A device and method for directional fracturing of rock

Abstract

The present application relates to a device and a method for rock directional fracturing, and relates to the technical field of rock mechanics. The device comprises a primary multifunctional drill rod, a secondary multifunctional drill rod, a jet device, and a detachable drill bit. One end of the multifunctional drill rod is provided with a water injection port, and the other end is provided with a thread connected with the jet device. The multifunctional drill rod is axially provided with a first water guide pipe and a second water guide pipe. An expansion hose is sleeved on the outer wall of the multifunctional drill rod. The directional fracturing using the device comprises the following steps: the jet device is carried by the drill rod to perform pulse-type slotting on the rock wall, the variable-diameter flange is connected with the drilling machine and the multifunctional drill rod, the expansion hose is tensioned after water injection, a fracture network is formed under the guidance of the water jetting slotting, a pressure relief valve is connected after fracturing, and the multifunctional drill rod is taken out. The use of the device for construction realizes the integrated operation of drilling-slotting-guided fracturing-expansion fracturing, can also reduce the use of fracturing fluid, shorten the fracturing time, and realize the directional expansion of the fracture network.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics, and in particular to an apparatus and method for directional rock fracturing. Background Technology

[0002] Hydraulic fracturing technology, as an effective method of pressure relief, is widely used in the field of mining technology. However, the fracturing process requires a large amount of fracturing fluid, and leaked fracturing fluid, once it flows into the working face, can also have a certain impact on underground production activities. While chemical expansion agent fracturing can solve the aforementioned problems, the long reaction time of the chemical agents necessitates manual mixing, making the operation relatively complex and prone to problems such as nozzle formation. Blasting fracturing can achieve ideal fracturing effects, but the use of explosives underground poses certain safety hazards and is subject to restrictions on explosives management. Expansion fracturing technology, similar to chemical expansion agent fracturing, uses volume expansion to fracture the rock mass. As a variant of hydraulic fracturing, it optimizes the problem of maintaining pressure after rock mass fracturing in hydraulic fracturing and is more environmentally friendly and safer than blasting fracturing. However, due to the uncertainty of the fracture propagation direction, its field application still has certain limitations. Summary of the Invention

[0003] In order to improve hydraulic fracturing technology, reduce the use of fracturing fluid, shorten fracturing time, and achieve directional fracturing, this invention provides an apparatus and method for directional fracturing of rocks, the specific technical solution of which is as follows.

[0004] A device for directional rock fracturing includes a primary multi-functional drill rod, a secondary multi-functional drill rod, an ejector, and a disassembly drill bit. The primary and secondary multi-functional drill rods are connected to form a multi-functional drill rod section. One end of the multi-functional drill rod section is provided with a water injection port, and the other end is threaded to connect with the ejector. A first water guide pipe and a second water guide pipe are axially arranged at the end of the multi-functional drill rod. An expansion hose is sleeved on the outer wall of the end of the multi-functional drill rod. The disassembly drill bit is fixed on the ejector. The first water guide pipe is connected to the ejection hole, and the second water guide pipe is connected to the expansion hose.

[0005] Preferably, it also includes multiple secondary multi-functional drill rods, which are connected end to end, and the number of secondary multi-functional drill rods is determined according to the drilling depth and the fracture location.

[0006] Preferably, the ejector has a sealing end and a fixed end at both ends, the sealing end is connected to a multi-functional drill rod, the fixed end is connected to a detachable drill bit, and the ejector surface is provided with ejection holes.

[0007] Preferably, the disassembly drill bit is made of diamond micron powder and cemented carbide material, and has internal threads. The threads of the disassembly drill bit are connected to the fixed end of the jet injector. The expansion hose is in the shape of a hollow cylinder, and the wall of the expansion hose includes an inner bladder layer, a pressure-bearing layer and an anti-wear layer.

[0008] Preferably, the tail end of the two-stage multi-functional drill pipe is connected to the fastening end of the reducing flange, and the reducing flange has four arc-shaped connecting pipes evenly distributed around the axis; the arc-shaped connecting pipes are connected to the water injection cavity.

[0009] Preferably, the walls of the expansion hose are fixed at both ends by sealing plugs in the locking device to form a water injection cavity; the locking device is provided with a slide, the sealing plug is embedded in the slide of the locking device, and a stop block is provided at the end of the locking device to limit the sealing plug; the surface of the stop block is provided with an opening.

[0010] Preferably, the system also includes a water tank, a high-pressure pump, an energy storage device, and a drilling rig. The high-pressure pump is connected to the water tank via a pipeline, and the high-pressure pump is also connected to the energy storage device, which is connected to the drilling rig on the drilling rig.

[0011] A method for directional rock fracturing, utilizing the aforementioned apparatus for directional rock fracturing, includes the following steps:

[0012] S1. Drilling holes for construction on the rock face;

[0013] S2. When the drill bit is removed, start the high-pressure pump to perform non-uniform hydraulic cutting every 1.2-1.5m of drilling, and the guide groove is formed within the expansion range of the expansion hose;

[0014] S3. Turn off the high-pressure pump, connect the reducing flange to the secondary multi-functional drill pipe, start the high-pressure pump, and the expansion hose squeezes the rock wall, causing the crack to expand in a directional manner under the action of the guide groove.

[0015] S4. Open the pressure relief valve, and after the pressure is released, remove the disassembled drill bit from the borehole.

[0016] More preferably, the water flow direction during the hydraulic cutting process is: water tank → high-pressure pump → energy storage device → first water guide pipe → jet nozzle → jet hole; the water flow direction during the directional crack propagation process is: water tank → high-pressure pump → energy storage device → water injection pipe → arc-shaped connecting pipe → second water guide pipe → water injection cavity.

[0017] More preferably, the drilled holes include two or more holes, the spacing between the drilled holes is 2-5m, and the slit distance in the direction of the line connecting the center of the drilled holes is greater than the slit distance in the direction perpendicular to the line connecting the center of the drilled holes.

[0018] The present invention provides a device and method for directional rock fracturing, which offers the following advantages: the device's expansion hose effectively locks in water, solving the problems of fracturing fluid loss and inability to maintain pressure after initial fracturing in conventional hydraulic fracturing, as well as resource waste. Furthermore, the device is easy to manufacture; the expansion hose is made of flexible material, allowing for significant deformation and high-pressure transmission. This method eliminates the need for fracturing fluid during directional crack propagation, resulting in less fracturing fluid usage, shorter fracturing time, and better rock-breaking performance. Through pulsed slotting and expansion hose fracturing, directional crack propagation can be achieved, forming a directional, interconnected fracture network between multiple expansion-fracturing boreholes. Additionally, it is simple to operate and convenient to use, requiring no drill retraction or sealing device installation, achieving integrated drilling-slotting-expansion fracturing operations, thus improving efficiency. The multi-functional drill rod is also reusable. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a device used for directional rock fracturing;

[0020] Figure 2 This is a cross-sectional schematic diagram of a multi-functional drill pipe;

[0021] Figure 3 This is a cross-sectional view of the expansion hose structure;

[0022] Figure 4 This is a cross-sectional view of the expansion hose after it has expanded;

[0023] Figure 5 This is a schematic diagram of the jet ejector structure;

[0024] Figure 6 This is a schematic diagram of a reducing flange structure;

[0025] Figure 7 This is a schematic diagram showing the connection between the reducing flange and the multi-functional drill pipe structure;

[0026] Figure 8 This is a schematic diagram showing the range of hydraulic cuts in multiple boreholes;

[0027] Figure 9 This is a schematic diagram of the cut status of adjacent boreholes;

[0028] Figure 10 This is a schematic diagram showing the state of adjacent boreholes after expansion and fracturing.

[0029] In the diagram: 1-First-stage multi-functional drill rod; 2-Second-stage multi-functional drill rod; 3-Ejector; 4-Drill bit disassembly; 5-Ejector hole; 6-Expansion hose; 7-First water guide pipe; 8-Second water guide pipe; 9-Locking device; 10-Fastening end; 11-Fastening end; 12-Groove interface; 13-Opening; 14-Stop block; 15-Water injection cavity; 16-Sealing plug; 17-Slide; 18-Inner bladder layer; 19-Pressure bearing layer; 20-Wear-resistant layer; 21-Sealing end; 22-Fixed end; 23-Reducing flange; 24-Arc-shaped connecting pipe; 25-Fastening end; 26-Water injection pipe; 27-Connecting tail end; 28-Guide groove; 29-Construction borehole; 30-Top plate; 31-Water tank; 32-High-pressure pump; 33-Storage device; 34-Drill rig; 35-Directional propagation crack. Detailed Implementation

[0030] Combination Figures 1 to 10 As shown, a specific embodiment of the device and method for directional rock fracturing provided by the present invention will be described.

[0031] A device for directional rock fracturing specifically includes a primary multi-functional drill rod 1, a secondary multi-functional drill rod 2, an ejector 3, and a disassembly drill bit 4. The primary multi-functional drill rod 1 and multiple secondary multi-functional drill rods 2 are connected to adjust the borehole depth. The ejector 3 is used to achieve non-uniform hydraulic fracturing. The disassembly drill bit 4 is located at the end and can be replaced to adjust the borehole diameter. Compared with conventional hydraulic fracturing, this device uses less fracturing fluid, requires less fracturing time, and has better rock breaking effect. It can effectively lock in water and solve the problems of fracturing fluid loss and inability to maintain pressure and resource waste after initial fracturing in conventional hydraulic fracturing. The ejector mounted on the multi-functional drill rod can achieve hydraulic directional fracturing, and the attached expansion hose 6 can achieve directional fracture propagation. The device is simple to operate and convenient to use, requiring no drill retraction or the addition of a sealing device. It realizes an integrated operation of drilling-fracturing-expansion fracturing, improving efficiency. At the same time, the multi-functional drill rod can be reused.

[0032] The device comprises a multi-functional drill rod segment formed by connecting a primary multi-functional drill rod 1 and a secondary multi-functional drill rod 2. This segment is cylindrical and made of bearing steel. One end of the segment has a water inlet, and the other end is threaded to connect to an ejector 3. A first water guide pipe 7 and a second water guide pipe 8 are axially arranged at the end of the multi-functional drill rod. These two water guide pipes are isolated from each other but interconnected. An expansion hose 6 is fitted onto the outer wall of the multi-functional drill rod end. The drill bit is fixed to the ejector 3 and can rotate with the multi-functional drill rod segment. The first water guide pipe 7 connects to the ejection hole, and the second water guide pipe 8 connects to the expansion hose. Both the first and second water guide pipes 7 and 8 have expansion hoses on their walls. The primary and secondary multi-functional drill rods can be flexibly assembled and disassembled via threaded interfaces. The length of the drill rod is determined based on its torque and material characteristics. The device also includes multiple secondary multi-functional drill rods 2, connected end-to-end. The number of secondary multi-functional drill rods is determined by the drilling depth and fracture location.

[0033] The ejector 3 has a sealing end 21 and a fixed end 22 at both ends. The sealing end 21 is connected to a multi-functional drill rod, and the fixed end 22 is connected to a detachable drill bit. The surface of the ejector 3 is provided with ejection holes, and the diameter of the ejection holes 5 is about 1cm.

[0034] The disassembly drill bit 4 is made of diamond micron powder and cemented carbide material, and has internal threads. The threads of the disassembly drill bit are connected to the fixed end of the ejector. The expansion hose 6 is a hollow cylinder. The wall of the expansion hose 6 includes an inner bladder layer 18, a pressure-bearing layer 19, and an anti-wear layer 20. The expansion hose 6 is approximately 0.7m long and has a total wall thickness of approximately 8mm. The expansion hose wall has three layers, from the inside out: the inner bladder layer 18, the pressure-bearing layer 19, and the anti-wear layer 20. The inner bladder layer 18 is 1mm thick and made of high-pressure resistant rubber material. The pressure-bearing layer is 4mm thick and made of carbon fiber and nylon material. The anti-wear layer is 3mm thick and made of butadiene rubber material. The expansion hose wall is fixed at both ends by the sealing plug in the locking device 9, forming a water injection cavity 15. The locking device 9 has a slide, and the sealing plug 16 is embedded in the slide of the locking device. The free sliding distance is approximately 0.1m. A stop block 14 is provided at the end of the locking device to limit the sealing plug. The surface of the stop 14 is provided with an opening 13, through which the wall of the expansion hose can be led out.

[0035] The tail end of the secondary multi-functional drill pipe 2 is connected to the fastening end of the reducing flange 23. The reducing flange 23 has four arc-shaped connecting pipes 24 evenly distributed around its axis. The arc-shaped connecting pipes 24 are connected to the water injection cavity 15. The front end of the reducing flange 23 is threaded, and the arc-shaped connecting pipes 24 are arranged axially. The rear end of the reducing flange 23 is provided with a connecting tail end 27, which can be connected to the drill rig 34 by threads. The connecting tail end is also provided with a water injection pipe 26 with a large opening.

[0036] The device also includes a water tank 31, a high-pressure pump 32, an energy storage device 33, and a drilling rig 34. The high-pressure pump 32 is connected to the water tank 31 through a pipeline. The high-pressure pump 32 is also connected to the energy storage device 33, which is connected to the drilling rig on the drilling rig 34.

[0037] A method for directional rock fracturing, utilizing the aforementioned apparatus for directional rock fracturing, includes the following steps:

[0038] S1. Drilling holes for construction on the rock face;

[0039] The drilling can include two or more holes. When performing multi-hole drilling operations, the spacing between the holes is 2-5m. The slit distance in the direction of the line connecting the centers of the 29 drilling holes is greater than the slit distance in the direction perpendicular to the line connecting the centers of the holes.

[0040] S2. When the drill bit is disassembled, the high-pressure pump is started to perform non-uniform hydraulic cutting every 1.2-1.5m of drilling. The guide groove is formed within the expansion range of the expansion hose. The water flow direction during hydraulic cutting is: water tank → high-pressure pump → accumulator → first water guide pipe → jet nozzle → jet hole. The water flow direction during directional crack propagation is: water tank → high-pressure pump → accumulator → water injection pipe → arc-shaped connecting pipe → second water guide pipe → water injection cavity.

[0041] Specifically, during hydraulic slit cutting, the concave fastening end needs to be connected to the drilling rig. Under the action of the high-pressure pump, the high-pressure water flow direction is: water tank 31 → high-pressure pump 32 → energy storage device 33 → drilling rig 34 → large-diameter water guide pipe 8 → jetter 3 → jet hole 5. The detachable drill bit 4 is activated every 1.2-1.5m to perform non-uniform hydraulic slit cutting, ensuring that the formed guide groove 28 is within the expansion range of the expansion hose wall 6. High-pressure water is injected into the jetter 3 through the large-diameter water guide pipe 8 to cut the rock wall and form the guide groove 28. When performing non-uniform hydraulic slit cutting in multiple boreholes, the slit distance L1 in the direction connecting the centers of the construction boreholes 29 should be controlled to be greater than the slit distance L2 perpendicular to the direction connecting the centers of the construction boreholes 29. The advancing distance of the detachable drill bit 4 can be reasonably determined according to specific construction requirements.

[0042] After drilling and hydraulic cutting are completed, the concave fastening end 11 needs to be disconnected from the drilling rig 34 and connected to the reducing flange 23 for expansion fracturing. The fastening end 25 of the reducing flange 23 can be connected to the convex fastening end 10 via threads, and the connecting tail end 27 of the reducing flange 23 can be connected to the drilling rig 34 via threads; the reducing flange 23 is used to cut off the large-diameter water guide pipe 8. The specific water flow direction during the expansion fracturing process is: water tank 31 → high-pressure pump 32 → energy storage device 33 → drilling rig 34 → water injection pipe 26 → arc-shaped connecting pipe 24 → small-diameter water guide pipe 7 → water injection cavity 15. The first-stage multi-functional drill rod 1 and the second-stage multi-functional drill rod 2 have a diameter of 85mm and a length of 1.2m, and are connected to the jet injector 3 by a large-diameter water guide pipe 8 along the central axis. The first-stage multi-functional drill rod 1 and the second-stage multi-functional drill rod 2 have eight small-diameter water guide pipes 7 distributed circumferentially along the central axis, which are connected to the water injection cavity 15. The large-diameter water pipe 8 has a diameter of 2cm, and the small-diameter water pipe 7 has a diameter of 1cm.

[0043] S3. Turn off the high-pressure pump, connect the reducing flange to the secondary multi-functional drill pipe, start the high-pressure pump, and the expansion hose squeezes the rock wall, causing the crack to expand in a directional manner under the action of the guide groove.

[0044] Specifically, the high-pressure pump 32 is shut down, and a reducing flange 23 is connected to the interface of the drilling rig 34. The other end of the reducing flange 23 is connected to the second-stage multi-functional drill rod 2. The high-pressure pump 32 is restarted, and water is injected into the water injection cavity 15 through the reducing flange 23. The specific water flow direction is: water tank 31 → high-pressure pump 32 → energy storage device 33 → drilling rig 34 → water injection pipe 26 → arc-shaped connecting pipe 24 → small-diameter water guide pipe 7 → water injection cavity 15. The expansion hose wall 6 continuously expands and compresses the surrounding rock wall, causing damage to the rock wall structure. Under the intervention and guidance of the guide groove 28, directional propagating cracks 35 can be formed in the top plate 30.

[0045] S4. Open the pressure relief valve, and after the pressure is released, remove the disassembled drill bit from the borehole.

[0046] This method completes drilling, slotting, and directional expansion fracturing, simplifying the operation process compared to conventional hydraulic fracturing. It uses expansion hoses to seal and lock in the fracturing fluid, solving the problem of insufficient pressure maintenance for further fracturing due to fluid loss, while also reducing resource waste. The operation is green and safe, allowing for pre-fabricated slots and the formation of a directional fracture network between multiple boreholes.

[0047] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for rock directional fracturing using a device for rock directional fracturing, characterized in that, The device comprises a primary multifunctional drill rod, a secondary multifunctional drill rod, a jet device, and a detachable drill bit, the primary multifunctional drill rod and the secondary multifunctional drill rod are connected to form a multifunctional drill rod section, one end of the multifunctional drill rod section is provided with a water injection port, the other end is provided with a thread connected with the jet device, the axial direction of the multifunctional drill rod end is provided with a first water guide pipe and a second water guide pipe, the outer wall of the multifunctional drill rod end is sleeved with an inflatable hose; the detachable drill bit is fixed on the jet device; the second water guide pipe is connected with a jet hole, and the first water guide pipe is connected with the inflatable hose; the detachable drill bit is made of diamond micro powder and hard alloy material, is internally provided with a thread, and the thread of the detachable drill bit is connected with a fixed end of the jet device; the inflatable hose is in a hollow cylindrical shape, the pipe wall of the inflatable hose comprises an inner capsule layer, a pressure bearing layer and an anti-wear layer; the convex fixed end provided at the tail end of the secondary multifunctional drill rod is connected with the fastening end of the variable diameter flange, the variable diameter flange is uniformly distributed with four arc-shaped communication pipes along the axial direction; the arc-shaped communication pipes are connected with a water injection cavity; the pipe wall of the inflatable hose is fixed at both ends through a sealing sliding plug in a locking device to form a water injection cavity; a sliding channel is arranged in the locking device, the sealing sliding plug is embedded in the sliding channel of the locking device, and a stop block is arranged at the end of the locking device to limit the sealing sliding plug; an opening is arranged on the surface of the stop block. A plurality of secondary multifunctional drill rods are further included, the secondary multifunctional drill rods are connected end to end, the number of the secondary multifunctional drill rods is determined according to the drilling depth and the position of the crack; the jet device is provided with a sealing end and a fixed end at both ends, the sealing end is connected with the primary multifunctional drill rod, the fixed end is connected with the detachable drill bit, and the surface of the jet device is provided with a jet hole; a water tank, a high-pressure pump, an energy accumulator and a drilling rig are further included, the high-pressure pump is connected with the water tank through a pipeline, the high-pressure pump is further connected with the energy accumulator, and the energy accumulator is connected with the drilling rig on the drilling rig; the steps of the method comprise: S1. drilling a hole in a rock wall; S2. starting the high-pressure pump to perform non-uniform hydraulic slotting every time the detachable drill bit drills 1.2-1.5 m, and a guide slot is formed in the inflation range of the inflatable hose; S3. closing the high-pressure pump, connecting the variable diameter flange with the secondary multifunctional drill rod, starting the high-pressure pump, continuously inflating and extruding the pipe wall of the inflatable hose to the surrounding rock wall, and damaging the rock wall structure to form a directional expansion crack in the roof under the intervention and guidance of the guide slot; S4. opening a pressure relief valve, and taking out the detachable drill bit from the hole after pressure relief; The flow direction of the water flow in the process of hydraulic slotting is: water tank→high-pressure pump→energy accumulator→second water guide pipe→jet device→jet hole; the flow direction of the water flow in the process of directional expansion crack is: water tank→high-pressure pump→energy accumulator→water injection pipe→arc-shaped communication pipe→first water guide pipe→water injection cavity; the diameter of the first and second multifunctional drill rods is 85 mm, the length is 1.2 m, and one second water guide pipe is arranged along the central axis and communicated with the jet device; eight first water guide pipes are distributed along the central axis and communicated with the water injection cavity; the diameter of the second water guide pipe is 2 cm; the diameter of the first water guide pipe is 1 cm. The drill holes are more than two, the distance between the drill holes is 2-5m, and the slit distance in the direction of the drill hole center line is greater than the slit distance perpendicular to the direction of the drill hole center line.

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