Segmented pulse fracturing method for underground coal-rock stratum directional long borehole, and equipment

Abstract

Segmented pulse fracturing method for coal-rock stratum directional long borehole in underground mine, and equipment. The method and the equipment can perform segmented pulse fracturing on a coal-rock stratum directional long borehole; by means of segmented fracturing, the shortcoming of unevenly distributed fractures present when a long borehole as a whole undergoes fracturing is effectively overcome, and the problem of fractures being externally dense and internally sparse is solved; at each segment, a coal rock mass is fatigued and damaged by means of high frequency pulsed water pressure, multidirectional hydraulic fractures not controlled by crustal stress are formed, primary fractures of the coal-rock stratum are activated, and a fracture network is formed; ultimately, the fracture networks of the segments extend and interconnect, and consequently uniformly distributed, intercommunicating dense fracture networks are formed in the directional long borehole. The present segmented pulse fracturing method causes a significant improvement in the fracturing effect of a long borehole; with the aid of a directional borehole drilling machine, the method is simple, work is convenient, the method is easy to perform, and safety and reliability are achieved.

Description

Directional long drilling segmented pulse fracturing method and equipment for coal and rock strata in mines Technical Field

[0001] The present invention relates to the field of coal rock fracturing in mines, in particular to a directional long-hole segmented pulse fracturing method and equipment for coal rock strata in mines, belonging to the technical field of mining engineering. Background Art

[0002] my country boasts significant coal reserves. In 2020, my country's coal production accounted for 50.7% of the world's total, ranking first globally. In recent years, the complex geological conditions of coal seams beneath coal mines have led to numerous disasters, including coal and gas outbursts and gas explosions, with complex mechanisms. Therefore, gas remains a significant constraint to safe coal mine production. To ensure safe and efficient mine production, conventional extraction methods should be improved. Artificial permeability enhancement methods should be used to create new fractures in coal seams, improve their fracture structure, and enhance their permeability.

[0003] Hydraulic fracturing, an important method for increasing reservoir permeability and improving fluid flow properties, is based on the principle of injecting fracturing fluid into the reservoir. This creates a network of fractures within a certain range, thereby increasing the reservoir's fracture connectivity and permeability, and achieving the goal of increasing permeability. Conventional fracturing uses a high-pressure, high-flow pump to inject fracturing fluid into the reservoir. Controlled by geostress, this process easily forms primary hydraulic fractures in the reservoir, resulting in localized stress concentrations and fewer branch fractures, making it difficult to form a complex fracture network. Compared to conventional fracturing, pulse fracturing uses pulsed, cyclical pumping. Under the action of high-frequency pulsed water pressure, it causes fatigue damage to the coal, creating hydraulic fractures in multiple directions that are not controlled by geostress. Simultaneously, the high-frequency pulsed water pressure impacts the coal, easily activating pre-existing fractures in the coal, allowing the hydraulic fractures to connect with natural fractures and forming a complex fracture network within the coal. The frequency and amplitude of the water pressure loading can alter the propagation morphology of the fracture network.

[0004] Staged fracturing technology is currently widely used in surface oil and gas reservoir fracturing to expand the scope of reservoir fracturing and enhance the effectiveness of fracturing to increase production. However, due to challenges such as limited working space, gas safety restrictions, hydraulic fracturing in long directional boreholes drilled from the bottom of the tunnel, and limitations in fracturing equipment and sealing processes, directional long-distance staged fracturing technology in mines is still in its infancy.

[0005] Conventional constant-displacement fracturing easily forms primary hydraulic fractures in the reservoir. Affected by geostress, hydraulic fractures are singular and poorly uniform, limiting the scope of coal seam reconstruction. Some areas may remain unfractured, resulting in high gas concentrations and low gas pressure gradients. Consequently, gas extraction efficiency in these areas is low. Therefore, pulse fracturing is required to create a uniform fracture network, avoid the formation of low gas pressure gradients, and thus improve gas extraction efficiency. Furthermore, the high-frequency pulsed water used in downhole directional long-bore segmented pulse fracturing can significantly damage sealing equipment, requiring a more sophisticated sealing process. Furthermore, interference between pulse fracturing intervals can occur, necessitating the determination of appropriate fracturing and sealing locations.

[0006] Conventional fracturing in underground coal mines primarily involves fracturing a straight borehole using conventional hydraulic drills with a constant pumping rate, with a maximum borehole length of less than 200 meters. The fracturing process involves manually installing sealers and high-pressure sealing strings, resulting in a limited range per single borehole and a large engineering effort.

[0007] Directional long-distance drilling refers to drilling that relies on a kilometer-long directional drilling rig underground in a coal mine, with controllable drilling direction and a length generally greater than 200 meters. The change in drilling direction and the increase in length pose challenges to conventional fracturing methods and equipment. In terms of fracturing methods, conventional constant-displacement fracturing of long-distance drilling suffers from uneven crack distribution throughout the entire section, resulting in blind spots in long-borehole fracturing transformation. Furthermore, the direction of crack expansion in conventional constant-displacement fracturing is controlled by the ground stress field, resulting in a small number of cracks in conventional constant-displacement fracturing. In terms of fracturing equipment, conventional rigid high-pressure sealing tubing for fracturing cannot adapt to the bending changes in the direction of directional long-distance drilling, and manual installation of sealers and high-pressure sealing tubing is impossible at long distances. Therefore, the uneven crack distribution and small number of cracks in conventional constant-displacement fracturing throughout the entire section are technical bottlenecks for directional long-hole fracturing in coal formations. Summary of the Invention

[0008] In order to overcome the above-mentioned deficiencies of existing methods and equipment, the present invention proposes a method and equipment for segmented pulse fracturing of directional long boreholes in mines. This method and equipment can perform pulse fracturing in segments in directional long boreholes in coal and rock formations. On the one hand, segmented fracturing effectively overcomes the disadvantage of uneven distribution of fracturing cracks due to overall fracturing of long boreholes, and solves the problem of "dense outside and sparse inside" cracks; at the same time, high-frequency pulse water pressure is used in each segment to cause fatigue damage to the coal and rock mass, forming multi-directional hydraulic fractures that are not controlled by ground stress, and activating the original fractures in the coal and rock formations to form a fracture network; finally, the pulse fracture network in each segment expands and penetrates, thereby forming a dense fracture network that is evenly distributed and interconnected in the directional long borehole. This technology significantly improves the fracturing effect of long boreholes. At the same time, with the help of directional drilling rigs, the method is simple, the construction is convenient, the operation is easy, and it is safe and reliable.

[0009] According to the different drilling construction locations and fracturing layers, corresponding processes have been formed, such as the directional long drilling segmented pulse fracturing process for the working face level tunnel along the layer, the directional long drilling segmented pulse fracturing process for the bottom pumping tunnel through the layer, the directional long drilling segmented pulse fracturing process for the soft coal seam roof, and the directional long drilling segmented pulse fracturing process for the hard roof.

[0010] The directional long drilling and segmented pulse fracturing process in the working face level tunnel is to construct a directional long borehole in the coal seam in the working face return air tunnel / transport tunnel of the relatively hard coal seam, and inject high-pressure pulse water into the long borehole through the pulse pump to perform segmented pulse fracturing on the coal seam; the directional long drilling and segmented pulse fracturing process in the bottom pumping tunnel is to construct a directional long borehole in the bottom pumping tunnel of the coal seam to the relatively hard coal seam, and inject high-pressure pulse water into the long borehole to perform segmented pulse fracturing on the coal seam to form a fracture network; when the coal seam is relatively soft, the hole collapse is more serious when drilling in the coal seam, and the fracturing The formed cracks will close quickly under closing stress. This can be achieved by constructing a directional long borehole in the roof and using large-displacement segmented pulse fracturing in the long borehole to make the fracturing cracks penetrate the coal seam, forming a connected crack network in the roof and the coal seam, namely the directional long borehole segmented pulse fracturing process for the roof of the soft coal seam; the directional long borehole segmented pulse fracturing process for the hard roof is to construct a directional long borehole in the return air lane / transport lane of the working face to the hard roof rock layer above the coal seam, and inject high-pressure pulse water into the long borehole through a pulse pump to perform segmented pulse fracturing on the hard rock layer.

[0011] A method for segmented pulse fracturing of directional long boreholes in coal rock formations in mines, comprising the following steps: S1. Designing a directional long borehole trajectory for the coal rock formation according to the target coal rock formation to be transformed and the drilling construction site, and constructing a directional long borehole to the target coal rock formation according to the designed trajectory by a directional drilling rig; S2. Determining the number of directional long borehole pulse hydraulic fracturing sections, segment lengths, and sealing positions of each fracturing interval according to the actual construction trajectory of the directional long borehole and the actual length in the target coal rock formation; S3. Before pulse hydraulic fracturing, using a directional drilling rig to sweep the constructed directional long borehole to remove debris in the hole; S4. After the sweeping is completed, withdraw the drill rod and drill bit, connect the sealing device and the high-pressure sealing pipe string, and use the directional drilling rig to send the high-pressure sealing pipe string and the sealing device to the first fracturing position; S5. Separate the directional drilling rig from the high-pressure sealing drill rod, and connect the high-pressure sealing drill rod, the high-pressure hose, and the pulse hydraulic fracturing pump; S6. Open the pulse pump outlet valve, close the pressure relief valve, and then open the pulse fracturing pump to perform the first stage of pulse fracturing: S7. After the first stage of fracturing is completed, turn off the pump to release the pressure, and use the directional drilling rig to retreat the high-pressure sealed drill pipe and the sealing device to the second stage of designed sealing position; S8. Connect the high-pressure sealed directional drill pipe adapter between the high-pressure hose and the high-pressure sealed directional drill pipe, and turn on the pulse fracturing pump to perform the second stage of fracturing: S9. Repeat S5-S8 until the segmented pulse fracturing of the entire borehole is completed; S10. Use the directional drilling rig to withdraw all high-pressure sealed drill pipes and sealing devices in the borehole; S11. Observe and evaluate the effect of pulse hydraulic fracturing according to the purpose of the segmented pulse fracturing construction.

[0012] In step S1, the drilling construction site is the return air lane / transport lane of the working face, and the target layer to be transformed is the coal seam. A directional drilling rig is used to construct long directional holes along the coal seam in the return air lane / transport lane of the working face to perform segmented pulse fracturing to transform the coal seam.

[0013] In step S1, the drilling construction site is the coal seam bottom extraction lane, and the target layer to be transformed is the coal seam. A directional drill is used to construct a long directional drill hole through the coal seam in the bottom extraction lane to perform segmented pulse fracturing to transform the coal seam.

[0014] In step S1, the drilling construction site is the return air lane / transport lane of the working face, and the target layer to be transformed is the soft coal seam. Since the coal seam is soft, the hole collapse is serious when drilling in the soft coal seam, the drilling effect is poor, and the cracks formed by fracturing will close quickly under the closing stress. A directional drilling rig is used to construct a through-layer directional long drill hole in the return air lane / transport lane of the working face toward the coal seam roof for segmented pulse fracturing, so that the roof fracturing cracks penetrate the soft coal seam, forming a connected crack network in the roof and the soft coal seam, thereby realizing the fracturing transformation of the soft coal seam.

[0015] To ensure that the roof pulse fracturing cracks penetrate into the soft coal seam, the vertical distance between the directional long drill hole in the roof and the soft coal seam should not exceed 5m, and during pulse fracturing, the fracturing time should be extended by 20 to 40 minutes compared with fracturing in the soft coal seam.

[0016] In step S1, the drilling construction site is the return air lane / transport lane of the working face, and the target layer to be transformed is the roof rock layer. A directional drilling rig is used to construct a long directional drill hole through the return air lane / transport lane of the working face toward the roof rock layer to perform segmented pulse fracturing to transform the roof rock layer.

[0017] In step S11, the effect of pulse hydraulic fracturing is observed and evaluated according to the purpose of the segmented pulse fracturing construction. Specifically, the purpose of the segmented pulse fracturing construction in step S11 includes permeability enhancement of low-permeability coal seams, weakening of hard top coal, and weakening and reducing impact of coal rock strength; The segmented pulse fracturing permeability enhancement by directional long drilling of low-permeability coal seams is to form a uniform fracture network in the coal seam by the segmented pulse fracturing method, increase the fracture area, and increase the number of fluid migration channels, thereby improving the reservoir permeability; The segmented pulse fracturing weakening by directional long drilling of hard top coal is to form a uniform fracture network in the coal seam by the segmented pulse fracturing method in the comprehensive working face, fully cut the coal body, reduce the strength of the coal body, and thereby reduce the size of the top coal falling; The segmented pulse fracturing reducing impact by directional long drilling of coal rock formations is to construct a long borehole in the coal seam or rock formation to reach a high stress area, perform segmented pulse fracturing in the high stress area, weaken the coal rock formation, transfer the high stress, and reduce the probability of coal rock formation impact hazards, thereby ensuring safe and efficient production of the mine; The observation of the permeability enhancement effect of the directional long-hole segmented pulse fracturing in low-permeability coal seams includes: the concentration, flow rate and scalar amount of the borehole gas extraction after the segmented pulse fracturing; if the above-mentioned borehole gas extraction concentration, flow rate and scalar amount parameters after the segmented pulse fracturing are increased by more than 50% compared with those before construction, it is judged that the effect is good; if they increase by less than 20%, it is judged that the effect is not good; the observation of the weakening effect of the directional long-hole segmented pulse fracturing in hard top coal includes: the top coal caving fragmentation after the segmented pulse fracturing; if the top coal caving fragmentation parameter after the segmented pulse fracturing is increased by more than 50% compared with before construction, it is judged that the effect is good; if it increases by less than 20%, it is judged that the effect is not good; the observation of the impact reduction effect of the directional long-hole segmented pulse fracturing in coal rock formations includes: the impact energy events and energy amplitude of the coal rock formations after the segmented pulse fracturing; if the above-mentioned impact energy events and energy amplitude of the coal rock formations after the segmented pulse fracturing are reduced by more than 40% compared with those before construction, it is judged that the effect is good; if they are reduced by less than 20%, it is judged that the effect is poor.

[0018] The present invention further discloses the segmented pulse fracturing equipment used in the segmented pulse fracturing method for directional long drilling of coal and rock formations in mines, comprising: a pulse pump, a pulse pump outlet valve, a high-pressure hose, a high-pressure sealed directional drill pipe joint, a high-pressure sealed directional drill pipe, a segmented pulse fracturing sealing device and a drill bit connected end to end in sequence, wherein the pulse pump outlet valve, a high-pressure hose pressure relief valve, a tee, a flow sensor and a pressure sensor are arranged in sequence on the high-pressure hose along the direction of fluid flow; the flow sensor is connected to a measuring and controlling instrument via a flow measuring line to monitor the fluid flow in real time, which is displayed and recorded in real time by the measuring and controlling instrument; the pressure sensor is connected to the measuring and controlling instrument via a pressure measuring line to monitor the fluid pressure in real time, which is displayed and recorded in real time by the measuring and controlling instrument; The segmented pulse fracturing sealing device includes a kilometer-long directional drilling rig, multiple first high-pressure sealed directional drill pipes, sealer joints, near-hole end sealers, near-hole end adapters, multiple second high-pressure sealed directional drill pipes, near-hole bottom end adapters, near-hole bottom end sealer joints, near-hole bottom end sealers and high-pressure sealed semi-closed directional drill pipes connected in sequence; the high-pressure sealed semi-closed directional drill pipe is connected between the near-hole bottom end sealer and the drill bit, is blocked at the near-hole bottom end, and is open at the near-hole end.

[0019] The high-pressure hose pressure relief valve is a high-pressure wear-resistant ball valve; the high-pressure sealed directional drill pipe joint, high-pressure sealed directional drill pipe, near-hole end sealer joint, near-hole end sealer, near-hole end adapter, near-hole end adapter, near-hole bottom end sealer joint and near-hole bottom end sealer are hollow high-pressure resistant rods; the high-pressure hose and the high-pressure sealed directional drill pipe joint are connected by a U-shaped card; the high-pressure sealed directional drill pipe joint and the high-pressure sealed directional drill pipe, between the high-pressure sealed directional drill pipe and the sealer joint, between the adapter and the sealer, and between the high-pressure sealed directional drill pipe and the high-pressure sealed directional drill pipe are all threaded connections.

[0020] The connection of the sealing device and the high-pressure sealed drill pipe described in step S4 refers to connecting and sealing the drill bit, the high-pressure sealed semi-closed directional drill pipe, the bottom end sealer near the hole, the bottom end sealer joint near the hole, the bottom end adapter near the hole, multiple high-pressure sealed directional drill pipes, the near-hole end adapter, the near-hole end sealer, the near-hole end sealer joint and multiple high-pressure sealed directional drill pipes through threads, and then sending them into the borehole in sequence using a directional drilling rig.

[0021] Connecting the high-pressure sealed drill pipe, high-pressure hose and pulse hydraulic fracturing pump in step S5 means connecting the high-pressure sealed directional drill pipe at the outermost end of the orifice to the high-pressure sealed directional drill pipe joint, high-pressure hose, flow sensor, fracturing sensor, high-pressure hose pressure relief valve, pulse pump outlet valve and pulse pump in sequence, and the high-pressure sealed directional drill pipe joint and the high-pressure hose are connected by a U-shaped card; the flow sensor is connected to the measuring and control instrument through a flow measuring line, and the pressure sensor is connected to the measuring and control instrument through a pressure measuring line.

[0022] The pulse hydraulic fracturing process described in step S6 is to inject pulse water through a pulse pump, and the pulse water passes through a high-pressure hose, a pulse pump outlet valve, a tee, a flow sensor, a pressure sensor, a high-pressure sealed directional drill pipe joint, multiple first high-pressure sealed directional drill pipes, a near-hole end sealer joint, a near-hole end sealer, a near-hole end sealer joint, multiple second high-pressure sealed directional drill pipes, a near-hole bottom end adapter, a near-hole bottom end sealer joint, a near-hole bottom end sealer, and a high-pressure sealed semi-closed directional drill pipe. As the high-pressure water is injected, the near-hole end sealer and the near-hole bottom end sealer expand, forming a closed space between the two sealers. When the pulse water pressure in the pipeline exceeds the pressure of the one-way valve on the near-hole end adapter and the near-hole bottom end adapter, the pulse water enters the closed area between the near-hole end sealer and the near-hole bottom end sealer. The pulse water acts on the borehole wall to form a damaged crack zone. As the pulse water is continuously injected, the damaged crack zone expands and extends to form a pulse water pressure crack network. Beneficial effects

[0023] Compared with the existing methods, the directional long-hole segmented pulse fracturing method and equipment for coal rock formations in mines of the present invention have the following technical advantages: First, the coal seam permeability is increased and gas is extracted. The directional long-hole segmented pulse fracturing for permeability enhancement and gas extraction in low-permeability coal seams uses the segmented pulse fracturing method to form a uniform fracture network in the coal seam, increase the fracture area, and increase the number of fluid migration channels, thereby improving the reservoir permeability.

[0024] Second, to weaken the hard top coal, the system and method of the present invention uses directional long drilling and segmented pulse fracturing to weaken it. Specifically, a uniform crack network is formed in the coal seam through the segmented pulse fracturing method in the fully-mechanized caving working face, which fully cuts the coal body, reduces the strength of the coal body, and thus reduces the size of the top coal falling.

[0025] Third, the strength of coal and rock is weakened and the impact is reduced. The directional long drilling segmented pulse fracturing to reduce the impact of coal and rock formations is to construct a long borehole in the coal seam or rock formation to reach the high stress area, and perform segmented pulse fracturing in the high stress area to weaken the coal and rock formation, transfer the high stress, and reduce the probability of coal and rock formation impact hazards, thereby ensuring safe and efficient production in the mine.

[0026] Fourth, the present invention's directional long-bore segmented pulse fracturing technology performs pulse fracturing in segments within a long directional borehole in a coal seam. High-frequency pulse water pressure causes fatigue damage to the coal, forming multi-directional hydraulic fractures uncontrolled by ground stress, and activates the original fractures in the coal seam, forming a fracture network. This technology can effectively overcome the drawback of uneven distribution of fractures caused by overall fracturing of long boreholes, solving the problem of cracks being "dense on the outside and sparse on the inside." This technology significantly improves the fracturing effect of long boreholes. Furthermore, with the help of a directional drilling rig, the method is simple, construction is convenient, easy to operate, and safe and reliable.

[0027] Fifth, the sealing process, the sealing process of the segmented pulse fracturing technology for directional long drilling of coal rock formations in mines adopts the "double-seal medium pressure" technology. The technology relies on the directional drilling rig to connect two sealers to the drill rod of the drilling rig. After the sealer is pushed to the specified position, pulse water is injected to expand the sealer. When the pressure reaches the set pressure, the one-way valve on the sealer opens, and the one-way valve of the sealer near the bottom of the hole opens toward the hole mouth, and the one-way valve of the sealer near the hole mouth opens toward the bottom of the hole. Pulse water is injected between the two sections of the sealer for fracturing.

[0028] Sixth, the design of the segmented pulse fracturing position is affected by the thickness, undulation and directional drilling construction accuracy of the coal seam. The directional long borehole will alternate between penetrating the rock layer and the coal seam. Since there is a layer between the coal seam and the rock layer, this layer is a weak structure inside the borehole. If the sealing position is arranged in the rock layer, the cracks will mainly expand from the coal-rock layer. At the same time, in order to facilitate the backward segmented fracturing, the fracturing distance of each section needs to be set to be consistent, reducing the number of drilling withdrawal and rod delivery, and improving the fracturing efficiency. High requirements are placed on the design of the sealing position of the segmented pulse fracturing in the directional long borehole. Therefore, in order to improve the permeability of the coal seam, the sealing position should be arranged in the coal seam as much as possible, while ensuring that the fracturing distance of each section is consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 shows the directional long-hole segmented pulse fracturing pumping and monitoring system of the present invention; Figure 2 shows the directional long-hole segmented pulse fracturing string and sealing equipment of the present invention; Figure 3 shows the directional long-hole segmented pulse fracturing process for the working face level lane along the bedding layer; Figure 4 shows the directional long-hole segmented pulse fracturing process for the bottom pumping lane through the bedding layer; Figure 5 shows the directional long-hole segmented pulse fracturing process for the roof of a soft coal seam; Figure 6 shows the directional long-hole segmented pulse fracturing process for the hard roof; In the figure, 1. pulse pump, 2. pulse pump outlet valve, 3. high-pressure hose, 4. tee, 5. high-pressure hose pressure relief valve, 6. flow sensor, 7. pressure sensor, 8. flow measuring line, 9. pressure measuring line, 10. measuring and controlling instrument, 11. high-pressure sealed directional drill pipe joint, 12. drill bit, 13. first high-pressure sealed directional drill pipe, 14. hole sealer joint near the orifice end, 15. hole sealer near the orifice end, 16. adapter near the orifice end, 17. adapter near the bottom end of the hole, 18. hole sealer joint near the bottom end of the hole, 19. hole sealer near the bottom end of the hole, 20. high-pressure sealed semi-closed directional drill pipe, 21. fluid channel, 22. water outlet (one-way valve), 23. closed section, 24. fracturing interval, 25. roof, 26. coal seam, 27. floor, 28. coal seam roadway, 29. bottom extraction roadway, 30. directional long borehole, 31. fracturing network. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] As shown in Figures 1 and 2, a staged pulse fracturing device for directional long-hole drilling in a mine comprises a pulse pump 1, a pulse pump outlet valve 2, a high-pressure hose 3, a high-pressure sealed directional drill pipe joint 11, a high-pressure sealed directional drill pipe 13, a staged pulse fracturing sealing device, and a drill bit 12, connected end to end. The pulse pump outlet valve 2, a high-pressure hose pressure relief valve 5, a tee 4, a flow sensor 6, and a pressure sensor 7 are arranged in sequence on the high-pressure hose 3 along the direction of fluid flow. The flow sensor 6 is connected to a measuring and control instrument 10 via a flow measurement line 8, and the pressure sensor 7 is connected to the measuring and control instrument 10 via a pressure measurement line 9. The measuring and control instrument 10 displays and records the information in real time.

[0032] The segmented pulse fracturing sealing device includes a plurality of first high-pressure sealed directional drill pipes 13, a sealer joint 14, a near-hole end sealer 15, a near-hole end adapter 16, a plurality of second high-pressure sealed directional drill pipes, a near-hole bottom end adapter 17, a near-hole bottom end sealer joint 18, a near-hole bottom end sealer 19, and a high-pressure sealed semi-enclosed directional drill pipe 20 connected in sequence; the high-pressure sealed semi-enclosed directional drill pipe is connected between the near-hole bottom end sealer and the drill bit, with a closed section 23 at the near-hole bottom end and an open near-hole end.

[0033] A segmented pulse method for directional long drilling of coal rock formations in mines, the operating steps are as follows: S1. Design a directional long drilling trajectory for the coal rock formation according to the target coal rock formation to be transformed and the drilling construction site, and construct a directional long borehole to the target coal rock formation according to the designed trajectory by a directional drilling rig; S2. Determine the number of directional long drilling pulse hydraulic fracturing sections, segment lengths and sealing positions of each fracturing interval according to the actual construction trajectory of the directional long drilling and the actual length in the target coal rock formation; S3. Before pulse hydraulic fracturing, use a directional drilling rig to sweep the constructed directional long borehole to remove debris in the hole; S4. After the sweeping is completed, withdraw the drill rod and drill bit, connect the sealing device and the high-pressure sealing pipe string, and use the directional drilling rig to send the high-pressure sealing pipe string and the sealing device to the first fracturing position; S5. Separate the directional drilling rig from the high-pressure sealing drill rod, and connect the high-pressure sealing drill rod, high-pressure hose and pulse hydraulic fracturing pump; S6. Open the pulse pump outlet valve, close the pressure relief valve, and then open the pulse fracturing pump to perform the first stage of pulse fracturing: S7. After the first stage of fracturing is completed, turn off the pump to release the pressure, and use the directional drilling rig to retreat the high-pressure sealed drill pipe and the sealing device to the second stage designed sealing position; S71. Turn off the pulse pump and relieve the pressure on the pipeline through the high-pressure hose pressure relief valve; S72. Remove the high-pressure hose from the high-pressure sealing installation rod joint; S73. Remove the high-pressure sealed directional drill pipe joint, use the directional drilling rig to withdraw the high-pressure sealed drill pipe, and remove the multiple second high-pressure sealed directional drill pipes near the hole end so that the sealing device can be retreated to the second stage fracturing point; S8. Connect the high-pressure sealed directional drill pipe adapter between the high-pressure hose and the high-pressure sealed directional drill pipe, and turn on the pulse fracturing pump to perform the second stage of fracturing: S9. Repeat S5-S8 until the staged pulse fracturing of the entire borehole is completed; S10. Use the directional drilling rig to withdraw all high-pressure sealed drill pipes and sealing devices in the borehole; S11. Observe and evaluate the pulse hydraulic fracturing effect according to the construction purpose of the segmented pulse fracturing.

[0034] Preferably, a process for segmented pulse fracturing by directional long drilling in a working face lane along the layer, wherein the drilling construction site in step S1 is the return air lane / transport lane of the working face, the target stratum to be transformed is a coal seam, and a directional drilling rig is used to construct a segmented pulse fracturing by directional long drilling in the return air lane / transport lane of the working face toward the coal seam, thereby transforming the coal seam; Preferably, a process for segmented pulse fracturing by directional long drilling through the layer of a bottom pumping lane, wherein the drilling construction site in step S1 is the bottom pumping lane of the coal seam, the target stratum to be transformed is a coal seam, and a directional drilling rig is used to construct a segmented pulse fracturing by directional long drilling in the bottom pumping lane toward the coal seam, thereby transforming the coal seam; Preferably, a directional long drilling and segmented pulse fracturing process for the roof of a soft coal seam, the drilling construction site in step S1 is the return air lane / transport lane of the working face, and the target layer to be transformed is the soft coal seam. Due to the soft coal seam, the hole collapse is serious when drilling in the soft coal seam, the drilling effect is poor, and the cracks formed by fracturing will close quickly under the closing stress. A directional drilling rig is used to construct a through-layer directional long drill hole in the return air lane / transport lane of the working face to the coal seam roof for segmented pulse fracturing, so that the roof fracturing cracks penetrate the soft coal seam, forming a connected crack network in the roof and the soft coal seam, thereby realizing the fracturing transformation of the soft coal seam; Preferably, a directional long drilling and segmented pulse fracturing process for the roof of a soft coal seam, in order to ensure that the roof pulse fracturing cracks penetrate the soft coal seam, the vertical distance between the directional long drill hole in the roof and the coal seam should be no more than 5m, and during pulse fracturing, the fracturing time should be extended by half an hour relative to the fracturing in the soft coal seam; Preferably, a hard roof directional long drilling segmented pulse fracturing process, in step S1, the drilling construction site is the working face return air lane / transport lane, the target layer to be transformed is the roof rock layer, and a directional drilling rig is used to construct a through-layer directional long drill hole in the working face return air lane / transport lane toward the roof rock layer to perform segmented pulse fracturing to transform the roof rock layer; Preferably, the connection of the sealing device and the high-pressure sealed drill pipe in step S4 refers to connecting the drill bit, the high-pressure sealed semi-sealed directional drill pipe, the near-hole bottom end sealer, the near-hole bottom end sealer joint, the near-hole bottom end variable joint, multiple high-pressure sealed directional drill pipes, the near-hole end variable joint, the near-hole end sealer, the near-hole end sealer joint, and multiple high-pressure sealed directional drill pipes through threads and sealing, and sequentially sending them into the borehole using a directional drilling rig; Preferably, the connecting of the high-pressure sealed drill pipe, the high-pressure hose and the pulse hydraulic fracturing pump in step S5 refers to sequentially connecting the high-pressure sealed directional drill pipe at the outermost end of the orifice with the high-pressure sealed directional drill pipe joint, the high-pressure hose, the flow sensor, the fracturing sensor, the high-pressure hose pressure relief valve, the pulse pump outlet valve and the pulse pump, and the high-pressure sealed directional drill pipe joint and the high-pressure hose are connected by a U-shaped card; preferably, the flow sensor is connected to the measuring and controlling instrument through a flow measuring line, and the pressure sensor is connected to the measuring and controlling instrument through a pressure measuring line.

[0035] Preferably, the pulse hydraulic fracturing process in step S6 is to inject pulse water through a pulse pump, and the pulse water passes through a high-pressure hose, a pulse pump outlet valve, a tee, a flow sensor, a pressure sensor, a high-pressure sealed directional drill pipe joint, a plurality of first high-pressure sealed directional drill pipes, a near-hole end sealer joint, a near-hole end sealer, a near-hole end sealer joint, a plurality of second high-pressure sealed directional drill pipes, a near-hole bottom end change joint, a near-hole bottom end sealer joint, a near-hole bottom end sealer and a high-pressure sealed semi-sealed directional drill pipe. Directional drill pipe, with the injection of high-pressure water, the hole sealer near the hole end and the hole sealer near the bottom end expand, forming a closed space between the two hole sealers. When the pulse water pressure in the pipeline exceeds the pressure of the one-way valve on the change joint near the hole end and the change joint near the bottom end, the pulse water enters the closed area between the hole sealer near the hole end and the hole sealer near the bottom end. The pulse water acts on the borehole wall to form a damaged crack zone. With the continuous injection of pulse water, the damaged crack zone expands and extends to form a pulse water pressure crack network. Preferably, the purposes of the segmented pulse fracturing construction in step S11 include increasing the permeability of low-permeability coal seams, weakening the hard top coal, and reducing the impact of coal rock strength weakening; Preferably, the segmented pulse fracturing for increasing permeability of low-permeability coal seams by directional long drilling is to form a uniform fracture network in the coal seam by the segmented pulse fracturing method, increase the fracture area, increase the number of fluid migration channels, and thus improve the reservoir permeability; Preferably, the observation of the effect of the segmented pulse fracturing for increasing permeability of low-permeability coal seams by directional long drilling includes the concentration, flow rate and pure amount of borehole gas extraction after segmented pulse fracturing.

[0036] Preferably, the weakening of the hard top coal by directional long drilling segmented pulse fracturing is to form a uniform crack network in the coal seam by the segmented pulse fracturing method in the comprehensive mining working face, fully cut the coal body, reduce the strength of the coal body, and thus reduce the size of the top coal falling; Preferably, the observation of the weakening effect of the directional long drilling segmented pulse fracturing of the hard top coal includes the size of the top coal falling after the segmented pulse fracturing; Preferably, the shock reduction of the coal rock formation by directional long drilling segmented pulse fracturing is to construct a long borehole in the coal seam or rock formation to reach a high stress area, perform segmented pulse fracturing in the high stress area, weaken the coal rock formation, transfer the high stress, and reduce the probability of coal rock formation impact hazard, thereby ensuring safe and efficient production of the mine; Preferably, the observation of the shock reduction effect of the directional long drilling segmented pulse fracturing of the coal rock formation includes the coal rock formation impact energy events and energy amplitude after the segmented pulse fracturing.

[0037] Example 1: Gas extraction by directional long drilling and segmented pulse fracturing in the horizontal lane of low permeability coal seam working face: A certain mine is a high-gas mine. The absolute gas emission volume of the mine is 16.62m 3 / min, the relative gas outflow rate is 6.86m 3 The coal seam has a dip angle of 1 to 3 degrees and is nearly horizontal. The coal seam thickness ranges from 3.52 to 5.86 meters, with an average thickness of 4.62 meters.

[0038] As shown in FIG3 , a method for pulse fracturing of a directional long drilling hole in a low permeability coal seam working face in a horizontal lane is provided. The operation steps are as follows: (1) Designing a directional long drilling trajectory for the coal seam, using a directional drilling rig to construct a directional long drilling hole 30 in the coal seam 26 in the return air lane / transport lane 28 of the working face. The drilling depth should be greater than 50 m to avoid the fracturing crack network 31 from penetrating the lane; (2) According to the actual construction trajectory of the directional long drilling hole 30 and the actual length in the target coal seam, determine the number of pulse hydraulic fracturing sections, the length of the sections, and the sealing position of each fracturing interval of the directional long drilling hole; (3) Before pulse hydraulic fracturing, use a directional drilling rig to clean the constructed directional long drilling hole 30 to remove debris in the hole; (4) After the hole sweeping is completed, the drill pipe and the drill bit 12 are withdrawn, and the drill bit 12, the high-pressure sealed semi-enclosed directional drill pipe 20, the hole sealer 19 at the bottom of the hole, the hole sealer joint 18 at the bottom of the hole, the near-bottom-end adapter 17, multiple high-pressure sealed directional drill pipes 13, the hole mouth adapter 16, the hole sealer 15 at the bottom of the hole, the hole sealer joint 14 at the bottom of the hole, multiple high-pressure sealed directional drill pipes 13, and the high-pressure sealed directional drill pipe joint 11 are sequentially connected and sealed through threads, and then sent into the first fracturing position in the borehole in sequence using a directional drilling rig; (5) ① Separate the directional drilling rig from the high-pressure sealed drill pipe, and connect the high-pressure sealed directional drill pipe at the outermost end of the hole to the high-pressure sealed directional drill pipe joint 11, high-pressure hose 3, flow sensor 6, fracturing sensor 7, high-pressure hose pressure relief valve 5, tee 4, pulse pump outlet valve 2, and pulse pump 1 in turn. The high-pressure sealed directional drill pipe joint 11 is connected to the high-pressure hose 3 through a U-shaped card; ② Connect the flow sensor 6 to the measuring and control instrument 10 through the flow measuring line 8, and connect the pressure sensor 7 to the measuring and control instrument 10 through the pressure measuring line 9.

[0039] (6) ①Open the pulse pump outlet valve 2, close the pressure relief valve 5, and perform the first pulse fracturing: ②Inject pulse water through the pulse pump 1, and the pulse water passes through the high-pressure hose 3, the pulse pump outlet valve 2, the tee 4, the flow sensor 6, the pressure sensor 7, the high-pressure sealed directional drill pipe joint 11, the high-pressure sealed directional drill pipe 13, the near-hole end sealer joint 14, the near-hole end sealer 15, the near-hole end sealer joint 16, multiple high-pressure sealed directional drill pipes 13, the near-hole bottom end adapter 17, the near-hole bottom end sealer joint 18, the near-hole bottom end sealer 19 and the high-pressure sealed semi-closed directional drill pipe In the fluid channel 21 of 20, as high-pressure water is injected, the sealer 15 near the orifice end and the sealer 19 near the bottom of the hole expand, forming a closed fracturing interval 24 between the two sealers. When the pulse water pressure in the pipeline exceeds the one-way valve pressure on the adapter 16 near the orifice end and the adapter 17 near the bottom of the hole, the pulse water enters the closed fracturing interval 24 between the sealer 15 near the orifice end and the sealer 19 near the bottom of the hole through the sealer outlet 22. The pulse water acts on the borehole wall to form a damaged crack zone. As the pulse water is continuously injected, the damaged crack zone expands and extends to form a pulse water pressure crack network.

[0040] (7) After the first stage of fracturing is completed, turn off the pump to release the pressure, and use the directional drilling rig to move the high-pressure sealing drill pipe and the sealing device back to the second stage of the designed sealing position; ① Turn off the pulse pump 1, and use the high-pressure hose pressure relief valve 5 to relieve the pressure on the pipeline. When the pressure is small or no high-pressure water is sprayed, continue to relieve the pressure for 3 to 5 minutes to ensure that the pressure in the pipeline is completely relieved; ② Remove the high-pressure hose 3 from the high-pressure sealing installation rod joint 11; ③ Remove the high-pressure sealing directional drill pipe joint 11, use the directional drilling rig to withdraw the high-pressure sealing drill pipe, and remove the high-pressure sealing directional drill pipe 13 near the hole end so that the sealing device can be retreated to the second stage of fracturing; (8) Connect the high-pressure sealing directional drill pipe adapter 11 between the high-pressure hose 3 and the high-pressure sealing directional drill pipe 13, and turn on the pulse fracturing pump 1 to perform the second stage of fracturing: (9) Repeat S5-S8 until the segmented pulse fracturing of the entire borehole is completed; (10) Use the directional drilling rig to withdraw all high-pressure sealing drill pipes and sealing devices in the borehole; (11) Gas extraction. Remove the segmented pulse fracturing system and drill bit 21 from the borehole, connect the extraction pipeline, and extract gas from the coal seam in the area; (12) Move the directional long-hole segmented pulse fracturing system to the next borehole and repeat steps 1 to 10 to achieve permeability enhancement and extraction in the working face or designated area; (13) During the gas extraction process, monitor the gas concentration, flow rate, and pure quantity of the extraction borehole to observe and evaluate the effect of the pulse hydraulic fracturing.

[0041] Example 2: Directional long drilling and segmented pulse fracturing to enhance permeability and eliminate outbursts in a low-permeability coal seam. A coal mine is an outburst mine. A certain working face is the first mining face on the east wing of the second mining area. The working face is generally a monocline structure with no fault exposed on the surface. The mined coal seam is the 9# coal seam with a burial depth of 100 to 300m, a coal seam dip of 4° to 7°, a thickness of 2.00 to 4.47m, and an average of 3.18m. The coal seam gas pressure is 0.07 to 0.91MPa, and the gas content is 9.20 to 14.41m 3 / t. The initial velocity of coal gas emission is 18-29 mmHg, the coal strength coefficient f is 1.00-1.70, and the coal damage type is Class II. The coal seam permeability coefficient is 0.140-0.636m 2 / (MPa 2 ·d).

[0042] As shown in FIG4 , a method for enhancing permeability and eliminating bursts by directional long drilling and segmented pulse fracturing in the bottom extraction lane of a low permeability coal seam is provided. The operation steps are as follows: (1) Designing a directional long drilling trajectory for the coal seam, using a directional drilling rig to construct a directional long borehole 30 from the bottom extraction lane 29 toward the coal seam 26. The drilling depth should be greater than 50 m to avoid the fracturing crack network 31 from penetrating the lane; (2) According to the actual construction trajectory of the directional long borehole 30 and the actual length in the target coal seam, determine the number of directional long borehole pulse hydraulic fracturing sections, the segment length, and the sealing position of each fracturing interval; (3) Before pulse hydraulic fracturing, use a directional drilling rig to clean the constructed directional long borehole 30 to remove debris in the hole; (4) After the hole sweeping is completed, the drill pipe and the drill bit 12 are withdrawn, and the drill bit 12, the high-pressure sealed semi-enclosed directional drill pipe 20, the hole sealer 19 at the bottom of the hole, the hole sealer joint 18 at the bottom of the hole, the near-bottom-end adapter 17, multiple high-pressure sealed directional drill pipes 13, the hole mouth adapter 16, the hole sealer 15 at the bottom of the hole, the hole sealer joint 14 at the bottom of the hole, multiple high-pressure sealed directional drill pipes 13, and the high-pressure sealed directional drill pipe joint 11 are sequentially connected and sealed through threads, and then sent into the first fracturing position in the borehole in sequence using a directional drilling rig; (5) ① Separate the directional drilling rig from the high-pressure sealed drill pipe, and connect the high-pressure sealed directional drill pipe at the outermost end of the hole to the high-pressure sealed directional drill pipe joint 11, high-pressure hose 3, flow sensor 6, fracturing sensor 7, high-pressure hose pressure relief valve 5, tee 4, pulse pump outlet valve 2, and pulse pump 1 in turn. The high-pressure sealed directional drill pipe joint 11 is connected to the high-pressure hose 3 through a U-shaped card; ② Connect the flow sensor 6 to the measuring and control instrument 10 through the flow measuring line 8, and connect the pressure sensor 7 to the measuring and control instrument 10 through the pressure measuring line 9.

[0043] (6) ①Open the pulse pump outlet valve 2, close the pressure relief valve 5, and perform the first pulse fracturing: ②Inject pulse water through the pulse pump 1, and the pulse water passes through the high-pressure hose 3, the pulse pump outlet valve 2, the tee 4, the flow sensor 6, the pressure sensor 7, the high-pressure sealed directional drill pipe joint 11, the high-pressure sealed directional drill pipe 13, the near-hole end sealer joint 14, the near-hole end sealer 15, the near-hole end sealer joint 16, multiple high-pressure sealed directional drill pipes 13, the near-hole bottom end adapter 17, the near-hole bottom end sealer joint 18, the near-hole bottom end sealer 19 and the high-pressure sealed semi-closed directional drill pipe In the fluid channel 21 of 20, as high-pressure water is injected, the sealer 15 near the orifice end and the sealer 19 near the bottom of the hole expand, forming a closed fracturing interval 24 between the two sealers. When the pulse water pressure in the pipeline exceeds the one-way valve pressure on the adapter 16 near the orifice end and the adapter 17 near the bottom of the hole, the pulse water enters the closed fracturing interval 24 between the sealer 15 near the orifice end and the sealer 19 near the bottom of the hole through the sealer outlet 22. The pulse water acts on the borehole wall to form a damaged crack zone. As the pulse water is continuously injected, the damaged crack zone expands and extends to form a pulse water pressure crack network.

[0044] (7) After the first stage of fracturing is completed, turn off the pump to release the pressure, and use the directional drilling rig to move the high-pressure sealing drill pipe and the sealing device back to the second stage of the designed sealing position; ① Turn off the pulse pump 1, and use the high-pressure hose pressure relief valve 5 to relieve the pressure on the pipeline. When the pressure is small or no high-pressure water is sprayed, continue to relieve the pressure for 3 to 5 minutes to ensure that the pressure in the pipeline is completely relieved; ② Remove the high-pressure hose 3 from the high-pressure sealing installation rod joint 11; ③ Remove the high-pressure sealing directional drill pipe joint 11, use the directional drilling rig to withdraw the high-pressure sealing drill pipe, and remove the high-pressure sealing directional drill pipe 13 near the hole end so that the sealing device can be retreated to the second stage of fracturing; (8) Connect the high-pressure sealing directional drill pipe adapter 11 between the high-pressure hose 3 and the high-pressure sealing directional drill pipe 13, and turn on the pulse fracturing pump 1 to perform the second stage of fracturing: (9) Repeat S5-S8 until the segmented pulse fracturing of the entire borehole is completed; (10) Use the directional drilling rig to withdraw all high-pressure sealing drill pipes and sealing devices in the borehole; (11) Gas extraction. Remove the segmented pulse fracturing system and drill bit 21 from the borehole, connect the extraction pipeline, and extract gas from the coal seam in the area; (12) Move the directional long-hole segmented pulse fracturing system to the next borehole and repeat steps 1 to 10 to achieve permeability enhancement, extraction, and gas burst elimination in the working face or designated area; (13) During the gas extraction process, monitor the gas concentration, flow rate, and pure quantity of the extraction borehole to observe and evaluate the effect of the pulse hydraulic fracturing.

[0045] Example 3: Directional Long Drilling and Segmented Pulse Fracturing for Roof Enhancement and Bulge Reduction in Soft Coal Seams. A coal mine is a bulge mine. The designed strike length of a fully mechanized caving working face averages 1850 meters, with a dip length of 200 meters. The coal seams are relatively stable, with dip angles of 0-12° (average 6°) and thicknesses of 4-20 meters (average 13.4 meters). Comprehensive analysis of nearby drill hole data reveals 1-4 interbedded gangue layers, primarily mudstone, with a thickness of 0.2-0.3 meters. The coal seams are relatively soft, with a coal strength coefficient f ranging from 1.20 to 1.60, and the roof of the coal seams is composed of fine sandstone.

[0046] As shown in FIG5 , a method for enhancing permeability and eliminating bursts by segmented pulse fracturing with directional long drilling in the roof of a soft coal seam is described. The specific operation steps are as follows: (1) Designing a directional long drilling trajectory for the coal rock layer, using a directional drilling rig to construct a through-layer directional long drill hole 30 in the return air lane / transport lane 28 of the working face toward the coal seam roof 25. The drilling depth should be greater than 50 m to avoid the fracturing crack network 31 from penetrating the lane; to ensure that the fracturing crack network 31 can penetrate the coal seam, the vertical distance between the directional long drill hole in the roof 25 and the coal seam 26 should be no greater than 5 m.

[0047] (2) According to the actual construction trajectory of the directional long borehole 30 and the actual length in the target coal and rock formation, the number of pulse hydraulic fracturing sections, the length of each section and the sealing position of each fracturing interval of the directional long borehole are determined; (3) Before pulse hydraulic fracturing, the constructed directional long borehole 30 is cleaned by a directional drilling rig to remove debris in the hole; (4) After the cleaning is completed, the drill pipe and the drill bit 12 are withdrawn, and the drill bit 12, the high-pressure sealed semi-closed directional drill pipe 20, the near-hole bottom sealer 19, the near-hole bottom sealer joint 18, the near-hole bottom adapter 17, multiple high-pressure sealed directional drill pipes 13, the near-hole end adapter 16, the near-hole end sealer 15, the near-hole end sealer joint 14, multiple high-pressure sealed directional drill pipes 13, and the high-pressure sealed directional drill pipe joint 11 are sequentially connected and sealed through threads, and then sent into the first fracturing position in the borehole by the directional drilling rig in sequence; (5) ① Separate the directional drilling rig from the high-pressure sealed drill pipe, and connect the high-pressure sealed directional drill pipe at the outermost end of the hole to the high-pressure sealed directional drill pipe joint 11, high-pressure hose 3, flow sensor 6, fracturing sensor 7, high-pressure hose pressure relief valve 5, tee 4, pulse pump outlet valve 2, and pulse pump 1 in turn. The high-pressure sealed directional drill pipe joint 11 is connected to the high-pressure hose 3 through a U-shaped card; ② Connect the flow sensor 6 to the measuring and control instrument 10 through the flow measuring line 8, and connect the pressure sensor 7 to the measuring and control instrument 10 through the pressure measuring line 9.

[0048] (6) ①Open the pulse pump outlet valve 2, close the pressure relief valve 5, and perform the first pulse fracturing: ②Inject pulse water through the pulse pump 1, and the pulse water passes through the high-pressure hose 3, the pulse pump outlet valve 2, the tee 4, the flow sensor 6, the pressure sensor 7, the high-pressure sealed directional drill pipe joint 11, the high-pressure sealed directional drill pipe 13, the near-hole end sealer joint 14, the near-hole end sealer 15, the near-hole end sealer joint 16, multiple high-pressure sealed directional drill pipes 13, the near-hole bottom end change joint 17, the near-hole bottom end sealer joint 18, the near-hole bottom end sealer 19 and the fluid channel 21 of the high-pressure sealed semi-closed directional drill pipe 20. With the injection of high-pressure water, the near-hole end sealer 15 and the near-hole bottom end sealer 19 expands, forming a closed fracturing interval 24 between the two sealers. When the pulse water pressure in the pipeline exceeds the one-way valve pressure on the near-hole end adapter 16 and the near-hole bottom end adapter 17, the pulse water enters the closed fracturing interval 24 between the near-hole end sealer 15 and the near-hole bottom end sealer 19 through the sealer outlet 22. The pulse water acts on the borehole wall to form a damaged crack zone. With the continuous injection of pulse water, the damaged crack zone expands and extends to form a pulse water pressure crack network. In order to make the roof pulse fracturing crack penetrate the coal seam and form a connected crack network in the roof and coal seam, thereby realizing the fracturing transformation of the coal seam, during pulse fracturing, the fracturing time should be extended by about half an hour relative to the coal seam fracturing. (7) After the first stage of fracturing is completed, turn off the pump to release the pressure, and use the directional drilling rig to move the high-pressure sealing drill pipe and the sealing device back to the second stage of the designed sealing position; ① Turn off the pulse pump 1, and use the high-pressure hose pressure relief valve 5 to relieve the pressure on the pipeline. When the pressure is small or no high-pressure water is sprayed, continue to relieve the pressure for 3 to 5 minutes to ensure that the pressure in the pipeline is completely relieved; ② Remove the high-pressure hose 3 from the high-pressure sealing installation rod joint 11; ③ Remove the high-pressure sealing directional drill pipe joint 11, use the directional drilling rig to withdraw the high-pressure sealing drill pipe, and remove the high-pressure sealing directional drill pipe 13 near the hole end so that the sealing device can be retreated to the second stage of fracturing; (8) Connect the high-pressure sealing directional drill pipe adapter 11 between the high-pressure hose 3 and the high-pressure sealing directional drill pipe 13, and turn on the pulse fracturing pump 1 to perform the second stage of fracturing: (9) Repeat S5-S8 until the segmented pulse fracturing of the entire borehole is completed; (10) Use the directional drilling rig to withdraw all high-pressure sealing drill pipes and sealing devices in the borehole; (11) Gas extraction. Remove the segmented pulse fracturing system and drill bit 21 from the borehole, connect the extraction pipeline, and extract gas from the coal seam in the area; (12) Move the directional long-hole segmented pulse fracturing system to the next borehole and repeat steps 1 to 10 to achieve permeability enhancement, extraction, and gas burst elimination in the working face or designated area; (13) During the gas extraction process, monitor the gas concentration, flow rate, and pure quantity of the extraction borehole to observe and evaluate the effect of the pulse hydraulic fracturing.

[0049] Example 4: Segmented pulse fracturing to reduce rock bursts in a hard roof using directional long-hole drilling. A coal mine is a rock burst mine. Data from the 170-hole drill hole in the middle of a working face show that there is a 30.87-m-thick medium-grained sandstone 9.24 m above the working face, and another 13.38-m-thick fine-grained sandstone layer 87.71 m from the coal seam. This results in frequent microseismic high-energy events during mining operations at the working face.

[0050] A method for reducing shock by segmented pulse fracturing of a hard roof using directional long drilling (Figure 6) is described. The specific steps are as follows: (1) Designing a directional long drilling trajectory for a coal seam, using a directional drilling rig to construct a directional long borehole 31 in a coal seam tunnel 28 at the working face toward the hard roof 25 above the coal seam. The drilling depth should be greater than 50 m to prevent the fracturing crack network 31 from penetrating the tunnel; (2) Determining the number of pulse hydraulic fracturing segments, segment lengths, and sealing positions of each fracturing interval for the directional long drilling based on the actual construction trajectory of the directional long drilling hole 30 and its actual length in the target coal seam; (3) Before pulse hydraulic fracturing, using a directional drilling rig to sweep the constructed directional long drilling hole 30 to remove debris in the hole; (4) After the hole sweeping is completed, the drill pipe and the drill bit 12 are withdrawn, and the drill bit 12, the high-pressure sealed semi-enclosed directional drill pipe 20, the hole sealer 19 at the bottom of the hole, the hole sealer joint 18 at the bottom of the hole, the near-bottom-end adapter 17, multiple high-pressure sealed directional drill pipes 13, the hole mouth adapter 16, the hole sealer 15 at the bottom of the hole, the hole sealer joint 14 at the bottom of the hole, multiple high-pressure sealed directional drill pipes 13, and the high-pressure sealed directional drill pipe joint 11 are sequentially connected and sealed through threads, and then sent into the first fracturing position in the borehole in sequence using a directional drilling rig; (5) ① Separate the directional drilling rig from the high-pressure sealed drill pipe, and connect the high-pressure sealed directional drill pipe at the outermost end of the hole to the high-pressure sealed directional drill pipe joint 11, high-pressure hose 3, flow sensor 6, fracturing sensor 7, high-pressure hose pressure relief valve 5, tee 4, pulse pump outlet valve 2, and pulse pump 1 in turn. The high-pressure sealed directional drill pipe joint 11 is connected to the high-pressure hose 3 through a U-shaped card; ② Connect the flow sensor 6 to the measuring and control instrument 10 through the flow measuring line 8, and connect the pressure sensor 7 to the measuring and control instrument 10 through the pressure measuring line 9.

[0051] (6) ①Open the pulse pump outlet valve 2, close the pressure relief valve 5, and perform the first pulse fracturing: ②Inject pulse water through the pulse pump 1, and the pulse water passes through the high-pressure hose 3, the pulse pump outlet valve 2, the tee 4, the flow sensor 6, the pressure sensor 7, the high-pressure sealed directional drill pipe joint 11, the high-pressure sealed directional drill pipe 13, the near-hole end sealer joint 14, the near-hole end sealer 15, the near-hole end sealer joint 16, multiple high-pressure sealed directional drill pipes 13, the near-hole bottom end adapter 17, the near-hole bottom end sealer joint 18, the near-hole bottom end sealer 19 and the high-pressure sealed semi-closed directional drill pipe In the fluid channel 21 of 20, as high-pressure water is injected, the sealer 15 near the orifice end and the sealer 19 near the bottom end of the hole expand, forming a closed fracturing zone 24 between the two sealers. When the pulse water pressure in the pipeline exceeds the pressure of the one-way valves on the adapter 16 near the orifice end and the adapter 17 near the bottom end of the hole, the pulse water enters the closed fracturing zone 24 between the sealer 15 near the orifice end and the sealer 19 near the bottom end of the hole through the sealer outlet 22. The pulse water acts on the borehole wall to form a damaged crack zone. As the pulse water is continuously injected, the damaged crack zone expands and extends to form a pulse water pressure crack network. (7) After the first stage of fracturing is completed, turn off the pump to release the pressure, and use the directional drilling rig to move the high-pressure sealing drill pipe and the sealing device back to the second stage of the designed sealing position; ① Turn off the pulse pump 1, and use the high-pressure hose pressure relief valve 5 to relieve the pressure on the pipeline. When the pressure is small or no high-pressure water is sprayed, continue to relieve the pressure for 3 to 5 minutes to ensure that the pressure in the pipeline is completely relieved; ② Remove the high-pressure hose 3 from the high-pressure sealing installation rod joint 11; ③ Remove the high-pressure sealing directional drill pipe joint 11, use the directional drilling rig to withdraw the high-pressure sealing drill pipe, and remove the high-pressure sealing directional drill pipe 13 near the hole end so that the sealing device can be retreated to the second stage of fracturing; (8) Connect the high-pressure sealing directional drill pipe adapter 11 between the high-pressure hose 3 and the high-pressure sealing directional drill pipe 13, and turn on the pulse fracturing pump 1 to perform the second stage of fracturing: (9) Repeat S5-S8 until the segmented pulse fracturing of the entire borehole is completed; (10) Use the directional drilling rig to withdraw all high-pressure sealing drill pipes and sealing devices in the borehole; (11) Move the directional long-hole segmented pulse fracturing system to the next borehole and repeat steps 1 to 10 to achieve pulse fracturing pressure relief for the working face or designated area; (12) Evaluate the impact reduction effect. During the mining process of the working face, monitor the large-energy microseismic events of the roof rock fracture, compare and analyze the frequency and intensity of large-energy microseismic events before and after fracturing, and then evaluate the impact reduction effect of the directional long-hole segmented pulse fracturing on the hard roof.

[0052] The advantages of the present invention are as follows: This system combines the advantages of staged fracturing and pulse fracturing to realize a method and equipment for staged pulse fracturing in directional long boreholes in mines.

[0053] 2. This system adopts the "double-seal medium-pressure" technology through the segmented pulse fracturing technology of directional long drilling in coal and rock formations in mines. The technology relies on the directional drilling rig to connect two sealers to the drill rod of the drilling rig. After the sealer is pushed to the specified position, pulse water is injected to expand the sealer. When the pressure reaches the set pressure, the one-way valve on the sealer opens. The one-way valve of the sealer near the bottom of the hole opens toward the hole mouth, and the one-way valve of the sealer near the hole mouth opens toward the bottom of the hole. Pulse water is injected between the two sealers for fracturing.

[0054] 3. This system provides the design principles for the sealing position of the sealer. It is recommended that the sealing position be arranged in the coal seam as much as possible, while ensuring that the fracturing distance of each section is consistent.

[0055] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modifications and equivalent changes made to the above embodiment based on the technical essence of the present invention fall within the scope of protection of the present invention.

Claims

1. A directional long-hole segmented pulse fracturing method for coal and rock formations in a mine, characterized in that: The following steps are involved: S1. According to the target coal and rock layer to be transformed and the drilling construction site, a directional long drilling trajectory of the coal and rock layer is designed, and a directional long drilling is constructed in the target coal and rock layer according to the designed trajectory by a directional drilling rig; S2. Determine the number of pulse hydraulic fracturing sections, the length of each section, and the sealing position of each fracturing interval of the directional long drilling according to the actual construction trajectory of the directional long drilling and the actual length in the target coal and rock layer; S3. Before pulse hydraulic fracturing, use a directional drill to clean the constructed directional long borehole to remove debris in the hole; S4, after the hole sweeping is completed, the drill pipe and the drill bit are withdrawn, the hole sealing device and the high-pressure sealing pipe string are connected, and the high-pressure sealing pipe string and the hole sealing device are sent to the first stage fracturing position by using a directional drilling rig; S5. Separate the directional drilling rig from the high-pressure sealed drill pipe, and connect the high-pressure sealed drill pipe, high-pressure hose and pulse hydraulic fracturing pump; S6. Open the pulse pump outlet valve, close the pressure relief valve, and then turn on the pulse fracturing pump to perform the first pulse fracturing: S7. After the first stage of fracturing is completed, the pump is turned off to release the pressure, and the high-pressure sealing drill pipe and the sealing device are moved back to the second stage of the sealing position using a directional drilling rig; S8. Connect the high-pressure sealed directional drill pipe adapter between the high-pressure hose and the high-pressure sealed directional drill pipe, and turn on the pulse fracturing pump to perform the second stage of fracturing: S9, repeating steps S5-S8 until the segmented pulse fracturing of the entire borehole is completed; S10. Use a directional drill to remove all high-pressure sealed drill rods and sealing devices in the borehole; S11. Observe and evaluate the effect of pulse hydraulic fracturing according to the construction purpose of segmented pulse fracturing.

2. The method for directional long-hole segmented pulse fracturing of coal and rock strata in mines according to claim 1, characterized in that: In step S1, the drilling construction site is the return air lane / transport lane of the working face, and the target layer to be transformed is the coal seam. A directional drilling rig is used to construct long directional holes along the coal seam in the return air lane / transport lane of the working face to perform segmented pulse fracturing to transform the coal seam.

3. The method for directional long-hole segmented pulse fracturing of coal and rock strata in mines according to claim 1 is characterized in that: In step S1, the drilling construction site is the coal seam bottom extraction lane, and the target layer to be transformed is the coal seam. A directional drill is used to construct a long directional drill hole through the coal seam in the bottom extraction lane to perform segmented pulse fracturing to transform the coal seam.

4. The method for directional long-hole segmented pulse fracturing of coal and rock strata in mines according to claim 1, characterized in that: In step S1, the drilling construction site is the return air lane / transport lane of the working face, and the target stratum to be transformed is the soft coal seam. Since the coal seam is soft, the hole collapse is serious when drilling in the soft coal seam, the drilling effect is poor, and the cracks formed by fracturing will close quickly under the closing stress. A directional drilling rig is used to construct a through-layer directional long drill hole in the return air lane / transport lane of the working face toward the coal seam roof for segmented pulse fracturing, so that the roof fracturing cracks penetrate the soft coal seam, and a connected crack network is formed in the roof and the soft coal seam, thereby realizing the fracturing transformation of the soft coal seam.

5. The method for directional long-hole segmented pulse fracturing of coal and rock strata in mines according to claim 4, characterized in that: To ensure that the roof pulse fracturing cracks penetrate into the soft coal seam, the vertical distance between the directional long drill hole in the roof and the soft coal seam should not exceed 5m, and during pulse fracturing, the fracturing time should be extended by 20 to 40 minutes compared with fracturing in the soft coal seam.

6. The method for directional long-hole segmented pulse fracturing of coal and rock strata in mines according to claim 1, characterized in that: In step S1, the drilling construction site is the return air lane / transport lane of the working face, and the target layer to be transformed is the roof rock layer. A directional drilling rig is used to construct a long directional drill hole through the return air lane / transport lane of the working face toward the roof rock layer to perform segmented pulse fracturing to transform the roof rock layer.

7. The method for directional long-hole segmented pulse fracturing of coal and rock strata in a mine according to claim 1, characterized in that: In step S11, according to the purpose of the segmented pulse fracturing construction, the pulse hydraulic fracturing effect is observed and evaluated specifically: The purposes of the staged pulse fracturing construction in step S11 include increasing the permeability of low-permeability coal seams, weakening hard top coal, and weakening the strength of coal and rock to reduce shock; The low permeability coal seam directional long-hole segmented pulse fracturing permeability enhancement method is to form a uniform fracture network in the coal seam through the segmented pulse fracturing method, increase the fracture area, and increase the number of fluid migration channels, thereby improving the reservoir permeability; The hard top coal directional long drilling segmented pulse fracturing weakening method is to form a uniform fracture network in the coal seam by segmented pulse fracturing in the fully mechanized caving working face, fully cut the coal body, reduce the strength of the coal body, and thus reduce the size of the top coal falling; The coal-rock stratum directional long-hole segmented pulse fracturing shock reduction is to construct a long hole in the coal seam or rock stratum to reach the high stress area, perform segmented pulse fracturing in the high stress area, weaken the coal-rock stratum, transfer the high stress, and reduce the probability of coal-rock stratum shock hazards, thereby ensuring safe and efficient production of the mine; The observation of the permeability enhancement effect of the directional long-hole segmented pulse fracturing in the low-permeability coal seam includes: the concentration, flow rate and pure amount of gas extraction in the borehole after the segmented pulse fracturing; if the concentration, flow rate and pure amount parameters of gas extraction in the borehole after the segmented pulse fracturing increase by more than 50% compared with those before the construction, it is judged that the effect is good, and if the increase is less than 20%, it is judged that the effect is not good; The observation of weakening effect of directional long-hole segmented pulse fracturing of hard top coal includes: the size of top coal after segmented pulse fracturing; if the size of top coal after segmented pulse fracturing increases by more than 50% compared with that before construction, it is judged that the effect is good, and if the size increases by less than 20%, it is judged that the effect is not good; The observation of the impact reduction effect of the directional long-hole segmented pulse fracturing of the coal rock formation includes: the impact energy events and energy amplitudes of the coal rock formation after the segmented pulse fracturing. The impact energy events and energy amplitudes of the coal rock formation after the segmented pulse fracturing are reduced by more than 40% compared with those before the construction, which indicates a good effect; and they are reduced by less than 20%, which indicates a poor effect.

8. The segmented pulse fracturing equipment used in the segmented pulse fracturing method for directional long-hole drilling in coal and rock formations in mines as claimed in any one of claims 1 to 7, characterized in that: include: A pulse pump, a pulse pump outlet valve, a high-pressure hose, a high-pressure sealed directional drill pipe joint, a high-pressure sealed directional drill pipe, a segmented pulse fracturing sealing device and a drill bit are sequentially connected end to end, wherein the pulse pump outlet valve, the high-pressure hose pressure relief valve, a tee, a flow sensor and a pressure sensor are sequentially arranged on the high-pressure hose along the fluid flow direction; The flow sensor is connected to the measuring and controlling instrument through a flow measuring line to monitor the fluid flow in real time, which is displayed and recorded in real time by the measuring and controlling instrument; The pressure sensor is connected to the measuring and controlling instrument through a pressure measuring line to monitor the fluid pressure in real time, and the measuring and controlling instrument displays and records the pressure in real time; The segmented pulse fracturing sealing device comprises a kilometer-long directional drilling rig, a plurality of first high-pressure sealed directional drilling rods, a sealing joint, a sealing device near the hole mouth, a change joint near the hole mouth, a plurality of second high-pressure sealed directional drilling rods, a change joint near the bottom end of the hole, a sealing joint near the bottom end of the hole, a sealing device near the bottom end of the hole, and a high-pressure sealed semi-closed directional drilling rod connected in sequence; The high-pressure sealed semi-enclosed directional drill rod is connected between the hole sealer at the bottom end near the hole and the drill bit, is blocked at the bottom end near the hole, and is open at the end near the hole opening.

9. The staged pulse fracturing equipment according to claim 8, characterized in that: The high-pressure hose pressure relief valve is a high-pressure wear-resistant ball valve; The high-pressure sealed directional drill pipe joint, high-pressure sealed directional drill pipe, hole sealer joint near the hole mouth, hole sealer near the hole mouth, adapter near the hole mouth, adapter near the bottom of the hole, hole sealer joint near the bottom of the hole and hole sealer near the bottom of the hole are hollow high-pressure resistant rods; The high-pressure rubber hose and the high-pressure sealed directional drill pipe joint are connected by a U-shaped clamp; Threaded connections are adopted between the high-pressure sealed directional drill rod joint and the high-pressure sealed directional drill rod, between the high-pressure sealed directional drill rod and the hole sealer joint, between the variable joint and the hole sealer, and between the high-pressure sealed directional drill rod and the high-pressure sealed directional drill rod.

10. The staged pulse fracturing equipment according to claim 8, characterized in that: The connection of the sealing device and the high-pressure sealed drill pipe described in step S4 refers to connecting and sealing the drill bit, the high-pressure sealed semi-closed directional drill pipe, the bottom end sealer near the hole, the bottom end sealer joint near the hole, the bottom end adapter near the hole, multiple high-pressure sealed directional drill pipes, the near-hole end adapter, the near-hole end sealer, the near-hole end sealer joint and multiple high-pressure sealed directional drill pipes through threads, and then sending them into the borehole in sequence using a directional drilling rig.

11. The staged pulse fracturing equipment according to claim 8, characterized in that: The step S5 of connecting the high-pressure sealed drill pipe, the high-pressure hose and the pulse hydraulic fracturing pump means sequentially connecting the high-pressure sealed directional drill pipe at the outermost end of the orifice with the high-pressure sealed directional drill pipe joint, the high-pressure hose, the flow sensor, the fracturing sensor, the high-pressure hose pressure relief valve, the pulse pump outlet valve and the pulse pump, and the high-pressure sealed directional drill pipe joint and the high-pressure hose are connected by a U-shaped card; The flow sensor is connected to the measuring and controlling instrument via a flow measuring line, and the pressure sensor is connected to the measuring and controlling instrument via a pressure measuring line.

12. The staged pulse fracturing equipment according to claim 8, characterized in that: The pulse hydraulic fracturing process described in step S6 is to inject pulse water through a pulse pump, and the pulse water passes through a high-pressure hose, a pulse pump outlet valve, a tee, a flow sensor, a pressure sensor, a high-pressure sealed directional drill pipe joint, a plurality of first high-pressure sealed directional drill pipes, a near-hole end sealer joint, a near-hole end sealer, a near-hole end sealer joint, a plurality of second high-pressure sealed directional drill pipes, a near-hole bottom end adapter, a near-hole bottom end sealer joint, a near-hole bottom end sealer and a high-pressure sealed semi-closed directional drill pipe. With the injection of high-pressure water, the near-hole end sealer and the near-hole bottom end sealer expand to form a closed space between the two sealers. When the pulse water pressure in the pipeline exceeds the one-way valve pressure on the near-hole end adapter and the near-hole bottom end adapter, the pulse water enters the closed area between the near-hole end sealer and the near-hole bottom end sealer. The pulse water acts on the borehole wall to form a damaged crack zone. With the continuous injection of pulse water, the damaged crack zone expands and extends to form a pulse water pressure crack network.

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