Layered hole expanding, permeability increasing and hole protecting drilling tool for low-permeability coal seam and hole drilling method

Abstract

The invention discloses a low-permeability coal seam layering hole expanding, permeability increasing and hole protecting drilling tool and a drilling method. The right end of a first guide pipe four-edge grooving drilling rod of the drilling tool is connected with the left end of a large-drift-diameter drill bit, and a through pipe variable-diameter reamer is arranged between the first guide pipe four-edge grooving drilling rod and a second guide pipe four-edge grooving drilling rod; the right end of the through pipe variable-diameter reamer is connected with the left end of the first guide pipe four-edge grooving drill rod, and the right end of the second guide pipe four-edge grooving drill rod is connected with the left end of the through pipe variable-diameter reamer. The large-drift-diameter drill bit, the first guide pipe four-edge grooving drill rod, the through pipe variable-diameter reamer and the second guide pipe four-edge grooving drill rod are coaxially arranged and provided with pipelines communicated with one another in the axial direction. During drilling, the left end of the second guide pipe four-edge grooving drill rod is connected with a drilling machine, and drilling is conducted through a large-drift-diameter drill bit. By optimizing the drilling tool structure, cooperative operation of permeability increasing and hole protecting is achieved, so that the low-permeability coal seam gas extraction efficiency is improved, the gas risk is reduced, and safe and efficient production of a coal mine is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling construction for gas extraction in low-permeability coal seams, and in particular relates to a drilling tool and a drilling method for layered hole expansion, permeability enhancement and hole protection in low-permeability coal seams. Background Art

[0002] Implementing permeability enhancement measures for low-permeability coal seams is an effective and common technical means to improve the permeability of coal seams and increase extraction efficiency. At present, the most commonly used permeability enhancement technologies in coal mines are hydraulic permeability enhancement and mechanical cavitation permeability enhancement. Hydraulic permeability enhancement methods such as hydraulic punching, hydraulic cutting, and hydraulic fracturing use water as a medium, and water has a certain degree of mudification effect on the coal body, which not only affects the permeability of the coal body, but also weakens the strength of the coal body around the borehole, resulting in poor borehole stability. Therefore, mechanical permeability enhancement should be given priority for permeability enhancement of soft and low-permeability coal seams, which can avoid the negative problems caused by water. Since the low-permeability coal seam has low strength and poor stability, and the adoption of permeability enhancement measures will further reduce the stability of the borehole, the borehole collapses seriously. Therefore, after the permeability enhancement measures are completed, the placement of screens to protect the borehole is a necessary technical measure to maintain effective extraction in the later stage. However, the above two commonly used permeability enhancement methods and the placement of screens are operated separately, that is, after the permeability enhancement measures are completed, the drill is withdrawn and the screen is inserted along the hole mouth. Due to the collapse of the extraction borehole, many screens cannot be put into place, which will seriously affect the later extraction. Therefore, there is a need for a low-permeability coal seam layered hole expansion and permeability protection drill and drilling method that can realize the coordinated operation of permeability enhancement and hole protection to improve the gas extraction efficiency of low-permeability coal seams and reduce the risk of gas leakage. Summary of the invention

[0003] The purpose of the present invention is to provide a low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drill tool and drilling method, aiming to overcome the passive situation of the traditional permeability enhancement process being separated from the lower screen pipe, and to achieve the coordinated operation of permeability enhancement and hole protection by optimizing the drill tool structure, thereby improving the gas extraction efficiency of low-permeability coal seams, reducing gas risks, and promoting safe and efficient production in coal mines.

[0004] To achieve the above object, the present invention adopts the following technical solution: A low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool comprises a large-diameter drill bit, a first guide tube four-sided grooved drill rod, a through-tube variable-diameter reamer and a second guide tube four-sided grooved drill rod, the right end of the first guide tube four-sided grooved drill rod is connected to the left end of the large-diameter drill bit, the through-tube variable-diameter reamer is arranged between the first guide tube four-sided grooved drill rod and the second guide tube four-sided grooved drill rod, the right end of the through-tube variable-diameter reamer is connected to the left end of the first guide tube four-sided grooved drill rod, the right end of the second guide tube four-sided grooved drill rod is connected to the left end of the through-tube variable-diameter reamer, the large-diameter drill bit, the first guide tube four-sided grooved drill rod, the through-tube variable-diameter reamer and the second guide tube four-sided grooved drill rod are coaxially arranged and have mutually connected pipes along the axial direction; when drilling, the left end of the second guide tube four-sided grooved drill rod is connected to the drilling rig, and drilling is performed through the large-diameter drill bit.

[0005] 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 rounded to form an arc surface, and the cutting blades are evenly arranged on the arc surface along the circumference. A baffle is arranged at the right end of the connecting rod body, and one end of the baffle is hinged to the right end of the connecting rod body. A first female joint is arranged at the left end of the connecting rod body. A plurality of first cylindrical diamond composite sheets of the same size are arranged at the right end of the cutting blade, and a plurality of second cylindrical diamond composite sheets of the same size are arranged on the lower surface of the baffle.

[0006] The first guide tube four-sided groove drill rod comprises a first hollow rod body, a first male joint, a second female joint, a first screen tube 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 retaining ring. 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 tube four-sided groove drill rod through the first female joint and the first male joint. The outer surface of the first hollow rod body is provided with four first concave arc portions in the left and right directions at equal intervals along the circumference, so that the first hollow rod body forms a four-convex ridge structure, and a pair of symmetrical convex ridges on the outer surface of the first hollow rod body are provided with a plurality of evenly arranged first elliptical scale grooves, the first screen tube type push rod is arranged inside the first hollow rod body, the left end of the first screen tube type push rod is flush with the left end of the second female joint, the right end of the first screen tube 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 tube type push rod is provided with a first inner groove, the left end of the first inner groove is provided with a first male end support, and the right end of the first male end support is provided with a first fixed groove along the radial direction of the first hollow rod body. A first limiting groove is arranged on the right end of the first male end support along the axial direction of the first screen tube push rod to the left, a first spring seat is arranged on the left end of the first limiting groove, a first spring is arranged between the first spring seat and the first male end support, a first outer convex head corresponding to the first inner groove is arranged on the left end of the first screen tube push rod, a first installation groove is arranged on the first outer convex head, a first rubber sealing ring is installed in the first installation groove, a second limiting groove is arranged on the right end of the first outer convex head along the axial direction, a first female end support is arranged on the right end of the second limiting groove, a second positioning groove is arranged on the right end of the first female end support along the radial direction of the first hollow rod body, and a first elastic retaining ring is arranged on the left end of the first female end support.

[0007] The through-pipe variable diameter reamer comprises an outer rod body, a second male joint, a third female joint, a reaming blade, a hinge shaft, and a screenable inner toothed rod, wherein 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 tube four-sided grooved drill rod through the second male joint and the second female joint, the outer rod body is provided with a first empty slot and a second empty slot symmetrical to each other, a reaming blade is respectively arranged in the first empty slot and the second empty slot, the reaming blade comprises a cutting blade and a gear roller, the gear roller is arranged at the left end of the cutting blade, and the gear roller is hinged to the outer rod body through the hinge shaft; The inner gear rod of the screenable tube is coaxially arranged inside the outer rod body, the left end of the inner gear rod of the screenable tube is flush with the left end of the third female joint, the right end of the inner gear rod of the screenable tube is arranged on the left side of the right end of the second male joint, and the right end of the inner gear rod of the screenable tube is provided with a second inner groove corresponding to the first outer convex head, and the left end of the second inner groove is provided with a symmetrical groove along the outer surface of the inner gear rod of the screenable tube, and a gear table corresponding to the gear roller is axially arranged to the right at the left end of the groove, and vent holes distributed at equal intervals are arranged on the groove surface at the right end of the gear table axially to the right, a limited displacement groove is provided on the left side of the groove, a positioning plate is provided on the right end of the limited displacement groove, and the positioning plate is fixed to the inner surface of the outer rod body, and a second outer convex head corresponding to the second inner groove is provided on the left side of the limited displacement groove.

[0008] The axial length of the variable diameter reamer for through-tube is 300-400mm, the first empty slot and the second empty slot have the same size, the radial length is 30-40mm, the axial length is 200-250mm, the axial length of the reaming blade is 150-200mm, the angle between the reaming blade in the first empty slot and the reaming blade in the second empty slot is ≤180°, and the diameter of the vent is 4-6mm.

[0009] The second guide tube four-sided grooved drill rod comprises a second hollow rod body, a third male joint, a fourth female joint, a second screen tube push rod, a second rubber sealing ring, a second elastic retaining ring, a second spring seat, and a second spring. The third male joint is arranged at the right end of the second hollow rod body, and the third male joint corresponds to the third female joint. The second guide tube four-sided grooved drill rod is connected to the left end of the through-tube variable diameter reamer through the third male joint and the third female joint. Four second concave arc portions in the left and right directions are evenly spaced and arranged along the circumference on the outer surface of the second hollow rod body, so that the second hollow rod body forms a four-convex ridge structure. A pair of symmetrical ridges on the outer surface of the second hollow rod body are evenly spaced along the axial direction. A plurality of second elliptical scale-shaped grooves are arranged; The second screen tube push rod is coaxially arranged inside the second hollow rod body, the left end of the second screen tube push rod is flush with the left end of the fourth female joint, the right end of the second screen tube push rod is located on the left side of the right end of the third male joint, the right end of the second screen tube push rod is provided with a third inner groove, the third inner groove sequence section is provided with a second male end support, the right end of the second male end support is provided with a third positioning groove along 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 to the left along the axial direction of the second screen tube push rod, the second spring seat is provided at the left end of the third limiting groove, and the second spring is provided between the second spring seat and the second male end support; A third outer convex head corresponding to the third inner groove is arranged at the left end of the second screen tube push rod, a second installation groove is arranged axially on the upper side of the third outer convex head, a second rubber sealing ring is installed in the second installation groove, a fourth limiting groove is arranged axially on the right end of the third outer convex head, a second female end support is arranged at the right end of the fourth limiting groove, a right fourth positioning groove is arranged radially along the second hollow rod body at the right end of the second female end support, and a second elastic retaining ring is arranged at the left end of the second female end support.

[0010] The diameter of the first guide tube four-sided 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 tube 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 tube 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 retaining ring is 2-5 mm, and the radial outer edge of the first elastic retaining ring is tangent to the radial outer edge of the first female end support; The diameter of the second guide tube four-sided grooved drill rod is 80-100mm, the length is 1000-1500mm, the length of the second hollow rod body is 800-1000mm, the maximum outer diameter of the second screen tube push rod is 50-55mm, the inner diameter is 35-38mm, and a gap of 5-20mm is provided between the outer surface of the second screen tube push rod and the inner surface of the second hollow rod body. The axial length of the second male end support is 15-20mm, the length of the second female end support is 15-20mm, the axial length of the second elastic retaining ring is 2-5mm, the radial outer edge of the second elastic retaining ring is tangent to the radial outer edge of the second female end support, and the first elastic retaining ring and the second elastic retaining ring have the same shape, both are horseshoe-shaped.

[0011] The drilling method is implemented based on the above-mentioned low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool, and comprises the following steps: (1) Assembling drilling tools for layered hole expansion, permeability enhancement and hole protection in low-permeability coal seams; (2) The assembled low-permeability coal seam layered hole expansion and permeability protection drilling tool is installed on the crawler drilling rig, and the intelligent hole expansion operating table is connected to the second screen tube push rod at the rear end of the drilling tool to carry out drilling construction.

[0012] The specific operation process of step (1) is as follows: the large-diameter drill bit is installed on the right end of the first guide tube four-sided grooved drill rod through the first female joint and the first male joint, the through-tube variable-diameter reamer is installed on the left end of the first guide tube four-sided grooved drill rod through the second male joint and the second female joint, and the second guide tube four-sided grooved drill rod is installed on the left end of the through-tube variable-diameter reamer through the third male joint and the third female joint, thereby completing the assembly of the low-permeability coal seam layered hole expansion and permeability protection drilling tool.

[0013] The specific operation process of step (2) is as follows: the drill bit is installed on the crawler drilling rig through the fourth male joint and the fourth female joint matched with the fourth male joint provided on the crawler drilling rig, and the intelligent hole expansion operating table is connected to the second screen tube push rod at the tail end of the drill bit. After starting the drilling rig, the drill bit starts drilling under the drive of the drilling rig. During the drilling process, the intelligent hole expansion operating table is equipped with the second screen tube push rod and the first screen tube push rod to perform accurate and automatic layered hole expansion and permeability enhancement.

[0014] The present application realizes layered hole expansion and permeability improvement by controlling the opening and closing angles of the reamer blades through the movable push rod and spring structure arranged inside the drill tool. At the same time, the screenable structure of the push rod makes it possible to directly lower the screen without withdrawing the drill tool and then screening after the hole expansion and permeability improvement is completed, thereby realizing simultaneous permeability improvement and hole protection, which can effectively reduce the complexity of process operations, improve the gas extraction efficiency of low-permeability coal seams, reduce the gas risk in the coal mining process, and ensure the safety of miners and production efficiency.

[0015] To sum up, the present application has a scientific design and a reasonable structure, and can realize the coordinated operation of permeability enhancement and hole protection, thereby improving the gas extraction efficiency of low-permeability coal seams, reducing gas risks, and promoting safe production in coal mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic diagram of the structure of a low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool according to the present invention.

[0017] FIG. 2 is a cross-sectional view taken along line AA of FIG. 1 .

[0018] Figure 3 yes Figure 2 Enlarged view of part A in the middle.

[0019] FIG. 4 is a front view of the large diameter drill bit of the present application.

[0020] Figure 5 Figure 4 BB cross-section diagram.

[0021] FIG. 6 is a right side view of FIG. 4 .

[0022] FIG. 7 is a front view of the four-sided grooved drill rod of the first guide tube of the present application.

[0023] Figure 8 It is the CC cross-sectional view of FIG. 7 .

[0024] Fig. 9 It is the left view of Figure 7.

[0025] FIG. 10 is a front view of the variable diameter reamer for through-tube according to the present application.

[0026] Figure 11 Fig.10 DD cross-section diagram.

[0027] Fig.12 for Fig.10 Top view of the .

[0028] Fig.13 This is a schematic diagram of the three-dimensional structure of the variable diameter reamer for pipe through pipes in this application.

[0029] FIG. 14 is a front view of the quadrangular grooved drill rod of the second guide tube of the present application.

[0030] Figure 15 Fig.14 EE cross-section diagram.

[0031] Fig.16 for Fig.14 Left view of .

[0032] Fig.17 This is a schematic diagram of the structure of the first male end support of this application.

[0033] Fig.18This is a schematic diagram of the structure of the first elastic retaining ring of the present application.

[0034] FIG. 19 is a schematic diagram of the structure of a low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool according to the second embodiment of the present application.

[0035] FIG. 20 is a schematic diagram of the structure of the four-sided grooved drill rod of the first guide tube of the second embodiment of the present application.

[0036] FIG. 21 is a schematic diagram of the structure of the quadrangular grooved drill rod of the second guide tube of the second embodiment of the present application. DETAILED DESCRIPTION

[0037] The embodiments of the present invention are further described below with reference to the accompanying drawings.

[0038] Embodiment 1 like Figure 1-18 As shown, a low-permeability coal seam layered hole enlargement, permeability enhancement and hole protection drilling tool, a low-permeability coal seam layered hole enlargement, permeability enhancement and hole protection drilling tool, comprises a large-diameter drill bit 1, a first guide tube four-sided grooved drill rod 2, a through-tube variable-diameter reamer 3 and a second guide tube four-sided grooved drill rod 4, the right end of the first guide tube 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 arranged between the first guide tube four-sided grooved drill rod 2 and the second guide tube four-sided grooved drill rod 4, and the through-tube variable-diameter reamer The right end of the hole breaker 3 is connected to the left end of the first guide tube four-sided grooved drill rod 2, the right end of the second guide tube four-sided grooved drill rod 4 is connected to the left end of the through-tube variable diameter reamer 3, the large diameter drill bit 1, the first guide tube four-sided grooved drill rod 2, the through-tube variable diameter reamer 3 and the second guide tube four-sided grooved drill rod 4 are coaxially arranged and axially arranged with interconnected pipes; when drilling, the left end of the second guide tube four-sided grooved drill rod 4 is connected to the drilling rig, and drilling is performed through the large diameter drill bit 1.

[0039] 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, and the cutting blades 5 are evenly arranged on the arc surface along the circumference. A baffle 10 is arranged at the right end of the connecting rod body 6, and one end of the baffle 10 is hinged to the right end of the connecting rod body 6. A first female joint 9 is arranged at the left end of the connecting rod body 6. A plurality of first cylindrical diamond composite sheets 7 of the same size are arranged at the right end of the cutting blade 5 , and a plurality of second cylindrical diamond composite sheets 63 of the same size are arranged on the lower surface of the baffle 10 . The overall diameter of the large-diameter drill bit 1 is 100-120 mm, and the length is 90-110 mm. The shape of the cutting blade 5 is a special-shaped body formed by rotating and stretching 30° around the axis of the connecting rod body 6. The cutting blades 5 are evenly spaced along the top of the connecting rod body 6. The number of 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 both cut off. The diameter of the left end cylinder 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. A channel 8 is provided at the axial center of the connecting rod body 6. 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, with a diameter of 8 mm and a length of 11 mm.

[0040] The first guide tube four-sided groove drill rod 2 comprises a first hollow rod body 11, a first male joint 12, a second female joint 13, a first screen-tube 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 retaining ring 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 tube four-sided groove drill rod 2 through the first female joint 9 and the first male joint 12; The outer surface of the first hollow rod body 11 is provided with four first concave arc portions in the left and right directions at equal intervals along the circumference, so that the first hollow rod body 11 forms a four-convex ridge structure, and a pair of symmetrical ridges on the outer surface of the first hollow rod body 11 are provided with a plurality of evenly arranged first elliptical scale-like grooves 14, and the first elliptical scale-like grooves 14 are provided on the outer surfaces of the ridges. The first sieve tube push rod 15 is provided inside the first hollow rod body 11, and the left end of the first sieve tube push rod 15 is flush with the left end of the second female joint 13, and the right end of the first sieve tube push rod 15 is provided on the left side of the right end of the first male joint 12, and the right end of the first sieve tube push rod 15 is provided with a first inner groove 16, and the left end of the first inner groove 16 is provided with a first male end support 17, and the right end of the first male end support 17 is provided along the radial direction of the first hollow rod body 11. A first positioning groove 18 is provided, and a first limiting groove 19 is provided at the right end of the first male end support 17 along the axial direction of the first screen tube push rod 15 to the left, a first spring seat 20 is provided at the left end of the first limiting groove 19, a first spring 21 is provided between the first spring seat 20 and the first male end support 17, a first outer convex head 22 corresponding to the first inner groove 16 is provided at the left end of the first screen tube push rod 15, a first mounting groove is provided on the first outer convex head 22, a first rubber sealing ring 23 is installed in the first mounting groove, a second limiting groove 24 is provided at the right end of the first outer convex head 22 along the axial direction, a first female end support 25 is provided at the right end of the second limiting groove 24, a second positioning groove 26 is provided at the right end of the first female end support 25 along the radial direction of the first hollow rod body 11, and a first elastic retaining ring 27 is provided at the left end of the first female end support 25.

[0041] The through-tube variable diameter reamer 3 comprises an outer rod body 28, a second male joint 29, a third female joint 30, a reaming blade 32, a hinge shaft 35, and a screenable inner tooth rod 36. The third female joint 30 is arranged at the left end of the outer rod body 28, and 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 through-tube variable diameter reamer is installed at the left end of the first guide tube four-sided 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 empty groove 31 and a second empty groove symmetrical to each other. A reaming blade 32 is respectively arranged in the first empty groove 31 and the second empty groove. The reaming blade 32 comprises a cutting piece 33 and a gear roller 34. The gear roller 34 is arranged at the left end of the cutting piece 33. The gear roller 34 is hinged to the outer rod body 28 through the hinge shaft 35. The inner gear rod 36 of the screenable tube is coaxially arranged inside the outer rod body 28, the left end of the inner gear rod 36 of the screenable tube is flush with the left end of the third female joint 30, the right end of the inner gear rod 36 of the screenable tube is arranged on the left side of the right end of the second male joint 29, and the right end of the inner gear rod 36 of the screenable tube is provided with a second inner groove 37 corresponding to the first outer convex head 22, the left end of the second inner groove 37 is provided with a symmetrical groove 38 along the outer surface of the inner gear rod 36 of the screenable tube, the left end of the groove 38 is provided with a gear table 39 corresponding to the gear roller 34 along the axial direction to the right, and the right end of the gear table 39 is provided with equidistantly distributed vents 40 on the surface of the groove 38 along the axial direction to the right, a limited displacement groove 41 is provided on the left side of the groove 38, a positioning plate 42 is provided on the right end of the limited displacement groove 41, and the positioning plate 42 is fixed to the inner surface of the outer rod body 28, and a second outer convex head 43 corresponding to the second inner groove 37 is provided on the left side of the limited displacement groove 41.

[0042] The axial length of the variable diameter reamer 3 is 300-400 mm, the first slot 31 and the second slot 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 32 is 150-200 mm, the angle between the reaming blade 32 in the first slot 31 and the reaming blade 32 in the second slot is ≤180°, and the diameter of the vent 40 is 4-6 mm. The radial length of the reaming blade 32 is equal to the radial length of the first empty slot 31 and the second empty slot. The cutting blades 33 of the two reaming blades 32 are distributed in the direction of rotation of the drill bit while cutting the coal and rock. The cutting blade 33 is a boss-shaped structure as a whole. The hinge shaft 35 connects the gear roller 34 and the outer rod body 28 together. The inner gear rod 36 of the screen tube is coaxially arranged with the outer rod body 28. The maximum outer diameter and the minimum inner diameter of the inner gear rod 36 of the screen tube are the same as those of the first screen tube push rod 15. The length of the limiting groove 41 is the distance that the inner gear rod 36 of the screen tube moves from the initial state to the 180° state of the two reaming blades 32. The positioning plate 42 is a ring-cylindrical structure formed by removing a small cylinder along the axis of a cylinder, and the positioning plate 42 is fixed to the inner surface of the outer rod body 28.

[0043] The second conduit four-sided grooved drill rod 4 comprises a second hollow rod body 44, a third male joint 45, a fourth female joint 46, a second screen-tube push rod 48, a second rubber sealing ring 56, a second elastic retaining 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 the third male joint 45 corresponds to the third female joint 30. The second concave grooved drill rod 4 is connected to the left end of the through-tube variable diameter reamer 3 through the third male joint 45 and the third female joint 30. Four second concave arc portions in the left and right directions are circumferentially arranged at equal intervals on the outer surface of the second hollow rod body 44, so that the second hollow rod body 44 forms a four-convex ridge structure. A pair of symmetrical convex ridges on the outer surface of the second hollow rod body 44 are axially and evenly spaced. A plurality of second elliptical scale-like grooves 47 are arranged; the number of the second elliptical scale-like grooves 47 is 10, and the direction of the major axis of the ellipse is 30° with the axial direction of the rod body, and the maximum depth of the grooves 47 is 2 mm; The second screen tube push rod 48 is coaxially arranged inside the second hollow rod body 44, the left end of the second screen tube push rod 48 is flush with the left end of the fourth female joint 46, the right end of the second screen tube push rod 48 is located on the left side of the right end of the third male joint 45, the right end of the second screen tube push rod 48 is provided with a third inner groove 49, the third inner groove 49 is provided with a second male end support 50 in sequence, the right end of the second male end support 50 is provided with a third positioning groove 51 along 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 to the left along the axial direction of the second screen tube push rod 48, the second spring seat 53 is provided at the left end of the third limiting groove 52, and the second spring 54 is provided between the second spring seat 53 and the second male end support 50; A third outer convex head 55 corresponding to the third inner groove 49 is arranged at the left end of the second screen tube push rod 48, a second installation groove is arranged axially on the third outer convex head 55, a second rubber sealing ring 56 is installed in the second installation groove, a fourth limiting groove 57 is arranged axially at the right end of the third outer convex head 55, a second female end support 58 is arranged at the right end of the fourth limiting groove 57, a right fourth positioning groove 59 is arranged radially along the second hollow rod body 44 at the right end of the second female end support 58, and a second elastic retaining ring 60 is arranged at the left end of the second female end support 58.

[0044] The diameter of the first guide tube four-sided grooved drill rod 2 is 80-100 mm, and 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 tube push rod 15 is 50-55 mm, and the inner diameter is 35-38 mm. A gap of 5-20 mm is provided between the outer surface of the first screen tube 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 retaining ring 27 is 2-5 mm, and the radial outer edge of the first elastic retaining ring 27 is tangent to the radial outer edge of the first female end support 25. The first male end support 17 is a hollow cylindrical outer surface with three convex ridge structures distributed at equal intervals around the circumference. Specifically, the first male end support 17 includes a hollow cylinder 61 and three convex ridges 62 arranged on the cylinder. The radial minimum diameter of the first positioning groove 18 is greater than the maximum outer diameter of the first screen tube 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 cylinder, the size of which is the same as the hollow cylindrical part of the first male end support 17, the axial length of the first male end support 17 is 15mm, the shape of the first female end support 25 is the same as 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 tube 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 15mm; The diameter of the second guide tube four-sided grooved drill rod 4 is 80-100mm, and the length is 1000-1500mm. The length of the second hollow rod body 44 is 800-1000mm. The maximum outer diameter of the second screen tube push rod 48 is 50-55mm, and the inner diameter is 35-38mm. A gap of 5-20mm is provided between the outer surface of the second screen tube 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 15-20mm, the length of the second female end support 58 is 15-20mm, the axial length of the second elastic retaining ring 60 is 2-5mm, and the radial outer edge of the second elastic retaining ring 60 is tangent to the radial outer edge of the second female end support 58. The first elastic retaining ring 27 and the second elastic retaining ring 60 have the same shape, both of which are horseshoe-shaped, and the male joint and the female joint are connected by a threaded connection or a clamp type connection.

[0045] The second male end support 50 is a hollow cylindrical body with three convex ridge structures distributed at equal intervals on the outer surface of the circumference. The radial minimum diameter of the third positioning groove 51 is greater than the maximum outer diameter of the second screen tube push rod 48. The radial maximum diameter of the third positioning groove 51 is equal to the radial maximum diameter of the second male end support 50. The radial minimum diameter of the third limiting groove 52 is equal to the radial minimum diameter of the second male end support 50. The second spring seat 53 is a cored cylinder with the same size as the hollow cylindrical part of the second male end support 50. The second male end support 50 The axial length is 15 mm, the shape of the second female end support 58 is the same as that of the second male end support 50, the radial minimum diameter of the second female end support 58 is less than or equal to the radial minimum diameter of the second male end support 50, the radial minimum diameter of the fourth limiting groove 57 is equal to the radial minimum diameter of the second female end support 58, the radial minimum diameter of the fourth positioning groove 59 is greater than the maximum outer diameter of the second screen tube push rod 48, the radial maximum diameter of the fourth positioning groove 59 is equal to the radial maximum diameter of the second female end support 58, and the axial length of the second female end support 58 is 15 mm; The present application realizes layered hole expansion and permeability improvement by controlling the opening and closing angles of the reamer blades through the movable push rod and spring structure arranged inside the drill tool. At the same time, the screenable structure of the push rod makes it possible to directly lower the screen without withdrawing the drill tool and then screening after the hole expansion and permeability improvement is completed, thereby realizing simultaneous permeability improvement and hole protection, which can effectively reduce the complexity of process operations, improve the gas extraction efficiency of low-permeability coal seams, reduce the gas risk in the coal mining process, and ensure the safety of miners and production efficiency.

[0046] To sum up, the present application has a scientific design and a reasonable structure, and can realize the coordinated operation of permeability enhancement and hole protection, thereby improving the gas extraction efficiency of low-permeability coal seams, reducing gas risks, and promoting safe production in coal mines.

[0047] Embodiment 2 like Figure 19-21 As shown, the difference from Example 1 is that the elliptical scale-like grooves on the outer surfaces of the first hollow rod body 11 and the second hollow rod body 44 in the first guide tube four-sided grooved drill rod 2 and the second guide tube four-sided grooved drill rod 4 in Example 1 are changed from one pair of symmetrical side distribution in Example 1 to two pairs of symmetrical side distribution, and other structural parameters are consistent with Example 1, and the working principle is the same as Example 1.

[0048] Embodiment 3 The drilling method is implemented based on the above-mentioned low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool, and comprises the following steps: (1) Assembling drilling tools for layered hole expansion, permeability enhancement and hole protection in low-permeability coal seams; (2) The assembled low-permeability coal seam layered hole expansion and permeability enhancement drilling tool is installed on a crawler drilling rig, and the intelligent hole expansion operating table is connected to the second screen tube push rod 48 at the rear end of the drilling tool, and drilling construction is carried out.

[0049] The specific operation process of step (1) is as follows: the large diameter drill bit 1 is installed on the right end of the first guide tube four-sided grooved drill rod 2 through the first female joint 9 and the first male joint 12, the through-tube variable diameter reamer 3 is installed on the left end of the first guide tube four-sided grooved drill rod 2 through the second male joint 29 and the second female joint 13, and the second guide tube four-sided grooved drill rod 4 is installed on the left end of the through-tube 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 hole expansion and permeability protection drilling tool.

[0050] The specific operation process of step (2) is as follows: the drill tool is installed on the crawler drilling rig through the fourth male joint and the fourth female joint 46 matched with the fourth male joint arranged on the crawler drilling rig, and the intelligent hole expansion operating table is connected at the second screen tube push rod 48 at the rear end of the drill tool. After starting the drilling rig, the drill tool starts drilling under the drive of the drilling rig. During the drilling process, the intelligent hole expansion operating table is equipped with the second screen tube push rod 48 and the first screen tube push rod 15 to perform precise automatic layered hole expansion and permeability enhancement to increase gas permeability and fluidity. In combination with the built-in screen tube structure of the drilling tool, it is not only convenient for the lower screen tube, which is beneficial to protecting the borehole and improving the gas extraction efficiency, but also beneficial to overcoming the problems of low operating efficiency and low safety caused by the passive situation of separation of the penetration permeability enhancement process from the lower screen tube.

[0051] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool, characterized by: The utility model comprises a large-diameter drill bit, a first guide tube four-sided grooved drill rod, a through-tube variable-diameter reamer and a second guide tube four-sided grooved drill rod, the right end of the first guide tube four-sided grooved drill rod is connected to the left end of the large-diameter drill bit, the through-tube variable-diameter reamer is arranged between the first guide tube four-sided grooved drill rod and the second guide tube four-sided grooved drill rod, the right end of the through-tube variable-diameter reamer is connected to the left end of the first guide tube four-sided grooved drill rod, the right end of the second guide tube four-sided grooved drill rod is connected to the left end of the through-tube variable-diameter reamer, the large-diameter drill bit, the first guide tube four-sided grooved drill rod, the through-tube variable-diameter reamer and the second guide tube four-sided grooved drill rod are coaxially arranged and are axially provided with mutually connected pipes; when drilling, the left end of the second guide tube four-sided grooved drill rod is connected to the drilling machine, and drilling is performed through the large-diameter drill bit.

2. The low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool according to claim 1 is characterized by: 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 rounded to form an arc surface, and the cutting blades are evenly arranged on the arc surface along the circumference. A baffle is arranged at the right end of the connecting rod body, and one end of the baffle is hinged to the right end of the connecting rod body. A first female joint is arranged at the left end of the connecting rod body. A plurality of first cylindrical diamond composite sheets of the same size are arranged at the right end of the cutting blade, and a plurality of second cylindrical diamond composite sheets of the same size are arranged on the lower surface of the baffle.

3. The low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool according to claim 2 is characterized by: The first guide tube four-sided groove drill rod comprises a first hollow rod body, a first male joint, a second female joint, a first screen tube 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 retaining ring. 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 tube four-sided groove drill rod through the first female joint and the first male joint. The outer surface of the first hollow rod body is provided with four first concave arc portions in the left and right directions at equal intervals along the circumference, so that the first hollow rod body forms a four-convex ridge structure, and a pair of symmetrical convex ridges on the outer surface of the first hollow rod body are provided with a plurality of evenly arranged first elliptical scale grooves, the first screen tube type push rod is arranged inside the first hollow rod body, the left end of the first screen tube type push rod is flush with the left end of the second female joint, the right end of the first screen tube 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 tube type push rod is provided with a first inner groove, the left end of the first inner groove is provided with a first male end support, and the right end of the first male end support is provided with a first fixed groove along the radial direction of the first hollow rod body. A first limiting groove is arranged on the right end of the first male end support along the axial direction of the first screen tube push rod to the left, a first spring seat is arranged on the left end of the first limiting groove, a first spring is arranged between the first spring seat and the first male end support, a first outer convex head corresponding to the first inner groove is arranged on the left end of the first screen tube push rod, a first installation groove is arranged on the first outer convex head, a first rubber sealing ring is installed in the first installation groove, a second limiting groove is arranged on the right end of the first outer convex head along the axial direction, a first female end support is arranged on the right end of the second limiting groove, a second positioning groove is arranged on the right end of the first female end support along the radial direction of the first hollow rod body, and a first elastic retaining ring is arranged on the left end of the first female end support.

4. The low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool according to claim 3 is characterized by: The through-pipe variable diameter reamer comprises an outer rod body, a second male joint, a third female joint, a reaming blade, a hinge shaft, and a screenable inner toothed rod, wherein 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 tube four-sided grooved drill rod through the second male joint and the second female joint, the outer rod body is provided with a first empty slot and a second empty slot symmetrical to each other, a reaming blade is respectively arranged in the first empty slot and the second empty slot, the reaming blade comprises a cutting blade and a gear roller, the gear roller is arranged at the left end of the cutting blade, and the gear roller is hinged to the outer rod body through the hinge shaft; The inner gear rod of the screenable tube is coaxially arranged inside the outer rod body, the left end of the inner gear rod of the screenable tube is flush with the left end of the third female joint, the right end of the inner gear rod of the screenable tube is arranged on the left side of the right end of the second male joint, and the right end of the inner gear rod of the screenable tube is provided with a second inner groove corresponding to the first outer convex head, and the left end of the second inner groove is provided with a symmetrical groove along the outer surface of the inner gear rod of the screenable tube, and a gear table corresponding to the gear roller is axially arranged to the right at the left end of the groove, and vent holes distributed at equal intervals are arranged on the groove surface at the right end of the gear table axially to the right, a limited displacement groove is provided on the left side of the groove, a positioning plate is provided on the right end of the limited displacement groove, and the positioning plate is fixed to the inner surface of the outer rod body, and a second outer convex head corresponding to the second inner groove is provided on the left side of the limited displacement groove.

5. The low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool according to claim 4 is characterized by: The axial length of the variable diameter reamer for through-tube is 300-400mm, the first empty slot and the second empty slot have the same size, the radial length is 30-40mm, the axial length is 200-250mm, the axial length of the reaming blade is 150-200mm, the angle between the reaming blade in the first empty slot and the reaming blade in the second empty slot is ≤180°, and the diameter of the vent is 4-6mm.

6. The low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool according to claim 5 is characterized by: The second guide tube four-sided grooved drill rod comprises a second hollow rod body, a third male joint, a fourth female joint, a second screen tube push rod, a second rubber sealing ring, a second elastic retaining ring, a second spring seat, and a second spring. The third male joint is arranged at the right end of the second hollow rod body, and the third male joint corresponds to the third female joint. The second guide tube four-sided grooved drill rod is connected to the left end of the through-tube variable diameter reamer through the third male joint and the third female joint. Four second concave arc portions in the left and right directions are evenly spaced and arranged along the circumference on the outer surface of the second hollow rod body, so that the second hollow rod body forms a four-convex ridge structure. A pair of symmetrical ridges on the outer surface of the second hollow rod body are evenly spaced along the axial direction. A plurality of second elliptical scale-shaped grooves are arranged; The second screen tube push rod is coaxially arranged inside the second hollow rod body, the left end of the second screen tube push rod is flush with the left end of the fourth female joint, the right end of the second screen tube push rod is located on the left side of the right end of the third male joint, the right end of the second screen tube push rod is provided with a third inner groove, the third inner groove sequence section is provided with a second male end support, the right end of the second male end support is provided with a third positioning groove along 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 to the left along the axial direction of the second screen tube push rod, the second spring seat is provided at the left end of the third limiting groove, and the second spring is provided between the second spring seat and the second male end support; A third outer convex head corresponding to the third inner groove is arranged at the left end of the second screen tube push rod, a second installation groove is arranged axially on the upper side of the third outer convex head, a second rubber sealing ring is installed in the second installation groove, a fourth limiting groove is arranged axially on the right end of the third outer convex head, a second female end support is arranged at the right end of the fourth limiting groove, a right fourth positioning groove is arranged radially along the second hollow rod body at the right end of the second female end support, and a second elastic retaining ring is arranged at the left end of the second female end support.

7. The low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool according to claim 6 is characterized by: The diameter of the first guide tube four-sided 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 tube 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 tube 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 retaining ring is 2-5 mm, and the radial outer edge of the first elastic retaining ring is tangent to the radial outer edge of the first female end support; The diameter of the second guide tube four-sided grooved drill rod is 80-100mm, the length is 1000-1500mm, the length of the second hollow rod body is 800-1000mm, the maximum outer diameter of the second screen tube push rod is 50-55mm, the inner diameter is 35-38mm, and a gap of 5-20mm is provided between the outer surface of the second screen tube push rod and the inner surface of the second hollow rod body. The axial length of the second male end support is 15-20mm, the length of the second female end support is 15-20mm, the axial length of the second elastic retaining ring is 2-5mm, the radial outer edge of the second elastic retaining ring is tangent to the radial outer edge of the second female end support, and the first elastic retaining ring and the second elastic retaining ring have the same shape, both are horseshoe-shaped.

8. A drilling method, implemented based on the low-permeability coal seam layered hole expansion, permeability enhancement and hole protection drilling tool as claimed in any one of claims 1 to 7, characterized in that: The steps include: (1) Assembling drilling tools for layered hole expansion, permeability enhancement and hole protection in low-permeability coal seams; (2) The assembled low-permeability coal seam layered hole expansion and permeability protection drilling tool is installed on the crawler drilling rig, and the intelligent hole expansion operating table is connected to the second screen tube push rod at the rear end of the drilling tool to carry out drilling construction.

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

10. The drilling method according to claim 8, characterized in that: The specific operation process of step (2) is as follows: the drill bit is installed on the crawler drilling rig through the fourth male joint and the fourth female joint matched with the fourth male joint provided on the crawler drilling rig, and the intelligent hole expansion operating table is connected to the second screen tube push rod at the tail end of the drill bit. After starting the drilling rig, the drill bit starts drilling under the drive of the drilling rig. During the drilling process, the intelligent hole expansion operating table is equipped with the second screen tube push rod and the first screen tube push rod to perform accurate and automatic layered hole expansion and permeability enhancement.

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