Pulse fracturing device, coal mine underground drilling multi-stage pulse fracturing system and method

Abstract

The application discloses a kind of pulse fracturing device, coal mine underground drilling multistage pulse fracturing system and method.Pulse fracturing device includes cylinder, baffle assembly and elastic element, cylinder has inner cavity, the side wall of cylinder is equipped with pulse hole group, pulse hole group includes multiple pulse holes;Baffle assembly is arranged in cylinder, baffle assembly is movable relative to cylinder along the axis of cylinder, to block the pulse hole in pulse hole group, or make the outside of cylinder through at least part of pulse hole in pulse hole group with inner cavity communication;Elastic element is arranged between baffle assembly and cylinder, the fluid that flows into cylinder from the second end of cylinder can push baffle assembly to move and make elastic element elastically deformed.The embodiment of the application can be compressed by fluid to push baffle assembly and move, thereby opening at least part of pulse hole in pulse hole group, thereby realizing that pulse hole discharges pulse water flow, the generation position of pulse wave corresponds to construction section, attenuation is small, and pulse fracturing effect is better.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic fracturing technology, specifically relating to a pulse fracturing device, a multi-stage pulse fracturing system and method for underground coal mine drilling. Background Technology

[0002] Some mining areas have thick, hard coal seams that are difficult to mine. Above the coal seam are multiple layers of thick, hard rock, ranging from 10 to 30 meters in height. This rock mass is dense, high-strength, and has numerous thick, hard roof layers. During coal seam mining, the hard coal mass is difficult to break, easily causing damage to equipment such as coal mining machines and tunneling machines. The thick, hard roof can easily form large areas of overhang, accumulating elastic energy and potentially leading to sudden fracture and dynamic disasters.

[0003] In related technologies, hydraulic fracturing is used to create fractures, but this results in a single main fracture inside the coal and rock mass, which damages the integrity of the coal and rock mass but cannot effectively reduce the size of the coal and rock mass. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a pulse fracturing device that can provide pulsed fluid for borehole fracturing operations.

[0006] The embodiments of the present invention propose a multi-stage pulse fracturing system for underground coal mine drilling.

[0007] The embodiments of the present invention propose a multi-stage pulse fracturing method for underground coal mine drilling.

[0008] The pulse fracturing device of this invention includes:

[0009] A cylindrical body having an inner cavity, a first end of the cylindrical body being sealed, a second end of the cylindrical body being open, and a pulse hole group being provided on the side wall of the cylindrical body, the pulse hole group including multiple pulse holes;

[0010] A baffle assembly is disposed within the cylinder and is movable relative to the cylinder along the axial direction of the cylinder to block the pulse holes in the pulse hole group or to allow the inner cavity to communicate with the outside of the cylinder through at least a portion of the pulse holes in the pulse hole group.

[0011] An elastic element is disposed between the baffle assembly and the cylinder. Fluid flowing into the cylinder from the second end of the cylinder can push the baffle assembly to move and cause the elastic element to undergo elastic deformation.

[0012] In this embodiment of the invention, the baffle assembly can be compressed and moved by fluid, thereby opening at least some of the pulse holes in the pulse hole group, thereby realizing the discharge of pulsed water flow from the pulse holes. Periodic stress waves can be formed in the borehole, improving the pulse effect. In this embodiment, the pulse wave generation position corresponds to the construction section, with small attenuation and better pulse fracturing effect.

[0013] In some embodiments, a plurality of pulse holes in the pulse hole group are arranged at intervals along the circumference of the cylinder;

[0014] There are multiple baffle assemblies, which are arranged sequentially along the circumference of the cylinder. Each baffle assembly has multiple through holes arranged at intervals along the axial direction of the cylinder. Each baffle assembly and the pulse hole are arranged in a one-to-one correspondence. As the baffle assembly moves, the through holes and the pulse holes can communicate with each other. At least one elastic element is provided between each baffle assembly and the cylinder.

[0015] In some embodiments, a guide member is further included, which is disposed within the cylinder and divides at least a portion of the cylinder into a plurality of sliding cavities. The plurality of sliding cavities are arranged circumferentially along the cylinder, and a plurality of baffle assemblies are disposed in the plurality of sliding cavities in a corresponding manner.

[0016] In some embodiments, the system further includes a guide post disposed within the cylinder and adjacent to a first end of the cylinder. The guide component includes an end plate and a plurality of guide plates. The length direction of the guide plates is parallel to the axial direction of the cylinder. The end plate is sleeved on the guide post. The plurality of guide plates are spaced apart along the circumferential direction of the guide post and connected to the end plate. The sliding cavity is defined between two adjacent guide plates, the inner wall of the cylinder, and the outer wall of the guide post.

[0017] The baffle assembly includes a support plate and a baffle. The support plate is slidably disposed in the sliding cavity, and the baffle is connected to the support plate and fits against the inner wall of the cylinder.

[0018] In some embodiments, the elastic element is a spring, and the elastic coefficient of a portion of the plurality of elastic elements is different from that of another portion.

[0019] In some embodiments, the cylinder includes a first cylinder and a second cylinder, the first cylinder and the second cylinder are coaxially arranged and connected together, the end of the first cylinder away from the second cylinder is sealed, the end of the second cylinder away from the first cylinder is open, the pulse hole group is disposed on the second cylinder, and the elastic element is disposed in the first cylinder.

[0020] In some embodiments, the first cylinder has a first flange at one end adjacent to the second cylinder, and the second cylinder has a second flange at one end adjacent to the first cylinder. Both the first flange and the second flange are provided with a plurality of through holes. The first flange and the second flange are connected by fasteners provided in some of the through holes, and the other part of the through holes is used to pass through the water injection pipe of the sealing device.

[0021] This invention also discloses a multi-stage pulse fracturing system for underground coal mine drilling, including...

[0022] A fracturing tube, wherein the first end of the fracturing tube has a plug and the second end of the fracturing tube is a fluid inlet end;

[0023] A pulse fracturing device, wherein the pulse fracturing device is as described in any of the above embodiments, the pulse fracturing device is connected to the fracturing tube and disposed adjacent to the first end of the fracturing tube, and the inner cavity of the cylinder is in communication with the liquid inlet end of the fracturing tube.

[0024] In some embodiments, the device further includes a perforator and a water injection pipe. The perforator is disposed on the outside of the fracturing tube, and the perforator is provided on the fracturing tubes at both ends of the axial direction of the pulse fracturing device. The water injection pipe is disposed on the outside of the fracturing tube and communicates with the inner cavity of the perforator; and / or,

[0025] The inner cavity of the fracturing tube between the first end of the cylinder and the plug defines an independent installation cavity and a detection cavity. The detection cavity is connected to the outside of the fracturing tube. The installation cavity is equipped with a detection component, a data storage unit, and a power supply unit. The detection end of the detection component extends into the detection cavity. The data storage unit is used to store the data information of the detection component. The power supply unit is used to supply power to the data storage unit and the detection component.

[0026] This invention discloses a multi-stage pulse fracturing method for underground coal mine drilling, which utilizes the multi-stage pulse fracturing system described in any of the above-mentioned embodiments for pulse fracturing operations. The multi-stage pulse fracturing method for underground coal mine drilling includes:

[0027] Directional drilling was carried out inside the tunnel;

[0028] Connect the plug, fracturing tube, pulse fracturing device and sealing device together to form a pulse fracturing tube assembly, and perform water injection test on the pulse fracturing device and the sealing device;

[0029] After the water injection test is completed, the pulse fracturing tubing assembly is placed into the directional borehole until the preset construction section is reached, and water is injected into the sealing device to achieve setting and sealing.

[0030] Water is injected into the fracturing pipe, and the water flowing into the pulse fracturing device pushes the baffle component to move, so that at least some of the pulse holes in the pulse hole group are connected to the fracturing pipe, so that water flows into the borehole to carry out pulse fracturing operations.

[0031] After the pulse fracturing of the previous preset construction section is completed, water is drained from the sealing device, and the pulse fracturing tube assembly is moved to the next preset construction section. Water is injected into the sealing device to achieve setting and sealing, and the previous step is repeated to carry out the pulse fracturing operation in the construction section.

[0032] Repeat the previous step until the pulse fracturing operation is completed in all construction sections. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a multi-stage pulse fracturing system for underground coal mine drilling according to an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the connection between the elastic element and the baffle assembly according to an embodiment of the present invention.

[0035] Figure 3 yes Figure 2 A top-down view.

[0036] Figure 4 yes Figure 2 A side view diagram.

[0037] Figure 5 This is a three-dimensional schematic diagram of the guide component according to an embodiment of the present invention.

[0038] Figure 6 This is a front view schematic diagram of the guide component according to an embodiment of the present invention.

[0039] Figure 7 This is a front view schematic diagram of the first cylindrical body according to an embodiment of the present invention.

[0040] Figure 8 This is a side view of the first cylindrical body according to an embodiment of the present invention.

[0041] Figure 9 This is a front view schematic diagram of the second cylinder according to an embodiment of the present invention.

[0042] Figure 10 This is a side view of the second cylinder according to an embodiment of the present invention.

[0043] Figure label:

[0044] 100. Multi-stage pulse fracturing system for underground coal mine drilling;

[0045] 1. Cylinder body; 11. First cylinder body; 12. Second cylinder body; 13. First flange; 14. Second flange; 15. Guide post; 16. Pulse hole;

[0046] 2. Baffle assembly; 21. Support plate; 22. Baffle; 23. Through hole;

[0047] 3. Elastic components;

[0048] 4. Guide components; 41. End plate; 42. Guide plate;

[0049] 5. Fracturing tubing; 51. Main section; 52. Inner end section; 53. Installation cavity; 54. Inspection cavity;

[0050] 61. Plug; 62. Sealing device; 63. Water injection pipe;

[0051] 71. Power supply unit; 72. Data storage unit; 73. Detection component; 731. Detection terminal. Detailed Implementation

[0052] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0053] The pulse fracturing apparatus of the present invention is described below according to an embodiment of the present invention.

[0054] See Figures 1 to 10 The pulse fracturing device of this invention includes a cylinder 1, a baffle assembly 2, and an elastic element 3.

[0055] The cylinder 1 is generally cylindrical and has an inner cavity. The first end of the cylinder 1 is sealed, while the second end is open and connected to the fracturing tube 5, allowing fluid to flow into the inner cavity of the cylinder 1. A set of pulse holes 16, comprising multiple pulse holes 16, is provided on the side wall of the cylinder 1. The pulse holes 16 connect the inner cavity of the cylinder 1 to the external space. When the pulse holes 16 are not blocked, fluid can flow from the inner cavity of the cylinder 1 into the external space of the cylinder 1.

[0056] The baffle assembly 2 is disposed inside the cylinder 1. The baffle assembly 2 is movable relative to the cylinder 1 along the axial direction of the cylinder 1 to block the pulse holes 16 in the pulse hole group 16, or to make the inner cavity communicate with the outside of the cylinder 1 through at least a portion of the pulse holes 16 in the pulse hole group 16. The elastic element 3 is disposed between the baffle assembly 2 and the cylinder 1. The fluid flowing into the cylinder 1 from the second end of the cylinder 1 can push the baffle assembly 2 to move and cause the elastic element 3 to undergo elastic deformation.

[0057] When water is injected into the fracturing tube 5, the water flows into the inner cavity of the cylinder 1 and pushes the baffle assembly 2 to move inside the cylinder 1. At the same time, the elastic element 3 is compressed, and at least some of the pulse holes 16 in the group of pulse holes 16 blocked by the baffle assembly 2 are exposed, thereby allowing the fluid inside the cylinder 1 to flow to the external space of the cylinder 1 through the exposed pulse holes 16.

[0058] When connected to the fracturing pipe 5 for borehole fracturing operations, the initial stage is the pressure-holding pulse fracturing stage, and the later stage is the fracture propagation pulse fracturing stage.

[0059] During the pre-fracture pressure-pressurization pulse fracturing stage, the fluid pressure inside the borehole continuously rises. The fluid inside the fracturing tube 5 continuously squeezes the baffle assembly 2. As the baffle assembly 2 moves, more pulse holes 16 are exposed, and fluid flows to the outside of the cylinder 1 through more pulse holes 16, thus realizing the pulse generation structure. During the fracture propagation pulse fracturing stage, the fluid pressure inside the borehole fluctuates less. The fluid inside the fracturing tube 5 repeatedly squeezes the baffle assembly 2, and different pulse holes 16 repeatedly open and close to form the pulse generation structure.

[0060] In this embodiment of the invention, the baffle assembly 2 can be compressed and moved by the fluid, thereby opening at least some of the pulse holes 16 in the pulse hole 16 group, thereby realizing the discharge of pulse water flow from the pulse holes 16. Periodic stress waves can be formed in the borehole, improving the pulse effect. In this embodiment, the pulse wave generation position corresponds to the construction section, with small attenuation and better pulse fracturing effect.

[0061] In some embodiments, multiple pulse holes 16 in the pulse hole group 16 are arranged at intervals along the circumference of the cylinder 1. There are multiple baffle assemblies 2, which are arranged sequentially along the circumference of the cylinder 1. Each baffle assembly 2 is provided with multiple through holes 23 arranged at intervals along the axial direction of the cylinder 1. The baffle assembly 2 and the pulse holes 16 are arranged in a one-to-one correspondence. As the baffle assembly 2 moves, the through holes 23 and the pulse holes 16 can communicate. At least one elastic element 3 is provided between each baffle assembly 2 and the cylinder 1.

[0062] The elastic element 3 can be a columnar spring, and the elastic coefficient of some of the multiple sets of elastic elements 3 is different from that of other parts.

[0063] For example, there are 5 baffle assemblies 2 and 5 pulse holes 16 groups. A set of elastic elements 3 is provided between each baffle assembly 2 and the pulse hole 16 groups. Each set of elastic elements 3 includes 2 to 5 elastic elements 3. The elastic coefficients of the elastic elements 3 in different groups are different. Or, the elastic coefficient of the elastic elements 3 in one set of elastic elements 3 is the smallest. The elastic coefficients of the elastic elements 3 in two sets of elastic elements 3 are the same and the elastic coefficient is the largest. The elastic coefficients of the elastic elements 3 in the other two sets of elastic elements 3 are the same and the size is between the largest elastic coefficient and the smallest elastic coefficient.

[0064] During the pressure-pressurizing pulse fracturing stage before the fracture initiation, the fluid pressure inside the borehole continuously rises, and the fluid inside the fracturing tube 5 continuously squeezes the elastic elements 3 with different elastic coefficients. First, it squeezes and moves the elastic element 3 with the smaller elastic coefficient and moves the corresponding baffle assembly 2. The multiple through holes 23 on the baffle assembly 2 that are spaced at a certain distance are L1, L2...Ln respectively. The through holes 23 and the pulse holes 16 on the cylinder 1 open and close alternately to form a pulse generation structure.

[0065] As the fluid pressure inside the fracturing tube 5 continues to rise, when the fluid pressure compresses the elastic element 3 with a larger elastic coefficient, the corresponding baffle assembly 2 begins to move. At this time, a new pulse hole 16 can be opened. Under the action of the elastic elements 3 with different elastic coefficients, a multi-stage pulse generation structure can be formed.

[0066] During the fracture propagation pulse fracturing stage, the fluid pressure inside the borehole fluctuates less. The fluid inside the fracturing tube 5 reciprocates to squeeze the elastic elements 3 with different elastic coefficients. The through holes 23 and pulse holes 16 on different baffle assemblies 2 reciprocate to open and close, forming a multi-stage pulse generation structure. The large-volume fluid inside the fracturing tube 5 enters the fracturing space of the borehole through different pulse generation structures, forming a large-volume multi-stage pulse fluid.

[0067] In some embodiments, the pulse fracturing apparatus further includes a guide member 4 disposed inside the cylinder 1. The guide member 4 divides at least a portion of the cylinder 1 into multiple sliding cavities. The multiple sliding cavities are arranged along the circumference of the cylinder 1, and multiple baffle assemblies 2 are disposed in the multiple sliding cavities in a one-to-one correspondence.

[0068] The guide component 4 can guide the baffle assembly 2 to move in a specific direction, preventing the baffle assembly 2 from shifting or jamming, and improving the overall stability and smoothness of movement. The guide component 4 can be a separate component and assembled into the cylinder 1, or it can be welded to the cylinder 1 or fixedly connected to it by bolts or other connecting parts.

[0069] In this embodiment, the length of the sliding cavity extends parallel to the axial direction of the cylinder 1, and the multiple sliding cavities are relatively independent of each other. The multiple baffle assemblies 2 operate relatively independently, and adjacent baffle assemblies 2 do not affect each other when moving.

[0070] In some embodiments, the cylinder 1 has a guide post 15 at its center, which is disposed adjacent to the first end of the cylinder 1. The guide component 4 includes an end plate 41 and a plurality of guide plates 42. The length direction of the guide plates 42 is parallel to the axial direction of the cylinder 1. The end plate 41 is sleeved on the guide post 15. The plurality of guide plates 42 are connected to the end plate 41 along the circumferential direction of the guide post 15. The side edges of the guide plates 42 abut against the guide post 15. A sliding cavity is defined between two adjacent guide plates 42, the inner wall of the cylinder 1, and the outer wall of the guide post 15. The width direction of the guide plates 42 may be parallel to the radial direction of the cylinder 1, thereby the sliding cavity defined between two adjacent guide plates 42 is generally fan-shaped. The width dimension of the sliding cavity gradually decreases from the end near the inner wall of the cylinder 1 to the end near the guide post 15, thus forming a generally constricted structure.

[0071] In this embodiment, the guide post 15 is only provided in the middle of a section of the cylinder 1 near the first end.

[0072] The baffle assembly 2 includes a support plate 21 and a baffle 22. The support plate 21 is slidably disposed in the sliding cavity, and the baffle 22 is connected to the support plate 21. The baffle 22 abuts against the inner wall of the cylinder 1 to block the corresponding pulse holes 16. The support plate 21 is flat, and two of its opposite sidewalls are arc-shaped. One of the arc-shaped sidewalls abuts against the inner wall of the cylinder 1, and the other arc-shaped sidewall abuts against the outer wall of the guide post 15. The other two opposite sidewalls of the support plate 21 abut against two adjacent guide plates 42, thereby allowing the support plate 21 to move in a specific direction within the sliding cavity.

[0073] Baffle 22 fits against the inner wall of cylinder 1. In the initial state, the through hole 23 on baffle 22 is misaligned with the pulse hole 16 on cylinder 1, allowing the solid part of baffle 22 to block the pulse hole 16. When water is injected into cylinder 1, the water flow pushes support plate 21 and baffle 22 to move. When the through hole 23 and pulse hole 16 are aligned, the water in cylinder 1 can flow out through the through hole 23 and pulse hole 16. As the water pressure further increases, support plate 21 and baffle 22 continue to move, alternately blocking and opening the pulse hole 16, forming a pulse generation structure.

[0074] The elastic coefficients of the elastic elements 3 corresponding to the multiple baffle assemblies 2 are different. Therefore, a multi-stage pulse generation structure can be formed between the multiple baffle assemblies 2 and the cylinder 1, improving the pulse effect and practicality. This ensures that during borehole fracturing operations, periodic pulsed fluid can be generated inside the borehole to impact the surface of the coal and rock mass, generating pulse waves inside the coal and rock mass and effectively forming a complex fracture network. When there is no water in the borehole, the pulsed jet intermittently impacts the borehole wall, causing cyclic deformation of the borehole wall through compression and tension, leading to fatigue damage of the borehole wall and reducing the rock strength. When the borehole is filled with water, through pulse pressurization, the pulsed fluid impacts the fluid inside the borehole to form periodic stress waves. The stress waves are reflected at the fracture tip to form reflected waves. The superposition of the reflected waves and the incident waves causes the pressure at the fracture tip to rise.

[0075] In this embodiment, the pulsed fluid can be directly placed at the fracturing section. Since long-distance pipeline transportation is not required, pulse wave attenuation is avoided, thereby improving the effectiveness of the pulsed fluid. Compared to related technologies where pulsed fluid transportation causes pipeline vibration, leading to gaps between the sealing device 62 and the borehole wall and affecting sealing quality, the fracturing tube 5 in this embodiment has good stability, good sealing performance of the distributor, and relatively good fluid stability within the fracturing tube 5. Furthermore, it provides pulsed fluid with significant pressure changes inside the borehole, resulting in good fracture quality.

[0076] In some embodiments, the cylinder 1 includes a first cylinder 11 and a second cylinder 12, the first cylinder 11 and the second cylinder 12 are coaxially arranged and connected together, the end of the first cylinder 11 away from the second cylinder 12 is sealed, the end of the second cylinder 12 away from the first cylinder 11 is open, the pulse hole 16 is arranged on the second cylinder 12, and the elastic element 3 is arranged inside the first cylinder 11.

[0077] During assembly, the first cylinder 11 and the second cylinder 12 are coaxially connected together. In this embodiment, the guide component 4 and the guide post 15 are also located inside the first cylinder 11. The guide post 15 can be connected to the end of the first cylinder 11 away from the second cylinder 12, facilitating subsequent alignment and installation. Since the cylinder 1 needs to be connected to the fracturing tube 5 later, after the cylinder 1 is connected to the fracturing tube 5, it will divide the fracturing tube 5 into two sections, namely the main body section 51 and the inner end section 52. Therefore, in this embodiment, the first cylinder 11 can be connected to the inner end section 52 of the fracturing tube 5, and the second cylinder 12 can be connected to the main body section 51 of the fracturing tube 5. When the first cylinder 11 and the second cylinder 12 are connected together, the connection between the main body section 51 and the inner end section 52 can be realized, forming an integral structure.

[0078] Furthermore, the first cylinder 11 has a first flange 13 at one end adjacent to the second cylinder 12, and the second cylinder 12 has a second flange 14 at one end adjacent to the first cylinder 11. Both the first flange 13 and the second flange 14 have multiple through holes. The first flange 13 and the second flange 14 are connected by fasteners located in some of the through holes, while the other part of the through holes is used for the water injection pipe 63 of the sealing device 62 to pass through. In this embodiment, the first cylinder 11 and the second cylinder 12 are connected together by the first flange 13 and the second flange 14, resulting in good structural stability. Furthermore, some of the through holes on the first flange 13 and the second flange 14 can serve as directional holes for the water injection pipe 63 of the sealing device 62.

[0079] This invention also discloses a multi-stage pulse fracturing system 100 for underground coal mine drilling, including a fracturing pipe 5 and a pulse fracturing device. The first end of the fracturing pipe 5 has a plug 61, and the second end of the fracturing pipe 5 is a fluid inlet end.

[0080] The pulse fracturing device is as described in any of the above embodiments. The pulse fracturing device is connected to the fracturing tube 5 and disposed adjacent to the first end of the fracturing tube 5. The inner cavity of the cylinder 1 is connected to the fluid inlet end of the fracturing tube 5. The fracturing tube 5 includes a main body section 51 and an inner end section 52. The length of the inner end section 52 is relatively shorter than that of the main body section 51, and it is arranged adjacent to the bottom of the borehole drilled on the roadway wall. The main body section 51 is connected to a pumping device for pumping water into the cylinder 1 and allowing it to flow into the fracturing space of the borehole through the pulse orifice 16.

[0081] Furthermore, it also includes a sealing device 62 and a water injection pipe 63. The sealing device 62 is located on the outside of the fracturing pipe 5. The fracturing pipe 5 at both ends of the axial direction of the pulse fracturing device is equipped with a sealing device 62. The water injection pipe 63 is located on the outside of the fracturing pipe 5 and is connected to the inner cavity of the sealing device 62.

[0082] One of the sealing devices 62 can be installed on the inner end section 52 of the fracturing tube 5, and the other sealing device 62 can be installed at one end of the main body section 51 of the fracturing tube 5 adjacent to the pulse fracturing device. The two sealing devices 62 can define the fracturing space of the borehole, thereby enabling segmented fracturing of the borehole.

[0083] In this embodiment, the inner cavity of the fracturing tube 5 between the first end of the cylinder 1 and the plug 61 defines an independent installation cavity 53 and a detection cavity 54. The installation cavity 53 and the detection cavity 54 can be separated by a partition. The outer wall of the fracturing tube 5 corresponding to the detection cavity 54 is provided with a through hole. The detection cavity 54 is connected to the fracturing space outside the fracturing tube 5. The installation cavity 53 is provided with a detection component 73, a data storage unit 72, and a power supply unit 71. The detection end 731 of the detection component 73 extends into the detection cavity 54. The data storage unit 72 is used to store the data information of the detection component 73. The power supply unit 71 is used to supply power to the data storage unit 72 and the detection component 73.

[0084] The detection component 73 can be a pressure sensor, and the detection end 731 of the pressure sensor is a probe that extends from the mounting cavity 53 into the detection cavity 54. During pulse fracturing, the fluid pressure in the detection cavity 54 is the same as the fluid pressure in the fracturing space formed between the two sealing devices 62. Therefore, the pulse pressure can be obtained through the detection component 73 for data acquisition and monitoring, ensuring stability during the fracturing process. Monitoring fluid pressure changes during the fracturing stage, accurately obtaining pressure data at different fracturing stages, determining the stability of pulse fracturing, and laying the foundation for process optimization are all beneficial.

[0085] This invention discloses a multi-stage pulse fracturing method for underground coal mine drilling, which utilizes the multi-stage pulse fracturing system 100 described above for pulse fracturing operations. The multi-stage pulse fracturing method for underground coal mine drilling includes:

[0086] S101. Constructing directional boreholes within the roadway. By setting up drilling sites within the roadway, drilling equipment is used to construct long directional boreholes inside the coal and rock mass.

[0087] S102. Connect the plug 61, fracturing tube 5, pulse fracturing device, and perforator 62 together to form a pulse fracturing tube assembly, and perform a water injection test on the pulse fracturing device and perforator 62. The inner end section 52 of the fracturing tube 5 and the first cylinder 11, and the main body section 51 of the fracturing tube 5 and the second cylinder 12 can be connected together by threads, or the first cylinder 11 and the inner end section 52 can be manufactured as a non-removable integral structure, and the second cylinder 12 and the main body section 51 can also be manufactured as a non-removable integral structure.

[0088] During the water injection test, the water injection pipe 63 of the sealer 62 can be connected to the pump set first, and water can be injected into the sealer 62 to test the sealing performance of the sealer 62 and the water injection pipe 63. Then, the fracturing pipe 5 is connected to the pump set, and fluid is injected into the fracturing pipe 5 through a pressurized pump to test whether the movement of different elastic elements 3 and baffle assembly 2 is stable, ensuring that the baffle assembly 2 can form pulsed fluid as expected.

[0089] S103. After the water injection test is completed, the pulse fracturing tubing is placed into the directional borehole until the preset construction section is reached. Water is injected into the sealing device 62 to achieve setting and sealing. Initially, construction is carried out from the bottom section of the borehole. After each section is completed, the pulse fracturing tubing is pulled outward to carry out the construction of the next section until the fracturing operation of the entire directional borehole is completed.

[0090] S104. Water is injected into the fracturing pipe 5. The water flowing into the pulse fracturing device moves the pusher plate 22, causing at least some of the pulse holes 16 in the pulse hole group 16 to connect with the fracturing pipe 5, allowing water to flow into the borehole for pulse fracturing operations. During this process, as the pressure of the water flowing into the fracturing pipe 5 changes, the pulse fracturing device can generate multi-stage pulse fluid. The large pressure change of the pulse fluid results in good multi-stage pulse fracturing effect on the borehole and good fracture quality.

[0091] After the pump unit pipeline is connected to the fracturing pipe 5, the high-volume water injection pump is turned on. The high-volume fluid squeezes the baffle assembly 2 in the fracturing pipe 5. Each baffle assembly 2 has multiple through holes 23L1 to Ln spaced apart on the baffle 22. When the baffle assembly 2 moves, the different through holes 23 and the pulse holes 16 on the cylinder 1 open and close alternately to form a multi-stage pulse fluid generation structure. Since the multiple baffle assemblies 2 correspond to elastic elements 3 with different elastic coefficients, the contraction of different elastic elements 3 is different when the water pressure is different. The high-volume fluid inside the fracturing pipe 5 enters the borehole fracturing space through different multi-stage pulse generation structures to form a high-volume multi-stage pulse fluid, and pulse fracturing is performed inside the borehole.

[0092] S105. After the pulse fracturing of the previous preset construction section is completed, water is drained from the sealing device 62, and the pulse fracturing tube assembly is moved to the next preset construction section. Water is injected into the sealing device 62 to achieve setting and sealing, and the previous step (i.e. step S104) is repeated to carry out the pulse fracturing operation of the construction section.

[0093] S106. Repeat the previous step (i.e. step S105) until the pulse fracturing operation of all construction sections is completed.

[0094] This invention provides a pulse fracturing device that features a simple process, high construction efficiency, low labor intensity, and controlled formation of large-volume, multi-stage pulsed fluid in the borehole fracturing section. Using this device for pulse fracturing of coal and rock masses can create a complex network of fractures with high-quality fractures. The integrity of the fractured coal and rock mass is disrupted, and the fracture network has a wide distribution range, effectively reducing the block size of the coal and rock mass. This significantly improves the practicality and application effect of the product. It is particularly effective for fracturing dense, high-strength, and thick, hard roofs, effectively preventing large-area roof overhang, avoiding the accumulation of elastic energy, and preventing major dynamic disasters. Furthermore, it avoids equipment damage when using mining machines, tunneling machines, and other equipment during construction.

[0095] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0096] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0097] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0098] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0099] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0100] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A pulse fracturing device, characterized in that, include: A cylindrical body having an inner cavity, a first end of the cylindrical body being sealed, a second end of the cylindrical body being open, and a pulse hole group being provided on the side wall of the cylindrical body, the pulse hole group including multiple pulse holes; A baffle assembly is disposed within the cylinder and is movable relative to the cylinder along the axial direction of the cylinder to block the pulse holes in the pulse hole group or to allow the inner cavity to communicate with the outside of the cylinder through at least a portion of the pulse holes in the pulse hole group. An elastic element is provided between the baffle assembly and the cylinder, and fluid flowing into the cylinder from the second end of the cylinder can push the baffle assembly to move and cause the elastic element to undergo elastic deformation. The multiple pulse holes in the pulse hole group are arranged at intervals along the circumference of the cylinder; There are multiple baffle assemblies, which are arranged sequentially along the circumference of the cylinder. Each baffle assembly has multiple through holes arranged at intervals along the axial direction of the cylinder. Each baffle assembly and the pulse hole are arranged in a one-to-one correspondence. As the baffle assembly moves, the through holes and the pulse holes can communicate. At least one elastic element is provided between each baffle assembly and the cylinder. It also includes a guide component disposed inside the cylinder, the guide component dividing at least a portion of the cylinder into multiple sliding cavities, the multiple sliding cavities being arranged circumferentially along the cylinder, and the multiple baffle assemblies being disposed one-to-one in the multiple sliding cavities; It also includes a guide post, which is disposed inside the cylinder and adjacent to the first end of the cylinder. The guide component includes an end plate and a plurality of guide plates. The length direction of the guide plate is parallel to the axial direction of the cylinder. The end plate is sleeved on the guide post. The plurality of guide plates are spaced apart along the circumferential direction of the guide post and connected to the end plate. The sliding cavity is defined between two adjacent guide plates, the inner wall of the cylinder and the outer wall of the guide post. The baffle assembly includes a support plate and a baffle. The support plate is slidably disposed in the sliding cavity, and the baffle is connected to the support plate. The baffle is in close contact with the inner wall of the cylinder. The cylinder includes a first cylinder and a second cylinder, which are coaxially arranged and connected together. The end of the first cylinder away from the second cylinder is sealed, and the end of the second cylinder away from the first cylinder is open. The pulse hole group is provided on the second cylinder, and the elastic element is provided in the first cylinder. The first cylinder has a first flange at one end adjacent to the second cylinder, and the second cylinder has a second flange at one end adjacent to the first cylinder. Both the first flange and the second flange are provided with multiple through holes. The first flange and the second flange are connected by fasteners provided in some of the through holes, and the other part of the through holes is used to pass through the water injection pipe of the sealing device.

2. The pulse fracturing device according to claim 1, characterized in that, The elastic element is a spring, and the elastic coefficient of one part of the multiple elastic elements is different from the elastic coefficient of another part.

3. A multi-stage pulse fracturing system for underground coal mine drilling, characterized in that, include A fracturing tube, wherein the first end of the fracturing tube has a plug and the second end of the fracturing tube is a fluid inlet end; A pulse fracturing device, wherein the pulse fracturing device is as described in claim 1 or 2, the pulse fracturing device is connected to the fracturing tube and disposed adjacent to the first end of the fracturing tube, and the inner cavity of the cylinder is connected to the liquid inlet end of the fracturing tube.

4. The multi-stage pulse fracturing system for underground coal mine drilling according to claim 3, characterized in that, It also includes a perforator and a water injection pipe. The perforator is located on the outside of the fracturing tube, and the perforator is provided on the fracturing tube at both ends of the axial direction of the pulse fracturing device. The water injection pipe is located on the outside of the fracturing tube and communicates with the inner cavity of the perforator; and / or, The inner cavity of the fracturing tube between the first end of the cylinder and the plug defines an independent installation cavity and a detection cavity. The detection cavity is connected to the outside of the fracturing tube. The installation cavity is equipped with a detection component, a data storage unit, and a power supply unit. The detection end of the detection component extends into the detection cavity. The data storage unit is used to store the data information of the detection component. The power supply unit is used to supply power to the data storage unit and the detection component.

5. A multi-stage pulse fracturing method for underground coal mine drilling, characterized in that, Pulse fracturing is performed using the multi-stage pulse fracturing system for underground coal mine drilling as described in claim 3 or 4, wherein the multi-stage pulse fracturing method for underground coal mine drilling includes: Directional drilling was carried out inside the tunnel; Connect the plug, fracturing tube, pulse fracturing device and sealing device together to form a pulse fracturing tube assembly, and perform water injection test on the pulse fracturing device and the sealing device; After the water injection test is completed, the pulse fracturing tubing assembly is placed into the directional borehole until the preset construction section is reached, and water is injected into the sealing device to achieve setting and sealing. Water is injected into the fracturing pipe, and the water flowing into the pulse fracturing device pushes the baffle assembly to move, so that at least some of the pulse holes in the pulse hole group are connected to the fracturing pipe, so that water flows into the borehole to perform pulse fracturing operations. After the pulse fracturing of the previous preset construction section is completed, water is drained from the sealing device, and the pulse fracturing tube assembly is moved to the next preset construction section. Water is injected into the sealing device to achieve setting and sealing, and the previous step is repeated to carry out the pulse fracturing operation in the construction section. Repeat the previous step until the pulse fracturing operation is completed in all construction sections.

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