Soluble temperature measuring bridge plug

Abstract

The utility model relates to a soluble temperature measuring bridge plug, and the soluble center cone, soluble sealing element, slip and lower joint can be realized in the well through the cooperation of the releasing rod, soluble center cone, soluble sealing element, slip and lower joint and setting tool, and the temperature measuring device is carried in the soluble center cone and lower joint, so that the temperature of the soluble center cone and lower joint can be measured at the same time and separately, and the temperature and time curves of the positions of the soluble center cone and lower joint can be obtained, the relationship between the temperature and dissolution of the soluble center cone and lower joint can be reflected, and the material of the soluble center cone and lower joint can be selected according to the relationship, so that the dissolution time of the soluble center cone and lower joint can be shorter and closer, and the well production can be ensured to be faster.

Description

Technical Field

[0001] This utility model relates to the field of bridge plug structure technology, and in particular to a soluble temperature-sensing bridge plug. Background Technology

[0002] Soluble bridge plugs, as well completion fracturing tools, can self-degrade after fracturing, achieving zero residue and full bore, thus saving drilling and grinding costs. Existing bridge plugs can measure downhole temperature and provide feedback on downhole operating conditions, and therefore have been widely used. For example, patent application US20250257629A1 discloses a data acquisition system and method for oil exploration engineering. It discloses that at least one data recorder is installed on a bridge plug made of soluble material. After the bridge plug dissolves in the fracturing fluid, the at least one data recorder is allowed to float to the mouth of the oil exploration channel under the buoyancy of the fracturing fluid. The system also discloses that the data recorder is retrieved, and then a host computer is connected to the data recorder to read the data stored in the data memory of the data recorder, and the host computer analyzes the read data. By using a data logger mounted on the bridge plug, temperature and pressure changes during the well plugging process are monitored in real time. When the bridge plug dissolves, fracturing fluid can be used to float the data logger to the channel opening, where it can be retrieved and the data analyzed to determine the temperature and pressure in fractured areas. This allows exploration workers to more intuitively observe oil seepage in each fractured area. However, this technical solution does not describe the specific location of the data logger on the bridge plug; it only states that fracturing fluid can float the data logger to the channel opening during bridge plug dissolution. This means the data logger cannot connect to the setting parts of the bridge plug (such as the soluble central cone, soluble metal sealing ring, soluble slips, and soluble lower connector).

[0003] Although existing bridge plugs have downhole temperature measurement structures, in actual field applications, due to the complex factors of the downhole environment, it is necessary to detect the temperature and salinity of the bridge plug used for setting after setting (detected through flowback fluid) to guide the selection of materials for the setting part of the bridge plug, thereby improving the dissolution rate. Even if temperature measuring tools are installed on the setting part of the bridge plug to detect the temperature of dissolution after setting, the temperature varies in different parts, making it difficult to guide the selection of materials for different parts and thus making it difficult to better control the dissolution efficiency. If temperature detection is set for each part, the number of temperature detection devices required is too large. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of existing bridge plugs with temperature measurement functions, which cannot provide material selection guidance for the soluble central cone and lower connector used for setting the bridge plug, thus affecting production efficiency, and to provide a soluble temperature-measuring bridge plug.

[0005] In a first aspect, this utility model provides a soluble temperature measuring bridge plug, comprising a release lever, a soluble central cone, a soluble seal, a slip, and a lower connector. The release lever passes sequentially through the central through-hole of the soluble central cone, the slip, and the lower connector and is connected to the lower connector via a radially arranged shearing member. The soluble central cone has an outer conical surface at one end near the lower connector, and the outer diameter of the outer conical surface at one end near the lower connector is smaller than the outer diameter at the other end. The soluble seal is sleeved on the outside of the outer conical surface. One end of the slip abuts against the soluble seal, and the other end abuts against the lower connector. Both the soluble seal and the slip are movable along the outer conical surface away from the lower connector. Both the soluble central cone and the lower connector carry a temperature sensor.

[0006] Preferably, the soluble central cone carries at least three thermometers, and all the thermometers on the soluble central cone are evenly arranged along the circumference of the soluble central cone; And / or, The lower connector carries at least three thermometers, and all the thermometers on the lower connector are evenly arranged along the circumference of the lower connector.

[0007] Preferably, both the soluble central cone and the lower connector are equipped with three thermometers, and the three thermometers on the soluble central cone and the lower connector are correspondingly arranged.

[0008] Preferably, the lower connector has a diameter-protecting tooth on its outer side, and a receiving groove is provided on the end face of the lower connector away from the soluble central cone. The thermometer is disposed in the receiving groove, and the opening of the receiving groove is sealed by a sealing head.

[0009] Preferably, the soluble central cone has a receiving groove on the outer side of the opposite end of the outer cone surface, the thermometer is disposed in the receiving groove, and the opening of the receiving groove is sealed by a sealing head.

[0010] Preferably, it further includes a connecting tube, the release lever passes through the central through hole of the connecting tube, one end of the soluble central cone near the lower connector is sleeved on the outside of the connecting tube, the inner side of the lower connector and the outer side of the connecting tube are provided with a limiting structure, the limiting structure can restrict the lower connector from moving away from the soluble central cone relative to the connecting tube, and the outer side of the connecting tube and the inner side of the soluble central cone are provided with matching anti-retraction teeth, the anti-retraction teeth can restrict the connecting tube from moving towards the lower connector relative to the soluble central cone.

[0011] Preferably, the longitudinal section of the anti-retraction tooth is triangular or trapezoidal, and the side of the longitudinal section of the anti-retraction tooth away from the lower connector is an inclined surface.

[0012] Preferably, the limiting structure is a limiting groove provided on the inner side of the lower connector and a limiting protrusion provided on the outer side of the connecting pipe.

[0013] Preferably, the housing of the thermometer is made of stainless steel.

[0014] Preferably, the shearing element is a shearing disc or a shearing pin; The soluble sealing element is a metal sealing ring or a rubber ring. When the soluble sealing element is a rubber ring, a pressure ring is provided on the side of the rubber ring away from the lower connector. The pressure ring is sleeved on the outer conical surface of the soluble central cone and abuts against the adjacent end face of the rubber ring.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention provides a soluble temperature-sensing bridge plug. Through a release lever, a soluble central cone, a soluble seal, slips, and a lower connector, along with a setting tool, the soluble central cone, soluble seal, slips, and lower connector can be set in the well. Since both the soluble central cone and the lower connector are equipped with thermometers, the temperature of the soluble central cone and the lower connector can be measured simultaneously and separately. This allows for the generation of temperature versus time curves at the locations of the soluble central cone and the lower connector, reflecting the relationship between temperature and dissolution at these locations. This relationship can then be used to select the materials for the soluble central cone and the lower connector, resulting in shorter and more similar dissolution times for the soluble central cone and the lower connector, thus ensuring faster well production. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a soluble thermometric bridge plug; Figure 2 for Figure 1 A magnified view of a portion of circle A in the middle; Figure 3 A schematic diagram showing the assembly of the soluble temperature measuring bridge plug with the pusher and adapter in the setting tool; Figure 4 for Figure 3 A schematic diagram of the casing entering the well; Figure 5 This is a schematic diagram of setting a soluble thermometric bridge plug using a setting tool (some setting tools are not shown; these are existing setting methods). Figure 6 A schematic diagram illustrating the sealing of the central through-hole of a soluble central cone using a fracturing ball.

[0017] The markings in the diagram are: 1. Standard screw; 2. Push cylinder; 3. Release lever; 4. Soluble central cone; 41. Outer cone surface; 5. Sealing head; 6. Thermometer; 7. Pressure ring; 8. Rubber ring; 9. Slip seat; 10. Slip tooth; 11. Lower connector; 111. Limiting groove; 12. Connecting pipe; 121. Limiting protrusion; 122. Anti-retraction tooth; 13. Shear disc; 14. Diameter-maintaining tooth; 15. Adapter connector; 16. Sleeve; 17. Fracturing ball. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments. However, it should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0019] Unless otherwise specified, the terms "upper," "lower," "left," "right," "center," "inner," and "outer" used in the description of specific embodiments of this utility model to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product / equipment / device is usually placed during use. These terms are merely for the purpose of facilitating the description of the utility model solution or simplifying the description in specific embodiments, and for enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on this utility model.

[0020] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0021] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0022] Furthermore, in the description of the embodiments of this utility model, "several", "multiple", and "several" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0023] Furthermore, in the description of the technical solution of this utility model, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0024] Example 1 This embodiment provides a soluble temperature sensing bridge plug, such as Figure 1 As shown, it includes a release lever 3, a soluble central cone 4, a soluble seal, a slip, and a lower connector 11.

[0025] The release lever 3 passes sequentially through the central through hole of the soluble central cone 4, the slip, and the lower connector 11, and is connected to the lower connector 11 via a radially arranged shearing member. In an optional embodiment, the shearing member is a shearing disc 13 or a shearing pin, which is radially arranged and can be used for axial shearing. The soluble central cone 4 has an outer conical surface 41 at one end near the lower connector 11. The outer diameter of the outer conical surface 41 at one end near the lower connector 11 is smaller than the outer diameter at the other end. The soluble sealing member is sleeved on the outside of the outer conical surface 41. One end of the slip abuts against the soluble sealing member, and the other end abuts against the lower connector 11. Both the soluble sealing member and the slip can move along the outer conical surface 41 toward the end away from the lower connector 11.

[0026] In an optional embodiment, the soluble sealing element is a metal sealing ring or a rubber ring 8. Both the metal sealing ring and the rubber ring 8 can expand radially after axial compression, contacting the inner wall of the downhole casing to achieve a seal. When the soluble sealing element is a rubber ring 8, a pressure ring 7 is provided on the side of the rubber ring 8 away from the lower connector 11. The pressure ring 7 is sleeved on the outer conical surface 41 of the soluble central cone 4. The pressure ring 7 abuts against the adjacent end face of the rubber ring 8, and the pressure ring can axially compress the rubber ring 8, allowing the rubber ring 8 to deform radially better.

[0027] Before lowering the plug into the well, connect the release lever 3 of the soluble temperature measuring bridge plug to the adapter 15 of the setting tool, and then use the pusher 2 of the setting tool to abut one end of the soluble central cone 4. Figure 3 As shown; and the push cylinder 2 is prevented from retracting by the national standard screw 1; Downhole procedure: The setting tool and the soluble thermoelectric bridge plug are lowered together into the casing 16 using a tool string until the soluble thermoelectric bridge plug reaches the designated setting point. Figure 4 As shown; Setting process: The setting tool pushes the pusher 2 into the well, which in turn pushes the soluble central cone 4 into the well. Under the action of the tool string, adapter 15, and release rod 3, the axial shear force on the shearing component is less than the shear force it can withstand. Because of the presence of the shearing component, the release rod 3 is always connected to the lower connector 11, which can transmit the axial force along the bridge plug axis, so that the lower connector 11 will not move into the well. Under the compression of the lower connector 11 and the soluble central cone 4, the soluble seal and the slip can climb up the outer cone surface 41, and the soluble seal undergoes radial expansion deformation due to axial compression until it fits against the inner wall of the casing 16 to form a seal. The slip consists of a slip seat 9 and slip teeth 10 on the side wall of the slip seat 9. The expansion of the slip seat 9 causes the slip teeth 10 to penetrate into the inner wall of the casing 16 to form an anchor, ensuring the sealing state of the radial expansion deformation of the soluble seal in contact with the inner wall of the casing 16. Figure 5 As shown; wherein, the slip seat 9 can be a spiral slip seat, one end of which is a continuous structure and the other end can be squeezed open, and this form of slip is the prior art.

[0028] Release process: By applying a larger axial force to the shearing component, the shearing component is cut off, and the release lever 3 separates from the lower connector 11; as shown... Figure 6 As shown, when the shearing component is on the shearing disc 13, the shearing disc 13 will be pulled off at the right end of the lower connector, and the shearing disc 13 can be pulled out by the release lever 3.

[0029] Fracturing and perforation process: By pulling back the release rod 3, the release rod 3, adapter joint 15, and pusher 2 can be pulled back to the surface. During the pullback process, the tool string performs perforation; then, the fracturing ball 17 is sent into the well and sits at the central through hole of the soluble central cone 4, as shown. Figure 6 As shown, the soluble central cone 4 has an inner conical surface, which allows the fracturing ball 17 to sit better at the inner conical surface; after sitting, the soluble central cone 4 moves to the right under pressure to tighten the rubber ring, and fracturing operation can be carried out.

[0030] After continuous wellbore setting and fracturing / perforation operations involving soluble temperature-sensing bridge plugs, the soluble central cone 4, soluble seals, slips, and lower connector 11 need to be dissolved using flowback fluid before normal production operations can commence. The dissolution time of these components affects the start time of production operations. In this embodiment, both the soluble central cone 4 and the lower connector 11 are equipped with a temperature sensor 6. "Equipped" means that the temperature sensor 6 remains attached to the soluble central cone 4 and lower connector 11 throughout the wellbore setting, setting, release, fracturing, and perforation processes until they are completely dissolved. This allows for simultaneous and separate temperature measurements of both the soluble central cone 4 and the lower connector 11, enabling separate... By obtaining the temperature-time curves at the locations of the soluble central cone 4 and the lower connector 11, the relationship between temperature and dissolution at these locations can be determined. This relationship can then be used to select the materials for the soluble central cone 4 and the lower connector 11, resulting in shorter and more similar dissolution times for both, thus ensuring faster well production. This configuration allows for the analysis of temperature-time curves within the interval between the soluble central cone 4 and the lower connector 11, eliminating the need for temperature sensors 6 on the slips and soluble seals. This information can then be used for material selection of the slips and soluble seals, thereby reducing the number of temperature sensors 6 required.

[0031] As a preferred option, the soluble central cone 4 carries at least three thermometers 6, and all the thermometers 6 on the soluble central cone 4 are evenly arranged around the circumference of the soluble central cone 4; and / or, the lower connector 11 carries at least three thermometers 6, and all the thermometers 6 on the lower connector 11 are evenly arranged around the circumference of the lower connector 11. By arranging them evenly around the circumference, it is possible to measure the temperature better and to make temperature comparisons to obtain a more accurate relationship between temperature and dissolution rate.

[0032] Furthermore, both the soluble central cone 4 and the lower connector 11 are equipped with three thermometers 6. This ensures that the temperature at different circumferential positions can be measured while avoiding the need for an excessive number of thermometers 6. The three thermometers 6 on the soluble central cone 4 and the lower connector 11 are correspondingly arranged, which allows for better comparative analysis and is beneficial for the selection of materials for the soluble central cone 4 and the lower connector 11.

[0033] In an optional embodiment, the thermometer 6 can be fixed to the soluble central cone 4 and the lower connector 11, forming a carrying relationship; alternatively, a receiving groove can be provided on the soluble central cone 4 and the lower connector 11, with the thermometer 6 disposed in the receiving groove. The opening of the receiving groove is sealed by a sealing head 5, such as a sealing ring on the side wall of the sealing head 5, which can form a seal. In this embodiment, a gauge-protecting tooth 14 can also be provided on the outside of the lower connector 11. The gauge-protecting tooth 14 is radially arranged, and its outer end protrudes further outward than the outer end of the initial slip tooth 10, to avoid wear between the slip tooth 10 and the casing 16 during the well running process, thus reducing the loss of the slip tooth's anchoring capacity. Since the gauge-protecting tooth 14 occupies the axial portion of the lower connector 11, and the right end of the lower connector 11 is conical, insufficient to radially provide a receiving groove, to avoid axial growth, the receiving groove is provided on the end face of the lower connector 11 away from the soluble central cone 4, arranged axially, such as... Figure 6 As shown, in an optional embodiment, since the left end of the soluble central cone 4 is provided with an inner conical surface, a receiving groove is provided on the outer side of the opposite end of the soluble central cone 4 which is provided with an outer conical surface 41. The receiving groove is radially arranged, which makes it more convenient to set and avoids axially lengthening the soluble central cone 4.

[0034] In optional implementations, such as Figure 1 and Figure 2 As shown, the soluble temperature measuring bridge plug also includes a connecting tube 12. The release lever 3 passes through the central through hole of the connecting tube 12. One end of the soluble central cone 4 near the lower connector 11 is sleeved on the outside of the connecting tube 12. A limiting structure is provided on the inner side of the lower connector 11 and the outer side of the connecting tube 12. The limiting structure can restrict the lower connector 11 from moving away from the soluble central cone 4 relative to the connecting tube 12. Figure 2 As shown, the limiting structure consists of a limiting groove 111 located inside the lower connector 11 and a limiting protrusion 121 located outside the connecting pipe 12. Figure 1 and Figure 2 As shown, the outer side of the connecting pipe 12 and the inner side of the soluble central cone 4 are provided with matching anti-retraction teeth 122, which can restrict the movement of the connecting pipe 12 relative to the soluble central cone 4 towards the lower connector 11. Figure 2As shown, the longitudinal section of the anti-retraction tooth 122 is triangular or trapezoidal, and the side of the longitudinal section of the anti-retraction tooth 122 away from the lower connector 11 is an inclined surface. During setting, the lower connector 11 is close to the soluble central cone 4. After the shearing element between the release lever 3 and the lower connector 11 is sheared, the anti-retraction action of the anti-retraction tooth 122 and the limiting structure can maintain the relative position of the lower connector 11 and the soluble central cone 4, preventing them from separating. This allows for the analysis of the temperature-time curve of the interval between the soluble central cone 4 and the lower connector 11, without the need to install temperature sensors 6 on the slips and the soluble seal, thus reducing the number of temperature sensors 6 required.

[0035] In this embodiment, the thermometer 6 is preferably constructed to resist corrosion by well fluid. After the soluble central cone 4 and lower connector 11 dissolve, the well fluid can be returned to the outside of the well, allowing the temperature and time correlation data recorded within the thermometer 6 to be retrieved. This thermometer 6 has temperature measurement and storage functions and can record the relationship between time and temperature. The thermometer tooling principle is as follows: 1. During the dissolution of the bridge plug, heat is continuously released, generating heat. The thermometer can collect the heat data of the bridge plug. 2. The dissolution status of the bridge plug downhole can be determined based on different temperatures. As a preferred embodiment, the outer shell of the thermometer 6 is made of stainless steel, which is resistant to well fluid corrosion and not easily damaged.

[0036] The soluble thermometric bridge plug described in this embodiment can better detect the temperature of the bridge plug downhole, understand the impact of temperature changes on the dissolution rate, and understand the temperature comparison of different operating conditions and different materials at the same time. The temperature feedback data can provide a data basis for the next step of dissolution and material selection. Thus, while keeping other parts unchanged, different dissolution requirements can be met by changing some parts.

[0037] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A soluble temperature measuring bridge plug, comprising a release lever (3), a soluble central cone (4), a soluble sealing element, a slip, and a lower connector (11), wherein the release lever (3) passes sequentially through the central through hole of the soluble central cone (4), the slip, and the lower connector (11) and is connected to the lower connector (11) via a radially arranged shearing element; the soluble central cone (4) has an outer conical surface (41) at one end near the lower connector (11), the outer diameter of the outer conical surface (41) at one end near the lower connector (11) is smaller than the outer diameter at the other end; the soluble sealing element is sleeved on the outside of the outer conical surface (41); one end of the slip abuts against the soluble sealing element and the other end abuts against the lower connector (11); both the soluble sealing element and the slip are movable along the outer conical surface (41) toward the end away from the lower connector (11); characterized in that, Both the soluble central cone (4) and the lower connector (11) are equipped with thermometers (6).

2. The soluble thermometric bridge plug according to claim 1, characterized in that, The soluble central cone (4) carries at least three thermometers (6), and all the thermometers (6) on the soluble central cone (4) are evenly arranged around the circumference of the soluble central cone (4). And / or, The lower connector (11) carries at least three thermometers (6), and all the thermometers (6) on the lower connector (11) are evenly arranged around the lower connector (11).

3. The soluble thermometric bridge plug according to claim 2, characterized in that, The soluble central cone (4) and the lower connector (11) each carry three thermometers (6), and the three thermometers (6) on the soluble central cone (4) and the lower connector (11) are arranged correspondingly.

4. The soluble thermometric bridge plug according to claim 1, characterized in that, The lower connector (11) is provided with a diameter-protecting tooth (14) on its outer side. The lower connector (11) is provided with a receiving groove at one end face away from the soluble central cone (4). The thermometer (6) is placed in the receiving groove. The opening of the receiving groove is sealed by a sealing head (5).

5. A soluble thermometric bridge plug according to claim 1, characterized in that, The soluble central cone (4) has an outer conical surface (41) with a receiving groove on the opposite side. The thermometer (6) is placed in the receiving groove, and the opening of the receiving groove is sealed by a plug (5).

6. A soluble thermometric bridge plug according to any one of claims 1-5, characterized in that, It also includes a connecting tube (12), the release lever (3) passes through the central through hole of the connecting tube (12), the end of the soluble central cone (4) near the lower connector (11) is sleeved on the outside of the connecting tube (12), the inner side of the lower connector (11) and the outer side of the connecting tube (12) are provided with a limiting structure, the limiting structure can restrict the lower connector (11) from moving away from the soluble central cone (4) relative to the connecting tube (12), the outer side of the connecting tube (12) and the inner side of the soluble central cone (4) are provided with matching anti-retraction teeth (122), the anti-retraction teeth (122) can restrict the connecting tube (12) from moving towards the lower connector (11) relative to the soluble central cone (4).

7. A soluble thermometric bridge plug according to claim 6, characterized in that, The longitudinal section of the anti-retraction tooth (122) is triangular or trapezoidal, and the side of the longitudinal section of the anti-retraction tooth (122) away from the lower connector (11) is an inclined surface.

8. A soluble thermometric bridge plug according to claim 6, characterized in that, The limiting structure is a limiting groove (111) provided inside the lower connector (11) and a limiting protrusion (121) provided outside the connecting pipe (12).

9. A soluble thermometric bridge plug according to any one of claims 1-5, characterized in that, The outer shell of the thermometer (6) is made of stainless steel.

10. A soluble thermometric bridge plug according to any one of claims 1-5, characterized in that, The shearing component is a shearing disc (13) or a shearing pin; The soluble sealing element is a metal sealing ring or a rubber ring (8). When the soluble sealing element is a rubber ring (8), a pressure ring (7) is provided on the side of the rubber ring (8) away from the lower connector (11). The pressure ring (7) is sleeved on the outer cone surface (41) of the soluble central cone (4). The pressure ring (7) abuts against the adjacent end face of the rubber ring (8).

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