A liner anticorrosion tubing for oil well production

Abstract

The application provides a corrosion-resistant inner lining pipe for oil extraction of an oil well, and relates to the technical field of oil extraction tools, which comprises an outer base pipe, the outer surface of the outer base pipe is provided with a base pipe thread taper with a taper structure at both ends, a sleeve connector is connected to the end of the outer base pipe, both ends of the inner taper of the sleeve connector are provided with an inner taper, the inner taper is spirally connected with the base pipe thread taper, and the outer base pipe is internally provided with a corrosion-resistant inner lining pipe, which solves the problem that although the existing structure can realize mechanical connection of the outer wall of the pipeline, it lacks a matching inner lining sealing butt joint scheme, so that oil is easy to seep into the inner lining joint gap and corrode the base pipe wall; meanwhile, the existing heat preservation structure is also easy to be soaked or corroded by oil liquid in such leakage, so that the heat preservation performance is reduced, and as the lifting height of the produced liquid increases, the environmental temperature decreases, and for high-wax crude oil, once the temperature is not maintained, the crude oil will be difficult to be extracted to the ground due to the sudden increase in viscosity and the deterioration of flowability.

Description

Technical Field

[0001] This invention relates to the field of oil extraction tools, and more particularly to a corrosion-resistant lined tubing for oil well production. Background Technology

[0002] In oil extraction, tubing, placed inside casing, serves as the core channel for lifting crude oil from the well to the surface. Currently, oilfields commonly use metal tubing, with individual tubes connected by external threads at one end and couplings at the other, forming a continuous pipeline when lowered into the well. To resist corrosion from acidic downhole media, prevent oil leaks, production stoppages, and safety accidents caused by perforation, and ensure long-term stable production of oil wells, the use of corrosion-resistant lined tubing has become a crucial measure.

[0003] Statistics show that failures at the threaded joints of oil pipes account for 80% of all oil pipe failures. This is because while the existing structure can achieve mechanical connection to the outer wall of the pipe, it lacks a matching inner lining sealing solution, which makes it easy for oil to seep in through the gaps in the inner lining joint and corrode the base pipe wall. At the same time, the existing insulation structure is also easily soaked or corroded by oil in such leaks and fails, which reduces its insulation performance. As the height of the produced fluid increases and the ambient temperature decreases, for high waxy crude oil, once the temperature is not maintained, the crude oil will be difficult to extract to the surface due to a sudden increase in viscosity and deterioration in fluidity. Summary of the Invention

[0004] This invention provides an internally lined anti-corrosion tubing for oil well production, in order to solve the problems mentioned in the background art.

[0005] This invention provides an anti-corrosion lined tubing for oil well production, specifically comprising: an outer base pipe, wherein both ends of the outer surface of the outer base pipe are respectively provided with tapered threaded conical surfaces; a sleeve connector is connected to the end of the outer base pipe, and both ends of the sleeve connector are provided with inner conical surfaces, which are spirally connected to the threaded conical surfaces of the base pipe; an anti-corrosion liner is placed inside the outer base pipe; and a reinforcing support layer wound into a cylindrical structure surrounds the anti-corrosion liner; the reinforcing support layer is wound and installed between the reinforcing support layer and the inner wall of the outer base pipe. It has an insulation layer and corrosion-resistant inner lining pipe with inner lining sealing flanges processed at both ends. The outer surface of the inner lining sealing flange is attached to the inner surface of the outer base pipe. An upper sealing sleeve is inserted into the upper end of the inner base pipe and a lower sealing sleeve is inserted into the lower end of the inner base pipe. The upper sealing sleeve is tightly attached to the inner surface of the upper inner lining sealing flange, and the lower sealing sleeve is tightly attached to the inner surface of the lower inner lining sealing flange. In the two outer base pipes that are connected, the upper sealing sleeve of the lower outer base pipe is connected to the lower sealing sleeve of the upper outer base pipe.

[0006] Furthermore, a ring-shaped sleeve sealing ring is fixedly connected to the middle part of the inner surface of the sleeve connector.

[0007] Furthermore, the lower edge of the upper sealing sleeve is fixedly connected to an upper elastic pressure ring, the outer surface of the upper elastic pressure ring is attached to the inner surface of the inner lining sealing fold, the upper elastic pressure ring has six upper pressure ring through grooves distributed circumferentially on the ring wall, and a tapered shrinkage transition structure is provided between the upper elastic pressure ring and the upper sealing sleeve.

[0008] Furthermore, the lower edge of the inner surface of the upper elastic pressure ring is provided with an upper limit inner flange, and the inclined surface of the upper limit inner flange faces inward and upward.

[0009] Furthermore, the outer wall of the outer conical structure of the upper sealing sleeve is fitted with an annular sealing ring, which is tightly fitted with the outer edge of the inner lining sealing flange and the inner wall of the outer base tube.

[0010] Furthermore, a lower elastic pressure ring is fixedly connected to the upper edge of the lower sealing sleeve. The outer surface of the lower elastic pressure ring is attached to the inner wall of the inner lining sealing fold at the lower end of the anti-corrosion inner lining tube. Six lower pressure ring through grooves are evenly distributed around the ring wall of the lower elastic pressure ring. A tapered shrinkage transition structure is provided between the lower elastic pressure ring and the lower sealing sleeve.

[0011] Furthermore, the upper edge of the inner wall of the lower elastic pressure ring is provided with a lower limiting inner flange, the inclined surface of the lower limiting inner flange faces inward and downward, and the conical part of the lower sealing sleeve is fitted with an inner filling sealing ring, which tightly fits the lower edge of the inner wall of the outer base tube and the inner lining sealing flange.

[0012] Furthermore, the upper outer edge of the upper sealing sleeve is provided with an outer ring opening, and the lower inner edge of the lower sealing sleeve is provided with an inner ring groove. The outer ring opening and the inner ring groove are mated together, and a curved sealing ring is tightly provided in the joint between the two.

[0013] Furthermore, both the upper and lower sealing sleeves are equipped with limiting push rings, and the limiting push rings are fixedly connected to tightening wedge rings.

[0014] Furthermore, the outer wall edge of the tightening wedge ring is provided with a wedge ring limiting groove, and the two tightening wedge rings are respectively tightly fitted to the upper elastic pressure ring and the lower elastic pressure ring, and the two wedge ring limiting grooves are respectively inserted into the upper limiting inner flange and the lower limiting inner flange.

[0015] This invention provides an internally lined anti-corrosion tubing for oil well production, which has the following beneficial effects: This invention constructs multiple axial and radial seals inside the oil pipe joint by setting an upper sealing sleeve and a lower sealing sleeve, and setting a curved sealing ring at the joint of the two, combined with the inner lining sealing folded edge structure, as well as the sealing functions of the ring sealing ring and the inner filling sealing ring. This effectively blocks the path of crude oil seeping into the base pipe wall and significantly reduces the corrosion risk at the threaded joint.

[0016] Furthermore, by installing a spiral insulation layer between the outer base pipe and the anti-corrosion inner liner, a thermal insulation effect can be achieved. This prevents the oil inside the tubing from rapidly cooling due to the external low-temperature environment as the elevation increases during the extraction process, which would lead to a sudden increase in viscosity, deterioration of fluidity, and difficulty in extraction to the surface. A reinforced support layer is used for protection, supporting the inner wall of the reinforced support layer. This prevents the insulation layer from being squeezed due to changes in the pressure inside the tubing, avoiding deformation after compression and reducing the insulation effect. Maintaining a stable and reliable insulation effect effectively reduces heat loss from the wellbore, maintains the crude oil temperature, and thus ensures the fluidity of high-wax crude oil during the lifting process, improving extraction efficiency.

[0017] Furthermore, this invention utilizes the cooperation of an elastic pressure ring with an upper limit inner flange and a lower limit inner flange, and a tightening wedge ring. The upper limit inner flange and the lower limit inner flange are inserted into the wedge ring limiting groove, maintaining a tight fit between the tightening wedge ring and the elastic pressure ring. The upper and lower elastic pressure rings are pushed outward, making them fit tightly against the inner lining sealing edge and applying continuous pushing against the inner wall of the outer base tube. This ensures a tight fit between the anti-corrosion inner lining tube and the inner wall of the outer base tube, maintaining a reliable seal. This achieves reliable anchoring and stress relief at the end of the anti-corrosion inner lining tube, preventing the inner lining tube from coming out under fluid pressure and adapting to expansion and contraction caused by temperature changes, thus improving the stability and service life of the overall structure. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0019] The accompanying drawings described below are only related to some embodiments of the invention and are not intended to limit the invention.

[0020] In the attached diagram: Figure 1 A schematic diagram of the overall structure of this application is shown; Figure 2 A schematic diagram of the sleeve connector of this application is shown; Figure 3 This diagram illustrates the structure of the two outer base tubes when they are separated according to this application. Figure 4 A schematic diagram of the anti-corrosion lining pipe of this application is shown; Figure 5 This diagram shows the structural layout of the anti-corrosion lining pipe, insulation layer, and reinforced support layer of this application. Figure 6 This diagram shows the structure of the upper and lower sealing sleeves in the mating state of this application; Figure 7 This diagram shows the structure of the upper sealing sleeve and the lower sealing sleeve in the separated state of this application; Figure 8 This application shows Figure 2 A magnified view of a portion of point A in the middle; Figure 9 This application shows Figure 2 A magnified view of a portion of point B in the middle; Figure 10 This application shows Figure 3 A magnified view of a portion of point C in the middle; Figure 11 This application shows Figure 4 A magnified view of a portion of point D.

[0021] Figure label: 1. Outer base tube; 101. Base tube threaded tapered surface; 2. Sleeve connector; 201. Inner tapered surface; 202. Sleeve sealing ring; 3. Corrosion-resistant inner lining tube; 301. Inner lining sealing flange; 4. Insulation layer; 5. Reinforced support layer; 6. Upper sealing sleeve; 601. Upper elastic pressure ring; 602. Upper pressure ring through groove; 603. Upper limit inner flange; 604. Ring seal; 605. Outer ring opening; 7. Lower sealing sleeve; 701. Lower elastic pressure ring; 702. Lower pressure ring through groove; 703. Lower limit inner flange; 704. Inner filling seal; 705. Inner ring groove; 8. Limiting push ring; 801. Tightening wedge ring; 802. Wedge ring limiting ring groove; 9. Curved sealing ring. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: Please refer to Figures 1 to 11 : This invention proposes an anti-corrosion lined tubing for oil well production, comprising: an outer base pipe 1, with tapered threaded conical surfaces 101 at both ends of the outer surface of the outer base pipe 1; a sleeve connector 2 connected to the end of the outer base pipe 1; and inner conical surfaces 201 at both ends of the sleeve connector 2, which are spirally connected to the threaded conical surfaces 101 of the base pipe; an anti-corrosion liner 3 is placed inside the outer base pipe 1, and the anti-corrosion liner 3 is surrounded by a coiled... A cylindrical reinforcing support layer 5 is formed, and an insulation layer 4 is wound and installed between the reinforcing support layer 5 and the inner wall of the outer base pipe 1. Both ends of the corrosion-resistant inner lining pipe 3 are machined with inner lining sealing flanges 301. The outer surface of the inner lining sealing flanges 301 is fitted to the inner surface of the outer base pipe 1. An upper sealing sleeve 6 is inserted into the upper part of the inner surface of the outer base pipe 1, and a lower sealing sleeve 7 is inserted into the lower part of the inner surface of the outer base pipe 1. The upper sealing sleeve 6 is tightly fitted to the inner surface of the upper inner lining sealing flange 301. The lower sealing sleeve 7 fits tightly against the inner surface of the inner lining sealing flange 301 located at the lower end. Among the two outer base pipes 1 that are connected, the upper sealing sleeve 6 of the lower outer base pipe 1 is connected to the lower sealing sleeve 7 of the upper outer base pipe 1. Inside the outer base pipe 1, there is an anti-corrosion inner lining pipe 3, a heat insulation layer 4, and a reinforced support layer 5, which can play a role in heat insulation. This prevents the oil inside the tubing from cooling rapidly due to the low temperature environment when the height increases during the extraction process, which would lead to a sudden increase in viscosity and deterioration in fluidity, making it difficult to extract to the surface. The reinforced support layer 5 is used for protection and supports the inner wall of the reinforced support layer 5. This can prevent the heat insulation layer 4 from being squeezed due to changes in the pressure inside the tubing, and prevent the heat insulation layer 4 from deforming after being squeezed, thus reducing the heat insulation effect. This maintains a stable and reliable heat insulation effect, which can effectively reduce the heat loss of the wellbore, maintain the temperature of crude oil, and thus ensure the fluidity of high wax crude oil during the lifting process.

[0024] In this embodiment, a ring-shaped sleeve sealing ring 202 is fixedly connected to the middle part of the inner surface of the sleeve connector 2. When the two outer base pipes 1 are in the docking state, the end faces of the two outer base pipes 1 are tightly fitted with the sleeve sealing ring 202, which improves the sealing between the two pipe sections and prevents crude oil from leaking through the end of the outer base pipe 1.

[0025] In this embodiment, an upper elastic pressure ring 601 is fixedly connected to the lower edge of the upper sealing sleeve 6. The outer surface of the upper elastic pressure ring 601 is in contact with the inner surface of the inner lining sealing flange 301. Six upper pressure ring through grooves 602 are distributed circumferentially on the ring wall of the upper elastic pressure ring 601. A tapered shrinkage transition structure is provided between the upper elastic pressure ring 601 and the upper sealing sleeve 6. An upper limit inner flange 603 is protruding from the lower edge of the inner surface of the upper elastic pressure ring 601. The inclined surface of the upper limit inner flange 603 faces inward and upward. When the limiting push ring 8 is pushed into the upper elastic pressure ring 601, its end edge slides and connects with the inclined surface of the upper limit inner flange 603. When the upper limit inner flange 603 is flush with the wedge ring limiting groove 802, it is inserted to effectively lock the limiting push ring 8 and prevent the limiting push ring 8 from sliding. Under normal conditions, the upper elastic pressure ring 601 is slightly curved inward, which facilitates its insertion into the inner lining sealing flange 301 during the assembly process.

[0026] In this embodiment, an annular sealing ring 604 is fitted onto the outer wall of the outer conical structure of the upper sealing sleeve 6. The annular sealing ring 604 is tightly fitted with the outer edge of the inner lining sealing flange 301 and the inner wall of the outer base tube 1. The annular sealing ring 604 seals the upper sealing sleeve 6 and the outer base tube 1 to prevent crude oil from overflowing.

[0027] In this embodiment, a lower elastic pressure ring 701 is fixedly connected to the upper edge of the lower sealing sleeve 7. The outer surface of the lower elastic pressure ring 701 is attached to the inner wall of the inner lining sealing flange 301 located at the lower end of the anti-corrosion inner lining tube 3. Six lower pressure ring through grooves 702 are evenly distributed around the circumference of the lower elastic pressure ring 701. The lower pressure ring through grooves 702 allow the lower elastic pressure ring 701 to increase its inner diameter and expand and deform when subjected to internal expansion. A tapered shrinkage transition structure is provided between the lower elastic pressure ring 701 and the lower sealing sleeve 7. A lower limiting inner flange 703 is protruding from the upper edge of the inner wall of the lower elastic pressure ring 701. The inclined surface of the lower limiting inner flange 703 faces inward and downward. An inner filling sealing ring 704 is sleeved on the tapered part of the lower sealing sleeve 7. The inner filling sealing ring 704 is tightly attached to the inner wall of the outer base tube 1 and the lower edge of the inner lining sealing flange 301 to achieve a sealing effect.

[0028] In this embodiment, the upper outer edge of the upper sealing sleeve 6 is provided with an outer ring opening 605, and the lower inner edge of the lower sealing sleeve 7 is provided with an inner ring groove 705. The outer ring opening 605 and the inner ring groove 705 are connected, and a curved sealing ring 9 is tightly provided in the joint between the two. Through the multiple sealing structure of the curved sealing ring 9, the ring sealing ring 604, and the inner filling sealing ring 704, the sealing between different inner lining layers inside the pipeline is improved.

[0029] In this embodiment, both the upper sealing sleeve 6 and the lower sealing sleeve 7 are equipped with a limiting push ring 8. The limiting push ring 8 is fixedly connected to a shrinking wedge ring 801. The outer surface of the shrinking wedge ring 801 has a conical structure, which causes it to expand and deform outward during the insertion of the upper elastic pressure ring 601 or the lower elastic pressure ring 701, thereby strengthening the adhesion strength between the inner lining sealing fold 301 and the inner wall of the outer base tube 1.

[0030] In Example 2, based on Example 1, a wedge ring limiting groove 802 is provided on the outer edge of the tightening wedge ring 801. The two tightening wedge rings 801 are respectively tightly fitted to the upper elastic pressure ring 601 and the lower elastic pressure ring 701. The two wedge ring limiting grooves 802 are respectively inserted into the upper limiting inner flange 603 and the lower limiting inner flange 703. Under normal conditions, both the lower elastic pressure ring 701 and the upper elastic pressure ring 601 are slightly curved inward to facilitate their insertion into the inner lining sealing flange 301 during the insertion of the outer base tube 1, where they fit against the inner surface of the inner lining sealing flange 301. Then, the limiting push ring 8 is pushed inward by a hydraulic device, causing the tightening wedge ring 801 to enter the upper elastic pressure ring 601. 1 or lower elastic pressure ring 701, and under continuous pushing action, the upper elastic pressure ring 601 or lower elastic pressure ring 701 expands and deforms outward, tightly pressing the inner lining sealing fold 301 part, effectively sealing the insulation layer 4 and the reinforced support layer 5 through the anti-corrosion inner lining tube 3, and when the wedge ring limiting ring groove 802 is flush with the outer ring opening 605 and the inner ring connecting groove 705, under the elastic action, the wedge ring limiting ring groove 802 engages with the outer ring opening 605 and the inner ring connecting groove 705, realizing the axial locking of the limiting push ring 8, thereby maintaining the continuous expansion and support of the upper elastic pressure ring 601 and lower elastic pressure ring 701, and maintaining the tight fit between the inner lining sealing fold 301 and the outer base tube 1.

[0031] The working principle of this embodiment is as follows: First, the reinforcing support layer 5 is rolled up and wrapped around the outside of the anti-corrosion inner lining tube 3, so that it fits the anti-corrosion inner lining tube 3. Then, the insulation layer 4 is rolled up and wrapped around the reinforcing support layer 5. The anti-corrosion inner lining tube 3, the insulation layer 4, and the reinforcing support layer 5 are installed into the outer base tube 1. The upper sealing sleeve 6 and the lower sealing sleeve 7 are inserted into both ends of the outer base tube 1. The limiting push ring 8 is pushed in through the opening. The limiting push ring 8 is pushed inward by the hydraulic device, so that the tightening wedge ring 801 enters the upper elastic pressure ring 601 or the lower elastic pressure ring 701. Under the continuous pushing action, the upper elastic pressure ring 601 or the lower elastic pressure ring 701 expands and deforms outward, tightly pressing the inner lining sealing folded edge 301. The insulation layer 4 and the reinforcing support layer 5 are then sealed by the anti-corrosion inner lining tube 3. The inner liner 3 provides effective sealing. When the two tubings are connected through the sleeve connector 2, the outer base pipe 1 achieves mechanical connection through the engagement of the base pipe thread tapered surface 101 and the inner tapered surface 201. At the same time, the upper sealing sleeve 6 and the lower sealing sleeve 7 approach and press against each other under axial pressure, so that the curved sealing ring 9 fits tightly against the outer ring opening 605 and the inner ring groove 705, forming a radial seal. The curved sealing ring 9, the ring sealing ring 604, and the inner filling sealing ring 704 together constitute multiple axial sealing barriers, effectively preventing crude oil from seeping into the pipe wall gaps. The insulation layer 4 remains stable under the protection of the reinforced support layer 5, avoiding excessive oil pressure that could cause it to deform and reduce the insulation effect, thus mitigating wellbore heat loss and ensuring crude oil fluidity.

[0032] The following points should be noted in this article: 1. The accompanying drawings of the embodiments disclosed herein only relate to the structures involved in the embodiments disclosed herein; other structures can be referred to in general design.

[0033] 2. Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0034] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A corrosion-resistant lined tubing for oil well production, comprising: The outer base tube (1) is characterized in that the outer surface of the outer base tube (1) is provided with a tapered pipe thread tapered surface (101) with a tapered structure at both ends, and a sleeve connector (2) is connected to the end of the outer base tube (1). The sleeve connector (2) is provided with an inner tapered surface (201) at both ends inside, and the inner tapered surface (201) is spirally connected to the tapered pipe thread tapered surface (101). The outer base tube (1) is provided with an anti-corrosion inner liner tube (3), and the anti-corrosion inner liner tube (3) is surrounded by a reinforced support layer (5) wound into a cylindrical structure. An insulation layer (4) is wound and installed between the reinforced support layer (5) and the inner wall of the outer base tube (1). The anti-corrosion inner liner (3) has inner liner sealing flanges (301) processed at both ends. The outer surface of the inner liner sealing flanges (301) is attached to the inner surface of the outer base pipe (1). An upper sealing sleeve (6) is inserted into the upper end of the inner layer of the outer base pipe (1), and a lower sealing sleeve (7) is inserted into the lower end of the inner layer of the outer base pipe (1). The upper sealing sleeve (6) is tightly attached to the inner surface of the inner liner sealing flange (301) located at the upper end, and the lower sealing sleeve (7) is tightly attached to the inner surface of the inner liner sealing flange (301) located at the lower end. Among the two outer base pipes (1) that are joined together, the upper sealing sleeve (6) of the lower outer base pipe (1) is attached to the upper outer base pipe (1). The lower sealing sleeve (7) of the base tube (1) is connected to the upper sealing sleeve (6). The lower edge of the upper sealing sleeve (6) is fixedly connected to an upper elastic pressure ring (601). The lower edge of the inner surface of the upper elastic pressure ring (601) is provided with an upper limit inner flange (603). The upper edge of the lower sealing sleeve (7) is fixedly connected to a lower elastic pressure ring (701). The upper edge of the inner wall of the lower elastic pressure ring (701) is provided with a lower limit inner flange (703). The upper outer edge of the upper sealing sleeve (6) is provided with an outer ring opening (605). The lower inner lower edge of the lower sealing sleeve (7) is provided with an inner ring groove (705). The collar opening (605) is connected to the inner ring groove (705), and a curved sealing ring (9) is tightly provided in the joint between the two. The upper sealing sleeve (6) and the lower sealing sleeve (7) are both equipped with limit push rings (8). The limit push rings (8) are fixedly connected to the shrinking wedge rings (801). The outer edge of the shrinking wedge ring (801) is provided with a wedge ring limiting groove (802). The two shrinking wedge rings (801) are tightly fitted to the upper elastic pressure ring (601) and the lower elastic pressure ring (701) respectively. The two wedge ring limiting grooves (802) are respectively inserted into the upper limiting inner flange (603) and the lower limiting inner flange (703).

2. The anti-corrosion lined tubing for oil well production according to claim 1, characterized in that, The sleeve connector (2) has a ring-shaped sleeve sealing ring (202) fixedly connected to the middle part of the inner surface of the sleeve connector (2).

3. The anti-corrosion lined tubing for oil well production according to claim 1, characterized in that, The outer surface of the upper elastic pressure ring (601) is attached to the inner surface of the inner lining sealing flange (301). The upper elastic pressure ring (601) has six upper pressure ring through grooves (602) distributed circumferentially on the ring wall. An upper conical shrinkage transition structure is provided between the upper elastic pressure ring (601) and the upper sealing sleeve (6).

4. The anti-corrosion lined tubing for oil well production according to claim 1, characterized in that, The inclined surface of the upper limit inner flange (603) faces inward and upward.

5. The anti-corrosion lined tubing for oil well production according to claim 1, characterized in that, The outer wall of the upper sealing sleeve (6) is fitted with an annular sealing ring (604) on the outer conical structure. The annular sealing ring (604) is tightly fitted with the outer edge of the inner lining sealing fold (301) and the inner wall of the outer base tube (1).

6. The anti-corrosion lined tubing for oil well production according to claim 1, characterized in that, The outer surface of the lower elastic pressure ring (701) is attached to the inner wall of the inner lining sealing flange (301) located at the lower end of the anti-corrosion inner lining tube (3). The lower elastic pressure ring (701) has six lower pressure ring through grooves (702) evenly distributed around its ring wall. A lower conical shrinkage transition structure is provided between the lower elastic pressure ring (701) and the lower sealing sleeve (7).

7. The anti-corrosion lined tubing for oil well production according to claim 1, characterized in that, The inclined surface of the lower limit inner flange (703) faces inward and downward, and the conical part of the lower sealing sleeve (7) is fitted with an inner filling sealing ring (704). The inner filling sealing ring (704) fits tightly against the inner wall of the outer base tube (1) and the lower edge of the inner lining sealing flange (301).

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