An openable and controllable differential pressure sliding sleeve and pressure testing method for fracturing and acidizing of oil and gas wells

Abstract

The application discloses an openable and controllable pressure-difference sliding sleeve for oil and gas well fracturing acidification and a pressure testing method, and is characterized in that the application is provided with a central pipe, a reversing piston and a piston auxiliary rebound mechanism, the piston auxiliary rebound mechanism is installed in an annulus formed by the central pipe and a spring outer cylinder and is located above the reversing piston; the reversing piston provided with a pressure testing track is connected with a piston connecting sleeve and is installed in a pressure operation cavity formed by the central pipe, a force transmission inner pipe, a piston outer cylinder and a sliding sleeve outer cylinder; the piston outer cylinder is connected with the reversing piston through a piston starting shear pin, a guide screw installed in the piston outer cylinder is connected with the pressure testing track of the reversing piston, and the sliding sleeve is connected with the sliding sleeve outer cylinder through a sliding sleeve opening shear pin. The application is an openable and controllable pressure-difference sliding sleeve which can be opened only after the well head is pressed once or more than once and pressure is released, the time for casing pressure testing is controllable, the operation is simple, the working reliability is high, the application has a remarkable use effect and can generate good economic benefits.

Description

Technical Field

[0001] This invention relates to a sliding sleeve for downhole stratified fracturing in oil and gas wells, and more specifically to an openable controllable differential pressure sliding sleeve and a pressure testing method for fracturing and acidizing in oil and gas wells. Background Technology

[0002] In the development of oil and gas fields, the development of many low-permeability oil and gas reservoirs generally requires fracturing, acidizing and other stimulation measures. The downhole tools used for fracturing and acidizing generally need to withstand harsh downhole environments such as high pressure and high temperature. Especially for multi-stage fracturing and completion projects, the process is complex, involves many types of downhole tools and has high technical requirements. The working performance of the supporting tools is crucial. For example, the sliding sleeve used for fracturing and acidizing. Once a problem occurs, it will inevitably lead to downhole accidents and cause huge economic losses.

[0003] As the formation conditions in new wells become increasingly complex and layered operations become more common, the reliability of sliding sleeves used in downhole fracturing and acidizing is receiving increasing attention.

[0004] Currently, conventional differential pressure opening fracturing sleeves are mainly used in tiered fracturing casing cementing and completion strings, installed at the very end of the string for the initial fracturing stage. They allow direct opening for fracturing operations without perforation, resulting in high efficiency and reduced operating costs, hence their widespread application. Differential pressure sleeves are mainly divided into direct-opening and delayed-opening types: direct-opening sleeves open directly through surface pressurization, which cannot meet the casing pressure testing requirements; delayed-opening sleeves have an internal delay structure, allowing for a delayed start when the surface pressurization reaches the casing test pressure; after the test, the sleeve opens. However, delayed-opening sleeves may experience problems such as excessively short opening times or failure to open properly due to changes in bottom hole conditions and construction / operational factors, thus failing to meet construction requirements.

[0005] Through searching, the following relevant patent technology emerged to solve the above problem: Patent application number 202123139997.3 discloses a toe end sliding sleeve that can be repeatedly tested. The above utility model includes an upper connector, a central tube, a movable guide ring, a piston rod, a piston, a stop ring, a ball, a spring, a rupture disc, and a lower connector.

[0006] The aforementioned sliding sleeve can fulfill the function of two pressure tests. The piston rod and piston are connected, and the hydraulic flow at both ends of the piston can be switched by changing the length of the piston reversing structure.

[0007] However, the piston operating chamber is an air chamber, which is affected by the internal and external pressure difference and airtightness. The internal pressure of the tool is also affected by the piston rod movement. After the rupture disc ruptures, the test pressure is also affected by the stress capacity of the reversing structure.

[0008] Patent application number 201820152248.3 discloses a testable toe-end sliding sleeve. This utility model includes a housing and an inner sliding sleeve disposed within the housing. The inner sliding sleeve comprises an upper inner sliding sleeve and a lower inner sliding sleeve. The upper inner sliding sleeve is equipped with a flow-limiting valve, and the lower inner sliding sleeve has a rupture disc on its side wall. During pressurization, the rupture disc ruptures, and the flow-limiting valve restricts the flow of grease in the oil chamber, thus delaying the opening of the sliding sleeve.

[0009] However, the sliding sleeve still has the problem of short opening time or failure to open normally.

[0010] Patent application number 201821811355.9 discloses a piston-type delayed-opening toe sleeve. The aforementioned utility model includes an upper connector, a housing, a delay mechanism, a central tube, an opening mechanism, and a lower connector. During operation, when the wellbore fluid reaches a set pressure value, the opening mechanism activates, driving the delay mechanism to activate. After a set time, the mechanism pushes the opening piston to move until the fracturing outer opening communicates with the fracturing inner opening.

[0011] However, the aforementioned utility model also has the problem of short opening time or inability to open normally.

[0012] Therefore, it is essential to provide an openable differential pressure sleeve for fracturing and acidizing oil and gas wells to solve the above problems. Summary of the Invention

[0013] The purpose of this invention is to provide a controllable differential pressure sleeve and a pressure testing method for use in oil and gas well fracturing and acidizing. This optimizes the internal structure of the sleeve and controls its opening time and frequency, thus solving the problems of short opening time or inability to open properly in existing sleeves used in downhole fracturing and acidizing completion projects in oil and gas wells. This ensures smooth completion of the project, reduces production costs, and improves economic efficiency.

[0014] The technical solution of this invention is: an openable controllable differential pressure sleeve for fracturing and acidizing oil and gas wells, comprising a central tube, a reversing piston, and a piston auxiliary rebound mechanism, wherein: the upper end of a force-transmitting inner tube with a pressure transmission hole is connected to the central tube, and the lower end is inserted into the sleeve; the central tube, the force-transmitting inner tube, and the sleeve are installed in the inner hole between the upper and lower joints; the spring outer cylinder with a piston balance hole, the piston outer cylinder, and the sleeve outer cylinder with a circulation port and a sleeve balance hole are connected to the outer circles of the upper and lower joints from top to bottom; the reversing piston with a test pressure track is connected to the piston connecting sleeve and installed in the pressure operating chamber formed by the central tube, the force-transmitting inner tube, the piston outer cylinder, and the sleeve outer cylinder; the piston auxiliary rebound mechanism is installed in the annular space formed by the central tube and the spring outer cylinder and is located above the reversing piston; the piston outer cylinder and the reversing piston are connected by a piston start shear pin; the guide screw installed in the piston outer cylinder is connected to the test pressure track of the reversing piston; and the sleeve and the sleeve outer cylinder are connected by a sleeve opening shear pin.

[0015] Preferably, the reversing piston is a non-uniform diameter cylindrical body, and the outer circumference of the cylinder is provided with an external threaded connection section, a piston starting shear pin groove, a test pressure track, a piston limiting connection section, and an external threaded connection section in sequence from top to bottom; a piston starting shear pin can be inserted into the piston starting shear pin groove, a guide screw can be inserted into the test pressure track, and a sealing ring groove is provided on both the inner and outer circumferences of the lower part of the piston limiting connection section, and a seal is installed therein.

[0016] Preferably, piston limiting blocks and piston limiting grooves are evenly distributed and staggered above the sealing ring groove in the piston limiting connection section of the reversing piston; in the reversing piston, the outer diameter of the piston limiting connection section is larger than the outer diameter of the body where the test pressure track is located.

[0017] Preferably, the test pressure track is composed of a bent asymmetrical track groove. The test pressure track has a track starting position, a track restoring position, a sliding sleeve opening position, and a device test pressure position. The test pressure track is arranged in parallel from top to bottom according to the height of the track groove. The device test pressure position is located higher than the sliding sleeve opening position and is parallel to it in the longitudinal direction.

[0018] Preferably, at least one set of test pressure rails is provided in the reversing piston, and the length of the sliding sleeve opening rail groove where the sliding sleeve opening position is located is greater than the length of the device test pressure rail groove where the device test pressure position is located; the inner circle of the piston connecting sleeve that is threadedly connected to the reversing piston is a stepped inner circle and is provided with an internal thread connecting section, a pressure transmission chamber and a limiting step from top to bottom. The internal thread connecting section is threadedly connected to the reversing piston, the pressure transmission chamber corresponds to the pressure transmission hole in the force transmission inner tube, and the limiting step cooperates with the limiting step above the pressure transmission hole of the force transmission inner tube.

[0019] Preferably, the piston outer cylinder is a non-uniform diameter cylindrical body and has a radially penetrating piston start shear pin hole and guide screw hole in the upper body. The piston start shear pin hole and guide screw hole are both threaded holes and can respectively accommodate piston start shear pin and guide screw. The other end of the guide screw is inserted into the starting position of the test pressure track.

[0020] Preferably, the piston outer cylinder inner cavity below the piston starting shear pin and guide screw is uniformly and alternately provided with outer cylinder limiting blocks and outer cylinder limiting slots, which can be inserted into the piston limiting slots and piston limiting blocks in the reversing piston.

[0021] Preferably, the sliding sleeve and the outer sleeve cylinder are both non-uniform diameter cylindrical bodies and overlap each other. After the sliding sleeve and the outer sleeve cylinder overlap, a pressure balance cavity is formed between them and the lower connector. This pressure balance cavity corresponds to the sliding sleeve balance hole. The outer sleeve cylinder and the sliding sleeve are connected by a sliding sleeve opening shear pin.

[0022] Preferably, a sliding sleeve starting shear pin is also installed between the upper end of the outer sleeve and the inner force transmission tube; at least two sliding sleeve starting shear pins are provided, at least three sliding sleeve opening shear pins are provided, and at least two pressure transmission holes are provided in the inner force transmission tube.

[0023] Preferably, the upper connector, spring outer cylinder, piston outer cylinder, sliding sleeve outer cylinder, and lower connector are threaded together sequentially from top to bottom; the piston auxiliary rebound mechanism includes a spacer ring, a spring, a support ring, a support ball, and an adjusting ring, which are installed sequentially from top to bottom within the annular space formed by the central tube and the spring outer cylinder; the upper end face of the adjusting ring and the lower end of the support ring are both provided with grooves, and the support ball is installed in the groove between the adjusting ring and the support ring; the lower inner circle of the adjusting ring is threadedly connected to the upper outer circle of the reversing piston and can move with the movement of the reversing piston.

[0024] The pressure testing method for the controllable differential pressure sleeve used in fracturing and acidizing of oil and gas wells includes the following steps: A. Pressurizing from the ground into the casing and breaking the piston start shear pin; B. Depressurizing after the first casing pressure test; C. Pressurizing again and opening the controllable differential pressure sleeve after all pressure tests are completed.

[0025] Compared with the prior art, the present invention has the following significant advantages: The device of the present invention is a controllable differential pressure sleeve that can only be opened after pressurizing at the wellhead once or more and depressurizing. The casing pressure test time is controllable, and the operation is simple and the reliability of the work is high.

[0026] The device of this invention can meet the requirements of overall casing pressure testing, and can change the position of the reversing sliding sleeve in the device by changing the long track groove-sliding sleeve opening track groove and the short track groove-device pressure testing track groove, thus completing the pressure testing and sliding sleeve opening operations, and the opening time is controllable. During pressure testing, the upper surface of the piston limiting block in the reversing piston contacts the lower surface of the outer cylinder limiting block in the piston outer cylinder, and the guide screw is not affected by the force generated during pressure testing. Therefore, it can meet the requirements of high pressure testing of the casing.

[0027] In the device of this invention, the pressure operation structure, consisting of the piston outer cylinder, central tube, reversing piston, and piston connecting sleeve, and the sliding sleeve opening structure, consisting of the sliding sleeve outer cylinder, sliding sleeve, and force transmission inner tube, are all independently designed, with the pressure operation chamber being an independent chamber. During pressure testing, the sliding sleeve in this invention is unaffected by internal pressure; it not only does not move but also experiences an upward force due to external pressure, preventing premature opening. Therefore, applying this invention can prevent all hazards caused by premature opening of the sliding sleeve due to factors such as misoperation. It solves the problem of premature opening or failure to open of the existing time-delay differential pressure sliding sleeve due to changes in formation parameters and operational factors, as well as all the drawbacks caused by premature opening or failure to open, significantly improving economic efficiency.

[0028] In summary, this invention has significant practical effects and great application value, and can generate good economic benefits. Attached Figure Description

[0029] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0030] Figure 1 This is a cross-sectional view of the schematic diagram of the controllable differential pressure sliding sleeve structure.

[0031] Figure 2 yes Figure 1 A three-dimensional structural diagram of the reversing piston.

[0032] In the diagram: 1. Upper connector; 2. Spring outer cylinder; 2. Piston balance hole 2-1; 3. Spacer ring; 4. Spring; 5. Central tube; 6. Support ring; 7. Support ball; 8. Adjusting ring; 9. Piston starting shear pin; 10. Guide screw; 11. Piston outer cylinder; 12. Reversing piston; 12. Track return position; 12. Sliding sleeve opening position; 12. Device pressure test position; 12. Piston limit block; 12. Piston limit groove; 12. Piston starting shear pin groove; 12. Track starting position; 12. Piston connecting sleeve; 13. Force transmission inner tube; 14. Pressure transmission hole; 14. Sliding sleeve starting shear pin; 15. Sliding sleeve opening shear pin; 16. Sliding sleeve outer cylinder; 17. Circulation port; 17. Sliding sleeve balance hole; 17. Sliding sleeve; 18. Lower connector; 19. Detailed Implementation

[0033] The accompanying drawings are for reference and illustration only and are not intended to limit the scope of protection of this invention. The technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] In the description of this invention, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0036] See Figures 1-2 As shown, an openable controllable differential pressure sleeve for fracturing and acidizing oil and gas wells includes a central tube 5, a reversing piston 12, and a piston auxiliary rebound mechanism. The inner tube 14, with a pressure transmission hole 14-1, is connected at its upper end to the central tube 5 and its lower end is inserted into the sleeve 18. The central tube 5, the inner tube 14, and the sleeve 18 are installed in the inner hole between the upper connector 1 and the lower connector 19. A spring outer cylinder 2 with a piston balance hole 2-1, a piston outer cylinder 11, and a sleeve outer cylinder 17 with a circulation port 17-1 and a sleeve balance hole 17-2 are connected sequentially from top to bottom to the upper connector 1 and the lower connector 19. The outer circle is connected; the reversing piston 12 with a test pressure track is connected to the piston connecting sleeve 13 and installed in the pressure operating chamber formed by the central tube 5, the force transmission inner tube 14, the piston outer cylinder 11 and the sliding sleeve outer cylinder 17; the piston auxiliary rebound mechanism is installed in the annular space formed by the central tube 5 and the spring outer cylinder 2 and is located above the reversing piston 12; the piston outer cylinder 11 and the reversing piston 12 are connected by the piston starting shear pin 9, the guide screw 10 installed in the piston outer cylinder 11 is connected to the test pressure track of the reversing piston 12, and the sliding sleeve 18 and the sliding sleeve outer cylinder 17 are connected by the sliding sleeve opening shear pin 16.

[0037] To overcome the problems of short opening time or inability to open normally in existing sliding sleeve devices, this invention connects the reversing piston 12 to the piston connecting sleeve 13 and installs it in the pressure operating chamber formed by the central tube 5, the force transmission inner tube 14, the piston outer cylinder 11, and the sliding sleeve outer cylinder 17. The spring outer cylinder 2 is provided with a piston balance hole 2-1, and the sliding sleeve outer cylinder 17 is provided with a circulation port 17-1 and a sliding sleeve balance hole 17-2. The pressure operating chamber is an independent chamber.

[0038] Because of the piston balance hole 2-1 in the outer spring cylinder 2 and the sliding sleeve balance hole 17-2 in the outer sliding sleeve cylinder 17, a sealed air chamber is not formed in the device of the present invention. The device of the present invention is not affected by the gas spring effect, nor by the airtightness of the pressure operating chamber and the pressure balance chamber. The reversing piston is subjected to hydraulic pressure and spring force, while the sliding sleeve is only subjected to hydraulic pressure, making the operating pressure of the reversing piston and the opening pressure of the sliding sleeve more stable.

[0039] During the pressure test, pressure is applied through the pressure transmission hole 14-1 in the inner tube 14. The sliding sleeve 18 is not affected by the internal pressure and does not move. Moreover, due to the external pressure, the sliding sleeve 18 is subjected to an upward force, which can prevent the sliding sleeve 18 from opening.

[0040] Therefore, the present invention can prevent the sliding sleeve 18 from opening prematurely due to factors such as misoperation.

[0041] Based on the above embodiment one, the present invention also has the following embodiments: A preferred embodiment: The reversing piston 12 is a non-uniform diameter cylindrical body and the outer circle of the cylinder is provided with an external threaded connection section, a piston starting shear pin groove 12-6, a test pressure track, a piston limiting connection section and an external threaded connection section from top to bottom; a piston starting shear pin 9 can be inserted into the piston starting shear pin groove 12-6, a guide screw 10 can be inserted into the test pressure track, and a sealing ring groove is provided on both the inner and outer circles of the lower part of the piston limiting connection section, and a sealing element is installed therein.

[0042] In a preferred embodiment: piston limiting blocks 12-4 and piston limiting grooves 12-5 are evenly distributed and staggered above the sealing ring groove in the piston limiting connecting section of the reversing piston 12; in the reversing piston 12, the outer diameter of the piston limiting connecting section is larger than the outer diameter of the body where the test pressure track is located.

[0043] In a preferred embodiment, the test pressure track is composed of a bent asymmetrical track groove. The test pressure track includes a track starting position 12-7, a track recovery position 12-1, a sliding sleeve opening position 12-2, and a device test pressure position 12-3. The test pressure track is arranged in parallel from top to bottom according to the height of the track grooves: the track starting position 12-7, the track recovery position 12-1, the device test pressure position 12-3, and the sliding sleeve opening position 12-2. The device test pressure position 12-3 is located higher than the sliding sleeve opening position 12-2 and is parallel to it in the longitudinal direction.

[0044] In a preferred embodiment: at least one set of test pressure tracks is provided in the reversing piston 12, and the length of the slide opening track groove where the slide opening position 12-2 is located is greater than the length of the device test pressure track groove where the device test pressure position 12-3 is located; the inner circle of the piston connecting sleeve 13, which is threadedly connected to the reversing piston 12, is a stepped inner circle and is provided with an internal thread connecting section, a pressure transmission chamber and a limiting step from top to bottom. The internal thread connecting section is threadedly connected to the reversing piston 12, the pressure transmission chamber corresponds to the pressure transmission hole 14-1 in the force transmission inner tube 14, and the limiting step cooperates with the limiting step above the pressure transmission hole 14-1 of the force transmission inner tube 14.

[0045] In a preferred embodiment: the piston outer cylinder 11 is a non-uniform diameter cylindrical body with a radially penetrating piston start shear pin hole and guide screw hole in the upper body. Both the piston start shear pin hole and the guide screw hole are threaded holes, capable of housing a piston start shear pin 9 and a guide screw 10, respectively. The other end of the guide screw 10 is inserted into the starting position 12-7 of the test pressure track. One end of the piston start shear pin 9 is threaded into the piston start shear pin hole on the piston outer cylinder 11, and the other end is installed in the piston start shear pin groove 12-6 in the reversing piston 12. This serves to limit the movement of the reversing piston 12 and the piston connecting sleeve 13 during casing installation and well completion, and before the overall casing pressure test, preventing the reversing piston 12 from prematurely opening the sliding sleeve 18.

[0046] In a preferred embodiment: The piston outer cylinder 11, located below the piston-starting shear pin 9 and guide screw 10, has uniformly distributed and staggered outer cylinder limiting blocks and grooves. These outer cylinder limiting blocks and grooves can interlock with the piston limiting grooves 12-5 and 12-4 in the reversing piston 12. During the pressure test, to prevent excessive stress on the guide screw 10, when the thrust generated by the pressure acting on the reversing piston 12 exceeds the shearing force of the piston-starting shear pin 9, the piston-starting shear pin 9 is sheared off. The reversing piston 12 moves upward and rotates a certain angle under the action of the guide screw 10 and the pressure test reversing track groove, entering the device pressure test track groove. When the guide screw 9 is about to reach the device pressure test position 13-3 of the pressure test track, the upper surface of the piston limiting block 12-4 in the reversing piston 12 contacts and is subjected to force with the lower surface of the outer cylinder limiting block in the piston outer cylinder 11. At this time, the piston connecting sleeve 13 also moves upward along with the reversing piston 12, and the limiting step at the lower part of its inner circle is close to the limiting step above the pressure transmission hole 14-1 in the force transmission inner tube 14. Since the guide screw 10 is not affected by the force generated during the pressure test of the sleeve, it can meet the test requirements of higher pressure.

[0047] In a preferred embodiment: both the sliding sleeve 18 and the outer sleeve cylinder 17 are non-uniform diameter cylindrical bodies and overlap each other. After the sliding sleeve 18 and the outer sleeve cylinder 17 overlap, a pressure balance cavity is formed between them and the lower connector 19. This pressure balance cavity corresponds to the sliding sleeve balance hole 17-2. The outer sleeve cylinder 17 and the sliding sleeve 18 are connected by the sliding sleeve opening shear pin 16.

[0048] In a preferred embodiment, a sliding sleeve starting shear pin 15 is also installed between the upper end of the outer sleeve cylinder 17 and the force transmission inner tube 14; at least two sliding sleeve starting shear pins 15 are provided, at least three sliding sleeve opening shear pins 16 are provided, and at least two pressure transmission holes 14-1 in the force transmission inner tube 14 are provided.

[0049] In a preferred embodiment: the upper connector 1, spring outer cylinder 2, piston outer cylinder 11, sliding sleeve outer cylinder 17, and lower connector 19 are sequentially threaded from top to bottom; the piston auxiliary rebound mechanism includes a spacer ring 3, a spring 4, a support ring 6, a support ball 7, and an adjusting ring 8, which are sequentially installed from top to bottom within the annular space formed by the central tube 5 and the spring outer cylinder 2; the upper end face of the adjusting ring 8 and the lower end of the support ring 6 are both provided with grooves, and the support ball 7 is installed in the groove between the adjusting ring 8 and the support ring 6; the lower inner circle of the adjusting ring 8 is threadedly connected to the upper outer circle of the reversing piston 12 and can move with the reversing piston 12, assisting in the reversing and resetting of the test pressure track in the reversing piston 12.

[0050] The pressure testing method for the controllable differential pressure sliding sleeve used in fracturing and acidizing of oil and gas wells includes the following steps: A. Pressurizing from the ground into the casing and breaking the piston start shear pin 9;

[0051] During this process: when the casing is pressure tested, the high-pressure fluid in the inner cavity of the device of the present invention enters the pressure operating chamber from the pressure transmission hole 14-1 of the force transmission inner tube 14 and acts on the lower part of the reversing piston 12.

[0052] When the thrust generated by the pressure acting on the reversing piston 12 is greater than the shearing force of the piston starting shear pin 9, the piston starting shear pin 9 is sheared, the reversing piston 12 moves upward and rotates at a certain angle under the action of the guide screw 10 and the track groove, and enters the test pressure reversing track groove.

[0053] When the guide screw 10 approaches the test pressure position 12-3 in the test pressure reversing track groove, the upper surface of the piston limiting block 12-4 in the reversing piston 12 contacts and is subjected to force with the lower surface of the outer cylinder limiting block in the piston outer cylinder 11. At this time, the piston connecting sleeve 13 also moves upward with the reversing piston 12, and the limiting step at the lower part of its inner circle is close to the limiting step position above the pressure transmission hole 14-1 in the force transmission inner tube 14. During the sleeve test pressure, the guide screw 10 is not affected by the force generated during the test pressure, thus meeting the test requirements for higher pressures.

[0054] B. After the first casing pressure test, the pressure is released. Under the elastic force of spring 4 in the piston auxiliary rebound mechanism, the reversing piston 12 moves downward and rotates a certain angle under the action of guide screw 10 and track groove in the pressure test track. Guide screw 10 enters track return position 12-1 in the reversing piston 12. At least one set of pressure test tracks should be set, or the number can be set according to the required number of pressure tests. Regardless of the number of sets of pressure test tracks, during each pressure test, the upper surface of the piston limiting block 12-4 in the reversing piston 12 contacts the lower surface of the outer cylinder limiting block in the piston outer cylinder 11, and is subjected to force.

[0055] C. After all pressure tests are completed, pressurize again and open the controllable differential pressure sleeve.

[0056] After all the pressure tests are completed, pressurize again to make the reversing piston 12 move upward, and under the action of the guide screw 10 and the track groove in the pressure test track, rotate a certain angle, enter the sliding sleeve opening track groove and enter the sliding sleeve opening position 12-2, thus opening the device of the present invention.

[0057] In this invention, the sliding sleeve opening track groove is longer than the device test pressure track groove. At this time, the piston limiting block 12-4 in the reversing piston 12 corresponds to the outer cylinder limiting slot in the inner circle of the piston outer cylinder 11. Therefore, the piston limiting block 12-4 in the reversing piston 12 enters the outer cylinder limiting slot in the piston outer cylinder 11, and the piston connecting sleeve 13 also continues to move upward with the reversing piston 12, so that the limiting step in the piston connecting sleeve 13 contacts the limiting step in the force transmission inner tube 14 and is subjected to force.

[0058] When the applied force is greater than the shearing force of the sliding sleeve starting shear pin 15, the sliding sleeve starting shear pin 15 is sheared, and the piston connecting sleeve 13 drives the force transmission inner tube 14 to move upward; when the force transmission inner tube 14 moves upward to the point where the sealing ring set in the inner hole of the sliding sleeve 18 can be exposed, the pressure in the inner cavity of the device of the present invention will act on the upper part of the sliding sleeve 18.

[0059] When the thrust generated by the pressure acting on the sliding sleeve 18 is greater than the shearing force of the sliding sleeve opening shear pin 16, the sliding sleeve opening shear pin 16 is sheared, the sliding sleeve 18 moves down and opens the circulation port 17-1 in the outer sleeve cylinder 17, the fracturing channel of the device of the present invention is opened, and fracturing construction can begin.

[0060] The embodiments described above are merely typical examples, but the present invention is not limited to these embodiments. Those skilled in the art can make modifications without departing from the spirit and teachings of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the inventive spirit and concept of the present invention should be included within the protection scope of the present invention. Therefore, the protection scope is not limited to the above description.

Claims

1. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells, provided with a central tube (5), a reversing piston (12) and a piston-assisted springback mechanism, characterized in that, The upper end of the force transmission inner tube (14) provided with pressure transmission holes (14-1) is connected with the central tube (5), and the lower end is inserted into the sliding sleeve (18), the central tube (5), the force transmission inner tube (14) and the sliding sleeve (18) are installed in the inner hole between the upper joint (1) and the lower joint (19); the spring outer cylinder (2) provided with piston balance holes (2-1), the piston outer cylinder (11) and the sliding sleeve outer cylinder (17) provided with circulation holes (17-1) and sliding sleeve balance holes (17-2) are connected with the outer circles of the upper joint (1) and the lower joint (19) from top to bottom; the reversing piston (12) provided with pressure test tracks is connected with the piston connecting sleeve (13) and installed in the pressure operation cavity formed by the central tube (5), the force transmission inner tube (14), the piston outer cylinder (11) and the sliding sleeve outer cylinder (17); the piston auxiliary rebound mechanism is installed in the annulus formed by the central tube (5) and the spring outer cylinder (2) and above the reversing piston (12); the piston outer cylinder (11) is connected with the reversing piston (12) through the piston starting shear pin (9), the guide screw (10) installed in the piston outer cylinder (11) is connected with the pressure test track of the reversing piston (12), and the sliding sleeve (18) is connected with the sliding sleeve outer cylinder (17) through the sliding sleeve opening shear pin (16).

2. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as claimed in claim 1, characterized in that, The reversing piston (12) is a non-equal-diameter cylindrical body, and the outer circle of the cylinder body is sequentially provided with an external thread connection section, a piston starting shear pin groove (12-6), a pressure test track, a piston limiting connection section and an external thread connection section from top to bottom; the piston starting shear pin groove (12-6) can insert the piston starting shear pin (9), the pressure test track can insert the guide screw (10), and the inner circle and the outer circle of the lower part of the piston limiting connection section are both provided with sealing ring grooves and install sealing elements therein.

3. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as claimed in claim 2, characterized in that, The piston limiting stop blocks (12-4) and the piston limiting stop grooves (12-5) are uniformly distributed and staggered above the sealing ring grooves in the piston limiting connection section of the reversing piston (12); in the reversing piston (12), the outer diameter of the piston limiting connection section is greater than the outer diameter of the body where the pressure test track is located.

4. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as set forth in claim 3, characterized in that, The pressure test track is composed of a bent asymmetric track groove, and the track starting position (12-7), the track recovery position (12-1), the sliding sleeve opening position (12-2) and the device pressure test position (12-3) are arranged in the pressure test track, and the device pressure test position (12-3) is higher than the sliding sleeve opening position (12-2) and parallel to it in the longitudinal direction.

5. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as set forth in claim 4, characterized in that, The pressure test track in the reversing piston (12) is provided with at least one set of track slots, and the length of the sleeve opening track slot at the sleeve opening position (12-2) is greater than the length of the device pressure test track slot at the device pressure test position (12-3); the inner circle of the piston connecting sleeve (13) threadedly connected with the reversing piston (12) is a stepped inner circle, and is provided with an inner threaded connection section from top to bottom, a pressure transmission cavity, and a limiting step, the inner threaded connection section is threadedly connected with the reversing piston (12), the pressure transmission cavity corresponds to the pressure transmission hole (14-1) in the force transmission inner tube (14), and the limiting step cooperates with the limiting step above the pressure transmission hole (14-1) in the force transmission inner tube (14).

6. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as set forth in claim 4, characterized in that, The piston outer cylinder (11) is a non-equal-diameter cylindrical body, and is provided with a piston starting shear pin hole and a guide screw hole in the upper body, both of which are threaded holes and can be respectively fitted with a piston starting shear pin (9) and a guide screw (10), and the other end of the guide screw (10) is inserted into the track starting position (12-7) of the pressure test track.

7. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as set forth in claim 6, characterized in that, The piston starting shear pin (9) and the guide screw (10) are uniformly distributed and staggered in the inner cavity of the piston outer cylinder (11) below, and are provided with an outer cylinder limiting block and an outer cylinder limiting slot, which can be mutually inserted with the piston limiting slot (12-5) and the piston limiting block (12-4) in the reversing piston (12).

8. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as set forth in claim 2, characterized in that, The sleeve (18) and the sleeve outer cylinder (17) are both non-equal-diameter cylindrical bodies and are overlapped with each other, and form a pressure balance cavity between the sleeve (18) and the lower joint (19) after being overlapped, which corresponds to the sleeve balance hole (17-2); the sleeve outer cylinder (17) and the sleeve (18) are connected through a sleeve opening shear pin (16).

9. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as set forth in claim 8, characterized in that, in The sleeve starting shear pin (15) is further provided between the upper end of the sleeve outer cylinder (17) and the force transmission inner tube (14); the sleeve opening shear pin (16) is provided with at least three, and the pressure transmission hole (14-1) in the force transmission inner tube (14) is provided with at least two.

10. An openable pressure-controlled differential sliding sleeve for fracturing and acidizing oil and gas wells as set forth in claim 9, characterized by, The upper joint (1), the spring outer cylinder (2), the piston outer cylinder (11), the sleeve outer cylinder (17), and the lower joint (19) are threadedly connected from top to bottom; the piston auxiliary rebound mechanism is provided with a spacer ring (3), a spring (4), a support ring (6), a support ball (7), and an adjusting ring (8), which are sequentially installed in the annulus formed by the central tube (5) and the spring outer cylinder (2) from top to bottom; the upper end surface of the adjusting ring (8) and the lower end of the support ring (6) are both provided with a groove, and the support ball (7) is installed in the groove between the adjusting ring (8) and the support ring (6); the lower inner circle of the adjusting ring (8) is threadedly connected with the upper outer circle of the reversing piston (12) and can move with the movement of the reversing piston (12).

11. The pressure testing method for opening the controllable pressure differential sliding sleeve for fracturing and acidizing of oil and gas wells according to any one of claims 1-10, characterized in that: The method comprises the following steps: A, from the ground to the casing pressure and the piston to start the shear pin (9) broken; B, the first casing pressure test after the end of the pressure relief; C, all the test pressure after the pressure, open the opening of the controllable differential sliding sleeve.

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