Underground injection-production string preset working barrel and sealing working barrel

Abstract

According to the preset working barrel and the sealing working barrel of the underground injection-production pipe column, a locking ring provided with a horse tooth buckle is arranged in the preset working barrel and is installed between an upper outer barrel and a lower outer barrel, and the upper outer barrel is connected with the lower outer barrel; and the preset working barrel is tripped into a preset position in a well along with the well completion pipe column in advance. A working barrel is sealed, a sealing component is arranged, a backwashing hole and a backwashing control hole are formed in an inner barrel, and a horse tooth buckle is machined in the inner barrel; the sealing working barrel is connected to the lower end of the injection-production pipe column and enters the preset working barrel, an inner barrel of the sealing working barrel is connected with a horse tooth buckle in a locking ring, a sealing insertion barrel seals a sealing insertion barrel sealing cavity of the lower outer barrel, and a sealing assembly seals a sealing piece sealing cavity of the lower outer barrel. The working principle is simple and reliable, the anchoring sealing capacity is improved, meanwhile, the safety of the whole tool is enhanced, an inverse well flushing process channel is provided, the probability of underground accidents caused by incrustation blockage or paraffin precipitation blockage in a pipe column after an injection and production well is put into production is greatly reduced, and the using effect is remarkable.

Description

Technical Field

[0001] The present invention relates to a downhole injection-production string in oilfield development in the petroleum industry, and specifically to a downhole injection-production string pre-set working barrel and a sealing working barrel. Background Art

[0002] With the continuous development of domestic gas storage construction, the application conditions and working conditions of the injection-production string in the gas storage are becoming increasingly harsh. If the injection-production string of a conventional natural gas storage is directly applied to an air energy storage type gas storage, it will be found that many parts are not applicable. In particular, the injection-production string of the injection-production well in a natural gas type gas storage basically uses a gas-tight packer to anchor and seal the annulus between the casing and the tubing. For example: The "Injection-Production String and Completion Method Using the Same" disclosed in the authorized announcement number CN112647857B and the "Completion String for an Injection-Production Well in a Gas Storage of Oil and Gas Reservoir Type" disclosed in the authorized announcement number CN206205797U relate to the injection-production string in the gas storage.

[0003] However, the above technical solutions cannot meet the requirements of long-term effective anchoring and sealing of the injection-production well in a compressed air gas storage.

[0004] Since the injection-production cycle of the injection-production well in a compressed air gas storage is once a day, the working conditions of its downhole string are more severe compared with other types of gas storages. As described in articles such as "Research on the Dynamic Characteristics of Fluid-Induced Vibration and Buckling of Injection-Production String in Gas Storage" and "Buckling Behavior of Tubing in Gas Storage under Multi-Cycle Injection-Production Conditions", the core factor determining whether the rubber barrel in the gas-tight packer can be sealed effectively for a long time under high pressure is the cleanliness of the inner wall of the casing in contact with the rubber barrel and whether creep occurs between the two, which leads to damage to the rubber barrel, and thus has extremely high requirements for the anchoring ability of the packer.

[0005] However, facts have proved that it is difficult for the working principle of the existing gas-tight packer to ensure no creep under high-frequency and large-amplitude alternating stress conditions. Therefore, how to solve the problem of the short service life of such injection-production strings has become a key issue in determining the popularization and application of compressed air type gas storages.

[0006] Currently, in the field of oil development, in addition to using a packer to anchor and seal the downhole injection-production string, there is also a method of using a combination of a sealing working barrel and a sealing plug to achieve the sealing or layering of the annulus between the casing and the tubing. For example: The "Controllable Section Sealing Device for Downhole Tools and Downhole Working Barrel Sealing" disclosed in the authorized announcement number CN101403284B and the "Plugging Packing Device" disclosed in the authorized announcement number CN104912512B can both meet the sealing of the annulus between the casing and the tubing or the sealing of different intervals, but neither of them has the locking function for the injection-production string.

[0007] The cooperation between the sealing plug pipe and the sealing working barrel involved in the "Completion String for CO 2 Water Alternating Injection Well and Its Completion Method and Service String" disclosed in the authorized announcement number CN111980610A has the functions of anchoring and sealing. However, due to the limitations of its working principle, not only is the structure complex, but the cooperation of the anchoring mechanism is also relatively rough. The sealing plug pipe has a certain distance of creeping space, resulting in creeping under the conditions of high-frequency and large-amplitude alternating stress. The sealing ring therein is extremely easy to wear and fail, and it is very difficult to ensure long-term and effective operation underground.

[0008] Therefore, there is an urgent need to develop an efficient sealing tool with a long service life to solve the above problems. Summary of the Invention

[0009] To solve the above problems existing in the prior art, the present invention provides a preset working barrel and a sealing working barrel for downhole injection and production strings, mainly used to solve the problem of long-term anchoring and sealing of injection and production strings for gas storage under the working conditions of high-frequency and large-amplitude alternating stress, improve the service life and sealing effect of the sealing tool, extend the maintenance cycle of the injection and production string, and reduce production costs.

[0010] The technical solution of the present invention is: A preset working barrel for downhole injection and production strings is provided with an upper outer barrel and a lower outer barrel, wherein: A locking ring with a buttress thread is installed between the upper outer barrel and the lower outer barrel, and the upper outer barrel is connected to the lower outer barrel; The preset working barrel is pre-lowered into a preset position in the well together with the completion string.

[0011] Preferably, the top of the ring body of the locking ring is provided with a locking ring torque transmission spline, the inner circle of the lower part of the locking ring is provided with a buttress thread, and the locking ring is an open ring axially provided with a straight or inclined through groove.

[0012] Preferably, the upper outer barrel is a non-uniform diameter cylindrical body. The upper inner cavity of the upper outer barrel is provided with an internal thread for connecting with the completion string, the lower part is a threaded inner cavity, and the middle inner cavity is provided with a locking ring limit step, and an upper outer barrel torque transmission spline is provided on the inner circle of the locking ring limit step; The upper outer barrel torque transmission spline can be connected to the locking ring torque transmission spline at the top of the locking ring body, and after connection, the locking ring is exactly located in the locking ring installation cavity between the locking ring limit step and the lower threaded inner cavity.

[0013] Preferably, the lower outer barrel is a non-uniform diameter cylindrical body. The outer circles at both ends of the lower outer barrel are provided with external threads and can be respectively threadedly connected to the internal threads in the threaded inner cavity of the lower part of the upper outer barrel and the lower casing in the completion string; The upper inner cavity of the lower outer barrel is a sealing plug barrel sealing cavity, and the lower inner cavity is a seal sealing cavity, and the sealing plug barrel sealing cavity is a conical cavity.

[0014] A sealing working barrel used in cooperation with a downhole injection-production pipe string pre-set working barrel is provided with a sealing component, wherein: the sealing component includes a sealing insertion barrel and a sealing assembly; an inner barrel is provided with a backwashing hole and a backwashing control hole; a tooth-shaped thread is machined on the outer circle of the limiting step three in the inner barrel; an upper locking ring, a sliding barrel and a spring are sequentially installed above the limiting step three from top to bottom; a disc spring, a sealing insertion barrel, a middle locking ring, a sealing assembly and a sealing pressing ring are sequentially installed below the limiting step three from top to bottom; the sealing working barrel is connected to the lower end of the injection-production pipe string and lowered into the pre-set working barrel, the inner barrel is connected to the tooth-shaped thread in the locking ring, the sealing insertion barrel seals the sealing insertion barrel cavity of the lower outer barrel, and the sealing assembly seals the sealing part cavity of the lower outer barrel.

[0015] Preferably, the sealing insertion barrel can be made of rubber or polymer material, soft metal or shape memory alloy. The lower outer circle of the sealing insertion barrel is a conical outer circle, and this conical outer circle cooperates with the sealing insertion barrel cavity of the lower outer barrel; a disc spring top ring is also installed between the disc spring and the sealing insertion barrel.

[0016] Preferably, the inner barrel is a non-uniform diameter cylindrical body, and injection-production pipe string connection threads and spare part connection threads are respectively arranged at the upper and lower ends of the inner barrel; limiting steps one, two, three, four and five are sequentially arranged on the outer circle of the inner barrel from top to bottom, and the outer circles of the limiting steps one, two, three, four and five are all precision machined outer circle surfaces.

[0017] Preferably, the backwashing hole and the backwashing control hole are arranged in the limiting step one. The backwashing hole is arranged in the outer circle below the injection-production pipe string connection thread, and sealing ring grooves one and sealing rings are arranged on the upper and lower sides of the backwashing hole; the backwashing control hole is arranged at the root of the limiting step one, and at least one sealing ring groove two is arranged on the outer circle at the top of the limiting step two; the outer diameter of the limiting step three is the largest, and a tooth-shaped thread is machined on this outer circle. A middle locking ring connection thread is arranged at the lower end of the outer circle of the limiting step four; a spare part connection thread is machined at the lower part of the limiting step five.

[0018] Preferably, the middle locking ring is provided with a central hole and an internal thread on the inner circle. After the middle locking ring is sleeved outside the inner barrel, the internal thread on its inner circle is threadedly connected to the middle locking ring connection thread; the sealing assembly is a combined seal, which at least includes one sealing ring and protective rings made of polytetrafluoroethylene respectively installed on both sides of the sealing ring. The outer diameter of the sealing ring is larger than the inner diameter of the sealing part cavity in the lower outer barrel; a limiting ring is also installed between the middle locking ring and the sealing assembly; the sealing pressing ring is threadedly connected to the spare part connection thread at the lower part of the limiting step five, and a lower pressing ring and a soluble plug are also connected below the sealing pressing ring.

[0019] Preferably, the inner circle of the sliding cylinder is processed with two inner diameters that are smaller at the top and larger at the bottom. The smaller inner diameter section is installed outside the first limiting step of the inner cylinder, and the larger inner diameter section is installed outside the second limiting step. Both inner diameters of the inner circle of the sliding cylinder are precision-machined surfaces. In the normal working state of the sliding cylinder, the smaller inner diameter section blocks the backwashing hole, and the larger inner diameter section communicates with the backwashing control hole.

[0020] Compared with the prior art, the present invention has the following remarkable usage effects: Between the preset working cylinder and the sealed working cylinder in the present invention, axial locking is carried out through a locking ring with a buttress thread and a disc spring capable of storing pressure. The locking ring cooperates with the buttress thread in the inner cylinder of the sealed working cylinder, and the disc spring is tensioned by the pipe string downward pressure below the third limiting step 2-107 of the inner cylinder, minimizing the creep between the sealed working cylinder and the preset working cylinder and improving the anchoring ability of the injection-production pipe string.

[0021] The present invention is sealed through two sealing structures, namely a sealed insertion cylinder and a sealing assembly. Compared with conventional sealing tools of the same type, the sealing ability of the tool is greatly improved.

[0022] In the inner cylinder of the sealed working cylinder in the present invention, there are a backwashing hole and a backwashing control hole, with a self-backwashing well function. During normal injection-production work, a casing protection fluid can be pumped into the annulus between the tubing and the casing. The pumped casing protection fluid can reduce the corrosion of the annulus between the injection-production pipe string and the casing.

[0023] After the injection-production cycle ends, maintenance can be carried out without moving the pipe string. Since the present invention has a backwashing well channel, a washing fluid with a cleaning function can be circulated in reverse to clean the scale and wax on the tubing.

[0024] The present invention can achieve maintenance without moving the pipe string, reducing the conventional operation costs and time, extending the service life of the injection-production pipe string, and improving the working efficiency of the gas storage reservoir.

[0025] The inner cylinder of the sealed working cylinder has a self-backwashing well function. During a blowout, it is easier to kill the well through reverse circulation, effectively reducing the difficulty of killing the well during a blowout and improving the safety factor of the injection-production well in terms of process principle.

[0026] Compared with a packer, the working principle of the present invention is simple and reliable. While improving the anchoring and sealing ability, it enhances the safety of the whole set of tools, provides a backwashing well process channel, greatly reduces the probability of downhole accidents caused by scale blockage or wax blockage in the pipe string after the injection-production well is put into production, and at the same time reduces the requirements for the casing material above the preset working cylinder, saving its processing cost. At the same time, the present invention can also be used in wells for injecting carbon dioxide.

[0027] In summary, the present invention extends the service life of the injection-production pipe string, improves the working efficiency of the gas storage reservoir, has a huge promotion space, and can generate good economic and social benefits. Brief Description of the Drawings

[0028] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings: Figure 1 is a schematic structural view of the combined connection of the sealing working cylinder and the preset working cylinder in the present invention.

[0029] Figure 2 is a schematic structural view of the preset working cylinder in the present invention.

[0030] Figure 3 is a schematic structural view of the upper outer cylinder in the preset working cylinder.

[0031] Figure 4 is a schematic structural view of the locking ring in the preset working cylinder.

[0032] Figure 5 is a schematic structural view of the sealing working cylinder in the present invention.

[0033] Figure 6 is a schematic structural view of the inner cylinder in the sealing working cylinder.

[0034] In the figure: Preset working cylinder 1: upper outer cylinder 1-1, upper outer cylinder torque transmission spline 1-11; locking ring 1-2, locking ring torque transmission spline 1-21; lower outer cylinder 1-3.

[0035] Sealing working cylinder 2: inner cylinder 2-1, backwashing hole 2-101, sealing ring groove 1 2-102, limiting step 1 2-103, backwashing control hole 2-104, sealing ring groove 2 2-105, limiting step 2 2-106, limiting step 3 2-107, limiting step 4 2-108, middle locking ring connection thread 2-109, limiting step 5 2-110; upper locking ring 2-2, sliding cylinder 2-3, spring 2-4, disc spring 2-5, disc spring top ring 2-6, sealing insertion cylinder 2-7, middle locking ring 2-8, limiting ring 2-9, sealing assembly 2-10, sealing pressure ring 2-11, lower locking ring 2-12. Detailed Description of the Preferred Embodiments

[0036] The drawings are only for reference and illustration purposes, and are not intended to limit the protection scope of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, in the description of the present invention, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0039] See Figures 1-6 , a downhole injection-production pipe string pre-installed working barrel, which is provided with an upper outer barrel 1-1 and a lower outer barrel 1-3, wherein: A locking ring 1-2 with a buttress thread is installed between the upper outer barrel 1-1 and the lower outer barrel 1-3, and the upper outer barrel 1-1 is connected to the lower outer barrel 1-3; the pre-installed working barrel 1 is pre-lowered into a preset position in the well together with the completion string.

[0040] Based on the above-mentioned first embodiment, the present invention also has the following embodiments: A preferred embodiment: The top of the ring body of the locking ring 1-2 is provided with a locking ring torque transmission spline 1-21, the lower inner circle of the locking ring 1-2 is provided with a buttress thread, and the locking ring 1-2 is an open ring with a straight or oblique through groove axially opened.

[0041] A preferred embodiment: The upper outer barrel 1-1 is a non-uniform diameter cylindrical body. The upper inner cavity of the upper outer barrel 1-1 is provided with an internal thread for connecting with the completion string, the lower part is a threaded inner cavity, and the middle inner cavity is provided with a locking ring limiting step and an upper outer barrel torque transmission spline 1-11 is provided on the inner circle of the locking ring limiting step; the upper outer barrel torque transmission spline 1-11 can be connected to the locking ring torque transmission spline 1-21 at the top of the ring body of the locking ring 1-2, and after connection, the locking ring 1-2 is exactly located in the locking ring installation cavity between the locking ring limiting step and the lower threaded inner cavity.

[0042] A preferred embodiment: The lower outer barrel 1-3 is a non-uniform diameter cylindrical body. The outer circles at both ends of the lower outer barrel 1-3 are provided with external threads and can be respectively threadedly connected to the internal thread in the lower threaded inner cavity of the upper outer barrel 1-1 and the lower casing in the completion string; the upper inner cavity of the lower outer barrel 1-3 is a sealed insert barrel sealing cavity, and the lower inner cavity is a seal sealing cavity, and the sealed insert barrel sealing cavity is a conical cavity.

[0043] A sealing working barrel used in conjunction with the above-mentioned downhole injection-production string pre-set working barrel is provided with a sealing component, wherein: the sealing component includes a sealing insertion barrel 2-7 and a sealing assembly 2-10; the inner barrel 2-1 is provided with a backwashing hole 2-101 and a backwashing control hole 2-104; the outer circle of the limiting step three 2-107 in the inner barrel 2-1 is processed with a buttress thread; the upper locking ring 2-2, the sliding barrel 2-3 and the spring 2-4 are sequentially installed above the limiting step three 2-107 from top to bottom; the disc spring 2-5, the sealing insertion barrel 2-7, the middle locking ring 2-8, the sealing assembly 2-10, and the sealing pressing ring 2-11 are sequentially installed below the limiting step three 2-107 from top to bottom; the sealing working barrel 2 is connected to the lower end of the injection-production string and lowered into the pre-set working barrel 1, the inner barrel 2-1 is connected to the buttress thread in the locking ring 1-2, the sealing insertion barrel 2-7 seals the sealing insertion cavity of the lower outer barrel 1-3, and the sealing assembly 2-10 seals the sealing cavity of the seal in the lower outer barrel 1-3.

[0044] In the present invention, the pre-set working barrel 1 is lowered in advance by the completion string and cemented in the wellbore together with the completion string. The sealing working barrel 2 is connected to the lower end of the injection-production string and lowered into the pre-set working barrel 1. The two are tightly connected together through the buttress thread on the outer circle of the locking ring 1-2 and the limiting step three 2-107 in the inner barrel 2-1. Since the torque transmission spline 1-21 at the top of the locking ring 1-2 engages with the upper outer barrel torque transmission spline 1-11, it can be released by reverse threading through the torque transmission spline when pulling out the injection-production string; at the same time, the disc spring 2-5 effectively restricts the creep of the injection-production string, making the sealing insertion barrel 2-7 tightly pressed in the sealing insertion cavity of the lower outer barrel 1-3, and the sealing assembly 2-10 is pressed tightly in the sealing cavity of the seal in the lower outer barrel 1-3 by the sealing pressing ring 2-11.

[0045] Through the above anti-creep and double-sealing measures, the sealing effect between the sealing working barrel 2 and the pre-set working barrel 1 is ensured and improved, and the problem that the injection-production string for the gas storage reservoir connected above the inner barrel 2-1 cannot be anchored and sealed for a long time under the working conditions of high-frequency and large-amplitude alternating stress can be effectively solved. At the same time, the service life and sealing effect of the tool of the present invention are improved, the maintenance cycle of the injection-production string is extended, and the production cost is reduced.

[0046] Based on the above-mentioned first embodiment, the present invention also has the following embodiments: A preferred embodiment: The sealing insertion cylinder 2-7 can be made of rubber or polymer materials, soft metal or shape memory alloy. The outer circle of the lower part of the sealing insertion cylinder 2-7 is a conical outer circle, and this conical outer circle cooperates with the sealing insertion cavity of the lower outer cylinder 1-3; A disc spring top ring 2-6 is also installed between the disc spring 2-5 and the sealing insertion cylinder 2-7. Polymer materials include engineering resins and engineering plastics, and soft metals include copper and lead. The disc spring top ring 2-6 can provide protection for the top end of the sealing insertion cylinder 2-7, and during operation, the disc spring top ring 2-6 can provide an anti-loosening tightening force for the horse tooth buckle, improving and strengthening the tightening effect of the disc spring 2-5 on the sealing insertion cylinder 2-7, and further improving the sealing effect.

[0047] A preferred embodiment: The inner cylinder 2-1 is a non-uniform diameter cylinder. Injection-production pipe string connection threads and spare part connection threads are respectively arranged at the upper and lower ends of the inner cylinder 2-1; Limiting steps one 2-103, limiting steps two 2-106, limiting steps three 2-107, limiting steps four 2-108 and limiting steps five 2-110 are successively arranged on the outer circle of the inner cylinder 2-1 from top to bottom. The outer circles of the limiting steps one 2-103, limiting steps two 2-106, limiting steps three 2-107, limiting steps four 2-108 and limiting steps five 2-110 are all precision-machined outer circle surfaces.

[0048] A preferred embodiment: The backwashing hole 2-101 and the backwashing control hole 2-104 are arranged in the limiting step one 2-103. The backwashing hole 2-101 is arranged in the outer circle below the injection-production pipe string connection thread, and sealing ring grooves one and sealing rings are arranged on the upper and lower sides of the backwashing hole 2-101; The backwashing control hole 2-104 is arranged at the root of the limiting step one 2-103, and at least one sealing ring groove two 2-105 is arranged on the outer circle of the top of the limiting step two 2-106; The outer diameter of the limiting step three 2-107 is the largest, and horse tooth buckles are machined on this outer circle. A middle locking ring connection thread 2-109 is arranged at the lower end of the outer circle of the limiting step four 2-108; Spare part connection threads are machined at the lower part of the limiting step five 2-110.

[0049] A preferred embodiment: The middle locking ring 2-8 is provided with a central hole and internal threads on its inner circle. After the middle locking ring 2-8 is sleeved outside the inner cylinder 2-1, the internal threads on its inner circle are threadedly connected with the middle locking ring connection thread 2-109 ，Provide support for the sealed insert cylinder 2-7; the sealing assembly 2-10 is a combined seal, which at least includes a sealing ring and protective rings made of polytetrafluoroethylene respectively installed on both sides of the sealing ring. The outer diameter of the sealing ring is greater than the inner diameter of the seal cavity of the seal in the lower outer cylinder 1-3; a limiting ring 2-9 is also installed between the middle locking ring 2-8 and the sealing assembly 2-10; the sealing pressure ring 2-11 is threadedly connected to the connecting thread of the spare part at the lower part of the limiting step five 2-110, and a lower pressure ring 2-12 and a soluble plug are also connected below the sealing pressure ring 2-11. Further provide pressing and locking force for the sealing assembly 2-10 and the sealing pressure ring 2-11 and prevent the sealing pressure ring 2-11 from loosening.

[0050] A preferred embodiment: The inner circle of the sliding cylinder 2-3 is processed with two inner diameters that are smaller at the top and larger at the bottom. The small inner diameter section is installed outside the limiting step one 103 of the inner cylinder 2-1, and the large inner diameter section is installed outside the limiting step two 106; both inner diameters of the inner circle of the sliding cylinder 2-3 are precision machined surfaces; when the sliding cylinder 2-3 is in the normal working state, the small inner diameter section blocks the backwashing hole 2-101, and the large inner diameter section communicates with the backwashing control hole 2-104. During the processes of backwashing the well, pumping the casing protection fluid into the annulus between the tubing and the casing, and reverse circulation killing the well, under the action of the pressure difference, the sliding cylinder 2-3 moves downward to expose the backwashing hole 2-101, forming a backwashing channel; the backwashing control hole 2-104 drains the liquid in the inner cavity of the sliding cylinder 2-3 into the tubing to prevent a dead cavity from being formed when the sliding cylinder 2-3 moves downward and hinder the downward movement of the sliding cylinder 2-3. After the backwashing operation is completed, under the pushing force of the spring 2-4, the sliding cylinder 2-3 moves upward and closes the backwashing hole 2-101, closing the oil-casing communication channel, see Figure 1 and Figure 5 。

[0051] The present invention is composed of two parts, a preset working cylinder 1 and a sealed working cylinder 2, and they are used in cooperation. The inner wall of the locking ring 1-2 in the preset working cylinder 1 is processed with a buttress thread, and the upper end is also processed with a locking ring torque transmission spline 1-21 that matches the upper outer cylinder torque transmission spline 1-11 in the upper outer cylinder 1-1. The two are in spline fit to achieve the torque transmission function. The buttress thread on the inner wall of the locking ring 1-2 is tightly connected to the buttress thread in the inner cylinder 2-1 to achieve the axial one-way locking function.

[0052] After the sealed working cylinder 2 is connected to the preset working cylinder 1, below the limiting step three 2-107 that is tightly connected to the buttress thread, a disc spring 2-5 and a disc spring top ring 2-6 are further assembled. When the injection-production string is pressed down, due to the limitation of the preset working cylinder 1, the disc spring top ring 2-6 can effectively transmit the axial pressure, compress the disc spring 2-5, store a certain tonnage of pressure, and prevent the buttress thread between the preset working cylinder 1 and the sealed working cylinder 2 from creeping within the range of one pitch. A middle locking ring 2-8 threadedly connected to the inner cylinder 2-1 is also provided below the sealed insert cylinder 2-7 to limit and tightly hold the sealed insert cylinder 2-7.

[0053] In addition to the sealed insertion cylinder 2-7 of the present invention being able to achieve sealing between the preset working cylinder 1 and the sealed working cylinder 2, a sealing assembly 2-10 is also provided below it, with at least one sealing ring and two retaining rings provided, adding another sealing barrier to the present invention, ensuring the sealing effect of the present invention, extending the service life of this sealing tool and the injection-production string, and reducing the production cost.

[0054] The working principle of the present invention is that the preset working cylinder 1 is first fixed underground, and then the sealed working cylinder 2 is connected to the lowermost end of the injection-production string and lowered into the well by the injection-production string.

[0055] After the sealed working cylinder 2 is inserted into the preset working cylinder 1, the sealed insertion cylinder 2-7 and the sealing assembly 2-10 cooperate with the corresponding sealing surfaces in the preset working cylinder 1 to achieve the sealing of the casing annulus; at the same time, the buttress threads on the outer wall of the limit step three 2-107 of the inner cylinder 2-1 in the sealed working cylinder 2 cooperate with the locking ring 1-2 in the preset working cylinder 1 to achieve axial anti-backlash locking; in addition, a part of the pressing tonnage of the injection-production string is transmitted to the disc spring 2-5 through the sealed insertion cylinder 2-7, and the disc spring 2-5 compresses and stores a certain tonnage of pressure to prevent the buttress threads from creeping within the range of one pitch.

[0056] The disc spring 2-5 stores energy due to the downward pressure of the injection-production string, and can always ensure the tension force of the cooperation between the buttress threads in the preset working cylinder 1 and the sealed working cylinder 2, reducing the damage of the sealing assembly 2-10 caused by the creeping of the injection-production string. The sliding sleeve 2-3 is in a closed state during normal operation. When the injection-production string needs to perform reverse circulation well washing, pump in casing protection fluid or encounter downhole overflow accidents, washing fluid or kill fluid can be pumped into the casing annulus through the oil-casing annulus to provide a process channel for the cleaning or kill operation of the injection-production string.

[0057] The embodiments described above are only typical embodiments, but the present invention is not limited to these embodiments. Those skilled in the art can make modifications without departing from the spirit and inspiration of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the creative spirit and creative concept of the present invention shall be included within the protection scope of the present invention. Therefore, the protection scope is not limited to the above description.

Claims

1. An underground injection-production string pre-set working barrel is provided with an upper outer barrel (1-1) and a lower outer barrel (1-3). Its feature is that a locking ring (1-2) with a buttress thread is installed between the upper outer barrel (1-1) and the lower outer barrel (1-3), and the upper outer barrel (1-1) is connected to the lower outer barrel (1-3); the pre-set working barrel (1) is pre-lowered into a pre-set position in the well together with the completion string.

2. An underground injection-production string pre-set working barrel according to claim 1, Its feature is that the top of the ring body of the locking ring (1-2) is provided with a locking ring torque transmission spline (1-21), the inner circle of the lower part of the locking ring (1-2) is provided with a buttress thread, and the locking ring (1-2) is an open ring with a straight or inclined through groove axially opened.

3. An underground injection-production string pre-set working barrel according to claim 2, Its feature is that the upper outer barrel (1-1) is a non-uniform diameter cylindrical body, the upper inner cavity of the upper outer barrel (1-1) is provided with an internal thread for connecting with the completion string, the lower part is a threaded inner cavity, and the middle inner cavity is provided with a locking ring limiting step and an upper outer barrel torque transmission spline (1-11) is provided on the inner circle of the locking ring limiting step; the upper outer barrel torque transmission spline (1-11) can be connected to the locking ring torque transmission spline (1-21) at the top of the ring body of the locking ring (1-2), and after connection, the locking ring (1-2) is exactly located in the locking ring installation cavity between the locking ring limiting step and the lower threaded inner cavity.

4. An underground injection-production string pre-set working barrel according to claim 3, Its feature is that the lower outer barrel (1-3) is a non-uniform diameter cylindrical body, the outer circles at both ends of the lower outer barrel (1-3) are both provided with external threads and can be respectively connected to the internal threads in the threaded inner cavity of the lower part of the upper outer barrel (1-1) and the lower casing thread in the completion string; the upper inner cavity of the lower outer barrel (1-3) is a sealed insertion barrel sealing cavity, and the lower inner cavity is a seal member sealing cavity, and the sealed insertion barrel sealing cavity is a conical cavity.

5. A sealing working barrel used in conjunction with an underground injection-production string pre-set working barrel according to any one of claims 1-4, which is provided with a sealing component. Its feature is that the sealing component includes a sealed insertion barrel (2-7) and a sealing assembly (2-10); an anti-washing hole (2-101) and an anti-washing control hole (2-104) are provided in the inner barrel (2-1); the outer circle of the limiting step three (2-107) in the inner barrel (2-1) is processed with a buttress thread; an upper locking ring (2-2), a sliding barrel (2-3) and a spring (2-4) are sequentially installed above the limiting step three (2-107) from top to bottom; a disc spring (2-5), a sealed insertion barrel (2-7), a middle locking ring (2-8), a sealing assembly (2-10), and a sealing pressing ring (2-11) are sequentially installed below the limiting step three (2-107) from top to bottom; the sealing working barrel (2) is connected to the lower end of the injection-production string and lowered into the pre-set working barrel (1), the inner barrel (2-1) is connected to the buttress thread in the locking ring (1-2), the sealed insertion barrel (2-7) seals the sealed insertion barrel sealing cavity of the lower outer barrel (1-3), and the sealing assembly (2-10) seals the seal member sealing cavity of the lower outer barrel (1-3).

6. The sealing working barrel according to claim 5, It is characterized in that the sealing insertion cylinder (2-7) can be made of rubber or polymer materials, soft metal or shape memory alloy. The outer circle of the lower part of the sealing insertion cylinder (2-7) is a conical outer circle, which cooperates with the sealing insertion cavity of the lower outer cylinder (1-3); a disc spring top ring (2-6) is also installed between the disc spring (2-5) and the sealing insertion cylinder (2-7).

7. The sealed working cylinder according to claim 6 It is characterized in that the inner cylinder (2-1) is a non-uniform diameter cylinder, and injection-production pipe string connection threads and spare part connection threads are respectively arranged at the upper and lower ends of the inner cylinder (2-1); the outer circle of the inner cylinder (2-1) is successively provided with a first limit step (2-103), a second limit step (2-106), a third limit step (2-107), a fourth limit step (2-108) and a fifth limit step (2-110) from top to bottom. The outer circles of the first limit step (2-103), the second limit step (2-106), the third limit step (2-107), the fourth limit step (2-108) and the fifth limit step (2-110) are all precision-machined outer circle surfaces.

8. The sealed working cylinder according to claim 7 It is characterized in that the backwashing hole (2-101) and the backwashing control hole (2-104) are arranged in the first limit step (2-103). The backwashing hole (2-101) is arranged in the outer circle below the injection-production pipe string connection thread, and a first sealing ring groove and a sealing ring are arranged on both the upper and lower sides of the backwashing hole (2-101); the backwashing control hole (2-104) is arranged at the root of the first limit step (2-103), and at least one second sealing ring groove (2-105) is arranged on the outer circle at the top of the second limit step (2-106); the outer diameter of the third limit step (2-107) is the largest, and a buttress thread is machined on this outer circle. A middle locking ring connection thread (2-109) is arranged at the lower end of the outer circle of the fourth limit step (2-108); a spare part connection thread is machined at the lower part of the fifth limit step (2-110).

9. The sealed working cylinder according to claim 8 It is characterized in that the middle locking ring (2-8) is provided with a central hole and an internal thread on its inner circle. After the middle locking ring (2-8) is sleeved outside the inner cylinder (2-1), the internal thread on its inner circle is threadedly connected with the middle locking ring connection thread (2-109); the sealing assembly (2-10) is a combined seal, which at least includes a sealing ring and protective rings made of polytetrafluoroethylene respectively installed on both sides of the sealing ring. The outer diameter of the sealing ring is larger than the inner diameter of the sealing cavity of the sealing part in the lower outer cylinder (1-3); a limit ring (2-9) is also installed between the middle locking ring (2-8) and the sealing assembly (2-10); the sealing pressure ring (2-11) is threadedly connected with the spare part connection thread at the lower part of the fifth limit step (2-110), and a lower pressure ring (2-12) and a soluble plug are also connected below the sealing pressure ring (2-11).

10. The sealed working cylinder according to claim 9 It is characterized in that The inner circle of the sliding cylinder (2-3) is processed with two inner diameters that are smaller at the top and larger at the bottom. The small inner diameter section is installed outside the first limiting step (103) of the inner cylinder (2-1), and the large inner diameter section is installed outside the second limiting step (106). Both inner diameters of the inner circle of the sliding cylinder (2-3) are precision machined surfaces. In the normal working state of the sliding cylinder (2-3), the small inner diameter section blocks the backwashing hole (2-101), and the large inner diameter section communicates with the backwashing control hole (2-104).

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