Degradable swelling temporary plugging device for wellbore and method of use thereof

Abstract

The present application relates to a kind of degradable expansion temporary plugging device for wellbore and its use method, including plugging shedding component, first plugging component, flexible connection component, second plugging component and plugging guide component, the plugging shedding component, first plugging component, flexible connection component, second plugging component and plugging guide component are detachably connected and communicated between each other.The whole device material uses controllable dissolving aluminum alloy, soluble and controllable degradable material processing of controllable degradable rubber, in actual operation, in the temporary plugging operation of the tubing expansion in the high-deviation well, the well section with large dogleg and the horizontal well operation, with high construction efficiency, strong wellbore applicability and overall controllable degradation, overcome the technical problem that the rigidity part length is too large in the conventional tubing plugging construction tool and the passability is poor in the well section with large dogleg.

Description

Technical Field

[0001] This invention belongs to the technical field of oil and gas field development, and in particular to a biodegradable expandable temporary plugging device and its usage method for construction of oil tubing operations in lost circulation wells. It is applied to temporary plugging of lost circulation in gas wells with production tubing and large lost circulation well operations. Background Technology

[0002] When operating injection and production wells in oil and gas reservoirs or gas storage facilities, well control operations are often required. However, these wells often suffer from problems such as formation loss and formation contamination caused by well control fluid, especially when the wellbore has a production tubing, pressure, and alternating blowouts. Conventional well control methods cannot be used, which brings considerable difficulties and may even make the operation impossible.

[0003] Currently, the known solutions both domestically and internationally mainly employ chemical plugging agents or physical methods such as granular plugging agents. However, both chemical and physical plugging methods have drawbacks such as poor stability and difficulty in restoring formation permeability, and cannot simultaneously meet the technical requirements of "no damage to the formation, ability to operate under pressure, and passage through production tubing."

[0004] Currently known mechanical plugging technologies typically employ longer bridge plugs to accommodate operations with high expansion ratios. For example, the total length of a cable-set expansion-type tubing bridge plug (including the bridge plug and setting tool) often reaches 6-9 meters. Due to the excessive length of its rigid portion, the passage of tools in demanding well sections with high doglegs, such as highly deviated and horizontal wells, is difficult to guarantee, often resulting in technical challenges in tool insertion. Furthermore, because these high expansion-ratio bridge plugs are non-degradable, the difficulty in removing them after operation is also a frequent issue. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and propose a biodegradable expansion temporary plugging device for wells with high construction efficiency, strong wellbore applicability, safe release, and overall controllable degradation, as well as its usage method. This solves the technical problem that conventional tubing plugging tools have poor passability in well sections with large doglegs due to the excessive length of their rigid parts.

[0006] The technical problem solved by this invention is achieved through the following technical solution:

[0007] On one hand, the present invention provides a biodegradable expandable temporary plugging device for wellbore, including a plugging detachment component, a first plugging component, a flexible connection component, a second plugging component, and a plugging guide component. One end of the plugging detachment component is detachably connected to the coiled tubing, and the other end is detachably connected to one end of the first plugging component. The other end of the first plugging component is detachably connected to one end of the flexible connection component. The other end of the flexible connection component is detachably connected to one end of the second plugging component. The other end of the second plugging component is detachably connected to one end of the plugging guide component. The plugging detachment component, the first plugging component, the flexible connection component, the second plugging component, and the plugging guide component are interconnected. The plugging detachment component is used to separate the coiled tubing connector from the biodegradable expandable temporary plugging device. The first and second plugging components are used to set the well section. The plugging guide component is used to quickly lower the biodegradable expandable temporary plugging device into the well section to be plugged.

[0008] Preferably, the sealing and detachment assembly includes a sealing and detachment upper connector, a shear pin, and a release handle. One end of the release handle is fitted inside one end of the sealing and detachment upper connector and engages with the shear pin. The shear pin is used to separate the release handle from the sealing and detachment upper connector. The sealing and detachment upper connector has a hollow structure with a trapezoidal female buckle on the inner wall of one end and a sealing and detachment upper connector mounting hole on the side wall of the other end.

[0009] The release handle has a hollow structure with a semi-circular groove on the inner wall of one end and a hollow ball head on the outer wall of the other end. The outer wall of the release handle has a release handle mounting hole, a first release handle sealing ring groove and a second release handle sealing ring groove near the semi-circular groove. The shear pin is connected to the sealing and detachment upper connector and the release handle through the sealing and detachment upper connector mounting hole and the liquid release handle mounting hole, respectively.

[0010] Preferably, the first sealing assembly includes a first rubber tube, a first rubber tube upper pressure cap, a first rubber tube lower pressure cap, a first rubber tube upper connector, a first rubber tube lower connector, a first rubber stopper check valve, and a first rubber stopper center tube. Both ends of the first rubber tube are detachably connected to one end of the first rubber tube upper connector and one end of the first rubber tube lower connector, respectively. The other ends of the first rubber tube upper connector and the first rubber tube lower connector are detachably connected to one end of the first rubber tube upper pressure cap and one end of the first rubber tube lower pressure cap, respectively. The other end of the first rubber tube upper pressure cap is detachably connected to one end of the release mechanism relative to the release mechanism semicircular groove. The other end of the first rubber tube lower pressure cap is detachably connected to the flexible connection assembly.

[0011] The upper and lower pressure caps of the first rubber tube have the same hollow structure, and a ball head groove that mates with the hollow ball head is provided on the inner wall of one end of the first rubber tube, while a female buckle is provided on the other end.

[0012] The upper and lower connectors of the first rubber tube have the same trapezoidal hollow structure, with male snap-fits at both ends. The ends of the upper and lower connectors relative to the first rubber tube respectively engage with the upper and lower pressure caps of the first rubber tube relative to the ball head groove. The first rubber stopper check valve is located inside the upper connector of the first rubber tube, and serves as a one-way connection between the sealing / dislodging assembly and the first sealing assembly.

[0013] The first rubber tube has female buckles at both ends, which respectively engage with one end of the upper and lower connectors of the first rubber tube relative to the upper and lower pressure caps of the first rubber tube. The middle part of the first rubber tube is configured as an expandable rubber tube, comprising an inner expandable rubber tube and an outer expandable rubber tube. The central tube of the first rubber stopper is disposed inside the first rubber tube, and its two ends are respectively engaged with the upper and lower connectors of the first rubber tube. The central tube of the first rubber stopper is used to pressurize and expand the inner and outer expandable rubber tubes of the first rubber tube. The central tube of the first rubber stopper has two or more sieve-shaped flow holes in its middle section.

[0014] The first rubber stopper flow valve includes a flow valve conical stopper, a rubber spring, and a metal gasket screen. The flow valve conical stopper, the rubber spring, and the metal gasket screen are combined using a rubber vulcanization process. The flow valve conical stopper and the rubber spring are made of expanded rubber and have a soluble magnesium alloy protective layer on their outer surface. The metal gasket screen is made of a soluble aluminum-based alloy.

[0015] The inner wall of the upper pressure cap of the first rubber tube is provided with a sealing ring groove for the upper pressure cap and a sealing ring groove for the upper pressure cap of the first rubber tube near the ball head groove, and the inner wall of the lower pressure cap of the first rubber tube is provided with a sealing ring groove for the lower pressure cap of the first rubber tube and a sealing ring groove for the lower pressure cap of the first rubber tube near the ball head groove.

[0016] Preferably, the inner and outer expandable rubber layers of the first rubber sleeve are a composite structure of biodegradable rubber and soluble aluminum alloy. The outer surfaces of both the inner and outer expandable rubber layers are provided with a cold-sprayed rubber vulcanized layer containing TiN particles. This allows the first rubber sleeve to be firmly sealed within the wellbore cavity after expansion and to self-degrade within a predetermined time, depending on the wellbore temperature and alkaline liquid conditions.

[0017] The first rubber tube, the upper pressure cap of the first rubber tube, the lower pressure cap of the first rubber tube, the upper connector of the first rubber tube, the lower connector of the first rubber tube, the one-way valve of the first rubber stopper, and the central tube of the first rubber stopper are made of soluble aluminum-based alloy, which can be slowly dissolved in NaOH aqueous solution into micron-sized metal powder;

[0018] Preferably, the flexible connection assembly includes a first movable connecting section, a second movable connecting section, an elbow connector, an upper pressure cap for the elbow connector, and a lower pressure cap for the elbow connector. The first movable connecting section, the second movable connecting section, the elbow connector, the upper pressure cap for the elbow connector, and the lower pressure cap for the elbow connector are detachably connected to each other and are in communication.

[0019] The toggle connector is a hollow tubular structure with male buckles at both ends. The upper and lower pressure caps of the toggle connector have the same hollow tubular structure, with a female buckle at one end and a ball joint groove on the inner wall of the other end. The first and second movable connecting sections have the same hollow tubular structure, with hollow ball joints at both ends that mate with the ball joint grooves. The upper and lower pressure caps of the toggle connector have female buckles at one end that engages with the toggle connector, and the other end engages with the first and second movable connecting sections.

[0020] The first movable connecting joint, the second movable connecting joint, the elbow connecting member, the upper pressure cap of the elbow connecting member, and the lower pressure cap of the elbow connecting member are made of soluble aluminum-based alloy and have a controllable degradable rubber protective coating on their outer surfaces.

[0021] Preferably, the second sealing assembly includes a second rubber tube, an upper pressure cap for the second rubber tube, a lower pressure cap for the second rubber tube, an upper connector for the second rubber tube, and a central tube for the second rubber plug. Both ends of the second rubber tube are detachably connected to one end of the upper connector for the second rubber tube and one end of the lower pressure cap for the second rubber tube, respectively. The other ends of the upper connector for the second rubber tube and the lower pressure cap for the second rubber tube are detachably connected to one end of the upper pressure cap for the second rubber tube and the sealing guide assembly, respectively. The other end of the upper pressure cap for the second rubber tube is detachably connected to one end of the second movable connecting section relative to the elbow connector.

[0022] The upper and lower caps of the second rubber tube are hollow structures. The upper cap of the second rubber tube has a ball head groove on the inner wall of one end relative to the second rubber tube, which mates with the hollow ball head, and a female buckle on the other end. The lower cap of the second rubber tube has a male buckle and a female buckle on both ends, respectively.

[0023] The second rubber tube upper connector has the same structure as the first rubber tube upper connector and the first rubber tube lower connector, which is a trapezoidal hollow structure and each end is provided with a male buckle. The end of the second rubber tube upper connector relative to the second rubber tube is engaged with the end of the upper pressure cap of the second rubber tube relative to the ball head groove.

[0024] The second rubber tube has female buckles at both ends, which are respectively engaged with the male buckles of the upper connector of the second rubber tube relative to the upper cap of the second rubber tube and the lower cap of the second rubber tube. The middle part of the second rubber tube is configured as an expandable rubber tube, which includes an inner expandable rubber tube and an outer expandable rubber tube. The center tube of the second rubber plug is disposed inside the second rubber tube, with one end engaged with the upper connector of the second rubber tube and the other end detachably connected to the sealing guide assembly. The center tube of the second rubber plug is used to realize the pressure expansion of the inner expandable rubber tube and the outer expandable rubber tube of the second rubber tube. The center of the second rubber plug is provided with two or more sieve-shaped flow holes in the middle.

[0025] Preferably, the inner and outer expandable rubber layers of the second rubber sleeve are a composite structure of biodegradable rubber and soluble aluminum alloy. The outer surfaces of both layers are provided with a cold-sprayed rubber vulcanized layer that bonds TiN particles, ensuring that the second rubber sleeve, after expansion, can be firmly sealed within the wellbore cavity and, depending on the wellbore temperature and alkaline liquid conditions, degrades spontaneously within a set time.

[0026] The second rubber tube, the upper pressure cap of the second rubber tube, the lower pressure cap of the second rubber tube, the upper connector of the second rubber tube, and the central tube of the second rubber stopper are made of soluble aluminum-based alloy, which can be slowly dissolved in NaOH aqueous solution into micron-sized metal powder;

[0027] Preferably, the sealing and guiding assembly includes a shoe upper pressure cap, a shoe expandable plugging one-way valve, and a shoe guide cone. One end of the shoe upper pressure cap is detachably connected to one end of the shoe guide cone. The shoe expandable plugging one-way valve is disposed inside the shoe guide cone and is in unidirectional communication with the shoe upper pressure cap and the shoe guide cone.

[0028] The upper pressure cap and the guide cone of the shoe are hollow structures made of soluble aluminum alloy. Both ends of the upper pressure cap are provided with male buckles, and one end of the guide cone is provided with a female buckle that engages with one end of the upper pressure cap. The other end is tapered. The end of the upper pressure cap relative to the guide cone engages with the female buckle end of the lower pressure cap of the second rubber sleeve.

[0029] The guide cone has a first flow hole at its cone tip, and two or more second flow holes are provided on the side wall of the guide cone near the first flow hole.

[0030] The expandable plugging one-way valve includes a one-way valve conical plug, a rubber spring, and a metal gasket screen. The one-way valve conical plug, rubber spring, and metal gasket screen are combined using a rubber vulcanization process. The one-way valve conical plug and rubber spring are made of expandable rubber and have a soluble magnesium alloy protective layer on their outer surface. The metal gasket screen is made of a soluble aluminum-based alloy.

[0031] Preferably, the material of the sealing and detachment joint is low-carbon alloy steel, and the material of the release mechanism is soluble aluminum-based alloy.

[0032] On the other hand, the present invention also provides a method for using a biodegradable expandable temporary plugging device for wellbores, the specific steps of which are as follows:

[0033] Step 1: Connect the coiled tubing to the device via the trapezoidal female thread of the plugging disconnector, and use the coiled tubing to quickly lower the device to the well section to be plugged.

[0034] Step 2: Pump an appropriate amount of KCl or NaCl electrolyte into the continuous tubing to dissolve the magnesium alloy coating on the surface of the expandable blockage check valve of the guide shoe, and allow it to absorb water, expand, and block the flow passage inside the sealing guide assembly.

[0035] Step 3: Pump an appropriate amount of clean water into the continuous tubing to make the first and second sealing components expand and set, while the first rubber stopper check valve can no longer continue to expand and closes.

[0036] Step 4: Insert a soluble metal ball into the inner cavity of the coiled tubing. The soluble metal ball falls into the release semi-circular groove of the release mechanism to seal the flow passage of the device.

[0037] Step 5: Continue pumping clean water into the coiled tubing to increase the pump pressure of the fluid injected into the coiled tubing. When the pressure reaches the predetermined specification, the shear pin will cut off, thus separating the coiled tubing from the device to enable subsequent downhole operations.

[0038] Step 6: After the downhole construction is completed, inject an appropriate amount of NaOH aqueous solution into the well casing to dissolve the device inside the well, thus completing the entire construction process.

[0039] The advantages and positive effects of this invention are:

[0040] This invention provides a biodegradable expansion plugging device for wellbore and its usage method. The device is made of soluble and controllable degradable materials, including controllable dissolvable aluminum alloy and controllable degradable rubber. In actual operation, it can be used for tubing expansion plugging in highly deviated wells, dogleg sections, and horizontal wells. It has the advantages of high construction efficiency, strong wellbore applicability, safe release, and overall controllable degradation. After the operation, it will not cause any blockage in the wellbore and is not affected by wellbore bending deformation. It overcomes the technical problem of poor passage in well sections with large doglegs due to the excessive length of the rigid part of conventional tubing plugging construction tools. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the overall structure of the biodegradable expansion temporary plugging device for wellbore of the present invention;

[0042] Figure 2 This is a schematic diagram of the structure of the sealing and detachment assembly of the present invention;

[0043] Figure 3 This is a schematic diagram of the structure of the first sealing component of the present invention;

[0044] Figure 4 This is a schematic diagram of the structure of the flexible connection component of the present invention;

[0045] Figure 5 This is a schematic diagram of the structure of the second sealing component of the present invention;

[0046] Figure 6 This is a schematic diagram of the structure of the blocking and guiding component of the present invention;

[0047] Figure 7 This is a flowchart illustrating the method of using the biodegradable expansion temporary plugging device for wellbore according to the present invention.

[0048] Among them, 1. Sealing and detaching upper joint; 2. Shearing pin; 3. Release; 4. First rubber tube upper pressure cap; 5. First rubber tube upper joint; 6. First rubber stopper check valve; 7. First rubber stopper center tube; 8. First rubber tube inner expandable rubber tube; 9. First rubber tube; 10. First rubber tube outer expandable rubber tube assembly; 12. First rubber tube lower joint; 13. First rubber tube lower pressure cap; 14. First movable connecting section; 15. Elbow joint connecting piece upper pressure cap; 16. Elbow joint connecting piece; 17. Elbow joint connecting piece lower pressure cap; 18. Second movable connecting section; 19. Second rubber tube upper pressure cap; 20. Second rubber tube upper joint; 21. Second rubber stopper center tube; 2 2. Inner expandable rubber tube of the second rubber tube; 23. Second rubber tube; 24. Outer expandable rubber tube of the second rubber tube; 26. Lower pressure cap of the second rubber tube; 27. Upper pressure cap of the guide shoe; 28. Expandable blockage check valve of the guide shoe; 29. ​​Guide shoe guide cone; 301. Release semi-circular groove; 302. First release sealing ring groove; 303. Second release sealing ring groove; 401. Sealing ring groove of the upper pressure cap of the first rubber tube; 402. Sealing ring groove of the upper pressure cap of the second rubber tube; 1301. Sealing ring groove of the lower pressure cap of the second rubber tube; 1302. Sealing ring groove of the lower pressure cap of the second rubber tube; 2801. Conical plug of the check valve; 2802. Rubber spring; 2803. Metal gasket screen. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings.

[0050] This invention proposes a biodegradable, expandable temporary plugging device for wellbores, such as... Figure 1 As shown, the device includes a plugging and detachment assembly, a first plugging assembly, a flexible connection assembly, a second plugging assembly, and a plugging guide assembly. One end of the plugging and detachment assembly is detachably connected to the coiled tubing, and the other end is detachably connected to one end of the first plugging assembly. The other end of the first plugging assembly is detachably connected to one end of the flexible connection assembly, the other end of the flexible connection assembly is detachably connected to one end of the second plugging assembly, and the other end of the second plugging assembly is detachably connected to one end of the plugging guide assembly. The plugging and detachment assembly, the first plugging assembly, the flexible connection assembly, the second plugging assembly, and the plugging guide assembly are interconnected. The plugging and detachment assembly is used to separate the coiled tubing connector from the biodegradable expandable temporary plugging device. The first and second plugging assemblies are used to set the well section. The plugging guide assembly is used to quickly lower the biodegradable expandable temporary plugging device to the well section to be plugged.

[0051] In this embodiment, as Figure 2As shown, the sealing and detachment assembly includes a sealing and detachment upper connector 1, a shear pin 2, and a release handle 3. One end of the release handle 3 is fitted inside one end of the sealing and detachment upper connector 1 and engages with the shear pin 2. The shear pin 2 is used to separate the release handle 3 from the sealing and detachment upper connector 1. The sealing and detachment upper connector 1 has a hollow structure with a trapezoidal female buckle on the inner wall of one end and a sealing and detachment upper connector mounting hole on the side wall of the other end.

[0052] The dropper 3 has a hollow structure with a dropper semicircular groove 301 on the inner wall of one end and a hollow ball head on the outer wall of the other end. The dropper 3 has a dropper mounting hole, a first dropper sealing ring groove 302 and a second dropper sealing ring groove 303 on the outer wall near the dropper semicircular groove 301. The shear pin 2 is connected to the sealing and detachment upper connector 1 and the dropper 3 through the sealing and detachment upper connector mounting hole and the liquid dropper mounting hole, respectively.

[0053] In this embodiment, as Figure 3 As shown, the first sealing assembly includes a first rubber tube 9, a first rubber tube upper pressure cap 4, a first rubber tube lower pressure cap 13, a first rubber tube upper connector 5, a first rubber tube lower connector 12, a first rubber stopper check valve 6, and a first rubber stopper center tube 7. Both ends of the first rubber tube 9 are detachably connected to one end of the first rubber tube upper connector 5 and the first rubber tube lower connector 12, respectively. The other ends of the first rubber tube upper connector 5 and the first rubber tube lower connector 12 are detachably connected to one end of the first rubber tube upper pressure cap 4 and the first rubber tube lower pressure cap 13, respectively. The other end of the first rubber tube upper pressure cap 4 is detachably connected to one end of the release handle 3 relative to the release handle semicircular groove 301. The other end of the first rubber tube lower pressure cap 13 is detachably connected to the flexible connection assembly.

[0054] The upper pressure cap 4 and the lower pressure cap 13 of the first rubber tube have the same structure, which is a hollow structure. One end of the inner wall of the first rubber tube 9 has a ball head groove that mates with the hollow ball head, and the other end has a female buckle.

[0055] The first rubber tube upper connector 5 and the first rubber tube lower connector 12 have the same trapezoidal hollow structure and are respectively provided with male buckles at both ends. The ends of the first rubber tube upper connector 5 and the first rubber tube lower connector 12 relative to the first rubber tube 9 are respectively engaged with the ends of the first rubber tube upper pressure cap 4 and the first rubber tube lower pressure cap 13 relative to the ball head groove. The first rubber stopper one-way valve 6 is disposed inside the first rubber tube upper connector 5. The first rubber stopper one-way valve 6 is used for one-way communication between the sealing and dislodging assembly and the first sealing assembly.

[0056] The first rubber tube 9 has female fasteners at both ends, which are respectively engaged with the upper connector 5 and the lower connector 12 of the first rubber tube relative to one end of the upper pressure cap 4 and the lower pressure cap 13 of the first rubber tube. The middle part of the first rubber tube 9 is configured as an expandable rubber tube, which includes an inner expandable rubber tube 8 and an outer expandable rubber tube 10. The first rubber stopper center tube 7 is disposed inside the first rubber tube 9 and its two ends are respectively engaged with the upper connector 5 and the lower connector 12 of the first rubber tube. The first rubber stopper center tube 7 is used to realize the pressure expansion of the inner expandable rubber tube 8 and the outer expandable rubber tube 10 of the first rubber tube. The middle part of the first rubber stopper center tube 7 is provided with two or more sieve-shaped flow holes.

[0057] The first rubber stopper flow valve 6 includes a flow valve conical stopper 2801, a rubber spring 2802, and a metal gasket screen 2803. The flow valve conical stopper 2801, the rubber spring 2802, and the metal gasket screen 2803 are combined using a rubber vulcanization process. The flow valve conical stopper 2801 and the rubber spring 2802 are made of expanded rubber and have a soluble magnesium alloy protective layer on their outer surface. The metal gasket screen 2803 is made of a soluble aluminum-based alloy.

[0058] The inner wall of the first rubber tube upper pressure cap 4 is provided with a first rubber tube upper pressure cap sealing ring groove 401 and a first rubber tube upper pressure cap sealing ring groove 402 near the ball head groove. The inner wall of the first rubber tube lower pressure cap 13 is provided with a first rubber tube lower pressure cap sealing ring groove 1301 and a first rubber tube lower pressure cap sealing ring groove 1302 near the ball head groove.

[0059] In this embodiment, the inner expandable rubber sleeve 8 and the outer expandable rubber sleeve 10 of the first rubber sleeve are a composite structure of biodegradable rubber and soluble aluminum alloy. The outer surfaces of the inner expandable rubber sleeve 8 and the outer expandable rubber sleeve 10 are provided with a cold-sprayed rubber vulcanized layer that bonds TiN particles. This allows the first rubber sleeve to be firmly sealed within the wellbore cavity after expansion and to self-degrade within a predetermined time depending on the wellbore temperature and alkaline liquid conditions.

[0060] The first rubber tube 9, the first rubber tube upper pressure cap 4, the first rubber tube lower pressure cap 13, the first rubber tube upper connector 5, the first rubber tube lower connector 12, the first rubber stopper check valve 6, and the first rubber stopper center tube 7 are made of a soluble aluminum-based alloy, which can be slowly dissolved in NaOH aqueous solution into micron-sized metal powder.

[0061] In this embodiment, as Figure 4As shown, the flexible connection assembly includes a first movable connecting section 14, a second movable connecting section 18, an elbow connector 16, an upper pressure cap 15 for the elbow connector, and a lower pressure cap 17 for the elbow connector. The first movable connecting section 14, the second movable connecting section 18, the elbow connector 16, the upper pressure cap 15 for the elbow connector, and the lower pressure cap 17 for the elbow connector are detachably connected and communicate with each other.

[0062] The toggle connector 16 is a hollow tubular structure with male buckles at both ends. The upper pressure cap 15 and lower pressure cap 17 of the toggle connector have the same hollow tubular structure, with a female buckle at one end and a ball head groove on the inner wall of the other end. The first movable connecting section 14 and the second movable connecting section 18 have the same hollow tubular structure, with hollow ball heads at both ends that mate with the ball head grooves. The upper pressure cap 15 and lower pressure cap 17 of the toggle connector have their female buckles engaged with the toggle connector 16 at one end and engaged with the first movable connecting section 14 and the second movable connecting section 18 at the other end.

[0063] The first movable connecting section 14, the second movable connecting section 18, the elbow connecting member 16, the upper pressure cap 15 of the elbow connecting member, and the lower pressure cap 17 of the elbow connecting member are made of soluble aluminum-based alloy and have a controllable degradable rubber protective coating on their outer surfaces.

[0064] In use, the first movable connecting section 14 and the second movable connecting section 18 can be extended as needed. The tubular separation in the middle of the same movable connecting section is respectively provided with internal threads and external threads.

[0065] In this embodiment, as Figure 5 As shown, the second sealing assembly includes a second rubber tube 23, a second rubber tube upper pressure cap 19, a second rubber tube lower pressure cap 26, a second rubber tube upper connector 20, and a second rubber stopper center tube 21. Both ends of the second rubber tube 23 are detachably connected to one end of the second rubber tube upper connector 20 and the second rubber tube lower pressure cap 26, respectively. The other ends of the second rubber tube upper connector 20 and the second rubber tube lower pressure cap 26 are detachably connected to one end of the second rubber tube upper pressure cap 19 and the sealing guide assembly, respectively. The other end of the second rubber tube upper pressure cap 19 is detachably connected to one end of the second movable connecting joint 18 relative to the elbow connector 16.

[0066] The upper pressure cap 19 and the lower pressure cap 26 of the second rubber tube are hollow structures. The inner wall of the upper pressure cap 19 of the second rubber tube at one end relative to the second rubber tube 23 is provided with a ball head groove that mates with the hollow ball head, and the other end is provided with a female buckle. The two ends of the lower pressure cap 26 of the second rubber tube are respectively provided with a male buckle and a female buckle.

[0067] The second rubber tube upper connector 20, the first rubber tube upper connector 5, and the first rubber tube lower connector 12 have the same structure, which is a trapezoidal hollow structure and both ends are provided with male buckles. The end of the second rubber tube upper connector 20 relative to the second rubber tube 23 is engaged with the end of the second rubber tube upper pressure cap 19 relative to the ball head groove.

[0068] The second rubber tube 23 has female snap-fits at both ends, which respectively engage with the male snap-fit ​​ends of the upper connector 20 of the second rubber tube relative to the upper pressure cap 19 of the second rubber tube and the lower pressure cap 26 of the second rubber tube. The middle part of the second rubber tube 23 is configured as an expandable rubber tube, which includes an inner expandable rubber tube 22 and an outer expandable rubber tube 24. The second rubber stopper center tube 21 is disposed inside the second rubber tube 23, with one end engaged with the upper connector 20 of the second rubber tube and the other end detachably connected to the sealing guide assembly. The second rubber stopper center tube 21 is used to pressurize and expand the inner expandable rubber tube 22 and the outer expandable rubber tube 24 of the second rubber tube. The middle part of the second rubber stopper center tube 21 is provided with two or more sieve-shaped flow holes.

[0069] In this embodiment, the inner expandable rubber sleeve 22 and the outer expandable rubber sleeve 24 of the second rubber sleeve are a composite structure of biodegradable rubber and soluble aluminum alloy. The outer surfaces of the inner and outer expandable rubber sleeves are provided with a cold-sprayed rubber vulcanized layer that bonds TiN particles, so that after the second rubber sleeve 23 expands, it can be firmly sealed in the wellbore cavity and, depending on the wellbore temperature and alkaline liquid conditions, will self-degrade within a predetermined time.

[0070] The second rubber tube 23, the upper pressure cap 19 of the second rubber tube, the lower pressure cap 26 of the second rubber tube, the upper connector 20 of the second rubber tube, and the central tube 21 of the second rubber stopper are made of a soluble aluminum-based alloy, which can be slowly dissolved in NaOH aqueous solution into micron-sized metal powder.

[0071] In this embodiment, as Figure 6 As shown, the sealing and guiding assembly includes a shoe upper pressure cap 27, a shoe expandable blocking one-way valve 28, and a shoe guide cone 29. One end of the shoe upper pressure cap 27 is detachably connected to one end of the shoe guide cone 29. The shoe expandable blocking one-way valve 28 is disposed inside the shoe guide cone 29 and is in unidirectional communication with the shoe upper pressure cap 27 and the shoe guide cone 29.

[0072] The upper pressure cap 27 and the guide cone 29 of the shoe guide are hollow structures made of soluble aluminum alloy. Both ends of the upper pressure cap 27 are provided with male buckles. One end of the guide cone 29 is provided with a female buckle that engages with one end of the upper pressure cap 27, and the other end is conical. The end of the upper pressure cap 27 relative to the guide cone 29 engages with the female buckle end of the lower pressure cap 26 of the second rubber sleeve.

[0073] The shoe guide cone 29 has a first flow hole at its cone tip, and two or more second flow holes are provided on the side wall of the shoe guide cone 29 near the first flow hole.

[0074] The expandable plugging one-way valve 28 includes a one-way valve conical plug 2801, a rubber spring 2802, and a metal gasket screen 2803. The one-way valve conical plug 2801, the rubber spring 2802, and the metal gasket screen 2803 are combined using a rubber vulcanization process. The one-way valve conical plug 2801 and the rubber spring 2802 are made of expandable rubber and have a soluble magnesium alloy protective layer on their outer surface. The metal gasket screen 2803 is made of a soluble aluminum-based alloy.

[0075] In this embodiment, the material of the sealing and detachment connector 1 is low-carbon alloy steel, and the material of the release handle 3 is soluble aluminum-based alloy.

[0076] This invention also proposes a method for using a biodegradable expansion temporary plugging device for wellbores, the specific steps of which are as follows:

[0077] Step 1: Connect the coiled tubing to the device through the trapezoidal female thread of the sealing disconnector 1, and use the coiled tubing to quickly lower the device to the well section to be sealed.

[0078] Step 2: Pump an appropriate amount of KCl or NaCl electrolyte into the continuous tubing to dissolve the magnesium alloy coating on the surface of the expandable blockage check valve 28 of the guide shoe, and allow it to absorb water, expand, and block the flow passage inside the sealing guide assembly.

[0079] Step 3: Pump an appropriate amount of clean water into the continuous tubing to make the first and second sealing components expand and set, while the first rubber stopper check valve 6 can no longer continue to expand and is closed.

[0080] Step 4: Insert a soluble metal ball into the inner cavity of the coiled tubing. The soluble metal ball falls into the release semicircular groove 301 of the release 3 to seal the flow passage of this device.

[0081] Step 5: Continue pumping clean water into the coiled tubing to increase the pump pressure of the fluid injected into the coiled tubing. When the pressure reaches the predetermined specification, the shear pin 2 will cut off, thereby separating the coiled tubing from the device to enable subsequent downhole operations.

[0082] Step 6: After the downhole construction is completed, inject an appropriate amount of NaOH aqueous solution into the well casing to dissolve the device inside the well, thus completing the entire construction process.

[0083] Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0084] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0085] In summary, the content of this invention is not limited to the above-described embodiments. Those skilled in the art can propose other embodiments within the technical guiding principles of this invention, but these embodiments are all included within the scope of this invention.

[0086] It should be emphasized that the embodiments described in this invention are illustrative rather than limiting. Therefore, this invention includes, but is not limited to, the embodiments described in the specific implementation. Any other implementations derived by those skilled in the art based on the technical solutions of this invention are also within the scope of protection of this invention.

Claims

1. A biodegradable expandable temporary plugging device for wellbores, characterized in that: The device includes a plugging and detachment assembly, a first plugging assembly, a flexible connection assembly, a second plugging assembly, and a plugging guide assembly. One end of the plugging and detachment assembly is detachably connected to the coiled tubing, and the other end is detachably connected to one end of the first plugging assembly. The other end of the first plugging assembly is detachably connected to one end of the flexible connection assembly, the other end of the flexible connection assembly is detachably connected to one end of the second plugging assembly, and the other end of the second plugging assembly is detachably connected to one end of the plugging guide assembly. The plugging and detachment assembly, the first plugging assembly, the flexible connection assembly, the second plugging assembly, and the plugging guide assembly are interconnected. The plugging and detachment assembly is used to separate the coiled tubing connector from the biodegradable expandable temporary plugging device. The first and second plugging assemblies are used to set the well section. The plugging guide assembly is used to quickly lower the biodegradable expandable temporary plugging device into the well section to be plugged. The sealing and detachment assembly includes a sealing and detachment upper connector, a shear pin, and a release handle. One end of the release handle is fitted inside one end of the sealing and detachment upper connector and engages with the shear pin. The shear pin is used to separate the release handle from the sealing and detachment upper connector. The sealing and detachment upper connector has a hollow structure with a trapezoidal female buckle on the inner wall of one end and a sealing and detachment upper connector mounting hole on the side wall of the other end. The dropper is a hollow structure with a semi-circular groove on the inner wall of one end and a hollow ball head on the outer wall of the other end. The outer wall of the dropper has a dropper mounting hole, a first dropper sealing ring groove and a second dropper sealing ring groove near the semi-circular groove. The shear pin is connected to the sealing and detachment upper connector and the dropper through the sealing and detachment upper connector mounting hole and the dropper mounting hole, respectively. The first sealing assembly includes a first rubber tube, a first rubber tube upper pressure cap, a first rubber tube lower pressure cap, a first rubber tube upper connector, a first rubber tube lower connector, a first rubber stopper check valve, and a first rubber stopper center tube. Both ends of the first rubber tube are detachably connected to one end of the first rubber tube upper connector and one end of the first rubber tube lower connector, respectively. The other ends of the first rubber tube upper connector and the first rubber tube lower connector are detachably connected to one end of the first rubber tube upper pressure cap and one end of the first rubber tube lower pressure cap, respectively. The other end of the first rubber tube upper pressure cap is detachably connected to one end of the release mechanism relative to the release mechanism semicircular groove. The other end of the first rubber tube lower pressure cap is detachably connected to the flexible connection assembly. The upper and lower pressure caps of the first rubber tube have the same hollow structure, and a ball head groove that mates with the hollow ball head is provided on the inner wall of one end of the first rubber tube, while a female buckle is provided on the other end. The upper and lower connectors of the first rubber tube have the same trapezoidal hollow structure, with male snap-fits at both ends. The ends of the upper and lower connectors relative to the first rubber tube respectively engage with the upper and lower pressure caps of the first rubber tube relative to the ball head groove. The first rubber stopper check valve is located inside the upper connector of the first rubber tube, and serves as a one-way connection between the sealing / dislodging assembly and the first sealing assembly. The first rubber tube has female buckles at both ends, which respectively engage with one end of the upper and lower connectors of the first rubber tube relative to the upper and lower pressure caps of the first rubber tube. The middle part of the first rubber tube is configured as an expandable rubber tube, comprising an inner expandable rubber tube and an outer expandable rubber tube. The central tube of the first rubber stopper is disposed inside the first rubber tube, and its two ends are respectively engaged with the upper and lower connectors of the first rubber tube. The central tube of the first rubber stopper is used to pressurize and expand the inner and outer expandable rubber tubes of the first rubber tube. The central tube of the first rubber stopper has two or more sieve-shaped flow holes in its middle section. The first rubber stopper flow valve includes a flow valve conical stopper, a rubber spring, and a metal gasket screen. The flow valve conical stopper, the rubber spring, and the metal gasket screen are combined using a rubber vulcanization process. The flow valve conical stopper and the rubber spring are made of expanded rubber and have a soluble magnesium alloy protective layer on their outer surface. The metal gasket screen is made of a soluble aluminum-based alloy. The inner wall of the first rubber tube upper pressure cap near the ball head groove is provided with a first rubber tube upper pressure cap sealing ring groove and a second rubber tube upper pressure cap sealing ring groove, respectively. The inner wall of the first rubber tube lower pressure cap near the ball head groove is provided with a first rubber tube lower pressure cap sealing ring groove and a second rubber tube lower pressure cap sealing ring groove, respectively.

2. The biodegradable expansion temporary plugging device for wellbore as described in claim 1, characterized in that: The inner and outer expandable rubber sleeves of the first rubber sleeve are composite structures of biodegradable rubber and soluble aluminum alloy. The outer surfaces of both the inner and outer expandable rubber sleeves are provided with a cold-sprayed rubber vulcanized layer that bonds TiN particles. This allows the first rubber sleeve to be firmly sealed within the wellbore cavity after expansion and to self-degrade within a predetermined time, depending on the wellbore temperature and alkaline liquid conditions. The first rubber tube, the upper pressure cap of the first rubber tube, the lower pressure cap of the first rubber tube, the upper connector of the first rubber tube, the lower connector of the first rubber tube, the one-way valve of the first rubber stopper, and the central tube of the first rubber stopper are made of soluble aluminum-based alloy, which can be slowly dissolved in NaOH aqueous solution into micron-sized metal powder.

3. The biodegradable expansion temporary plugging device for wellbores according to claim 1, characterized in that: The flexible connection assembly includes a first movable connecting section, a second movable connecting section, an elbow connector, an upper pressure cap for the elbow connector, and a lower pressure cap for the elbow connector. The first movable connecting section, the second movable connecting section, the elbow connector, the upper pressure cap for the elbow connector, and the lower pressure cap for the elbow connector are detachably connected to each other and are in communication. The toggle connector is a hollow tubular structure with male buckles at both ends. The upper and lower pressure caps of the toggle connector have the same hollow tubular structure, with a female buckle at one end and a ball joint groove on the inner wall of the other end. The first and second movable connecting sections have the same hollow tubular structure, with hollow ball joints at both ends that mate with the ball joint grooves. The upper and lower pressure caps of the toggle connector have female buckles at one end that engages with the toggle connector, and the other end engages with the first and second movable connecting sections. The first movable connecting joint, the second movable connecting joint, the elbow connecting member, the upper pressure cap of the elbow connecting member, and the lower pressure cap of the elbow connecting member are made of soluble aluminum-based alloy and have a controllable degradable rubber protective coating on their outer surfaces.

4. The biodegradable expansion temporary plugging device for wellbore according to claim 3, characterized in that: The second sealing assembly includes a second rubber tube, an upper pressure cap for the second rubber tube, a lower pressure cap for the second rubber tube, an upper connector for the second rubber tube, and a central tube for the second rubber stopper. Both ends of the second rubber tube are detachably connected to one end of the upper connector for the second rubber tube and one end of the lower pressure cap for the second rubber tube, respectively. The other ends of the upper connector for the second rubber tube and the lower pressure cap for the second rubber tube are detachably connected to one end of the upper pressure cap for the second rubber tube and the sealing guide assembly, respectively. The other end of the upper pressure cap for the second rubber tube is detachably connected to one end of the second movable connecting section relative to the elbow connector. The upper and lower caps of the second rubber tube are hollow structures. The upper cap of the second rubber tube has a ball head groove on the inner wall of one end relative to the second rubber tube, which mates with the hollow ball head, and a female buckle on the other end. The lower cap of the second rubber tube has a male buckle and a female buckle on both ends, respectively. The second rubber tube upper connector has the same structure as the first rubber tube upper connector and the first rubber tube lower connector, which is a trapezoidal hollow structure and each end is provided with a male buckle. The end of the second rubber tube upper connector relative to the second rubber tube is engaged with the end of the upper pressure cap of the second rubber tube relative to the ball head groove. The second rubber tube has female buckles at both ends, which are respectively engaged with the male buckles of the upper connector of the second rubber tube relative to the upper cap of the second rubber tube and the lower cap of the second rubber tube. The middle part of the second rubber tube is configured as an expandable rubber tube, which includes an inner expandable rubber tube and an outer expandable rubber tube. The central tube of the second rubber stopper is disposed inside the second rubber tube, with one end engaged with the upper connector of the second rubber tube and the other end detachably connected to the sealing and guiding assembly. The central tube of the second rubber stopper is used to realize the pressure expansion of the inner expandable rubber tube and the outer expandable rubber tube of the second rubber tube. The central part of the central tube of the second rubber stopper is provided with two or more sieve-shaped flow holes.

5. The biodegradable expansion temporary plugging device for wellbore according to claim 4, characterized in that: The inner and outer expandable rubber layers of the second rubber sleeve are composite structures of biodegradable rubber and soluble aluminum alloy. The outer surfaces of both layers are provided with a cold-sprayed, bonded TiN particle rubber vulcanized layer. This ensures that the second rubber sleeve, after expansion, can be firmly sealed within the wellbore cavity and will self-degrade within a set time depending on the wellbore temperature and alkaline liquid conditions. The second rubber tube, the upper pressure cap of the second rubber tube, the lower pressure cap of the second rubber tube, the upper connector of the second rubber tube, and the central tube of the second rubber stopper are made of a soluble aluminum-based alloy, which can be slowly dissolved in NaOH aqueous solution into micron-sized metal powder.

6. The biodegradable expansion temporary plugging device for wellbore according to claim 4, characterized in that: The sealing and guiding assembly includes a shoe upper pressure cap, a shoe expandable plugging one-way valve, and a shoe guide cone. One end of the shoe upper pressure cap is detachably connected to one end of the shoe guide cone. The shoe expandable plugging one-way valve is disposed inside the shoe guide cone and is in unidirectional communication with the shoe upper pressure cap and the shoe guide cone. The upper pressure cap and the guide cone of the shoe are hollow structures made of soluble aluminum alloy. Both ends of the upper pressure cap are provided with male buckles, and one end of the guide cone is provided with a female buckle that engages with one end of the upper pressure cap. The other end is tapered. The end of the upper pressure cap relative to the guide cone engages with the female buckle end of the lower pressure cap of the second rubber sleeve. The guide cone has a first flow hole at its cone tip, and two or more second flow holes are provided on the side wall of the guide cone near the first flow hole. The expandable plugging one-way valve includes a one-way valve cone plug, a rubber spring, and a metal gasket screen. The one-way valve cone plug, rubber spring, and metal gasket screen are combined using a rubber vulcanization process. The one-way valve cone plug and rubber spring are made of expandable rubber and have a soluble magnesium alloy protective layer on their outer surface. The metal gasket screen is made of a soluble aluminum-based alloy.

7. The biodegradable expansion temporary plugging device for wellbore according to claim 1, characterized in that: The material of the sealing and detachment joint is low-carbon alloy steel, and the material of the dropper is soluble aluminum-based alloy.

8. The method of using the biodegradable expansion temporary plugging device for wellbore according to claim 6, characterized in that: The specific steps are as follows: Step 1: Connect the coiled tubing to the device via the trapezoidal female thread of the plugging disconnector, and use the coiled tubing to quickly lower the device to the well section to be plugged. Step 2: Pump an appropriate amount of KCl or NaCl electrolyte into the continuous tubing to dissolve the magnesium alloy coating on the surface of the expandable blockage check valve of the guide shoe, and allow it to absorb water, expand, and block the flow passage inside the sealing guide assembly. Step 3: Pump an appropriate amount of clean water into the continuous tubing to make the first and second sealing components expand and set, while the first rubber stopper check valve can no longer continue to expand and closes. Step 4: Insert a soluble metal ball into the inner cavity of the coiled tubing. The soluble metal ball falls into the release semi-circular groove of the release mechanism to seal the flow passage of the device. Step 5: Continue pumping clean water into the coiled tubing to increase the pump pressure of the fluid injected into the coiled tubing. When the pressure reaches the predetermined specification, the shear pin will cut off, thus separating the coiled tubing from the device to enable subsequent downhole operations. Step 6: After the downhole construction is completed, inject an appropriate amount of NaOH aqueous solution into the well casing to dissolve the device inside the well, thus completing the entire construction process.

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