A device for underground electric pulse fracturing hard rock based on liquid-electric effect

Abstract

The invention discloses an underground electric pulse fracturing hard top device based on liquid-electric effect, comprising a crawler-type walking chassis, a water storage tank, a cab, a power storage box, a water pipe, a water pump, a hydraulic system and a rotating box; the hydraulic system can control the rotating box to a specified angle through a rotation locking device; the rotating box is provided with a power transmission port, a drilling rig, a drill rod, a high-pressure water pump and a water pipe; a device box fixed on the outer side of the rotating box is provided with a current limiting protection resistor, an energy storage capacitor, a grounding device, a gas gap switch, a wire retractable disk and a water pipe; a telescopic tube is provided on the outer side of the device box, an inflatable rubber plug is installed at one end of the telescopic tube away from the device box, and the inside of the telescopic tube is hollow and equipped with a water pipe and an electrode structure; the invention installs a drilling device and an electric pulse fracturing device on one device, realizes the integration of "drilling-cutting-liquid injection-discharging" of underground electric pulse fracturing rock mass, and makes rock mass fracturing more efficient; no sparks are generated during the electric pulse fracturing process, and the construction is safer.

Description

Technical Field

[0001] The invention relates to a device for underground electric pulse fracturing of hard rock mass based on liquid-electric effect, belonging to the field of rock mass fracturing. Background Art

[0002] In the process of coal mining, as the working face continues to advance, hard rock will appear in front of the working face and the length of the remaining roof in the goaf will continue to increase, which will not only hinder the continued advancement of the working face, but also be affected by the impact of the overlying rock strata and distant rock strata. It is easy to induce roof collapse accidents. Therefore, it is necessary to pre-fracture the hard rock in front of the working face and the overlying rock in the goaf, transform the rock structure and weaken the rock strength, form a weak surface that is conducive to rock destruction, and induce the rock to break and crush in time under the action of mine pressure, accelerate the advancement of the working face and the occurrence of roof accidents. Generally, when encountering rock masses that require greater fracturing strength underground, high-pressure hydraulic fracturing or deep hole blasting are usually used to fracture the rock mass.

[0003] However, these traditional fracturing methods all have certain defects. For example, high-pressure hydraulic fracturing uses water pressure to cause cracks to start and expand, which makes it difficult to seal the hole. At the same time, it is easily affected by the original cracks in the rock mass, causing the overall expansion direction of the cracks to deflect, thus failing to achieve the intended fracturing effect; deep hole blasting requires filling with a large amount of high explosives, which is easy to form a strong shock wave inside the borehole, causing a large stress disturbance to the internal rock formation, and there is a safety hazard of inducing dynamic disasters. In addition, the degree of damage to the surrounding rock around the borehole is relatively large, and it is not easy to achieve directional fracturing. Therefore, in view of the problems existing in the prior art, a new type of rock fracturing device and method is urgently needed, which not only has good mobility and safety, but also has a high controllability of the crack expansion direction. Compared with the traditional fracturing method, it is easier to form effective directional cracks and improve the efficiency of construction. Summary of the invention

[0004] The present invention aims to provide an underground electric pulse fracturing device for hard rock based on the hydroelectric effect, which solves the problem that the hard rock hinders the advancement of the working face and the large-scale collapse of the roof.

[0005] Compared with the previous rock fracturing technology, the present invention applies electric pulse fracturing technology to rock fracturing under the mine. On the basis of realizing directional fracturing, it also has better maneuverability, controllability and safety, and greatly improves work efficiency.

[0006] The present invention provides an underground electric pulse fracturing device for hard rock mass based on the liquid-electric effect, comprising a crawler-type walking chassis, a fixed platform is arranged on the crawler-type walking chassis, and a water storage tank, a cab, a power storage box, a water pipe, a water pump, a hydraulic system, and a rotating box are installed on the fixed platform;

[0007] The hydraulic system includes a hydraulic pump A, a hydraulic pump B, a rear-end fixed hinge support, and a front-end fixed hinge support fixed on a fixed platform; the hydraulic system also includes four connecting rods and four hydraulic cylinders, the lower ends of the two A-group connecting rods are connected to the rear-end fixed hinge support with pins, and the top end of the A-group connecting rod is connected to the bottom end of the B-group connecting rod and the top end of the B-group hydraulic cylinder with a pin through a Y-type joint.

[0008] The bottom end of the hydraulic cylinder of group B is connected to the front fixed hinge support by a pin. The hydraulic pump B supplies oil to and discharges oil from the hydraulic cylinder of group B through the oil inlet pipe of group B and the oil outlet pipe of group B. The hydraulic pump A supplies oil to and discharges oil from the hydraulic cylinder of group A in the same way. The two ends of the hydraulic cylinder of group A are respectively connected to the middle of the connecting rod of group A and the middle of the connecting rod of group B through fixed hinge supports. The rotation locking device is fixed to the top of the connecting rod of group B on the outside. After the rotation locking device is powered on, it can rotate to a certain angle and then lock the angle unchanged. There are protrusions on both sides of the rotating box (27) embedded in the rotation locking device. The rotation locking device can drive the rotating box to rotate to a certain angle and then fix it. A charging and discharging control box is built in the cab, and the charging voltage can be selected between 5kV and 10kV. According to the "Safety Regulations for Coal Mines", the high voltage used in coal mines shall not exceed 10kV.

[0009] Furthermore, a power transmission port, a drilling rig, a drill rod, a high-pressure water pump, and a water pipe are installed in the rotating box. The drill rod runs through the rotating box, and the power transmission port is connected to the power storage box through wires, and electricity can be transmitted to the drilling rig and the device box through the wires; a high-pressure water drilling and cutting integrated drill bit is installed on the top of the drill rod, and a water pipe is connected to the bottom. The middle of the drill rod is a hollow structure, and the water pipe is connected to the bottom of the drill rod; the high-pressure water pump is connected to the water storage tank through the water pipe, and can pump water from the water storage tank, and then transport it to the drill rod through the water pipe, and then the water is transported from the hollow area of ​​the drill rod to the high-pressure water drilling and cutting integrated drill bit and the water outlet.

[0010] Furthermore, the device box is fixed on the outside of the rotating box, and a current limiting protection resistor, an energy storage capacitor, a grounding device, a gas gap switch, a wire retractable tray, and a water pipe are installed in the device box. The energy storage capacitor is composed of multiple groups of capacitors connected in parallel, and the capacitance of the energy storage capacitor can be adjusted by adjusting the connection method. The adjustable range of the capacitor is 20μF~60μF; according to the formula: , , it can be calculated that the energy released by the electric pulse during one impact is in the range of 250kJ~3000kJ, where: E is the initial energy stored in the capacitor, E w is the shock wave energy, C is the capacitance of the energy storage capacitor, U is the charging voltage, is the efficiency of converting initial energy into shock wave energy, The value range is 10%-30%.

[0011] A telescopic tube is fixed on the outside of the device box. The telescopic tube is electrically driven and can be freely adjusted in length. The maximum extension length is 10m. An inflatable rubber plug is installed at the end of the telescopic tube away from the device box. The inside of the telescopic tube is hollow and equipped with a water pipe and an electrode. During the extension and contraction of the telescopic tube, the discharge wire is retracted and released through the wire retracting disk to ensure the normal discharge of the electrode. At the same time, a certain length of water pipe is reserved in the device box.

[0012] Furthermore, the electrode structure includes a high-voltage electrode, a fixing nut, a polypropylene insulating sleeve, a fixing ring, a rubber gasket, an electrode shell, an electrode shell hole, and a grounding electrode. The high-voltage electrode passes through the built-in cavity of the polypropylene insulating sleeve, and is fixed to the polypropylene insulating sleeve by the fixing nut through the high-voltage electrode thread; then the polypropylene insulating sleeve is placed in the built-in cavity of the electrode shell; the polypropylene insulating sleeve and the electrode shell are fixed by the fixing ring; the grounding electrode passes through the grounding end of the electrode shell, and is fixed by the fixing nut through the grounding electrode thread.

[0013] The discharge-induced cracking process is to store energy in the energy storage capacitor. When the charging is completed, the switch is triggered, and the high-voltage pulse is loaded onto the load electrode through the transmission wire. The energy is released between the tip of the high-voltage electrode and the tip of the ground electrode to complete the electric pulse discharge. The energy of the electric pulse can be divided into discharge channel energy, impact energy, radiation energy, and bubble pulsation energy. The generated shock wave energy mainly comes from the impact energy and bubble pulsation energy.

[0014] This embodiment provides the above-mentioned method for underground electric pulse fracturing hard rock mass based on the hydroelectric effect, comprising the following steps:

[0015] Step 1: Before using the device, first determine the stress state of the rock mass by measuring the in-situ stress in the well, formulate a clear fracturing plan, and select the drilling layout location;

[0016] Step 2: Use a 45mm diameter high-pressure water drill and cutter to drill the rock at the selected drilling location. Stop drilling after reaching the specified depth, start the high-pressure water pump, input high-pressure water to the drill bit for cutting, and at the same time, move the drill rod backward to form axial cracks on both sides of the borehole. After the cutting reaches the specified length, stop cutting and withdraw the drill rod.

[0017] Step 3: Supply oil to the hydraulic cylinders of group A and group B through hydraulic pump A and hydraulic pump B respectively, so that their hydraulic columns extend and the height of the rotating box decreases. Remove the drill rod and drill bit, and return oil to the hydraulic cylinders of group A and group B to shorten their hydraulic columns and increase the height of the rotating box.

[0018] Step 4: Adjust the electrode to be vertically upward by rotating the locking device, align the electrode with the center of the borehole, transport the electrode to the specified position in the borehole by adjusting the length of the telescopic tube, and inflate the inflatable rubber plug to seal the borehole.

[0019] Step 5: Start the high-pressure water pump and inject water into the sealed borehole. After the water is filled, turn off the high-pressure water pump and close the water outlet.

[0020] Step six: adjust the energy storage capacitor to the specified capacitance size, operate the charge and discharge control box, charge the energy storage capacitor, and after charging to the specified voltage, turn off the power switch and turn on the electric pulse switch to discharge. The principle of the fracturing is that the discharge fracturing process is to store energy in the energy storage capacitor. When the charging is completed, at the moment of triggering the switch, the high-voltage pulse is loaded onto the load electrode through the transmission wire, and the energy is released at the tip of the high-voltage electrode and the tip of the grounding electrode to complete the electric pulse discharge. The energy of the electric pulse can be divided into discharge channel energy, impact energy, radiation energy, and bubble pulsation energy. The generated shock wave energy mainly comes from impact energy and bubble pulsation energy. The destructive effect of the energy is mainly in the inward extension direction of the slot, and only a small amount of energy acts on both sides of the drilled slot, so effective directional fracturing can be achieved.

[0021] Step 7: Repeat step 5 until the desired cracking effect is achieved, withdraw the electrode, and the construction is completed.

[0022] Beneficial effects of the present invention:

[0023] (1) The drilling device and the electric pulse fracturing device are installed on one device, realizing the integration of "drilling-cutting-fluid injection-discharging" in underground electric pulse fracturing of rock mass, making rock fracturing more efficient;

[0024] (2) No sparks are generated during the electric pulse fracturing process, which will not cause gas explosions, making the construction safer;

[0025] (3) The use of electric pulses to fracture rock mass underground provides a new way to fracture rock mass underground;

[0026] (4) It adopts crawler chassis, which is easy to move. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 It is a three-dimensional structural diagram of the hydraulic system of the present invention;

[0029] Figure 3 It is an enlarged view of the rotating box and its attached parts;

[0030] Figure 4 yes Figure 2Internal structure diagram;

[0031] Figure 5 is an enlarged cross-sectional view of the electrode and the device box;

[0032] Figure 6 It is a diagram showing the relationship between the positions of the drill hole and the electrode during construction;

[0033] Figure 7 It is a horizontal cross-section of the drilling slit;

[0034] Figure 8 is a schematic diagram of the electrode structure;

[0035] Fig. 9 yes Figure 8 A cross-sectional view of the central axis of

[0036] Fig.10 Schematic diagrams of the hollow holes of the electrode shell of different sizes; (a) the hollow hole size is 2mm×10mm, (b) the hollow hole size is 5mm×10mm.

[0037] In the figure: 1- crawler walking chassis, 2- fixed platform, 3- water storage tank, 4- cab, 5- battery box, 6- rear end fixed hinge support, 7- A group connecting rod, 8- A group hydraulic cylinder, 9- B group connecting rod, 10- water pipe, 11- B group hydraulic cylinder, 12- Y-type joint, 13- drill pipe, 14- device box, 15- telescopic pipe, 16- inflatable rubber plug, 17- electrode structure, 18- high-pressure water drilling and cutting integrated drill bit, 19- A group oil inlet pipe, 20- B group oil inlet pipe, 21- B group oil outlet pipe, 22- A group oil outlet pipe, 23- front end fixed hinge support, 24- hydraulic pump B, 25- water pump, 26- hydraulic pump A, 27-rotating box, 28-rotation locking device, 29-drilling rig, 30-power transmission port, 31-electric wire, 32-high-pressure water pump, 33-current limiting protection resistor, 34-energy storage capacitor, 35-grounding device, 36-gas gap switch, 37-wire retractable disk, 38-high-voltage electrode thread, 39-fixing nut, 40-polypropylene insulating ring, 41-fixing ring, 42-rubber gasket, 43-electrode shell, 44-high-voltage electrode tip, 45-electrode shell hole, 46-grounding electrode tip, 47-grounding electrode thread, 48-water outlet, 49-water, 50-rock mass, 51-cutting slit, 52-drilling hole. DETAILED DESCRIPTION

[0038] The present invention is further illustrated by the following examples, but is not limited to the following examples. Example

[0039] like Figure 1-4The present invention provides an underground electric pulse fracturing device for hard rock mass based on the liquid-electric effect, comprising a crawler-type walking chassis 1, a fixed platform 2 is arranged on the crawler-type walking chassis 1, and a water storage tank 3, a cab 4, a power storage box 5, a water pipe 10, a water pump 25, a hydraulic system, and a rotating box are installed on the fixed platform 2;

[0040] The hydraulic system includes a hydraulic pump A 24, a hydraulic pump B 26, a rear end fixed hinge support 6, and a front end fixed hinge support 23 fixed on the fixed platform 2; the hydraulic system also includes four connecting rods and four hydraulic cylinders, the lower ends of the two A group connecting rods 7 are connected to the rear end fixed hinge support 6 with pins, and the top end of the A group connecting rod 7 is connected to the bottom end of the B group connecting rod 9 and the top end of the B group hydraulic cylinder 11 with pins through a Y-type joint 12.

[0041] The bottom end of the hydraulic cylinder 11 of group B is connected to the front fixed hinge support 23 by a pin, and the hydraulic pump B 24 supplies oil to and returns oil to the hydraulic cylinder 11 of group B through the oil inlet pipe 20 of group B and the oil outlet pipe 21 of group B. The hydraulic pump A 26 supplies oil to and returns oil to the hydraulic cylinder 8 of group A in the same way. The two ends of the hydraulic cylinder 8 of group A are respectively connected to the middle of the connecting rod 7 of group A and the middle of the connecting rod 9 of group B through fixed hinge supports. The rotation locking device 28 is fixed to the top of the connecting rod 9 of group B on the outside. After the rotation locking device 28 is powered on, it can rotate to a certain angle and then lock the angle unchanged. There are protrusions on both sides of the rotating box 27 embedded in the rotation locking device 28. The rotation locking device 28 can drive the rotating box 27 to rotate to a certain angle and then fix it. The cab 4 is equipped with a charging and discharging control box, and the charging voltage can be selected between 5kV and 10kV. According to the "Safety Regulations for Coal Mines", the high voltage used in coal mines shall not exceed 10kV.

[0042] Furthermore, the rotating box 27 is equipped with a power transmission port 30, a drilling rig 29, a drill rod 13, a drill rod passing through the rotating box, a high-pressure water pump 32, and a water pipe 10. The power transmission port 30 is connected to the power storage box 5 through the wire 31, and electricity can be transmitted to the drilling rig 29 and the device box 14 through the wire 31; a high-pressure water drilling and cutting integrated drill bit 18 is installed on the top of the drill rod 13, and a water pipe 10 is connected to the bottom. The middle of the drill rod 13 is hollow, and the water pipe 10 is connected to the bottom of the drill rod 13; the high-pressure water pump 22 is connected to the water storage tank 3 through the water pipe, and can pump water from the water storage tank 3, and then transport it to the drill rod 13 through the water pipe 10, and then the water is transported to the high-pressure water drilling and cutting integrated drill bit 18 and the water outlet 48 through the hollow area of ​​the drill rod 13.

[0043] Furthermore, the device box 14 is fixed on the outside of the rotating box 27, and the device box 14 is installed with a current limiting protection resistor 33, an energy storage capacitor 34, a grounding device 35, a gas gap switch 36, a wire retracting disk 37, and a water pipe 10. A telescopic tube 15 is fixed on the outside of the device box 14, and the telescopic tube 15 is electrically driven and can be freely adjusted in length, with a maximum extension length of 10m. The energy storage capacitor 34 is formed by connecting multiple groups of capacitors in parallel, and the capacitance of the energy storage capacitor 34 can be adjusted by adjusting the connection mode, and the adjustable range of the capacitance is 20μF~60μF; an inflatable rubber plug 16 is installed at one end of the telescopic tube 15 away from the device box 14, and the inside of the telescopic tube 15 is hollow and installed with a water pipe 10 and an electrode structure 17. During the extension and contraction process of the telescopic tube 15, the discharge wire 31 is retracted by the wire retracting disk 37 to ensure the normal discharge of the electrode structure 17. At the same time, a certain length of the water pipe 10 is reserved in the device box 14.

[0044] Furthermore, if Figures 8-10 As shown, the electrode structure 17 includes a high-voltage electrode, a grounding electrode, a polypropylene insulating sleeve 40, a rubber gasket 42, an electrode shell 43, a fixing nut 39 and a fixing ring 41; a high-voltage electrode thread 38 is provided at the upper end of the high-voltage electrode, and the middle part of the high-voltage electrode is connected and fixed to the polypropylene insulating sleeve 40 through a fixing nut 39, the high-voltage electrode is located inside the polypropylene insulating sleeve 40, the polypropylene insulating sleeve 40 is fixed to the upper part of the electrode shell 43, and the polypropylene insulating sleeve 40 and the electrode shell 43 are fastened together through a fixing ring 41; a rubber gasket is sleeved at the contact between the polypropylene insulating sleeve 40 and the electrode shell 43 to increase the tightness of the contact between the two; the grounding electrode is fixed to the lower end of the electrode shell 43 through the grounding electrode thread 47; the grounding electrode is screwed into the thread at the bottom of the electrode shell 43, and then fixed by the fixing nut 39; the high-voltage electrode and the grounding electrode are relatively arranged in the empty hole 45 of the electrode shell, and the distance between the grounding electrode and the high-voltage electrode is adjustable by rotating the grounding electrode thread 47 at the lower end, and the distance between the two electrodes is set to 1mm-5mm;

[0045] The high-voltage electrode is 74mm long in total and consists of three parts: the upper end, the middle end, and the lower end. The upper end is a cylinder with a diameter of 4mm and a length of 70mm. A 25mm-long M8 thread is machined on the top of the cylinder to form the upper end of the high-voltage electrode thread 38; the middle end is a cylinder with a diameter of 5mm and a length of 2mm, and the lower 1mm length chamfer is 30°; the lower end is a cylinder with a diameter of 2mm and a length of 2mm, and the tip is chamfered at 45° at the bottom; the grounding electrode consists of a smooth cylinder and a threaded cylinder; the smooth cylinder in the upper part is 2mm in diameter and 1mm in length. The tip has a chamfer angle of 3mm and a top angle of 45°; the lower part is an M8 threaded cylinder with a length of 17mm; the polypropylene insulating collar 40 is a cylinder with a diameter of 8mm and a length of 95mm; the diameter of the built-in cavity is 4mm; a polypropylene circular collar with a diameter of 12mm and a length of 4mm is added at a distance of 35mm from the top, and its function is to fix it on the electrode shell 43; the appearance of the electrode shell 43 is cylindrical, and the interior is hollow, and the electrode passes through it. The electrode shell is composed of three sections of cylinders with different outer diameters. The first section of the upper cylinder The electrode shell 43 is connected to the fixed ring 41, and the inside of the second section of the cylinder in the middle is provided with a rubber gasket, and the outside of the third section of the cylinder at the bottom is a smooth structure; the first section of the cylinder of the electrode shell 43 is provided with an external thread for connecting the fixed ring 41; the center of the top of the first section of the cylinder is a step hole, and the hole on the step hole is connected to the polypropylene insulating ring 40; the bottom of the second section of the cylinder is provided with a hole for placing a rubber gasket 42; the center of the bottom of the third section of the cylinder is provided with an internal thread for fixing the grounding electrode, and the cylindrical surface above it is provided with an electrode shell hole 45 to expose the electrode; the inside of the fixed ring 41 A thread is set, and a circular hole with a diameter of 8 mm is drilled on the top of the fixed circular ring, and a polypropylene insulating ring 40 passes through the circular hole; the electrode shell hollow hole 45 is provided with one or more, and the cross-section of the electrode shell hollow hole 45 is rectangular, and the size is 2mm×10mm, 3mm×10mm or 5mm×10mm; a hollow hole is drilled at the bottom of the third section of the cylinder of the electrode shell 43, or two hollow holes are symmetrically arranged front and back, or three hollow holes are evenly distributed along the circumference; by setting the size and position of the hollow hole, the shock wave direction of the electrode structure 17 can be controlled and the energy focusing can be achieved.

[0046] The discharge-induced fracturing process is to store energy in the energy storage capacitor 34. When the charging is completed, at the moment of triggering the switch, the high-voltage pulse is loaded onto the load electrode structure 17 through the transmission wire 31, and the energy is released between the high-voltage electrode tip 44 and the ground electrode tip 46 to complete the electric pulse discharge. The energy of the electric pulse can be divided into discharge channel energy, impact energy, radiation energy, and bubble pulsation energy. The generated shock wave energy mainly comes from the impact energy and the bubble pulsation energy.

[0047] According to the formula: , , it can be calculated that the energy released by the electric pulse during one impact is in the range of 250kJ~3000kJ, where: E is the initial energy stored in the capacitor, E w is the shock wave energy, C is the capacitance of the energy storage capacitor, U is the charging voltage, is the efficiency of converting initial energy into shock wave energy, The value range is 10%-30%.

[0048] This embodiment provides a method for using the above-mentioned device for underground electric pulse fracturing hard rock based on the liquid-electric effect, comprising the following steps:

[0049] Step 1: Before using the device, first determine the stress state of the rock mass by measuring the in-situ stress in the well, formulate a clear fracturing plan, and select the drilling layout location;

[0050] Step 2: Drill the rock mass at the selected drilling position using a high-pressure water drilling and cutting integrated drill bit 18 with a diameter of 45 mm. Stop drilling after the specified depth is reached, and then start the high-pressure water pump 32 to input high-pressure water to the drill bit 18 for cutting. At the same time, the drill rod 13 is retreated to form axial cracks on both sides of the borehole. After the cutting reaches the specified length, stop cutting and withdraw the drill rod 13.

[0051] Step 3: Supply oil to the hydraulic cylinder 8 of group A and the hydraulic cylinder 11 of group B respectively through hydraulic pump A 26 and hydraulic pump B 24, so that their hydraulic columns are extended, the height of the rotating box 27 is lowered, the drill rod 13 and the drill bit 18 are removed, and the oil is returned to the hydraulic cylinder 8 of group A and the hydraulic cylinder 11 of group B, so that their hydraulic columns are shortened, and the height of the rotating box 27 is increased.

[0052] Step 4: Adjust the electrode structure 17 to be vertically upward by rotating the locking device 28, align the electrode structure 17 with the center of the borehole, transport the electrode structure 17 to the specified position in the borehole by adjusting the length of the telescopic tube 15, and inflate the inflatable rubber plug 16 to seal the borehole.

[0053] Step 5: Start the high-pressure water pump 32 to inject water into the sealed borehole. After the water is filled, turn off the high-pressure water pump 32 and close the water outlet 48. Figure 5 shown.

[0054] Step six: adjust the energy storage capacitor 34 to the specified capacitance size, operate the charge and discharge control box, charge the energy storage capacitor 34, after charging to the specified voltage, turn off the power switch, and turn on the electric pulse switch to discharge. The fracturing principle is that the discharge fracturing process is to store energy in the energy storage capacitor 34. When the charging is completed, at the moment of triggering the switch, the high-voltage pulse is loaded onto the electrode structure 17 through the transmission wire 31, and the energy is released at the high-voltage electrode tip 44 and the ground electrode tip 46 to complete the electric pulse discharge. The energy of the electric pulse can be divided into discharge channel energy, impact energy, radiation energy, and bubble pulsation energy. The generated shock wave energy mainly comes from impact energy and bubble pulsation energy. The destructive effect of the energy is mainly in the inward extension direction of the slot, and only a small amount of energy acts on both sides of the drilling slot, so that effective directional fracturing can be achieved.

[0055] Step 7: Repeat step 5 until the predetermined cracking effect is achieved, then withdraw the electrode structure 17 and the construction is completed.

[0056] The above descriptions are merely embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A device for underground electric pulse fracturing of hard rock based on the hydroelectric effect. Features: It includes a crawler-type walking chassis, on which a fixed platform is arranged, and on which a water storage tank, a cab, a power storage box, a water pipe, a water pump, a hydraulic system, and a rotating box are installed; The hydraulic system includes a hydraulic pump A, a hydraulic pump B, a rear fixed hinge support, and a front fixed hinge support fixed on a fixed platform; the hydraulic system also includes four connecting rods and four hydraulic cylinders. The four connecting rods are divided into two A-group connecting rods and two B-group connecting rods; the lower ends of the two A-group connecting rods are connected to the rear fixed hinge support with pins, and the top of the A-group connecting rods is connected to the bottom end of the B-group connecting rods and the top end of the B-group hydraulic cylinders through a Y-type joint with a pin; the bottom end of the B-group hydraulic cylinder is connected to the front fixed hinge support with a pin, and the hydraulic pump B is connected to the front fixed hinge support with a pin through the B The oil inlet pipe of group A and the oil outlet pipe of group B supply and drain oil to the hydraulic cylinder of group B, and the hydraulic pump A supplies and drains oil to the hydraulic cylinder of group A in the same way; the two ends of the hydraulic cylinder of group A are respectively connected to the middle of the connecting rod of group A and the middle of the connecting rod of group B through fixed hinge supports; the outside of the rotation locking device is fixed to the top of the connecting rod of group B, and the rotation locking device can rotate to a specific angle after being powered on, and the locking angle remains unchanged. There are protrusions on both sides of the rotating box embedded in the rotation locking device, and the hydraulic system controls the rotating box to a specified angle through the rotation locking device; The rotating box is equipped with a power transmission port, a drilling rig, a drill rod, a high-pressure water pump, and a water pipe; the drill rod runs through the rotating box, the power transmission port is connected to the power storage box through wires, and electricity is transmitted to the drilling rig and the device box through the wires; a high-pressure water drilling and cutting integrated drill bit is installed on the top of the drill rod, and a water pipe is connected to the bottom. The middle of the drill rod is a hollow structure, and the water pipe is connected to the bottom of the drill rod; the high-pressure water pump is connected to the water storage tank through the water pipe, pumps water from the water storage tank, and then transmits it to the drill rod through the water pipe, and then the water is transmitted to the high-pressure water drilling and cutting integrated drill bit and the water outlet through the hollow area of ​​the drill rod; The device box is fixed on the outside of the rotating box, and a current limiting protection resistor, an energy storage capacitor, a grounding device, a gas gap switch, a wire retractable tray, and a water pipe are installed in the device box; a telescopic tube is fixed on the outside of the device box, and the telescopic tube is electrically driven and can be freely adjusted in length; an inflatable rubber plug is installed at one end of the telescopic tube away from the device box, and the inside of the telescopic tube is hollow and is installed with a water pipe and an electrode structure; The electrode structure includes a high-voltage electrode, a fixing nut, a polypropylene insulating ring, a fixing ring, a rubber gasket, an electrode shell, a hole in the electrode shell, and a grounding electrode; wherein the high-voltage electrode passes through the built-in cavity of the polypropylene insulating ring, and is fixed to the polypropylene insulating ring with a fixing nut through the high-voltage electrode thread; then the polypropylene insulating ring is placed in the built-in cavity of the electrode shell; the polypropylene insulating ring and the electrode shell are fixed with a fixing ring; the grounding electrode passes through the grounding end of the electrode shell, and is fixed with a fixing nut through the grounding electrode thread; by storing energy in the energy storage capacitor, when charging is completed, at the moment the switch is triggered, the high-voltage pulse is loaded onto the load electrode through the transmission wire, and the energy is released between the tip of the high-voltage electrode and the tip of the grounding electrode, completing the electric pulse discharge.

2. The device for underground electric pulse fracturing hard rock mass based on the liquid-electric effect according to claim 1, Features: The maximum extension length of the telescopic tube is 10m. During the extension and contraction process of the telescopic tube, the discharge wire is retracted and released through the wire retracting disk to ensure the normal discharge of the electrode. At the same time, a certain length of water pipe is reserved in the device box.

3. The device for underground electric pulse fracturing hard rock mass based on the liquid-electric effect according to claim 1, Features: There is a charging and discharging control box in the cab, and the charging voltage is 5kV~10kV.

4. The device for underground electric pulse fracturing hard rock mass based on the liquid-electric effect according to claim 1, Features: The energy storage capacitor is composed of multiple groups of capacitors connected in parallel. The capacitance of the energy storage capacitor can be adjusted by adjusting the connection method. The adjustment range of the capacitance is 20μF~60μF; according to the formula: , , It is calculated that the energy released by an electric pulse during a single impact ranges from 250 kJ to 3000 kJ, where: E is the initial energy stored in the capacitor, E w is the shock wave energy, C is the capacitance of the energy storage capacitor, U is the charging voltage, is the efficiency of converting initial energy into shock wave energy, The value range is 10%-30%.

5. The device for underground electric pulse fracturing hard rock mass based on the liquid-electric effect according to claim 1, Features: The upper end of the high-voltage electrode is provided with a thread, and the middle part of the high-voltage electrode is connected and fixed with a polypropylene insulating sleeve ring through a fixing nut. The high-voltage electrode is located inside the polypropylene insulating sleeve ring, and the polypropylene insulating sleeve ring is fixed on the upper part of the electrode shell. The polypropylene insulating sleeve ring and the electrode shell are fastened and connected through a fixing ring; a rubber gasket is sleeved at the contact point between the polypropylene insulating sleeve ring and the electrode shell to increase the tightness of the contact between the two; the grounding electrode is fixed to the lower end of the electrode shell through a thread; the grounding electrode is screwed in through the thread at the bottom of the electrode shell, and then fixed with a nut; the high-voltage electrode and the grounding electrode are relatively installed in the empty hole of the electrode shell, and the distance between the grounding electrode and the high-voltage electrode can be adjusted by rotating the thread at the lower end of the grounding electrode, and the distance between the two electrodes is set to 1mm-5mm; The high-voltage electrode is 74mm long in total and consists of three parts: the upper end, the middle end, and the lower end. The upper end is a cylinder with a diameter of 4mm and a length of 70mm. A 25mm long M8 thread is machined on the top of the cylinder to form the upper end of the high-voltage electrode thread; the middle end is a cylinder with a diameter of 5mm and a length of 2mm, and the lower 1mm length chamfer is 30°; the lower end is a cylinder with a diameter of 2mm and a length of 2mm, and the tip is chamfered at 45° at the bottom; the grounding electrode consists of a smooth cylinder and a threaded cylinder; the diameter of the smooth cylinder in the upper part is The tip is 2mm, 3mm long, and has a 45° chamfer on the top; the lower part is an M8 threaded cylinder with a length of 17mm; the polypropylene insulating ring is a cylinder with a diameter of 8mm and a length of 95mm; the diameter of the built-in cavity is 4mm; at a distance of 35mm from the top, a polypropylene circular ring with a diameter of 12mm and a length of 4mm is added to fix it on the electrode shell; the appearance of the electrode shell is cylindrical, and the inside is hollow, and the electrode passes through it. The electrode shell consists of three sections of cylinders with different outer diameters The first section of the upper cylinder is connected to the fixed ring, the interior of the second section of the middle cylinder is provided with a rubber gasket, and the outer side of the third section of the lower cylinder is a smooth structure; the first section of the cylinder of the electrode shell is provided with an external thread for connecting the fixed ring; the center of the top of the first section of the cylinder is a step hole, and the hole on the step hole is connected to the polypropylene insulating sleeve ring; the bottom of the second section of the cylinder is provided with a hole for placing the rubber gasket; the center of the bottom of the third section of the cylinder is provided with an internal thread for fixing the grounding electrode, and the cylindrical surface above it is provided with an electrode shell hole to expose the electrode; the fixed ring is internally threaded, and a circular hole with a diameter of 8mm is drilled on the top of the fixed ring, and the polypropylene insulating sleeve ring passes through the circular hole; the electrode shell hole is provided with one or more, and the cross-section of the electrode shell hole is rectangular, and the size is 2mm×10mm, 3mm×10mm or 5mm×10mm; a hole is drilled at the bottom of the third section of the cylinder of the electrode shell, or two holes are symmetrically arranged front and back, or three holes are evenly distributed along the circumference; the shock wave direction of the electrode structure can be controlled and the energy focusing can be achieved by setting the size and position of the hole.

6. The device for underground electric pulse fracturing hard rock mass based on the liquid-electric effect according to claim 1, Features: The rotation locking device comprises a locking module and a plurality of engaging members, wherein the engaging members are rotatably coupled to the locking module, and the locking module is engaged with and separated from the engaging members, thereby achieving the stationary state and rotation of the engaging members relative to the locking module; The rotation locking device can keep the rotating box at different tilt angles for various working conditions.

7. A method for fracturing hard rock mass by electric pulses in underground wells based on the hydroelectric effect, using the device according to any one of claims 1 to 6, Features The following steps are involved: Step 1: Before using the device, first determine the stress state of the rock mass by measuring the in-situ stress in the well, formulate a clear fracturing plan, and select the drilling layout location; Step 2: Use a 45mm diameter high-pressure water drill and cutter to drill the rock at the selected drilling location. Stop drilling after reaching the specified depth, start the high-pressure water pump, input high-pressure water to the drill bit for cutting, and at the same time, move the drill rod backward to form axial cracks on both sides of the borehole. After the cutting reaches the specified length, stop cutting and withdraw the drill rod. Step 3: Use hydraulic pump A and hydraulic pump B to deliver oil to hydraulic cylinder group A and hydraulic cylinder group B respectively, so that hydraulic cylinder group A and hydraulic cylinder group B extend, so that the height of the rotating box decreases, remove the drill rod and drill bit, and then drain the oil from hydraulic cylinder group A and hydraulic cylinder group B, so that hydraulic cylinder group A and hydraulic cylinder group B shorten, so that the height of the rotating box increases; Step 4: Adjust the electrode to be vertically upward by rotating the locking device, align the electrode with the center of the borehole, transport the electrode to the specified position in the borehole by adjusting the length of the telescopic tube, and inflate the inflatable rubber plug to seal the borehole; Step 5: Start the high-pressure water pump and inject water into the sealed borehole. After the water is filled, turn off the high-pressure water pump and close the water outlet. Step 6: Adjust the energy storage capacitor to the specified capacitance, operate the charge and discharge control box, charge the energy storage capacitor, after charging to the specified voltage, turn off the power switch, and turn on the electric pulse switch to discharge; Step 7: Repeat step 5 until the desired cracking effect is achieved, withdraw the electrode, and the construction is completed.

8. The method for fracturing hard rock mass by underground electric pulse based on liquid-electric effect according to claim 7, Features: In step six, the discharge fracturing process is to store energy in the energy storage capacitor. When the charging is completed, the switch is triggered at the moment, and the high-voltage pulse is loaded onto the load electrode through the transmission wire, and the energy is released at the tip of the high-voltage electrode and the tip of the ground electrode to complete the electric pulse discharge; the shock wave energy generated mainly comes from the impact energy and the bubble pulsation energy; the destructive effect of the energy is mainly in the inward extension direction of the slot, and only a small amount of energy acts on both sides of the drilled slot, so that effective directional fracturing can be achieved.

Images