A high temperature resistant sealing system for metal packer

Abstract

The application provides a high-temperature-resistant sealing system of a metal packer, which comprises a central pipe, an outer cylinder, support blocks arranged in an annular space formed between the outer cylinder and the central pipe, and piston blocks arranged at axial ends of the support blocks, wherein the inner walls of the axial ends of the support blocks are configured as first taper surfaces, and the outer walls of the axial inner ends of the piston blocks are configured as second taper surfaces, and wherein the first taper surfaces are provided with inclined key grooves, and the second taper surfaces are provided with inclined protruding keys, and wherein the side walls of the central pipe are respectively provided with pressure transmission holes, and the liquid pressure in the central pipe is used to push the two piston blocks to move axially towards each other through the pressure transmission holes, so that the second taper surfaces are adapted to the corresponding first taper surfaces, and the inclined protruding keys are adapted to the corresponding inclined key grooves, thereby pushing the support blocks to expand radially and rotate circumferentially, and the outer cylinder is expanded radially to form a seal with an external casing.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development, and particularly relates to a high-temperature resistant sealing system for a metal packer. Background Art

[0002] Conventional packers utilize a rubber sleeve to isolate the casing annulus. These sleeves are typically made of a rubber-based elastomer composite material. These packers operate in demanding environments, often subject to high pressure, high temperature, and oily media. They are also subject to corrosion from hydrogen sulfide, steam, and acids. In such environments, rubber-based elastomer composites can swell with oil, age, and become over-crosslinked. This increases the material's hardness, decreases its strength and elasticity, and significantly reduces its crack growth resistance. This can lead to premature failure within a single use, resulting in seal failure. In practice, the significant degradation of rubber material properties with increasing temperature is the primary cause of high-temperature damage to rubber sleeves. Currently, commonly used rubber sleeves are made of materials such as NBR, HNBR, and FKM, with an indoor temperature rating of 100-175°C. Common packers contain rubber components, such as the sleeve and seals, which are susceptible to aging at high temperatures.

[0003] As oil and gas exploration and development progresses deeper, the temperatures that packers need to withstand are getting higher and higher, with bottomhole temperatures reaching as high as 250°C. However, the reliability and applicability of conventional packers in complex environments are difficult to effectively guarantee. Summary of the Invention

[0004] To address the aforementioned technical issues, the present invention provides a high-temperature-resistant sealing system for a metal packer, capable of forming a metal seal and significantly improving the packer's sealing performance. This high-temperature-resistant sealing system prevents piston retraction, achieving a permanent seal and thus preventing packer seal failure. The piston block simultaneously rotates circumferentially while pushing the support block radially, promoting circumferential expansion of the outer barrel. This effectively ensures uniform expansion of the outer barrel and significantly enhances the sealing effect.

[0005] To this end, according to the present invention, a high-temperature resistant sealing system for a metal packer is provided, comprising: a center tube; an outer tube sleeved on the radially outer side of the center tube, the two ends of the outer tube being fixedly connected to the center tube by plugs, thereby forming a closed annular space between the outer tube and the center tube in the radial direction; a support block arranged in the annular space, the inner walls of the two ends of the support block being configured as a first conical surface, and an oblique key groove being provided on the first conical surface; and piston blocks arranged at the axial ends of the support block, the two piston blocks being sleeved on the center tube, the outer wall of the axial inner end of the piston block being configured as a second conical surface, and An oblique cam is provided on the second conical surface; wherein, a hydraulic cavity is formed axially between each piston block and the corresponding plug, and a pressure transmission hole is provided on the side wall of the central tube corresponding to the hydraulic cavity. By throwing a ball and holding the pressure, the liquid pressure in the central tube passes through the pressure transmission hole and acts on the two piston blocks, so that the two piston blocks approach each other in the axial direction, and the second conical surface is adapted to the corresponding first conical surface, and the oblique cam is adapted to the corresponding oblique keyway, thereby pushing the support block to generate radial expansion and circumferential rotation, so that the outer tube expands radially to form a seal with the outer sleeve.

[0006] In one embodiment, the angle θ between the extension direction of the oblique cam on the piston block and the central axis of the piston block satisfies the following formula:

[0007] S*tanθ=1.6*π*(R2-R1) / n

[0008] Wherein, S is the distance that the piston block moves inward along the axial direction, n is the number of the oblique cams, R1 is the initial outer diameter of the support block, and R2 is the outer diameter of the support block after it is fully expanded.

[0009] In one embodiment, a first ratchet is provided on the inner wall of the piston block, and a second ratchet is provided on the outer wall surface of the central tube at the two end positions corresponding to the support block. The first ratchet can cooperate with the second ratchet and enable the two piston blocks to move only in the axial direction toward each other.

[0010] In one embodiment, an axially extending limiting keyway is provided on the inner wall of the piston block, and an axially extending limiting convex key is provided on the outer wall of the central tube.

[0011] The limiting keyway is adapted and installed with the limiting convex key, so that the piston block is circumferentially stationary relative to the central tube when pushing the supporting block to rotate circumferentially.

[0012] In one embodiment, the support block is constructed to include a plurality of elongated bodies, and the plurality of elongated bodies are cylindrically installed in the annular space.

[0013] In one embodiment, the outer surface of the axial middle region of the outer cylinder is configured in a corrugated shape, and the support block is installed at a position corresponding to the axial middle of the outer cylinder.

[0014] In one embodiment, first metal seals are respectively provided between the plug and the outer cylinder and the central pipe, and second metal seals are respectively provided between the piston block and the outer cylinder and the central pipe.

[0015] In one embodiment, the cross sections of the first metal seals and the second metal seals are configured in a W-shaped structure.

[0016] In one embodiment, the outer cylinder is made of NiTi alloy.

[0017] In one embodiment, the outer surface of the outer cylinder is provided with a metal spray layer.

[0018] Compared with the prior art, the application has the following advantages:

[0019] The metal packer high-temperature sealing system according to the application adopts a metal outer cylinder, can form a metal seal, and adopts a metal seal, greatly improving the sealing performance of the packer. The piston block can prevent back-off and achieve permanent sealing under the cooperation of the first and second ratchets, avoiding sealing failure. The piston block and the support block are matched through the cooperation of the second taper surface and the corresponding first taper surface, and the cooperation of the inclined key and the corresponding inclined key groove, so that the piston block can produce circumferential rotation while expanding radially to push the support block, promoting the circumferential expansion of the outer cylinder, effectively ensuring the uniform expansion of the outer cylinder, and enhancing the sealing effect. The metal packer compresses the metal outer cylinder through radial expansion, extrudes metal deformation, and realizes metal sealing, which has the advantages of high temperature resistance, corrosion resistance, reliable operation, high efficiency, etc. Moreover, the metal packer high-temperature sealing system does not have any rubber seal, relies on metal interference fit to realize sealing, and has a temperature resistance index of up to 300 DEG C, meeting the needs of oil and gas well operation. In addition, the metal packer high-temperature sealing system has a simple structure, and is convenient and fast to install and use. BRIEF DESCRIPTION OF DRAWINGS

[0020] The application will be described below with reference to the drawings.

[0021] Figure 1 The structure of the metal packer high-temperature sealing system according to the application is shown.

[0022] Figure 2 The structure of the metal packer high-temperature sealing system according to the application is shown. Figure 1 The structure of the metal packer high-temperature sealing system according to the application is shown.

[0023] Figure 3The matching structure of the piston block and the support block is shown.

[0024] Figure 4 Shows Figure 1 The structure of the piston block in the high-temperature resistant sealing system of the metal packer is shown.

[0025] Figure 5 Shows Figure 1 The structure of the central tube in the high temperature resistant sealing system of the metal packer is shown.

[0026] Figure 6 The structure of the first metal seal (second metal seal) is shown.

[0027] In this application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn to scale. DETAILED DESCRIPTION

[0028] The present invention will be described below with reference to the accompanying drawings.

[0029] Figure 1 The structure of the metal packer high temperature resistant sealing system 100 according to the present invention is shown. Figure 1 As shown, the metal packer high-temperature sealing system 100 includes a central pipe 1. Central pipe 1 has a central flow channel for fluid flow. Central pipe 1 has connectors at both ends for connecting to other downhole tool strings. In one embodiment, threaded connectors are constructed at both ends of central pipe 1. These connectors are quick and easy to install and effectively ensure a stable connection to other tool strings.

[0030] like Figure 1 As shown, the metal packer high temperature resistant sealing system 100 further includes an outer tube 2, the inner diameter of which is larger than the outer diameter of the central tube 1, and the outer tube 2 is sleeved radially outside the central tube 1. Both ends of the outer tube 2 are fixedly connected to the central tube 1 via plugs 3.

[0031] External threads are provided on the outer surface of the central tube 1 in areas corresponding to the ends of the outer tube 1. The plug 3 is constructed to include a cylindrical plug body and an end step provided at the axial outer end of the plug body, the end step extending radially outward. An internal thread is provided on the inner wall of the plug body. The plug 3 is adapted to be connected to the external thread of the central tube 1 via the internal thread, thereby being fixedly connected to the central tube 1, and the inner wall surface of the plug 3 is sealedly connected to the outer wall surface of the central tube 1. The end faces of the outer tube 2 respectively abut against the end steps of the plug 3 at both ends, so that the plug body is inserted between the central tube 1 and the outer tube 2. The plugs 3 at both ends of the outer tube 2 can be rotated to approach each other, thereby forming a fixed connection between the outer tube 2 and the central tube 1. The inner wall surfaces at both ends of the outer tube 2 are sealedly connected to the outer wall surface of the plug body. As a result, a closed annular space 21 is formed between the central tube 1 and the outer tube 2.

[0032] According to the present invention, at least two first metal seals 31 are provided between the plug 3 and the outer tube 2, and between the plug 3 and the center tube 1, respectively. For example, axially spaced sealing grooves can be provided on the inner and outer surfaces of the plug body of the plug 3, with the first metal seals 31 installed in the corresponding sealing grooves. It should be noted that the first metal seals provided between the plug 3 and the center tube 1 and the first metal seals provided between the plug 3 and the outer tube 2 differ only in size.

[0033] In one embodiment, the longitudinal cross section of the first metal seal 31 is configured as a W-shaped structure (see Figure 6 ), and the first metal seal 31 is made of NiTi alloy, which gives the first metal seal 31 a superelastic effect. This structure of the first metal seal 31 can significantly improve the sealing ability of the first metal seal 31, which is very beneficial for improving the sealing between the plug 3, the center tube 1, and the outer tube 2.

[0034] According to the present invention, the metal packer high-temperature resistant sealing system 100 further includes a support block 4 and two piston blocks 5 for driving the support block 4 to expand radially. The support block 4 and the piston block 5 are both disposed within the annular space 21, with the two piston blocks 5 disposed at both ends of the support block 4. The support block 4 and the piston block 5 are sleeved on the center tube 1, with the outer surface of the support block 4 in contact with the inner surface of the outer tube 2. A hydraulic chamber 6 is formed axially between each piston block 5 and the corresponding plug 3. Pressure transmission holes 11 are provided on the side walls of the center tube 1 corresponding to the hydraulic chamber 6, and the hydraulic chamber 6 communicates with the central flow channel inside the center tube 1 through the pressure transmission holes 11. Preferably, a plurality of pressure transmission holes 11 are provided at the same axial position on the side walls of the center tube 1 corresponding to the hydraulic chamber 6, and are evenly distributed in the circumferential direction. The two piston blocks 5 are configured to move axially closer to each other under the action of liquid pressure, thereby pushing the support block 4 to expand radially, thereby causing the outer tube 2 to expand radially to form a seal with the external casing.

[0035] like Figures 2 to 4 As shown, the inner walls of both ends of the support block 4 are configured as first tapered surfaces 41. Simultaneously, the outer wall of the axially inner end of the piston block 5 is configured as a second tapered surface 51 that mates with the first tapered surface 41. Under the action of liquid pressure, the two piston blocks 5 can axially approach each other, with the second tapered surfaces 51 mateably with the corresponding first tapered surfaces 41 of the support block 4, thereby driving the support block 4 to radially expand. The tapered angles of the first tapered surface 41 and the second tapered surface 51 are set within a range of 15-30 degrees.

[0036] According to the present invention, a plurality of oblique keyways 42 are provided on the first conical surface 41 of the support block 4, and the plurality of oblique keyways 42 are evenly distributed in the circumferential direction. An oblique key 52 that can adapt to the oblique keyways 42 is provided on the second conical surface 51 of the piston block 5. Under the action of liquid pressure, the two piston blocks 5 can approach each other axially. When the second conical surface 51 adapts to the corresponding first conical surface 41 of the support block 4, the oblique key 52 adapts to the corresponding oblique keyway 42, generating torque, causing the support block 4 to twist, thereby driving the support block 4 to simultaneously rotate circumferentially while expanding radially, thereby promoting circumferential expansion of the outer tube 2. This structure of the support block 4 and the piston block 5 can particularly ensure more uniform expansion of the outer tube 4, thereby achieving effective sealing, which can greatly improve the sealing between the outer tube 2 and the external sleeve.

[0037] According to one embodiment of the present invention, the support block 4 is constructed to include a plurality of elongated bodies 43. For example, it can be understood that the support block 4 is formed by cutting a cylindrical body multiple times symmetrically along the centerline. The plurality of elongated bodies 43 are cylindrically installed in the annular space 21, thereby forming a cylindrical structure that is sleeved on the central pipe 1. The plurality of elongated bodies 43 are separate components. In the initial state, the circumferential end faces of each elongated body 43 contact the circumferential end faces of adjacent elongated bodies 43. However, under the push of the piston blocks 5 at both ends, they can separate and expand radially outward.

[0038] According to the present invention, the angle θ between the extension direction of the oblique cam 51 on the piston block 5 and the central axis of the piston block 5 satisfies the following formula:

[0039] S*tanθ=1.6*π*(R2-R1) / n

[0040] Wherein, S is the distance that the piston block 5 moves inward along the axial direction, n is the number of the oblique cams 51, R1 is the initial outer diameter of the support block 4, and R2 is the outer diameter of the support block 4 after it is fully expanded.

[0041] By designing parameters such as the circumferential angle of the oblique convex key 51 and the conical angle of the head of the piston block 5, uniform expansion of the outer cylinder 2 can be achieved, thereby achieving effective sealing.

[0042] According to the present invention, Figure 3 As shown, first ratchet teeth 53 are provided on the inner wall of the piston block 5. Meanwhile, second ratchet teeth 12 are provided on the outer wall of the central tube 1 at the ends corresponding to the support blocks 4. The first ratchet teeth 53 cooperate with the second ratchet teeth 12 to allow the two piston blocks 5 to move only axially toward each other. This ensures that the piston blocks 5 will not retreat after the outer tube 2 is sealed, thereby ensuring a permanent seal for the outer tube 2.

[0043] According to one embodiment of the present invention, Figure 4As shown, a limiting key groove 54 extending in the axial direction is provided on the inner wall of the piston block 5. Figure 5 As shown, an axially extending stop key 13 is provided on the outer wall of the center tube 1. The stop key groove 54 fits snugly within the stop key 13, ensuring that the piston block 5 remains stationary relative to the center tube 1 while pushing the support block 4 in circumferential rotation. This effectively prevents the piston block 5 from rotating relative to the center tube 1 during the movement of the support block 4. This ensures that the support block 4 rotates circumferentially relative to the piston block 5 while radially expanding, ensuring uniform expansion of the outer tube 4.

[0044] To ensure a tight seal between the piston block 5 and both the center tube 1 and outer tube 2, second metal seals 32 are provided between the piston block 5 and the outer tube 2 and center tube 1, respectively. For example, axially spaced sealing grooves can be provided on the inner and outer surfaces of the piston block 5, with the second metal seals 32 installed in the corresponding sealing grooves. It should be noted that the second metal seals provided between the piston block 5 and the center tube 1 differ from those provided between the piston block 5 and the outer tube 2 only in size.

[0045] Preferably, the second metal seal 32 is constructed in the same manner as the first metal seal 31 and is also made of a superelastic NiTi alloy. This structure of the second metal seal 32 is particularly advantageous for improving the sealing between the piston block 5 and the central tube 1 and outer tube 2.

[0046] According to the present invention, the outer surface of the axial middle region of the outer cylinder 2 is configured to be corrugated. The support block 4 is installed at a position corresponding to the axial middle portion of the outer cylinder 2. The outer cylinder 2 is made of NiTi alloy, which gives the outer cylinder 2 a superelastic effect.

[0047] The outer tube 2 undergoes a special metal spraying treatment, forming a metal spray coating on its outer surface. This coating is formed by spraying a deformable metal material, such as aluminum alloy 4032-T6. When the outward expansion of the outer tube 2 is blocked, the metal spray coating and the corrugated structure of the outer tube 2 deform, achieving a metal seal. This significantly improves the sealing performance between the outer tube 2 and the external casing.

[0048] During actual operation of the metal packer high-temperature sealing system 100 according to the present invention, after the metal packer, its associated tools, and the tubing string are lowered to the predetermined downhole position, a ball is dropped to block the oil pipe, increasing the fluid pressure within the pipe. Hydraulic pressure acts on the axially outer end surfaces of the corresponding piston blocks 5 through the pressure-transmitting holes 7, pushing the piston blocks 5 toward the center, causing the two piston blocks 5 to axially approach each other. The second tapered surface 51 of the piston block 5 mates with the corresponding first tapered surface 41 of the support block 4, pushing the support block 4 axially. Simultaneously, the oblique key 52 of the piston block 5 mates with the corresponding oblique keyway 42 of the support block 4, generating torque that twists the support block 4, pushing it to rotate circumferentially while simultaneously expanding radially, thus promoting circumferential expansion of the outer tube 2. This causes the piston block 5 to simultaneously rotate circumferentially while pushing the support block 4 to expand radially. The corrugated central portion of the outer tube 2 expands radially outward under the action of the support block 4, contacting the inner wall of the outer casing. As the hydraulic pressure within the central tube 1 increases, the piston block 5 continues to push the support block 4 radially outward, causing the corrugated portion of the outer tube 2 to deform, forming a seal with the outer casing. During the packer's seating process, the first ratchet teeth 53 of the piston block 5 engage with the second ratchet teeth 12 on the central tube 1, limiting the two piston blocks 5 to unidirectional axial movement, toward each other. This ensures the packer's permanent seal even if the hydraulic pressure within the central tube 1 is removed.

[0049] The metal packer high-temperature sealing system 100 according to the present invention utilizes a metal outer tube, creating a metal seal. The metal seal significantly improves the packer's sealing performance. The piston block 5, through the cooperation of the first ratchet teeth 53 and the second ratchet teeth 12, prevents retraction, achieving a permanent seal and preventing seal failure. Between the piston block 5 and the support block 4, the second tapered surface 51 cooperates with the corresponding first tapered surface 41, and the oblique key 52 cooperates with the corresponding oblique keyway 42. This allows the piston block 5 to simultaneously push the support block 4 radially to expand and rotate circumferentially, promoting circumferential expansion of the outer tube 2. This effectively ensures uniform expansion of the outer tube 2 and enhances the sealing effect. The metal packer achieves a metal seal by radially expanding and compressing the metal outer tube, squeezing and deforming the metal. This metal packer exhibits advantages such as high-temperature resistance, corrosion resistance, reliable operation, and high efficiency. Furthermore, the metal packer high-temperature sealing system 100 lacks any rubber seals and relies on a metal interference fit to achieve sealing. Its temperature resistance can reach 300°C, meeting the requirements of oil and gas well operations. In addition, the metal packer high temperature resistant sealing system 100 has a simple structure and is quick and easy to install and use.

[0050] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A high-temperature resistant sealing system for a metal packer, comprising: Center tube (1) An outer cylinder (2) is sleeved on the radially outer side of the central tube, with both ends of the outer cylinder being fixedly connected to the central tube via plugs (3), thereby forming a closed annular space (21) between the outer cylinder and the central tube in the radial direction; A support block (4) is arranged in the annular space, wherein the inner walls at both ends of the support block are configured as first conical surfaces (41), and an oblique keyway (42) is provided on the first conical surface; and Piston blocks (5) are provided at both axial ends of the support block, the two piston blocks are sleeved on the central tube, the outer wall of the axial inner end of the piston block is configured as a second conical surface (51), and an oblique convex key (52) is provided on the second conical surface; A hydraulic cavity is formed between each piston block and the corresponding plug in the axial direction, and a pressure transmission hole (11) is provided on the side wall of the central tube corresponding to the hydraulic cavity. By throwing the ball and holding the pressure, the liquid pressure in the central tube passes through the pressure transmission hole and acts on the two piston blocks, so that the two piston blocks approach each other in the axial direction, and the second conical surface is adapted to the corresponding first conical surface, and the oblique convex key is adapted to the corresponding oblique key groove, thereby pushing the support block to generate radial expansion and circumferential rotation, so that the outer tube expands radially to form a seal with the outer sleeve.

2. The metal packer high temperature resistant sealing system according to claim 1, characterized in that: The angle θ between the extension direction of the oblique cam on the piston block and the central axis of the piston block satisfies the following formula: S*tanθ=1.6*π*(R2-R1) / n Wherein, S is the distance that the piston block moves inward along the axial direction, n is the number of the oblique cams, R1 is the initial outer diameter of the support block, and R2 is the outer diameter of the support block after it is fully expanded.

3. The high temperature resistant sealing system of the metal packer according to claim 1 or 2, characterized in that: A first ratchet (53) is provided on the inner wall of the piston block, and a second ratchet (12) is provided on the outer wall surface of the central tube at the two end positions corresponding to the support block. The first ratchet can cooperate with the second ratchet and enable the two piston blocks to move only in the axial direction toward each other.

4. The high temperature resistant sealing system of the metal packer according to claim 1 or 2, characterized in that: An axially extending limiting keyway (54) is provided on the inner wall of the piston block, and an axially extending limiting convex key (13) is provided on the outer wall of the central tube. The limiting keyway is adapted and installed with the limiting convex key, so that the piston block is circumferentially stationary relative to the central tube when pushing the supporting block to rotate circumferentially.

5. The high temperature resistant sealing system of the metal packer according to claim 1, characterized in that: The support block is constructed to include a plurality of long strip bodies (43), and the plurality of long strip bodies are installed in the annular space in a cylindrical shape.

6. The high temperature resistant sealing system of the metal packer according to claim 1, characterized in that: The outer surface of the axial middle region of the outer cylinder is configured to be corrugated, and the support block is installed at a position corresponding to the axial middle of the outer cylinder.

7. The high temperature resistant sealing system of the metal packer according to claim 1, characterized in that: A first metal seal (31) is provided between the plug and the outer tube and the central tube, respectively; and a second metal seal (32) is provided between the piston block and the outer tube and the central tube, respectively.

8. The high temperature resistant sealing system of the metal packer according to claim 7, characterized in that: The cross sections of the first metal seal and the second metal seal are both configured in a W-shaped structure.

9. The high temperature resistant sealing system of the metal packer according to claim 1, characterized in that: The outer cylinder is made of NiTi alloy.

10. The high temperature resistant sealing system of the metal packer according to claim 9, characterized in that: The outer surface of the outer cylinder is provided with a metal spray layer.

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