Device and method for controlling opening and closing of horizontal well fracturing string through self-telescopic spring plugging valve

Abstract

The invention provides a device and method for controlling opening and closing of a horizontal well fracturing pipe column through a self-telescopic spring plugging valve. The device comprises an upper connector, a lower connector, a blowout mechanism assembly, a circulation mechanism assembly and a reset mechanism assembly. The upper connector is connected with the blowout mechanism assembly, the blowout mechanism assembly is connected with the circulation mechanism assembly, and the circulation mechanism assembly is connected with the lower connector. The reset mechanism assembly is arranged in the circulation mechanism assembly and connected with the upper end face of the lower connector. A plurality of bypass valves are annularly arranged at the upper part of the blowout mechanism assembly; an upper bypass valve and a lower bypass valve are arranged on the lower middle portion of the circulation mechanism assembly, and an outer sleeve bypass valve is arranged in the middle of the circulation mechanism assembly. By means of the circulating mechanism assembly and the reset mechanism assembly which are arranged in the device and the hydraulic dual effect, unblocking or blocking in the oil pipe is achieved, the functions of blocking and unblocking in the oil pipe are achieved repeatedly through the device, and continuous fracturing of the horizontal well without pressure relief and layer changing is achieved.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas field drilling operation equipment, and in particular relates to a device and a method for controlling the switch of a horizontal well fracturing pipe column by a self-retractable spring plugging valve. Background Art

[0002] During the multi-layer fracturing of horizontal wells, when conventional tubing is used for fracturing, after fracturing one section, it is necessary to release the pressure by blowing, open the wellhead, and adjust the position of the fracturing tubing before fracturing the next section. The consequences are: first, the work delay due to blowing is long, accounting for 41% of the total well construction time; second, the return fluid is difficult to recover and treat, polluting the environment; third, the underground fracturing fluid is released prematurely, reducing the effectiveness of the measures.

[0003] Publication number CN102134977A discloses a temporary plugging device for a well column that is prone to blowout and leakage. The invention relates to a temporary plugging device for a well column that is prone to blowout and leakage, and is also a control device for the closure pressure of a hydraulically set packer. Specifically, it relates to a downhole plugging valve, including a pump-out plugging valve and a secondary plugger; the pump-out plugging valve includes an upper joint, a lower joint, a valve plug, a shear pin and a sealing ring connected in sequence, and the secondary plugger includes an upper mandrel, a slip, a spring, a sealing ring and a lower mandrel connected in sequence, and the secondary plugging valve is arranged in the pump-out plugging valve. The secondary plugging valve is easy to operate and has a good plugging effect, and at the same time ensures that the maximum inner diameter of the pipe column is convenient for the ball seat of the set packer to replace the tool.

[0004] Therefore, it is urgent to optimize the horizontal well fracturing string and use conventional well repair power to achieve continuous fracturing of horizontal wells without pressure relief and layer change. Summary of the invention

[0005] In order to overcome the problems of long delay in work during existing blowout, great difficulty in recovering and treating the backflow fluid, and early release of the underground fracturing fluid reducing the effectiveness of the measures, the present invention provides a device and method for controlling the switch of the horizontal well fracturing string by a self-retractable spring plugging valve. In the initial state of the present invention, the oil pipe is unobstructed to achieve reverse circulation well washing; after well washing, the oil pipe is unobstructed by relying on the built-in circulation mechanism assembly and reset mechanism assembly structure and hydraulic dual effects of the device, and fracturing construction is carried out; when changing layers, the oil pipe is blocked by relying on the built-in circulation mechanism assembly and reset mechanism assembly structure and hydraulic dual effects of the device, and the existing annular blowout preventer is used to block the oil casing annulus, and the position of the fracturing string is adjusted under pressure without blowout; the function of repeatedly blocking and unobstructing the oil pipe is used to achieve continuous fracturing of horizontal wells without pressure relief and layer change. In case of emergencies, the blowout sliding sleeve pre-set in the device can be used to achieve blowout in the oil pipe and reverse circulation well washing.

[0006] The technical solution adopted by the present invention is: A device for controlling the switch of a horizontal well fracturing pipe column by a self-retractable spring sealing valve comprises an upper joint, a lower joint, a blowout mechanism assembly, a circulation mechanism assembly and a reset mechanism assembly; the upper joint is connected to the blowout mechanism assembly, the blowout mechanism assembly is connected to the circulation mechanism assembly, and the circulation mechanism assembly is connected to the lower joint; the reset mechanism assembly is arranged in the circulation mechanism assembly and connected to the upper end surface of the lower joint; a plurality of bypass valves are arranged in a ring on the upper part of the blowout mechanism assembly; an upper bypass valve and a lower bypass valve are arranged in the middle and lower part of the circulation mechanism assembly, and a jacket bypass valve is arranged in the middle part of the circulation mechanism assembly.

[0007] The spray mechanism assembly includes a spray outer cylinder, a positioning sleeve, a shear pin and a spray sliding sleeve. The upper part of the spray outer cylinder is connected to the upper joint, and the lower part is connected to the outer cylinder. The positioning sleeve is fixed to the spray sliding sleeve by a shear pin. A spray sliding sleeve steel ball is provided on the upper end surface of the spray sliding sleeve. The spray sliding sleeve steel ball seat is on the upper end surface of the spray sliding sleeve and seals the spray sliding sleeve. A plurality of bypass valves are arranged in a ring on the spray outer cylinder.

[0008] The upper part of the spray-discharging outer cylinder is threadedly connected with the upper joint, and the lower part is threadedly connected with the outer cylinder.

[0009] The circulation mechanism assembly comprises an outer cylinder, a sealing core shaft, an outer sleeve, a shear pin and a sealing sleeve. The upper end of the outer cylinder is connected to the spraying outer cylinder of the spraying mechanism assembly, and the lower end of the outer cylinder is connected to the lower joint; the annulus between the lower part of the outer cylinder and the outer sleeve is hollow, and is connected to the inner cavity of the lower joint to form a liquid flow channel; the sealing core shaft is located at the upper end part of the inner cavity of the outer sleeve, the upper vertex of the sealing core shaft is the outer sleeve limit groove, and the lower end of the sealing core shaft is connected to the reset mechanism assembly; an upper bypass valve and a lower bypass valve are arranged at the lower part of the sealing core shaft; the sealing sleeve is located in the middle and lower part of the inner cavity of the sealing core shaft, and is fixed to the inner cavity wall of the sealing core shaft by a shear pin 2; a sealing sleeve steel ball is arranged on the upper end surface of the sealing sleeve, and the sealing sleeve steel ball seat is seated on the upper end surface of the sealing sleeve and seals the sealing sleeve.

[0010] In the initial state of the circulation mechanism assembly, the lower bypass valve on the sealing core shaft overlaps with the outer sleeve bypass valve set on the outer sleeve to form a liquid flow channel; the sealing sleeve steel ball seats on the upper end surface of the sealing sleeve and seals the sealing sleeve; after the sealing sleeve steel ball is under pressure, the shear pin 2 is cut off, the sealing sleeve falls off, and the lower bypass valve on the sealing core shaft is sealed.

[0011] The upper end of the outer cylinder is threadedly connected to the spraying outer cylinder, and the lower end is threadedly connected to the lower joint.

[0012] The reset mechanism assembly includes a sealing plug, a spring and a pressure transmission plug; the upper part of the sealing plug is connected to the sealing core shaft of the circulation mechanism assembly, and the lower part of the sealing plug is connected to the spring; the upper end of the pressure transmission plug is connected to the spring, and the lower end is fixed to the upper end surface of the inner cavity of the lower joint.

[0013] A gasket is arranged between the pressure transmission plug and the upper end surface of the inner cavity of the lower joint.

[0014] The spring comprises an outer spring and an inner spring, wherein the inner spring is arranged inside the outer spring.

[0015] A method for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve, the specific steps are as follows: Step 1: lower a fracturing string into the well, connect the upper end of the fracturing string to the wellhead, install an annular blowout preventer at the wellhead, and seal the wellhead; Step 2: In the initial state, the lower bypass valve and the outer casing bypass valve overlap, and the inner cavity of the fracturing string is in a smooth state; Step 3: Put the sealing sleeve steel ball into the oil pipe, pressurize the oil pipe to at least 10MPa, cut the shear pin 2, knock out the sealing sleeve, and close the lower bypass valve. At this time, the fracturing string is in a plugged state; Step 4: Continue to pressurize to 25-30MPa, and hydraulically push the sealing mandrel compression spring downward. When the upper bypass valve and the outer jacket bypass valve are completely overlapped, the inner cavity of the fracturing string is in a smooth state; Step 5, performing fracturing construction according to the fracturing pumping procedure; Step 6: After the fracturing is completed, the oil pipe is discharged with a small displacement, the spring pushes the sealing core shaft upward, the upper bypass valve and the outer jacket bypass valve are staggered and closed, so that the inner cavity of the fracturing string is in a closed state, and the inner sealing of the oil pipe is achieved; Step 7: close the annular blowout preventer, unload the wellhead, drag the fracturing string under pressure, adjust the position of the fracturing string, and perform layer-changing fracturing; Step 8, repeating steps 4 to 7 until all well sections are fractured; Step nine, when an emergency occurs, put the blowout sleeve steel ball into the oil pipe, pressurize the oil pipe to 15MPa, cut the shear pin one, knock out the blowout sleeve, open the blowout outer tube bypass valve, thereby forming an oil casing annulus circulation channel to achieve positive and reverse circulation well washing.

[0016] Beneficial effects of the present invention: The present invention provides a device for controlling the switch of the horizontal well fracturing string with a self-retractable spring plugging valve. In the initial state, the oil pipe is unobstructed, realizing reverse circulation well washing; in the initial state of the present invention, the lower bypass valve overlaps with the outer bypass valve, and the inner cavity of the fracturing string is in an unobstructed state, realizing reverse circulation oil replacement and degassing. A sealing sleeve steel ball is inserted into the oil pipe, and the oil pipe is pressurized to 10MPa, the shear pin 2 is cut off, the sealing sleeve is knocked off, and the lower bypass valve is closed. At this time, the fracturing string is in a blocked state; the pressure is continued to be raised to 25-30MPa, and the sealing core shaft compression spring is hydraulically pushed downward. When the upper bypass valve and the outer bypass valve are completely overlapped, the inner cavity of the fracturing string is in an unobstructed state. At this time, under the action of the hydraulic pressure, the packer in the fracturing string is also in a seated state. Fracturing construction is carried out according to the fracturing pumping procedure. After fracturing is completed, the oil pipe is released with a small displacement, the spring pushes the sealing core shaft upward, the upper bypass valve and the outer jacket bypass valve are staggered and closed, so that the inner cavity of the fracturing pipe string is in a closed state, realizing the sealing inside the oil pipe.

[0017] After well washing, the present invention relies on the built-in circulation mechanism assembly and reset mechanism assembly structure and hydraulic dual effects of the device to achieve unblocked oil pipes and perform fracturing construction; when changing layers, the device relies on the built-in circulation mechanism assembly and reset mechanism assembly structure and hydraulic dual effects to achieve plugging in the oil pipes, and uses the existing annular blowout preventer to achieve oil casing annulus plugging, without the need for blowout, and adjusts the position of the fracturing string under pressure; the device repeatedly achieves the function of plugging and unblocking in the oil pipe, and realizes continuous fracturing of horizontal wells without pressure relief and layer change. In case of emergencies, the device uses the preset blowout sliding sleeve to achieve blowout in the oil pipe and reverse circulation well washing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below with reference to the accompanying drawings.

[0019] Figure 1 Schematic diagram of the self-retractable spring blocking valve structure.

[0020] Figure 2 Schematic diagram of the sealing core shaft structure.

[0021] Figure 3 Schematic diagram of the jacket structure.

[0022] Figure 4 Schematic diagram of the spray outer cylinder structure.

[0023] In the figure, the reference numerals are: 1. Upper joint; 2. Blowout outer cylinder; 3. Positioning sleeve; 4. Shear pin 1; 5. Blowout sleeve; 6. Outer cylinder; 7. Sealing mandrel; 8. Outer sleeve; 9. Sealing sleeve; 10. Sealing plug; 11. Outer spring; 12. Inner spring; 13. Gasket; 14. Lower joint; 15. Pressure transmission plug; 16. O-ring 1; 17. O-ring 2; 18. O-ring 3; 19. O-ring 4; 20. Blowout sleeve steel ball; 21. Sealing sleeve steel ball; 22. Upper bypass valve; 23. Lower bypass valve; 24. Outer sleeve bypass valve; 25. Bypass valve; 26. Shear pin 2. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0026] Embodiment 1: In order to overcome the problems of long work delays during conventional blowdown, great difficulty in recovering and treating the flowback fluid, and reduced effectiveness of measures due to premature release of the underground fracturing fluid, the present invention provides a method as follows: Figure 1-4 The device and method for controlling the switch of the horizontal well fracturing string by a self-retractable spring plugging valve shown in the figure, in the initial state of the present invention, the oil pipe is unobstructed, and reverse circulation well washing is realized; after well washing, the oil pipe is unobstructed by relying on the built-in circulation mechanism assembly and reset mechanism assembly structure and the dual action of hydraulic pressure of the device, and fracturing construction is carried out; when changing layers, the oil pipe is blocked by relying on the built-in circulation mechanism assembly and reset mechanism assembly structure and the dual action of hydraulic pressure of the device, and the existing annular blowout preventer is used to block the oil casing annulus, and the position of the fracturing string is adjusted under pressure without releasing the blowout; the function of repeatedly blocking and unobstructing the oil pipe is used to realize continuous fracturing of horizontal wells without pressure relief and layer changing. In case of emergencies, the blowout sliding sleeve pre-installed in the device can be used to realize blowout in the oil pipe and reverse circulation well washing.

[0027] A device for controlling the switch of a horizontal well fracturing pipe string with a self-retractable spring sealing valve comprises an upper joint 1, a lower joint 14, a blowout mechanism assembly, a circulation mechanism assembly and a reset mechanism assembly; the upper joint 1 is connected to the blowout mechanism assembly, the blowout mechanism assembly is connected to the circulation mechanism assembly, and the circulation mechanism assembly is connected to the lower joint 14; the reset mechanism assembly is arranged in the circulation mechanism assembly and is connected to the upper end surface of the lower joint 14; a plurality of bypass valves 25 are arranged in a ring on the upper part of the blowout mechanism assembly; an upper bypass valve 22 and a lower bypass valve 23 are arranged in the middle and lower part of the circulation mechanism assembly, and a jacket bypass valve 24 is arranged in the middle part of the circulation mechanism assembly.

[0028] like Figure 1 As shown, the self-retractable spring plugging valve at least includes an upper joint 1, a lower joint 14, a blowout mechanism assembly, a circulation mechanism assembly and a reset mechanism assembly. In the present invention, the upper joint 1 is connected to the tool tubing or the lower joint of the downhole tool to form a whole, and its interior forms a liquid flow channel with the interior of the fracturing string; the lower joint 14 is connected to the tool tubing or the upper joint of the downhole tool to form a whole, and its interior forms a liquid flow channel with the interior of the fracturing string.

[0029] Embodiment 2: Based on Example 1, in this embodiment, preferably, the spray mechanism assembly includes a spray outer cylinder 2, a positioning sleeve 3, a shear pin 4 and a spray sliding sleeve 5, the upper part of the spray outer cylinder 2 is connected to the upper joint 1, and the lower part is connected to the outer cylinder 6, the positioning sleeve 3 is fixed to the spray sliding sleeve 5 by the shear pin 4; a spray sliding sleeve steel ball 20 is provided on the upper end surface of the spray sliding sleeve 5, the spray sliding sleeve steel ball 20 is seated on the upper end surface of the spray sliding sleeve 5 and seals the spray sliding sleeve 5; a plurality of bypass valves 25 are arranged in a ring on the spray outer cylinder 2.

[0030] Preferably, the upper portion of the spray-release outer cylinder 2 is threadedly connected to the upper joint 1 , and the lower portion is threadedly connected to the outer cylinder 6 .

[0031] like Figure 1 and Figure 4 As shown, the upper part of the spray outer tube 2 is threadedly connected to the upper joint 1, and the lower part is threadedly connected to the outer tube 6; the positioning sleeve 3 is fixed to the inner cavity of the spray outer tube 2 by means of a limiting groove, and the shear pin 14 is fixedly connected to the positioning sleeve 3 and the spray sliding sleeve 5; the spray sliding sleeve steel ball 20 is seated on the upper end surface of the spray sliding sleeve 5 to seal the spray sliding sleeve 5. After the spray sliding sleeve steel ball 20 is under pressure, the shear pin 14 is cut off, the spray sliding sleeve 5 falls off, and the six bypass valves 25 arranged in an annular manner on the spray outer tube are opened.

[0032] Preferably, the circulation mechanism assembly comprises an outer cylinder 6, a sealing core shaft 7, an outer sleeve 8, a shear pin 26 and a sealing sleeve 9, the upper end of the outer cylinder 6 is connected to the spraying outer cylinder 2 of the spraying mechanism assembly, and the lower end of the outer cylinder 6 is connected to the lower joint 14; the annulus between the lower part of the outer cylinder 6 and the outer sleeve 8 is hollow, and is connected to the inner cavity of the lower joint 14 to form a liquid flow channel; the sealing core shaft 7 is located at the upper end of the inner cavity of the outer sleeve 8, the upper vertex of the sealing core shaft 7 is the limiting groove of the outer sleeve 8, and the lower end of the sealing core shaft 7 is connected to the reset mechanism assembly; an upper bypass valve 22 and a lower bypass valve 23 are arranged at the lower part of the sealing core shaft 7; the sealing sleeve 9 is located in the middle and lower part of the inner cavity of the sealing core shaft 7, and is fixed to the inner cavity wall of the sealing core shaft 7 by the shear pin 26; a sealing sleeve steel ball 21 is provided on the upper end surface of the sealing sleeve 9, and the sealing sleeve steel ball 21 is seated on the upper end surface of the sealing sleeve 9 and seals the sealing sleeve 9.

[0033] Preferably, in the initial state of the circulation mechanism assembly, the lower bypass valve 23 on the sealing core shaft 7 overlaps with the outer sleeve bypass valve 24 provided on the outer sleeve 6 to form a liquid flow channel; the sealing sleeve steel ball 21 is seated on the upper end surface of the sealing sleeve 9 and seals the sealing sleeve 9; after the sealing sleeve steel ball 21 is under pressure, the shear pin 26 is cut off, the sealing sleeve 9 falls, and the lower bypass valve 23 on the sealing core shaft 7 is sealed.

[0034] Preferably, the upper end of the outer cylinder 6 is threadedly connected to the spray outer cylinder 2, and the lower end is threadedly connected to the lower joint 14.

[0035] In the present invention, Figure 1 , Figure 2 and Figure 3 As shown, the upper end of the outer tube 6 is threadedly connected to the spray outer tube 2, and the lower end is threadedly connected to the lower joint 14; Figure 3 As shown, the annulus between the outer tube 6 and the outer sleeve 8 below the outer sleeve bypass valve 24 is hollow and communicates with the inner cavity of the lower joint 14 to form a liquid flow channel; the sealing core shaft 7 is located at the upper end of the inner cavity of the outer sleeve 8 and can move up and down, the upper vertex is the limit groove of the outer sleeve 8, and the lower end is connected to the sealing plug 10; Figure 2 As shown, an upper bypass valve 22 and a lower bypass valve 23 are arranged at the lower part of the sealing core shaft 7. In the initial state, the lower bypass valve 23 overlaps with the outer sleeve bypass valve 24 to form a liquid flow channel; the sealing sleeve 9 is located in the lower middle part of the inner cavity of the sealing core shaft 7, and is fixed to the inner cavity wall of the sealing core shaft 7 by using a second shear pin 26; the sealing sleeve steel ball 21 is seated on the upper end surface of the sealing sleeve 9 to seal the sealing sleeve 9; after the sealing sleeve steel ball 21 is under pressure, the second shear pin 26 is cut off, the sealing sleeve 9 falls off, and the lower bypass valve 23 of the sealing core shaft is sealed.

[0036] Preferably, the reset mechanism assembly includes a sealing plug 10, a spring and a pressure transmitting plug 15; the upper part of the sealing plug 10 is connected to the sealing core shaft 7 of the circulation mechanism assembly, and the lower part of the sealing plug 10 is connected to the spring; the upper end of the pressure transmitting plug 15 is connected to the spring, and the lower end is fixed to the upper end surface of the inner cavity of the lower joint 14.

[0037] Preferably, a gasket 13 is provided between the pressure transmission plug 15 and the upper end surface of the inner cavity of the lower joint 14 .

[0038] Preferably, the spring comprises an outer spring 11 and an inner spring 12 , and the inner spring 12 is arranged inside the outer spring 11 .

[0039] In the present invention, the upper part of the sealing plug 10 is connected to the sealing core shaft 7, and the lower part is connected to the outer spring 11 and the inner spring 12, and a filter is arranged in the hollow part; the upper ends of the pressure transmission plug 15 and the gasket 13 are connected to the outer spring 11 and the inner spring 12, and the lower ends are fixed to the upper end surface of the inner cavity of the lower joint 14, and the gasket 13 protects the pressure transmission plug 15.

[0040] In the present invention, the upper joint and the spray outer cylinder 2 are sealed by an O-ring 16, and the outer cylinder 6 and the lower joint 14 are sealed by an O-ring 16. The O-ring 16 is arranged in the corresponding sealing groove. The spray outer cylinder 2 and the sealing core shaft 7 are sealed by an O-ring 2 17, and the O-ring 2 17 is arranged in the corresponding sealing groove. The spray outer cylinder 2 and the spray sliding sleeve 5 are sealed by an O-ring 3 18, and the O-ring 3 18 is arranged in the corresponding sealing groove. A sealing groove is provided on the outer wall of the sealing sliding sleeve 9, and an O-ring 19 is arranged in the sealing groove.

[0041] Before the fracturing construction of the present invention, in the initial state, the oil pipe is unobstructed, and reverse circulation well washing is realized; after well washing, the oil pipe is unobstructed by relying on the built-in structure of the binding paper and the dual effects of hydraulic pressure, and fracturing construction is carried out; when changing layers, the oil pipe is blocked by relying on the built-in structure of the device and the dual effects of hydraulic pressure, and the oil casing annulus is blocked by using the existing annular blowout preventer, and the position of the fracturing drill tool is adjusted under pressure without releasing the blowout; the function of repeatedly blocking and unobstructing the oil pipe is used to realize continuous fracturing of horizontal wells without pressure relief and layer changing. In case of emergencies, the blowout sliding sleeve pre-set in the device can be used to realize blowout in the oil pipe and reverse circulation well washing.

[0042] Embodiment 3: Based on Example 1 or 2, in this embodiment, a method for controlling the switch of a horizontal well fracturing string with a self-retractable spring plugging valve is provided, and the specific steps are as follows: Step 1: Lower the fracturing string into the well, connect the upper end of the fracturing string to the wellhead, install an annular blowout preventer at the wellhead, and seal the wellhead; the fracturing string includes: guide plug + Y211 packer + check valve + sandblaster + 1 tool tubing + throttle valve + self-retractable spring plugging valve (without steel ball) + K344 packer + hydraulic anchor + 1 tool tubing + safety joint + tool tubing to the wellhead, install an annular blowout preventer at the wellhead, and seal the wellhead with a Y211 packer.

[0043] Step 2: In the initial state, the lower bypass valve 23 and the outer jacket bypass valve 24 overlap, and the inner cavity of the fracturing string is in a smooth state; reverse circulation is achieved to replace oil and degas, which is conducive to the smooth seating of the K344 packer.

[0044] Step 3: insert the sealing sleeve steel ball 21 into the oil pipe, pressurize the oil pipe to at least 10 MPa, cut the shear pin 26, knock out the sealing sleeve 9, and close the lower bypass valve 23. At this time, the fracturing string is in a plugged state; Step 4, continue to pressurize to 25-30MPa, hydraulically push the sealing core shaft 7 to compress the spring downward, when the upper bypass valve 22 and the outer jacket bypass valve 24 are completely overlapped, the inner cavity of the fracturing string is in a smooth state; at this time, under the action of hydraulic pressure, the K344 packer is also in a seated state.

[0045] Step 5, performing fracturing construction according to the fracturing pumping procedure; Step 6: After the fracturing is completed, the oil pipe is released with a small displacement, the spring pushes the sealing core shaft 7 upward, the upper bypass valve 22 and the outer jacket bypass valve 24 are staggered and closed, so that the inner cavity of the fracturing pipe string is in a closed state, and the inner sealing of the oil pipe is achieved; Step 7: close the annular blowout preventer, unload the wellhead, drag the fracturing string under pressure, adjust the position of the fracturing string, and perform layer-changing fracturing; Step 8, repeating steps 4 to 7 until all well sections are fractured; Step nine, when an emergency occurs, put the blowout sliding sleeve steel ball 20 into the oil pipe, pressurize the oil pipe to 15MPa, cut the shear pin 4, knock out the blowout sliding sleeve 5, open the blowout outer tube bypass valve 25, thereby forming an oil casing annulus circulation channel to achieve positive and reverse circulation well washing.

[0046] After the device provided by the present invention is put into specific application, compared with the traditional fracturing process, the construction time for a single well is saved by 17.5 days, the flowback fluid is reduced by 4,500 cubic meters, the construction team's operating efficiency is improved by 38%, and the cost is saved by more than 490,000 yuan. The annual workload is expected to be 50 wells, and the economic benefits can reach 24.675 million yuan. In June 2022, the self-retractable spring plugging valve optimized the horizontal well fracturing string, and was tested in the Chuanping 50-25 and Chuanping 53-14 wells of the Oil Production Plant No. 10, realizing continuous fracturing without pressure relief and layer change, achieving the expected goal. So far, this technology has been promoted and applied in 15 wells of the Oil Production Plant No. 10 and Chuanqing Drilling. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0048] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. Any design that is the same or similar to the present invention belongs to the protection scope of the present invention. The device structures and method steps not described in detail in the present invention are all prior art and will not be further described in the present invention.

Claims

1. A device for controlling the switch of horizontal well fracturing string by a self-retractable spring plugging valve. Features: The invention comprises an upper joint (1), a lower joint (14), a spraying mechanism assembly, a circulation mechanism assembly and a reset mechanism assembly; the upper joint (1) is connected to the spraying mechanism assembly, the spraying mechanism assembly is connected to the circulation mechanism assembly, and the circulation mechanism assembly is connected to the lower joint (14); the reset mechanism assembly is arranged in the circulation mechanism assembly and is connected to the upper end surface of the lower joint (14); a plurality of bypass valves (25) are arranged in a ring at the upper part of the spraying mechanism assembly; an upper bypass valve (22) and a lower bypass valve (23) are arranged at the middle and lower part of the circulation mechanism assembly, and a jacket bypass valve (24) is arranged at the middle part of the circulation mechanism assembly.

2. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to claim 1, Features: The spray mechanism assembly comprises a spray outer cylinder (2), a positioning sleeve (3), a shear pin (4) and a spray sliding sleeve (5); the upper portion of the spray outer cylinder (2) is connected to an upper joint (1), and the lower portion is connected to an outer cylinder (6); the positioning sleeve (3) is fixed to the spray sliding sleeve (5) via a shear pin (4); a spray sliding sleeve steel ball (20) is provided on the upper end surface of the spray sliding sleeve (5); the spray sliding sleeve steel ball (20) is seated on the upper end surface of the spray sliding sleeve (5) and seals the spray sliding sleeve (5); a plurality of bypass valves (25) are arranged in an annular manner on the spray outer cylinder (2).

3. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to claim 2, Features: The upper portion of the spray-discharging outer cylinder (2) is threadedly connected to the upper joint (1), and the lower portion is threadedly connected to the outer cylinder (6).

4. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to claim 1, Features: The circulation mechanism assembly comprises an outer cylinder (6), a sealing core shaft (7), an outer sleeve (8), a shear pin (26) and a sealing sleeve (9); the upper end of the outer cylinder (6) is connected to the spraying outer cylinder (2) of the spraying mechanism assembly, and the lower end of the outer cylinder (6) is connected to the lower joint (14); the annular space between the lower part of the outer cylinder (6) and the outer sleeve (8) is hollow and communicates with the inner cavity of the lower joint (14) to form a liquid circulation channel; the sealing core shaft (7) is located at the upper end of the inner cavity of the outer sleeve (8), and the upper end of the sealing core shaft (7) is connected to the lower joint (14). The apex is a limit groove of the outer sleeve (8), and the lower end of the sealing core shaft (7) is connected to the reset mechanism assembly; an upper bypass valve (22) and a lower bypass valve (23) are arranged at the lower part of the sealing core shaft (7); the sealing sleeve (9) is located at the lower middle part of the inner cavity of the sealing core shaft (7) and is fixed to the inner cavity wall of the sealing core shaft (7) by means of a second shear pin (26); a sealing sleeve steel ball (21) is arranged on the upper end surface of the sealing sleeve (9), and the sealing sleeve steel ball (21) is seated on the upper end surface of the sealing sleeve (9) and seals the sealing sleeve (9).

5. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to claim 4, Features: In the initial state of the circulation mechanism assembly, the lower bypass valve (23) on the sealing core shaft (7) overlaps with the outer sleeve bypass valve (24) provided on the outer sleeve (6) to form a liquid flow channel; the sealing sleeve steel ball (21) is seated on the upper end surface of the sealing sleeve (9) and seals the sealing sleeve (9); after the sealing sleeve steel ball (21) is under pressure, the shear pin 2 (26) is sheared off, and the sealing sleeve (9) falls off, thereby sealing the lower bypass valve (23) on the sealing core shaft (7).

6. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to claim 4, Features: The upper end of the outer cylinder (6) is threadedly connected to the spray outer cylinder (2), and the lower end is threadedly connected to the lower joint (14).

7. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to claim 1, Features: The reset mechanism assembly comprises a sealing plug (10), a spring and a pressure transmission plug (15); the upper portion of the sealing plug (10) is connected to the sealing core shaft (7) of the circulation mechanism assembly, and the lower portion of the sealing plug (10) is connected to the spring; the upper end of the pressure transmission plug (15) is connected to the spring, and the lower end is fixed to the upper end surface of the inner cavity of the lower joint (14).

8. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to claim 7, Features: A gasket (13) is provided between the pressure transmission plug (15) and the upper end surface of the inner cavity of the lower joint (14).

9. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to claim 7, Features: The spring comprises an outer spring (11) and an inner spring (12), wherein the inner spring (12) is arranged inside the outer spring (11).

10. A device for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve according to any one of claims 1 to 9 provides a method for controlling the switch of a horizontal well fracturing string by a self-retractable spring plugging valve, Features: The specific steps are: Step 1: lower a fracturing string into the well, connect the upper end of the fracturing string to the wellhead, install an annular blowout preventer at the wellhead, and seal the wellhead; Step 2: In the initial state, the lower bypass valve (23) and the outer casing bypass valve (24) overlap, and the inner cavity of the fracturing string is in a free-flowing state; Step 3: insert a sealing sleeve steel ball (21) into the oil pipe, pressurize the oil pipe to at least 10 MPa, cut off the shear pin 2 (26), knock off the sealing sleeve (9), and close the lower bypass valve (23). At this time, the fracturing string is in a plugged state; Step 4: Continue to pressurize to 25-30 MPa, and hydraulically push the sealing core shaft (7) to compress the spring downward. When the upper bypass valve (22) and the outer casing bypass valve (24) are completely overlapped, the inner cavity of the fracturing string is in a smooth state; Step 5, performing fracturing construction according to the fracturing pumping procedure; Step 6: After the fracturing is completed, the oil pipe is released at a small flow rate, the spring pushes the sealing core shaft (7) upward, and the upper bypass valve (22) and the outer jacket bypass valve (24) are staggered and closed, so that the inner cavity of the fracturing pipe string is in a closed state, thereby achieving sealing inside the oil pipe; Step 7: close the annular blowout preventer, unload the wellhead, drag the fracturing string under pressure, adjust the position of the fracturing string, and perform layer-changing fracturing; Step 8, repeating steps 4 to 7 until all well sections are fractured; Step nine, when an emergency occurs, a blowout sleeve steel ball (20) is inserted into the oil pipe, the oil pipe is pressurized to 15 MPa, the shear pin 1 (4) is cut off, the blowout sleeve (5) is knocked off, and the blowout outer tube bypass valve (25) is opened, thereby forming an oil casing annulus circulation channel to achieve positive and reverse circulation well washing.

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