-increasing hole protection drilling tool is installed on the crawler-type drilling machine, the intelligent reaming operation platform is connected at the second screen pipe type push rod 48 at the tail end of the drilling tool, and drilling construction is carried out.

[0070] The specific operation process of step (1) is that the large-diameter drill bit 1 is installed at the right end of the first guide pipe four-rib grooved drill rod 2 through the first female joint 9 and the first male joint 12, the through-pipe variable-diameter reamer 3 is installed at the left end of the first guide pipe four-rib grooved drill rod 2 through the second male joint 29 and the second female joint 13, and the second guide pipe four-rib grooved drill rod 4 is installed at the left end of the through-pipe variable-diameter reamer 3 through the third male joint 45 and the third female joint 30, thereby completing the assembly of the low-permeability coal seam layered reaming and permeability-increasing hole protection drilling tool.

[0071] The specific operation process of step (2) is that the drilling tool is installed on the crawler-type drilling machine through the fourth male joint and the fourth female joint 46 matched with the fourth male joint arranged on the crawler-type drilling machine, the intelligent reaming operation platform is connected at the second screen pipe type push rod 48 at the tail end of the drilling tool, after the drilling machine is started, the drilling tool starts drilling under the driving of the drilling machine, and in the drilling process, the intelligent reaming operation platform is used for precise automatic layered reaming and permeability-increasing together with the second screen pipe type push rod 48 and the first screen pipe type push rod 15, so as to increase the gas permeability and flowability, cooperate with the screen pipe structure arranged in the drilling tool, not only facilitate the lower screen pipe, but also help to protect the drilling and improve the gas extraction efficiency, and help to overcome the problems of low efficiency and low safety caused by the passive situation of separating the penetrating and permeability-increasing process from the lower screen pipe.

[0072] The above examples are only used to illustrate but not to limit the technical solutions of the present application. Although the present application is described in detail with reference to the above examples, those skilled in the art should understand that the present application can still be modified or replaced equivalently without departing from the spirit and scope of the present application, and any modification or partial replacement should be covered in the scope of the claims of the present application.

Claims

1. A drilling tool for layered borehole enlargement and permeability enhancement in low-permeability coal seams, characterized in that: The application relates to a drilling device, which comprises a large-diameter drill bit, a first guide pipe four-rib fluted drill rod, a through-pipe variable-diameter reamer and a second guide pipe four-rib fluted drill rod. The first guide pipe four-rib fluted drill rod comprises a first hollow rod body, a first male joint, a second female joint, a first screen pipe type push rod, a first male end support, a first female end support, a first spring seat, a first spring, a first rubber sealing ring and a first elastic baffle. The outer surface of the first hollow rod body is provided with four first concave circular arc portions in the left-right direction and at equal intervals, so that the first hollow rod body forms a four-rib structure; a plurality of first elliptical scale flutes are arranged on a pair of symmetrical ribs of the outer surface of the first hollow rod body; the first screen pipe type push rod is arranged in the first hollow rod body, and the left end of the first screen pipe type push rod is flush with the left end of the second female joint; the right end of the first screen pipe type push rod is arranged on the left side of the right end of the first male joint; the right end of the first screen pipe type push rod is provided with a first recess; the left end of the first recess is provided with the first male end support; the right end of the first male end support is provided with a first positioning groove in the radial direction of the first hollow rod body; the right end of the first male end support is provided with a first limiting groove in the axial direction of the first screen pipe type push rod; the first spring seat is arranged at the left end of the first limiting groove; the first spring is arranged between the first spring seat and the first male end support; the left end of the first screen pipe type push rod is provided with a first external protrusion corresponding to the first recess; the first external protrusion is provided with a first mounting groove; the first mounting groove is provided with the first rubber sealing ring; the right end of the first external protrusion is provided with a second limiting groove in the axial direction; the right end of the second limiting groove is provided with the first female end support; the right end of the first female end support is provided with a second positioning groove in the radial direction of the first hollow rod body; and the first elastic baffle is arranged at the left end of the first female end support.

2. The low-permeability coal-seam zonal reaming and permeability-improving hole-protection drill tool according to claim 1, characterized in that: The large-diameter drill bit comprises a connecting rod body and a plurality of cutting blades; the right end of the connecting rod body is provided with an arc surface portion after being rounded; the cutting blades are uniformly arranged on the arc surface portion in the circumferential direction; the right end of the connecting rod body is provided with a baffle; one end of the baffle is hinged to the right end of the connecting rod body; and the left end of the connecting rod body is provided with the first female joint. The right end of the cutting blade wing is provided with a plurality of first cylindrical diamond composite pieces with the same size, and the lower surface of the baffle is provided with a plurality of second cylindrical diamond composite pieces with the same size.

3. The low-permeability coal-seam zonal reaming and permeability-improving hole-protection drill tool according to claim 2, characterized in that: The through pipe variable diameter reamer comprises an outer rod body, a second male joint, a third female joint, a reaming blade, a hinged shaft, a sieveable pipe inner toothed rod, the third female joint is arranged at the left end of the outer rod body, the second male joint is arranged at the right end of the outer rod body, the second male joint corresponds to the second female joint, the through pipe variable diameter reamer is installed at the left end of the first guide pipe four-rib fluted drill rod through the second male joint and the second female joint, the outer rod body is provided with a first hollow groove and a second hollow groove which are symmetrical to each other, and one reaming blade is arranged in each of the first hollow groove and the second hollow groove, the reaming blade comprises a cutting piece and a gear roller shaft, the gear roller shaft is arranged at the left end of the cutting piece, and the gear roller shaft is hinged to the outer rod body through the hinged shaft; The sieveable pipe inner toothed rod is coaxially arranged in the outer rod body, the left end of the sieveable pipe inner toothed rod is flush with the left end of the third female joint, the right end of the sieveable pipe inner toothed rod is arranged at the left side of the right end of the second male joint, the right end of the sieveable pipe inner toothed rod is provided with a second inner recess groove corresponding to the first outer protrusion, the second inner recess groove is provided with symmetrical fluted grooves along the outer surface of the sieveable pipe inner toothed rod at the left end, the fluted groove is provided with a gear table corresponding to the gear roller shaft along the axial direction to the right at the left end, the gear table is provided with air holes with equal intervals on the surface of the fluted groove along the axial direction to the right at the right end, the fluted groove is provided with a limited displacement groove at the left side, the limited displacement groove is provided with a positioning plate at the right end, the positioning plate is fixed to the inner surface of the outer rod body, and the left side of the limited displacement groove is provided with a second outer protrusion corresponding to the second inner recess groove.

4. The low-permeability coal-seam zonal reaming and permeability-improving hole-protection drill tool according to claim 3, characterized in that: The axial length of the through pipe variable diameter reamer is 300-400 mm, the sizes of the first hollow groove and the second hollow groove are the same, the radial length is 30-40 mm, the axial length is 200-250 mm, the axial length of the reaming blade is 150-200 mm, the angle between the reaming blade in the first hollow groove and the reaming blade in the second hollow groove is ≤180°, and the diameter of the air hole is 4-6 mm.

5. The low-permeability coal-seam, separate-hole, hole-enlarging, and hole- opening drill tool according to claim 4, characterized in that: The second guide pipe four-rib fluted drill rod comprises a second hollow rod body, a third male joint, a fourth female joint, a second sieveable pipe type push rod, a second rubber sealing ring, a second elastic retainer, a second spring seat and a second spring, the third male joint is arranged at the right end of the second hollow rod body, the third male joint corresponds to the fourth female joint, the second guide pipe four-rib fluted drill rod is connected with the left end of the through pipe variable diameter reamer through the third male joint and the fourth female joint, four second inner recessed arc parts which are distributed with equal intervals in the left-right direction are arranged on the outer surface of the second hollow rod body in a circle, so that the second hollow rod body forms a four-rib structure, and a plurality of second elliptical scale-shaped fluted grooves are arranged on one pair of symmetrical ribs of the outer surface of the second hollow rod body along the axial direction with equal intervals; The second screen pipe type push rod is coaxially arranged in the second hollow rod body, the left end of the second screen pipe type push rod is flush with the left end of the fourth female joint, the right end of the second screen pipe type push rod is located left of the right end of the third male joint, the right end of the second screen pipe type push rod is provided with a third inner groove, the second male end support is arranged in the third inner groove, the right end of the second male end support is provided with a third positioning groove in the radial direction of the second hollow rod body, the right end of the second male end support is provided with a third limiting groove in the axial direction of the second screen pipe type push rod, a second spring seat is arranged at the left end of the third limiting groove, and a second spring is arranged between the second spring seat and the second male end support; The left end of the second screen pipe type push rod is provided with a third outer protrusion corresponding to the third inner groove, the third outer protrusion is provided with a second installation groove in the axial direction, the second installation groove is provided with a second rubber sealing ring, the right end of the third outer protrusion is provided with a fourth limiting groove in the axial direction, the right end of the fourth limiting groove is provided with a second female end support, the right end of the second female end support is provided with a fourth positioning groove in the radial direction of the second hollow rod body, and the left end of the second female end support is provided with a second elastic stop ring.

6. The low-permeability coal-seam, separate-hole, hole-enlarging, and hole- opening drill tool according to claim 5, characterized in that: The diameter of the first guide pipe four-rib groove drill rod is 80-100 mm, the length is 200-500 mm, the length of the first hollow rod body is 100-360 mm, the maximum outer diameter of the first screen pipe type push rod is 50-55 mm, the inner diameter is 35-38 mm, a gap of 5-20 mm is arranged between the outer surface of the first screen pipe type push rod and the inner surface of the first hollow rod body, the axial length of the first male end support is 15-20 mm, the length of the first female end support is 15-20 mm, the axial length of the first elastic stop ring is 2-5 mm, and the radial outer edge of the first elastic stop ring is tangent to the radial outer edge of the first female end support; The diameter of the second guide pipe four-rib groove drill rod is 80-100 mm, the length is 1000-1500 mm, the length of the second hollow rod body is 800-1000 mm, the maximum outer diameter of the second screen pipe type push rod is 50-55 mm, the inner diameter is 35-38 mm, a gap of 5-20 mm is arranged between the outer surface of the second screen pipe type push rod and the inner surface of the second hollow rod body, the axial length of the second male end support is 15-20 mm, the length of the second female end support is 15-20 mm, the axial length of the second elastic stop ring is 2-5 mm, the radial outer edge of the second elastic stop ring is tangent to the radial outer edge of the second female end support, the first elastic stop ring and the second elastic stop ring are the same shape, and are all horseshoe-shaped.

7. A drilling method based on the low-permeability coal-seam layered reaming and permeability-increasing hole-protecting drilling tool as claimed in claim 6, characterized in that: The method comprises the following steps: (1) Assembling the low-permeability coal seam layered reaming and permeability increasing hole protection drilling tool; (2) Installing the assembled low-permeability coal seam layered reaming and permeability increasing hole protection drilling tool on a crawler-type drilling machine, connecting an intelligent reaming operation table at the second screen pipe type push rod at the tail end of the drilling tool, and performing drilling construction.

8. The method of drilling according to claim 7, characterized in that: The specific operation process of step (1) is: installing the large-diameter drill bit on the right end of the first guide pipe four-rib grooved drill rod through the first female joint and the first male joint, installing the through-pipe variable-diameter reamer on the left end of the first guide pipe four-rib grooved drill rod through the second male joint and the second female joint, and installing the second guide pipe four-rib grooved drill rod on the left end of the through-pipe variable-diameter reamer through the third male joint and the third female joint, thereby completing the assembly of the low-permeability coal seam layered reaming and permeability-increasing hole protection drilling tool.

9. The method of drilling a borehole according to claim 7, wherein: The specific operation process of step (2) is: installing the drilling tool on the crawler-type drilling machine through the fourth male joint and the fourth female joint matched with the fourth male joint arranged on the crawler-type drilling machine, connecting the intelligent reaming operation platform at the second screen-pipe type push rod at the tail end of the drilling tool, starting the drilling machine, and then starting the drilling under the driving of the drilling machine; during the drilling process, the intelligent reaming operation platform is used in combination with the second screen-pipe type push rod and the first screen-pipe type push rod for precise automatic layered reaming and permeability-increasing.

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