A kind of orifice high-temperature high-pressure gas deep hole advanced water pressure conduction explosion shock wave fracturing device and fracturing method

Abstract

The application discloses an orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device, which comprises a pipe body (3), the tail end of the pipe body (3) is connected with an explosion shock wave generating device (6), a blocking ring (4) is movably arranged on the pipe body (3), the blocking ring (4) comprises a water inlet end (41), an expansion part one (42) and a water outlet end (43) which are sequentially and integrally connected, the water inlet end (41) is provided with a water inlet A (44) and a water inlet B (45), and the water outlet end (43) is provided with a water outlet (46). The application further discloses a fracturing method using the orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device. The application can achieve better fracturing effect by using explosion shock wave-water coupling to fracture coal seams, is safer and more environmentally friendly, and can replace roadway construction with long drilling holes, thereby reducing construction amount and being suitable for protective layer pre-fracturing mining.

Description

Technical Field

[0001] This invention belongs to the field of protective layer pre-fracture mining technology, specifically relating to a device and method for fracturing deep holes with high temperature and high pressure gas at the orifice and advanced water pressure conduction of explosive shock waves. Background Technology

[0002] Coalbed methane (CBM) refers to hydrocarbon gases stored in coal seams, primarily composed of methane. These gases are mainly adsorbed onto the surface of coal matrix particles, with some remaining free in the coal pores or dissolved in the coal seam water. It is a associated mineral resource of coal. CBM combustion is very clean, and its calorific value is comparable to natural gas. However, CBM is also a greenhouse gas, with a greenhouse effect approximately 21 times that of carbon dioxide. Therefore, the development and utilization of CBM offers multiple benefits, providing clean energy while reducing greenhouse gas emissions.

[0003] Coalbed methane (gas) is also a major hazard source in coal mines, and coal and gas outbursts cause casualties every year. Gas explosions are even more dangerous, with the most severe casualties and resource losses among all types of accidents. Therefore, mining activities cannot be carried out when gas concentrations are below standard.

[0004] Mining protective layers is a common method in coal mining to eliminate the risk of coal and gas outbursts. The protective layer is the upper or lower coal seam of the main coal seam being mined, and is further divided into upper and lower protective layers based on orientation. After the protective layer is mined, the ground stress in the main coal seam decreases, reducing the risk of coal and gas outbursts. Simultaneously, gas desorption effectively lowers the gas concentration in the main coal seam. However, existing methods for pre-fracking protective layers generally involve blasting, which poses numerous safety hazards and causes pollution, failing to achieve efficient and clean pre-fracking mining of the protective layer. Currently, hydraulic fracturing is also used, but it can only produce a single radial fracture, failing to improve gas extraction rates, and requires the addition of fracturing fluid that severely pollutes groundwater. This invention, however, uses high-temperature, high-pressure gas at the orifice, deep-hole pre-hydrostatic transmission, and explosive shock wave fracturing, which can efficiently pre-fracture the protective layer without causing pollution. Compared to blasting and hydraulic fracturing, it is safer and more environmentally friendly. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a high-temperature, high-pressure gas deep-hole pre-hydraulic pressure conduction explosion shock wave fracturing device. It uses an explosion shock wave generator and high-pressure water coupling to pre-fracture the protective layer, and uses an acoustic damage measurement probe to measure the sound velocity to evaluate the pre-fracturing effect.

[0006] This invention also discloses a fracturing method using a high-temperature, high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device. This method is simple, stable and reliable, and can achieve efficient and clean pre-fracturing mining of the protective layer.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A device for fracturing explosive shock waves in a deep hole with high temperature and high pressure gas through an orifice, comprising a pipe body, the end of which is connected to an explosive shock wave generator. A sealing ring is movably disposed on the pipe body. The sealing ring includes an inlet end, an expansion section, and an outlet end, sequentially and integrally connected. The inlet end has an inlet A and an inlet B; the outlet end has an outlet; inlet B and outlet are connected. Sealing structures are provided on inlet A, inlet B, and outlet. The sealing structure includes threaded grooves on the inlet and outlet ends, with a through hole penetrating the inlet and outlet ends at the center of the groove bottom. A perforated nut is fitted inside the threaded groove, and a perforated sealing gasket is placed at the bottom of the threaded groove. A water pipe passes sequentially through the perforated nut, the perforated sealing gasket, and the through hole. Plugs are movably disposed on the water pipes at inlet A and inlet B.

[0009] The fracturing device of the present invention further includes an acoustic detection device, which includes a hollow rod body with a sealed head, a plurality of acoustic damage measurement probes evenly distributed inside the hollow rod body, a coupling agent filling the hollow rod body, and a water-stop plug sealing the end opening of the hollow rod body.

[0010] The water-stopping plug includes an expansion part two, which is covered with an external elastic layer. The expansion part two and the external elastic layer are bonded together, and a coupling agent inlet is provided on the expansion part two.

[0011] A valve for opening and closing is provided between the pipe body and the explosion shock wave generating device.

[0012] Both the expansion section and the outer surface of the tube body are provided with diagonal lines.

[0013] The outer elastic layer is made of rubber; the second expansion part is made of wear-resistant rubber.

[0014] The bonding area is bonded with polyurethane adhesive.

[0015] The main body of the pipe is a stainless steel pipe; the main body of the hollow rod is a steel rod; and the water pipe is a stainless steel water pipe.

[0016] The coupling agent includes water.

[0017] A fracturing method for a deep-hole fracturing device using high-temperature, high-pressure gas at the orifice and advanced water pressure conduction of an explosive shock wave includes the following steps:

[0018] Step A: Drill a large borehole with a diameter of 140-150 mm and a length of 20-50 m in the middle of the coal seam thickness at the working face using a drilling machine, and drill a small borehole with a diameter of 60-70 mm and a length of 20-50 m at the same horizontal distance of 5-6 m on both sides. All long boreholes are rinsed with clean water to remove coal dust.

[0019] Step B: Install the explosion shock wave generator and the pipe body, insert the pipe body into the bottom of the large borehole, and check whether the valve switch is closed after the pipe body and the explosion shock wave generator are connected. Put the sealing ring on the pipe body, and the distance between the sealing ring and the bottom of the large borehole is 5~6.25m.

[0020] Step C: Fill the expansion section with water through the inlet A on the sealing ring until the pressure reaches at least 2.5 MPa, the length of the sealing ring reaches at least 1.5 m, and the sealing ring and the borehole wall of the large borehole are in full contact to achieve a sealing effect of at least 50 MPa. Then, use a plug to block the inlet A.

[0021] Step D: Fill the large borehole and pipe body with water through the inlet B and outlet on the sealing ring to achieve a high pressure state, with a pressure of at least 20MPa, and then use a plug to block the inlet B.

[0022] Step E: Insert the acoustic detection device containing several acoustic damage probes into the small drill holes on both sides. All acoustic damage probes are evenly distributed in the small drill holes, and the position of the acoustic damage probes is matched with the position of the sealing ring during each pre-cracking. Fill with coupling agent and use a water stop plug to seal the water at the opening of the empty rod body.

[0023] Step F: Use an explosion shock wave generator to generate an explosion shock wave. Open the valve between the pipe body and the explosion shock wave generator. The explosion shock wave couples with the pressurized water in the pipe body. Due to the incompressibility of water, the explosion shock wave is transmitted to the bottom of the large borehole to fracture the coal and rock. Use the acoustic wave damage measurement probe at the corresponding position to observe the acoustic wave velocity until the acoustic wave velocity drops to the longitudinal wave velocity V1. After meeting the pre-fracture requirements, stop the explosion shock wave generator.

[0024] Step G: Unscrew the plug at inlet A. After the sealing ring fails, retract the pipe body by 5~6.25m and refill with water through inlet A to a pressure of at least 2.5MPa. Repeat step DF to reach the next cycle.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. This invention is highly efficient. The shock wave can generate radial and circumferential cracks. The circumferential cracks are distributed within 1m of the outer diameter of the hole. These complex and minute cracks are very conducive to the desorption of gas and form gas production channels. The relatively large radial cracks are the main gas channels connecting the minute cracks. Therefore, this method can greatly improve the gas extraction rate and effectively pre-fracture the protective layer.

[0027] 2. This method uses an intrinsically safe explosive shock wave generator and pressurized water as the medium for transmitting the shock wave. Compared with hydraulic fracturing, it is more environmentally friendly because hydraulic fracturing adds fracturing fluid to the water. Although this chemical agent is beneficial for creating fractures, it will cause serious pollution to groundwater. In this method, the shock wave can create better fractures, so there is no need to add fracturing fluid, making it more environmentally friendly.

[0028] 3. The high-pressure, high-temperature gas generated by this method will not be conducted to the coal seam through water. Under the action of the shock wave and pressurized water, the coal body will only experience damage and desorption of gas. Therefore, this method has better safety compared to blasting. This method uses an intrinsically safe explosion shock wave generator that will not produce sparks, meaning it can still operate during gas extraction, significantly improving work efficiency.

[0029] 4. The setting of measuring holes (i.e., small boreholes) can digitally present coal and rock damage, and can effectively control the damage to coal and rock. It can achieve sufficient pre-splitting, ensure thorough gas dissipation, and ensure unobstructed gas production channels. At the same time, it can avoid excessive damage to the rock mass, which could lead to unstable support and mine pressure accidents.

[0030] In summary, this invention discloses a high-temperature, high-pressure gas deep-hole pre-hydraulic pressure conduction explosive shock wave fracturing device and method. A borehole of 20m-50m is drilled in the protective coal seam. An explosive shock wave generator produces a shock wave that is transmitted to the bottom of the borehole through a stainless steel pipe. High-pressure water is filled into the borehole and the stainless steel pipe to achieve coupling between the explosive shock wave and water, enabling more efficient pre-fracture of the protective layer. A sealing ring is used to seal the water, and an acoustic loss measurement probe is used to measure the wave velocity, which is used to evaluate the fracturing effect. Water coupling is also required in the measuring borehole (i.e., the small borehole) to improve the accuracy of the measurement results. The measuring borehole is sealed with a water-stop plug. This invention, using explosive shock wave-water coupling to fracturing coal seams, achieves better fracturing results while being safer and more environmentally friendly. The long borehole replaces roadway construction, reducing the amount of construction work, and is suitable for protective layer pre-fracture mining. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the backward pre-cracking method of the present invention;

[0033] Figure 3 This is a schematic diagram of the sealing ring structure in this invention;

[0034] Figure 4 This is a schematic diagram of the sealing structure in this invention;

[0035] Figure 5 This is a schematic diagram of the water stop plug in this invention. Detailed Implementation

[0036] The invention will now be further described with reference to the accompanying drawings.

[0037] Example 1:

[0038] like Figure 1 As shown, a device for fracturing deep-hole gas under high temperature and high pressure with advanced water pressure conduction of explosive shock wave includes a pipe body 3. The end of the pipe body 3 is connected to an explosive shock wave generator 6. A valve for opening and closing is provided between the pipe body 3 and the explosive shock wave generator 6. A sealing ring 4 is movably installed on the pipe body 3, meaning that the position of the sealing ring 4 on the pipe body 3 is adjustable. The pipe body 3 is made of stainless steel.

[0039] like Figure 3 As shown, the sealing ring 4 includes an inlet end 41, an expansion part 42, and an outlet end 43 connected in sequence; the expansion part 42 is a water bladder; the inlet end 41 is provided with an inlet A 44 and an inlet B 45; the outlet end 43 is provided with an outlet 46; the inlet B 45 and the outlet 46 are connected.

[0040] like Figure 4 As shown, inlet A 44, inlet B 45, and outlet 46 are all equipped with sealing structures 47. The sealing structure 47 includes threaded grooves 471 on the inlet end 41 and outlet end 43. A through hole is formed in the center of the bottom of the threaded groove 471, penetrating both the inlet end 41 and outlet end 43. A perforated nut 472 is fitted inside the threaded groove 471, and a perforated sealing gasket 473 is placed at the bottom of the threaded groove 471. The water pipe 474 passes sequentially through the perforated nut 472, the perforated sealing gasket 473, and the through hole. A plug is movably installed on the water pipe 474 at both inlet A 44 and inlet B 45; the plug is removable. The perforated sealing gasket 473 is made of silicone material, has a certain degree of elasticity, and can be reused. The water pipe 474 is a stainless steel water pipe.

[0041] The fracturing device in this embodiment also includes an acoustic detection device 2, which includes a hollow rod body 21 with a sealed head, four acoustic damage measurement probes 22 evenly distributed inside the hollow rod body 21, and a coupling agent water filling the hollow rod body 21. The end opening of the hollow rod body 21 is sealed by a water-stop plug 23. The hollow rod body 21 is a steel rod.

[0042] like Figure 5 As shown, the stop plug 23 includes an expansion portion 231, which is covered with an external elastic layer 232. An adhesive portion 233 is located between the expansion portion 231 and the external elastic layer 232. A coupling agent inlet 234 is provided on the expansion portion 231. In this embodiment, the expansion portion 231 is made of existing wear-resistant rubber. When coupling agent needs to be filled, it is added through the coupling agent inlet 234. After filling, the coupling agent inlet 234 on the expansion portion 231 is compressed by the expansion portion 231 and returns to its initial state, preventing coupling agent leakage. The external elastic layer is made of rubber, preferably fluororubber, which is oil-resistant, chemically resistant, and has good elasticity. The adhesive portion 233 is bonded using polyurethane adhesive, which is waterproof, impermeable, and has strong adhesion.

[0043] The outer surface of the expansion part 42 is machined with diagonal lines, which can increase the friction with the hole wall.

[0044] The outer surface of the tube body 3 is machined with diagonal lines to increase friction and allow for better contact and sealing with the sealing ring 4.

[0045] The fracturing device and fracturing method using the orifice high-temperature high-pressure gas deep hole advanced water pressure conduction explosion shock wave fracturing method of this embodiment include the following operation steps:

[0046] Step A: Drill a large borehole with a diameter of 140mm and a length of 20m in the middle of the coal seam thickness at the working face using a drilling machine, and drill a small borehole with a diameter of 60mm and a length of 20m at a horizontal distance of 5m on both sides. Rinse all long boreholes (including one large borehole and two small boreholes) with clean water to remove coal dust.

[0047] Step B: Install the explosion shock wave generator 6. Figure 1 The main body 3 of the middle tube extends into the bottom of the 140mm borehole. After the main body 3 of the tube and the explosive shock wave generator 6 are connected, check whether the valve switch is closed. Put the sealing ring 4 on the stainless steel tube 3 and insert it into the large borehole to a depth of 15m.

[0048] Step C: Fill the expansion part 42 of the sealing ring 4 with water through the inlet A44 until the pressure reaches 2.5MPa, the length of the sealing ring reaches 1.5m, and there is full contact between the sealing ring and the hole wall to achieve a sealing effect of 50MPa. Use a plug to block the inlet A44.

[0049] Step D: Fill the large borehole and pipe body 3 with water through the inlet B45 on the sealing ring 4 to reach a high pressure of 20MPa, and then use a plug to block the inlet B45.

[0050] Step E: Insert the acoustic detection device 2, which is equipped with 4 acoustic damage measurement probes 22, into the small drill holes on both sides. The 4 acoustic damage measurement probes 22 are located at hole depths of 5m, 10m, 15m and 20m respectively. Fill the hole with water as a coupling agent and use a water stop plug 23 to seal the water at the hole opening.

[0051] Step F: Use the explosion shock wave generator 6 to generate an explosion shock wave. Open the valve between the pipe body 3 and the explosion shock wave generator 6. The explosion shock wave couples with the high-pressure water in the pipe body 3. Due to the incompressibility of water, the explosion shock wave is transmitted to the bottom of the hole to fracture the coal and rock. Use the acoustic wave damage measurement probe at 20m to observe the acoustic wave velocity until the wave velocity drops to V1, where V1 is the longitudinal wave velocity of the acoustic wave. In this embodiment, V1 is 1200m / s. After meeting the pre-fracture requirements, stop the explosion shock wave generator 6.

[0052] Step G: Unscrew the plug at inlet A44. After the sealing ring 4 fails, retract the pipe body 3 by 5m, insert the sealing ring 4 to a depth of 10m, and refill water through inlet A44 to a pressure of 2.5MPa. Figure 2 The process of repeating step DF as shown in the diagram continues until the next cycle is reached.

[0053] Since water is incompressible and essentially a rigid body, when the valve is opened, the high-temperature and high-pressure gas generated by the explosion shock wave generator 6 acts on the water. The water merely transmits the shock wave, which couples with the high-pressure water. The shock wave is then transmitted to the bottom of the borehole to fracture the coal and rock, thus achieving safe, efficient, clean, and pre-fractured mining of the protective layer.

[0054] This embodiment Figure 1 In the diagram, the roof 1 is the rock strata within a certain distance above the coal seam of the working face, and the floor 7 is the rock strata within a certain distance below the coal seam of the working face.

[0055] This embodiment Figure 2 This is a schematic diagram of a backward pre-splitting method, where 101 is an intact coal seam and 102 is a fractured coal seam.

[0056] Example 2:

[0057] like Figure 1 As shown, a device for fracturing deep-hole gas under high temperature and high pressure with advanced water pressure conduction of explosive shock wave includes a pipe body 3. The end of the pipe body 3 is connected to an explosive shock wave generator 6. A valve for opening and closing is provided between the pipe body 3 and the explosive shock wave generator 6. A sealing ring 4 is movably installed on the pipe body 3, meaning that the position of the sealing ring 4 on the pipe body 3 is adjustable. The pipe body 3 is made of stainless steel.

[0058] like Figure 3As shown, the sealing ring 4 includes an inlet end 41, an expansion part 42, and an outlet end 43 connected in sequence; the expansion part 42 is a water bladder; the inlet end 41 is provided with an inlet A 44 and an inlet B 45; the outlet end 43 is provided with an outlet 46; the inlet B 45 and the outlet 46 are connected.

[0059] like Figure 4 As shown, inlet A 44, inlet B 45, and outlet 46 are all equipped with sealing structures 47. The sealing structure 47 includes threaded grooves 471 on the inlet end 41 and outlet end 43. A through hole is formed in the center of the bottom of the threaded groove 471, penetrating both the inlet end 41 and outlet end 43. A perforated nut 472 is fitted inside the threaded groove 471, and a perforated sealing gasket 473 is placed at the bottom of the threaded groove 471. The water pipe 474 passes sequentially through the perforated nut 472, the perforated sealing gasket 473, and the through hole. A plug is movably installed on the water pipe 474 at both inlet A 44 and inlet B 45; the plug is removable. The perforated sealing gasket 473 is made of silicone material, has a certain degree of elasticity, and can be reused. The water pipe 474 is a stainless steel water pipe.

[0060] The fracturing device in this embodiment also includes an acoustic detection device 2, which includes a hollow rod body 21 with a sealed head, five acoustic damage measurement probes 22 evenly distributed inside the hollow rod body 21, and the hollow rod body 21 is filled with coupling agent water. The end opening of the hollow rod body 21 is sealed by a water-stop plug 23. The hollow rod body 21 is a steel rod.

[0061] like Figure 5 As shown, the stop plug 23 includes an expansion portion 231, which is covered with an external elastic layer 232. An adhesive portion 233 is located between the expansion portion 231 and the external elastic layer 232. A coupling agent inlet 234 is provided on the expansion portion 231. In this embodiment, the expansion portion 231 is made of existing butyl rubber. When coupling agent needs to be filled, it is added through the coupling agent inlet 234. After filling, the coupling agent inlet 234 on the expansion portion 231 is compressed by the expansion portion 231 and returns to its initial state, preventing coupling agent leakage. The external elastic layer is made of rubber, preferably fluororubber, which is oil-resistant, chemically resistant, and has good elasticity. The adhesive portion 233 is bonded using polyurethane adhesive, which is waterproof, impermeable, and has strong adhesion.

[0062] The outer surface of the expansion part 42 is machined with diagonal lines, which can increase the friction with the hole wall.

[0063] The outer surface of the tube body 3 is machined with diagonal lines to increase friction and allow for better contact and sealing with the sealing ring 4.

[0064] The fracturing device and fracturing method using the orifice high-temperature high-pressure gas deep hole advanced water pressure conduction explosion shock wave fracturing method of this embodiment include the following operation steps:

[0065] Step A: Drill a large borehole with a diameter of 150mm and a length of 30m in the middle of the coal seam thickness at the working face using a drilling machine, and drill a small borehole with a diameter of 70mm and a length of 30m at the same horizontal distance of 6m on both sides. Rinse all long boreholes (including one large borehole and two small boreholes) with clean water to remove coal dust.

[0066] Step B: Install the explosion shock wave generator 6. Figure 1 The main body 3 of the middle tube extends into the bottom of the 150mm borehole. After the main body 3 of the tube and the explosive shock wave generator 6 are connected, check whether the valve switch is closed. Put the sealing ring 4 on the stainless steel tube 3 and insert it into the large borehole at a depth of 24m.

[0067] Step C: Fill the expansion part 42 of the sealing ring 4 with water through the inlet A44 until the pressure reaches 3MPa, the length of the sealing ring reaches 1.6m, and it is in full contact with the hole wall to achieve a sealing effect of 55MPa. Use a plug to block the inlet A44.

[0068] Step D: Fill the large borehole and pipe body 3 with water through the inlet B45 on the sealing ring 4 to reach a high pressure of 25MPa, and then use a plug to block the inlet B45.

[0069] Step E: Insert the acoustic detection device 2, which is equipped with 5 acoustic damage measurement probes 22, into the small drill holes on both sides. The 5 acoustic damage measurement probes 22 are located at hole depths of 6m, 12m, 18m, 24m, and 30m, respectively. Fill the holes with water as a coupling agent and use a water stop plug 23 to seal the water at the hole opening.

[0070] Step F: Use the explosion shock wave generator 6 to generate an explosion shock wave. Open the valve between the pipe body 3 and the explosion shock wave generator 6. The explosion shock wave couples with the high-pressure water in the pipe body 3. Due to the incompressibility of water, the explosion shock wave is transmitted to the bottom of the hole to fracture the coal and rock. Use the acoustic wave damage measurement probe at 30m to observe the acoustic wave velocity until the wave velocity drops to V1, where V1 is the longitudinal wave velocity of the acoustic wave. In this embodiment, V1 is 1200m / s. After meeting the pre-fracture requirements, stop the explosion shock wave generator 6.

[0071] Step G: Unscrew the plug at inlet A44. After the sealing ring 4 fails, retract the pipe body 3 by 6m, insert the sealing ring 4 to a depth of 18m, and refill water through inlet A44 to 3MPa. Figure 2 The process of repeating step DF as shown in the diagram continues until the next cycle is reached.

[0072] Example 3

[0073] The only difference between this embodiment and Embodiment 1 is that:

[0074] There are 8 acoustic damage testing probes 22.

[0075] A fracturing device and method for inducing fracturing in a deep hole with high-temperature and high-pressure gas at the orifice and advanced water pressure conduction of an explosion shock wave include the following steps:

[0076] Step A: Drill a large borehole with a diameter of 145mm and a length of 50m in the middle of the coal seam thickness at the working face using a drilling machine, and drill a small borehole with a diameter of 65mm and a length of 50m at the same horizontal distance on both sides. Rinse all long boreholes (including one large borehole and two small boreholes) with clean water to remove coal dust.

[0077] Step B: Install the explosion shock wave generator 6. Figure 1 The main body 3 of the middle tube extends into the bottom of the 145mm borehole. After the main body 3 of the tube and the explosive shock wave generator 6 are connected, check whether the valve switch is closed. Put the sealing ring 4 on the stainless steel tube 3 and insert it into the large borehole at a depth of 43.75m.

[0078] Step C: Fill the expansion part 42 of the sealing ring 4 with water through the inlet A44 until the pressure reaches 3.5MPa, the length of the sealing ring reaches 1.7m, and there is full contact between the sealing ring and the hole wall to achieve a sealing effect of 60MPa. Then, use a plug to block the inlet A44.

[0079] Step D: Fill the large borehole and pipe body 3 with water through the inlet B45 on the sealing ring 4 to reach a high pressure of 27MPa, and then use a plug to block the inlet B45.

[0080] Step E: Insert the acoustic detection device 2, which is equipped with 8 acoustic damage measurement probes 22, into the small drill holes on both sides. The 8 acoustic damage measurement probes 22 are located at hole depths of 6.25m, 12.5m, 18.75m, 25m, 31.25m, 37.5m, 43.75m, and 50m, respectively. Fill the hole with water as a coupling agent and use a water stop plug 23 to seal the water at the hole opening.

[0081] Step F: Use the explosion shock wave generator 6 to generate an explosion shock wave. Open the valve between the pipe body 3 and the explosion shock wave generator 6. The explosion shock wave couples with the high-pressure water in the pipe body 3. Due to the incompressibility of water, the explosion shock wave is transmitted to the bottom of the hole to fracture the coal and rock. Use the acoustic wave damage measurement probe at 50m to observe the acoustic wave velocity until the wave velocity drops to V1, where V1 is the longitudinal wave velocity of the acoustic wave. In this embodiment, V1 is 1200m / s. After meeting the pre-fracture requirements, stop the explosion shock wave generator 6.

[0082] Step G: Unscrew the plug at inlet A44. After the sealing ring 4 fails, retract the pipe body 3 by 6.25m, insert the sealing ring 4 to a depth of 37.5m, and refill water through inlet A44 to a pressure of 3.5MPa. Figure 2 The process of repeating step DF as shown in the diagram continues until the next cycle is reached.

[0083] Comparative example:

[0084] Retreating segmented hydraulic fracturing pre-fracturing protective layer:

[0085] a. Use a drilling rig to construct multiple fracturing boreholes, each 20m deep, one by one within the protective coal and rock mass;

[0086] b. Using multiple fracturing-specific installation rods connected together, the sealing device is inserted into multiple fracturing boreholes to a depth of 3-16m from the borehole opening for sealing; the connection method of the connected fracturing-specific installation rods is threaded connection or quick coupling connection.

[0087] c. Install water injection pipelines connected to the fracturing-specific installation rods at the openings of multiple fracturing boreholes. At the same time, install shut-off valves and pressure gauges on the water injection pipelines at the openings of each fracturing borehole. Connect the water injection pipelines together using equal flow dividers and connect them to the water injection pump through the equal flow dividers.

[0088] d. Start the water injection pump, adjust the equal flow divider, and continuously inject water into the sealing holes of one or more fracturing boreholes through the fracturing-specific installation rod to perform one cycle of hydraulic fracturing; when the water injection pressure of one or more water injection pipelines is less than 1MPa as monitored by the pressure gauge, close the shut-off valves on one or more water injection pipelines; when the water injection pressure of all water injection pipelines is less than 1MPa as monitored by the pressure gauge, turn off the water injection pump to complete this cycle of hydraulic fracturing.

[0089] e. After depressurizing the sealing device, move it out 1-15m towards the fracturing borehole opening, repeat step d, and perform another cycle of hydraulic fracturing.

[0090] f. Repeat step e multiple times until the sealing device retracts to a depth of 1-15m from the borehole opening for the final hydraulic fracturing cycle, followed by the retraction segmented hydraulic fracturing.

[0091] Compared with the comparative example, the high-temperature and high-pressure gas deep hole pre-hydraulic pressure conduction explosion shock wave fracturing method of the present invention has the following advantages:

[0092] 1. This method is significantly more efficient than hydraulic fracturing. Shock waves can generate radial and circumferential fractures, while hydraulic fracturing can only produce a single radial fracture. Circumferential fractures are distributed within 1m of the borehole diameter. These complex, fine fractures are highly conducive to gas desorption, forming gas-producing channels. Meanwhile, the relatively large radial fractures serve as the main gas channels connecting the fine fractures. Therefore, this method can greatly improve the gas extraction rate while effectively pre-fractured protective layers.

[0093] 2. This method uses an intrinsically safe explosive shock wave generator and pressurized water as the medium for transmitting the shock wave. Compared with hydraulic fracturing, it is more environmentally friendly because hydraulic fracturing adds fracturing fluid to the water. Although this chemical agent is beneficial for creating fractures, it will cause serious pollution to groundwater. In this method, the shock wave can create better fractures, so there is no need to add fracturing fluid, making it more environmentally friendly.

[0094] 3. The high-pressure, high-temperature gas generated by this method will not be conducted to the coal seam through water. Under the action of the shock wave and pressurized water, the coal body will only experience damage and desorption of gas. Therefore, this method has better safety compared to blasting. This method uses an intrinsically safe explosion shock wave generator that will not produce sparks, meaning it can still operate during gas extraction, significantly improving work efficiency.

[0095] 4. The setting of measuring holes (i.e., small boreholes) can digitally present coal and rock damage, and can effectively control the damage to coal and rock. It can achieve sufficient pre-splitting, ensure thorough gas dissipation, and ensure unobstructed gas production channels. At the same time, it can avoid excessive damage to the rock mass, which could lead to unstable support and mine pressure accidents.

[0096] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0097] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. 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. Therefore, they should not be construed as limitations on this invention.

[0098] Similarly, it should be understood that, in order to streamline this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0099] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hole high-temperature high-pressure gas deep hole advanced water pressure conduction explosion shock wave fracturing device, characterized in that: The device comprises a pipe body (3), the end of which is connected with an explosion shock wave generating device (6), a sealing ring (4) is movably arranged on the pipe body (3), the pipe body (3) penetrates through the sealing ring (4) and can move along the axial direction thereof; the sealing ring (4) comprises a water inlet end (41), an expansion part one (42) and a water outlet end (43) which are integrally connected in sequence; the water inlet end (41) is provided with a water inlet A (44) and a water inlet B (45); the water outlet end (43) is provided with a water outlet (46); the water inlet B (45) and the water outlet (46) are communicated and form a water injection channel which is independent of the expansion part one (42); the water inlet A (44), the water inlet B (45) and the water outlet (46) are all provided with a sealing structure (47); the sealing structure (47) is configured to realize a dynamic seal of not less than 50 MPa during the working process of the device; the sealing structure (47) comprises a threaded groove (471) arranged on the water inlet end (41) and the water outlet end (43), a through hole penetrating through the water inlet end (41) and the water outlet end (43) is formed in the middle of the groove bottom of the threaded groove (471), a threaded nut (472) is fitted in the threaded groove (471), a threaded sealing gasket (473) is placed on the groove bottom of the threaded groove (471), and a water pipe (474) penetrates through the threaded nut (472), the threaded sealing gasket (473) and the through hole in sequence; the water pipe (474) on the water inlet A (44) and the water inlet B (45) is movably provided with a plug; Wherein, the expansion part (42) expands to a length of ≥1.5m and the contact pressure between the expansion part (42) and the borehole wall is ≥50MPa when the water injection pressure reaches at least 2.5MPa.

2. The orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to claim 1, characterized in that: Further comprising a sound wave detection device (2), the sound wave detection device (2) comprises a head-sealed empty rod body (21), a plurality of sound wave detection probes (22) are uniformly distributed in the empty rod body (21), the empty rod body (21) is filled with a coupling agent, and the opening at the end of the empty rod body (21) is sealed by a water stop plug (23).

3. The orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to claim 2, characterized in that: The water stop plug (23) comprises an expansion part two (231), the outside of the expansion part two (231) is covered with an external elastic layer (232), and the expansion part two (231) and the external elastic layer (232) are bonded at a bonding site (233), and the expansion part two (231) is provided with a coupling agent inlet (234).

4. The orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to claim 1, characterized in that: A valve is arranged between the pipe body (3) and the explosion shock wave generating device (6) for opening and closing.

5. The orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to claim 1, characterized in that: The outer surfaces of the expansion part one (42) and the pipe body (3) are both provided with diagonal lines.

6. The orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to claim 3, characterized in that: The material of the external elastic layer (232) is rubber, and the material of the expansion part two (231) is wear-resistant rubber.

7. The orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to claim 3, characterized in that: The bonding site (233) is bonded by using polyurethane glue.

8. The orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to claim 2, characterized in that: The pipe body (3) is a stainless steel pipe, the empty rod body (21) is a steel rod, and the water pipe (474) is a stainless steel water pipe.

9. The orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to claim 2, characterized in that: The coupling agent comprises water.

10. A fracturing method using the orifice high-temperature high-pressure gas deep-hole advanced water pressure conduction explosion shock wave fracturing device according to any one of claims 2-9, characterized in that: The device comprises the following steps: Step A, using a drilling machine to drill a large borehole with a diameter of 140-150 mm and a length of 20-50 m in the middle of the working face coal seam thickness, and drill a small borehole with a diameter of 60-70 mm and a length of 20-50 m at a horizontal distance of 5-6 m on both sides, all long boreholes are washed with clean water to remove coal powder; Step B, install the explosion shock wave generating device (6) with the pipe body (3), extend the pipe body (3) into the bottom of the large borehole, check whether the valve switch is closed after the pipe body (3) and the explosion shock wave generating device (6) are connected, put the sealing ring (4) on the pipe body (3), the distance between the sealing ring (4) and the bottom of the large borehole is 5-6.25 m; Step C, fill water into the expansion part one (42) through the water inlet A (44) on the sealing ring (4) until the pressure reaches at least 2.5 MPa, the length of the sealing ring (4) reaches at least 1.5 m, and the sealing ring (4) and the hole wall of the large borehole are in full contact to achieve a sealing effect of at least 50 MPa, use a plug to plug the water inlet A (44); Step D, fill water into the large borehole and the pipe body (3) through the water injection channel composed of the water inlet B (45) and the water outlet (46) on the sealing ring (4) to reach a high pressure state, the pressure is at least 20 MPa, use a plug to plug the water inlet B (45); Step E, insert the acoustic wave detection device (2) with several acoustic wave damage detection probes (22) into the small boreholes on both sides, all acoustic wave damage detection probes (22) are evenly distributed in the small boreholes, and the positions of the acoustic wave damage detection probes (22) are matched with the positions of the sealing ring (4) in each pre-splitting; fill the coupling agent, and use the water stop plug (23) to seal the water at the hole of the empty rod body (21); Step F, use the explosion shock wave generating device (6) to generate an explosion shock wave, open the valve between the pipe body (3) and the explosion shock wave generating device (6), the explosion shock wave is coupled with the water in the pipe body (3), due to the incompressibility of water, the explosion shock wave is transmitted to the bottom of the large borehole to crack the coal rock, the acoustic wave velocity is observed using the acoustic wave damage detection probe (22) at the corresponding position, and the acoustic wave longitudinal wave velocity V1 falling to 1200 m / s or below is used as the quantitative judgment standard for the coal seam to meet the pre-splitting requirement, stop the explosion shock wave generating device (6) after meeting the pre-splitting requirement; Step G, unscrew the plug of the water inlet A (44), after the sealing ring (4) is disabled, retract the pipe body (3) by 5-6.25 m, re-inject water through the water inlet A (44) to at least 2.5 MPa, and repeat steps D-F to reach the next cycle.

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