Pulling type two-stage tubing on-off valve and tubing pressure control method under pressure

Abstract

The application relates to the technical field of oilfield fracturing tools, and is a lifting and lowering type double-stage tubing on-off valve and a method for dragging a fracturing tubing under pressure, which comprises an upper joint, a central pipe, a pushing cylinder, a parallel cap, an outer cylinder and a lower joint. A sealing ring table which forms a sliding sealing cooperation with the outer wall of the pushing cylinder is arranged on the inner side of the middle part of the outer cylinder. Two groups of valve pieces are arranged on the inner side of the outer cylinder corresponding to the position between the sealing ring table and the lower joint. Each group of valve pieces comprises a supporting ring, a valve seat, a valve plate and a torsional spring. The application has a reasonable structure. The lifting and lowering type double-stage tubing on-off valve can be switched between the open position and the closed position through the operation of lifting and lowering the fracturing pipe column. When the lifting and lowering type double-stage tubing on-off valve is in the open position, the fracturing sand and liquid passing requirements can be met. When the lifting and lowering type double-stage tubing on-off valve is in the closed position, the tubing pressure can be controlled, and the dragging of the layer under pressure can be realized.

Description

Technical Field

[0001] This invention relates to the field of oilfield fracturing tools, specifically a lifting-and-releasing two-stage tubing switch valve and a pressure control method for pressure-driven fracturing oil control. Background Technology

[0002] Dragging tubing fracturing is a relatively mature horizontal well fracturing and stimulation technology, including coiled tubing fracturing with packers and tubing fracturing with packers. Among these, live-drafted tubing fracturing with dual-seal fracturing, combined with a live-worker rig, is a fracturing technology currently under development. This live-drafted fracturing technology consists of five parts: a live-drafted fracturing wellhead, tubing blowout preventer, dual-seal fracturing tool, and fracturing tubing. The process involves first installing the live-drafted fracturing wellhead, then running the dual-seal fracturing string, setting the packer and fracturing the target layer, closing the tubing blowout preventer after fracturing, pulling up the tubing for layer replacement fracturing while under pressure, and finally pulling out the fracturing tubing from the well while under pressure. The biggest advantage of this technology, which includes tubing and controlled blowout prevention, is its ability to perform live fracturing operations. The core tool for controlling tubing pressure is the tubing switch valve. To achieve live fracturing, this valve must effectively isolate the wellhead from formation pressure during tubing tripping, thus controlling the tubing. Lowering the tubing string opens the valve, connecting the wellhead tubing to the formation, allowing for the injection of fracturing fluid. Simultaneously, raising the tubing string closes the valve again, controlling tubing pressure and meeting the requirements for live fracturing layer replacement. However, currently, no tubing switch valve on the market meets all these performance requirements. Summary of the Invention

[0003] This invention provides a lift-and-release type two-stage tubing switch valve and a pressure control method for live-drive fracturing oil control, which overcomes the shortcomings of the prior art and can effectively solve the problem that existing tubing switch valves cannot meet the requirements of live-drive fracturing operations.

[0004] One of the technical solutions of this invention is achieved through the following measures: a lift-and-release type two-stage oil pipe switch valve, comprising an upper connector, a central pipe, a push cylinder, a cap, an outer cylinder, and a lower connector. The lower inner side of the upper connector is fixedly connected to the upper outer side of the central pipe, and the lower outer side of the central pipe is fixedly connected to the upper inner side of the push cylinder. A cap is fitted on the outer side of the central pipe corresponding to the upper position of the push cylinder, and the central pipe and the cap are fixedly connected together by shear pins. An outer cylinder is fitted on the outer side of the push cylinder, and the lower outer side of the cap is fixedly connected to the upper inner side of the outer cylinder. The lower inner side of the outer cylinder is fixedly connected to the upper outer side of the lower connector. An inner annular groove adapted to the push cylinder is provided on the upper inner side of the lower connector. The middle part of the outer cylinder... The inner side is provided with a sealing ring platform that forms a sliding seal with the outer wall of the push cylinder. The inner side of the outer cylinder corresponding to the position between the sealing ring platform and the lower connector is provided with two sets of valve components, one upper and one lower. Each set of valve components includes a support ring, a valve seat, a valve plate, and a torsion spring. The support ring and the valve seat are arranged sequentially from top to bottom inside the outer cylinder, and the upper part of the valve seat is fitted on the lower outer side of the support ring. The interior of the support ring and the valve seat respectively forms a passage for the push cylinder to pass through. The valve plate is hinged to the valve seat corresponding to the lower side of the support ring by a pin, and the pin is provided with a torsion spring for the valve plate to close the support ring. The push cylinder is located above the valve plate of the upper set of valve components, and the push cylinder can push open the valve plates of the two sets of valve components and insert into the inner ring groove when it moves downward relative to the outer cylinder.

[0005] The following are further optimizations and / or improvements to one of the above-mentioned inventive solutions:

[0006] The outer cylinder wall at the position corresponding to the cap and sealing ring platform can be provided with two sets of liquid passage channels, one above the other.

[0007] The aforementioned central tube and cap are designed to prevent rotation in a circumferential manner; anti-reverse screws are provided between the cap and the outer cylinder, and between the outer cylinder and the lower connector.

[0008] The inner wall of the aforementioned sealing ring platform may be provided with a first mounting ring groove and a second mounting ring groove at intervals. A retaining ring is installed in the first mounting ring groove, and an O-ring is installed in the second mounting ring groove. A third mounting ring groove is provided on the inner wall of the inner ring groove, and an O-ring is installed in the third mounting ring groove.

[0009] An O-ring may be provided between the outer wall of the support ring and the inner wall of the outer cylinder; an O-ring may be provided between the lower end face of the support ring and the upper end face of the valve plate; an O-ring may be provided between the lower inner side of the upper connector and the upper outer side of the central tube; and an O-ring may be provided between the lower outer side of the central tube and the upper inner side of the push cylinder.

[0010] The lower inner side of the upper connector and the upper outer side of the central tube can be fixedly connected together by threads. The lower outer side of the central tube and the upper inner side of the pusher are fixedly connected together by threads. The lower outer side of the cap and the upper inner side of the outer cylinder are fixedly connected together by threads. The lower inner side of the outer cylinder and the upper outer side of the lower connector are fixedly connected together by threads.

[0011] The second technical solution of the present invention is achieved through the following measures: a method for controlling the pressure of a fracturing oil system under pressure, comprising the following steps:

[0012] S1: Lower the fracturing string into the target well. The fracturing string includes, from top to bottom, a safety joint, hydraulic anchor, lift-and-drop two-stage tubing switch valve, top packer, throttle, sandblaster, bottom packer, and guide head, which are connected in series on the tubing.

[0013] S2: When the fracturing string reaches the target layer, first set the bottom sealing packer, then continue to lower the fracturing string and pressurize it to cut the shear pins. The pusher moves downward relative to the outer cylinder, so that the lifting and lowering two-stage tubing switch valve is in the open position, and then the fracturing pump injection operation is carried out.

[0014] S3: After the fracturing pumping operation of the target layer is completed, keep the fracturing string in place so that the lifting-release dual-stage tubing switch valve is in the open position, and perform reverse circulation well washing. After the reverse circulation well washing is completed, lift the fracturing string under pressure, and the pusher moves upward relative to the outer cylinder so that the lifting-release dual-stage tubing switch valve is in the closed position again. Continue to lift the fracturing string under pressure to the next target layer to complete the layer replacement.

[0015] S4: Repeat steps S2 to S3 until multi-segment fracturing is completed.

[0016] The following are further optimizations and / or improvements to the second invention solution described above:

[0017] In step S3 above, if the bottom seal packer is found to be stuck when lifting the fracturing string under pressure, the hydraulic turntable of the live-line working machine can be used to rotate the fracturing string. Torque is transmitted to the bottom seal packer through the upper connector, central tube, cap, outer cylinder, and lower connector to achieve rotational unblocking.

[0018] This invention features a rational structure. By raising and lowering the fracturing tubing string, the two-stage lifting-lowering tubing switch valve can be switched between open and closed positions. When open, the valve meets the requirements for sand and fluid flow during fracturing. When closed, it controls tubing pressure, enabling pressurized transfer between layers. The valve's opening and closing are achieved solely through the mechanical action of raising and lowering the fracturing tubing string, unaffected by flow rate, pressure differential, or other factors, ensuring stable and reliable operation. By using two sets of valves, the closing... The double seal when closed ensures high sealing reliability. Furthermore, when the fracturing tubing string is pulled up, the valve plate rebounds under the torsion of the torsion spring, closing the valve again. At this time, the valve plate, under the upward pressure at the bottom of the well, tightly abuts against the support ring, achieving well pressure-assisted sealing and further improving sealing reliability. When the lift-and-release dual-stage tubing switch valve is in the open position, the two sets of valves are located in a closed annular cavity formed between the pusher, outer cylinder, and lower connector, unaffected by fracturing sand and fluid leakage, avoiding wear on the valves and extending the equipment's service life. Attached Figure Description

[0019] Appendix Figure 1 This is a schematic diagram of the main sectional view of the lifting-release type two-stage oil pipe switch valve in the closed position in Embodiments 1 and 2 of the present invention.

[0020] Appendix Figure 2 This is a schematic diagram of the main sectional view of the lifting-release type two-stage oil pipe switch valve in the open position in Embodiments 1 and 2 of the present invention.

[0021] Appendix Figure 3 This is a schematic diagram of the main sectional view of the valve component in Embodiments 1 and 2 of the present invention.

[0022] Appendix Figure 4 This is a schematic diagram of the fracturing tubing in Embodiments 1 and 2 of the present invention.

[0023] The codes in the attached diagram are as follows: 1 is the upper connector, 2 is the central tube, 3 is the push cylinder, 4 is the cap, 5 is the outer cylinder, 6 is the lower connector, 7 is the shear pin, 8 is the inner ring groove, 9 is the sealing ring platform, 10 is the support ring, 11 is the valve seat, 12 is the valve plate, 13 is the torsion spring, 14 is the pin, 15 is the fluid passage, 16 is the anti-removal screw, 17 is the retaining ring, 18 is the O-ring seal, 19 is the upper oil pipe, 20 is the safety connector, 21 is the hydraulic anchor, 22 is the lift-and-release two-stage oil pipe switch valve, 23 is the top sealing packer, 24 is the throttle, 25 is the sandblaster, 26 is the bottom sealing packer, and 27 is the guide head. Detailed Implementation

[0024] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0025] In this invention, for ease of description, the description of the relative positions of the components is based on the appendix to the specification. Figure 1 The layout is described using a diagrammatic method, such as front, back, top, bottom, left, right, etc. The positional relationships are determined based on the layout direction of the attached diagram in the instruction manual.

[0026] The present invention will be further described below with reference to embodiments and accompanying drawings:

[0027] Example 1: As shown in the attached document Figure 1-4 As shown, the lift-and-release type two-stage oil pipe switch valve includes an upper connector 1, a central pipe 2, a push cylinder 3, a cap 4, an outer cylinder 5, and a lower connector 6. The lower inner side of the upper connector 1 is fixedly connected to the upper outer side of the central pipe 2. The lower outer side of the central pipe 2 is fixedly connected to the upper inner side of the push cylinder 3. A cap 4 is fitted on the outer side of the central pipe 2 corresponding to the upper position of the push cylinder 3, and the central pipe 2 and the cap 4 are fixedly connected together by a shear pin 7. An outer cylinder 5 is fitted on the outer side of the push cylinder 3. The lower outer side of the cap 4 is fixedly connected to the upper inner side of the outer cylinder 5. The lower inner side of the outer cylinder 5 is fixedly connected to the upper outer side of the lower connector 6. The upper inner side of the lower connector 6 is provided with an inner annular groove 8 that matches the push cylinder 3. The middle inner side of the outer cylinder 5 is provided with a sealing ring that forms a sliding seal with the outer wall of the push cylinder 3. Platform 9, corresponding to the position between sealing ring platform 9 and lower connector 6, is provided with two sets of valve components on the inner side of the outer cylinder 5. Each set of valve components includes a support ring 10, a valve seat 11, a valve plate 12 and a torsion spring 13. The support ring 10 and valve seat 11 are arranged in the outer cylinder 5 from top to bottom, and the upper part of the valve seat 11 is sleeved on the lower outer side of the support ring 10. The interior of the support ring 10 and the valve seat 11 respectively forms a passage for the push cylinder 3 to pass through. The valve plate 12 is hinged to the valve seat 11 at the lower position of the support ring 10 by a pin 14, and the pin 14 is provided with a torsion spring 13 for the valve plate 12 to close the support ring 10. The push cylinder 3 is located above the valve plate 12 of the upper set of valve components, and the push cylinder 3 can push open the valve plates 12 of the two sets of valve components and insert into the inner ring groove 8 when it moves downward relative to the outer cylinder 5.

[0028] In use, the safety connector 20, hydraulic anchor 21, lift-and-release two-stage tubing switch valve 22, top sealing packer 23, throttle 24, sandblasting device 25, bottom sealing packer 26, and guide head 27 are connected in series from top to bottom on the tubing 19 to form a fracturing string. Specifically, the top sealing packer 23 is a Y344 packer or a K344 packer, the bottom sealing packer 26 is a TDY211 packer, the upper connector 1 is connected to the lower part of the hydraulic anchor 21, and the lower connector 6 is connected to the top of the top sealing packer 23. During the fracturing tubing string insertion process, the tubing string consisting of the upper connector 1, central tube 2, and pusher 3, and the tubing string consisting of the cap 4, outer tube 5, and lower connector 6 are in the open state. Under the torsional force of the torsion spring 13, the upper end face of the valve plate 12 of the two sets of valve components abuts against the lower end face of the corresponding support ring 10, thereby closing the lower end opening of the support ring 10. The lifting-type two-stage tubing switch valve is in the closed position. The shear pin 7 provides a limiting force to ensure that the pusher 3 and the outer tube 5 do not move relative to each other during insertion. The fracturing tubing string is lowered to the pre-positioned... After positioning, first set the bottom sealing packer 26, then continue lowering the fracturing tubing string to apply pressure. The pressure exceeds the shearing force of the shear pin 7, causing it to break. The pusher 3 descends relative to the outer cylinder 5, pushing open the valve plates 12 of both sets of valves until the lower end of the pusher 3 is inserted into the inner annular groove 8 of the lower connector 6. At this point, the internal passage of the lift-and-release dual-stage tubing switch valve is connected, and the lift-and-release dual-stage tubing switch valve is in the open position. The upper tubing 19 is connected to the formation, thus meeting the requirements for pumping sand fluid during fracturing. When the target well is not fracturing... After the fracturing operation, the fracturing string is lifted, and the pusher 3 moves upward relative to the outer cylinder 5. The valve plates 12 of the two sets of valves rebound under the torsion of the torsion spring 13 and close the lower opening of the support ring 10 again. The lifting-release dual-stage tubing switch valve is closed again, thereby isolating the upper tubing 19 from the formation pressure. Then, the fracturing string is lifted under pressure by the live-line working machine to realize the replacement of the fracturing segment. Specifically, in this embodiment, the shearing force of the shear pin 7 is 30kN, and the pressure applied when lowering the fracturing string can be 33kN.

[0029] The lifting-and-lowering dual-stage tubing switch valve of this application can switch between open and closed positions by lifting and lowering the fracturing tubing string. When in the open position, the valve meets the requirements for fracturing sand and fluid passage. When in the closed position, it controls the tubing pressure, enabling pressurized drag-and-transfer of layers. The opening and closing of the valve is achieved solely through the mechanical action of lifting and lowering the fracturing tubing string, and is unaffected by factors such as flow rate or pressure differential. By setting two sets of valve components, a double seal is achieved when closed, ensuring reliable sealing. It has good performance. In addition, when the fracturing tubing string is pulled up, the valve plate 12 rebounds under the torsion of the torsion spring 13 and closes the valve again. At this time, the valve plate 12 is tightly pressed against the support ring 10 by the upward force of the bottom hole pressure, realizing the well pressure-assisted sealing function and further improving the sealing reliability. When the lift-and-release type two-stage tubing switch valve is in the open position, the two sets of valves are located in the closed annular cavity formed between the push cylinder 3, the outer cylinder 5, and the lower connector 6, and are not affected by fracturing sand and fluid. This avoids fracturing sand and fluid wear on the valves and extends the service life of the equipment.

[0030] The above embodiment one can be further optimized and / or improved according to actual needs:

[0031] As attached Figure 1-2 As shown, two sets of liquid passage channels 15 are provided through the outer cylinder 5 at the position corresponding to the position between the cap 4 and the sealing ring platform 9. According to the requirements, each set of liquid passage channels 15 includes multiple liquid passage channels 15 arranged at intervals along the circumference of the outer cylinder 5. In this embodiment, the liquid passage channel 15 is a 0.2*30mm slit. The liquid passage channels 15 are used to balance the internal and external pressure difference between the annular cavity formed between the push cylinder 3 and the outer cylinder 5 and the outer space of the outer cylinder 5.

[0032] As attached Figure 1-2 As shown, the central tube 2 and the cap 4 are circumferentially anti-rotationally fitted; anti-reverse screws 16 are provided between the cap 4 and the outer cylinder 5, and between the outer cylinder 5 and the lower connector 6. The central tube 2 and the cap 4 are circumferentially anti-rotationally fitted, so that the two can transmit torque when assembled together. Therefore, when the bottom seal packer 26 is found to be stuck when the fracturing string is lifted, the hydraulic turntable of the live-line working machine can be used to rotate the fracturing string, and the torque is transmitted to the bottom seal packer 26 through the upper connector 1, central tube 2, cap 4, outer cylinder 5, and lower connector 6 to achieve rotational release. Specifically, the outer contour of the cross-section of the central tube 2 is a regular hexagon, and the inner contour of the cross-section of the cap 4 is a regular hexagon that matches the outer contour of the cross-section of the central tube 2. Therefore, when the central tube 2 and the cap 4 are fitted together, they cannot rotate relative to each other, thus achieving a circumferential anti-rotation fit.

[0033] As attached Figure 1-2As shown, the inner wall of the sealing ring platform 9 is provided with a first mounting ring groove and a second mounting ring groove spaced vertically. A retaining ring 17 is installed in the first mounting ring groove, and an O-ring seal 18 is installed in the second mounting ring groove. This achieves a sliding sealing fit between the sealing ring platform 9 and the outer wall of the push cylinder 3.

[0034] As attached Figure 1-2 As shown, a third mounting ring groove is provided on the inner wall of the inner ring groove 8, and an O-ring 18 for sealing with the push cylinder 3 is installed in the third mounting ring groove. Thus, when the push cylinder 3 is inserted into the inner ring groove 8, the push cylinder 3 and the lower connector 6 are sealed together, which can effectively prevent the fracturing construction pump sand from entering the closed annular cavity formed between the push cylinder 3, the outer cylinder 5, and the lower connector 6.

[0035] As attached Figure 1-2 As shown, an O-ring 18 is provided between the outer wall of the support ring 10 and the inner wall of the outer cylinder 5; an O-ring 18 is provided between the lower end face of the support ring 10 and the upper end face of the valve plate 12; an O-ring 18 is provided between the lower inner side of the upper connector 1 and the upper outer side of the central tube 2; and an O-ring 18 is provided between the lower outer side of the central tube 2 and the upper inner side of the push cylinder 3.

[0036] Specifically, the lower inner side of the upper connector 1 and the upper outer side of the central tube 2 are fixedly connected together by threads, the lower outer side of the central tube 2 and the upper inner side of the push cylinder 3 are fixedly connected together by threads, the lower outer side of the cap 4 and the upper inner side of the outer cylinder 5 are fixedly connected together by threads, and the lower inner side of the outer cylinder 5 and the upper outer side of the lower connector 6 are fixedly connected together by threads.

[0037] Example 2: As shown in the attached document Figure 1-4 As shown, the pressure control method for live fracturing oil includes the following steps:

[0038] S1: Lower the fracturing string into the target well. The fracturing string includes, from top to bottom, a safety joint 20, a hydraulic anchor 21, a lift-and-drop two-stage tubing switch valve 22, a top packer 23, a throttle 24, a sandblaster 25, a bottom packer 26, and a guide head 27, which are connected in series on the tubing 19.

[0039] S2: When the fracturing string reaches the target layer, first set the bottom sealing packer 26, then continue to lower the fracturing string and pressurize it so that the shear pin 7 is sheared off. The pusher 3 moves downward relative to the outer cylinder 5, so that the lifting and lowering two-stage tubing switch valve 22 is in the open position, and then the fracturing pump injection operation is carried out.

[0040] S3: After the fracturing pumping operation of the target layer is completed, keep the position of the fracturing string still so that the lifting-release dual-stage tubing switch valve 22 is in the open position, and perform reverse circulation well washing. After the reverse circulation well washing is completed, lift the fracturing string under pressure, and push cylinder 3 moves upward relative to outer cylinder 5 so that the lifting-release dual-stage tubing switch valve 22 is in the closed position again. Continue to lift the fracturing string under pressure to the next target layer to complete the layer replacement.

[0041] S4: Repeat steps S2 to S3 until multi-segment fracturing is completed.

[0042] Specifically, in step S2, when the fracturing string reaches the target layer, which is located between the top packer 23 and the bottom packer 26, the top packer 23 is set by the throttling pressure difference generated by the sandblaster 25 during fracturing pumping. The fracturing fluid enters the target layer through the sandblaster 25. After the target layer fracturing is completed, the pump is stopped, and the top packer 23 is released. During the fracturing pumping process, the hydraulic anchor provides support to ensure that the pusher 3 will not detach from the lower joint 6 and valve due to the creep of the fracturing string. The pressure control method of the live-drive fracturing oil control in this method can switch the lifting and lowering of the fracturing string between the open and closed positions of the lifting and lowering type two-stage tubing switch valve. When the lifting and lowering type two-stage tubing switch valve is in the open position, it can meet the fracturing sand and fluid requirements. When the lifting and lowering type two-stage tubing switch valve is in the closed position, it can control the tubing pressure, realizing live-drive transfer, which greatly improves the efficiency of live-drive fracturing construction.

[0043] The above embodiment 2 can be further optimized and / or improved according to actual needs:

[0044] Specifically, in step S3, if the bottom packer 26 is found to be stuck when the fracturing string is lifted under pressure, the hydraulic turntable of the live-line working machine can be used to rotate the fracturing string. Torque is transmitted to the bottom packer 26 through the upper connector 1, central tube 2, cap 4, outer cylinder 5, and lower connector 6 to achieve rotational unblocking.

[0045] The above technical features constitute the preferred embodiment of the present invention, which has strong adaptability and optimal implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the requirements of different situations.

Claims

1. A method for controlling the pressure of a fracturing oil system under pressure, characterized in that... Includes the following steps: S1: Lower the fracturing string into the target well. The fracturing string includes, from top to bottom, a safety joint, hydraulic anchor, lift-and-drop two-stage tubing switch valve, top packer, throttle, sandblaster, bottom packer, and guide head, which are connected in series on the tubing. S2: When the fracturing string reaches the target layer, first set the bottom sealing packer, then continue to lower the fracturing string and pressurize it to cut the shear pins. The pusher moves downward relative to the outer cylinder, so that the lifting and lowering two-stage tubing switch valve is in the open position, and then the fracturing pump injection operation is carried out. S3: After the fracturing pumping operation of the target layer is completed, keep the fracturing string in place so that the lifting-release dual-stage tubing switch valve is in the open position, and perform reverse circulation well washing. After the reverse circulation well washing is completed, lift the fracturing string under pressure, and the pusher moves upward relative to the outer cylinder so that the lifting-release dual-stage tubing switch valve is in the closed position again. Continue to lift the fracturing string under pressure to the next target layer to complete the layer replacement. S4: Repeat steps S2 to S3 until multi-segment fracturing is completed; The lift-and-release type two-stage tubing switch valve includes an upper connector, a central tube, a push cylinder, a cap, an outer cylinder, and a lower connector. The lower inner side of the upper connector is fixedly connected to the upper outer side of the central tube. The lower outer side of the central tube is fixedly connected to the upper inner side of the push cylinder. A cap is fitted on the outer side of the central tube corresponding to the upper position of the push cylinder, and the central tube and the cap are fixedly connected together by shear pins. An outer cylinder is fitted on the outer side of the push cylinder. The lower outer side of the cap is fixedly connected to the upper inner side of the outer cylinder. The lower inner side of the outer cylinder is fixedly connected to the upper outer side of the lower connector. The upper inner side of the lower connector has an inner annular groove that fits the push cylinder. The middle inner side of the outer cylinder has a groove that forms a sliding contact with the outer wall of the push cylinder. The sealing ring platform of the dynamic seal is fitted with two sets of valve components on the inner side of the outer cylinder corresponding to the position between the sealing ring platform and the lower connector. Each set of valve components includes a support ring, a valve seat, a valve plate and a torsion spring. The support ring and the valve seat are arranged in the outer cylinder from top to bottom, and the upper part of the valve seat is fitted on the lower outer side of the support ring. The interior of the support ring and the valve seat respectively forms a passage for the push cylinder to pass through. The valve plate is hinged to the valve seat corresponding to the lower side of the support ring by a pin, and the pin is provided with a torsion spring for the valve plate to close the support ring. The push cylinder is located above the valve plate of the upper set of valve components, and the push cylinder can push open the valve plates of the two sets of valve components and insert into the inner ring groove when it moves downward relative to the outer cylinder.

2. The pressure control method for live fracturing oil wells according to claim 1, characterized in that... In step S3, if the bottom packer is found to be stuck when lifting the fracturing string under pressure, the hydraulic turntable of the live-line working machine can be used to rotate the fracturing string. Torque is transmitted to the bottom packer through the upper connector, central tube, cap, outer cylinder, and lower connector to achieve rotational unblocking.

3. The pressure control method for live fracturing oil wells according to claim 1, characterized in that... Two sets of liquid passages are provided through the outer cylinder wall at the position between the cap and the sealing ring platform.

4. The pressure control method for pressurized fracturing oil under pressure according to claim 1 or 3, characterized in that... The central tube and the cap are circumferentially anti-rotation fitted; anti-reverse screws are provided between the cap and the outer cylinder, and between the outer cylinder and the lower connector.

5. The pressure control method for pressurized fracturing oil under pressure according to claim 1 or 3, characterized in that... The inner wall of the sealing ring platform is provided with a first mounting ring groove and a second mounting ring groove at intervals. A retaining ring is installed in the first mounting ring groove and an O-ring is installed in the second mounting ring groove. A third mounting ring groove is provided on the inner wall of the inner ring groove, and an O-ring is installed in the third mounting ring groove.

6. The pressure control method for live fracturing oil wells according to claim 4, characterized in that... The inner wall of the sealing ring platform is provided with a first mounting ring groove and a second mounting ring groove at intervals. A retaining ring is installed in the first mounting ring groove and an O-ring is installed in the second mounting ring groove. A third mounting ring groove is provided on the inner wall of the inner ring groove, and an O-ring is installed in the third mounting ring groove.

7. The pressure control method for pressurized fracturing oil under pressure according to claim 1, 3, or 6, characterized in that... An O-ring is provided between the outer wall of the support ring and the inner wall of the outer cylinder; an O-ring is provided between the lower end face of the support ring and the upper end face of the valve plate; an O-ring is provided between the lower inner side of the upper connector and the upper outer side of the central tube; and an O-ring is provided between the lower outer side of the central tube and the upper inner side of the push cylinder.

8. The pressure control method for pressurized fracturing oil under pressure according to claim 1, 3, or 6, characterized in that... The lower inner side of the upper connector and the upper outer side of the central tube are fixedly connected together by threads. The lower outer side of the central tube and the upper inner side of the push cylinder are fixedly connected together by threads. The lower outer side of the cap and the upper inner side of the outer cylinder are fixedly connected together by threads. The lower inner side of the outer cylinder and the upper outer side of the lower connector are fixedly connected together by threads.

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