Pressure relief and permeability increase device for deep soft coal seam
By combining hollow drill rods and high-pressure sealing, cavity-making, and slotting mechanisms, the problem of simultaneous cavity-making and slotting after drilling in deep, soft coal seams has been solved, enabling synchronous operation during the drilling process, reducing costs, and improving coal seam permeability.
Patent Information
- Application Number
- CN202511586568.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-01
- Publication Date
- 2026-02-24
AI Technical Summary
In existing technologies, it is impossible to simultaneously perform hole-making and slotting operations after drilling in deep, soft coal seams, which increases operating costs.
The design employs a combination of hollow drill rod, connecting pipe A, outer shell, connecting pipe B, and limiting spring. It forms a borehole channel through low-pressure medium drilling and utilizes a high-pressure sealing mechanism and a cavity-making and slotting mechanism to achieve simultaneous cavity-making and slotting operations in the borehole channel.
It enables the removal of slag in low-pressure media and the creation of cavities and slots in high-pressure media during the drilling process, reducing coal seam stress, increasing permeability, and improving extraction efficiency.
Smart Images
Figure CN121556789A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of coal seam decompression and permeability enhancement technology, and more specifically, to a device for decompression and permeability enhancement in deep, soft coal seams. Background Technology
[0002] Deep, soft coal seams are prone to gas outbursts and low extraction efficiency due to their low strength, poor permeability, and high gas content. Pressure relief and permeability enhancement technology is a core solution to these problems. Essentially, it uses physical or chemical methods to alter the coal structure, reduce stress levels, and increase the fracture network to improve seam permeability, creating safer conditions for gas extraction or coal seam mining. Currently, the most widely used pressure relief and permeability enhancement technologies are high-pressure water jet fracturing and abrasive gas jet fracturing.
[0003] For example, the patent with patent number "CN118757091B" discloses "a mechanical-hydraulic combined cavity-making and slotting pressure relief and permeability enhancement device and method, the device includes a drill bit part, a cavity-making part and a slotting part, the drill bit part, the cavity-making part and the slotting part are fixedly installed in sequence...", this patent can quickly switch between drilling, cavity-making and slotting by adjusting different water pressures, and the operation is simple.
[0004] The aforementioned mechanical-hydraulic combined cavity-making and slotting pressure relief permeation enhancement device can quickly switch between three core functions—drilling, hole enlargement (cavity making), and slotting—by adjusting a single variable of water pressure. However, since the cavity-making and slotting functions of the device rely on different water pressure gradients, the device cannot simultaneously perform cavity-making and slotting operations in the borehole channel after drilling, thereby increasing operating costs. Summary of the Invention
[0005] This invention provides a pressure relief and permeability enhancement device for deep, soft coal seams, solving the technical problem in related technologies where cavity creation and slotting operations cannot be carried out simultaneously after drilling, thus increasing operating costs.
[0006] This invention provides a pressure relief and permeability enhancement device for deep, soft coal seams, comprising a hollow drill rod and a drill bit that can enter the borehole channel;
[0007] It also includes a connecting pipe A, threaded to the end of the hollow drill rod, with a piston sleeve fixedly connected to the end of the connecting pipe A away from the hollow drill rod; a connecting pipe B, threaded to the end of the drill bit, with an outer shell slidably sleeved outside the piston sleeve fixedly connected to the end of the connecting pipe B away from the drill bit; a piston column extending into the piston sleeve fixedly connected inside the connecting pipe B; a medium channel opened inside the piston column; a limiting spring fixedly connected between the piston sleeve and the outer shell; a high-pressure sealing mechanism located inside the connecting pipe A, which seals the medium channel through high-pressure medium; and a cavity-creating and slotting mechanism located on the piston sleeve, which creates a cavity and slots in the drilling channel through high-pressure medium.
[0008] Preferably, the inner diameter of one end of the connecting pipe A is the same as the inner diameter of the hollow drill rod, and the inner diameter of the other end of the connecting pipe A is the same as the inner diameter of the piston sleeve.
[0009] Preferably, the outer diameter of the piston rod is adapted to the inner diameter of the piston sleeve.
[0010] Preferably, the end of the piston rod away from the connecting tube A extends to the inside of the drill bit, and the piston rod and the connecting tube B are fixedly connected by a sealing sleeve.
[0011] Preferably, the end of the medium channel away from the connecting pipe B is tapered.
[0012] Preferably, the limiting spring is located inside the outer casing and sleeved on the outside of the piston rod.
[0013] Preferably, the high-pressure sealing mechanism includes a cross fixedly connected inside the connecting pipe A, a connecting rod fixedly connected to one end of the cross near the connecting pipe B, and a sealing cone extending into the medium channel fixedly connected to the other end of the connecting rod away from the cross.
[0014] Preferably, the piston sleeve has a circumferentially oriented storage groove on its outer side, and the cavity-making and slit-cutting mechanism includes a cavity-making arm rotatably connected inside the storage groove. The cavity-making arm has cavity-making serrations on the side near the storage groove, and a spring plate fixed inside the storage groove is provided on the side of the cavity-making arm.
[0015] Preferably, the piston sleeve has an inner through groove circumferentially formed on its inner side, and the cavity-making and slit-cutting mechanism includes a hollow box circumferentially embedded inside the piston sleeve. Each hollow box has a connecting pipe fixedly connected to the outside of the inner through groove. Each adjacent hollow box has a hollow rod fixedly connected to the inside of a receiving groove. The hollow rod has an opening on its outside. The cavity-making arm rotates in a sealed manner outside the hollow rod. The cavity-making arm has a cavity communicating with the opening inside, and a slit-cutting nozzle communicating with the cavity is installed on the outside of the cavity-making arm.
[0016] The beneficial effects of this invention are as follows:
[0017] 1. In this invention, the hollow drill rod, connecting pipe A, outer shell, and connecting pipe B are "self-contained" under the constraint of the limiting spring and the abutment of the coal seam. By starting the drilling machine and introducing a low-pressure medium into the interior of the hollow drill rod, a borehole channel can be formed. At the same time, the low-pressure medium enters the inside of the drill bit and finally discharges the coal slag from the gap between the borehole channel and the device as the drill bit moves through the hole, thus ensuring a smooth drilling process.
[0018] 2. This invention employs a combination of a high-pressure sealing mechanism and a cavity-creating and slotting mechanism. The drilling rig drives the entire device to rotate and exit the borehole channel, while high-pressure medium is introduced into the hollow drill rod, completely sealing the medium channel. Simultaneously, the circumferentially distributed cavity-creating arms unfold, which can create and enlarge cavities in the soft coal seam. The high-pressure medium is ejected from the slotting nozzle, performing high-pressure jet slotting on the soft coal seam around the borehole channel, forming a fracture network inside the coal seam, reducing the stress of the coal seam (pressure relief), and increasing the permeability of the coal seam (permeability enhancement).
[0019] In summary, during the process of rotating into the borehole channel, the present invention can use a low-pressure medium (water or gas) to perform slag removal operations, and during the process of rotating out of the borehole channel, it can use a high-pressure medium (water or gas) to simultaneously perform cavity creation and slotting operations in the borehole channel. The two operations can achieve pressure relief and permeability enhancement of deep soft coal seams. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the first state structure of the present invention;
[0021] Figure 2 for Figure 1 A schematic diagram of the internal cross-sectional structure;
[0022] Figure 3 for Figure 2 Enlarged view of the structure at point A in the image;
[0023] Figure 4 This is a schematic diagram of the second state structure of the present invention;
[0024] Figure 5 for Figure 4 A schematic diagram of the internal cross-sectional structure;
[0025] Figure 6 for Figure 5 Enlarged view of the structure at point B in the image;
[0026] Figure 7 This is a schematic diagram of the hollow box structure in this invention.
[0027] In the diagram: 10. Hollow drill rod; 20. Drill bit; 30. Connecting pipe A; 31. Piston sleeve; 32. Receiving groove; 33. Inner through groove; 40. Connecting pipe B; 41. Outer shell; 42. Plug; 43. Medium channel; 44. Sealing sleeve; 50. Limiting spring; 60. High-pressure sealing mechanism; 61. Cross; 62. Connecting rod; 63. Sealing cone; 70. Cavity-making and slotting mechanism; 71. Cavity-making arm; 72. Spring plate; 73. Hollow box; 74. Connecting pipe; 75. Hollow rod; 76. Opening; 77. Cavity; 78. Slotting nozzle. Detailed Implementation
[0028] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.
[0029] like Figure 1 , Figure 2 , Figure 4 and Figure 5 As shown, this embodiment provides a deep, soft coal seam pressure relief and permeability enhancement device, including a hollow drill rod 10 and a drill bit 20 that can enter the borehole channel. The hollow drill rod 10 is connected to the drilling rig, and a medium can enter the hollow drill rod 10. The medium can be water or gas. The connection method between the hollow drill rod 10 and the drilling rig, as well as the method of the medium entering the hollow drill rod 10, are existing technologies and will not be described in detail here. It also includes a connecting pipe A30, which is threaded to the end of the hollow drill rod 10; a connecting pipe B40, which is threaded to the end of the drill bit 20; a limiting spring 50; a high-pressure sealing mechanism 60, which is disposed inside the connecting pipe A30; and a cavity-making and slotting mechanism 70, which is disposed on the piston sleeve 31.
[0030] Among them, such as Figure 2 and Figure 5 As shown, a piston sleeve 31 is fixedly connected to one end of the connecting pipe A30 away from the hollow drill rod 10. The inner diameter of one end of the connecting pipe A30 is the same as the inner diameter of the hollow drill rod 10, and the inner diameter of the other end of the connecting pipe A30 is the same as the inner diameter of the piston sleeve 31. This allows the medium entering the hollow drill rod 10 to smoothly pass through the connecting pipe A30 and enter the interior of the piston sleeve 31. A receiving groove 32 is provided on the outer circumferential side of the piston sleeve 31. The receiving groove 32 is used to receive the cavity-making arm 71 in the cavity-making and slit-cutting mechanism 70 described below. An inner through groove 33 is provided on the inner circumferential side of the piston sleeve 31. The inner through groove 33 is used to allow the high-pressure medium to enter the connecting pipe 74 in the cavity-making and slit-cutting mechanism 70 described below.
[0031] Among them, such as Figure 2 and Figure 5 As shown, the end of the connecting pipe B40 away from the drill bit 20 is fixedly connected to an outer shell 41 that is slidably sleeved on the outside of the piston sleeve 31. The outer diameter of the piston rod 42 is adapted to the inner diameter of the piston sleeve 31. The connection relationship between the piston rod 42 and the piston sleeve 31 is similar to the sliding relationship between the piston rod and the piston sleeve. The piston rod 42 extending into the piston sleeve 31 is fixedly connected inside the connecting pipe B40. The end of the piston rod 42 away from the connecting pipe A30 extends into the inside of the drill bit 20. The end of the piston rod 42 fits against the inside of the drill bit 20 to avoid affecting the slag discharge of the drill bit 20. The piston rod 42 and the connecting pipe B40 are fixedly connected by a sealing sleeve 44. A medium channel 43 is opened inside the piston rod 42. The end of the medium channel 43 away from the connecting pipe B40 is tapered. The end face of the piston rod 42 near the tapered end of the medium channel 43 is the force-bearing surface of the high-pressure medium.
[0032] Among them, such as Figure 2 and Figure 5 As shown, the limiting spring 50 is fixedly connected between the piston sleeve 31 and the outer sleeve 41. The limiting spring 50 is located inside the outer sleeve 41 and sleeved on the outside of the piston column 42. The limiting spring 50 is used to limit the position of the connecting pipe body B40, the outer sleeve 41, the piston column 42 and the drill bit 20, so as to ensure that the low-pressure medium can enter the interior of the drill bit 20 through the medium channel 43, thereby removing slag.
[0033] Among them, such as Figure 2 and Figure 5 As shown, the high-pressure sealing mechanism 60 can seal the medium channel 43 through the high-pressure medium. The high-pressure sealing mechanism 60 includes a cross 61 fixedly connected inside the connecting pipe body A30. A connecting rod 62 is fixedly connected to one end of the cross 61 near the connecting pipe body B40. A sealing cone 63 extending into the medium channel 43 is fixedly connected to the other end of the connecting rod 62 away from the cross 61. Under the maintenance of the limiting spring 50, the low-pressure medium in the hollow drill pipe 10 can enter the interior of the medium channel 43 through the cross 61, the connecting rod 62 and the sealing cone 63.
[0034] Among them, such as Figure 2 and Figure 5As shown, the cavity-making and slotting mechanism 70 can create cavities and slots in the borehole channel through a high-pressure medium. The cavity-making and slotting mechanism 70 includes a cavity-making arm 71 rotatably connected inside the receiving groove 32. The cavity-making arm 71 has cavity-making serrations on the side near the receiving groove 32. A spring plate 72 fixed inside the receiving groove 32 is provided on the side of the cavity-making arm 71. In the initial state, the cavity-making arm 71 is stored inside the receiving groove 32 through the outer shell 41 and squeezes the spring plate 72. When the drilling rig drives the device to advance and drill, under the maintenance of the limiting spring 50 and the contact of the coal seam, the outer shell 41 always abuts against the connecting pipe body A30. That is, when the drill bit 20 is drilling, the hollow drill rod 10, the connecting pipe body A30, the outer shell 41, and the connecting pipe body B40 form a whole and follow the drill bit 20 into the borehole channel.
[0035] like Figure 3 , Figure 6 and Figure 7 As shown, the cavity-making and slotting mechanism 70 includes a hollow box 73 circumferentially embedded inside the piston sleeve 31. A connecting pipe 74 located inside the inner through groove 33 is fixedly connected to the outer side of each hollow box 73. A hollow rod 75 located inside the receiving groove 32 is fixedly connected between adjacent hollow boxes 73. An opening 76 is provided on the outside of the hollow rod 75. A cavity 77 communicating with the opening 76 is provided inside the cavity-making arm 71. A slotting nozzle 78 communicating with the cavity 77 is installed on the outside of the cavity-making arm 71. When the high-pressure medium enters the connecting pipe body A30, it can push the force-bearing surface of the piston column 42, cooperating with the sealing cone 63 to seal the medium channel 43 and open the circumferential cavity-making arm 71, allowing the high-pressure medium to enter the cavity-making arm 71 and be ejected through the slotting nozzle 78. The entire device can then be withdrawn to achieve cavity-making and slotting of the drilling channel.
[0036] The specific working principle of this implementation can be divided into two operation stages. The first operation stage involves the drilling rig driving the entire device to rotate and enter the coal seam to form a borehole channel. At the same time, low-pressure medium is used to complete the slag removal during the drilling process. The second operation stage involves the drilling rig driving the entire device to rotate and exit the borehole channel. At the same time, high-pressure medium is used to seal the medium channel 43, drive the circumferentially distributed cavity-making arms 71 to unfold and spray high-pressure medium, and perform "mechanical cavity making + high-pressure cutting" on the soft coal seam around the borehole channel, thereby achieving pressure relief and permeability enhancement of the coal seam.
[0037] The specific working process of the first stage of operation: Due to the maintenance of the limiting spring 50, the outer shell 41 is pressed against the connecting pipe A30, and the circumferentially distributed cavity-making arms 71 are squeezed into the receiving groove 32 (compressing the spring plate 72), so that the hollow drill rod 10, connecting pipe A30, outer shell 41, connecting pipe B40 and drill bit 20 can be "self-contained" to ensure the smoothness of subsequent drilling operations. Then, the drilling rig is connected to the hollow drill rod 10, the drilling rig is started and a low-pressure medium (water) is introduced into the hollow drill rod 10. (or gas), at this time, the hollow drill rod 10, connecting pipe A30, outer shell 41, and connecting pipe B40 are "self-contained" under the constraint of the limiting spring 50 and the abutment of the coal seam. They enter the coal seam synchronously with the drill bit 20 to form a drilling channel. At the same time, the low-pressure medium passes through the connecting pipe A30, the gap of the cross 61, the connecting rod 62, the sealing cone 63, and the medium channel 43 in sequence to enter the inside of the drill bit 20. Finally, with the drilling action of the drill bit 20, the coal slag is discharged from the gap between the drilling channel and the device to ensure a smooth drilling process.
[0038] During the process of the device as a whole rotating with the drilling rig to form a drilling channel, the hollow drill rod 10, connecting pipe A30, outer shell 41, and connecting pipe B40 are "self-contained" under the constraint of the limiting spring 50 and the abutment of the coal seam, and enter the coal seam synchronously with the drill bit 20. At the same time, the low-pressure medium can discharge coal slag from the gap between the drilling channel and the device as the drill bit 20 drills.
[0039] The specific working process of the second phase of the operation is as follows: After the borehole channel reaches the preset depth, the drilling rig is started to drive the entire device to rotate and exit the borehole channel. High-pressure medium (water or gas) is then introduced into the hollow drill rod 10. After the high-pressure medium enters the connecting pipe A30, it directly acts on the "force-bearing surface" of the piston rod 42 near the converging end of the medium channel 43 (this end surface is the main action surface of the high-pressure medium). The thrust of the high-pressure medium can overcome the limiting support force of the limiting spring 50, pushing the piston rod 42 to move away from the connecting pipe A30, and simultaneously driving the connecting pipe B40 and the outer casing. 41. The drill bit 20 moves together with the piston rod 42. During this process, the sealing cone 63 is fixed to the cross 61 of the connecting pipe A30 by the connecting rod 62. When the medium channel 43 moves with the piston rod 42 to fit tightly against the outer wall of the sealing cone 63, the medium channel 43 is completely blocked. At the same time, the cavity-making arm 71 squeezed by the outer shell 41 loses its restraint. The spring plate 72 storing elastic potential energy rebounds quickly, pushing the cavity-making arm 71 to unfold. The piston rod 42 no longer blocks the connecting pipe 74. The high-pressure medium can enter the hollow box 73, the hollow rod 75 and the cavity 77 through the connecting pipe 74.
[0040] During the process of the entire device rotating and exiting the borehole channel along with the drilling rig, the cavitation saw teeth on the extended cavity-creating arm 71 can contact the coal seam on the inner wall of the borehole channel to create cavities and expand the soft coal seam. At the same time, high-pressure medium can be ejected from the cutting nozzle 78 to perform high-pressure jet cutting on the soft coal seam around the borehole channel, forming a fracture network inside the coal seam, reducing the stress of the coal seam (pressure relief), and increasing the permeability of the coal seam (permeability enhancement).
[0041] The embodiments of the present invention have been described above, but the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the embodiments described above, all of which are within the protection scope of the embodiments described above.
Claims
1. A device for depressurizing and enhancing permeability in deep, soft coal seams, comprising a hollow drill rod (10) and a drill bit (20) capable of entering a borehole channel, characterized in that, Also includes: Connecting pipe A (30) is threaded to the end of hollow drill rod (10), and piston sleeve (31) is fixedly connected to the end of connecting pipe A (30) away from hollow drill rod (10). A connecting tube B (40) is threaded to the end of the drill bit (20). The end of the connecting tube B (40) away from the drill bit (20) is fixedly connected to an outer shell (41) that is slidably sleeved on the outside of the piston sleeve (31). A piston column (42) extending into the piston sleeve (31) is fixedly connected inside the connecting tube B (40). A medium channel (43) is opened inside the piston column (42). A limiting spring (50) is fixedly connected between the piston sleeve (31) and the outer shell (41); The high-pressure sealing mechanism (60) is installed inside the connecting pipe body A (30) and seals the medium channel (43) through the high-pressure medium; The cavity-making and slotting mechanism (70) is set on the piston sleeve (31) and uses high-pressure medium to make cavity-making and slotting in the borehole channel.
2. The deep soft coal seam pressure relief and permeability enhancement device according to claim 1, characterized in that, The inner diameter of one end of the connecting tube A (30) is the same as the inner diameter of the hollow drill rod (10), and the inner diameter of the other end of the connecting tube A (30) is the same as the inner diameter of the piston sleeve (31).
3. The deep soft coal seam pressure relief and permeability enhancement device according to claim 2, characterized in that, The outer diameter of the piston rod (42) is adapted to the inner diameter of the piston sleeve (31).
4. The deep soft coal seam pressure relief and permeability enhancement device according to claim 3, characterized in that, The piston rod (42) extends to the inside of the drill bit (20) at one end away from the connecting tube A (30), and the piston rod (42) and the connecting tube B (40) are fixedly connected by a sealing sleeve (44).
5. A deep, soft coal seam pressure relief and permeability enhancement device according to claim 4, characterized in that, The end of the medium channel (43) away from the connecting pipe body B (40) is constricted.
6. The deep soft coal seam pressure relief and permeability enhancement device according to claim 5, characterized in that, The limiting spring (50) is located inside the outer shell (41) and sleeved on the outside of the piston rod (42).
7. A deep, soft coal seam pressure relief and permeability enhancement device according to claim 6, characterized in that, The high-pressure sealing mechanism (60) includes a cross (61) fixedly connected inside the connecting pipe body A (30), and a connecting rod (62) fixedly connected to one end of the cross (61) near the connecting pipe body B (40), and a sealing cone (63) extending into the medium channel (43) fixedly connected to the other end of the connecting rod (62) away from the cross (61).
8. A deep, soft coal seam pressure relief and permeability enhancement device according to claim 7, characterized in that, The piston sleeve (31) has a circumferentially circumferentially open receiving groove (32). The cavity-making and slit-cutting mechanism (70) includes a cavity-making arm (71) rotatably connected inside the receiving groove (32). The cavity-making arm (71) has cavity-making serrations on the side near the receiving groove (32). The side of the cavity-making arm (71) is provided with a spring plate (72) fixed inside the receiving groove (32).
9. A deep, soft coal seam pressure relief and permeability enhancement device according to claim 8, characterized in that, The piston sleeve (31) has an inner through groove (33) circumferentially opened on the inner side. The cavity-making and slit-cutting mechanism (70) includes a hollow box (73) circumferentially embedded inside the piston sleeve (31). The hollow box (73) is fixedly connected to a connecting pipe (74) located inside the inner through groove (33) on the outer side. The adjacent hollow boxes (73) are fixedly connected to a hollow rod (75) located inside the receiving groove (32). The hollow rod (75) has an opening (76) on the outside. The cavity-making arm (71) is sealed and rotates outside the hollow rod (75). The cavity-making arm (71) has a cavity (77) communicating with the opening (76) inside. The cavity-making arm (71) has a slit-cutting nozzle (78) communicating with the cavity (77) installed on the outside of the cavity-making arm (71).