Method for constructing artificial water guide channel through drainage borehole in roof aquifer by means of pulse fracturing

Abstract

The present invention relates to the technical field of coal mining, in particular to a method for constructing an artificial water guide channel through drainage boreholes in a roof aquifer by means of pulse fracturing. The method involves arranging drainage boreholes and using pulse fracturing to pre-form an artificial water guide channel in a sandstone fracture aquifer through the arranged drainage boreholes, thereby improving the permeability of dense and intact sandstone rock masses; the artificial water guide channel formed by the drainage boreholes in the sandstone fracture aquifer connects discontinuous water-bearing areas and water-rich areas, such that roof sandstone fracture water‌ is guided to the drainage boreholes through the artificial water guide channel, thereby achieving effective drainage of the boreholes and expanding the drainage radiation range of a single borehole. The present invention not only avoids arranging excessive drainage boreholes and remarkably improves the drainage efficiency of exploratory drainage holes, but also achieves an advanced drainage function in a stoping process. By means of the method, mine water disasters can be effectively controlled even under unfordable geological conditions, thereby guaranteeing safe production at mines.

Description

Method for constructing artificial water-conducting channels by drilling and pulse fracturing in the top aquifer Technical Field

[0001] This invention relates to the field of coal mining technology, specifically a method for constructing artificial water-conducting channels by pulse fracturing of boreholes for draining water from the roof aquifer. Background Technology

[0002] Draining water from aquifers in coal mine roofs is a common and challenging problem. As the focus of coal mining gradually shifts to the central and western regions, and mining depths increase, most mining areas have low levels of hydrogeological exploration. Geophysical drilling and other methods for exploring roof aquifer characteristics often prove difficult and inaccurate, failing to provide precise information on the distribution and continuity of aquifer areas. This lack of effective technical support for the prevention and control of roof water hazards during mining makes the drainage of aquifers in mine roofs even more complex and challenging. This is especially true in deep mines, where the water pressure in roof aquifers is higher, water level fluctuations are more drastic, and groundwater permeability is enhanced, making the problem of water hazards from roof aquifers even more challenging.

[0003] If roof aquifers are not properly predicted, evaluated, and treated, they will severely impact mine construction and mining processes. Currently, comprehensive theoretical foundations have been established in areas such as roof water hazard assessment, aquifer water-bearing capacity evaluation, and hydrogeological parameter calculation, enabling relatively accurate prediction and evaluation of roof water hazards. However, for complex geological conditions such as good water-bearing capacity of sandstone fissures in coal seams, heterogeneous aquifer and water conductivity, strong localization, and poor rock permeability, geophysical exploration accuracy is insufficient to meet engineering requirements. Pre-drainage through boreholes has a certain degree of blindness, while draining roof sandstone fissure water through intensified borehole drilling involves large engineering workloads and long construction periods. Traditional treatment methods such as pre-drainage through boreholes, grouting reinforcement, and borehole sealing often have limited effectiveness, failing to fully drain and control roof sandstone water. Large-area roof water seepage may still occur during mining, impacting normal mine operations and safe production.

[0004] Especially in geological environments where the coal seam roof has good water-bearing properties but uneven water conductivity and water content, resulting in strong localization, the water exploration and drainage method of pre-drainage through underground drilling is not effective in draining water from sandstone fissures in the roof. Currently, the exploration and drainage of sandstone water in coal seams with good water-bearing properties but uneven water conductivity and water content mainly relies on pre-drainage through underground drilling. However, sandstone permeability is controlled by the in-situ sandstone mass structure. Under normal conditions, dense and intact rock masses have poor permeability, resulting in poor drilling drainage effects. This can lead to large-area roof water seepage during working face mining, affecting normal operations and safe production. Therefore, there is an urgent need to solve the problem of efficient drainage of sandstone water in coal seams with good water-bearing properties but uneven water conductivity and water content.

[0005] In view of this, the present invention is hereby proposed.

[0006] Summary of the Invention

[0007] Ensuring adequate drainage in the mine is fundamental to successful mining and operational safety. Before mining begins, a number of exploratory boreholes are typically installed to effectively control roof water hazards and ensure safe mining operations. These boreholes serve both as advance exploration points and drainage points. To fully drain water-rich areas from the roof, a drainage borehole layout plan must be designed based on the hydrogeological characteristics of the mining area, including the identified water-bearing zones, water-rich areas, and their continuity. Drainage boreholes are generally classified into two types: cross-layer straight boreholes and directional long boreholes.

[0008] For complex geological conditions characterized by high water-bearing capacity of sandstone fissures in the roof, discontinuous aquifers, and poor permeability of dense, intact sandstone masses, drilling boreholes to fully drain water from all discontinuous aquifers would be not only a massive undertaking but also difficult to guarantee complete drainage of the sandstone fissure water. The core solution lies in arranging drainage boreholes and employing technical means to pre-create artificial water-conducting channels within the sandstone fissure aquifers through these boreholes. This improves the permeability of the dense, intact sandstone mass. The artificial water-conducting channels formed by these boreholes connect discontinuous aquifers and water-rich areas, guiding the sandstone fissure water from the roof to the drainage boreholes, thus achieving effective drainage and expanding the drainage area of ​​each borehole.

[0009] The number of boreholes typically used for drilling is relatively small, making it difficult to drain the large and discontinuous amount of fracture water in the roof sandstone. Therefore, to effectively drain the fracture water in the roof sandstone, it is necessary to design and drill additional drainage boreholes. By arranging inclined drainage boreholes with alternating long and short holes and fracturing, not only can all water-bearing areas within the radius of the fracture be connected through a single hole, effectively increasing the drainage area of ​​the roof, but also, by arranging the drainage boreholes in an inclined manner, it can be ensured that during the mining process, the roof fracture water that has not been fully drained will flow along the mining-induced fractures to the drainage boreholes, achieving advance water release from the working face.

[0010] Hydraulic fracturing refers to the injection of high-pressure fluid (water, gas, etc.) into a borehole, causing the borehole wall to fracture and propagate under fluid-structure interaction. Pre-fracturing the roof of the rock through drainage boreholes creates fractures in the sandstone aquifer, constructing artificial water channels, and is an effective technique for efficiently draining water from sandstone fissures. Conventional hydraulic fracturing pumps have a constant injection rate, and the propagation direction of hydraulic fractures is controlled by the three-dimensional geostress field, extending perpendicular to the direction of the minimum principal stress, resulting in a small number of hydraulic fractures. Pulse pump fracturing utilizes a high-pressure pulse pump to output high-frequency pulsed water, impacting the borehole wall and causing fatigue damage to the rock. This overcomes the influence of the geostress field on the initiation and propagation direction of hydraulic fractures, forming a dense network of fractures within the rock.

[0011] Therefore, a method for constructing artificial water channels using pulse fracturing of drainage boreholes in the roof aquifer is proposed. This method not only avoids the need for excessive drainage boreholes and significantly improves the drainage efficiency of exploration and drainage boreholes, but also plays a role in pre-drainage during mining. Through this method, even under unfavorable geological conditions, mine water hazards can be effectively controlled, ensuring safe production in the mine.

[0012] The purpose of this invention is to provide a method for constructing artificial water channels by pulse fracturing of aquifer drainage boreholes in the top plate, so as to solve the problems mentioned in the background art.

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] The method for constructing artificial water-conducting channels by pulse fracturing in the top aquifer for draining water includes the following steps:

[0015] S100. Collect hydrogeological information of the mining area and explore the specific stratigraphic position and water volume of the sandstone fissure aquifer in the roof.

[0016] S200. Take rock samples from the sandstone fracture aquifer in the top plate and conduct segmented pulse fracturing simulation experiments. By analyzing the relationship between pulse pressure peak value, pulse frequency, segment length, segment interval length, fracturing time and fracture development, determine the optimal pulse frequency, pulse pressure peak value, segment length, segment interval length and fracturing time for segmented pulse fracturing in the drainage operation area.

[0017] S300. Based on the fracture development pattern in the segmented pulse fracturing simulation experiment and the specific strata and water volume of the sandstone fracture aquifer in the top plate, determine the drainage borehole layout parameters, drainage borehole layout form and segmented pulse fracturing parameters.

[0018] S400. Drilling is carried out according to the drainage borehole layout parameters and drainage borehole layout form. After the drilling is completed, the site is explored to determine the placement position of the pulse fracturing equipment.

[0019] S500. After the completion of the drainage borehole construction, install a water-stop sleeve and matching borehole valve to prevent excessive water output from the borehole after fracturing connects multiple water-bearing areas. Connect the borehole valve to an external flow meter to monitor the return water volume at the borehole. Determine whether the artificial water channel formed by pulse fracturing connects the roof fissure water by the difference between the pulse pump injection volume and the rock stratum filtration loss volume and the return water volume at the borehole. Estimate the water volume of the roof water-bearing area connected by the artificial water channel.

[0020] Before fracturing operations, artificial water diversion channels are set up in the roadway near the opening of the water drainage borehole to prevent excessive water output from the borehole after fracturing connects multiple water-bearing areas; after the pulse fracturing equipment is transported to the operation position, the quantity and integrity of the equipment are checked and the equipment is connected.

[0021] After the S700 pulse fracturing equipment connection inspection is completed, the drilling rig sequentially sends the shut-off valve, near-bottom packer, check valve, near-orifice packer, and high-pressure sealing drill to the designed first-stage fracturing position to begin the segmented pulse fracturing operation. After the first-stage pulse fracturing is completed, the drilling rig withdraws part of the high-pressure sealing drill rod. The total length of the withdrawn high-pressure sealing drill rod should be equal to the segment interval length. Then, the next stage of pulse fracturing is carried out. The segmented pulse fracturing of a single hole repeats the above operation until all designed fracturing stages within a single hole are completed.

[0022] After the S800 pulse fracturing operation is completed, shut down the pulse fracturing pump, open the pressure relief valve in the pipeline to release the residual fracturing fluid in the pipeline, and wait for the pressure in the pipeline to drop to 0. Then, sequentially push out the high-pressure sealing drill pipe, near-hole packer, check valve, near-hole bottom packer, shut-off valve and other equipment and check their integrity. Repeat the above pulse fracturing process to complete the segmented pulse fracturing of all boreholes in sequence.

[0023] S900 After completing the pulse fracturing operation, monitor and count the return water volume of the drainage borehole, evaluate the effect of pulse fracturing on improving the drainage of water in the sandstone fracture aquifer in the top plate, and if the water output of the drainage borehole is too large, adjust the ball stop valve at the borehole opening in time to control the water output of the drainage borehole.

[0024] Preferably, in step S100:

[0025] The hydrogeological information of the mining area was collected through hydrogeological surveys, three-dimensional seismic exploration, and spatial analysis using geographic information systems.

[0026] The specific location and water volume of the aquifer in the fractured sandstone of the top plate were determined through advance exploration by setting up several exploratory boreholes in the mining area.

[0027] Preferably, in step S300:

[0028] The parameters for the layout of drainage boreholes include borehole length, inclination angle, spacing, azimuth angle, and diameter;

[0029] The endpoint of the drainage borehole layout is located at the geometric center of the geometric figure formed by connecting the center points of multiple discontinuous water-bearing areas that can be included in the radiation area of ​​the pulse fracturing fracture development.

[0030] Preferably, in step S300:

[0031] The spacing of the drainage boreholes is designed based on the distribution and continuity of the water-bearing area;

[0032] If the water-bearing area is evenly distributed and has good continuity, the spacing between drainage boreholes should be 30–50 m.

[0033] If the water-bearing areas are unevenly distributed and lack continuity, the drainage boreholes should be arranged so that the water-bearing areas within the fracture development radiation area can be fully connected after pulse fracturing of a single borehole. The spacing between adjacent drainage boreholes should ensure that all discontinuous water-bearing areas between two adjacent boreholes are within the fracture development radiation range, in order to prevent excessive water discharge from the borehole after fracturing and connecting multiple water-bearing areas.

[0034] Preferably, in step S300:

[0035] The azimuth angle of the drainage borehole is offset by 30° to 60° towards the working face cut, so that the drainage borehole can drain water in advance during the working face mining process; the diameter of the drainage borehole is 94mm to 120mm; the single-stage fracturing time is 20 to 60min.

[0036] Preferably, in step S300:

[0037] The arrangement of the drainage boreholes includes a through-layer straight borehole arrangement, a directional long borehole arrangement, and a combination of through-layer straight boreholes and directional long boreholes.

[0038] Preferably, in step S300:

[0039] The perforated arrangement includes fan-shaped perforations, parallel perforations, and a combination of fan-shaped and parallel perforations.

[0040] Preferably, in step S300:

[0041] The fan-shaped borehole layout refers to arranging multiple boreholes in a drilling site, with the boreholes distributed in a fan shape. The fan-shaped borehole layout method has the advantages of fewer drilling rig movements and higher drilling efficiency, and is suitable for draining water in local discontinuous water-bearing areas with relatively concentrated distribution.

[0042] Parallel borehole layout refers to arranging multiple sets of alternating long and short boreholes in the inclined working faces of the two roadways of a coal mining face. The long and short boreholes are parallel to each other in planar projection. The advantages of parallel boreholes are reduced construction volume and shorter operation time, and they can also play a role in pre-drainage and water diversion during face mining. The alternating arrangement of long and short boreholes is used to reduce the blind zone in aquifer pulse fracturing.

[0043] Preferably, in step S300:

[0044] Directional long borehole layout refers to the deployment of long directional boreholes (over 200m) in the working face roadway using a directional drilling rig into the sandstone aquifer in the coal seam roof. The boreholes run parallel to the working face advance direction. Because the majority of the borehole trajectory lies within the roof sandstone aquifer, segmented pulse fracturing within these boreholes allows for extensive aquifer modification and the creation of numerous artificial water-conducting fractures. Therefore, each borehole provides a large drainage coverage area. Furthermore, the parallel borehole direction also facilitates pre-drainage during working face extraction.

[0045] Preferably, in step S300:

[0046] The combined arrangement of cross-layer straight holes and directional long boreholes refers to the arrangement of two types of boreholes in the working roadway: cross-layer straight holes and directional long boreholes. First, directional long boreholes are used to create large-scale artificial water-conducting fractures through segmented pulse fracturing to drain water from the roof fracture aquifers. Then, for aquifer areas not radiated by the directional long boreholes or for aquifers with strong localization, cross-layer straight holes are used for localized water drainage as a supplementary guarantee, reducing blind spots of artificial water-conducting fractures and more fully connecting discontinuous aquifer areas in the roof.

[0047] Preferably, in step S600:

[0048] The connection equipment specifically includes: a water tank connected to the water supply pipeline via a water tank supply hose to supply liquid to the water tank; a pulse fracturing pump connected to the water tank via a pulse pump return hose and a supply hose to supply liquid to the pulse fracturing pump; a pulse fracturing pump connected to a high-pressure hose to output pulse fracturing water and inject it into the borehole; a tee joint and a pressure relief valve connected between the high-pressure hoses to relieve water pressure in the pipeline; a pressure sensor and a flow sensor connected to the high-pressure hose to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; a pressure sensor connected to the fracturing control instrument via a pressure sensor signal transmission line, and a flow sensor connected to the fracturing control instrument via a flow sensor signal line, to transmit the monitored pulse pressure and flow rate signals in the pipeline to the fracturing control instrument, display the pulse pressure and flow rate curves in real time, and store the data.

[0049] Preferably, the connection between the orifice ball stop valve and the return flow meter is achieved by using a steel strap buckle to fix the return flow meter to the roadway side, and the return flow meter is connected to the orifice drainage hose, which is then connected to the drainage ditch of the two roadways.

[0050] Preferably, in step S900:

[0051] Monitoring and evaluation of operational effectiveness includes monitoring and evaluating the effectiveness of pulse fracturing in fractured aquifers in the roof and monitoring the effectiveness of drainage.

[0052] Monitoring of the effectiveness of pulse fracturing in fractured aquifers in the top plate includes monitoring the number and distribution of pulse fracturing fractures on the borehole wall of the drainage borehole, and monitoring the propagation range of pulse fracturing fractures.

[0053] The monitoring of water drainage effect mainly includes the statistics of borehole water return after pulse fracturing and the statistics of water saturation on the roadway roof during normal mining.

[0054] Preferably, in step S900:

[0055] The monitoring of the propagation range of pulse fracturing fractures in drainage boreholes is carried out by using adjacent boreholes as observation holes. If water is seen or the water flow increases in adjacent boreholes during the pulse fracturing process, it indicates that the pulse fracturing fractures have propagated to the adjacent boreholes.

[0056] The number and distribution pattern of pulse fracturing fractures in the borehole wall of the water drainage borehole were monitored by a borehole inspection instrument. After the drilling was completed, the borehole wall morphology of the fracturing section was observed with a borehole inspection instrument before pulse fracturing. After pulse fracturing, the borehole wall of the fracturing section was observed again. The number and distribution pattern of pulse fracturing fractures in the water drainage borehole were compared and analyzed.

[0057] Preferably, in step S900:

[0058] The statistics on borehole return water volume after pulse fracturing refer to monitoring the pump flow rate during fracturing using a flow sensor, calculating the rock stratum filtration loss based on indoor fracturing simulation experiments conducted in the laboratory, monitoring the borehole return water volume after pulse fracturing using a borehole return water flow meter, and determining whether the artificial water channel formed by pulse fracturing connects the roof fracture water by the difference between the pulse pump water volume, the rock stratum filtration loss, and the borehole return water volume, and estimating the water volume in the roof aquifer area connected by the artificial water channel.

[0059] The statistics on water seepage from the roof of the roadway during normal mining operations refer to the observation and recording of water seepage from the roof before and after fracturing, as well as the water seepage from the roof during mining operations. The macroscopic phenomena are used to visually evaluate the effect of pulse fracturing on promoting the drainage of water in the water-bearing areas of the sandstone fractures in the roof.

[0060] Compared with existing technologies, the method for constructing artificial water channels through pulse fracturing of drainage boreholes in the roof aquifer proposed in this invention not only avoids the need for excessive drainage boreholes and significantly improves the drainage efficiency of exploration and drainage boreholes, but also plays a role in pre-drainage during mining. This method effectively controls mine water hazards and ensures safe mine production, even under unfavorable geological conditions.

[0061] Meanwhile, the pulse fracturing of the water-draining borehole in the roof fracture aquifer has the dual function of water drainage and mine pressure control. It can not only promote the water drainage effect in the water-bearing area of ​​the roof sandstone fracture, but also pre-fracture the coal seam roof, reduce the collapse step of the roof during the mining process, and reduce the mine pressure manifestation during the mining period.

[0062] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0063] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 is an overall schematic diagram of a method for constructing an artificial water-conducting channel by pulse fracturing of a top plate aquifer for draining water, provided by an embodiment of the present invention.

[0065] Figure 2 is a plan view of segmented pulse fracturing of parallel straight boreholes through the top plate aquifer in a method for constructing an artificial water-conducting channel by pulse fracturing of a top plate aquifer for draining water provided in an embodiment of the present invention.

[0066] Figure 3 is a cross-sectional view of segmented pulse fracturing of parallel straight boreholes in the top plate aquifer, which is part of a method for constructing an artificial water channel by pulse fracturing of a top plate aquifer for draining water provided in an embodiment of the present invention.

[0067] Figure 4 is a plan view of segmented pulse fracturing of a cross-layer fan-shaped straight borehole in a method for constructing an artificial water-conducting channel in a top plate aquifer according to an embodiment of the present invention.

[0068] Figure 5 is a cross-sectional view of segmented pulse fracturing of a cross-layer fan-shaped straight borehole in a method for constructing an artificial water-conducting channel in a top plate aquifer according to an embodiment of the present invention.

[0069] Figure 6 is a plan view of the segmented pulse fracturing of a directional long borehole in the top plate aquifer in a method for constructing an artificial water-conducting channel by pulse fracturing of a top plate aquifer for water drainage provided in an embodiment of the present invention.

[0070] Figure 7 is a cross-sectional view of segmented pulse fracturing of a directional long borehole in the top plate aquifer, which is part of a method for constructing an artificial water-conducting channel by pulse fracturing of a top plate aquifer for draining water provided in an embodiment of the present invention.

[0071] Figure 8 is a plan view of the segmented pulse fracturing of the top plate aquifer combined with the cross-layer straight hole and the directional long hole in a method for constructing an artificial water channel by pulse fracturing of the top plate aquifer according to an embodiment of the present invention.

[0072] Figure 9 is a cross-sectional view of the combination of through-layer straight holes and directional long holes in the top plate aquifer for segmented pulse fracturing in a method for constructing an artificial water-conducting channel by pulse fracturing of a top plate aquifer according to an embodiment of the present invention.

[0073] Figure 10 is a diagram of segmented pulse fracturing of a direct borehole through a layer in an old void area of ​​the top plate, which is part of a method for constructing an artificial water channel by pulse fracturing of a borehole for draining water in a top plate aquifer according to an embodiment of the present invention.

[0074] The diagram illustrates the following: 1. Sandstone fissure aquifer in the roof; 2. Coal seam; 3. Discontinuous aquifer zone; 4. Pulse fracturing pump; 5. Pulse pump water supply hose; 6. Water tank; 7. Water tank water supply hose; 8. Water supply pipeline; 9. High-pressure hose; 10. First tee connector; 11. Pressure relief valve; 12. Pressure sensor; 13. Pressure sensor signal transmission line; 14. Flow sensor; 15. Flow sensor signal transmission line; 16. Fracturing control instrument; 17. Orifice ball stop valve; 18. Water stop sleeve. 9. High-pressure sealed drill rod; 20. Near-hole packer; 21. Check valve; 22. Near-hole bottom packer; 23. Shut-off valve; 24. Artificial water diversion channel; 25. Drainage hose at the borehole opening; 26. Steel strip buckle; 27. Return water flow meter; 28. Drainage ditch; 29. ​​Parallel long borehole; 30. Parallel short borehole; 31. Return airway; 32. Transport roadway; 33. Working face cut; 34. Fan-shaped borehole; 35. Directional long borehole; 36. Old mine goaf; 37. Goaf water accumulation. Detailed Implementation

[0075] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0076] Example 1: As shown in Figures 1-3, geophysical exploration at a certain mine face revealed a discontinuous strip-shaped water-bearing zone overlying the coal seam. This water-bearing zone was approximately 200-300m deep, with a dip angle of 6° and an average thickness of 1.9m. During tunnel excavation, significant water seepage occurred from the roof. Previous geophysical exploration in the mine area involved drilling water exploration holes to drain the roof water. However, due to the unevenness of the rock strata, drainage through these holes alone was inefficient and time-consuming. Furthermore, the water output from adjacent holes was uneven, with one hole yielding approximately 17m³ of water. 3 / h, the water output of the adjacent drain hole is approximately 3m³ / h. 3 / h.

[0077] To fully drain the fissure water in the roof sandstone, reduce water seepage in the roadway during working face mining, and ensure normal operation and safe production, this invention provides a method for constructing artificial water channels through pulse fracturing boreholes in the roof aquifer. This method utilizes segmented pulse fracturing with parallel straight boreholes through the roof aquifer to construct artificial water channels, solving the problem of low efficiency in conventional water drainage measures for roof sandstone fissure aquifers. The specific steps are as follows:

[0078] Step 1: Collect hydrogeological information of the mining area through hydrogeological surveys, 3D seismic exploration, and geographic information system (GIS) spatial analysis. This mainly includes the distribution and strata of the sandstone fissure aquifer 1 in the roof and the permeability of the rock strata. Set up several water exploration boreholes in the mining area for advanced exploration to obtain the specific strata and water volume of the sandstone fissure aquifer 1 in the roof, and at the same time for drainage.

[0079] Step 2: Take rock samples from the sandstone fracture aquifer 1 in the top plate and transport them to the laboratory for indoor segmented pulse fracturing simulation experiments. Study the relationship between pulse pressure peak value, pulse frequency, segment length, segment interval length, fracturing time and fracture development to determine the optimal pulse frequency, pulse pressure peak value, segment length, segment interval length and fracturing time for segmented pulse fracturing in the drainage operation area, and provide a basis for constructing artificial water diversion channels by pulse fracturing in drainage boreholes.

[0080] Step 3: Based on the fracture development patterns and aquifer distribution obtained from indoor segmented pulse fracturing simulation experiments, design a drainage borehole layout scheme and a segmented pulse fracturing scheme. In the return airway 3 and transport airway 32, design alternating long and short parallel boreholes 29 and 30 for segmented pulse fracturing. The borehole diameter is 94mm. Long borehole 29 is 91m long with an elevation angle of 7.5° and a 60° inclination towards the working face. Short borehole 30 is 47m long with an elevation angle of 12.8° and a 60° inclination towards the working face. The borehole spacing is 30m. The alternating long and short borehole arrangement is to reduce the blind zone in the aquifer pulse fracturing. The boreholes' inclination towards the working face allows for pre-drainage during working face extraction.

[0081] Step 4: After the drilling layout plan is determined, construct parallel long borehole 29 and parallel short borehole 30. After the drilling is completed, explore the site to determine the placement of the pulse fracturing pump 4 and water tank 6.

[0082] Step 5: Install a water-stop sleeve 18 and a matching orifice ball-shaped water-stop valve 17 at the completed borehole opening to prevent excessive water flow from the borehole after fracturing connects multiple water-bearing areas. Connect a backflow meter 27 to the orifice valve to monitor the backflow volume. Determine whether the artificial water channel formed by pulse fracturing connects to the roof fissure water by comparing the pulse pump injection volume and the rock strata filtration loss with the orifice backflow volume. Estimate the water volume in the roof water-bearing area connected by the artificial water channel.

[0083] Step 6: Before fracturing operations, drainage ditches 28 are installed in the roadways near the fracturing borehole, namely the return airway 3 and the transport roadway 32, to prevent water accumulation in the roadways caused by excessive water discharge from the borehole during fracturing, which could scour the working face. After the pulse fracturing pump 4 and water tank 6 are transported to the operation position, the quantity and integrity of the equipment are checked, and the equipment is connected. The water tank 6 is connected to the water supply pipeline 8 through the water tank supply hose 7 to supply liquid to the water tank; the pulse fracturing pump 4 is connected to the water tank 6 through the pulse pump return hose and the water supply hose 5 to supply liquid to the pulse fracturing pump 4; the pulse fracturing pump 4 is connected to the high-pressure hose 9 to output pulse fracturing water for injection into the borehole; the high-pressure hose 9 is connected to a first tee joint 10 and a pressure relief valve 11 to relieve the water pressure in the pipeline; the pressure sensor 12 and the flow sensor 14 are connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing. The pressure sensor signal transmission line 13 is connected to the fracturing control instrument 16, and the flow sensor 14 is connected to the fracturing control instrument 16 through the flow sensor signal line 15. It is used to transmit the pulse pressure and flow signals in the pipeline to the fracturing control instrument, display the pulse pressure and flow curves in real time, and store the data. The orifice ball stop valve 17 and the return water flow meter 27 are connected through the orifice drainage hose 25. The return water flow meter 27 is fixed to the roadway side with steel strap buckle 26. The return water flow meter 27 is connected to the orifice drainage hose 25, and the orifice drainage hose 25 is connected to the drainage ditch 28 of the two roadways.

[0084] Step 7: After the connection and inspection of the pulse fracturing pump 4, pulse pump water supply hose 5, water tank 6, and water tank water supply hose 7 are completed, the drill rig is used to sequentially send the shut-off valve 23, near-bottom packer 22, one-way valve 21, near-orifice packer 20, and high-pressure sealing drill 19 to the designed first-stage fracturing position to start the segmented pulse fracturing operation. Among them, the long borehole is fracturing 3 stages and the short borehole is fracturing 2 stages. The fracturing time for a single stage is 40 min to 50 min. After the first stage of pulse fracturing is completed, the drill rig is used to withdraw part of the high-pressure sealing drill rod. The total length of the withdrawn high-pressure sealing drill rod should be equal to the segment interval length. Then, the next stage of pulse fracturing is carried out. The segmented pulse fracturing of a single hole repeats the above operation until all the designed fracturing stages in a single hole are completed.

[0085] Step 8: After the pulse fracturing operation is completed, the high-pressure sealing drill pipe 19, near-hole packer 20, one-way valve 21, near-hole bottom packer 22, and shut-off valve 23 are sequentially pulled out and their integrity is checked. Then, the above pulse fracturing process is repeated to complete the segmented pulse fracturing of all boreholes.

[0086] Step 9: After completing the pulse fracturing operation, monitor and statistically analyze the return water volume from the drainage borehole to evaluate the effect of pulse fracturing on improving the drainage of water from the fractured sandstone aquifer in the roof. Specifically, monitor the changes in the return water flow meter 27 at the borehole opening. One monitoring cycle is 7 days. Compare the return water volume recorded by the return water flow meter 27 after fracturing with the injection water volume recorded by the pulse fracturing control instrument 16 to estimate the amount of roof water discharged through artificial water diversion constructed by pulse fracturing within one cycle.

[0087] If the water output from the drainage borehole is too high, the ball stop valve 17 at the borehole opening should be adjusted in time to control the water output from the drainage borehole and achieve fully controllable drainage.

[0088] As shown in Figures 1 and 4-5, there are a large number of low-lying areas in the roof of a coal seam in a certain mine. The water accumulation is discontinuous, highly localized, and unevenly distributed across different strata. During the mining process, the roof may become unstable due to mining activity, and the accumulated water in the low-lying areas may be released suddenly, potentially affecting the working area of ​​the coal face below.

[0089] Example 2: Since the complete distribution of low-lying areas is difficult to fully investigate using geophysical exploration and other methods, in order to effectively drain water accumulated in the roof low-lying areas, reduce roof water inflow during working face mining, and ensure normal operation and safe production, this embodiment of the invention provides a method for constructing artificial water-conducting channels through pulse fracturing of boreholes in the roof aquifer. This method uses segmented pulse fracturing of cross-layer fan-shaped straight boreholes in the roof low-lying aquifer to construct artificial water-conducting channels, solving the problem of low efficiency in conventional water drainage measures in roof low-lying aquifers. The specific steps are as follows:

[0090] Step 1: Collect hydrogeological information of the mining area through hydrogeological surveys, 3D seismic exploration, and geographic information system (GIS) spatial analysis. This mainly includes the distribution and strata of the top sandstone fissure aquifer 1 (low-lying water accumulation area) and the permeability of the rock strata. Set up several water exploration boreholes in the mining area for advanced exploration to obtain the specific strata and water volume of the top sandstone fissure aquifer 1 (low-lying water accumulation area), and at the same time, for water drainage.

[0091] Step 2: Take rock samples from the sandstone fracture aquifer 1 in the top plate and transport them to the laboratory for indoor segmented pulse fracturing simulation experiments. Study the relationship between pulse pressure peak value, pulse frequency, segment length, segment interval length, fracturing time and fracture development to determine the optimal pulse frequency, pulse pressure peak value, segment length, segment interval length and fracturing time for segmented pulse fracturing in the drainage operation area, and provide a basis for constructing artificial water diversion channels by pulse fracturing in drainage boreholes.

[0092] Step 3: Based on the fracture development patterns and water-bearing area distribution obtained from the indoor segmented pulse fracturing simulation experiment, design the drainage borehole layout scheme and segmented pulse fracturing scheme. A set of fan-shaped boreholes 34 with a diameter of 94mm are designed within the working face roadway drilling area for segmented pulse fracturing. The fan-shaped boreholes 34 are arranged symmetrically on both wings, with the plane containing the middle long and short boreholes as the symmetrical plane. The middle long borehole is 101m long with an elevation angle of 9° and is arranged parallel to the working face cut-in 33. The middle section borehole is 69m long with an elevation angle of 12° and is also arranged parallel to the working face cut-in 33. The right wing short borehole is inclined at 45° towards the working face, with a borehole length of 74m and an elevation angle of 13°. The right wing long borehole is inclined at 70° towards the working face, with a borehole length of 89m and an elevation angle of 11°. The left wing boreholes are arranged symmetrically with the right wing boreholes, with the plane containing the middle long and short boreholes as the symmetrical plane. The distance between adjacent sets of fan-shaped boreholes is 60m. The fan-shaped hole layout method can effectively connect low-lying water with strong locality and uneven strata, and has the advantages of fewer drilling rig moves and high drilling efficiency. It is suitable for draining water in local discontinuous water-bearing areas with relatively concentrated distribution.

[0093] Step 4: After the drilling layout plan is determined, fan-shaped borehole 34 is constructed. After the drilling is completed, the site is surveyed to determine the placement of the pulse fracturing pump 4 and the water tank 6.

[0094] Step 5: Install a water-stop sleeve 18 and a matching orifice ball-shaped water-stop valve 17 at the completed borehole opening to prevent excessive water flow from the opening after fracturing connects multiple water-bearing areas. Connect an external flow meter 27 to the orifice valve to monitor the return water volume. Determine whether the artificial water channel formed by pulse fracturing connects to the roof fissure water by comparing the pulse pump injection volume and the rock strata filtration loss with the orifice return water volume. Estimate the water accumulation in the low-lying areas of the roof connected by the artificial water channel.

[0095] Step 6: Before fracturing operations, drainage ditches 28 are installed in the roadways near the fracturing borehole, namely the return airway 3 and the transport roadway 32, to prevent water accumulation in the roadways caused by excessive water discharge from the borehole during fracturing, which could scour the working face. After the pulse fracturing pump 4 and water tank 6 are transported to the operation position, the quantity and integrity of the equipment are checked, and the equipment is connected. The water tank 6 is connected to the water supply pipeline 8 through the water tank supply hose 7 to supply liquid to the water tank; the pulse fracturing pump 4 is connected to the water tank 6 through the pulse pump return hose and the water supply hose 5 to supply liquid to the pulse fracturing pump 4; the pulse fracturing pump 4 is connected to the high-pressure hose 9 to output pulse fracturing water for injection into the borehole; the high-pressure hose 9 is connected to a first tee joint 10 and a pressure relief valve 11 to relieve the water pressure in the pipeline; the pressure sensor 12 and the flow sensor 14 are connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing. The pressure sensor signal transmission line 13 is connected to the fracturing control instrument 16, and the flow sensor 14 is connected to the fracturing control instrument 16 through the flow sensor signal line 15. It is used to transmit the pulse pressure and flow signals in the pipeline to the fracturing control instrument, display the pulse pressure and flow curves in real time, and store the data. The orifice ball stop valve 17 and the return water flow meter 27 are connected through the orifice drainage hose 25. The return water flow meter 27 is fixed to the roadway side with steel strap buckle 26. The return water flow meter 27 is connected to the orifice drainage hose 25, and the orifice drainage hose 25 is connected to the drainage ditch 28 of the two roadways.

[0096] Step 7: After the connection and inspection of the pulse fracturing pump 4, pulse pump water supply hose 5, water tank 6, and water tank water supply hose 7 are completed, the drill rig is used to sequentially send the shut-off valve 23, near-bottom packer 22, one-way valve 21, near-orifice packer 20, and high-pressure sealing drill 19 to the designed first-stage fracturing position to start the segmented pulse fracturing operation. Among them, the long borehole is fracturing 3 stages and the short borehole is fracturing 2 stages. The fracturing time for a single stage is 40 min to 50 min. After the first stage of pulse fracturing is completed, the drill rig is used to withdraw part of the high-pressure sealing drill rod. The total length of the withdrawn high-pressure sealing drill rod should be equal to the segment interval length. Then, the next stage of pulse fracturing is carried out. The segmented pulse fracturing of a single hole repeats the above operation until all the designed fracturing stages in a single hole are completed.

[0097] Step 8: After the pulse fracturing operation is completed, the high-pressure sealing drill pipe 19, near-hole packer 20, one-way valve 21, near-hole bottom packer 22, and shut-off valve 23 are sequentially pulled out and their integrity is checked. Then, the above pulse fracturing process is repeated to complete the segmented pulse fracturing of all boreholes.

[0098] Step 9: After completing the pulse fracturing operation, monitor and statistically analyze the return water volume from the drainage borehole to evaluate the effect of pulse fracturing on improving drainage in the roof depression area. Specifically, monitor the changes in the return water flow meter 27 at the borehole opening. One monitoring cycle is 7 days. Compare the return water volume recorded by the return water flow meter 27 after fracturing with the injection water volume recorded by the pulse fracturing control instrument 16 to estimate the water content in the roof depression area discharged by artificial water diversion through pulse fracturing within one cycle.

[0099] If the water output from the drainage borehole is too high, the ball stop valve 17 at the borehole opening should be adjusted in time to control the water output from the drainage borehole and achieve fully controllable drainage.

[0100] Example 3: As shown in Figures 1 and 6-7, the average thickness of the coal seam in a certain mining area is 2.8m. The immediate roof is mudstone with an average thickness of 2.5m, and the upper roof is fine sandstone with an average thickness of 11.4m. The roadway is excavated along the roof of the coal seam. The water content is abundant and stable about 40m above the roof, mainly from the fissure water in the roof sandstone, which has good water-bearing capacity. However, during the roadway excavation, the roof exhibits discontinuous water seepage, and a clear dry-wet boundary line can be observed. The adjacent 1m anchor cables installed in the roadway also show discontinuous water seepage, indicating that the water-bearing area of ​​the mining area has uneven conductivity and water content, strong localization, and poor permeability of the dense sandstone. The previous geophysical exploration cannot effectively reflect the water-bearing area of ​​the roof. The exploratory boreholes alone cannot effectively drain the roof water. During the working face mining, large-scale roof water seepage may occur, affecting normal operation and safe production.

[0101] To address this problem, this invention provides a method for constructing artificial water-conducting channels using pulse fracturing through directional long boreholes in the roof aquifer. This method employs segmented pulse fracturing through directional long boreholes in the roof aquifer to construct artificial water-conducting channels, thereby fully draining water from the roof sandstone. The specific steps are as follows:

[0102] Step 1: Collect hydrogeological information of the mining area through hydrogeological surveys, 3D seismic exploration, and geographic information system (GIS) spatial analysis. This mainly includes the distribution and strata of the sandstone fissure aquifer 1 in the roof and the permeability of the rock strata. Set up several water exploration boreholes in the mining area for advanced exploration to obtain the specific strata and water volume of the sandstone fissure aquifer 1 in the roof, and at the same time for drainage.

[0103] Step 2: Take rock samples from the sandstone fracture aquifer 1 in the top plate and transport them to the laboratory for indoor segmented pulse fracturing simulation experiments. Study the relationship between pulse pressure peak value, pulse frequency, segment length, segment interval length, fracturing time and fracture development to determine the optimal pulse frequency, pulse pressure peak value, segment length, segment interval length and fracturing time for segmented pulse fracturing in the drainage operation area, and provide a basis for constructing artificial water diversion channels by pulse fracturing in drainage boreholes.

[0104] Step 3: Based on the fracture development patterns and water-bearing area distribution obtained from the indoor segmented pulse fracturing simulation experiment, design the drainage borehole layout scheme and the segmented pulse fracturing scheme. A set of directional long boreholes (35mm diameter) is designed within the working face roadway drilling site for segmented pulse fracturing, including three directional long boreholes with a diameter of 120mm and lengths of 549m, 575m, and 574m respectively. The length of a single fracturing zone is 20m, and the interval between adjacent fracturing zones is 10m.

[0105] Step 4: After the drilling layout plan is determined, directional long borehole 35 is drilled. After the drilling is completed, the site is surveyed to determine the placement of the pulse fracturing pump 4 and the water tank 6.

[0106] Step 5: Install a water-stop sleeve 18 and a matching orifice ball-shaped water-stop valve 17 at the completed borehole opening to prevent excessive water flow from the opening after fracturing connects multiple water-bearing areas. Connect an external flow meter 27 to the orifice valve to monitor the return water volume. Determine whether the artificial water channel formed by pulse fracturing connects to the roof fissure water by comparing the pulse pump injection volume and the rock strata filtration loss with the orifice return water volume. Estimate the water accumulation in the low-lying areas of the roof connected by the artificial water channel.

[0107] Step 6: Before fracturing operations, drainage ditches 28 are installed in the roadways near the fracturing borehole, namely the return airway 3 and the transport roadway 32, to prevent water accumulation in the roadways caused by excessive water discharge from the borehole during fracturing, which could scour the working face. After the pulse fracturing pump 4 and water tank 6 are transported to the operation position, the quantity and integrity of the equipment are checked, and the equipment is connected. The water tank 6 is connected to the water supply pipeline 8 through the water tank supply hose 7 to supply liquid to the water tank; the pulse fracturing pump 4 is connected to the water tank 6 through the pulse pump return hose and the water supply hose 5 to supply liquid to the pulse fracturing pump 4; the pulse fracturing pump 4 is connected to the high-pressure hose 9 to output pulse fracturing water for injection into the borehole; the high-pressure hose 9 is connected to a first tee joint 10 and a pressure relief valve 11 to relieve the water pressure in the pipeline; the pressure sensor 12 and the flow sensor 14 are connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing. The pressure sensor signal transmission line 13 is connected to the fracturing control instrument 16, and the flow sensor 14 is connected to the fracturing control instrument 16 through the flow sensor signal line 15. It is used to transmit the pulse pressure and flow signals in the pipeline to the fracturing control instrument, display the pulse pressure and flow curves in real time, and store the data. The orifice ball stop valve 17 and the return water flow meter 27 are connected through the orifice drainage hose 25. The return water flow meter 27 is fixed to the roadway side with steel strap buckle 26. The return water flow meter 27 is connected to the orifice drainage hose 25, and the orifice drainage hose 25 is connected to the drainage ditch 28 of the two roadways.

[0108] Step 7: After the connection and inspection of the pulse fracturing pump 4, pulse pump water supply hose 5, water tank 6, and water tank water supply hose 7 are completed, the drill rig is used to sequentially send the shut-off valve 23, near-bottom packer 22, one-way valve 21, near-orifice packer 20, and high-pressure sealing drill 19 to the designed first-stage fracturing position to start the segmented pulse fracturing operation. Among them, the long borehole is fracturing 3 stages and the short borehole is fracturing 2 stages. The fracturing time for a single stage is 40 min to 50 min. After the first stage of pulse fracturing is completed, the drill rig is used to withdraw part of the high-pressure sealing drill rod. The total length of the withdrawn high-pressure sealing drill rod should be equal to the segment interval length. Then, the next stage of pulse fracturing is carried out. The segmented pulse fracturing of a single hole repeats the above operation until all the designed fracturing stages in a single hole are completed.

[0109] Step 8: After the pulse fracturing operation is completed, the high-pressure sealing drill pipe 19, near-hole packer 20, one-way valve 21, near-hole bottom packer 22, and shut-off valve 23 are sequentially pulled out and their integrity is checked. Then, the above pulse fracturing process is repeated to complete the segmented pulse fracturing of all boreholes.

[0110] Step 9: After completing the pulse fracturing operation, monitor and statistically analyze the return water volume from the drainage borehole to evaluate the effect of pulse fracturing on improving the drainage of water from the top sandstone fracture aquifer. Specifically, monitor the changes in the return water flow meter 27 at the borehole opening. One monitoring cycle is 7 days. Compare the return water volume recorded by the return water flow meter 27 after fracturing with the injection water volume recorded by the pulse fracturing control instrument 16 to estimate the water content of the top sandstone fracture aquifer discharged through artificial water diversion constructed by pulse fracturing within one cycle.

[0111] If the water output from the drainage borehole is too high, the ball stop valve 17 at the borehole opening should be adjusted in time to control the water output from the drainage borehole and achieve fully controllable drainage.

[0112] Because the majority of the directional long borehole trajectory lies within the roof sandstone aquifer, segmented pulse fracturing within these boreholes significantly alters the aquifer's area, creating numerous artificial water-conducting fractures. Consequently, each borehole provides a large drainage coverage area. Furthermore, the borehole's orientation parallel to the working face's advance direction allows for pre-emptive water diversion during face mining.

[0113] Example 4: In a certain mining area, there is water accumulation in the goaf above the coal seam being mined. If the water accumulation in the goaf is not drained through technical means, it may cause serious mine water hazards during coal seam mining, affecting normal operations and safe production.

[0114] Due to the large area and high strata of the old mine goaf, it is difficult to pinpoint the exact location of the water accumulation area through geophysical exploration. To address this issue, this invention provides a method for constructing artificial water channels using pulse fracturing drilling in the roof aquifer. This method involves designing multiple sets of single, inclined, cross-layer boreholes near the old mine goaf to perform segmented pulse fracturing to drain the water accumulated in the goaf. The specific steps are as follows:

[0115] Step 1: Collect hydrogeological information of the mining area through hydrogeological surveys, 3D seismic exploration, and geographic information system (GIS) spatial analysis, mainly including the general distribution of 36 strata and regions in the old mine goaf.

[0116] Step 2: Take rock samples from the strata near the old mine goaf and transport them to the laboratory for indoor segmented pulse fracturing simulation experiments. Study the relationship between pulse pressure peak, pulse frequency, segment length, segment interval length, fracturing time and fracture development to determine the optimal pulse frequency, pulse pressure peak, segment length, segment interval length and fracturing time for segmented pulse fracturing in the drainage operation area, and provide a basis for constructing artificial water diversion channels by pulse fracturing in drainage boreholes.

[0117] Step 3: Based on the fracture development patterns obtained from the indoor segmented pulse fracturing simulation experiment and the distribution of the old mine goaf, design the drainage borehole layout scheme and the segmented pulse fracturing scheme. Multiple sets of single-inclined, parallel, long boreholes (29 in total) are designed within the working face roadway drilling area for segmented pulse fracturing. The borehole diameter is 94mm, the borehole length is 176m, the elevation angle is 21°, and the borehole is inclined at 60° towards the working face.

[0118] Step 4: After the drilling layout plan is determined, parallel long borehole 29 is drilled. After the drilling is completed, the site is surveyed to determine the placement of the pulse fracturing pump 4 and the water tank 6.

[0119] Step 5: Install a water-stop sleeve 18 and a matching orifice ball-shaped water-stop valve 17 at the completed borehole opening to prevent excessive water flow from the opening after fracturing connects multiple water-bearing areas. Connect an external flow meter 27 to the orifice valve to monitor the return water volume. Determine whether the artificial water channel formed by pulse fracturing connects to the roof fissure water by comparing the pulse pump injection volume and the rock strata filtration loss with the orifice return water volume. Estimate the water accumulation in the low-lying areas of the roof connected by the artificial water channel.

[0120] Step 6: Before fracturing operations, drainage ditches 28 are installed in the roadways near the fracturing borehole, namely the return airway 3 and the transport roadway 32, to prevent water accumulation in the roadways caused by excessive water discharge from the borehole during fracturing, which could scour the working face. After the pulse fracturing pump 4 and water tank 6 are transported to the operation position, the quantity and integrity of the equipment are checked, and the equipment is connected. The water tank 6 is connected to the water supply pipeline 8 through the water tank supply hose 7 to supply liquid to the water tank; the pulse fracturing pump 4 is connected to the water tank 6 through the pulse pump return hose and the water supply hose 5 to supply liquid to the pulse fracturing pump 4; the pulse fracturing pump 4 is connected to the high-pressure hose 9 to output pulse fracturing water for injection into the borehole; the high-pressure hose 9 is connected to a first tee joint 10 and a pressure relief valve 11 to relieve the water pressure in the pipeline; the pressure sensor 12 and the flow sensor 14 are connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing. The pressure sensor signal transmission line 13 is connected to the fracturing control instrument 16, and the flow sensor 14 is connected to the fracturing control instrument 16 through the flow sensor signal line 15. It is used to transmit the pulse pressure and flow signals in the pipeline to the fracturing control instrument, display the pulse pressure and flow curves in real time, and store the data. The orifice ball stop valve 17 and the return water flow meter 27 are connected through the orifice drainage hose 25. The return water flow meter 27 is fixed to the roadway side with steel strap buckle 26. The return water flow meter 27 is connected to the orifice drainage hose 25, and the orifice drainage hose 25 is connected to the drainage ditch 28 of the two roadways.

[0121] Step 7: After the connection and inspection of the pulse fracturing pump 4, pulse pump water supply hose 5, water tank 6, and water tank water supply hose 7 are completed, the drill rig is used to sequentially send the shut-off valve 23, near-bottom packer 22, one-way valve 21, near-orifice packer 20, and high-pressure sealing drill 19 to the designed first-stage fracturing position to start the segmented pulse fracturing operation. Among them, the long borehole is fracturing 3 stages and the short borehole is fracturing 2 stages. The fracturing time for a single stage is 40 min to 50 min. After the first stage of pulse fracturing is completed, the drill rig is used to withdraw part of the high-pressure sealing drill rod. The total length of the withdrawn high-pressure sealing drill rod should be equal to the segment interval length. Then, the next stage of pulse fracturing is carried out. The segmented pulse fracturing of a single hole repeats the above operation until all the designed fracturing stages in a single hole are completed.

[0122] Step 8: After the pulse fracturing operation is completed, the high-pressure sealing drill pipe 19, near-hole packer 20, one-way valve 21, near-hole bottom packer 22, and shut-off valve 23 are sequentially pulled out and their integrity is checked. Then, the above pulse fracturing process is repeated to complete the segmented pulse fracturing of all boreholes.

[0123] Step 9: After completing the pulse fracturing operation, monitor and statistically analyze the return water volume from the drainage boreholes to evaluate the effectiveness of pulse fracturing in improving the drainage of water accumulated in the old goaf area of ​​the roof. Specifically, monitor the changes in the return water flow meter 27 at the borehole opening. One monitoring cycle is 7 days. Compare the return water volume recorded by the return water flow meter 27 after fracturing with the injection water volume recorded by the pulse fracturing control instrument 16 to estimate the amount of water accumulated in the old goaf area of ​​the roof discharged through artificial water diversion constructed by pulse fracturing within one cycle.

[0124] If the water output from the drainage borehole is too high, the ball stop valve 17 at the borehole opening should be adjusted in time to control the water output from the drainage borehole and achieve fully controllable drainage.

[0125] Example 5: As shown in Figures 1 and 8-9, this embodiment of the invention provides a method for constructing artificial water-conducting channels using pulse fracturing through boreholes in the top aquifer. This method employs a combination of through-layer straight boreholes and directional long boreholes in the top aquifer for segmented pulse fracturing. The specific steps are as follows:

[0126] Step 1: Collect hydrogeological information of the mining area through hydrogeological surveys, 3D seismic exploration, and geographic information system (GIS) spatial analysis. This mainly includes the distribution and strata of the sandstone fissure aquifer 1 in the roof and the permeability of the rock strata. Set up several water exploration boreholes in the mining area for advanced exploration to obtain the specific strata and water volume of the sandstone fissure aquifer 1 in the roof, and at the same time for drainage.

[0127] Step 2: Take rock samples from the sandstone fracture aquifer 1 in the top plate and transport them to the laboratory for indoor segmented pulse fracturing simulation experiments. Study the relationship between pulse pressure peak value, pulse frequency, segment length, segment interval length, fracturing time and fracture development to determine the optimal pulse frequency, pulse pressure peak value, segment length, segment interval length and fracturing time for segmented pulse fracturing in the drainage operation area, and provide a basis for constructing artificial water diversion channels by pulse fracturing in drainage boreholes.

[0128] Step 3: Based on the fracture development patterns and water-bearing zone distribution obtained from indoor segmented pulse fracturing simulation experiments, design a drainage borehole layout scheme and a segmented pulse fracturing scheme. Specifically, the borehole layout scheme adopts a combination of through-layer straight boreholes and directional long boreholes for segmented pulse fracturing.

[0129] Step 4: After the drilling layout plan is determined, directional drilling is carried out. After the drilling is completed, the site is surveyed to determine the placement of the pulse fracturing pump 4 and the water tank 6.

[0130] Step 5: Install a water-stop sleeve 18 and a matching orifice ball-shaped water-stop valve 17 at the completed borehole opening to prevent excessive water flow from the opening after fracturing connects multiple water-bearing areas. Connect an external flow meter 27 to the orifice valve to monitor the return water volume. Determine whether the artificial water channel formed by pulse fracturing connects to the roof fissure water by comparing the pulse pump injection volume and the rock strata filtration loss with the orifice return water volume. Estimate the water accumulation in the low-lying areas of the roof connected by the artificial water channel.

[0131] Step 6: Before fracturing operations, drainage ditches 28 are installed in the roadways near the fracturing borehole, namely the return airway 3 and the transport roadway 32, to prevent water accumulation in the roadways caused by excessive water discharge from the borehole during fracturing, which could scour the working face. After the pulse fracturing pump 4 and water tank 6 are transported to the operation position, the quantity and integrity of the equipment are checked, and the equipment is connected. The water tank 6 is connected to the water supply pipeline 8 through the water tank supply hose 7 to supply liquid to the water tank; the pulse fracturing pump 4 is connected to the water tank 6 through the pulse pump return hose and the water supply hose 5 to supply liquid to the pulse fracturing pump 4; the pulse fracturing pump 4 is connected to the high-pressure hose 9 to output pulse fracturing water for injection into the borehole; the high-pressure hose 9 is connected to a first tee joint 10 and a pressure relief valve 11 to relieve the water pressure in the pipeline; the pressure sensor 12 and the flow sensor 14 are connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; the pressure sensor 12 is connected to the high-pressure hose 9 through the first tee joint 10 to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing. The pressure sensor signal transmission line 13 is connected to the fracturing control instrument 16, and the flow sensor 14 is connected to the fracturing control instrument 16 through the flow sensor signal line 15. It is used to transmit the pulse pressure and flow signals in the pipeline to the fracturing control instrument, display the pulse pressure and flow curves in real time, and store the data. The orifice ball stop valve 17 and the return water flow meter 27 are connected through the orifice drainage hose 25. The return water flow meter 27 is fixed to the roadway side with steel strap buckle 26. The return water flow meter 27 is connected to the orifice drainage hose 25, and the orifice drainage hose 25 is connected to the drainage ditch 28 of the two roadways.

[0132] Step 7: After the connection and inspection of the pulse fracturing pump 4, pulse pump water supply hose 5, water tank 6, and water tank water supply hose 7 are completed, the drill rig is used to sequentially send the shut-off valve 23, near-bottom packer 22, one-way valve 21, near-orifice packer 20, and high-pressure sealing drill 19 to the designed first-stage fracturing position to start the segmented pulse fracturing operation. Among them, the long borehole is fracturing 3 stages and the short borehole is fracturing 2 stages. The fracturing time for a single stage is 40 min to 50 min. After the first stage of pulse fracturing is completed, the drill rig is used to withdraw part of the high-pressure sealing drill rod. The total length of the withdrawn high-pressure sealing drill rod should be equal to the segment interval length. Then, the next stage of pulse fracturing is carried out. The segmented pulse fracturing of a single hole repeats the above operation until all the designed fracturing stages in a single hole are completed.

[0133] Step 8: After the pulse fracturing operation is completed, the high-pressure sealing drill pipe 19, near-hole packer 20, one-way valve 21, near-hole bottom packer 22, and shut-off valve 23 are sequentially pulled out and their integrity is checked. Then, the above pulse fracturing process is repeated to complete the segmented pulse fracturing of all boreholes.

[0134] Step 9: After completing the pulse fracturing operation, monitor and statistically analyze the return water volume from the drainage borehole to evaluate the effect of pulse fracturing on improving the drainage of water from the top sandstone fracture aquifer. Specifically, monitor the changes in the return water flow meter 27 at the borehole opening. One monitoring cycle is 7 days. Compare the return water volume recorded by the return water flow meter 27 after fracturing with the injection water volume recorded by the pulse fracturing control instrument 16 to estimate the water content of the top sandstone fracture aquifer discharged through artificial water diversion constructed by pulse fracturing within one cycle.

[0135] If the water output from the drainage borehole is too high, the ball stop valve 17 at the borehole opening should be adjusted in time to control the water output from the drainage borehole and achieve fully controllable drainage.

[0136] In this invention, ensuring adequate drainage of the mine is fundamental to successful mining and operational safety. Before mining the working face, a certain number of exploratory boreholes are typically installed to effectively control roof water hazards and ensure safe mining. These boreholes serve both as advanced exploration points and drainage points. To fully drain the water-rich areas of the roof, a drainage borehole layout plan needs to be designed based on the hydrogeological characteristics of the mining area, including the water-bearing areas, water-rich areas, and their continuity. Drainage boreholes are generally classified into two types: through-layer straight boreholes and directional long boreholes.

[0137] For complex geological conditions characterized by high water-bearing capacity of sandstone fissures in the roof, discontinuous aquifers, and poor permeability of dense, intact sandstone masses, drilling boreholes to fully drain water from all discontinuous aquifers would be not only a massive undertaking but also difficult to guarantee complete drainage of the sandstone fissure water. The core solution lies in arranging drainage boreholes and employing technical means to pre-create artificial water-conducting channels within the sandstone fissure aquifers through these boreholes. This improves the permeability of the dense, intact sandstone mass. The artificial water-conducting channels formed by these boreholes connect discontinuous aquifers and water-rich areas, guiding the sandstone fissure water from the roof to the drainage boreholes, thus achieving effective drainage and expanding the drainage area of ​​each borehole.

[0138] The number of boreholes typically used for drilling is relatively small, making it difficult to drain the large and discontinuous amount of fracture water in the roof sandstone. Therefore, to effectively drain the fracture water in the roof sandstone, it is necessary to design and drill additional drainage boreholes. By arranging and fracturing long and short holes in an inclined manner, not only can all water-bearing areas within the radius of the fracture be connected through a single hole, effectively increasing the drainage area of ​​the roof, but also, by arranging the drainage boreholes in an inclined manner, it can be ensured that during the mining process, the roof fracture water that has not been fully drained will flow along the mining-induced fractures to the drainage boreholes, thus achieving advance water release from the working face.

[0139] Hydraulic fracturing refers to the injection of high-pressure fluid (water, gas, etc.) into a borehole, causing the borehole wall to fracture and propagate under fluid-structure interaction. Pre-fracturing the roof of the rock through drainage boreholes creates fractures in the sandstone aquifer, constructing artificial water channels, and is an effective technique for efficiently draining water from sandstone fissures. Conventional hydraulic fracturing pumps have a constant injection rate, and the propagation direction of hydraulic fractures is controlled by the three-dimensional geostress field, extending perpendicular to the direction of the minimum principal stress, resulting in a small number of hydraulic fractures. Pulse pump fracturing utilizes a high-pressure pulse pump to output high-frequency pulsed water, impacting the borehole wall and causing fatigue damage to the rock. This overcomes the influence of the geostress field on the initiation and propagation direction of hydraulic fractures, forming a dense network of fractures within the rock.

[0140] Therefore, the method of constructing artificial water channels through pulse fracturing of drainage boreholes in the roof aquifer not only avoids the need for excessive drainage boreholes and significantly improves the drainage efficiency of exploration and drainage boreholes, but also plays a role in pre-drainage during mining. This method can effectively control mine water hazards and ensure safe mine production even under unfavorable geological conditions.

[0141] In the above embodiments, the hydrophobic boreholes include water exploration and drainage boreholes for geophysical exploration and drainage, and hydrophobic boreholes for pulse fracturing to construct water guiding channels and advance water drainage. The hydrophobic boreholes are divided into cross-layer straight boreholes and directional cross-layer long boreholes.

[0142] The drilling layout scheme includes drilling layout parameters and drilling layout form.

[0143] The borehole layout parameters include borehole length, inclination angle, spacing, azimuth angle, and diameter. The borehole direction should be towards the geometric center of the geometric figure formed by connecting the center points of multiple discontinuous water-bearing areas within the pulse fracturing fracture development radiation zone. Once the borehole opening position is determined, the borehole length can be determined by the distance between the opening position and the geometric center of the geometric figure formed by connecting the center points of the multiple discontinuous water-bearing areas. The borehole inclination angle is the angle between the geometric center of the geometric figure formed by connecting the opening position and the center points of the multiple discontinuous water-bearing areas and the horizontal line.

[0144] The borehole spacing is mainly based on the distribution and continuity of the water-bearing area. If the water-bearing area is evenly distributed and has good continuity, the borehole spacing is usually 30-50m. If the water-bearing area is unevenly distributed and has poor continuity, the boreholes should be arranged so that the water-bearing areas within the fracture development radiation area can be fully connected after pulse fracturing of a single borehole. The spacing between adjacent boreholes should ensure that all discontinuous water-bearing areas between two adjacent boreholes are within the fracture development radiation range, and ensure that each water-bearing area can be fully released. The specific spacing should be determined according to the actual situation.

[0145] To improve the utilization rate of a single borehole and enable it to perform multiple functions, the borehole azimuth angle is generally offset by 30° to 60° towards the working face cut, so that the borehole can provide advanced drainage during the working face mining process.

[0146] The diameter of the drill hole is usually 94mm to 120mm, but the corresponding size of the drill hole can also be customized according to the construction requirements.

[0147] The borehole arrangement includes a through-layer straight borehole arrangement, a directional long borehole arrangement, and a combination of through-layer straight boreholes and directional long boreholes.

[0148] The aforementioned through-layer straight hole arrangement refers to the arrangement of through-layer straight holes in the working face roadway for constructing artificial water guiding channels through segmented pulse fracturing. There are two types of through-layer straight holes: fan-shaped arrangement and parallel arrangement.

[0149] Fan-shaped borehole layout refers to arranging multiple boreholes in a drilling site, with the boreholes distributed in a fan shape. The fan-shaped borehole layout method has the advantages of fewer drilling rig movements and higher drilling efficiency, and is suitable for draining water in localized discontinuous aquifers with relatively concentrated distribution.

[0150] Parallel borehole layout refers to arranging multiple sets of alternating long and short boreholes in the inclined working faces of the two roadways of a coal mining face. In the borehole layout plan, the planar projections of the alternating long and short boreholes are parallel to each other. The advantages of parallel boreholes are reduced construction volume and shorter operation time, and they can also play a role in pre-drainage and water diversion during face mining. The alternating arrangement of long and short boreholes is used to reduce the blind zone in aquifer pulse fracturing.

[0151] The aforementioned directional long borehole arrangement refers to the deployment of long directional boreholes into the sandstone aquifer in the coal seam roof using a directional drilling rig in the working face roadway. The borehole length is generally greater than 200m, and the borehole orientation is parallel to the working face advance direction. Because the majority of the directional long borehole trajectory lies within the roof sandstone aquifer, segmented pulse fracturing within these boreholes allows for extensive aquifer modification and the formation of numerous artificial water-conducting fractures. Therefore, the drainage coverage of a single borehole is substantial. Furthermore, the parallel orientation of the borehole to the working face advance direction also facilitates pre-drainage during working face mining.

[0152] The combined arrangement of through-layer straight holes and directional long boreholes refers to the arrangement of two types of boreholes in the working roadway: through-layer straight holes and directional long boreholes. First, directional long boreholes are used to create large-scale artificial water-conducting fractures through segmented pulse fracturing to drain water from the roof fracture aquifers. Then, for aquifer areas not radiated by the directional long boreholes or for aquifers with strong localization, through-layer straight holes are used for local water drainage as a supplementary guarantee, reducing blind spots of artificial water-conducting fractures and more fully connecting discontinuous aquifer areas in the roof.

[0153] The single-segment fracturing length and segment interval length are determined based on the indoor segmented pulse fracturing simulation experiment after on-site sampling, rock lithology, rock mechanical parameters, pulse peak value and frequency.

[0154] The single-stage fracturing time is generally around 20-60 minutes. It should be combined with the geological characteristics of the mining area to ensure that the constructed artificial water diversion channel can effectively improve the permeability of the rock strata, connect the water-bearing areas, and achieve the purpose of effective water drainage.

[0155] The arrangement of drainage boreholes can also serve as monitoring boreholes. This means that during the fracturing process, the extent of the artificial water channel expansion during pulse fracturing can be evaluated by observing the water outflow from the boreholes of adjacent boreholes before and after fracturing, and it can be determined whether the constructed artificial water channel has connected adjacent boreholes.

[0156] The water-bearing area also includes undiscovered old goaf water above the coal seam roof. directional long boreholes or cross-layer boreholes are drilled in the roadway, with water-stop sleeves and valves installed at the borehole openings. Pulse fracturing is performed on the drainage boreholes that have not yet produced water to construct artificial water channels to connect the old goaf area and fully drain the accumulated water. The drainage situation is monitored closely during fracturing. If a large amount of water emerges from the borehole after fracturing, the water-stop valve should be adjusted promptly to control the water output from the drainage boreholes, achieving fully controllable drainage and ensuring operational safety.

[0157] The monitoring and evaluation of the operational effectiveness includes two aspects: monitoring and evaluation of the effect of pulse fracturing in the top plate fractured aquifer and monitoring of the effect of drainage.

[0158] Monitoring the effect of pulse fracturing in fractured aquifers includes monitoring the number and distribution of pulse fracturing cracks on the borehole walls of drainage boreholes, and monitoring the extent of pulse fracturing crack propagation.

[0159] The number and distribution morphology of pulse fracturing fractures in the borehole wall of the water-draining borehole were monitored using a borehole inspection instrument. After drilling was completed, the borehole wall morphology of the fracturing section was observed using a borehole inspection instrument before pulse fracturing. After pulse fracturing, another observation of the fracturing section was conducted, and the number and distribution morphology of pulse fracturing fractures in the water-draining borehole were compared and analyzed.

[0160] Monitoring the propagation range of pulse fracturing fractures in drainage boreholes involves using adjacent boreholes as observation points. If water is observed or the water flow rate increases in adjacent boreholes during the pulse fracturing process, it indicates that the pulse fracturing fractures have propagated to the adjacent boreholes.

[0161] The monitoring of water drainage effect mainly includes two aspects: statistics on the amount of water returned from the borehole after pulse fracturing and statistics on the water infiltration of the roadway roof during normal mining.

[0162] The statistics on borehole return water volume after pulse fracturing refer to monitoring the pump flow rate during fracturing using a flow sensor, calculating the rock stratum filtration loss based on indoor fracturing simulation experiments conducted in the laboratory, monitoring the borehole return water volume after pulse fracturing using a borehole return water flow meter, and determining whether the artificial water channel formed by pulse fracturing connects the roof fracture water by the difference between the pulse pump water volume, the rock stratum filtration loss, and the borehole return water volume, and estimating the water volume in the roof aquifer area connected by the artificial water channel.

[0163] The statistics on water seepage from the roof of the roadway during normal mining operations refer to the observation and recording of water seepage from the roof before and after fracturing, as well as the water seepage from the roof during mining operations. The macroscopic phenomena are used to visually evaluate the effect of pulse fracturing on promoting the drainage of water in the water-bearing areas of the sandstone fractures in the roof.

[0164] Pulse fracturing of the roof fracture aquifer drainage borehole has the dual function of drainage and mine pressure control. It can not only promote the drainage effect of the water-bearing area of ​​the roof sandstone fracture, but also pre-fracture the coal seam roof, reduce the collapse step of the roof during the mining process, and reduce the mine pressure manifestation during the mining period.

[0165] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0166] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0167] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0168] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

Claims

1. A method for constructing artificial water-conducting channels by pulse fracturing through drilling holes in the top aquifer, characterized in that, Includes the following steps: S100. Collect hydrogeological information of the mining area and explore the specific stratigraphic position and water volume of the sandstone fissure aquifer in the roof. S200. Take rock samples from the sandstone fracture aquifer in the top plate and conduct segmented pulse fracturing simulation experiments. By analyzing the relationship between pulse pressure peak value, pulse frequency, segment length, segment interval length, fracturing time and fracture development, determine the optimal pulse frequency, pulse pressure peak value, segment length, segment interval length and fracturing time for segmented pulse fracturing in the drainage operation area. S300. Based on the fracture development pattern in the segmented pulse fracturing simulation experiment and the specific strata and water volume of the sandstone fracture aquifer in the top plate, determine the drainage borehole layout parameters, drainage borehole layout form and segmented pulse fracturing parameters. S400. Drilling is carried out according to the drainage borehole layout parameters and drainage borehole layout form. After the drilling is completed, the site is explored to determine the placement position of the pulse fracturing equipment. S500. After the construction is completed, install a water-stopping sleeve and a matching orifice valve at the opening of the drainage borehole. Connect the orifice valve to an external flow meter to monitor the return water volume at the orifice. Determine whether the artificial water channel formed by pulse fracturing connects the top plate fissure water by the difference between the pulse pump injection volume and the rock stratum filtration loss volume and the orifice return water volume. Estimate the water volume of the top plate water-bearing area connected by the artificial water channel. Before fracturing operations, artificial water diversion channels are set up in the roadway near the opening of the water drainage borehole. Once the pulse fracturing equipment is transported to the work location, check the quantity and integrity of the equipment, and then connect the equipment. After the S700 pulse fracturing equipment connection inspection is completed, the drilling rig sequentially sends the shut-off valve, near-bottom packer, check valve, near-orifice packer, and high-pressure sealing drill to the designed first-stage fracturing position to begin the segmented pulse fracturing operation. After the first-stage pulse fracturing is completed, the drilling rig withdraws part of the high-pressure sealing drill rod. The total length of the withdrawn high-pressure sealing drill rod should be equal to the segment interval length. Then, the next stage of pulse fracturing is carried out. The segmented pulse fracturing of a single hole repeats the above operation until all designed fracturing stages within a single hole are completed. After the S800 pulse fracturing operation is completed, shut down the pulse fracturing pump, open the pressure relief valve in the pipeline to release the residual fracturing fluid in the pipeline, and wait for the pressure in the pipeline to drop to 0. Then, sequentially push out the high-pressure sealing drill pipe, near-hole packer, check valve, near-hole bottom packer, shut-off valve and other equipment and check their integrity. Repeat the above pulse fracturing process to complete the segmented pulse fracturing of all boreholes in sequence. S900 After completing the pulse fracturing operation, monitor and count the return water volume of the drainage borehole, evaluate the effect of pulse fracturing on improving the drainage of water in the sandstone fracture aquifer in the top plate, and if the water output of the drainage borehole is too large, adjust the ball stop valve at the borehole opening in time to control the water output of the drainage borehole.

2. The method for constructing artificial water-conducting channels by pulse fracturing drilling in the top aquifer according to claim 1, characterized in that, In step S100: The hydrogeological information of the mining area was collected through hydrogeological surveys, three-dimensional seismic exploration, and spatial analysis using geographic information systems. The specific location and water volume of the aquifer in the fractured sandstone of the top plate were determined through advance exploration by setting up several exploratory boreholes in the mining area.

3. The method for constructing artificial water-conducting channels by pulse fracturing drilling in the top aquifer according to claim 1, characterized in that, In step S300: The parameters for the layout of drainage boreholes include borehole length, inclination angle, spacing, azimuth angle, and diameter; The endpoint of the drainage borehole layout is located at the geometric center of the geometric figure formed by connecting the center points of multiple discontinuous water-bearing areas that can be included in the radiation area of ​​the pulse fracturing fracture development.

4. The method for constructing artificial water-conducting channels by pulse fracturing drilling in the top aquifer according to claim 3, characterized in that, In step S300: The spacing of the drainage boreholes is designed based on the distribution and continuity of the water-bearing area; If the water-bearing area is evenly distributed and has good continuity, the spacing between drainage boreholes should be 30–50 m. If the water-bearing area is unevenly distributed and has poor continuity, the drainage boreholes should be arranged so that the water-bearing areas within the fracture development radiation area can be fully connected after pulse fracturing of a single borehole. The spacing between adjacent drainage boreholes should ensure that all discontinuous water-bearing areas between two adjacent boreholes are within the fracture development radiation range.

5. The method for constructing artificial water-conducting channels by pulse fracturing drilling in the top aquifer according to claim 4, characterized in that, In step S300: The azimuth angle of the drainage borehole is offset by 30° to 60° towards the working face cut, so that the drainage borehole can drain water in advance during the working face mining process; the diameter of the drainage borehole is 94mm to 120mm; the single-stage fracturing time is 20 to 60min.

6. The method for constructing artificial water-conducting channels by pulse fracturing drilling in the top aquifer according to claim 1, characterized in that, In step S300: The arrangement of the drainage boreholes includes a through-layer straight borehole arrangement, a directional long borehole arrangement, and a combination of through-layer straight boreholes and directional long boreholes.

7. The method for constructing artificial water-conducting channels by pulse fracturing drilling in the top aquifer according to claim 6, characterized in that, In step S300: The perforated arrangement includes fan-shaped perforations, parallel perforations, and a combination of fan-shaped and parallel perforations.

8. The method for constructing artificial water-conducting channels by pulse fracturing drilling in the top aquifer according to claim 7, characterized in that, In step S300: The aforementioned fan-shaped borehole layout refers to the arrangement of multiple boreholes in a drilling site, with the boreholes distributed in a fan shape. Parallel borehole arrangement refers to arranging multiple sets of alternating long and short boreholes in the inclined working face of the two roadways of the coal mining face. The long and short boreholes are parallel to each other in planar projection.

9. The method for constructing artificial water-conducting channels by pulse fracturing in the top aquifer drainage borehole according to claim 6, characterized in that, In step S300: Directional long borehole layout refers to the use of directional drilling rigs to lay directional long boreholes into the sandstone aquifer on the roof of the coal seam in the working face roadway. The borehole length is greater than 200m, and the borehole direction is parallel to the working face advance direction.

10. The method for constructing artificial water-conducting channels by pulse fracturing in the top aquifer drainage borehole according to claim 6, characterized in that, In step S300: The combined arrangement of cross-layer straight holes and directional long holes refers to the arrangement of two types of boreholes in the working roadway: cross-layer straight holes and directional long holes. First, directional long holes are used to create large-scale artificial water-conducting fractures through segmented pulse fracturing to drain water from the roof fracture aquifer. Then, cross-layer straight holes are used for localized water drainage in aquifer areas not radiated by directional long holes or in aquifer areas with strong localization.

11. The method for constructing artificial water-conducting channels by pulse fracturing in a top plate aquifer drainage borehole according to claim 1, characterized in that, In step S600: The connection equipment specifically includes: a water tank connected to the water supply pipeline via a water tank supply hose to supply liquid to the water tank; a pulse fracturing pump connected to the water tank via a pulse pump return hose and a supply hose to supply liquid to the pulse fracturing pump; a pulse fracturing pump connected to a high-pressure hose to output pulse fracturing water and inject it into the borehole; a tee joint and a pressure relief valve connected between the high-pressure hoses to relieve water pressure in the pipeline; a pressure sensor and a flow sensor connected to the high-pressure hose to monitor the pulse pressure and flow rate in the pipeline during pulse fracturing; a pressure sensor connected to the fracturing control instrument via a pressure sensor signal transmission line, and a flow sensor connected to the fracturing control instrument via a flow sensor signal line, to transmit the monitored pulse pressure and flow rate signals in the pipeline to the fracturing control instrument, display the pulse pressure and flow rate curves in real time, and store the data.

12. The method for constructing artificial water-conducting channels by pulse fracturing drilling in a top aquifer according to claim 11, characterized in that, In step S600: The connection between the orifice ball stop valve and the return flow meter is achieved by using steel strap buckles to fix the return flow meter to the roadway side. The return flow meter is connected to the orifice drainage hose, which is then connected to the drainage ditch in the two roadways.

13. The method for constructing artificial water-conducting channels by pulse fracturing drilling in the top aquifer according to claim 1, characterized in that, In step S900: Monitoring and evaluation of operational effectiveness includes monitoring and evaluating the effectiveness of pulse fracturing in fractured aquifers in the roof and monitoring the effectiveness of drainage. Monitoring of the effectiveness of pulse fracturing in fractured aquifers in the top plate includes monitoring the number and distribution of pulse fracturing fractures on the borehole wall of the drainage borehole, and monitoring the propagation range of pulse fracturing fractures. The monitoring of water drainage effect mainly includes the statistics of borehole water return after pulse fracturing and the statistics of water saturation on the roadway roof during normal mining.

14. The method for constructing artificial water-conducting channels by pulse fracturing in a top plate aquifer drainage borehole according to claim 13, characterized in that, In step S900: The monitoring of the propagation range of pulse fracturing fractures in drainage boreholes is carried out by using adjacent boreholes as observation holes. If water is seen or the water flow increases in adjacent boreholes during the pulse fracturing process, it indicates that the pulse fracturing fractures have propagated to the adjacent boreholes. The number and distribution pattern of pulse fracturing fractures in the borehole wall of the water drainage borehole were monitored by a borehole inspection instrument. After the drilling was completed, the borehole wall morphology of the fracturing section was observed with a borehole inspection instrument before pulse fracturing. After pulse fracturing, the borehole wall of the fracturing section was observed again. The number and distribution pattern of pulse fracturing fractures in the water drainage borehole were compared and analyzed.

15. The method for constructing artificial water-conducting channels by pulse fracturing in a top plate aquifer drainage borehole according to claim 13, characterized in that, In step S900: The statistics on borehole return water volume after pulse fracturing refer to monitoring the pump flow rate during fracturing using a flow sensor, calculating the rock stratum filtration loss based on indoor fracturing simulation experiments conducted in the laboratory, monitoring the borehole return water volume after pulse fracturing using a borehole return water flow meter, and determining whether the artificial water channel formed by pulse fracturing connects the roof fracture water by the difference between the pulse pump water volume, the rock stratum filtration loss, and the borehole return water volume, and estimating the water volume in the roof water-bearing area connected by the artificial water channel. The statistics on water seepage from the roof of the roadway during normal mining operations refer to the observation and recording of water seepage from the roof before and after fracturing, as well as the water seepage from the roof during mining operations. The macroscopic phenomena are used to visually evaluate the effect of pulse fracturing on promoting the drainage of water in the water-bearing areas of the sandstone fractures in the roof.

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