A corrosion-resistant wellhead gate valve for oil extraction

Abstract

This invention relates to the field of valve technology, and more specifically to a corrosion-resistant wellhead gate valve for oil extraction. It includes a gate valve body, within which a sealing screw gate plate is threadedly connected to form a sealing barrier. A space closure device and an inert gas injector are sealed within the sealing screw gate plate on the gate valve body. By adjusting the space closure device, a gas-sealed active space is formed between the sealing screw gate plate and the gate valve body. The inert gas injector adds inert gas to this gas-sealed active space to protect the sealing barrier. Both ends of the gate valve body are threadedly connected to oil pipelines. The beneficial effect of this invention is to solve the problem that conventional valves cannot effectively protect the sealing joint during oil extraction, and are also prone to corrosion and leakage in extreme corrosive environments such as high pressure, high temperature, hydrogen sulfide and carbon dioxide content, high-salinity formation water, and sand erosion.

Description

Technical Field

[0001] This invention relates to the field of valve technology, and more specifically to a corrosion-resistant wellhead gate valve for oil extraction. Background Technology

[0002] In oil extraction, wellhead gate valves are exposed to extreme corrosive environments such as high pressure, high temperature, formation water containing H2S / CO2, high salinity, and sand erosion for extended periods, making them highly susceptible to problems such as sulfide stress cracking (SSC), hydrogen-induced cracking (HIC), electrochemical corrosion, and erosion wear. Therefore, systematically setting and regulating gate valves is crucial for improving their corrosion resistance, extending their lifespan, and ensuring well control safety. A leak-proof wellhead gate valve for oil extraction, similar to one described in patent CN202310828152.X, includes a valve body, a support, and a valve stem. The valve body has a through-bore, and a vertically extending support is mounted on top of the valve body. A threaded valve stem is located within the support and can slide and rotate relative to the support. A gate plate is connected to the bottom of the valve stem and can move vertically along the through-bore of the valve body. A handwheel coaxially connects to the top of the valve stem and rotates with it. The valve stem also includes a filling mechanism, comprising a cylinder, a piston rod, and a gasket. The cylinder is located within the support and is parallel to the valve stem. This invention, through the design of the filling mechanism, can push the piston rod in the cylinder downward when the valve stem drives the gate to cut off the channel. This pushes the fluid in the cylinder along the connecting pipe to the rubber bladders on both sides of the gate, causing the rubber bladders to expand and fit tightly against the valve body, thereby strengthening the seal and preventing leakage. However, this valve cannot guarantee effective protection of the sealing joint during oil extraction. It is also prone to corrosion and leakage in extreme corrosive environments such as high pressure, high temperature, hydrogen sulfide and carbon dioxide, highly mineralized formation water, and sand erosion. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the fact that conventional valves in the prior art cannot effectively protect the sealing joints during oil extraction and are also prone to corrosion and leakage in extreme corrosive environments such as high pressure, high temperature, formation water containing H2S / CO2, high mineralization, and sand erosion.

[0004] Therefore, the technical solution adopted is a corrosion-resistant wellhead gate valve for oil extraction according to the present invention, including a gate valve body. A sealing screw gate plate is inserted into the gate valve body through threaded connection to form a sealing barrier. A space closure device and an inert gas injector are sealed on the gate valve body and connected to the sealing screw gate plate. By adjusting the space closure device, a gas-sealed active space is formed between the sealing screw gate plate and the gate valve body. Inert gas is added to the gas-sealed active space by the inert gas injector to protect the sealing barrier. Both ends of the gate valve body are sealed to oil pipelines through threaded connection.

[0005] Preferably, the upper end of the gate valve body is rotatably provided with an adjusting handwheel for threaded engagement to drive the sealing screw gate plate, the gate valve body is provided with an annular sealing extension seat at the medium flow direction closed end, the gate valve body is provided with a guide discharge hole penetrating the sealing extension seat, the guide discharge hole is connected to the discharge pipe, the discharge pipe is fixed on the gate valve body and is provided with a valve.

[0006] Preferably, both ends of the gate valve body and the oil pipeline are provided with pipeline sealing grooves, and sealing rings are provided in the pipeline sealing grooves; the inner wall of the gate valve body is provided with a fixed sealing seat for forming a sealing barrier with the sealing screw gate plate.

[0007] Preferably, the inner wall of the sealing extension stop is provided with a sealing groove.

[0008] Preferably, the sealing screw gate includes a screw, which is threadedly connected to an adjusting handwheel at the upper end of the gate valve body. An open gate seat is fixed at the lower end of the screw. An inner support pipe platform is provided in the opening of the open gate seat and fixed in the gate valve body. The open gate seat slides longitudinally within the gate valve body. A gate platform is fixed at the lower end of the open gate seat, and dynamic sealing seats are provided at both ends of the gate platform.

[0009] Preferably, the dynamic sealing seat and the fixed sealing seat are fitted together to form a sealing barrier.

[0010] Preferably, the inert gas injector includes an inert gas injecting pipe, an inert gas pressurization pipeline connected to the inert gas injecting pipe, the inert gas injecting pipe being fixed to the gate valve body and the inner support pipeline platform, the lower end of the inner support pipeline platform being fixed and connected to a sealing telescopic pipe, the inert gas injecting pipe being connected to the sealing telescopic pipe through the inner support pipeline platform, the sealing telescopic pipe being fixed and connected to a sealing gas connection seat, the sealing gas connection seat being fixed inside the gate valve platform, and multiple sealing gas connection seats being interconnected and connected to each other through an internal connecting pipe inside the gate valve platform.

[0011] Preferably, the side end of the sealed gas connection seat is sealed and slidably connected to the connecting slide, the connecting slide is fixed and connected within the space enclosure, and the space enclosure limits the sliding of the medium flow direction to the closed end of the gate platform.

[0012] Preferably, the space-sealing platform is provided with multiple gas-adding circular holes, all of which are connected to the sealing gas connection seat. The inner wall of the space-sealing platform is provided with an inner ring boss, which fits and seals with the sealing groove of the sealing extension seat. A gas-sealed active space is formed between the space-sealing platform and the sealing extension seat. Inert gas is added to the gas-sealed active space by pressurizing through the gas-adding circular holes.

[0013] Preferably, the space closure device includes a sealing telescopic screw, which rotates in a sealed manner within the gate valve body and the inner support pipe platform. The sealing telescopic screw is connected to a telescopic connecting plate via a threaded connection. The telescopic connecting plate slides within the inner support pipe platform and its lower end is fixed to a connecting rod extending from the space closure platform. Rotating the sealing telescopic screw drives the space closure platform to extend and retract within the gate platform.

[0014] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in this application.

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the integral valve connection pipeline of the present invention; Figure 2 This is a schematic diagram of the overall valve structure of the present invention; Figure 3 This is a schematic diagram of the gate valve body of the present invention; Figure 4 This is a cross-sectional schematic diagram of the gate valve body of the present invention; Figure 5 This is a partially enlarged cross-sectional structural diagram of the gate valve body of the present invention; Figure 6 This is a cross-sectional schematic diagram of the integral valve of the present invention; Figure 7 This is a schematic diagram of the structure of the sealing screw gate of the present invention; Figure 8 This is a cross-sectional schematic diagram of the sealing screw gate of the present invention; Figure 9 This is a schematic diagram of the gate platform of the present invention; Figure 10 This is a cross-sectional schematic diagram of the gate platform of the present invention; Figure 11 This is a schematic diagram of the connection structure between the space sealer and the inert gas adder of the present invention; Figure 12 This is a partial structural schematic diagram of the inert gas adder of the present invention; Figure 13 This is a schematic diagram of the structure of the space enclosure platform of the present invention; Figure 14 This is a schematic diagram of the driving structure of the space enclosure of the present invention; Figure 15 This is an enlarged cross-sectional view of the location of the gas-sealed active space of the present invention.

[0017] In the diagram: 1. Gate valve body; 2. Sealing screw gate; 3. Space closure device; 4. Inert gas injector; 5. Oil pipeline; 6. Adjusting handwheel; 7. Sealing extension stop; 8. Guide discharge hole; 9. Pipeline sealing groove; 10. Discharge pipe; 11. Fixed sealing seat; 12. Screw; 13. Open gate seat; 14. Gate platform; 15. Dynamic sealing seat; 16. Internal support pipeline platform; 17. Inert gas injector pipe; 18. Sealing telescopic pipe; 19. Sealing gas connection seat; 20. Internal connecting pipe; 21. Connecting slide; 22. Space closure platform; 23. Sealing telescopic screw; 24. Telescopic connecting plate; 26. Gas-sealed active space. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] In the description of this application, it should be understood that the terms "middle," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] Furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0022] Example 1: As Figure 1 and Figure 2 As shown, a corrosion-resistant wellhead gate valve for oil extraction includes a gate valve body 1. A sealing screw gate plate 2 is threadedly inserted into the gate valve body 1 to form a sealing barrier. A space closure device 3 and an inert gas injector 4 are sealed on the gate valve body 1 and connected to the sealing screw gate plate 2. By adjusting the space closure device 3, a gas-sealed active space 26 is formed between the sealing screw gate plate 2 and the gate valve body 1. Inert gas is added to the gas-sealed active space 26 by the inert gas injector 4 to protect the sealing barrier. Both ends of the gate valve body 1 are threadedly connected to oil pipelines 5.

[0023] The working principle and beneficial effects of this embodiment are as follows: Both ends of the gate valve body 1 are connected to the oil pipeline 5 via threaded joints, thereby adding the entire valve into the oil transportation pipeline for sealing and blocking. By adjusting and rotating the sealing screw gate plate 2 on the gate valve body 1 to form a sealing barrier, the transportation, sealing, blocking, and storage of oil in the pipeline are completed. A space closure device 3 and an inert gas injector 4 are sealed and connected to the sealing screw gate plate 2 for adjustment. By controlling and adjusting the rotation of the space closure device 3, a gas-sealed active space 26 is formed between the sealing screw gate plate 2 and the gate valve body 1. Then, the inert gas injector 4 adds inert gas into the gas-sealed active space 26 to protect the sealing barrier. By adding a complete annular inert gas to isolate the sealing area, the corrosion and impact on the sealing area are effectively reduced by extreme corrosive environments such as high pressure, high temperature, H2S / CO2 content, high-mineralization formation water, and sand erosion. Gas circulation is achieved through an external gas pressurization device and exhaust gas diversion. This allows for selection of continuous flow, closed-block storage, or intermittent gas addition protection methods based on actual usage conditions and sealing status. This solves the problem of insufficient protection for the sealing joint during oil extraction, which is also prone to corrosion and leakage in extreme corrosive environments such as high pressure, high temperature, H2S / CO2 content, high-mineralization formation water, and sand erosion.

[0024] Based on Example 1, further examples include... Figure 1 — Figure 15 As shown, a corrosion-resistant wellhead gate valve for oil extraction is provided. The upper end of the gate valve body 1 is rotatably provided with an adjusting handwheel 6 for threaded engagement to drive the sealing screw gate plate 2. An annular sealing extension seat 7 is provided inside the gate valve body 1 at the closed end where the medium flows. A guide discharge hole 8 is provided on the gate valve body 1, penetrating the sealing extension seat 7. The guide discharge hole 8 is connected to a discharge pipe 10. The discharge pipe 10 is fixed on the gate valve body 1 and is provided with a valve.

[0025] The working principle and beneficial effects of this embodiment are as follows: Rotating the adjusting handwheel 6, and then driving the sealing screw gate plate 2 to adjust up and down in the gate valve body 1 through the threaded engagement, so as to realize the adjustment and blocking of the conventional gate valve. Similarly, in order to prevent leakage, sealing rings or sealing rings and labyrinth seals are provided at the connection positions for filling and sealing. An annular sealing extension seat 7 is provided at the closed end of the gate valve body 1 for the medium flow, and a guide discharge hole 8 is provided on the gate valve body 1 through the sealing extension seat 7. The guide discharge hole 8 is connected to the discharge pipe 10. The discharge pipe 10 is connected to a vacuum pipeline or a guide pump to achieve flow guidance. The gas addition device with negative pressure promotes the circulation of the added inert gas, and some of the mixed petroleum is discharged, promoting the circulation of inert gas. The discharge pipe 10 is fixed on the gate valve body 1 and equipped with a valve to close when flow guidance is not required, thereby preventing the inert gas from flowing out. This effectively protects the sealing and blocking position, prevents corrosion caused by harsh environments, effectively reduces the impact of corrosion, and extends the service life through reasonable protection and operation.

[0026] Based on Example 1, further examples include... Figure 1 — Figure 15 As shown, a corrosion-resistant wellhead gate valve for oil extraction is provided at both ends of the gate valve body 1 and the oil pipeline 5, and a sealing ring is provided in the pipeline sealing groove 9; a fixed sealing seat 11 is provided on the inner wall of the gate valve body 1 to form a sealing block with the sealing screw gate plate 2.

[0027] The working principle and beneficial effects of this embodiment are as follows: Pipe sealing grooves 9 are provided at both ends of the gate valve body 1 and the oil pipeline 5. A sealing ring is provided in the pipe sealing groove 9, so that the external connection is sealed when connected to the oil pipeline 5. A fixed sealing seat 11 is provided on the inner wall of the gate valve body 1 to form a sealing block with the dynamic sealing seat 15 of the sealing screw gate plate 2, so as to realize the functions of the gate valve in the oil pipeline 5 for interception, transportation, storage and pressure reduction.

[0028] Based on Example 1, further examples include... Figure 1 — Figure 15As shown, a corrosion-resistant wellhead gate valve for oil extraction is provided with a sealing groove on the inner wall of the sealing extension seat 7.

[0029] The working principle and beneficial effects of this embodiment are as follows: the sealing extension stop 7 is annular in shape, and a sealing groove is provided on its inner wall to facilitate its adaptation to the shape of the space enclosure platform 22, thereby achieving effective sealing and blocking by increasing the contact area.

[0030] Based on Example 1, further examples include... Figure 1 — Figure 15 As shown, a corrosion-resistant wellhead gate valve for oil extraction includes a sealing screw gate 2 comprising a screw 12, which is threadedly connected to an adjusting handwheel 6 at the upper end of the gate valve body 1. An open gate seat 13 is fixed to the lower end of the screw 12. An inner support pipe platform 16 is provided within the opening of the open gate seat 13 and fixed inside the gate valve body 1. The open gate seat 13 slides longitudinally within the gate valve body 1. A gate platform 14 is fixed to the lower end of the open gate seat 13, and dynamic sealing seats 15 are provided at both ends of the gate platform 14. The dynamic sealing seats 15 and the fixed sealing seats 11 fit together to form a sealing barrier.

[0031] The working principle and beneficial effects of this embodiment are as follows: by rotating the adjusting handwheel 6, the screw 12 is rotated and threadedly connected to the gate valve body 1, thereby driving the lower end of the screw 12 to adjust the vertical displacement of the open gate seat 13. An inner support pipe platform 16 is provided in the opening of the open gate seat 13 to prevent unnecessary interference during vertical displacement. The inner support pipe platform 16 is fixed in the gate valve body 1, which facilitates the connection and adjustment of the space closure device 3 and the inert gas injector 4. The gate seat 13 is longitudinally limited and slids within the valve body 1 by a limiting slider. A gate platform 14 is fixed at the lower end of the gate seat 13, thereby driving the gate platform 14 to move up and down for adjustment. The downward gate platform 14 is inserted into the valve body 1 to block the flowing medium. Dynamic sealing seats 15 are provided at both ends of the gate platform 14. When the dynamic sealing seat 15 is tightly fitted with the fixed sealing seat 11 provided on the inner wall of the valve body 1 to form a sealing barrier, the sealing effect is achieved by the downward pressure. However, in the harsh environment of oil transportation for a long time, in order to avoid leakage and damage and cumbersome replacement, it is necessary to effectively protect the sealing barrier and reduce the corrosion rate.

[0032] Based on Example 1, further examples include... Figure 1 — Figure 15As shown, a corrosion-resistant wellhead gate valve for oil extraction includes an inert gas injector 4 comprising an inert gas injector pipe 17 connected to an inert gas pressurization pipeline. The inert gas injector pipe 17 is fixed to the gate valve body 1 and the inner support pipeline platform 16. The lower end of the inner support pipeline platform 16 is fixed and connected to a sealing telescopic pipe 18. The inert gas injector pipe 17 is connected to the sealing telescopic pipe 18 through the inner support pipeline platform 16. The sealing telescopic pipe 18 is fixed and connected to a sealing gas connection seat 19, which is fixed inside the gate plate platform 14. Multiple sealing gas connection seats 19 are interconnected and connected to each other through an internal connecting pipe 20 inside the gate plate platform 14.

[0033] The working principle and beneficial effects of this embodiment are as follows: External inert gas is added via the inert gas adding pipe 17 of the inert gas adder 4. The inert gas adding pipe 17 is connected to an external inert gas pressurization pipeline or a device for directly adding pressurized inert gas. The inert gas adding pipe 17 is connected to a sealed telescopic pipe 18 via an internal support pipe platform 16, thereby adding inert gas into the sealed telescopic pipe 18. The sealing structure of the telescopic pipe 18 facilitates the avoidance of unnecessary pipeline interference during vertical displacement. By fixing and connecting the sealed telescopic pipe 18 to the sealed gas connection seat 19, inert gas is added through the sealed gas connection seat 19. The sealed gas connection seat 19 is fixed within the gate platform 14 for support and to prevent fluctuations. Multiple sealed gas connection seats 19 are interconnected via internal connecting pipes 20 within the gate platform 14, thereby distributing and transferring inert gas. The pressurized inert gas is then added to the space-enclosed platform 22, and finally, the gas is added to the gas-enclosed active space 26 via the space-enclosed platform 22.

[0034] Based on Example 1, further examples include... Figure 1 — Figure 15 As shown, a corrosion-resistant wellhead gate valve for oil extraction is provided. The side end of the sealing gas connection seat 19 is sealed and slidably connected to the connecting slide seat 21. The connecting slide seat 21 is fixed and connected within the space enclosure platform 22. The space enclosure platform 22 limits the sliding of the medium flow direction to the closed end of the gate plate platform 14.

[0035] The working principle and beneficial effects of this embodiment are as follows: Because the side end of the sealed gas connector 19 is sealed and slidably connected to the slide 21, it is fixed and connected to the space enclosure platform 22 through the connecting slide 21, thereby allowing pressurized inert gas to be added to the space enclosure platform 22. Through the side end of the sealed gas connector 19 being sealed and slidably connected to the slide 21, the space enclosure platform 22 can add gas when it is sealed with the sealing extension stop 7 to form a gas-sealed active space 26. It can also retract into the gate platform 14, and cooperate with the gate valve to retract, so that the pipeline is connected and interference is prevented during use.

[0036] Based on Example 1, further examples include... Figure 1 — Figure 15 As shown, a corrosion-resistant wellhead gate valve for oil extraction is provided. The space-sealing platform 22 is provided with multiple gas-adding round holes, all of which are connected to the sealing gas connection seat 19. The inner wall of the space-sealing platform 22 is provided with an inner ring boss, which fits and seals with the sealing groove of the sealing extension seat 7. A gas-sealed active space 26 is formed between the space-sealing platform 22 and the sealing extension seat 7. The gas-sealed active space 26 is pressurized and inert gas is added through the gas-adding round holes.

[0037] The working principle and beneficial effects of this embodiment are as follows: Multiple gas-adding circular holes are provided on the space-sealing platform 22, and these holes are connected to the sealing gas connector 19 via the connecting slide 21, thereby achieving uniform and dispersed addition of pressurized gas, facilitating better and more even distribution within the annular gas-sealed active space 26. An inner annular protrusion is provided on the inner wall of the space-sealing platform 22, which fits and seals against the sealing groove of the sealing extension stop 7. This ensures that the space-sealing platform 22 fits and seals against the sealing groove of the sealing extension stop 7 during extension, completing the first step of sealing the space and forming the gas-sealed active space 2. 6. However, under high pressure, its sealing effect is negligible. Therefore, it is only for the purpose of having a gas-sealed active space 26 to facilitate the addition of gas and to limit the position of inert gas addition and protection. Inert gas that is too dispersed is ineffective. By limiting a gas space, the sealing barrier formed by the fixed sealing seat 11 and the dynamic sealing seat 15 of the sealing screw gate 2 can be effectively protected, preventing it from directly contacting the harsh medium being transported and causing direct corrosion. Over time, with frequent valve opening, the sealing barrier is easily damaged, causing leakage. It is necessary to replace the valve and seal, resulting in unnecessary economic losses such as pipeline shutdown. By forming a gas-sealed active space 26 between the space-sealed platform 22 and the sealing extension seat 7, inert gas is added to the gas-sealed active space 26 under pressure through a gas adding hole, thereby making the added inert gas form a ring within the gas-sealed active space 26, thus effectively protecting the sealing barrier.

[0038] Based on Example 1, further examples include... Figure 1 — Figure 15 As shown, a corrosion-resistant wellhead gate valve for oil extraction includes a space closure device 3 comprising a sealing telescopic screw 23, which rotates in a sealed manner within the gate valve body 1 and the inner support pipe platform 16. The sealing telescopic screw 23 is connected to a telescopic connecting plate 24 via a threaded connection. The telescopic connecting plate 24 slides within the inner support pipe platform 16, and its lower end is fixed to a connecting rod extending from the space closure platform 22. Rotating the sealing telescopic screw 23 drives the space closure platform 22 to extend and retract within the gate plate platform 14.

[0039] The working principle and beneficial effects of this embodiment are as follows: By synchronously rotating the two sealing telescopic screws 23 of the space closure device 3, the sealing telescopic screws 23 rotate within the gate valve body 1 and the inner support pipe platform 16, thus preventing overflow and leakage. The sealing telescopic screws 23 are connected to the telescopic connecting plate 24 through threaded engagement, thereby adjusting the telescopic connecting plate 24 to slide within the inner support pipe platform 16 for telescopic movement. The lower end is fixed to the connecting rod extending from the space closure platform 22, thereby adjusting the telescopic position of the space closure platform 22. By rotating the sealing telescopic screws 23, the space closure platform 22 is driven to telescopically move within the gate platform 14. After completing the sealing and blocking, the extended space closure platform 22 fits into the sealing groove of the sealing extension stop 7. A sealed, gas-enclosed active space 26 is created. The inert gas dispenser 4 pressurizes the inert gas, which, in conjunction with the guide discharge hole 8 and discharge pipe 10, facilitates the removal of residual petroleum from the gas-enclosed active space 26, completing the annular addition of inert gas. The gas-enclosed active space 26 facilitates gas addition and limits the location of inert gas addition protection. Inert gas that is too dispersed is ineffective. By limiting the gas space, the sealing barrier formed by the fixed sealing seat 11 and the dynamic sealing seat 15 of the sealing screw gate 2 can be effectively protected. At the same time, residual petroleum inside is discharged and isolated by gas. As the usage time increases, the protection of inert gas addition can continue by replenishing gas or guiding the flow.

[0040] The above description is not intended to limit the present invention, nor is the present invention limited to the examples given above. Any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the present invention are also within the protection scope of the present invention.

Claims

1. A corrosion-resistant wellhead gate valve for oil extraction, characterized in that: The valve includes a gate valve body (1), in which a sealing screw gate plate (2) is inserted and threaded to form a sealing barrier. A space closure device (3) and an inert gas injector (4) are sealed on the gate valve body (1). The space closure device (3) and the inert gas injector (4) are connected inside the sealing screw gate plate (2). By adjusting the space closure device (3), a gas-sealed active space (26) is formed between the sealing screw gate plate (2) and the gate valve body (1). Inert gas is added to the gas-sealed active space (26) by the inert gas injector (4) to protect the sealing barrier. Both ends of the gate valve body (1) are sealed and connected to oil pipelines (5) by threaded connection. The gate valve body (1) is provided with an annular sealing extension seat (7). The sealing extension seat (7) is located at the closed end of the medium flow direction. The gate valve body (1) is provided with a guide discharge hole (8) that passes through the sealing extension seat (7). The guide discharge hole (8) is connected to the discharge pipe (10). The discharge pipe (10) is fixed on the gate valve body (1) and is provided with a valve. The sealing screw gate (2) includes a screw (12), and an open gate seat (13) is fixed at the lower end of the screw (12). An inner support pipe platform (16) is provided in the opening of the open gate seat (13) and fixed in the gate valve body (1). The open gate seat (13) slides longitudinally within the gate valve body (1). A gate platform (14) is fixed at the lower end of the open gate seat (13). Both ends of the gate platform (14) are provided with dynamic sealing seats (15). The dynamic sealing seat (15) and the fixed sealing seat (11) fit together to form a sealing barrier; The inert gas injector (4) includes an inert gas injector pipe (17), which is connected to an inert gas pressurization pipeline. The inert gas injector pipe (17) is fixed on the gate valve body (1) and the inner support pipeline platform (16). The lower end of the inner support pipeline platform (16) is fixed and connected to the sealing telescopic pipe (18). The inert gas injector pipe (17) is connected to the sealing telescopic pipe (18) through the inner support pipeline platform (16). The sealing telescopic pipe (18) is fixed and connected to the sealing gas connection seat (19). The sealing gas connection seat (19) is fixed inside the gate platform (14). Multiple sealing gas connection seats (19) are connected to each other through the internal connecting pipe (20) inside the gate platform (14). The space closure device (3) includes a sealing telescopic screw (23), which rotates in a sealed manner within the gate valve body (1) and the inner support pipe platform (16). The sealing telescopic screw (23) is connected to the telescopic connecting plate (24) by a threaded connection. The telescopic connecting plate (24) slides within the inner support pipe platform (16). The lower end of the inner support pipe platform (16) is fixed to the connecting rod extending from the space closure platform (22). By rotating the sealing telescopic screw (23), the space closure platform (22) is driven to extend and retract within the gate platform (14).

2. The corrosion-resistant wellhead gate valve for oil extraction according to claim 1, characterized in that: The upper end of the gate valve body (1) is rotatably provided with an adjusting handwheel (6) for threaded engagement to drive the sealing screw gate plate (2).

3. A corrosion-resistant wellhead gate valve for oil extraction according to claim 2, characterized in that: Both ends of the gate valve body (1) and the oil pipeline (5) are provided with pipeline sealing grooves (9), and sealing rings are provided in the pipeline sealing grooves (9); the inner wall of the gate valve body (1) is provided with a fixed sealing seat (11) for forming a sealing block with the sealing screw gate plate (2).

4. A corrosion-resistant wellhead gate valve for oil extraction according to claim 2, characterized in that: The inner wall of the sealing extension stop (7) is provided with a sealing groove.

5. A corrosion-resistant wellhead gate valve for oil extraction according to claim 3, characterized in that: The screw (12) is connected to the adjusting handwheel (6) at the upper end of the gate valve body (1) by a threaded connection.

6. A corrosion-resistant wellhead gate valve for oil extraction according to claim 1, characterized in that: The side end of the sealed gas connection seat (19) is sealed and slidably connected to the connecting slide (21). The connecting slide (21) is fixed and connected in the space closed platform (22). The space closed platform (22) limits the medium flow to the closed end of the gate platform (14).

7. A corrosion-resistant wellhead gate valve for oil extraction according to claim 6, characterized in that: The space-sealed platform (22) is provided with multiple gas-adding round holes that are all connected to the sealing gas connection seat (19). The inner wall of the space-sealed platform (22) is provided with an inner ring boss, which fits and seals with the sealing groove of the sealing extension seat (7). A gas-sealed active space (26) is formed between the space-sealed platform (22) and the sealing extension seat (7). The gas-sealed active space (26) is pressurized and inert gas is added through the gas-adding round holes.

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