Annular sealing device and method

Abstract

The invention belongs to the technical field of downhole tools, and particularly relates to an annulus sealing device and an annulus sealing method. The annulus sealing device includes: a central tube; the piston is arranged on the outer side of the central pipe; the supporting sleeve is arranged on the outer side of the central pipe and located below the piston, and the supporting sleeve is configured to make contact with underground liquid and can be expanded automatically; the outer cylinder assembly is arranged on the outer side of the supporting sleeve; the piston is constructed to be capable of moving downwards under pressure and stretching into the position between the supporting sleeve and the center pipe, so that the supporting sleeve and the outer barrel assembly expand in the radial direction, and the supporting sleeve continues to expand after making contact with underground liquid.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of downhole tools, and particularly relates to an annulus sealing device and an annulus sealing method. BACKGROUND

[0002] In recent years, with the vigorous development of unconventional oil and gas resources, in order to improve the production of oil and gas, well types such as deep wells, ultra-deep wells, high-deviation wells, and long horizontal wells gradually increase. The packer is a key downhole tool for oil and gas field development, mainly used for implementing processes such as separate layer acidizing, separate layer fracturing, separate layer water injection, separate layer gas production, and separate layer testing. With the increase of well depth, complex working conditions such as high temperature, high pressure, and high hydrogen sulfide content bring more severe service conditions to the packer.

[0003] After hydraulic fracturing, low-permeability oil and gas reservoirs, especially shale gas wells, are prone to fracture closure during later oil and gas production, resulting in a decrease in production. Repeated fracturing is one of the effective ways to improve the production of oil and gas wells and prolong the life of oil and gas wells. When implementing repeated fracturing, the annulus between the pipe string and the well wall must be sealed. The conventional method is to use the existing packer to seal the annulus between the pipe string and the well wall, and then through repeated fracturing, new production layer hydraulic fracturing modification can be carried out under the same wellbore conditions to obtain oil and gas production. However, due to the size limitation of the existing wellbore, the expansion degree of the conventional packer is too low, and the pressure bearing after setting is small, which makes it difficult to achieve large displacement large-scale repeated fracturing.

[0004] In view of the deficiencies of the prior art, the present application provides an annulus sealing device. SUMMARY

[0005] In view of the above technical problems, the present application aims to provide an annulus sealing device which can strengthen the sealing between the wellbore and the pipe string, thereby adapting to large-size wellbores.

[0006] The present application also provides an annulus sealing method, which uses the annulus sealing device according to the present application and can seal between a large-size wellbore and a pipe string.

[0007] According to the present application, an annulus sealing device is provided, comprising: a center pipe; a piston arranged outside the center pipe; a support sleeve arranged outside the center pipe and below the piston, the support sleeve being configured to be self-expandable by contacting downhole liquid; and an outer cylinder assembly arranged outside the support sleeve; the piston is configured to be downwardly movable under pressure and extend into between the support sleeve and the center pipe, thereby causing the support sleeve and the outer cylinder assembly to radially expand, and the support sleeve continues to expand after contacting the downhole liquid.

[0008] In one specific embodiment, the outer cylinder assembly is coaxially arranged outside the central pipe, forming an annular space between the outer cylinder assembly and the central pipe, and the piston and the support sleeve are arranged in the annular space, and a pressure transmission hole is arranged on the side wall of the central pipe and communicates with the upper end surface of the piston.

[0009] In one specific embodiment, in the initial state, the annular space where the support sleeve is located is in a sealed state, and in the setting state, the annular space where the support sleeve is located is in an open state, so that the downhole liquid can contact the support sleeve.

[0010] In one specific embodiment, the outer cylinder assembly comprises: a sealing sleeve coaxially sleeved outside the support sleeve, the lower end of the sealing sleeve exceeds the support sleeve and is sealingly connected with the central pipe; a fixed sleeve coaxially sleeved outside the piston, the upper end of the fixed sleeve exceeds the piston and is sealingly connected with the central pipe; in the initial state, the lower end of the fixed sleeve is sealingly connected with the upper end of the sealing sleeve, so that the annular space where the support sleeve is located is in a sealed state; in the setting state, the support sleeve pushes the upper end of the sealing sleeve to radially expand, so that the fixed sleeve and the sealing sleeve are unsealed, and in turn the annular space where the support sleeve is located is in an open state.

[0011] In one specific embodiment, a pin hole is arranged on the fixed sleeve, the piston is fixedly connected with the fixed sleeve through a shear pin, in the initial state, the piston closes the pin hole, and in the setting state, the piston moves relative to the pin hole to make the pin hole communicate with the pressure transmission hole.

[0012] In one specific embodiment, the upper end surface of the sealing sleeve axially abuts against the lower end surface of the fixed sleeve, and a sealing element is arranged between the upper end surface of the sealing sleeve and the lower end surface of the fixed sleeve.

[0013] In one specific embodiment, the sealing sleeve comprises: a support cylinder, the lower part of the support cylinder is sealingly connected with the central pipe; an expansion sealing sleeve coaxially arranged on the upper end of the support cylinder, the expansion sealing sleeve is coaxially sleeved outside the support sleeve; and a rubber sealing sleeve coaxially arranged outside the expansion sealing sleeve.

[0014] In one specific embodiment, the upper end of the support sleeve is configured in a shape that the inner diameter gradually decreases from top to bottom, and the lower end of the piston is configured in a shape that the outer diameter gradually decreases from top to bottom.

[0015] In one specific embodiment, a wedge-shaped sleeve is arranged outside the central pipe, the wedge-shaped sleeve is arranged below the support sleeve, the upper end of the wedge-shaped sleeve is configured in a shape gradually increasing in outer diameter from top to bottom, and the lower end of the support sleeve is configured in a shape gradually increasing in inner diameter from top to bottom.

[0016] According to the application, an annular sealing method is also provided, which uses the annular sealing device according to the application to perform annular sealing.

[0017] Compared with the prior art, the application has the following advantages.

[0018] The annular sealing device provided by the application comprises a central pipe, a piston and a support sleeve arranged outside the central pipe, and an outer cylinder assembly arranged outside the piston and the support sleeve. In the working process, the annular sealing device is connected in series on a pipe string and enters a well together with the pipe string. After the annular sealing device is lowered to a predetermined position in the wellbore, the piston is moved downward and extends into the space between the support sleeve and the central pipe by means of pressurizing the inside of the central pipe, so that the support sleeve is radially expanded, and then the support sleeve pushes the outer cylinder assembly to be radially expanded to seal with the inner wall of the wellbore, and the setting is completed.

[0019] The annular space is formed between the central pipe and the outer cylinder assembly of the application, and the support sleeve made of water-swellable material is arranged in the annular space. The annular space can keep the support sleeve in a sealed environment during the process of entering the well, so as to prevent the support sleeve from contacting with the liquid in the well. After the setting is completed, the annular space is unsealed, so that the liquid downhole can contact with the support sleeve, so that the support sleeve is expanded again, and the outer cylinder assembly is further pushed radially outward, so that the seal between the outer wall of the outer cylinder assembly and the wellbore is more tight.

[0020] The outer cylinder assembly of the application comprises an expansion sealing sleeve, and a rubber sealing sleeve is arranged outside the expansion sealing sleeve. The support sleeve pushes the expansion sealing sleeve to be radially expanded in the process of radial expansion, the setting is completed, and the rubber sealing sleeve can enhance the sealing effect. The expansion sealing sleeve is made of metal material, and the rubber sealing sleeve and the expansion sealing sleeve form a composite structure. Even in a high-temperature environment of 150 degrees Celsius, the rubber sealing sleeve will not cause the sealing failure caused by insufficient strength of the rubber material in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0021] The application will be described below with reference to the accompanying drawings.

[0022] Figure 1 An initial state schematic view of one embodiment of the annular sealing device according to the application after entering the well is shown;

[0023] Figure 2 An enlarged schematic view of part A in Figure 1 is shown;

[0024] Figure 3 An enlarged schematic view of part B in Figure 2 is shown.

[0025] Figure 4 A set state schematic view of the annular sealing device according to the present application is shown.

[0026] In the drawings:

[0027] 1, central pipe; 11, pressure transmission hole;

[0028] 2, piston;

[0029] 3, support sleeve;

[0030] 4, outer cylinder assembly; 41, sealing sleeve; 411, support cylinder; 412, expansion sealing sleeve; 413, rubber sealing sleeve; 414, abutting cylinder; 42, fixed sleeve; 421, pin hole; 422, shear pin;

[0031] 5, annular space;

[0032] 6, wedge sleeve;

[0033] 7, lower joint;

[0034] 81, first sealing ring; 82, second sealing ring; 83, third sealing ring; 84, fourth sealing ring; 85, fifth sealing ring;

[0035] 10, wellbore;

[0036] 100, annular sealing device.

[0037] In the present application, all the drawings are schematic drawings, which are only used to illustrate the principles of the present application, and are not drawn according to the actual proportions. DETAILED DESCRIPTION

[0038] The present application will be described below with reference to the drawings.

[0039] It should be noted that in the present application, the direction close to the wellhead after the annular sealing device according to the present application is put into the well is described as "upper end", "front end" or similar terms, i.e. Figure 1 above; the direction away from the wellhead after the annular sealing device according to the present application is put into the well is described as "lower end", "rear end" or similar terms, i.e. Figure 1 below.

[0040] Figure 1 The structure of the annular sealing device 100 according to the present application is shown. As shown in Figure 1 , the annular sealing device 100 comprises a central pipe 1, a piston 2, a support sleeve 3 and an outer cylinder assembly 4.

[0041] As shown in Figures 1 to 3 , the central pipe 1 is configured in a substantially cylindrical shape, and the outer cylinder assembly 4 is also configured in a substantially cylindrical shape, and the outer cylinder assembly 4 is coaxially fixedly sleeved outside the central pipe 1. The length of the outer cylinder assembly 4 is greater than the length of the central pipe 1, the upper end of the outer cylinder assembly 4 exceeds the upper end surface of the central pipe 1, and the inner diameter of the upper end of the outer cylinder assembly 4 is reduced to form a step, thereby axially abutting against the upper end surface of the central pipe 1. The lower end of the outer cylinder assembly 4 exceeds the lower end surface of the central pipe 1, and the inner diameter of the lower end of the outer cylinder assembly 4 is reduced to form a step, thereby axially abutting against the lower end surface of the central pipe 1.

[0042] A first sealing ring 81 is arranged between the outer wall of the upper end of the central pipe 1 and the inner wall of the outer cylinder assembly 4, and a second sealing ring 82 is arranged between the outer wall of the lower end of the central pipe 1 and the inner wall of the outer cylinder assembly 4, and the inner diameter of the outer cylinder assembly 4 is greater than the outer diameter of the central pipe 1, thereby forming an annular space 5 between the outer cylinder assembly 4 and the central pipe 1, the upper end of the annular space 5 is sealed by the first sealing ring 81, and the lower end of the annular space 5 is sealed by the second sealing ring 82.

[0043] As shown in Figure 2 , the piston 2 is configured in a substantially cylindrical shape, and the piston 2 is arranged outside the central pipe 1, specifically, the piston 2 is coaxially sleeved between the central pipe 1 and the outer cylinder assembly 4, that is, the piston 2 is arranged in the annular space 5. A third sealing ring 83 is arranged between the inner wall of the piston 2 and the central pipe 1, and a fourth sealing ring 84 is arranged between the outer wall of the piston 2 and the inner wall of the outer cylinder assembly 4. A pressure transmission hole 11 is arranged on the side wall of the central pipe 1, and the pressure transmission hole 11 is located above the third sealing ring 83, so that the pressure transmission hole 11 communicates with the upper end surface of the piston 2, and when the pressure inside the central pipe 1 rises, the pressure inside the central pipe 1 can be transmitted to the upper end surface of the piston 2 through the pressure transmission hole 11, thereby pushing the piston 2 to move downward relative to the central pipe 1.

[0044] The support sleeve 3 is configured in a substantially cylindrical shape, and the support sleeve 3 is arranged outside the central pipe 1, specifically, the support sleeve 3 is coaxially sleeved between the central pipe 1 and the outer cylinder assembly 4, the inner wall and the outer wall of the support sleeve 3 are in contact with the central pipe 1 and the outer cylinder assembly 4 respectively, and the support sleeve 3 is arranged below the piston 2. After the piston 2 moves downward relative to the central pipe 1, it can extend between the support sleeve 3 and the central pipe 1, thereby expanding the support sleeve 3 radially outward by mechanical extrusion, and further expanding the part of the outer cylinder assembly 4 in contact with the support sleeve 3 radially outward through the support sleeve 3, and finally the outer wall of the outer cylinder assembly 4 contacts the inner wall of the wellbore 10, as shown in Figure 4 , the setting is completed.

[0045] According to the present invention, the support sleeve 3 is configured to self-expand upon contact with the downhole fluid; that is, the support sleeve 3 is made of a self-expanding material. After contact with the downhole fluid, the support sleeve 3 can continue to expand, thereby further radially compressing the outer cylinder assembly 4 and strengthening the seal between the outer wall of the outer cylinder assembly 4 and the inner wall of the wellbore 10. This allows the present invention to adapt to large-sized wellbores and to have high pressure resistance after setting, facilitating large-scale fracturing operations with large displacement.

[0046] It should be noted that self-expanding materials are a common material for downhole tools and are well known to those skilled in the art, so they will not be described in detail here.

[0047] In this embodiment, the support sleeve 3 is made of materials such as copper and copper alloys, aluminum and aluminum alloys, or magnesium and magnesium alloys, preferably a soluble high-elongation magnesium-aluminum alloy. The elongation of the support sleeve 3 is preferably 30-40%.

[0048] According to a preferred embodiment of the present invention, in the initial state, the annular space 5 where the support sleeve 3 is located is sealed, meaning that the downhole fluid cannot contact the support sleeve 3, and the support sleeve 3 will not self-expand at this time. In the setting state, the annular space 5 where the support sleeve 3 is located is open, meaning that only after the piston 2 is pressed down and the support sleeve 3 and the outer cylinder assembly 4 are radially expanded by mechanical compression to complete the initial setting, can the downhole fluid contact the support sleeve 3, causing the support sleeve 3 to expand secondaryly, thereby enhancing the setting effect.

[0049] like Figure 1 and Figure 2 As shown, according to a specific embodiment of the present invention, the outer cylinder assembly 4 includes a sealing sleeve 41 and a fixing sleeve 42.

[0050] In this embodiment, a fixed sleeve 42 is coaxially fixedly sleeved on the upper part of the central tube 1, and the upper end of the fixed sleeve 42 extends beyond the upper end face of the central tube 1. A first sealing ring 81 is disposed between the inner wall of the upper end of the fixed sleeve 42 and the central tube 1. The lower part of the fixed sleeve 42 is located outside the piston 2, and a fourth sealing ring 84 is located between the fixed sleeve 42 and the piston 2. In this embodiment, the upper end of the fixed sleeve 42 is constructed as an upper connector that can be threadedly connected to other downhole tools.

[0051] The sealing sleeve 41 is coaxially fixedly sleeved on the lower part of the central tube 1, and the second sealing ring 82 is disposed between the inner wall of the lower end of the sealing sleeve 41 and the central tube 1. The upper part of the sealing sleeve 41 is located outside the support sleeve 3.

[0052] In the initial state, such as Figures 1 to 3As shown, the lower end of the fixed sleeve 42 is sealed to the upper end of the sealing sleeve 41. Simultaneously, the piston 2 is positioned above the support sleeve 3, and the inner wall of the piston 2 is sealed to the central tube 1 by a third sealing ring 83, while the outer wall of the piston 2 is sealed to the fixed sleeve 42 by a fourth sealing ring 84. This ensures that the annular space 5 containing the support sleeve 3 is sealed. With this configuration, downhole fluid cannot contact the support sleeve 3, thus preventing the support sleeve 3 from expanding prematurely before setting.

[0053] In the seated state, such as Figure 4 As shown, after piston 2 moves downward relative to the central tube 1, piston 2 extends between the support sleeve 3 and the central tube 1. The support sleeve 3 pushes the upper part of the sealing sleeve 41 to expand radially, thereby releasing the seal between the fixed sleeve 42 and the sealing sleeve 41, and thus opening the annular space 5 where the support sleeve 3 is located. Specifically, the upper end of the sealing sleeve 41 expands radially, while the lower end of the fixed sleeve 42 remains in its original position, thus misaligning the upper end of the sealing sleeve 41 with the lower end of the fixed sleeve 42 and creating a gap. The annular space 5 where the support sleeve 3 is located is in the open state, meaning that the downhole fluid can enter the annular space 5 through the gap between the upper end of the sealing sleeve 41 and the lower end of the fixed sleeve 42 and come into contact with the support sleeve 3. After the support sleeve 3 comes into contact with the downhole fluid, it expands itself, further radially compressing the sealing sleeve 41 and strengthening the seal between the sealing sleeve 41 and the wellbore 10.

[0054] According to a preferred embodiment of the present invention, a pin hole 421 is provided on the fixing sleeve 42, such that in the initial state... Figures 1 to 3 As shown, piston 2 is fixedly connected to fixed sleeve 42 via shear pin 422. At this time, piston 2 closes pin hole 421. In this embodiment, piston 2 closing pin hole 421 specifically means that piston 2 closes the space between pin hole 421 and pressure transmission hole 11. Specifically, fourth sealing ring 84 is located above pin hole 421, preventing fluid from flowing from pressure transmission hole 11 to pin hole 421.

[0055] In the set position, piston 2 cuts off shear pin 422 and moves downward relative to pin hole 421, as... Figure 4 As shown, the fourth sealing ring 84 is located below the pin hole 421, which is connected to the pressure transmission hole 11. Under this configuration, the downhole fluid inside the central tube 1 can sequentially pass through the gap between the pressure transmission hole 11, the pin hole 421, the upper end of the sealing sleeve 41, and the lower end of the fixed sleeve 42 to contact the support sleeve 3, causing the support sleeve 3 to self-expand.

[0056] According to a specific embodiment of the present invention, in the initial state, the upper end face of the sealing sleeve 41 axially abuts against the lower end face of the fixed sleeve 42, and a sealing element is provided between the upper end face of the sealing sleeve 41 and the lower end face of the fixed sleeve 42, thereby making the annular space 5 where the support sleeve 3 is located in a closed state.

[0057] According to a specific embodiment of the present invention, the sealing sleeve 41 includes a support sleeve 411, an expansion sealing sleeve 412, and a rubber sealing sleeve 413.

[0058] like Figure 2 As shown, the support cylinder 411 is coaxially disposed at the lower end of the expansion sealing sleeve 412, and the second sealing ring 82 is disposed between the lower end of the support cylinder 411 and the central tube 1, thereby sealing the lower part of the support cylinder 411 with the central tube 1.

[0059] The expansion sealing sleeve 412 is coaxially sleeved on the outside of the support sleeve 3, and the rubber sealing sleeve 413 is coaxially disposed on the outside of the expansion sealing sleeve 412. When the support sleeve 3 expands radially, it can radially squeeze the expansion sealing sleeve 412 outward, and then squeeze the rubber sealing sleeve 413, ultimately forming a seal between the outer wall of the rubber sealing sleeve 413 and the inner wall of the well barrel 10.

[0060] In a preferred embodiment, the expansion sealing sleeve 412 is made of metal and provides support for the rubber sealing sleeve 413.

[0061] In a preferred embodiment, the outer diameter of the expansion sealing sleeve 412 is smaller than the outer diameter of the support cylinder 411. After the rubber sealing sleeve 413 is disposed on the expansion sealing sleeve 412, the outer diameter of the rubber sealing sleeve 413 is equal to the outer diameter of the support cylinder 411. Further, the rubber sealing sleeve 413 is connected to the expansion sealing sleeve 412 by vulcanization. Alternatively, the rubber sealing sleeve 413 may simply be fitted onto the outside of the expansion sealing sleeve 412, and the two are not fixedly connected.

[0062] In a preferred embodiment, the thickness of the expansion sealing sleeve 412 ranges from 1 to 3.5 mm, and the thickness of the rubber sealing sleeve 413 ranges from 0.5 to 2 mm.

[0063] According to the present invention, the expansion sealing sleeve 412 is made of a metal material with certain strength and good ductility. Such metal materials can be copper and copper alloys, iron and iron alloys, titanium and titanium alloys, aluminum and aluminum alloys, magnesium and magnesium alloys, nickel-titanium alloys, etc.

[0064] According to the present invention, such as Figure 2 and Figure 3As shown, the upper end of the support sleeve 3 is configured with an inner diameter that gradually decreases from top to bottom, and the lower end of the piston 2 is configured with an outer diameter that gradually decreases from top to bottom. The outer diameter of the lower end of the piston 2 is smaller than the inner diameter of the upper end of the support sleeve 3. With this configuration, the piston 2 can easily enter between the support sleeve 3 and the central tube 1 during its downward movement.

[0065] According to the present invention, such as Figure 2 As shown, a wedge-shaped sleeve 6 is provided on the outside of the central tube 1, and is positioned below the support sleeve 3. The upper end of the wedge-shaped sleeve 6 is constructed with an outer diameter that gradually increases from top to bottom, while the lower end of the support sleeve 3 is constructed with an inner diameter that gradually increases from top to bottom. The outer diameter of the upper end of the wedge-shaped sleeve 6 is smaller than the inner diameter of the lower end of the support sleeve 3. With this arrangement, as the piston 2 moves downward, the support sleeve 3 also moves downward a certain distance, allowing the wedge-shaped sleeve 6 to easily enter between the support sleeve 3 and the central tube 1, thus enhancing the expansion effect of the support sleeve 3.

[0066] In one embodiment, the lower end of the piston 2, the upper and lower ends of the support sleeve 3, and the upper end of the wedge sleeve 6 are all configured as a tapered wedge surface with a taper range of 0 to 45 degrees.

[0067] Furthermore, such as Figure 2 As shown, the lower end inner diameter of the support cylinder 411 decreases to form an abutment cylinder 414, and the second sealing ring 82 is disposed between the abutment cylinder 414 and the central tube 1. The lower end face of the wedge sleeve 6 is in axial contact with the upper end face of the abutment cylinder 414, thereby preventing the wedge sleeve 6 from moving downward. With this configuration, when the piston 2 moves downward and pushes the support sleeve 3 downward, the wedge sleeve 6 remains stationary, thus facilitating the piston 2 and the wedge sleeve 6 to extend from the upper and lower ends of the support sleeve 3 respectively between the support sleeve 3 and the central tube 1.

[0068] In one specific embodiment, the outer casing assembly 4 also includes a lower connector 7 for connection to other downhole tools, such as... Figure 1 and Figure 2 As shown, the lower connector 7 is coaxially fixed on the lower outer side of the central tube 1, and the upper end face of the lower connector 7 is axially abutting the lower end face of the abutting cylinder 414.

[0069] In a preferred embodiment, the outer wall of the support sleeve 3 is arched, meaning that the outer diameter of the support sleeve 3 gradually decreases from the middle to the top and bottom ends. This design allows the support sleeve 3 to concentrate radial force on the outer cylinder assembly 4 at a single point when it expands radially under the pressure of the piston 2, thereby enhancing the sealing effect.

[0070] According to the present invention, the inner wall of the support sleeve 3 is configured to fit against the outer wall of the central tube 1.

[0071] According to the present invention, an annular sealing method is provided, which uses an annular sealing device 100 provided according to the present invention to perform annular sealing. After the annular sealing device 100 is lowered into the wellbore 10 to a predetermined depth, pressure is applied into the annular sealing device 100, causing the piston 2 to move downward relative to the central tube 1 and extend between the support sleeve 3 and the central tube 1, thereby causing the support sleeve 3 to expand radially, which in turn causes the expansion sealing sleeve 412 and the rubber sealing sleeve 413 to expand radially, and finally the rubber sealing sleeve 413 seals with the wellbore 10.

[0072] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0073] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0074] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0075] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on 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 spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An annular sealing device, characterized in that, include: Central tube (1); Piston (2) disposed outside the central tube (1); A support sleeve (3) disposed outside the central tube (1) and below the piston (2), the support sleeve (3) being configured to self-expand upon contact with downhole fluid; and The outer cylinder assembly (4) is located on the outside of the support sleeve (3); The piston (2) is configured to move downward under pressure and extend between the support sleeve (3) and the central tube (1), thereby causing the support sleeve (3) and the outer cylinder assembly (4) to expand radially. The support sleeve (3) continues to expand after contacting the downhole fluid.

2. The annular sealing device according to claim 1, characterized in that, The outer cylinder assembly (4) is coaxially disposed on the outside of the central tube (1), forming an annular space (5) between the outer cylinder assembly (4) and the central tube (1). The piston (2) and the support sleeve (3) are both disposed in the annular space (5). A pressure transmission hole (11) communicating with the upper end face of the piston (2) is provided on the side wall of the central tube (1).

3. The annular sealing device according to claim 2, characterized in that, In the initial state, the annular space (5) where the support sleeve (3) is located is sealed. In the set-off state, the annular space (5) where the support sleeve (3) is located is in the open state, so that the downhole fluid can come into contact with the support sleeve (3).

4. The annular sealing device according to claim 3, characterized in that, The outer cylinder assembly (4) includes: A sealing sleeve (41) is coaxially sleeved on the outside of the support sleeve (3), and the lower end of the sealing sleeve (41) extends beyond the support sleeve (3) and is sealed to the central tube (1). A fixed sleeve (42) is coaxially sleeved on the outside of the piston (2), the upper end of the fixed sleeve (42) extends beyond the piston (2) and is sealed to the central tube (1); In the initial state, the lower end of the fixed sleeve (42) is sealed to the upper end of the sealing sleeve (41), thereby making the annular space (5) where the support sleeve (3) is located sealed. In the set-sealed state, the support sleeve (3) pushes the upper end of the sealing sleeve (41) to expand radially, thereby releasing the seal between the fixed sleeve (42) and the sealing sleeve (41), and thus opening the annular space (5) where the support sleeve (3) is located.

5. The annular sealing device according to claim 4, characterized in that, A pin hole (421) is provided on the fixed sleeve (42), and the piston (2) is fixedly connected to the fixed sleeve (42) by a shear pin (422). In the initial state, the piston (2) closes the pin hole (421). In the set-sealed state, the piston (2) moves relative to the pin hole (421) so that the pin hole (421) communicates with the pressure transmission hole (11).

6. The annular sealing device according to claim 4, characterized in that, The upper end face of the sealing sleeve (41) abuts axially with the lower end face of the fixed sleeve (42), and a sealing element is provided between the upper end face of the sealing sleeve (41) and the lower end face of the fixed sleeve (42).

7. The annular sealing device according to claim 4, characterized in that, The sealing sleeve (41) includes: Support cylinder (411), the lower part of which is sealed to the central tube (1); An expansion sealing sleeve (412) is coaxially disposed at the upper end of the support cylinder (411), and the expansion sealing sleeve (412) is coaxially sleeved on the outside of the support sleeve (3); and A rubber sealing sleeve (413) is coaxially disposed on the outside of the expansion sealing sleeve (412).

8. The annular sealing device according to any one of claims 1 to 7, characterized in that, The upper end of the support sleeve (3) is configured to have an inner diameter that gradually decreases from top to bottom, and the lower end of the piston (2) is configured to have an outer diameter that gradually decreases from top to bottom.

9. The annular sealing device according to any one of claims 1 to 7, characterized in that, A wedge-shaped sleeve (6) is provided on the outside of the central tube (1). The wedge-shaped sleeve (6) is located below the support sleeve (3). The upper end of the wedge-shaped sleeve (6) is configured to have an outer diameter that gradually increases from top to bottom, and the lower end of the support sleeve (3) is configured to have an inner diameter that gradually increases from top to bottom.

10. A method for sealing annular spaces, characterized in that, An annular sealing device according to any one of claims 1 to 9 is used for annular sealing.

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