Coal mine downhole sandblasting, perforating and fracturing integrated operation tool with external pressure control

Abstract

The application discloses a coal mine underground sand-blasting, perforating and fracturing integrated operation tool with external pressure control, which comprises upper sealing joints, a sealing inner tube, a lower sealing joint of the sealing inner tube, a gun barrel, a lower sealing joint, a lower packer and a bottom plug which are sequentially connected, and an upper packer which is sleeved on the outside of the sealing inner tube. The internal through holes of the series connection components are communicated to form a main working liquid channel, and an expansion cavity is formed between the inner wall of the upper packer and the outer wall of the sealing inner tube. The side of the upper sealing joint is provided with a pressure control liquid path interface, which is communicated with the expansion cavity through a pressure control channel arranged in the inside of the upper sealing joint and is used for connecting an independent pressure source. In the sand-blasting and perforating stage, the upper packer remains contracted, and the working liquid returns along the outside annulus thereof; in the fracturing stage, pressure is supplied to the expansion cavity to make the upper packer expand, and the upper packer and the lower packer jointly seal the operation section. The application realizes independent control of the setting pressure of the upper packer and the main flow pressure of the sand-blasting and perforating.

Description

Technical Field

[0001] This invention relates to the field of coal seam permeability enhancement and gas extraction operations in underground coal mines, specifically to an integrated tool for underground sandblasting, perforation, and fracturing operations with external pressure control. Background Technology

[0002] In coal mine operations involving the control of low-permeability coal seam gas and coalbed methane extraction, hydraulic jetting perforation can create perforation channels in the near-wellbore area of ​​the coal seam, while hydraulic fracturing can further expand the fractures based on the perforations. To reduce repeated tripping of tubing strings, the jetting nozzle and packer are usually combined into a single downhole tool, with the jetting and fracturing fluids transported to the nozzle through the same main working fluid channel. The jetting perforation stage requires maintaining an annular backflow channel above the nozzle, while the fracturing stage requires the formation of a packer above the nozzle; the requirements for the packer's condition are opposite in these two stages.

[0003] In existing tools, the packer above the spray gun typically uses the pressure from the main working fluid channel for setting, meaning its expansion chamber is connected to the mainstream pressure. In this configuration, because the main working fluid channel is already under high pressure during the sandblasting and perforation stage, the upper packer expands and sets synchronously during sandblasting, making it impossible to maintain contraction during the sandblasting stage to preserve the wellbore annulus outside the upper packer. If the mainstream pressure is reduced to avoid setting during the sandblasting stage, the high-pressure jet requirement of sandblasting and perforation cannot be met. Therefore, the setting pressure of the upper packer passively depends on the pressure of the main working fluid channel, and its setting state cannot be actively switched according to the needs of the operational stage. This results in the inability to maintain contraction during the sandblasting stage and the inability to independently control the setting timing during the fracturing stage. Consequently, the opposing state requirements of the upper packer for both the sandblasting and perforation stages cannot be met simultaneously under the same pressure source. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated underground coal mine sandblasting, perforation, and fracturing tool with external pressure control. Through a high-pressure hose, a one-way valve on the orifice side, and a pressure control channel located inside the upper sealing joint, pressure is supplied separately to the expansion cavity between the outer wall of the inner sealing tube and the inner wall of the upper packer. This ensures that the setting action of the upper packer is not affected by the main working fluid pressure of the sandblasting and perforation, thereby preserving the upper annular backflow channel during the sandblasting and perforation stage and forming a target operating section with upper and lower double packers during the fracturing stage.

[0005] The technical solution of this invention is: An integrated sandblasting, perforation, and fracturing tool for coal mines with external pressure control includes, from top to bottom, an upper sealing joint, a sealing inner tube, a lower joint of the sealing inner tube, a spray gun barrel, a lower sealing joint, a lower packer, and a bottom plug, all coaxially connected. An upper packer is fitted over the sealing inner tube and located above the spray gun barrel. The lower joint of the sealing inner tube is located between the sealing inner tube and the spray gun barrel, and the lower sealing joint is located between the spray gun barrel and the lower packer.

[0006] The upper sealing joint, the inner sealing tube, the lower joint of the inner sealing tube, the spray gun barrel, the lower sealing joint, and the lower packer are connected in sequence to form the main working fluid channel. The inner cavity of the spray gun barrel is connected to the main working fluid channel. The sandblasting nozzle on the side wall of the spray gun barrel is used to spray high-pressure sand-containing working fluid or fracturing fluid into the target coal seam.

[0007] The upper packer is a radially expandable elastic rubber packer fitted outside the inner sealing tube. An expansion cavity is formed between the inner wall of the upper packer and the outer wall of the inner sealing tube. The main working fluid channel is located inside the inner sealing tube, and the expansion cavity is located outside the inner sealing tube, with the two mutually sealing and isolating each other. The lower connector of the inner sealing tube connects the inner sealing tube to the spray gun barrel and cooperates with the end sealing structure at the lower end of the upper packer to seal and limit the lower end of the expansion cavity.

[0008] The upper sealing joint has a pressure-controlled fluid interface on its side. Inside the upper sealing joint is a pressure-controlled channel communicating with the pressure-controlled fluid interface. The outlet of the pressure-controlled channel communicates with the expansion chamber of the upper packer. The pressure-controlled fluid interface is connected to the orifice side via a high-pressure hose arranged along the outside of the working tubing. A one-way valve is installed on the high-pressure hose and connected to an independent pressure-controlled pump or other pressure source. The high-pressure hose, the one-way valve on the orifice side, and the independent pressure-controlled pump constitute a complete pressure-controlled device.

[0009] During the sandblasting and perforation stage, the one-way valve on the orifice side remains closed, and no pressure is supplied to the expansion chamber of the upper packer, so the upper packer remains contracted; the lower packer maintains the lower sealing, and the high-pressure sand-laden working fluid enters the spray gun through the main working fluid channel and is sprayed out from the sandblasting nozzle. The working fluid that does not enter the coal seam and the sand-laden return fluid return to the orifice along the wellbore annulus outside the upper packer.

[0010] After the sandblasting perforation is completed and the fracturing stage begins, the one-way valve on the orifice side is opened and the independent pressure control pump is started. The pressure control fluid enters the expansion chamber sequentially through the high-pressure hose, the pressure control fluid interface, and the pressure control channel inside the upper sealing joint, causing the upper packer to expand radially outward and fit tightly against the well wall. At this time, the upper packer and the lower packer together seal the target working section where the spray gun is located, and then the fracturing fluid is pumped into the spray gun barrel through the main working fluid channel to complete the local fracturing.

[0011] Furthermore, the pressure control fluid interface is located on the side wall of the upper sealing joint and adopts a high-pressure interface that can be sealed and connected with the high-pressure hose; the pressure control channel inside the upper sealing joint bypasses the main working fluid channel, its inlet is connected to the pressure control fluid interface, and its outlet is connected to the expansion chamber outside the inner sealing tube.

[0012] Furthermore, the upper packer is made of pressure-resistant elastic rubber material, and its two ends are sealed and fixed to the inner sealing tube through end sealing structures. The lower joint of the inner sealing tube is located on one side of the lower end of the upper packer and cooperates with the end sealing structure to seal the lower end of the expansion chamber. After the pressure-controlled fluid enters the expansion chamber, it pushes the upper packer to expand radially, making its outer wall in close contact with the well wall. When it is necessary to retrieve the tool, the pressure in the expansion chamber is depressurized through the matching pressure control device, causing the upper packer to retract.

[0013] Furthermore, the lower packer located below the nozzle barrel is used to seal the wellbore annulus below the nozzle during the sandblasting and fracturing stages, and is distinct from the upper packer located above the nozzle barrel, which is controlled by an external pressure-controlled fluid circuit for expansion; the lower packer is not connected to the pressure control channel and expansion chamber of the upper packer.

[0014] Furthermore, multiple nozzle groups are arranged axially on the side wall of the spray gun barrel, each nozzle group including at least two sandblasting nozzles spaced apart circumferentially. The sandblasting nozzles can be detachably installed or interference-fitted, and their outlet ends can be provided with a tapered flare structure.

[0015] Furthermore, a continuous partition and a high-pressure resistant seal are installed between the main working fluid channel and the pressure control channel inside the upper sealing joint, and sealing rings are installed at the connection points of each adjacent connector to prevent cross-flow of sandblasting perforation fluid, fracturing fluid and upper packer pressure control fluid.

[0016] Furthermore, the high-pressure hose is arranged along the outside of the working string and is fixed to the working string by clamps or other fasteners; the downhole end of the high-pressure hose is detachably and sealed to the pressure control fluid interface on the side of the upper sealing joint, and the orifice end is connected to a one-way valve and an independent pressure control pump.

[0017] Furthermore, the bottom plug seals the lower end of the main working fluid channel, allowing the high-pressure working fluid entering the inner cavity of the spray gun barrel to be sprayed out through the sandblasting nozzle; the lower end of the bottom plug is equipped with a tapered guide structure to reduce the risk of scraping when the tool is lowered.

[0018] Furthermore, the high-pressure hose, the orifice-side one-way valve, and the independent pressure control pump are part of the supporting pressure control device; the attached diagram shows the downhole tool body and the pressure control fluid interface located on the side of the upper sealing joint, but does not limit the specific three-dimensional structure of the supporting pressure control device.

[0019] Compared with the prior art, the beneficial effects of the present invention are: This invention continuously supplies sandblasting or fracturing fluid to the spray gun through the main working fluid channel penetrating the tool. It also independently pressurizes the expansion chamber of the upper packer via an external high-pressure hose, a one-way valve on the orifice side, and a pressure control channel located inside the upper sealing joint, ensuring that the main working fluid pressure and the upper packer setting pressure do not interfere with each other. During the sandblasting perforation stage, the upper packer remains contracted, allowing working fluid that has not entered the coal seam and sand-carrying return fluid to return to the orifice along the upper annulus, preventing premature setting of the upper packer and resulting pressure buildup and sand accumulation. During the fracturing stage, independent pressure is applied from the orifice side to expand the upper packer, forming a closed target working section together with the lower packer, concentrating the fracturing fluid on the perforation location. The lower joint of the sealing inner tube is located between the sealing inner tube and the spray gun body, sealing the lower end of the upper packer's expansion chamber while maintaining the continuity of the main working fluid channel, thereby improving the reliability of the isolation between the main working fluid delivery and the independent pressure control of the upper packer. Attached Figure Description

[0020] Figure 1 This is a half-sectional view of the spray gun barrel of the present invention.

[0021] Figure 2 This is a three-dimensional structural diagram of the spray gun barrel of the present invention.

[0022] Figure 3 This is a front view of the bottom plug of the present invention.

[0023] Figure 4 This is a half-sectional view of the bottom plug of the present invention.

[0024] Figure 5 This is a three-dimensional structural diagram of the bottom plug of the present invention.

[0025] Figure 6 This is a front view of the upper sealing joint of the present invention.

[0026] Figure 7 This is a half-sectional view of the upper sealing joint of the present invention.

[0027] Figure 8 This is a three-dimensional structural diagram of the upper sealing joint and pressure control fluid circuit interface of the present invention.

[0028] Figure 9 This is a front view of the sealed inner tube of the present invention.

[0029] Figure 10 This is a half-sectional view of the sealing inner tube of the present invention.

[0030] Figure 11 This is a three-dimensional structural diagram of the sealed inner tube of the present invention.

[0031] Figure 12 This is a schematic diagram of the upper packer end face structure of the present invention.

[0032] Figure 13 This is a longitudinal half-sectional view of the upper packer of the present invention.

[0033] Figure 14 This is a schematic diagram of the three-dimensional assembly structure of the upper packer of the present invention.

[0034] Figure 15 This is a front view of the lower sealing joint of the present invention.

[0035] Figure 16 This is a half-sectional view of the lower sealing joint of the present invention.

[0036] Figure 17 This is a three-dimensional structural diagram of the lower sealing joint of the present invention.

[0037] Figure 18 This is an overall assembled end view of the present invention.

[0038] Figure 19 This is a partial sectional view of the overall assembly of the present invention.

[0039] Figure 20 This is a schematic diagram of the overall assembly three-dimensional structure of the present invention.

[0040] The components are: 1. Upper sealing joint, 2. Pressure control fluid interface, 3. Sealing inner tube, 4. Upper packer, 5. Expansion chamber, 6. Pressure control channel, 7. Lower joint of sealing inner tube, 8. Spray gun barrel, 9. Sandblasting nozzle, 10. Lower sealing joint, 11. Lower packer, 12. Bottom plug, and 13. Main working fluid channel. Detailed Implementation

[0041] The following is combined Figures 1 to 20 The specific embodiments of the present invention will be described in detail below. In the description of the present invention, it should be understood that the terms "upper", "lower", "inner", "outer", "axial", and "radial", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only used for the convenience of describing the present invention, and do not constitute a limitation on the installation direction of the structure of the present invention.

[0042] Example An integrated sandblasting, perforation, and fracturing tool for underground coal mines with external pressure control is suitable for directional drilling along formations, cross-formation drilling, and other operations requiring sandblasting, perforation, and localized fracturing in underground coal mines. Its core features include: sandblasting and perforation fluid and fracturing fluid are delivered through the main working fluid channel 13 inside the tool; the expansion of the upper packer 4 is individually controlled by a one-way valve on the orifice side, a high-pressure hose, a pressure-controlled fluid interface 2, and a pressure-controlled channel 6 located inside the upper sealing joint 1; the pressure-controlled fluid enters the expansion chamber 5 between the outer wall of the sealing inner tube 3 and the inner wall of the upper packer 4, with the two fluid paths mutually sealed and isolated.

[0043] like Figure 18 , Figure 19 and Figure 20 As shown, the tool, from top to bottom, includes an upper sealing joint 1, a sealing inner tube 3, a lower sealing inner tube joint 7, a spray gun barrel 8, a lower sealing joint 10, a lower packer 11, and a bottom plug 12. The upper packer 4 is fitted outside the sealing inner tube 3 and located above the spray gun barrel 8. The lower sealing inner tube joint 7 is located between the sealing inner tube 3 and the spray gun barrel 8, and the lower sealing joint 10 is located between the spray gun barrel 8 and the lower packer 11. The upper packer 4 is expanded by an independent pressure-controlled fluid circuit, and the lower packer 11 is used to maintain the wellbore annulus below the spray gun barrel 8 during sandblasting perforation and fracturing.

[0044] like Figure 6 , Figure 7 and Figure 8 As shown, the upper sealing joint 1 is a hollow connection structure, with its central through hole forming part of the main working fluid channel 13. Its upper end connects to the working tubing, and its lower end connects to the inner sealing tube 3. A pressure-controlled fluid interface 2 is provided on the side of the upper sealing joint 1. Figure 8 The upper sealing joint 1 is provided with a pressure control channel 6 that communicates with the pressure control fluid interface 2. The pressure control channel 6 bypasses the central through hole and leads to the expansion cavity 5 outside the sealing inner tube 3. The outer end of the pressure control fluid interface 2 is used for a sealed connection with the high pressure hose.

[0045] like Figure 9 , Figure 10 and Figure 11 As shown, the inner sealing tube 3 is a hollow tubular structure, forming a main working fluid channel 13 inside. An upper packer 4 is fitted over the outer side of the inner sealing tube 3. The upper packer 4 is a radially expandable elastic rubber packer, and a closed expansion cavity 5 is formed between the inner wall of the upper packer 4 and the outer wall of the inner sealing tube 3. The expansion cavity 5 is connected to the pressure control fluid interface 2 via a pressure control channel 6 inside the upper sealing joint 1, and is isolated from the main working fluid channel 13 inside the inner sealing tube 3. The lower end of the inner sealing tube 3 is connected to the spray gun barrel 8 via a lower sealing tube joint 7. The lower sealing tube joint 7 maintains the continuity of the main working fluid channel 13 and cooperates with the end sealing structure at the lower end of the upper packer 4 to seal and limit the lower end of the expansion cavity 5.

[0046] like Figure 12 , Figure 13 and Figure 14 As shown, the upper packer 4 remains contracted when not pressurized, maintaining a backflow gap with the well wall. After the pressure-controlled fluid enters the expansion chamber 5, it expands radially outward and fits tightly against the well wall. The lower packer 11 is located below the nozzle barrel 8 and is used to maintain the annulus below the nozzle during the sandblasting and fracturing stages. The lower packer 11 is not connected to the pressure-controlled channel 6 or the expansion chamber 5 of the upper packer 4.

[0047] like Figure 1 and Figure 2 As shown, the spray gun barrel 8 is a hollow cylindrical structure, and its inner cavity is connected to the main working fluid channel 13. Multiple sets of sand-blasting nozzles 9 are arranged axially on the side wall of the spray gun barrel 8. High-pressure sand-containing working fluid or fracturing fluid enters the inner cavity of the spray gun barrel 8 through the main working fluid channel 13 and is radially sprayed towards the target coal seam by the sand-blasting nozzles 9.

[0048] like Figure 3 , Figure 4 and Figure 5 As shown, the bottom plug 12 is connected to the lower end of the tool and seals the lower end of the main working fluid channel 13, allowing the high-pressure working fluid entering the inner cavity of the spray gun barrel 8 to be sprayed out through the sandblasting nozzle 9. The lower end of the bottom plug 12 is provided with a tapered guide structure to guide the tool through the wellbore narrowing section and the curved section.

[0049] like Figure 15 , Figure 16 and Figure 17 As shown, the lower sealing joint 10 is located between the spray gun barrel 8 and the lower packer 11, used to connect the spray gun barrel 8 and the lower packer 11, transmit axial load, and maintain the continuous seal of the main working fluid channel 13. The lower joint 7 of the sealing inner tube is located between the sealing inner tube 3 and the spray gun barrel 8, used to achieve a sealed connection and flow transition between the two. Sealing rings are provided at each adjacent connection to keep the main working fluid channel 13 sealed under the action of high-pressure sand-containing working fluid and fracturing fluid.

[0050] The orifice-side pressure control device includes a high-pressure hose, a one-way valve, and an independent pressure control pump. The high-pressure hose extends along the outside of the working string, with its downhole end connected to the pressure control fluid interface 2 on the side of the upper sealing joint 1, and its orifice-side end connected to the one-way valve and the independent pressure control pump. Since the high-pressure hose, one-way valve, and independent pressure control pump are external hydraulic connections and control components and do not participate in the coaxial assembly of the downhole tool body, therefore... Figures 1 to 20 Not shown in the diagram; the pressure control fluid interface 2 belongs to the downhole tool body and has been... Figure 8 The bid was successful.

[0051] The operation process of the tool in this embodiment is as follows: The first step is tool lowering and lower packer sealing. The tool is lowered into the target well section, aligning the nozzle body 8 with the coal seam to be modified, and the lower packer 11 located below the nozzle body 8 is kept in a lower packer state. At this time, the one-way valve on the orifice side remains closed, the independent pressure control pump does not supply pressure to the expansion chamber 5 of the upper packer 4, and the upper packer 4 remains in a contracted state.

[0052] The second step is sandblasting and perforation. High-pressure sand-laden working fluid is pumped into the main working fluid channel 13 from the working tubing. The working fluid passes sequentially through the upper sealing joint 1, the inner sealing tube 3, and the lower sealing tube joint 7 into the inner cavity of the spray gun barrel 8, and is then sprayed out at high speed through the sandblasting nozzle 9 to sandblast and perforate the target coal seam. Since the expansion chamber 5 of the upper packer 4 is isolated from the main working fluid channel 13, the high pressure in the main working fluid channel 13 will not cause the upper packer 4 to expand. The working fluid that does not enter the coal seam and the sand-laden return fluid return to the orifice along the annulus outside the upper packer 4, which is in a contracted state. The lower packer 11 maintains the sealing of the annulus below the spray gun barrel 8, thereby preventing the upper annulus from being blocked and causing pressure buildup.

[0053] The third step is to set the upper packer. After the sandblasting perforation is completed, the one-way valve is opened on the orifice side and the independent pressure-controlled pump is started. The pressure-controlled fluid enters the pressure-controlled fluid interface 2 on the side of the upper sealing joint 1 through the high-pressure hose, and then enters the expansion chamber 5 between the outer wall of the inner sealing tube 3 and the inner wall of the upper packer 4 through the pressure-controlled channel 6 inside the upper sealing joint 1. As the pressure in the expansion chamber 5 increases, the upper packer 4 expands radially outward and fits tightly against the well wall, so that the upper packer 4 and the lower packer 11 together seal the target working section where the spray gun barrel 8 is located.

[0054] The fourth step is fracturing and depressurization. After the upper packer 4 reaches the predetermined setting state, fracturing fluid continues to be pumped into the nozzle barrel 8 through the main working fluid channel 13 from the working tubing. Since the upper and lower sides of the target working section are sealed by the upper packer 4 and the lower packer 11 respectively, the fracturing fluid enters the perforation channel through the sandblasting nozzle 9 and forms and expands fractures in the coal seam. After fracturing is completed, the main working fluid supply is stopped; when it is necessary to retrieve the tool, the pressure is released through the pressure control device on the orifice side to the high-pressure hose and the expansion chamber 5 of the upper packer 4, causing the upper packer 4 to retract, so as to restore the upper annulus and retrieve the tool.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. All equivalent substitutions, simple modifications, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coal mine underground sandblasting, perforation, and fracturing integrated operation tool with external pressure control, characterized in that, It includes an upper sealing joint, a sealing inner tube, a lower joint of the sealing inner tube, a spray gun body, a lower sealing joint, a lower packer and a bottom plug, which are coaxially connected from top to bottom, as well as an upper packer that is sleeved on the outside of the sealing inner tube and located above the spray gun body; The upper sealing joint, the inner sealing tube, the lower sealing tube joint, the spray gun barrel, the lower sealing joint, and the lower packer's internal through holes are sequentially connected to form the main working fluid channel, and the side wall of the spray gun barrel is provided with a sandblasting nozzle; The upper packer is a radially expandable elastic rubber packer sleeved on the outside of the inner sealing tube. An expansion cavity is formed between the inner wall of the upper packer and the outer wall of the inner sealing tube. The main working fluid channel passes through the inner sealing tube and is sealed and isolated from the expansion cavity. The lower joint of the inner sealing tube maintains the continuous flow between the inner sealing tube and the spray gun body and seals and limits the lower end of the expansion cavity. The upper sealing joint is provided with a pressure-controlled liquid circuit interface and a pressure-controlled channel connected to the pressure-controlled liquid circuit interface. The outlet of the pressure-controlled channel is connected to the expansion chamber. The pressure-controlled liquid circuit interface is used to connect an independent pressure source to independently control the expansion and setting of the upper packer.

2. The integrated coal mine underground sandblasting, perforation, and fracturing tool with external pressure control as described in claim 1, characterized in that, The pressure-controlled fluid interface is located on the side wall of the upper sealing joint, and the pressure-controlled channel is located inside the upper sealing joint and bypasses the main working fluid channel.

3. The integrated coal mine underground sandblasting, perforation, and fracturing tool with external pressure control as described in claim 2, characterized in that, The pressure control fluid interface and the pressure control channel are both sealed and isolated from the main working fluid channel.

4. The integrated coal mine underground sandblasting, perforation, and fracturing tool with external pressure control as described in claim 1, characterized in that, The outer end of the pressure-controlled fluid circuit interface is a high-pressure interface, which is used to seal and connect with the high-pressure hose arranged along the outside of the working tubing. The orifice end of the high-pressure hose is connected to a one-way valve and an independent pressure-controlled pump.

5. The integrated underground sandblasting, perforation, and fracturing tool for coal mines with external pressure control as described in claim 1, characterized in that... The two ends of the upper packer are sealed and fixed to the inner sealing tube by an end sealing structure. The lower joint of the inner sealing tube is located on the lower side of the upper packer and cooperates with the end sealing structure to seal the lower end of the expansion cavity.

6. The integrated coal mine underground sandblasting, perforation, and fracturing tool with external pressure control as described in claim 1, characterized in that, The lower packer is not connected to the pressure control channel and the expansion chamber, and is used to maintain the isolation of the wellbore annulus below the spray gun barrel during the sandblasting and fracturing stages.

7. The integrated coal mine underground sandblasting, perforation, and fracturing tool with external pressure control as described in claim 1, characterized in that, The inner cavity of the spray gun barrel is connected to the main working fluid channel, and the sandblasting nozzle is connected to the inner cavity of the spray gun barrel; the bottom plug seals the lower end of the main working fluid channel so as to force the working fluid entering the inner cavity of the spray gun barrel to be sprayed out through the sandblasting nozzle.

8. The integrated coal mine underground sandblasting, perforation, and fracturing tool with external pressure control as described in claim 1, characterized in that, The sidewall of the spray gun barrel is provided with multiple sets of nozzles along the axial direction, and each set of nozzles includes at least two sandblasting nozzles distributed circumferentially.

9. The integrated underground sandblasting, perforation, and fracturing tool for coal mines with external pressure control as described in claim 1, characterized in that, A sealing ring is provided at the connection between the upper sealing joint, the inner sealing tube, the lower joint of the inner sealing tube, the spray gun body, the lower sealing joint, the lower packer, and the bottom plug.

10. The integrated coal mine underground sandblasting, perforation, and fracturing tool with external pressure control according to claim 1, characterized in that, The bottom end of the plug is provided with a tapered guide structure.

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