Low-temperature-resistant self-sealing anchoring tie-back device

Abstract

The invention belongs to the technical field of oil well fracturing transformation, and discloses a low-temperature-resistant self-sealing anchoring tie-back device which comprises a main connector, an inner sealing connector, a slip, a hanging connector and an insertion pipe, and the top end of the inner sealing connector is inserted into the bottom end of the main connector and is in sliding sealing connection with the main connector; the slip is arranged on the outer side of the inner sealing joint and is fixedly connected with the bottom end of the main joint; the top end of the hanging connector is connected with the inner sealing connector, the bottom end of the slip abuts against the top end of the hanging connector, and the bottom end of the hanging connector can be located at the top end of the hanger. The insertion pipe is connected to the bottom end of the hanging connector and can be inserted into the hanger. The axial movement of the insertion pipe can be effectively limited, and the sealing effect is ensured; the slips are opened and anchored under the action of the main joint and the hanging joint, so that the centering position and the stability of the inner sealing joint are ensured; the inner sealing joint and the insertion pipe are in a fixed state under the action of pressure in the axial direction and do not wriggle up and down, the sealing performance is not affected by temperature, and the low-temperature-resistant effect is good.

Description

Technical Field

[0001] The invention relates to the technical field of oil well fracturing transformation, and in particular to a low-temperature resistant self-sealing anchoring tie-back device. Background Art

[0002] In the field of oil and gas field exploitation technology, as production time continues to extend, old blocks of various oil fields generally face problems such as low production and water breakthrough. In recent years, in order to tap the potential of remaining oil reservoirs, improve oil field recovery, reduce drilling operation costs, and reduce comprehensive development costs, for low-yield horizontal wells in low-permeability blocks, with volume fracturing as the goal, a large-displacement double-seal single-card staged fracturing process with integrated application of "comprehensive energy replenishment, dynamic temporary plugging, and synchronous fracturing" has been formed, but there are problems such as long construction period and high construction operation costs. In order to improve fracturing efficiency, shorten construction period, reduce construction costs, and meet the requirements of repeated and efficient staged fracturing technology for horizontal wells, research on bridge-shot repeated fracturing tools and processes after large-size full-diameter wellbore reconstruction has been carried out.

[0003] At present, the casing reconstruction of low-permeability and tight oil and gas horizontal wells in Changqing Oilfield has entered the experimental stage. The main method is to run a φ114.3mm uncoupled casing into a φ139.7mm casing for secondary completion (casing in casing), and then perform bridge-shot continuous fracturing to transform the old well after tieback. Figure 1 As shown, the wellbore reconstruction depth structure includes a tieback casing 1', an insertion head 2', a tieback hanger 3', an outer casing 4', an inner casing 5', a pressure ball seat 6', a first float collar 7', a second float collar 8' and a guide shoe 9', wherein the tieback casing 1' is a 4-1 / 2" pipe, the outer casing 4' and the inner casing 5' are 5-1 / 2" pipe and 4-1 / 2" pipe respectively. Affected by the casing size, the insertion head 2' used at the end of the tieback casing 1' cannot be connected to the hydraulic anchor commonly used in fracturing, and thus the tieback casing 1' cannot be effectively fixed. In particular, after the CO2 pre-fracturing fluid is added, it is subjected to the upward force, and the sealing performance of the insertion pipe of the insertion head 2' during the fracturing process is poor, and the sealing reliability is low.

[0004] In the test construction of repeated fracturing to reform old wells, due to the problem of poor sealing caused by the upward force generated by the pressure, the current method is to press down the pipe string to offset the hanging weight, but the effect is uncertain. It is also uncertain whether the insertion head 2' will still cause pipe string creep due to the pressure fluctuations generated by fracturing. The main difficulties in the current wellbore reconstruction repeated fracturing pipe string are:

[0005] (1) Due to size limitations, conventional anchors cannot be connected, and the tieback device has no anchor. The tieback casing 1' is only supported by its own weight to offset the upward force generated by the high pressure during fracturing construction, resulting in low reliability.

[0006] (2) The back-insertion seal relies only on the sealing rubber ring at the insertion head 2'. The low temperature during CO2 pre-fracturing causes poor sealing reliability.

[0007] (3) When the tieback casing is not heavy enough, the pipe string moves upward under high pressure, affecting the sealing performance.

[0008] At present, there is a great demand for repeated fracturing technology for the transformation of old wells, and the key technology of wellbore reconstruction and tie-back is the core that affects whether the subsequent staged fracturing can be carried out smoothly. Therefore, according to the existing test conditions, the research on low-temperature resistant self-sealing anchor tie-back device is of great significance to solving the problem of repeated fracturing and plug-in sealing in old wells. Summary of the invention

[0009] The purpose of the present invention is to provide a low-temperature resistant self-sealing anchoring tieback device to solve the problem of low sealing reliability caused by low temperature, inability to anchor the tieback device and movement of the pipe column during the fracturing construction of old well reconstruction.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] Low temperature resistant self-sealing anchor tie-back device, including:

[0012] Main connector;

[0013] An inner sealing joint, the top end of which is inserted into the bottom end of the main joint and is connected to the main joint in a sliding and sealing manner;

[0014] Slips, which are arranged on the outside of the inner sealing joint and are fixedly connected to the bottom end of the main joint;

[0015] A hanging joint, the top end of which is connected to the inner sealing joint, the bottom end of the slip abuts against the top end of the hanging joint, and the bottom end of the hanging joint can sit on the top end of the hanger;

[0016] An insertion tube is connected to the bottom end of the hanging joint and can be inserted into the hanger.

[0017] Optionally, the inner wall of the inner sealing joint protrudes from the inner wall of the main joint to form a pressure-bearing surface.

[0018] Optionally, the pressure-bearing surface is arranged to be inclined downward along the outer wall of the inner sealing joint toward the inner wall.

[0019] Optionally, a sliding surface is formed between the top end surface of the hanging joint and the bottom end surface of the slip, and the sliding surface is inclined downward from the inner wall to the outer wall of the hanging joint.

[0020] Optionally, the outer diameter of the hanging joint is greater than the outer diameter of the hanger, and the bottom end surface of the hanging joint can abut against the top end surface of the hanger.

[0021] Optionally, a plurality of first seals are arranged at intervals along the axial direction on the top outer wall of the inner sealing joint, and the first seals can be compressed and sealed between the outer wall of the inner sealing joint and the inner wall of the main joint.

[0022] Optionally, the first sealing member is a fluororubber ring.

[0023] Optionally, a plurality of second sealing members are arranged at intervals along the axial direction on the outer wall of the insertion tube, and the second sealing members are vulcanized on the outer wall of the insertion tube.

[0024] Optionally, the low-temperature resistant self-sealing anchoring tie-back device further comprises a connecting pipe, two ends of which are respectively connected to the main joint and the slip, and the inner sealing joint is slidably connected in the connecting pipe.

[0025] Optionally, the bottom end of the main joint and the top end of the inner sealing joint are both located in the connecting pipe, and the initial distance between the top end of the inner sealing joint and the bottom end of the main joint is not less than the distance difference before and after the slips are opened.

[0026] Beneficial effects of the present invention:

[0027] The low-temperature resistant self-sealing anchoring tieback device of the present invention connects the inner sealing joint and the insertion tube through a hanging joint. When the hanging joint is seated at the top of the hanger, the insertion tube can be inserted into the hanger to achieve positioning and installation, and the hanging joint can effectively limit the axial movement of the insertion tube to ensure the sealing effect; by arranging a slip at the bottom end of the main joint, the bottom end of the slip abuts against the top of the hanging joint, when the main joint is subjected to downward pressure, the slip opens under the action of the main joint and the hanging joint, further fixing the hanging seat at the top of the hanger, while ensuring the center position and stability of the inner sealing joint, further improving the sealing performance. The inner sealing joint and the insertion tube are in a fixed state under the pressure in the axial direction, without up and down creeping, the sealing is not affected by temperature, and the low-temperature resistant effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the wellbore reconstruction depth structure in the prior art;

[0029] Figure 2 is a schematic diagram of the lowering state of the low-temperature resistant self-sealing anchoring tieback device provided by an embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of the working state of the low-temperature resistant self-sealing anchoring tie-back device provided by an embodiment of the present invention;

[0031] Figure 4 yes Figure 3 Schematic diagram of the enlarged structure of area A in the middle.

[0032] In the figure:

[0033] 1', tieback casing; 2', insert head; 3', tieback hanger; 4', outer casing; 5', inner casing; 6', impact ball seat; 7', first floating collar; 8', second floating collar; 9', guide shoe;

[0034] 1. Main joint; 2. Internal sealing joint; 21. First sealing member; 22. Pressure-bearing surface; 3. Slip; 31. Second inclined surface; 4. Hanging joint; 41. First inclined surface; 5. Insertion tube; 51. Second sealing member; 6. Connecting tube. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0036] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0038] In the description of this embodiment, the terms "upper", "lower", "left", "right" and other directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0039] The embodiment of the present invention provides a low temperature resistant self-sealing anchoring tieback device, such as Figure 2-Figure 4 As shown, it includes a main joint 1, an inner sealing joint 2, a slip 3, a hanging joint 4 and an insertion tube 5, wherein the main joint 1, the slip 3, the hanging joint 4 and the insertion tube 5 are arranged in sequence from top to bottom, the main joint 1 is slidingly connected to the inner sealing joint 2, the top end of the inner sealing joint 2 is inserted into the bottom end of the main joint 1 and is slidingly and sealingly connected to the main joint 1; the slip 3 is arranged on the outside of the inner sealing joint 2 and is fixedly connected to the bottom end of the main joint 1; the top end of the hanging joint 4 is connected to the inner sealing joint 2, the bottom end of the slip 3 is abutted against the top end of the hanging joint 4, and the bottom end of the hanging joint 4 can sit on the top end of the hanger; the insertion tube 5 is connected to the bottom end of the hanging joint 4, and the insertion tube 5 can be inserted into the hanger 3.

[0040] Combination Figure 1 The low-temperature resistant self-sealing anchoring tieback device provided in this embodiment is equivalent to the insertion head 2' in the wellbore reconstruction wellbore structure, and is used to solve the problem of poor sealing when the insertion head 2' is inserted into the reconnectable hanger 3'. It can be understood that the low-temperature resistant self-sealing anchoring tieback device in this embodiment is arranged between the tieback casing and the hanger.

[0041] The low-temperature resistant self-sealing anchoring tieback device of the present invention connects the inner sealing joint 2 and the insertion tube 5 through the hanging joint 4, wherein both ends of the hanging joint 4 are internal threads, and the ends of the inner sealing joint 2 and the insertion tube 5 have external threads threadedly connected with the internal threads at both ends of the hanging joint 4. When the hanging joint 4 is seated on the top of the hanger, the insertion tube 5 can be inserted into the hanger to achieve positioning and installation, and during the fracturing process, the hanging joint 4 can abut against the top of the hanger under the action of the upper pressure to prevent the insertion tube 5 from moving up, and at the same time effectively limit the axial downward movement of the insertion tube 5, thereby ensuring that the insertion tube 5 has no axial creeping movement, which is beneficial to ensure the sealing effect of the insertion tube 5. In this embodiment, when in the lowered state, Figure 2 , the outer wall of the slip 3 is flush with the outer wall of the hook joint 4, that is, they have the same outer diameter. Figure 3 , the slip 3 opens to achieve anchoring. It can be understood that by setting the slip 3 at the bottom end of the main joint 1, the slip 3 is serrated, and the bottom end of the slip 3 is against the top of the hanging joint 4. When the main joint 1 is subjected to continuous downward pressure, the slip 3 opens under the action of the main joint 1 and the hanging joint 4, so as to further anchor the hanging seat 4 at the top of the hanger, while ensuring the center position and stability of the inner sealing joint 2, and further improving the sealing performance. The inner sealing joint 2 and the insertion tube 5 are in a fixed state under the pressure in the axial direction, without up and down creeping, the sealing is not affected by temperature, and the low temperature resistance effect is good.

[0042] Optionally, the inner wall of the inner sealing joint 2 protrudes from the inner wall of the main joint 1 to form a pressure-bearing surface 22 .

[0043] like Figure 2 As shown, the top of the inner sealing joint 2 is slidably connected to the inside of the main joint 1, and the outer wall of the inner sealing joint 2 is slidably and sealedly connected to the inner wall of the main joint 1. The purpose of setting the pressure-bearing surface 22 is that when the fracturing fluid is injected into the tube, the fracturing fluid forms a downward pressure on the pressure-bearing surface 22, thereby being able to push the inner sealing joint 2 to have a downward force. Since the inner sealing joint 2 is threadedly connected to the hanging joint 4, and the hanging joint 4 is threadedly connected to the insertion tube 5, that is, the inner sealing joint 2, the hanging joint 4 and the insertion tube 5 form an integrated structure, the top pressure-bearing surface 22 of the inner sealing joint 2 transmits the force to the hanging joint 4 after being subjected to pressure, which is conducive to tightly abutting the hanging joint 4 against the top of the hanger 3, thereby limiting the axial movement of the insertion tube 5, and the sealing reliability is high. Preferably, the inner sealing joint 2 is made of 42CrMo material.

[0044] Optionally, the pressure-bearing surface 22 is arranged to be inclined downward along the outer wall of the inner sealing joint 2 toward the inner wall.

[0045] like Figure 2 As shown, the pressure-bearing surface 22 is an inclined surface relative to the axis of the inner sealing joint 2. An annular pressure-bearing surface 22 with a constricted structure is formed at the top of the inner sealing joint 2, which can achieve the diversion effect on the fracturing fluid, reduce the pressure fluctuation caused by the sudden change of the pipe wall, and avoid the inner sealing joint 2 from being subjected to a large instantaneous impact, which affects the sealing performance.

[0046] Optionally, a sliding surface is formed between the top end surface of the hanging joint 4 and the bottom end surface of the slip 3, and the sliding surface is inclined downward from the inner wall of the hanging joint 4 to the outer wall.

[0047] like Figure 3 and Figure 4 As shown, the top end face of the hook joint 4 has a first inclined surface 41, and the bottom end face of the slip 3 has a second inclined surface 31. The first inclined surface 41 and the second inclined surface 31 abut against each other to form a sliding surface. When the main joint 1 is subjected to force and pushes the slip 3 downward, the slip 3 slides downward along the sliding surface during the opening process to realize the conversion from the lowering state to the working state. It can be understood that the setting of the sliding surface is conducive to the smooth opening and anchoring of the slip 3, and has a guiding effect on the opening direction of the slip 3. It should be noted that the sliding length formed between the first inclined surface 41 and the second inclined surface 31 must ensure that when the slip 3 is in the anchored working state, the slip 3 can still abut against the top of the hook joint 4 for easy recovery.

[0048] Optionally, the outer diameter of the hanging joint 4 is greater than the outer diameter of the hanger, and the bottom end surface of the hanging joint 4 can abut against the top end surface of the hanger.

[0049] like Figure 2 and Figure 3As shown, the internal threads at both ends of the hanging joint 4 are respectively threadedly connected to the internal sealing joint 2 and the insertion tube 5, and the outer diameter of the hanging joint 4 is set to be larger than the outer diameter of the insertion tube 5 and larger than the outer diameter of the hanger, which is conducive to the stable setting of the bottom end face of the hanging joint 4. Generally, the bottom end of the hanging joint 4 abuts against the top end of the hanging tube of the hanger, and the outer wall of the insertion tube 5 is matched with the inner wall of the hanging tube for sleeve connection and sealing.

[0050] Optionally, a plurality of first sealing members 21 are arranged at intervals along the axial direction on the top outer wall of the inner sealing joint 2 , and the first sealing members 21 can be compressed and sealed between the outer wall of the inner sealing joint 2 and the inner wall of the main joint 1 .

[0051] like Figure 2 In this embodiment, the outer wall of the top of the inner sealing joint 2 is processed with multiple annular grooves, and the first sealing member 21 can be arranged in the corresponding grooves to achieve installation and positioning. At the same time, the outer diameter of the first sealing member 21 is greater than the groove depth of the groove, so that the first sealing member 21 can achieve sliding sealing between the main joint 1 and the inner sealing joint 2. Preferably, the first sealing member 21 is a fluoro rubber ring, which has the advantages of a wide operating temperature range and good corrosion resistance.

[0052] Optionally, a plurality of second sealing members 51 are provided at intervals along the axial direction on the outer wall of the insertion tube 5 , and the second sealing members 51 are vulcanized on the outer wall of the insertion tube 5 .

[0053] like Figure 2 As shown, usually, the insert tube 5 adopts a segmented structure, and a segment with the second seal 51 is separately vulcanized to form a sealing structure, and then threadedly connected to another segment, and the second seal 51 is arranged on the outer wall of the insert tube 5 near the bottom end, and the second seal 51 is used to achieve sealing between the insert tube 5 and the inner wall of the suspension tube of the hanger. The second seal 51 is arranged at intervals along the axial direction of the insert tube 5 to form a plurality of sealing segments with a certain length to meet the sealing requirements.

[0054] Optionally, the low-temperature resistant self-sealing anchoring tie-back device further comprises a connecting pipe 6 , two ends of which are respectively connected to the main joint 1 and the slip 3 , and the inner sealing joint 2 is slidably connected in the connecting pipe 6 .

[0055] like Figure 3In order to facilitate the installation of the inner sealing joint 2 and meet the sliding distance requirements of the inner sealing joint 2, the connecting pipe 6 is threadedly connected to the bottom end of the main joint 1 to install the inner sealing joint 2. The top of the connecting pipe 6 has an internal thread, and the bottom end of the main joint 1 has an external thread. The main joint 1 is threadedly connected to the connecting pipe 6, which is convenient for connection and sealing. The cava 3 is arranged at the bottom end of the connecting pipe 6, which is convenient for the installation and replacement of the cava 3. At the same time, by setting the connecting pipe 6, it is convenient to adjust the position of the main joint 1 and the inner sealing joint 2, so that the inner sealing joint 2 meets the limit requirements when sliding, and will not slide out of the connecting pipe 6, nor will it slide excessively and cause damage. It should be supplemented that the above internal threads or external threads all use high-strength tensile and internal pressure resistant marked or non-standard threads to ensure the connection strength.

[0056] Optionally, the bottom end of the main joint 1 and the top end of the inner sealing joint 2 are both located in the connecting pipe 6, and the initial distance between the top end of the inner sealing joint 2 and the bottom end of the main joint 1 is not less than the distance difference before and after the slips 3 are opened.

[0057] like Figure 3 As shown, after the main joint 1 is subjected to downward pressure, the main joint 1 has a downward movement relative to the inner sealing joint 2. Since the inner sealing joint 2 is abutted against the top of the hanger through the hanging joint 4 and remains in a fixed position, the top of the inner sealing joint 2 can limit the main joint 1 from sliding downward excessively and damaging the slip 3. It can be understood that when in the lowered state, the distance between the top of the inner sealing joint 2 and the bottom of the main joint 1 must meet the distance requirement for the slip 3 to be lowered to a sufficient distance to open and anchor, and the automatic retractable function when the slip 3 is lifted after anchoring is considered. The process in which the main joint 1 drives the slip 3 to move downward for anchoring realizes a retractable sealing structure, which can achieve the function of opening and retracting the slip 3, and realize the re-insertion sealing of the inserted pipe 5 without being affected by staged fracturing, which is particularly suitable for repeated fracturing construction during the transformation of old wells.

[0058] Using the low temperature resistant self-sealing anchor tie-back device provided by the present invention, the back-insertion fracturing construction process is as follows:

[0059] First, the low-temperature resistant self-sealing anchor tieback device is set at the bottom end of the tieback casing, and lubricating oil is applied to the outer wall of the insert pipe 5 and its second seal 51. After the insert pipe 5 is lowered along the tieback casing to a certain distance from the top of the hanger, the hanging tube of the hanger is flushed;

[0060] Then insert the insert pipe 5 into the hanging tube so that the bottom end of the hanging joint 4 sits on the top of the hanger. According to the casing hanger, a lengthened casing is made, and the two ends of the lengthened casing are connected to the casing hanger and the tie-back casing respectively.

[0061] Then lower the lengthened casing to the bottom, press down with a force of 10-15 tons, the slip 3 opens, the main joint 1, the inner sealing joint 2 and each pipe section remain centered and are always in a downward pressure state.

[0062] Since the inner diameters of the main joint 1 and the inner sealing joint 2 are different, during the fracturing fluid pressure test, under the action of the pressure difference between the top of the inner sealing joint 2 and the bottom of the insertion tube 5, the inner sealing joint 2, the hanging joint and the insertion tube 5 are always in a downward pressure state, thereby ensuring that the slip 3 is in an open state.

[0063] Finally, the bridge plug is pumped for fracturing construction: during the fracturing construction, the slip 3 is always in an open state to ensure that the pipe string is centered; in the fracturing process, the top of the inner sealing joint 2 is subjected to downward pressure, and even if the pressure fluctuates, it will not affect the sealing of the bottom end of the insertion tube 5. Therefore, the pipe section provided with the second sealing member 51 on the insertion tube 5 is always in a fixed state without moving up and down or creeping, thereby ensuring the sealing reliability of the insertion tube 5.

[0064] The low-temperature resistant self-sealing anchor tieback device of the present invention has high compressive strength and a sealing performance of 70MPa. It is particularly suitable for tieback of a φ114.3mm large-size casing in a 5-1 / 2" small wellbore, which can reduce the construction risk of staged fracturing and improve the construction efficiency of repeated staged fracturing.

[0065] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Low temperature resistant self-sealing anchoring tie-back device, characterized in that: include: Main connector (1); An inner sealing joint (2), the top end of which is inserted into the bottom end of the main joint (1) and is connected to the main joint (1) in a sliding and sealing manner; A slip (3), the slip (3) being arranged on the outer side of the inner sealing joint (2) and fixedly connected to the bottom end of the main joint (1); A hanging joint (4), the top end of the hanging joint (4) is connected to the inner sealing joint (2), the bottom end of the slip (3) is against the top end of the hanging joint (4), and the bottom end of the hanging joint (4) can be seated on the top end of the hanger; An insertion tube (5) is connected to the bottom end of the hanging joint (4), and the insertion tube (5) can be inserted into the interior of the hanger.

2. The low temperature resistant self-sealing anchoring tie-back device according to claim 1, characterized in that: The inner wall of the inner sealing joint (2) protrudes from the inner wall of the main joint (1) to form a pressure-bearing surface (22).

3. The low temperature resistant self-sealing anchoring tie-back device according to claim 2, characterized in that: The pressure-bearing surface (22) is arranged to be inclined downward along the outer wall of the inner sealing joint (2) in a direction toward the inner wall.

4. The low temperature resistant self-sealing anchoring tie-back device according to claim 1, characterized in that: A sliding surface is formed between the top end surface of the hanging joint (4) and the bottom end surface of the slip (3), and the sliding surface is inclined downward from the inner wall of the hanging joint (4) to the outer wall.

5. The low temperature resistant self-sealing anchoring tie-back device according to claim 1, characterized in that: The outer diameter of the hanging joint (4) is greater than the outer diameter of the hanger, and the bottom end surface of the hanging joint (4) can abut against the top end surface of the hanger.

6. The low temperature resistant self-sealing anchoring tie-back device according to claim 1, characterized in that: A plurality of first sealing members (21) are arranged at intervals along the axial direction on the top outer wall of the inner sealing joint (2), and the first sealing members (21) can be compressed and sealed between the outer wall of the inner sealing joint (2) and the inner wall of the main joint (1).

7. The low temperature resistant self-sealing anchoring tie-back device according to claim 6, characterized in that: The first sealing member (21) is a fluororubber ring.

8. The low temperature resistant self-sealing anchoring tie-back device according to claim 1, characterized in that: A plurality of second sealing members (51) are arranged at intervals along the axial direction on the outer wall of the insertion tube (5), and the second sealing members (51) are vulcanized on the outer wall of the insertion tube (5).

9. The low temperature resistant self-sealing anchoring tie-back device according to claim 1, characterized in that: It also comprises a connecting pipe (6), the two ends of which are respectively connected to the main joint (1) and the slip (3), and the inner sealing joint (2) is slidably connected inside the connecting pipe (6).

10. The low temperature resistant self-sealing anchoring tie-back device according to claim 9, characterized in that: The bottom end of the main joint (1) and the top end of the inner sealing joint (2) are both located in the connecting pipe (6), and the initial distance between the top end of the inner sealing joint (2) and the bottom end of the main joint (1) is not less than the distance difference before and after the slip (3) is opened.

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