A casing telescoping compensation device

Abstract

The present application belongs to the technical field of cementing tools for oil and natural gas, and particularly relates to a casing telescopic compensation device. The present application comprises a center pipe group and an outer pipe group sleeved on the center pipe group; the initial connection state between the center pipe group and the outer pipe group is a fixed connection state; a containing space is formed between the center pipe group and the outer pipe group, and a temperature memory alloy is arranged in the containing space; the temperature memory alloy is configured to be able to push the center pipe group and the outer pipe group to relatively displace, so that the center pipe group and the outer pipe group are changed from the fixed connection state to a free state capable of relatively sliding along the axial direction of the center pipe group. Through the relative sliding of the center pipe group and the outer pipe group, the present application realizes the compensation for the length change of the casing; when the length of the casing increases, the present application shortens the length through the sliding of the center pipe group and the outer pipe group; when the length of the casing decreases, the present application increases the length through the sliding of the center pipe group and the outer pipe group, and further controls the stress change of the casing to prevent the casing from being damaged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas cementing tools, and particularly relates to a casing telescopic compensation device. BACKGROUND

[0002] Affected by the change of downhole temperature environment, the casing deforms with the change of temperature, which leads to the damage of the casing caused by the deformation of the casing. In recent years, with the wide application of the casing in cementing, the damage of the casing caused by the change of downhole temperature has a more and more serious trend. In order to prevent the production slowdown or the casing damage, a lot of work has been done in the completion process technical measures, and certain results have been achieved. However, due to the process, tools and special geological conditions, the process technical measures are not implemented in place, which leads to the increase of the casing damage wells by more than 10%. The casing is damaged or deformed due to the axial change of thermal stress, which affects the later production operation. SUMMARY

[0003] The present application aims to provide a casing telescopic compensation device to relieve the thermal stress deformation of the casing string, control the stress value in the casing within the yield limit range through axial telescopic adjustment, and reduce the casing damage.

[0004] In order to solve the above technical problems, the technical scheme provided by the present application is as follows:

[0005] A casing telescopic compensation device comprises a center pipe group and an outer pipe group sleeved on the center pipe group; a containing space is formed between the center pipe group and the outer pipe group, and a temperature memory alloy is arranged in the containing space; the temperature memory alloy is configured to push the center pipe group and the outer pipe group to relatively displace, so that the center pipe group and the outer pipe group change from a fixed connection state to a free state capable of relatively sliding along the axial direction of the center pipe group.

[0006] Further, the center pipe group comprises a center pipe, and a limiting boss is arranged at the middle part of the outer circle of the center pipe; the outer side of the limiting boss is in contact with the inner side of the outer pipe group.

[0007] Further, the center pipe group further comprises a lower joint, and the lower joint is sleeved on the center pipe and is screwed with the center pipe.

[0008] Further, the outer pipe group comprises a pressure ring, and the pressure ring comprises a main body part abutting against the top end face of the center pipe and a extending-in part extending into the containing space; the extending-in part is sleeved on the center pipe and is in sliding connection with the center pipe.

[0009] Further, the outer pipe group further comprises an outer pipe, and the outer pipe is sleeved on the center pipe; the inner circle of the outer pipe, the outer circle of the center pipe, the limiting boss and the pressure ring form the containing space.

[0010] Further, the outer tube group further comprises an upper joint, the upper joint is sleeved on the outer tube and is screwed with the outer tube, and a buffer ring is arranged between the lower end of the upper joint and the compression ring.

[0011] Further, the outer tube group further comprises a variable joint, the variable joint comprises an upper joint and a lower joint, an inner circle at the joint of the upper joint and the lower joint is provided with a first boss, the upper joint is sleeved on the lower end of the outer tube and is screwed with the outer tube, and the first boss abuts against the lower end of the outer tube.

[0012] Further, the outer tube group further comprises a limiting ring, the limiting ring is arranged below the first boss, and a space between the limiting ring and the limiting boss is a sliding space of the central tube group and the outer tube group.

[0013] Further, the outer tube group further comprises a compression ring, the compression ring is sleeved on the lower joint and is screwed with the lower joint, the compression ring is provided with a second stepped surface, the second stepped surface is in contact with the lower end of the limiting ring, and the position of the limiting ring is limited.

[0014] Further, the outer tube group further comprises a high-temperature-resistant sand prevention ring, and the upper end of the high-temperature-resistant sand prevention ring is connected with the lower end of the compression ring.

[0015] The technical effects that can be achieved by the present application in combination with the above technical solutions are as follows:

[0016] The casing telescopic compensation device provided by the present application comprises a central tube group and an outer tube group sleeved on the central tube group, the initial connection state between the central tube group and the outer tube group is a fixed connection state, a containing space is formed between the central tube group and the outer tube group, a temperature memory alloy is arranged in the containing space, and the temperature memory alloy is configured to be capable of pushing the central tube group and the outer tube group to relatively displace, so that the central tube group and the outer tube group are changed from the fixed connection state to a free state capable of relatively sliding along the axial direction of the central tube group.

[0017] It should be noted that the casing telescopic compensation device provided by the present application is arranged in the middle of a casing, and divides the casing into an upper casing and a lower casing, the lower end of the central tube group is connected with the lower casing, and the upper end of the outer tube group is connected with the upper casing. Hereinafter, the end of the central tube group connected with the lower casing and the end of the outer tube group connected with the upper casing are named as connection ends.

[0018] Because the sleeve expansion compensation device provided by this invention allows the central tube assembly and outer tube assembly to change from a fixed connection state to a free state where they can slide relative to each other along the axis of the central tube assembly after relative displacement caused by the temperature memory alloy, the length of the sleeve expansion compensation device can freely vary within a certain range. Specifically, when the temperature rises, the sleeve length increases, reducing the distance between the connecting ends of the upper and lower sleeves, thus compressing the sleeve expansion compensation device; when the temperature decreases, the sleeve length decreases, increasing the distance between the connecting ends of the upper and lower sleeves, thus stretching the sleeve expansion compensation device. Therefore, by compensating for the change in sleeve length through the relative sliding of the central tube assembly and outer tube assembly, the internal stress of the sleeve caused by temperature-induced length changes is reduced, keeping the internal stress value of the sleeve within the yield limit range and reducing sleeve damage. This avoids the situation where, when the length of a single sleeve changes due to temperature variations, the fixed ends prevent the length change from being obstructed, leading to an increase in internal stress in the sleeve. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a half-sectional schematic diagram of the sleeve expansion compensation device provided in an embodiment of the present invention;

[0021] Figure 2 for Figure 1 Cross-sectional view of intermediate pressure ring 400;

[0022] Figure 3 for Figure 1 Cross-sectional view of medium transformer connector 700;

[0023] Figure 4 for Figure 1 Cross-sectional view of the medium pressure cap ring 900;

[0024] Figure 5 Bit Figure 1 Cross-sectional view of the lower connector 1300.

[0025] Icon: 100 - upper joint; 200 - outer tube; 300 - cushion ring; 400 - compression ring; 500 - center tube; 600 - temperature memory alloy; 700 - variable buckle joint; 800 - limiting ring; 900 - compression cap ring; 1000 - composite sealing ring; 1100 - pin; 1200 - high-temperature-resistant sand prevention ring; 1300 - lower joint; 410 - main body part; 420 - extension part; 510 - limiting boss; 710 - upper joint; 720 - lower joint; 730 - first step surface; 740 - first boss; 910 - second step surface; 920 - first sealing groove; 1310 - second sealing groove; 1320 - third step surface. DETAILED DESCRIPTION

[0026] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0028] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0029] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0030] In addition, the terms "horizontal", "vertical", "overhang", and the like do not mean that the components must be absolutely horizontal or overhanging, but can be slightly inclined. For example, "horizontal" only means that it is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0031] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The following examples and features in the examples can be combined with each other without conflict.

[0033] Affected by the change of downhole temperature environment, the casing deforms with the change of temperature, which causes the casing deformation and damage. In recent years, with the wide application of casing in cementing, the casing damage caused by the change of downhole temperature has become more and more serious. In order to prevent production slowdown or casing damage, a lot of work has been done in the completion process technical measures, and certain results have been achieved. However, due to the process, tools and special geological conditions, the process technical measures are not implemented in place, which leads to the increase of casing damage wells by more than 10%. The casing is damaged by the axial change of thermal stress, which leads to the damage of thread or the deformation of casing, and affects the later production operation.

[0034] Therefore, the present application provides a casing expansion compensation device, which comprises a central pipe group and an outer pipe group sleeved on the central pipe group; the initial connection state between the central pipe group and the outer pipe group is a fixed connection state; a containing space is formed between the central pipe group and the outer pipe group, and a temperature memory alloy 600 is arranged in the containing space; the temperature memory alloy 600 is configured to push the central pipe group and the outer pipe group to relatively displace, so that the central pipe group and the outer pipe group change from the fixed connection state to a free state capable of relatively sliding along the axial direction of the central pipe group.

[0035] It should be noted that: the casing expansion compensation device provided by the present application is arranged in the middle of the casing, which divides a casing into an upper casing and a lower casing. The lower end of the central pipe group is connected with the lower casing, and the upper end of the outer pipe group is connected with the upper casing. The end of the central pipe group connected with the lower casing and the end of the outer pipe group connected with the upper casing are named as connection ends.

[0036] Because the sleeve expansion compensation device provided by this invention allows the central tube assembly and outer tube assembly to undergo relative displacement after being pushed by the temperature memory alloy 600, the central tube assembly and outer tube assembly change from a fixed connection state to a free state that can slide relative to each other along the axis of the central tube assembly. This allows the length of the sleeve expansion compensation device to change freely within a certain range. Specifically, when the temperature rises, the sleeve length increases, reducing the distance between the connecting ends of the upper and lower sleeves, thus compressing the sleeve expansion compensation device; when the temperature decreases, the sleeve length decreases, increasing the distance between the connecting ends of the upper and lower sleeves, thus stretching the sleeve expansion compensation device. Therefore, by compensating for the change in sleeve length through the relative sliding of the central tube assembly and outer tube assembly, the internal stress of the sleeve caused by the temperature-induced length change is reduced, keeping the internal stress value of the sleeve within the yield limit range and reducing sleeve damage. This avoids the situation where, when the length of a single sleeve changes due to temperature changes, the length change is hindered by the fixed ends, leading to an increase in internal stress in the sleeve.

[0037] The structure and shape of the sleeve expansion compensation device provided in this embodiment will be described in detail below with reference to the accompanying drawings:

[0038] The central tube assembly in this embodiment includes a central tube 500, such as... Figure 1 As shown, a limiting boss 510 is provided in the middle of the outer circle of the central tube 500, and external threads are provided on both sides of the central tube 500.

[0039] Furthermore, a sealing groove is provided on the outer side of the limiting boss 510, and a sealing ring is provided at the sealing groove to improve the sealing performance between the limiting boss 510 and the outer tube assembly.

[0040] Furthermore, the outer surface of the center tube 500 is coated to improve the thermochemical stability and corrosion resistance of the outer surface of the center tube 500, thereby increasing the service life of the tool.

[0041] Furthermore, the outer surface of the central tube 500 is chrome-plated to improve the stability, wear resistance, and smoothness of the outer surface of the central tube 500.

[0042] Furthermore, the central pipe assembly also includes a lower connector 1300, such as... Figure 1 , 5 As shown, the lower connector 1300 is fitted onto the lower side of the central tube 500, and the upper connector 100 has an internal thread on its upper side, which engages with the external thread on the lower side of the central tube 500 to screw the central tube 500 to the upper connector 100.

[0043] Furthermore, a third stepped surface 1320 is provided on the inner side of the lower connector 1300. The third stepped surface 1320 cooperates with the lower end surface of the central tube 500 to limit the depth of the lower connector 1300 inserted into the central tube 500.

[0044] Further, the lower end of the lower joint 1300 is provided with external threads for connecting with the casing.

[0045] Further, the upper side of the third step surface 1320 is provided with a second sealing groove 1310, and a sealing ring is arranged in the second sealing groove 1310 to improve the sealing performance of the connection between the lower joint 1300 and the central pipe 500.

[0046] The outer pipe group in the embodiment includes a compression ring 400, as shown in Figure 1 、 2 The compression ring 400 includes a main body part 410 abutting against the top end surface of the central pipe 500 and an extension part 420 extending into the accommodation space, and the extension part 420 is sleeved on the central pipe 500 and is in sliding connection with the central pipe 500.

[0047] Further, the outer pipe group further includes an outer pipe 200, as shown in Figure 1 The outer pipe 200 is sleeved on the central pipe 500, and the inner circle of the outer pipe 200, the outer circle of the central pipe 500, the limiting boss 510 and the lower end surface of the extension part 420 form an accommodation space, and the accommodation space is filled with the temperature memory alloy 600.

[0048] Further, the outer pipe group further includes an upper joint 100, the lower side of the upper joint 100 is provided with external threads, the upper side of the outer pipe 200 is provided with internal threads, and the upper joint 100 is inserted into the outer pipe 200 and is in fixed connection with the outer pipe 200 through threads. The upper side of the upper joint 100 is provided with internal threads for connecting with the casing.

[0049] Further, the outer circle of the lower side of the upper joint 100 is provided with a sealing groove, the sealing groove is arranged below the external threads of the lower side of the upper joint 100, and a sealing ring is arranged in the sealing groove to improve the sealing performance between the upper joint 100 and the outer pipe 200.

[0050] Further, the outer circle of the upper joint 100 is provided with a step surface, the step surface abuts against the top end surface of the central pipe 500, and the step surface is used to limit the depth of the insertion of the upper joint 100 into the outer pipe 200.

[0051] Further, a buffer washer ring 300 is arranged between the upper joint 100 and the compression ring 400, the lower end surface of the upper joint 100 is in contact with the upper end surface of the buffer washer ring 300, and the upper end surface of the main body part 410 of the compression ring 400 is in contact with the lower end surface of the buffer washer ring 300, which is used to reduce the impact of the compression ring 400 on the upper joint 100 when the temperature memory alloy 600 is heated and expanded, and to limit the distance of the upward movement of the compression ring 900 through the upper joint 100.

[0052] Further, the outer pipe group further includes a variable buckle joint 700, as shown in Figure 1 、 3As shown, the variable screw joint 700 comprises an upper joint 710 and a lower joint 720; the upper joint 710 is sleeved on the lower side of the outer tube 200, the upper joint 710 is provided with an internal thread, the lower side of the outer tube 200 is provided with an external thread, and the upper joint 710 is connected with the lower side of the outer tube 200 through the thread; meanwhile, the end of the lower side thread of the outer tube 200 is provided with a stepped surface, the stepped surface abuts against the upper end surface of the upper joint 710, so as to limit the depth of the upper joint 710 sleeved into the outer tube 200; the inner circle at the connection of the upper joint 710 and the lower joint 720 of the outer tube 200 is provided with a first boss 740, the first boss 740 abuts against the lower end surface of the outer tube 200, so as to limit the depth of the upper joint 710 sleeved into the outer tube 200.

[0053] Further, the outer tube assembly further comprises a limiting ring 800, the upper end surface of the limiting ring 800 is in contact with the lower end surface of the first boss 740, and the space between the limiting ring 800 and the limiting boss 510 constitutes a sliding space of the central tube assembly and the outer tube assembly, and the distance of the downward movement of the central tube assembly is limited through the cooperation of the limiting ring 800 and the limiting boss 510.

[0054] Further, the outer tube assembly further comprises a pressing cap ring 900, as shown in Figure 1 、 4 As shown, the upper side of the pressing cap ring 900 is provided with an internal thread, the lower joint 720 is provided with an external thread, the pressing cap ring 900 is sleeved on the lower joint 720 and is connected with the lower joint 720 through the thread. The pressing cap ring 900 is provided with a second stepped surface 910, the second stepped surface 910 is in contact with the lower end surface of the limiting ring 800, and cooperates with the lower end surface of the first boss 740 to jointly limit the position of the limiting ring 800. Further, the variable screw joint 700 is further provided with a first stepped surface 730, the first stepped surface 730 is located at the end of the external thread of the lower joint 720, and limits the depth of the pressing cap ring 900 sleeved into the lower joint 720.

[0055] Further, the outer tube assembly further comprises a pin 1100, the pin 1100 is inserted into the central tube 500 after penetrating the pressing cap ring 900 in the radial direction, so that the central tube 500 is fixedly connected with the pressing cap ring 900, and then the central tube assembly and the outer tube assembly are fixedly connected.

[0056] Further, the inner side of the pressing cap ring 900 is further provided with a first sealing groove 920, a composite sealing ring 1000 is arranged in the first sealing groove 920, the composite sealing ring 1000 forms a sliding sealing cooperation with the outer surface of the central tube 500, so as to ensure the sealing performance of the tool in the process of well cementation or later operation.

[0057] Further, the outer tube group further comprises a high-temperature-resistant sand prevention ring 1200, which is arranged above the lower joint 1300 and connected with the lower end of the pressure cap ring 900, so as to prevent the downhole debris from entering the outer surface of the central tube 500, thereby prolonging the service life of the tool.

[0058] Further, the casing telescopic compensation device provided by the present application can be provided with a plurality of devices according to the length of the casing string, so as to ensure that the stress of the casing is fully eliminated.

[0059] The assembling process of the casing telescopic compensation device provided by the present application is as follows:

[0060] First, the outer tube 200, the variable buckle joint 700, the limiting ring 800, the pressure cap ring 900 and the high-temperature-resistant sand prevention ring 1200 are sequentially connected; then the composite sealing ring 1000 is loaded on the pressure cap ring 900; then the sealing ring is sleeved on the limiting boss 510 of the central tube 500, and the sealing ring is sleeved at the second sealing groove 1310 of the lower joint 1300; then the central tube 500 is inserted into the outer tube 200, and the lower joint 1300 is sleeved on the central tube 500 and connected through threads; then the pin 1100 is punched to fixedly connect the pressure cap ring 900 and the central tube 500; then the temperature memory alloy 600 is loaded into the accommodating space and inserted into the pressure ring 400; then the buffer pad ring 300 is placed; finally, the sealing ring is sleeved on the upper joint 100, and the upper joint 100 is inserted into the outer tube 200 and connected through threads.

[0061] The working process of the casing telescopic compensation device provided by the present application is as follows:

[0062] The casing is divided into two sections and connected to the casing telescopic compensation device at both ends. When installing the casing, the lower end of the casing is lowered into the well, and then the position of the lower end of the casing is fixed. After the temperature in the well rises, the temperature memory alloy 600 expands, first pushing the compression ring 400, making the compression ring 400 extrude the buffer ring 300, and finally extruding the upper joint 100, thereby causing the central pipe group and the outer pipe group to move relatively. Since the lower end of the casing is fixed and the central pipe group is connected to the casing below the casing telescopic compensation device, the central pipe group is relatively stationary, and the outer pipe group is pushed upward, thereby shearing the pin 1100, so that the outer pipe group and the central pipe group can slide along the axial direction. Then, according to the sliding distance of the central pipe group and the outer pipe group, the position of the casing above the casing telescopic compensation device is adjusted, so that the length of the casing telescopic compensation device can be elongated or shortened in the axial direction to ensure sufficient telescopic compensation and fix the casing above the casing telescopic compensation device. When the temperature continues to rise, the length of the casing at both ends of the casing telescopic compensation device is elongated, and the length of the casing telescopic compensation device is compressed; when the temperature drops, the length of the casing at both ends of the casing telescopic compensation device is shortened, and the length of the casing telescopic compensation device is elongated. The change in the length of the casing telescopic compensation device offsets the stress generated by the temperature change of the casing, controls the stress value in the casing, and reduces the damage caused by stress in the casing.

[0063] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A telescoping casing compensation device, characterized by, The center tube group and the outer tube group form a containing space between them, and a temperature memory alloy (600) is arranged in the containing space, the temperature memory alloy (600) is configured to be able to push the center tube group and the outer tube group to relatively displace, so that the center tube group and the outer tube group are changed from a fixed connection state to a free state capable of relatively sliding along the axis direction of the center tube group. The center tube group includes a center tube (500), and a limiting boss (510) is arranged at the middle part of the outer circle of the center tube (500), and the outer side of the limiting boss (510) is in contact with the inner side of the outer tube group. The outer tube group further includes a variable buckle joint (700), the variable buckle joint (700) includes an upper joint (710) and a lower joint (720), and a first boss (740) is arranged on the inner circle at the connection position of the upper joint (710) and the lower joint (720); the upper joint (710) is sleeved on the lower end of the outer tube (200) and is screwed with the outer tube (200), and the first boss (740) is in contact with the lower end of the outer tube (200). The outer tube group further includes a limiting ring (800), the limiting ring (800) is arranged below the first boss (740), and the space between the limiting ring (800) and the limiting boss (510) is a sliding space of the center tube group and the outer tube group. The outer tube group further includes a variable buckle joint (700), the variable buckle joint (700) includes an upper joint (710) and a lower joint (720), and a first boss (740) is arranged on the inner circle at the connection position of the upper joint (710) and the lower joint (720); the upper joint (710) is sleeved on the lower end of the outer tube (200) and is screwed with the outer tube (200), and the first boss (740) is in contact with the lower end of the outer tube (200).

2. A telescoping compensation device for a conduit as defined in claim 1, wherein, The outer tube group further includes a limiting ring (800), the limiting ring (800) is arranged below the first boss (740), and the space between the limiting ring (800) and the limiting boss (510) is a sliding space of the center tube group and the outer tube group.

3. A telescoping compensation device for a conduit as defined in claim 2, wherein, The outer tube group further includes a variable buckle joint (700), the variable buckle joint (700) includes an upper joint (710) and a lower joint (720), and a first boss (740) is arranged on the inner circle at the connection position of the upper joint (710) and the lower joint (720); the upper joint (710) is sleeved on the lower end of the outer tube (200) and is screwed with the outer tube (200), and the first boss (740) is in contact with the lower end of the outer tube (200).

4. A telescoping compensation device for a conduit as defined in claim 3, wherein, The outer tube group further includes a limiting ring (800), the limiting ring (800) is arranged below the first boss (740), and the space between the limiting ring (800) and the limiting boss (510) is a sliding space of the center tube group and the outer tube group.

5. A telescoping compensation device for a conduit as defined in claim 4, wherein, The outer tube group further includes a variable buckle joint (700), the variable buckle joint (700) includes an upper joint (710) and a lower joint (720), and a first boss (740) is arranged on the inner circle at the connection position of the upper joint (710) and the lower joint (720); the upper joint (710) is sleeved on the lower end of the outer tube (200) and is screwed with the outer tube (200), and the first boss (740) is in contact with the lower end of the outer tube (200).

6. A telescoping compensation device for a conduit as defined in claim 5, wherein The outer tube group further includes a limiting ring (800), the limiting ring (800) is arranged below the first boss (740), and the space between the limiting ring (800) and the limiting boss (510) is a sliding space of the center tube group and the outer tube group.

7. A telescoping compensation device for a conduit as defined in claim 6, wherein, The outer tube group further comprises a high-temperature-resistant sand control ring (1200), an upper end of the high-temperature-resistant sand control ring (1200) being connected with a lower end of the pressure cap ring (900).

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