Blanking plug and production tubular column

Abstract

The utility model relates to a blanking plug and a production pipe column, the blanking plug comprises a pipe body assembly, the pipe body assembly is arranged in an oil well, an annular cavity is formed between the pipe body assembly and the oil well, the pipe body assembly comprises a pipe cavity, and the pipe body assembly is provided with an air inlet communicated with the pipe cavity; and the sealing piston is arranged in the pipe cavity, the sealing piston is used for blocking the air inlet hole, the sealing piston divides the pipe cavity into a first sub-cavity and a second sub-cavity, the first sub-cavity and the second sub-cavity are arranged in a spaced mode in the direction away from the coiled tubing, a pressure balance cavity is formed between the sealing piston and the pipe body assembly, and the pressure balance cavity communicates with the annular cavity. According to the blanking plug, in the process that the continuous oil pipe is lowered into an oil well, the continuous oil pipe can be effectively plugged through the sealing piston, the beating-off pressure of the sealing piston is controllable, the operation risk is reduced, and the reliability of drainage and gas production of the continuous oil pipe is improved.

Description

Technical Field

[0001] This application relates to the field of coiled tubing tooling technology, and in particular to a plug and production tubing string. Background Technology

[0002] In the process of natural gas extraction in the oil and gas industry, as production time increases and bottom-hole energy decreases, the flow rate in a natural gas production well becomes insufficient to carry the fluid out of the wellbore. Over time, the fluid level in the well will rise higher and higher until it exceeds the pressure of the natural gas at the bottom of the well, causing flooding and rendering the natural gas well unusable. To solve the problem of draining fluid from natural gas wells, a certain length of coiled tubing is usually suspended at the wellhead. This can reduce the critical fluid-carrying velocity to a certain extent, thereby increasing the fluid-carrying capacity of the gas well and carrying the fluid out of the wellbore, ensuring normal production of the gas well.

[0003] In related technologies, to prevent gas from entering the coiled tubing during the running-in process, a plug is typically connected to the end of the velocity tubing. After the velocity tubing is installed, the plug is removed by pressurizing the coiled tubing, establishing a production path. Removing the plug generally requires overcoming the combined shear pressure of the pin and the well pressure. Due to the high bottom-hole pressure, sometimes the plug cannot be removed, preventing the establishment of a production path. Adopting other measures later would introduce significant well control risks and incur substantial operating costs. Utility Model Content

[0004] This application provides a plug and production string to solve the technical problem that existing plugs need to overcome the sum of pin shear pressure and well pressure. Due to the high bottom hole pressure, the plug head of the plug may not be able to be properly removed, resulting in the inability to establish a production channel.

[0005] This application provides a plug, installed at the end of a continuous tubing, the plug comprising:

[0006] A pipe assembly is disposed in an oil well and forms an annular cavity with the oil well. The pipe assembly includes a pipe cavity and is provided with an air inlet communicating with the pipe cavity.

[0007] A sealing piston is disposed within the cavity. The sealing piston is used to block the air inlet and divides the cavity into a first sub-cavity and a second sub-cavity. The first sub-cavity and the second sub-cavity are spaced apart along a direction away from the continuous tubing. The sealing piston is provided with a pressure balance chamber, which communicates with the annular cavity.

[0008] In one possible implementation, the tubing assembly includes a connecting pipe and a vent pipe connected together, wherein the end of the connecting pipe away from the vent pipe forms an assembly joint for connection with the continuous tubing, the sealing piston is connected to the vent pipe, and the air inlet is provided on the vent pipe.

[0009] In one possible implementation, the vent pipe is provided with a pressure balancing hole, which is connected to the pressure balancing chamber.

[0010] In one possible implementation, the tube assembly is provided with shear pins, and the sealing piston is connected to the inner wall of the vent tube via the shear pins.

[0011] In one possible implementation, the sealing piston is provided with a first step, and the pressure balance chamber is formed between the first step and the inner wall surface of the vent pipe; the first step has a first pressure-bearing area, and the end of the sealing piston away from the continuous oil pipe has a second pressure-bearing area, the first pressure-bearing area and the second pressure-bearing area being equal.

[0012] In one possible implementation, a guide head is also included, which is disposed at the end of the tubing assembly away from the coiled tubing.

[0013] In one possible implementation, the sealing piston is provided with a second step, and the guide head is provided with a third step at one end near the continuous tubing, the third step being used to limit the second step.

[0014] In one possible implementation, a sealed cavity is formed between the second step, the third step, and the inner wall of the vent pipe, and a compressible gas is introduced into the sealed cavity.

[0015] In one possible implementation, the vent tube is provided with a first set screw, and the guide head is connected to the inner wall surface of the vent tube via the first set screw.

[0016] In one possible implementation, the vent pipe is provided with a second set screw, and the connecting pipe is connected to the inner wall of the vent pipe via the second set screw.

[0017] Secondly, this application provides a production string including a coiled tubing and a plug as described above.

[0018] The technical solutions provided in this application have the following advantages compared with the prior art:

[0019] The plug and production tubing provided in this embodiment allow gas from the well to enter the pressure balance chamber from the annulus cavity and then enter the second sub-cavity, ensuring that the pressure of the gas in the pressure balance chamber on the sealing piston is equal to the pressure of the gas in the second sub-cavity on the sealing piston. This allows the sealing piston to be in a pressure balance state, eliminating the need to overcome the well pressure during the process of removing the sealing piston. When the coiled tubing is lowered to the set position in the well, it is pressurized until the pressure in the first sub-cavity reaches a preset pressure value. Under this pressure, the sealing piston switches from the plugging position to a free sliding state and slides towards the end of the tubing away from the coiled tubing, thus connecting the annulus cavity, the air inlet, the first sub-cavity, and the coiled tubing, thereby establishing a gas production channel. During the pressurization process, the preset pressure value is unaffected by the bottom hole pressure, meaning the pressure required to remove the sealing piston is not affected by the bottom hole pressure, ensuring reliable removal of the sealing piston and reducing operational risks.

[0020] Since the production tubing includes the plug as described above, and the pressure balancing chamber is connected to the annular cavity, it naturally possesses the technical effects of the plug embodiment described above. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0024] Figure 1 A schematic diagram of the structure of a blocker provided in this application embodiment. Figure 1 ;

[0025] Figure 2 for Figure 1 The diagram shown illustrates the working principle of the plug, where the sealing piston is in the plugging position, and the arrow indicates the pressure direction of the oil well gas on the sealing piston.

[0026] Figure 3 Schematic diagram of the blocker provided in the embodiments of this application Figure 2 .

[0027] Explanation of reference numerals in the attached figures:

[0028] Z-axis direction;

[0029] 100. Blocker;

[0030] 1. Tube assembly; 11. Tube cavity; 111. First sub-cavity; 112. Second sub-cavity; 12. Connecting pipe; 121. Assembly joint; 13. Vent pipe; 131. Air inlet; 132. Pressure balance hole; 133. First set screw; 134. Second set screw;

[0031] 2. Sealed piston; 21. Pressure balance chamber; 22. First step; 23. Second step; 24. Sealed cavity;

[0032] 3. Shear pin; 4. Guide head; 41. Third step; 5. First sealing ring; 6. Second sealing ring; 7. Third sealing ring; 8. Fourth sealing ring; 9. Fifth sealing ring;

[0033] 200. Coiled tubing;

[0034] 300, oil well; 310, annular cavity. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0037] For ease of description, spatial relative terms may be used in the text to describe the relative position or movement of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "front," "back," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure undergoes a positional flip, orientation change, or change of motion, these directional indications will change accordingly. For instance, an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0038] In related technologies, to prevent gas from entering the coiled tubing, a plug is typically connected to the end of the velocity tubing. After the velocity tubing is installed, the plug is removed by pressurizing the coiled tubing, establishing a production path. Removing the plug generally requires overcoming the sum of the pin shear pressure and the well pressure. Due to the high bottomhole pressure, sometimes the plug cannot be removed. If the plug cannot be removed, a production path cannot be established. Adopting other measures later would introduce significant well control risks and incur substantial operating costs.

[0039] To address the problem that existing plugging devices need to overcome the sum of pin shearing pressure and well pressure, and that the uncontrollable bottom hole pressure leads to uncontrollable plug removal pressure, potentially preventing the plug from being properly removed and thus hindering the establishment of a production channel, this application provides a method that can effectively plug coiled tubing using a sealing piston, with controllable piston removal pressure, reducing operational risks and improving the reliability of coiled tubing drainage and gas production.

[0040] like Figure 1 and Figure 2As shown, this application embodiment provides a plug 100, installed at the end of a coiled tubing 200. The plug 100 includes a tubing assembly 1 and a sealing piston 2. The tubing assembly 1 is disposed in an oil well 300, forming an annular cavity 310 between the tubing assembly 1 and the oil well 300. The tubing assembly 1 includes a cavity 11 and is provided with an air inlet 131 communicating with the cavity 11. The sealing piston 2 is disposed in the cavity 11 and is used to block the air inlet 131. The sealing piston 2 divides the cavity 11 into a first sub-cavity 111 and a second sub-cavity 112. The first sub-cavity 111 and the second sub-cavity 112 are spaced apart along a direction away from the coiled tubing 200. The sealing piston 2 is provided with a pressure balancing chamber 21, which is located between the first sub-cavity 111 and the second sub-cavity 112 and communicates with the annular cavity 310. The sealing piston 2 has a blocking position fixedly connected to the tube assembly 1, and a sliding state that can slide within the tube cavity 11. When the pressure of the first sub-cavity 111 reaches a preset pressure value, the sealing piston 2 switches from the blocking position to the sliding state and slides towards the end of the tube cavity 11 away from the continuous oil pipe 200, so that the annular cavity 310, the air inlet 131, the first sub-cavity 111 and the continuous oil pipe 200 are connected.

[0041] By installing the plug 100 at the end of the coiled tubing 200, the coiled tubing 200 can be inserted into the well 300 in an internally depressurized state. A sealing piston 2 is installed in the lumen 11 of the tubing assembly 1, which divides the lumen 11 into a first sub-cavity 111 and a second sub-cavity 112. Thus, during the well running process of the coiled tubing 200 with the plug 100 installed, gas in the well enters the coiled tubing 200, and gas in the well 300 can enter the second sub-cavity 112 from the annular cavity 310. When the sealing piston 2 is in the plugging position, it can block the air inlet 131 and block the gas in the second sub-cavity 112, preventing gas from entering the first sub-cavity 111 and being ejected from the wellhead through the coiled tubing 200, thus ensuring the personal safety of the operators at the wellhead. Since the pressure balancing chamber 21 is connected to the annular cavity 310, the gas in the well 300 can enter the pressure balancing chamber 21 from the annular cavity 310. The gas in the well 300 then enters the second sub-cavity 112 from the annular cavity 310, making the pressure of the gas in the pressure balancing chamber 21 on the sealing piston 2 equal to the pressure of the gas in the second sub-cavity 112 on the sealing piston 2. This allows the sealing piston 2 to be in a pressure balance state, and the process of removing the sealing piston 2 does not require overcoming the well pressure. When the coiled tubing 200 is lowered into the set position of the well 300, the coiled tubing 200 is pressurized, causing the pressure in the first sub-cavity 111 to reach the preset pressure value. Under the action of pressure, the sealing piston 2 switches from the blocking position to a free sliding state and slides towards the end of the tubing 11 away from the coiled tubing 200, thereby connecting the annular cavity 310, the air inlet 131, the first sub-cavity 111, and the coiled tubing 200, thus establishing a gas production channel. During the pressurization process, the preset pressure value is not affected by the bottom hole pressure, that is, the pressure at which the sealing piston 2 is removed is not affected by the bottom hole pressure, thereby ensuring that the sealing piston 2 is reliably removed and reducing the operational risk.

[0042] The plug 100 provided in this application embodiment can effectively block the coiled tubing 200 during the process of lowering the coiled tubing 200 into the well 300 through the sealing piston 2. Moreover, the pressure of the sealing piston 2 being released is controllable, which reduces the operational risk and improves the reliability of drainage and gas production from the coiled tubing 200.

[0043] In some embodiments, such as Figure 1As shown, the pipe assembly 1 includes a connecting pipe 12 and a vent pipe 13 connected together. The end of the connecting pipe 12 away from the vent pipe 13 forms an assembly joint 121 for connection with the coiled tubing 200. A sealing piston 2 is connected to the vent pipe 13, and an air inlet 131 is provided on the vent pipe 13. This arrangement facilitates the connection of the pipe assembly 1 to the coiled tubing 200 via the assembly end, improving the reliability of the connection between the pipe assembly 1 and the coiled tubing 200. The sealing piston 2 is connected to the vent pipe 13, and the air inlet 131 is provided on the vent pipe 13. The sealing piston 2 is connected to the inner wall of the vent pipe 13 and blocks the air inlet 131, ensuring that the sealing piston 2 can effectively block the gas in the second sub-cavity 112 and the gas in the air inlet 131, preventing the gas in the second sub-cavity 112 and the air inlet 131 from entering the first sub-cavity 111.

[0044] It should be noted that the assembly joint 121 can be connected to the continuous tubing 200 using a grooved structure, a recessed structure, a rivet structure, a slip type, or other connection structures.

[0045] In some embodiments, such as Figure 2 As shown, the vent pipe 13 is provided with a pressure balance hole 132, which is connected to the pressure balance chamber 21. By providing the pressure balance hole 132, the pressure balance chamber 21 is connected to the annular cavity 310, allowing gas in the oil well 300 to enter the pressure balance chamber 21 from the annular cavity 310. This makes the pressure of the gas in the pressure balance chamber 21 on the sealing piston 2 equal to the pressure of the gas in the second sub-cavity 112 on the sealing piston 2, thereby keeping the sealing piston 2 in a pressure balance state. The pressure at which the sealing piston 2 is knocked off is controllable, reducing operational risks.

[0046] In some embodiments, such as Figure 1 As shown, the pipe assembly 1 is equipped with shear pins 3, and the sealing piston 2 is connected to the inner wall of the vent pipe 13 through the shear pins 3. The preset pressure value can be set to the shearing pressure of the shear pins, that is, the shearing pressure of the shear pins of the sealing piston 2 is not affected by the bottom hole pressure, thereby ensuring that the sealing piston 2 is reliably knocked off and reducing the operational risk.

[0047] When the coiled tubing 200 is lowered to the designated position in the well 300, it is pressurized until the pressure within the first sub-cavity 111 reaches the preset pressure value. This causes the shear pin to shear off, and the sealing piston 2, under pressure, switches from a blocked position to a free-sliding state, sliding towards the end of the tubing 11 away from the coiled tubing 200. This connects the annular cavity 310, the air inlet 131, the first sub-cavity 111, and the coiled tubing 200, thus establishing a gas production channel. During the pressurization process, the preset pressure value is unaffected by the bottom hole pressure, ensuring the reliable removal of the sealing piston 2 and reducing operational risks.

[0048] Among them, such as Figure 2 As shown, the sealing piston 2 is provided with a first step 22, and a pressure balance chamber 21 is formed between the first step 22 and the inner wall surface of the vent pipe 13. Gas in the oil well 300 enters the pressure balance chamber 21 through the pressure balance hole 132, and then acts on the first step 22, so that the first step 22 has a first pressure-bearing area S1; gas in the oil well 300 enters the pipe 11 through the second sub-cavity 112, and then acts on the end of the sealing piston 2 away from the coiled tubing 200, so that the end of the sealing piston 2 away from the coiled tubing 200 has a second pressure-bearing area S2, S1 = S2, so that the bottom hole pressure on the end of the sealing piston 2 away from the coiled tubing 200 is equal to the bottom hole pressure on the first step 22. That is to say, the pressure of the gas in the pressure balance chamber 21 on the sealing piston 2 is F1, and the pressure of the gas in the second sub-cavity 112 on the sealing piston 2 is F2, F1 = F2, and the sealing piston 2 is in a pressure balance state.

[0049] In some embodiments, such as Figure 1 As shown, it also includes a guide head 4, which is located at the end of the tubing assembly 1 furthest from the coiled tubing 200. In this way, during the process of lowering the coiled tubing 200 to the well 300, the guide head 4 guides the coiled tubing 200, thereby improving the gas production efficiency of the coiled tubing 200.

[0050] If the existing plug is completely knocked down to the bottom of the well, the plug 100 may affect subsequent operations, causing drainage and gas production operations to be unable to proceed normally, which is time-consuming and labor-intensive, reduces the production efficiency of natural gas, prolongs the production time of natural gas, and is detrimental to the economics of drainage and gas production. Therefore, the guide head 4 of this embodiment is provided with a third step 41 to limit the sealing piston 2.

[0051] Furthermore, such as Figure 1 and Figure 2 As shown, the sealing piston 2 is provided with a second step 23, and the guide head 4 is provided with a third step 41 at the end near the coiled tubing 200. When the sealing piston 2 switches from the blocking position to the sliding state and slides towards the end of the cavity 11 away from the coiled tubing 200, the second step 23 abuts against the third step. When the coiled tubing 200 is lowered into the set position of the well 300, the coiled tubing 200 is pressurized so that the pressure in the first sub-cavity 111 reaches the preset pressure value, the shear pin is sheared, and the sealing piston 2 switches from the blocking position to the free sliding state under the pressure and slides towards the end of the cavity 11 away from the coiled tubing 200 until the second step 23 abuts against the third step 41. The third step 41 acts as a limit for the sealing piston 2, preventing the sealing piston 2 from falling out of the cavity 11 and into the well 300, thereby ensuring the normal operation of drainage and gas production.

[0052] In this embodiment, the sealing piston 2 can effectively block the continuous tubing 200, the pressure of the plug 100 can be controlled, and the plug 100 will not fall off as a whole, thereby improving the reliability of drainage and gas extraction of the continuous tubing 200, making the operation convenient and quick, improving the gas production efficiency, shortening the gas production time, and improving the economy of drainage and gas extraction.

[0053] like Figure 1 As shown, a sealed cavity 24 is formed between the inner wall surfaces of the second step 23, the third step, and the vent pipe 13. The sealed cavity 24 can be vented with compressible gases such as air and nitrogen. When the coiled tubing 200 is lowered to the set position in the well 300, it is pressurized until the pressure inside the first sub-cavity 111 reaches a preset pressure value. The shear pin is then sheared, and the sealing piston 2, under pressure, switches from a blocked position to a free-sliding state and slides towards the end of the cavity 11 away from the coiled tubing 200, thereby compressing the sealed cavity 24. Before pressurizing the coiled tubing 200, the sealing piston 2 is in a pressure equilibrium state. At this time, the sealed cavity 24 has an initial length along the axial direction of the cavity 11, which can be the Z-direction shown in the figure. The initial length is designed according to the gas compression characteristics to ensure sufficient downward space when the sealing piston 2 is removed. The air inlet 131 is connected to the first sub-cavity 111, allowing the production channel to be fully opened.

[0054] It should be noted that the pressure of the compressible gas inside the sealed cavity 24 is much lower than the gas pressure of the oil well 300. Therefore, during the pressurization process, the preset pressure value is not affected by the bottom hole pressure, thereby ensuring that the sealing piston 2 is reliably removed and reducing the operational risk.

[0055] In some embodiments, such as Figure 1 As shown, the vent pipe 13 and the guide head 4 are connected by threads. The vent pipe 13 is equipped with a first set screw 133, and the guide head 4 is connected to the inner wall of the vent pipe 13 through the first set screw 133. This configuration improves the connection stability between the guide head 4 and the vent pipe 13, ensuring that the guide head 4 will not fall off during normal operation of the plugger 100, thereby improving the working stability of the plugger 100.

[0056] In some embodiments, such as Figure 1 As shown, the vent pipe 13 and the connecting pipe 12 are connected by threads. The vent pipe 13 is provided with a second set screw 134, and the connecting pipe 12 is connected to the inner wall of the vent pipe 13 through the second set screw 134. This arrangement improves the connection stability between the connecting pipe 12 and the vent pipe 13, thereby improving the working stability of the plugger 100.

[0057] To ensure a tight seal, such as Figure 3As shown, the end of the connecting pipe 12 furthest from the continuous tubing 200 is provided with a first annular groove, in which a first sealing ring 5 is embedded, thus ensuring the sealing between the connecting pipe 12 and the vent pipe 13. The sealing piston 2 is provided with a second, third, and fourth annular groove, which are spaced apart sequentially along the direction away from the continuous tubing 200. The second annular groove is provided with a second sealing ring 6, the third annular groove with a third sealing ring 7, thus ensuring the sealing between the sealing piston 2 and the vent pipe 13, and the fourth annular groove with a fourth sealing ring 8, thus ensuring the sealing between the sealing piston 2 and the guide head 4. The guide head 4 is provided with a fifth annular groove, in which a fifth sealing ring 9 is embedded, thus ensuring the sealing between the guide head 4 and the vent pipe 13.

[0058] This application also provides a production string, including coiled tubing 200 and the plug 100 as described above. The production string can be lowered into or retrieved from the well 3001. Since the production string includes the plug 100 as described above, and the pressure balance chamber 21 is connected to the annular cavity 310, it naturally possesses the technical effects of the plug 100 embodiment described above. During pressurization, the pressure required to remove the plug 100 is not affected by the bottom hole pressure, thereby ensuring reliable removal of the sealing piston 2 and reducing operational risks.

[0059] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a specific order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0060] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0061] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A plug for installation on the end of a coiled tubing, characterised in that, The blocker includes: A pipe assembly is disposed in an oil well and forms an annular cavity with the oil well. The pipe assembly includes a pipe cavity and is provided with an air inlet communicating with the pipe cavity. A sealing piston is disposed within the cavity. The sealing piston is used to block the air inlet and divides the cavity into a first sub-cavity and a second sub-cavity. The first sub-cavity and the second sub-cavity are spaced apart along a direction away from the continuous tubing. The sealing piston is provided with a pressure balance chamber, which communicates with the annular cavity.

2. The obturator of claim 1, wherein, The pipe assembly includes a connecting pipe and a vent pipe connected together, wherein the end of the connecting pipe away from the vent pipe forms an assembly joint for connection with the continuous tubing, the sealing piston is connected to the vent pipe, and the air inlet is provided on the vent pipe.

3. The obturator of claim 2, wherein, The vent pipe is provided with a pressure balance hole, which is connected to the pressure balance chamber.

4. The obturator of claim 2, wherein, The tube assembly is provided with shear pins, and the sealing piston is connected to the inner wall of the vent pipe through the shear pins.

5. The obturator of claim 2, wherein, The sealing piston is provided with a first step, and the pressure balance chamber is formed between the first step and the inner wall surface of the vent pipe; the first step has a first pressure-bearing area, and the end of the sealing piston away from the continuous oil pipe has a second pressure-bearing area, the first pressure-bearing area and the second pressure-bearing area are equal.

6. The obturator of claim 2, wherein, It also includes a guide head disposed at one end of the tubing assembly away from the coiled tubing.

7. The obturator of claim 6, wherein, The sealing piston is provided with a second step, and the guide head is provided with a third step at one end near the continuous oil pipe. The third step is used to limit the second step.

8. The obturator of claim 7, wherein, A sealed cavity is formed between the second step, the third step, and the inner wall of the vent pipe, and a compressible gas is introduced into the sealed cavity.

9. The obturator of claim 6, wherein, The vent tube is provided with a first set screw, and the guide head is connected to the inner wall of the vent tube through the first set screw.

10. The obturator of claim 2, wherein, The vent pipe is provided with a second set screw, and the connecting pipe is connected to the inner wall of the vent pipe through the second set screw.

11. A production string characterized by, Includes coiled tubing and a plug as described in any one of claims 1 to 10.

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