A downhole fracturing tool

Abstract

This invention provides a downhole fracturing tool, including an outer casing, a soluble ball seat, and a setting component for lowering the soluble ball seat into the outer casing. The soluble ball seat includes a seat body and a pressure-reducing ball pre-installed within the seat body. The seat body has a limiting part that engages with the outer casing, and an elastic component that drives the limiting part to extend and retract radially. When the soluble ball seat is lowered, the elastic component contracts and connects to the setting component, with the outer diameter of the limiting part being smaller than the inner diameter of the outer casing. When the soluble ball seat needs to be set, the elastic component disengages from the setting component and expands radially outward, with the outer diameter of the limiting part being larger than the inner diameter of the outer casing. This invention has advantages such as rapid and safe lowering, reliable setting, simple structure, and low safety risks.

Description

Technical Field

[0001] This invention relates to the field of oil and gas fracturing for enhanced production, and more particularly to a downhole fracturing tool. Background Technology

[0002] In the development of unconventional oil and gas resources such as tight oil and gas and shale gas, the bridge plug perforation combined operation process is an important means to increase production and improve recovery rate. It has the advantages of achieving large-volume and large-scale volumetric fracturing. The quality and performance of the bridge plug determines the success or failure of the fracturing operation and also affects the reservoir development effect. Existing bridge plugs have gradually evolved from cast iron bridge plugs and easy-drill bridge plugs to soluble bridge plugs. After the fracturing operation is completed, the main part of the soluble bridge plug dissolves in the downhole environment, which solves the problem of drilling and removal difficulties of conventional bridge plugs. However, the existing soluble bridge plugs still have the following problems: (1) The bridge plug setting structure is complex, and there is a risk of premature setting during the running process. The post-premature setting is difficult to handle; (2) The bridge plug setting requires the setting tool to provide a large load, and there is a situation of incomplete setting; (3) The ceramic particles or hard alloys embedded on the bridge plug slips are insoluble and remain in the well later, posing a safety hazard; (4) The bridge plug is limited by its structure and has a small inner diameter, which is not conducive to post-fracturing fluid drainage and production. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a downhole fracturing tool that can be quickly and safely installed, reliably set, and has a simple structure and low safety risks.

[0004] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0005] A downhole fracturing tool includes an outer casing, a soluble ball seat, and a setting component for lowering the soluble ball seat into the outer casing. The soluble ball seat includes a ball seat body and a pressure ball pre-installed within the ball seat body. The ball seat body is provided with a limiting part that engages with the outer casing, and an elastic component that drives the limiting part to extend and retract radially. When the soluble ball seat is lowered, the elastic component contracts and connects to the setting component, and the outer diameter of the limiting part is smaller than the inner diameter of the outer casing. When the soluble ball seat needs to be set, the elastic component disengages from the setting component and expands radially outward, and the outer diameter of the limiting part is larger than the inner diameter of the outer casing.

[0006] As a further improvement to the above technical solution:

[0007] The outer casing includes a casing body and a fracturing fitting component connected to the casing body. The fracturing fitting component includes an outer casing, an inner sliding sleeve, a sliding sleeve shear pin, a first soluble protective sleeve, and a second soluble protective sleeve. The outer casing has a fracturing hole. The inner sliding sleeve is installed at the fracturing hole position via the sliding sleeve shear pin. The inner sliding sleeve moves downward when the sliding sleeve shear pin is cut to open the fracturing hole. The first and second soluble protective sleeves are respectively limited and installed at both ends of the inner sliding sleeve and degrade after cementing operations to form a mounting groove that fits with the limiting part and an avoidance groove that provides space for the inner sliding sleeve to move downward.

[0008] The outer cover includes an outer cover body, an upper connector, and a lower connector. The upper connector and the lower connector are connected to both ends of the outer cover body. The seat hanging groove is formed by the upper connector and the inner sliding sleeve, and the clearance groove is formed by the lower connector and the inner sliding sleeve.

[0009] The outer sleeve includes at least two separate sections, with a fitting gap between adjacent sections to accommodate the limiting part, and adjacent sections are connected by a coupling.

[0010] The end of the setting component away from the soluble ball seat is connected to a perforating gun for perforating the outer tube, and the perforating gun is connected to a cable for pumping the soluble ball seat.

[0011] The elastic component includes a plurality of elastic ribs; the plurality of elastic ribs are arranged at circumferential intervals along the soluble ball seat to allow for contraction space when the elastic component is connected to the seated component.

[0012] A positioning element is provided between the elastic rib and the seat sealing component. The positioning element is located on the side of the limiting part closer to the seat sealing component. The positioning element is cut off when the soluble ball seat needs to be seated.

[0013] The seat sealing component includes an outer positioning sleeve and an inner positioning shaft that are sleeved together. The positioning element is located between the outer positioning sleeve and the elastic rib. The elastic rib abuts against the end face of the inner positioning shaft.

[0014] The lower end of the ball seat is provided with a rubber cup for sealing the annular space between the soluble ball seat and the outer tube.

[0015] There are at least two soluble ball seats, which are arranged at intervals along the axial direction of the outer sleeve; the inner side of the lower end of the ball seat body is provided with a plurality of return grooves for the return liquid after fracturing, which are arranged at intervals along the circumference of the ball seat body.

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] (1) This invention features a limiting part and an elastic component on the ball seat body. The elastic component drives the limiting part to extend and retract radially. During the insertion of the soluble ball seat, the elastic component contracts and connects with the setting component. The outer diameter of the limiting part is smaller than the inner diameter of the outer sleeve, allowing the soluble ball seat to be inserted into the well smoothly and quickly, avoiding the risk of premature setting. This ensures high insertion safety and reliability. Simultaneously, when the soluble ball seat needs to be set, the elastic component disengages from the setting component and expands radially outward. The outer diameter of the limiting part is larger than the inner diameter of the outer sleeve. At this time, the limiting part can cooperate with the outer sleeve to achieve rapid locking. Therefore, this invention ensures the smooth and reliable insertion of the soluble ball seat while achieving reliable and effective setting of the soluble ball seat during fracturing. Furthermore, it avoids the problems of complex structure and cumbersome operation of existing slip-anchored bridge plugs, offering a simple structure and easy operation.

[0018] (2) The present invention adopts the form of limiting part and outer sleeve limiting cooperation, so that the soluble ball seat can be effectively sealed without the need for squeezing the sitting and hanging mechanism and the rubber tube. It requires a small sitting and hanging load, has strong adaptability to sitting and hanging tools, and has high reliability of sitting and hanging construction.

[0019] (3) The present invention uses a soluble ball seat, which allows the tool to be completely dissolved or degraded after fracturing, achieving full-bore in the well. It does not require other fishing operations, is easy to operate and has low cost, and effectively meets the unlimited level and full-bore operation requirements of unconventional oil and gas reservoirs. At the same time, it effectively avoids the occurrence of insoluble material left in the well and high-strength material damaging the casing, greatly reducing the safety hazards in the later stage of fracturing.

[0020] (4) The present invention adopts the form of a soluble ball seat, which makes the internal diameter large, which is conducive to liquid backflow and avoids the problem of the existing slip structure limiting the small inner diameter of the bridge plug. It is convenient to directly discharge the liquid after pressure and put it into production. At the same time, it allows the working tubing to be used for comprehensive treatment of the wellbore in the later stage.

[0021] (5) The present invention pre-installs the pressure-blocking ball in the ball seat body and lowers it together with the ball seat body. This allows the soluble ball seat to be locked and hung, and fracturing operations can be carried out directly without dropping the ball at the wellhead. This simplifies the operation process, saves the liquid used to pump the pressure-blocking ball, and shortens the operation time.

[0022] Furthermore, this invention includes a fracturing assembly that connects to the casing body. A soluble ball seat can be used in conjunction with this assembly. Specifically, the soluble ball seat engages with the mounting groove of the fracturing assembly for rapid setting and sealing. Simultaneously, when the second soluble protective sleeve degrades and the sliding sleeve shear pin breaks, the inner sliding sleeve descends to open the fracturing hole, allowing for fracturing operations. This avoids the complex perforation and quick-perforation procedures required in existing methods, saving steps and simplifying operation. The inner sliding sleeve is installed at the fracturing hole location via the sliding sleeve shear pin, with the first and second soluble protective sleeves respectively positioned at both ends of the inner sliding sleeve, resulting in a simple and compact structure. This downhole fracturing tool of the present invention can achieve precise locking of the soluble ball seat and can also be used in conjunction with the fracturing assembly to perform fracturing operations. It can replace conventional bridge plugs for segmented fracturing operations, further improving the safety, reliability, and speed of fracturing operations. Attached Figure Description

[0023] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0024] Figure 1 This is a schematic diagram of the soluble ball seat of the present invention.

[0025] Figure 2 This is a schematic diagram showing the fit between the soluble ball seat and the sealing component of the present invention.

[0026] Figure 3 This is a schematic diagram of the downhole fracturing tool in Embodiment 1 of the present invention (soluble ball seat in the well).

[0027] Figure 4 This is a schematic diagram of the downhole fracturing tool in Embodiment 1 of the present invention (soluble ball seat in the hanging state).

[0028] Figure 5 This is a schematic diagram of the downhole fracturing tool in Embodiment 2 of the present invention (soluble ball seat in the well).

[0029] Figure 6 This is a schematic diagram of the downhole fracturing tool in Embodiment 2 of the present invention (soluble ball seat in the hanging state).

[0030] Figure 7 This is a schematic diagram of the structure of the fracturing assembly component of the present invention.

[0031] The labels in the diagram represent:

[0032] 1. Outer sleeve; 11. Sleeve body; 12. Fracturing mating component; 121. Outer sleeve; 1211. Outer sleeve body; 1212. Upper connector; 1213. Lower connector; 122. Inner sliding sleeve; 123. Sliding sleeve shear pin; 124. First soluble protective sleeve; 125. Second soluble protective sleeve; 126. Fracturing hole; 127. Sealing groove; 128. Clearance groove; 129. Sealing ring; 13. Split section; 14. Fitting clearance; 15. Coupling; 2. Soluble ball seat; 21. Ball seat body; 22. Pressure ball; 23. Limiting part; 24. Elastic component; 241. Elastic rib; 25. Positioning component; 26. Rubber cup; 27. Return groove; 3. Sealing component; 31. Outer positioning sleeve; 32. Inner positioning shaft; 4. Perforation gun; 5. Cable. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, but this does not limit the scope of protection of the present invention.

[0034] Example 1

[0035] Figures 1 to 4 An embodiment of the downhole fracturing tool of the present invention is shown, which can be widely applied to fracturing operations in various vertical wells, horizontal wells, and extended reach wells. In this embodiment, the downhole fracturing tool includes an outer casing 1, a soluble ball seat 2, and a setting component 3 for lowering the soluble ball seat 2 into the outer casing 1. The soluble ball seat 2 includes a ball seat body 21 and a pressure-retaining ball 22, which is pre-set inside the ball seat body 21. The ball seat body 21 is provided with a limiting part 23 and an elastic component 24. When the soluble ball seat 2 is set, the limiting part 23 engages with the outer casing 1 for limiting, and the elastic component 24 drives the limiting part 23 to extend and retract radially. When the soluble ball seat 2 is lowered, the elastic component 24 is in a contracted state and connected to the setting component 3, and the outer diameter of the limiting part 23 is smaller than the inner diameter of the outer casing 1. When the soluble ball seat 2 needs to be set, the elastic component 24 disengages from the setting component 3 and expands radially outward, and the outer diameter of the limiting part 23 is larger than the inner diameter of the outer casing 1.

[0036] This invention features a limiting part 23 and an elastic component 24 on the ball seat body 21. The elastic component 24 drives the limiting part 23 to extend and retract radially. During the lowering of the soluble ball seat 2, the elastic component 24 contracts and connects with the setting component 3. At this time, the outer diameter of the limiting part 23 is smaller than the inner diameter of the outer sleeve 1, allowing the soluble ball seat 2 to be lowered into the well smoothly and quickly, avoiding the risk of premature setting and ensuring high safety and reliability during lowering. Simultaneously, when the soluble ball seat 2 needs to be set, the elastic component 24 disengages from the setting component 3 and expands radially outward. The outer diameter of the limiting part 23 is larger than the inner diameter of the outer sleeve 1, allowing the limiting part 23 to engage with the outer sleeve 1 for rapid locking. Therefore, this invention ensures the smooth and reliable lowering of the soluble ball seat 2 while achieving reliable and effective setting during fracturing. Furthermore, it avoids the problems of complex structure and cumbersome operation associated with existing slip-anchored bridge plugs, offering a simple structure and easy operation.

[0037] The present invention adopts the form of limiting part 23 and outer sleeve 1 limiting cooperation, so that the soluble ball seat 2 can be effectively sealed without the need for squeezing the sitting and hanging mechanism and the rubber tube. It requires a small sitting and hanging load, has strong adaptability to sitting and hanging tools, and has high reliability of sitting and hanging construction.

[0038] This invention employs a soluble ball seat 2, which allows the tool to be completely dissolved or degraded after fracturing, achieving full-bore operation in the well. It eliminates the need for other retrieval operations, making it convenient and cost-effective. It effectively meets the operational requirements of unconventional oil and gas reservoirs for unlimited-level, full-bore operation. At the same time, it effectively avoids the occurrence of insoluble material left in the well and high-strength material damaging the casing, greatly reducing safety hazards in the later stages of fracturing.

[0039] The present invention adopts the form of soluble ball seat 2, which makes the internal diameter large, which is conducive to liquid backflow and avoids the problem of the existing slip structure limiting the inner diameter of the bridge plug. It is convenient to directly discharge the liquid after pressure and put it into production. At the same time, it allows the working string to be used for comprehensive treatment of the wellbore in the later stage.

[0040] The present invention pre-installs the pressure-holding ball 22 inside the ball seat body 21 and lowers it together with the ball seat body 21. This allows the soluble ball seat 2 to be locked and set in place, so that fracturing operations can be carried out directly without dropping balls at the wellhead. This simplifies the operation process, saves the liquid used to pump the pressure-holding ball 22, and shortens the operation time.

[0041] Furthermore, such as Figure 1 and Figure 2As shown, the elastic component 24 includes multiple elastic ribs 241. The multiple elastic ribs 241 are arranged at intervals along the circumference of the soluble ball seat 2 to leave a contraction space when the elastic component 24 is connected to the setting component 3, so that the elastic ribs 241 retract radially and the outer diameter of the limiting part 23 is reduced, so that the soluble ball seat 2 can be smoothly and quickly lowered into the well, ensuring that the limiting part 23 does not rub against the outer casing 1 when entering the well, avoiding the risk of premature setting of the soluble ball seat 2, and its lowering safety and reliability are high.

[0042] Furthermore, a positioning element 25 is provided between the elastic rib 241 and the setting component 3. The positioning element 25 is located on the side of the limiting part 23 closer to the setting component 3. The positioning element 25 is cut off when the soluble ball seat 2 needs to be set, so that the elastic component 24 can be disengaged from the setting component 3. At this time, the elastic component 24 expands radially outward, and the limiting part 23 contacts the inner wall of the outer sleeve 1. When the limiting part 23 passes through the limiting area of ​​the outer sleeve 1, it can cooperate with the limiting part of the outer sleeve 1 to achieve quick locking. It is convenient to operate and has a simple structure.

[0043] like Figure 2 As shown, the setting component 3 includes an outer positioning sleeve 31 and an inner positioning shaft 32 that are nested together. A positioning element 25 is disposed between the outer positioning sleeve 31 and the elastic rib 241, with the elastic rib 241 abutting against the end face of the inner positioning shaft 32. This effectively fixes the position of the soluble ball seat 2 when it is lowered, ensuring reliable lowering of the soluble ball seat 2. Simultaneously, when the soluble ball seat 2 needs to be set, the outer positioning sleeve 31 shears off the positioning element 25 under the action of gunpowder, thus releasing the setting component 3 from the soluble ball seat 2.

[0044] Furthermore, a rubber cup 26 is provided at the lower end of the ball seat 21 to seal the annular space between the soluble ball seat 2 and the outer sleeve 1, preventing fluid from entering other fracturing layers and ensuring fracturing effect. In this embodiment, a placement groove is provided on the outer surface of the ball seat 21, and the rubber cup 26 is vulcanized and placed in the placement groove; at the same time, there are two rubber cups 26, which are arranged at intervals along the axial direction of the ball seat 21. In other embodiments, the number of rubber cups 26 can be adjusted according to the actual situation, such as one, three, four, etc.

[0045] In this embodiment, there are at least two soluble ball seats 2, which are arranged at intervals along the axial direction of the outer sleeve 1 to perform fracturing operations on different formations. The inner side of the lower end of the ball seat body 21 is provided with multiple return grooves 27, which are arranged at intervals along the circumference of the ball seat body 21. When fluid needs to be returned after fracturing, when the lower pressure ball 22 moves up to the top of the upper ball seat body 21, the returned fluid can be returned through the return grooves 27.

[0046] like Figure 3 and Figure 4As shown, the outer sleeve 1 includes at least two separate segments 13, with a fitting gap 14 between adjacent segments 13, and the adjacent segments 13 are connected by a coupling 15. In this embodiment, the width of the fitting gap 14 is greater than the width of the limiting part 23, so that when the limiting part 23 moves down, it can spring into the fitting gap 14 to achieve positioning and locking.

[0047] In this embodiment, a perforating gun 4 is connected to the end of the setting component 3 away from the soluble ball seat 2. The perforating gun 4 is used to perforate the outer casing 1. At the same time, the perforating gun 4 is connected to a cable 5 so that the perforating gun 4 is energized to achieve the perforating operation while the soluble ball seat 2 is being pumped.

[0048] In this embodiment, the ball seat 21 and the pressure ball 22 are made of soluble magnesium-aluminum alloy or biodegradable polymer materials such as polyhydroxyacetic acid and polylactic acid, and the rubber cup 26 is made of soluble rubber.

[0049] In this embodiment, the operation procedure for downhole fracturing tools is as follows:

[0050] (1) Assemble the perforating gun 4, the setting component 3 and the soluble ball seat 2 on the ground, and connect the soluble ball seat 2 and the setting component 3 through the positioning component 25; then, measure the outer diameter of the limiting part 23 of the soluble ball seat 2 to ensure that the limiting part 23 of the soluble ball seat 2 will not scrape against the inner wall of the outer sleeve 1 when it is lowered.

[0051] (2) Using cable 5, the setting component 3 and the soluble ball seat 2 are pumped. When the soluble ball seat 2 is pumped to the upper part of the fitting gap 14, the setting component 3 is activated. The outer positioning sleeve 31 is sheared off the positioning part 25 under the action of gunpowder. At this time, the setting component 3 and the soluble ball seat 2 are released. The limiting part 23 of the soluble ball seat 2 rebounds to contact the inner wall of the outer sleeve 1. The pumped liquid pushes the soluble ball seat 2 downward. When the soluble ball seat 2 reaches the fitting gap 14, the limiting part 23 of the soluble ball seat 2 springs into the fitting gap 14 to achieve locking.

[0052] (3) Raise the perforating gun 4 to a certain position and perform perforation on the outer sleeve 1 of the soluble ball seat 2. After perforation is completed, remove the perforating gun 4 and the setting component 3.

[0053] (4) After the fracturing operation of the upper reservoir of the soluble ball seat 2 is completed, repeat (1) to (3) and carry out the fracturing operation of each section of the upper part in sequence.

[0054] (5) After all fracturing operations are completed, liquid is flowed back, and the soluble ball seat 2 dissolves or degrades in the downhole environment.

[0055] Example 2

[0056] Figures 5 to 7Another embodiment of the downhole fracturing tool of the present invention is shown. This embodiment is basically the same as the previous embodiment, except that the segmented arrangement of the outer casing 1 is eliminated. Instead, the outer casing 1 is set as the casing body 11 and the fracturing mating component 12, which is connected to the casing body 11. In this embodiment, the fracturing mating component 12 includes an outer casing 121, an inner sliding sleeve 122, a sliding sleeve shear pin 123, a first soluble protective sleeve 124, and a second soluble protective sleeve 125. The outer sleeve 121 is provided with a fracturing hole 126. The inner sliding sleeve 122 is installed at the position of the fracturing hole 126 by a sliding sleeve shear pin 123. When the sliding sleeve shear pin 123 cuts, the inner sliding sleeve 122 moves downward to open the fracturing hole 126. The first soluble protective sleeve 124 and the second soluble protective sleeve 125 are respectively limited and installed at both ends of the inner sliding sleeve 122 and degraded after cementing operation to form a mounting groove 127 and a clearance groove 128. The mounting groove 127 is used to limit and cooperate with the limiting part 23, and the clearance groove 128 provides space for the inner sliding sleeve 122 to move downward.

[0057] The present invention is provided with a fracturing fitting component 12 connected to the casing body 11. The soluble ball seat 2 can be used in conjunction with the fracturing fitting component 12. Specifically, the soluble ball seat 2 can be limited and fitted with the sitting groove 127 of the fracturing fitting component 12 to achieve rapid setting and sealing. At the same time, when the second soluble protective sleeve 125 degrades and the sliding sleeve shear pin 123 is cut, the inner sliding sleeve 122 will descend to open the fracturing hole 126 so that fracturing operations can be carried out. This avoids the problem of the complicated perforation and quick perforation process required by the existing method, and saves process and is convenient to operate.

[0058] Meanwhile, the inner sliding sleeve 122 is installed at the fracturing hole 126 via the sliding sleeve shear pin 123. The first soluble protective sleeve 124 and the second soluble protective sleeve 125 are respectively limited and installed at both ends of the inner sliding sleeve 122, resulting in a simple and compact structure. The downhole fracturing tool of the present invention can achieve precise locking of the soluble ball seat 2 and can cooperate with the fracturing engagement component 12 to carry out fracturing operations. It can replace conventional bridge plugs for segmented fracturing operations, further improving the safety, reliability, and speed of fracturing operations.

[0059] Furthermore, such as Figure 7 As shown, the outer casing 121 includes an outer casing body 1211, an upper connector 1212, and a lower connector 1213. The upper connector 1212 and the lower connector 1213 are connected to the two ends of the outer casing body 1211. The mounting groove 127 is formed by the upper connector 1212 and the inner sliding sleeve 122, and the clearance groove 128 is formed by the lower connector 1213 and the inner sliding sleeve 122. Its structure is simple and compact, and it is convenient to disassemble and install.

[0060] In this embodiment, the first soluble protective sleeve 124 and the second soluble protective sleeve 125 are made of biodegradable polymer materials such as polyglycolic acid and polylactic acid to prevent cement slurry from entering the fracturing assembly 12 during cementing operations. Furthermore, sealing rings 129 are provided between the outer sleeve 1211 and the inner sliding sleeve 122, between the outer sleeve 1211 and the upper connector 1212, and between the outer sleeve 1211 and the lower connector 1213 to further prevent fluid from entering the fracturing assembly 12; the number of sealing rings 129 can be selected according to actual needs.

[0061] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A downhole fracturing tool, characterized in that, The device includes an outer tube, a soluble ball seat, and a setting component for inserting the soluble ball seat into the outer tube. The soluble ball seat includes a ball seat body and a pre-installed compression ball within the ball seat body. The ball seat body has a limiting part that engages with the outer tube for positioning, and an elastic component that drives the limiting part to extend and retract radially. When the soluble ball seat is inserted, the elastic component contracts and connects to the setting component, with the outer diameter of the limiting part being smaller than the inner diameter of the outer tube. When the soluble ball seat needs to be seated, the elastic component disengages from the setting component and expands radially outward, with the outer diameter of the limiting part being larger than the inner diameter of the outer tube. The outer tube includes... The casing body and the fracturing fitting components connected to the casing body include an outer sleeve, an inner sliding sleeve, a sliding sleeve shear pin, a first soluble protective sleeve, and a second soluble protective sleeve. The outer sleeve has a fracturing hole. The inner sliding sleeve is installed at the fracturing hole position by the sliding sleeve shear pin. The inner sliding sleeve moves downward when the sliding sleeve shear pin is cut to open the fracturing hole. The first and second soluble protective sleeves are respectively limited and installed at both ends of the inner sliding sleeve and degrade after cementing operations to form a mounting groove that fits with the limiting part and an avoidance groove that provides space for the inner sliding sleeve to move downward.

2. The downhole fracturing tool according to claim 1, characterized in that, The outer cover includes an outer cover body, an upper connector, and a lower connector. The upper connector and the lower connector are connected to both ends of the outer cover body. The seat hanging groove is formed by the upper connector and the inner sliding sleeve, and the clearance groove is formed by the lower connector and the inner sliding sleeve.

3. The downhole fracturing tool according to claim 1, characterized in that, The outer sleeve includes at least two separate sections, with a fitting gap between adjacent sections to accommodate the limiting part, and adjacent sections are connected by a coupling.

4. The downhole fracturing tool according to claim 3, characterized in that, The end of the setting component away from the soluble ball seat is connected to a perforating gun for perforating the outer tube, and the perforating gun is connected to a cable for pumping the soluble ball seat.

5. The downhole fracturing tool according to any one of claims 1 to 4, characterized in that, The elastic component includes a plurality of elastic ribs; the plurality of elastic ribs are arranged at circumferential intervals along the soluble ball seat to allow for contraction space when the elastic component is connected to the seated component.

6. The downhole fracturing tool according to claim 5, characterized in that, A positioning element is provided between the elastic rib and the seat sealing component. The positioning element is located on the side of the limiting part closer to the seat sealing component. The positioning element is cut off when the soluble ball seat needs to be seated.

7. The downhole fracturing tool according to claim 6, characterized in that, The seat sealing component includes an outer positioning sleeve and an inner positioning shaft that are sleeved together. The positioning element is located between the outer positioning sleeve and the elastic rib. The elastic rib abuts against the end face of the inner positioning shaft.

8. The downhole fracturing tool according to any one of claims 1 to 3, characterized in that, The lower end of the ball seat is provided with a rubber cup for sealing the annular space between the soluble ball seat and the outer tube.

9. The downhole fracturing tool according to any one of claims 1 to 3, characterized in that, There are at least two soluble ball seats, which are arranged at intervals along the axial direction of the outer sleeve; the inner side of the lower end of the ball seat body is provided with a plurality of return grooves for the return liquid after fracturing, which are arranged at intervals along the circumference of the ball seat body.

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