A pulse fracturing device

Abstract

This application discloses a pulse fracturing device, including a shell, an outer sleeve inside the shell, and a pressure relief chamber formed between the outer sleeve and the shell; a pressure-increasing hole is formed on the front end face of the outer sleeve; an inner sleeve is provided inside the outer sleeve, with a stepped surface formed by a narrowing in the middle of the inner sleeve, and a piston is fitted on the narrowed part of the inner sleeve, with a torsion spring between the piston and the stepped surface of the inner sleeve; multiple sleeve inclined bosses and multiple piston inclined bosses are respectively provided on the opposite surfaces of the inner sleeve and the piston; a fitting is also fitted on the narrowed neck of the inner sleeve, and a pressure-increasing chamber is formed between the fitting, the piston, and the inner sleeve, with the pressure-increasing chamber intermittently connected to the pressure-increasing hole and the pressure relief chamber; both the outer sleeve and the inner sleeve have intercepting grooves at their rear ends, and the intercepting grooves of the two are intermittently connected. This invention's device can repeatedly and continuously change the flow cross-sectional area of ​​the fracturing fluid in the perforation orifice, realizing pulse fracturing, improving the ability to generate rock fractures and the permeability of the rock fractures, thereby improving the production capacity of low-permeability oil and gas wells.

Description

Technical Field

[0001] This application relates to the field of oil well extraction equipment technology, and in particular to a pulse fracturing device. Background Technology

[0002] Fracturing technology is widely used in various types of oil wells. The process involves using a fracturing truck to inject high-pressure, high-volume, viscous fluid into the oil-bearing reservoir to fracture the geological structure and increase well production. Currently, hydraulic fracturing is the most common fracturing technology. It utilizes hydraulic force to create fractures in the oil reservoir, also known as hydraulic fracturing. While hydraulic fracturing can achieve oil recovery to some extent, it is often ineffective in increasing rock fractures and extending fracture distances in low-permeability reservoirs. Its ability to create fractures is weak, and it cannot sustain cyclical pressure application, resulting in low permeability of the fractured rock. This further leads to low production capacity and increased extraction costs in low-permeability oil wells. Summary of the Invention

[0003] To address the problem of low well productivity caused by weak fracturing capacity and low permeability of fractured rock, this application provides a pulse fracturing device that can effectively improve the ability to generate rock fractures and the permeability of the fractures, thereby improving the productivity of low-permeability oil wells.

[0004] The present invention is achieved by the following technical solution.

[0005] A pulse fracturing device includes a shell, an outer sleeve inside the shell, a pressure relief chamber formed between the outer sleeve and the shell, and the pressure relief chamber communicating with the outside; an axially extending pressure-pressuring hole is formed on the front end face of the outer sleeve; an inner sleeve is provided inside the outer sleeve, and a stepped central hole is provided in the inner sleeve; the middle diameter of the inner sleeve forms a stepped surface, and a piston is fitted on the reduced diameter part of the inner sleeve, with a torsion spring between the piston and the stepped surface of the inner sleeve; multiple sleeve inclined bosses and multiple piston inclined bosses are respectively provided on the opposite surfaces of the inner sleeve and the piston; an assembly is also fitted on the neck of the inner sleeve, the assembly is located on the side of the piston away from the piston inclined boss, and a pressure-pressuring chamber is formed between the assembly, the piston, and the inner sleeve, and the pressure-pressuring chamber is intermittently connected with the pressure-pressuring hole and the pressure relief chamber; both the outer sleeve and the inner sleeve have a flow-cutting groove at their rear ends, and the flow-cutting grooves of the two are intermittently connected, with the flow-cutting groove of the outer sleeve communicating with the outside.

[0006] By adopting the above technical solution, when the pulse fracturing device is working, the fracturing fluid enters the pressure chamber through the pressure hole of the outer sleeve. The liquid pressure in the pressure chamber causes the piston to move axially upward along the slide groove. When the end face of the piston inclined boss and the sleeve inclined boss come into contact, the sleeve body and the torsion spring rotate at a 45° angle due to further compression between them. During this process, the torsion spring stores compression and torsional potential energy. The pressure hole and the front connecting hole on the pressure chamber are misaligned, and the channel for the fracturing fluid to enter the pressure chamber is closed. The pressure relief inner hole and the rear connecting hole are connected, and the overflow channel of the fracturing fluid is opened. The fracturing fluid in the pressure chamber enters the pressure relief chamber through the pressure relief inner hole and the rear connecting hole, and then sprays out of the fracturing device, thereby relieving the pressure in the pressure chamber. After the pressure is released, the compression and torsional potential energy of the torsion spring is released, and the inner sleeve rotates 45° in the opposite direction to the torsion spring, returning to the initial state. The pressure hole on the outer sleeve reconnects with the front connecting hole, and the channel for fracturing fluid to enter the pressure chamber is reopened. The pressure relief inner hole and the rear connecting hole are misaligned, and the overflow channel of fracturing fluid is closed again, realizing the reciprocating rotation of the inner sleeve.

[0007] Furthermore, an inner pressure relief hole and an outer pressure relief hole are formed on the wall of the pressure relief chamber. The inner pressure relief hole is located on the bottom wall of the groove on the outer wall of the outer sleeve; the outer pressure relief hole is located on the shell.

[0008] Furthermore, the arrangement direction of the multiple sleeve bevel bosses on the inner sleeve is opposite to the arrangement direction of the multiple piston bevel bosses on the piston.

[0009] Furthermore, the device is equipped with a front connecting hole and a rear connecting hole, the front connecting hole being intermittently connected to the pressure punching hole, and the rear connecting hole being intermittently connected to the pressure relief inner hole.

[0010] Furthermore, the rear connecting hole and the pressure relief inner hole are offset in the circumferential direction.

[0011] Furthermore, the flow interception grooves of the outer sleeve and the inner sleeve are offset in the circumferential direction.

[0012] Furthermore, sealing rings are provided between the housing and the outer sleeve, as well as between the outer sleeve and the inner sleeve.

[0013] Furthermore, the outer wall of the piston is provided with a plurality of sliders circumferentially, and the extension direction of the sliders is parallel to the axial direction of the piston; the inner wall of the outer sleeve is provided with a groove for the sliders to be inserted.

[0014] Furthermore, both ends of the inner sleeve are fixed inside the outer sleeve by bearings.

[0015] Furthermore, the inner sleeve is also provided with an end cap at its front end.

[0016] This application has the following beneficial effects.

[0017] The fracturing device of this invention has a simple structure and is easy to install. By continuously changing the flow cross-sectional area of ​​the fracturing fluid in the perforation hole through the reciprocating rotation of the inner sleeve, pulse fracturing is achieved, which improves the ability to generate rock fractures and the permeability of rock fractures, thereby improving the production capacity of low-permeability oil and gas wells. It is highly practical. Attached Figure Description

[0018] Figure 1 This is a cross-sectional structural schematic diagram of the present invention;

[0019] Figure 2 This is a schematic diagram of the piston structure of the present invention;

[0020] Figure 3 A schematic diagram of the inner sleeve of this invention;

[0021] Figure 4 This is a schematic diagram of the outer sleeve of the present invention.

[0022] The components are as follows: 1. Shell, 2. Outer sleeve, 3. Inner sleeve, 4. Sealing ring, 5. Piston, 6. Torsion spring, 7. Bearing, 8. End cap, 9. Pressure hole, 10. Flow groove, 11. Pressure relief chamber, 12. Pressure relief inner hole, 13. Slider, 14. Piston inclined boss, 15. Set screw, 16. Assembly kit, 17. Sleeve inclined boss, 18. Front connecting hole, 19. Rear connecting hole, 20. Pressure hole, 21. Pressure relief outer hole, 22. Flow passage hole. Detailed Implementation

[0023] The present patent application will be further described below with reference to the accompanying drawings and embodiments.

[0024] like Figure 1-4 As shown, a pulse fracturing device includes a shell 1, an outer sleeve 2, an inner sleeve 3, a piston 5, a torsion spring 6, and a fitting 16.

[0025] The housing 1 contains an outer sleeve 2. The central hole of the housing 1 is a stepped hole. The outer sleeve 2 is axially positioned within the housing 1 through the stepped shoulder of the stepped hole. The outer sleeve 2 is fixed to the housing 1 by set screws 15 to achieve circumferential positioning. Sealing rings 4 are provided between the front and rear ends of the outer sleeve 2 and the housing 1. The outer wall of the outer sleeve 2 between the two sealing rings 4 is recessed inward to form a pressure relief chamber 11 with the housing 1. The pressure relief chamber 11 has an inner pressure relief hole 12 and an outer pressure relief hole 21. The inner pressure relief hole 12 is located on the bottom wall of the groove on the outer wall of the outer sleeve 2, and the outer pressure relief hole 21 is located on the housing 1. The inner pressure relief hole 12 and the outer pressure relief hole 21 allow fracturing fluid to enter the pressure relief chamber 11 through the inner pressure relief hole 12 and flow out of the pressure relief chamber 11 through the outer pressure relief hole 21 to the outside of the fracturing device of this application, thereby achieving the purpose of pressure relief. An inner sleeve 3 is installed inside the outer sleeve 2 via an end cap 8 and symmetrically arranged bearings 7. The end cap 8 is provided to facilitate the assembly of the inner sleeve 3. A sealing ring 4 is provided between the inner sleeve 3 and the outer sleeve 2.

[0026] The inner sleeve 3 has a stepped central hole, with the outlet end of the inner sleeve 3 being the smaller diameter end of the central hole. This allows for pressure changes at the outlet end of the central hole, creating a pressure buildup. The outer wall of the inner sleeve 3 has a narrowed middle section forming a stepped surface. A piston 5 is fitted onto the narrowed neck of the inner sleeve 3. A torsion spring 6 is positioned between the piston 5 and the stepped surface of the inner sleeve 3. One end of the torsion spring 6 is fixedly connected to the piston 5, and the other end is fixedly connected to the inner sleeve 3. Multiple sleeve inclined bosses 17 are evenly distributed on the circumference of the stepped surface of the inner sleeve 3. Multiple piston inclined bosses 14 are evenly distributed on the circumferential end face of the piston 5, corresponding to the end face of the inner sleeve 3. There are eight sleeve inclined bosses 17 and eight piston inclined bosses 14, each distributed at a 45° angle on the corresponding circumference of the inner sleeve 3 and piston 5. The end face of the inner sleeve 3 and the end face of the piston 5 are connected by a torsional contact through the engagement of the inclined boss 17 of the sleeve and the inclined boss 14 of the piston. Each inclined boss 17 of the sleeve and the corresponding inclined boss 14 of the piston face face opposite to each other, thereby enabling the inner sleeve 3 to rotate relative to each other under the action of external force.

[0027] The inner sleeve 3 and the outer sleeve 2 are respectively provided with intercepting grooves 10 on the lower circumference to facilitate the diversion of fracturing fluid. In the non-working state, the intercepting grooves 10 on the inner sleeve 3 and the intercepting grooves 10 on the outer sleeve 2 are misaligned in the circumferential direction, and the intercepting grooves 10 on the outer sleeve 2 are always connected to the flow holes 22 on the shell 1.

[0028] The piston 5 has sliders 13 spaced axially on its outer circumference. The inner wall of the outer sleeve 2 corresponding to the sliders 13 is provided with a sliding groove. The piston 5 and the outer sleeve 2 are slidably connected by the cooperation of the sliders 13 and the sliding groove, so that the piston 5 can only move axially and cannot rotate circumferentially.

[0029] The piston 5 is provided with a mounting bracket 16 on the inner sleeve 3 on the side away from the piston inclined boss 14. The mounting bracket 16 is fixedly connected to the inner sleeve 3. One end of the piston 5 is intermittently in contact with the mounting bracket 16, and the other end of the piston 5 is intermittently in contact with the end face of the inner sleeve 3.

[0030] A pressure chamber 20 is provided between the fitting 16 and the piston 5 and the inner sleeve 3. The pressure chamber 20 is provided with a front connecting hole 18 and a rear connecting hole 19. Both the front connecting hole 18 and the rear connecting hole 19 are provided on the fitting 16 corresponding to the pressure chamber 20 (see the instruction manual appendix). Figure 1 and 3 The outer sleeve 2 has an axially arranged pressure hole 9, which is intermittently connected to the front connecting hole 18. The pressure chamber 20 is connected to the rear connecting hole 19, the pressure relief inner hole 12, and the pressure relief chamber 11. The pressure relief inner hole 12 and the rear connecting hole 19 are offset at 45° in the circumferential direction. The liquid pressure generated by the accumulation of fracturing fluid in the pressure chamber 20 causes the piston 5 to contact and squeeze the flange end face of the inner sleeve 3, thereby causing the inner sleeve 3 to rotate torsionally.

[0031] When the pulse fracturing device is working, part of the fracturing fluid entering the device enters the central hole and flows out from the other end of the central hole. The other part of the fracturing fluid enters the pressure chamber 20 through the pressure hole 9 and the front connecting hole 18. The fracturing fluid entering the pressure chamber 20 acts on the end face of the piston 5, thereby pushing the piston 5 downward. During this process, the piston 5 compresses the torsion spring 6 to store its compression energy. When the piston inclined boss 14 on the piston 5 contacts the sleeve inclined boss 17, under the pressure of the fracturing fluid, the sleeve inclined boss 17 and the piston inclined boss 14 slide (rotate) relative to each other in the circumferential direction. The horizontal end faces of each sleeve inclined boss 17 and the horizontal end faces of the adjacent piston inclined boss 14 are in contact. The highest and lowest points of each piston inclined boss 14 are in contact with the lowest and highest points of the corresponding sleeve inclined boss 17, respectively. Then, the horizontal end faces of each sleeve inclined boss 17 and the horizontal end faces of the adjacent piston inclined boss 14 slide relative to each other, with the highest point of each piston inclined boss 14 sliding towards its lowest point. The horizontal end faces of each sleeve inclined boss 17 and the horizontal end faces of the corresponding piston inclined boss 14 are in contact. The highest and lowest points of each piston inclined boss 14 are in contact with the lowest and highest points of the adjacent sleeve inclined boss 17, respectively. This further enables the inner sleeve 3 to rotate 45°. Thus, the sleeve inclined boss 17 drives the inner sleeve 3 to rotate circumferentially. During the circumferential rotation of the inner sleeve 3, the torsion spring 6 is torsionally rotated, storing torsional energy. Simultaneously, during the circumferential rotation of the inner sleeve 3, the pressure-pressuring hole 9 and the front connecting hole 18 on the pressure-pressuring chamber 20 gradually close, while the pressure-relieving inner hole 12 on the pressure-relieving chamber 11 and the rear connecting hole 19 gradually open. When the inclined boss 17 of the sleeve and the inclined boss 14 of the piston slide to the stop point, the pressure-pressuring hole 9 and the front connecting hole 18 on the pressure-pressuring chamber 20 are completely closed, and the pressure-relieving inner hole 12 on the pressure-relieving chamber 11 and the rear connecting hole 19 are completely opened. At this time, the fracturing fluid in the pressure-pressuring chamber 20 is discharged into the annulus between the fracturing device and the wellbore through the rear connecting hole 19, the pressure-relieving inner hole 12, the pressure-relieving chamber 11, and the pressure-relieving outer hole 21, thereby achieving pressure relief.

[0032] After the fracturing fluid in the pressure chamber 20 is depressurized, the piston 5 returns to its original position under the action of the compression energy stored in the torsion spring 6, and the inner sleeve 3 rotates in the opposite direction to return to its original position under the action of the torsional energy stored in the torsion spring 6. At this time, the pressure relief inner hole 12 and the rear connecting hole 19 on the pressure relief chamber 11 gradually close, and the pressure relief hole 9 and the front connecting hole 18 on the pressure relief chamber 20 gradually open. When the pressure relief inner hole 12 and the rear connecting hole 19 on the pressure relief chamber 11 are completely closed, and the pressure relief hole 9 and the front connecting hole 18 on the pressure relief chamber 20 are completely open, the next working cycle can begin.

[0033] The pulse fracturing device of this application has a stepped orifice at its center and a small-diameter outlet. During operation, the fracturing fluid entering the center orifice forms a pressure build-up at the outlet. The piston bevel boss 14 on piston 5 and the sleeve bevel boss 17 make contact, causing the inner sleeve 3 to rotate. As the inner sleeve 3 rotates, the intercepting groove 10 on the inner sleeve 3 and the intercepting groove 10 on the outer sleeve 2 gradually come into contact. When the inner sleeve 3 is fully rotated, the intercepting groove 10 on the inner sleeve 3 and the intercepting groove 10 on the outer sleeve 2 are completely connected. At this time, part of the fracturing fluid that forms a pressure build-up at the outlet of the center orifice is discharged through the intercepting groove 10 on the inner sleeve 3, the intercepting groove 10 on the outer sleeve 2, and the flow hole 22. The other part of the fracturing fluid continues to flow out from the outlet of the center orifice. Because part of the fracturing fluid that forms a pressure build-up at the outlet of the center orifice flows through the inner sleeve 3, the outer sleeve 2, and the flow hole 22, the fracturing fluid continues to flow out from the outlet of the center orifice. The flow channels 10 on the inner sleeve 3, the outer sleeve 2, and the flow holes 22 are discharged, thus reducing the area of ​​fracturing fluid flowing out from the outlet end and causing the fracturing fluid flowing out from the outlet end to generate pulses. Under the action of the torsion spring 6, the inner sleeve 3 gradually rotates in the reverse direction to reset, and the flow channels 10 on the inner sleeve 3 and the outer sleeve 2 gradually close. When the inner sleeve 3 rotates in the reverse direction to the position, the flow channels 10 on the inner sleeve 3 and the outer sleeve 2 are completely closed. At this time, the fracturing fluid flows out from the outlet end of the central hole, thus relatively increasing the area of ​​fracturing fluid flowing out from the outlet end and causing the fracturing fluid flowing out from the outlet end to generate pulses. The reciprocating torsional rotation of the inner sleeve 3 causes the area of ​​fracturing fluid at the outlet end of the central hole to change alternately, thereby achieving pulse fracturing and achieving the purpose of increasing the production of low-permeability oil and gas wells.

[0034] The pulse fracturing device of this application uses the reciprocating torsional rotation of the inner sleeve 3 to continuously change the flow cross-sectional area of ​​the fracturing fluid injected into the outlet end of the central hole, thereby realizing pulse fracturing, improving the ability to generate rock fractures and the permeability of rock fractures, and thus improving the production capacity of low-permeability oil and gas wells.

[0035] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A pulse-type fracturing device, characterized in that: Includes a housing (1), an outer sleeve (2) inside the housing (1), a pressure relief chamber (11) is formed between the outer sleeve (2) and the housing (1), and the pressure relief chamber (11) is connected to the outside; an axially extending pressure hole (9) is formed on the front end face of the outer sleeve (2); an inner sleeve (3) is provided inside the outer sleeve (2), and a stepped central hole is provided inside the inner sleeve (3). The middle part of the inner sleeve (3) is narrowed to form a stepped surface, and a piston (5) is fitted on the narrowed part of the inner sleeve (3). A torsion spring (6) is provided between the piston (5) and the stepped surface of the inner sleeve (3); on the opposite surfaces of the inner sleeve (3) and the piston (5) Multiple sleeve inclined bosses (17) and multiple piston inclined bosses (14) are provided respectively; the inner sleeve (3) is also fitted with a fitting (16) on the reduced diameter part, the fitting (16) is located on the side of the piston (5) away from the piston inclined boss (14), the fitting (16), the piston (5) and the inner sleeve (3) form a pressure chamber (20), the pressure chamber (20) is intermittently connected with the pressure hole (9) and the pressure relief chamber (11); the rear ends of the outer sleeve (2) and the inner sleeve (3) are both provided with intercepting grooves (10), the intercepting grooves (10) of the two are intermittently connected, and the intercepting groove (10) of the outer sleeve (2) is connected to the outside.

2. The pulse-type fracturing device according to claim 1, characterized in that: The pressure relief chamber (11) has an inner pressure relief hole (12) and an outer pressure relief hole (21) formed on its cavity wall. The inner pressure relief hole (12) is located on the bottom wall of the groove on the outer wall of the outer sleeve (2). The outer pressure relief hole (21) is located on the shell (1).

3. The pulse-type fracturing device according to claim 1, characterized in that: The arrangement direction of multiple sleeve inclined bosses (17) on the inner sleeve (3) is opposite to the arrangement direction of multiple piston inclined bosses (14) on the piston (5).

4. The pulse-type fracturing device according to claim 1, characterized in that: The assembly (16) is provided with a front connecting hole (18) and a rear connecting hole (19). The front connecting hole (18) is intermittently connected to the pressure hole (9), and the rear connecting hole (19) is intermittently connected to the pressure relief inner hole (12).

5. The pulse-type fracturing device according to claim 4, characterized in that: The rear connecting hole (19) and the pressure relief inner hole (12) are offset in the circumferential direction.

6. The pulse-type fracturing device according to claim 1, characterized in that: The intercepting groove (10) of the outer sleeve (2) and the intercepting groove (10) of the inner sleeve (3) are offset in the circumferential direction.

7. The pulse-type fracturing device according to claim 1, characterized in that: A sealing ring (4) is provided between the shell (1) and the outer sleeve (2) and between the outer sleeve (2) and the inner sleeve (3).

8. The pulse fracturing device according to claim 1, characterized in that: The piston (5) has a plurality of sliders (13) circumferentially arranged on its outer wall, and the extension direction of the sliders (13) is parallel to the axial direction of the piston (5); the inner wall of the outer sleeve (2) is provided with a groove for the sliders (13) to be inserted.

9. A pulse-type fracturing device according to claim 1, characterized in that: The two ends of the inner sleeve (3) are fixed inside the outer sleeve (2) by bearings (7).

10. A pulse-type fracturing device according to claim 1, characterized in that: The inner sleeve (3) is also provided with an end cap (8) at its front end.

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