Wellhead temporary closure device and wellhead main gate replacement method

Abstract

This invention discloses a wellhead temporary closure device and a method for replacing the wellhead main gate valve. The wellhead temporary closure device includes a release and retrieval mechanism, an anchoring mechanism fixed to the release end of the release and retrieval mechanism, an expansion and sealing mechanism fixed to the end of the anchoring mechanism away from the release and retrieval mechanism, a setting ball fixed to the end of the expansion and sealing mechanism away from the anchoring mechanism, and a one-way valve fixed to the end of the setting ball fixed to the end of the expansion and sealing mechanism away from the expansion and sealing mechanism. The wellhead main gate valve replacement method includes S1, lowering the device into the well; S2, anchoring and sealing; S3, anchoring verification; S4, depressurizing the device; S5, releasing the device; S6, sealing verification; S7, replacing the main gate valve; and S8, retrieving the device. This invention can anchor and seal the wellhead through the wellhead main valve with a small opening stroke, and can quickly and cost-effectively replace the wellhead main gate valve, making it suitable for replacing wellhead main gate valves.

Description

Technical Field

[0001] This invention relates to a wellhead temporary sealing device and method, specifically a wellhead temporary sealing device and method that can pass through a narrow gate and temporarily seal the wellhead. Background Technology

[0002] In the process of oil and gas field development, the wellhead main gate valve is a very important well control device. Due to human, environmental and other factors, the wellhead main gate valve often fails, resulting in the wellhead main gate valve not being able to be fully opened. In this case, the wellhead main gate valve must be replaced before downhole operations can continue.

[0003] Currently, the main method for replacing the wellhead main gate valve is to first set the wellhead with a bridge plug before replacing the main gate valve. However, when the damage to the wellhead main gate valve is so severe that the opening stroke is only 90mm, the bridge plug, whose outer diameter is usually over 109mm, cannot be lowered into the well through the main gate valve due to its large size. In this case, the only options are to use a pressurized working device to drill open the wellhead main gate valve or to apply a cryogenic temporary plugging process. While these two methods can replace the wellhead main gate valve, they also result in a longer construction period and higher construction costs. Summary of the Invention

[0004] To address the aforementioned shortcomings in the existing technology, this invention aims to provide a wellhead temporary closing device and method, which can pass through the wellhead main gate with a small opening stroke to seal the wellhead and enable the rapid replacement of the wellhead main gate.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A wellhead temporary closure device includes a release and retrieval mechanism, an anchoring mechanism, an expansion packer mechanism, a setting ball seat, and a one-way valve. The release and retrieval mechanism, the anchoring mechanism, the expansion packer mechanism, the setting ball seat, and the one-way valve are connected end to end in sequence to form a columnar tool string that can pass through the failed wellhead main gate. The drop-and-retrieve mechanism includes a first central tube, a first upper connector, a sealing sleeve, a drop-and-retrieve component, and a first lower connector; wherein the first upper connector and the sealing sleeve are respectively fixedly sleeved at both ends of the first central tube, the drop-and-retrieve component is movably sleeved in the middle of the first central tube, and the first lower connector is movably sleeved on the sealing sleeve and detachably connected to the drop-and-retrieve component. The anchoring mechanism includes an upper central tube, a lower central tube, a second upper connector, a slip assembly, a clamping assembly, a releasing assembly, and a second lower connector; wherein the outer diameter of the lower central tube is the same as the inner diameter of the upper central tube, and the lower central tube is fixedly inserted through one end of the upper central tube, the second upper connector is fixedly sleeved on the other end of the upper central tube, and the second upper connector is fixedly connected to the first lower connector. The clamping assembly is fixedly sleeved on the upper central tube, the loosening assembly is movably sleeved on the lower central tube, and the slip assembly is fixedly sleeved on the lower central tube. Both ends of the slip assembly are fixedly connected to the movable ends of the clamping assembly and the loosening assembly, respectively. The second lower connector is fixedly inserted through the end of the loosening assembly away from the slip assembly. The expansion packer mechanism includes a second central tube, a third upper connector, a packer assembly, and a third lower connector; wherein the third upper connector is fixedly sleeved on one end of the second central tube and is fixedly connected to the second lower connector, the third lower connector is fixedly sleeved on the other end of the second central tube, and the packer assembly is sleeved on the middle of the second central tube. The inlet end of the setting ball seat is fixedly connected to the third lower connector, and the outlet end of the setting ball seat is fixedly connected to the inlet end of the check valve.

[0006] As a limitation of the present invention, the drop-and-retrieve assembly includes a one-way locking ring, a first connecting sleeve, an elastic claw, a compression spring, and a slider; A one-way locking ring is installed on the first central tube, and the one-way locking ring can only move in the direction closer to the first upper connector. The first connecting sleeve is fixedly sleeved on the first central tube through a connector. The elastic claw and the compression spring are both movably sleeved on the first central tube, and the two ends of the compression spring are fixedly connected to the first connecting sleeve and the elastic claw, respectively. The slider is sleeved on the first central tube and fixedly connected to the claw end of the elastic claw. The first connecting sleeve is positioned on the side of the one-way locking ring away from the first upper connector. The first connecting sleeve covers the end of the compression spring and the elastic claw connected to the compression spring between the first connecting sleeve and the first central tube.

[0007] As a further limitation of the present invention, the clamping assembly includes a sealing limiting sleeve, a piston, a locking ring, and a high-pressure fluid communication hole; the sealing limiting sleeve is fixedly sleeved on the upper central tube, the piston is movably sleeved on the upper central tube, and the piston is located in the space enclosed by the sealing limiting sleeve and the upper central tube; the locking ring is sleeved on the piston, and the outer wall of the locking ring is fixedly connected to the sealing limiting sleeve; the high-pressure fluid communication hole is opened on the upper central tube, and the high-pressure fluid communication hole faces the space enclosed by the second upper connector, the sealing limiting sleeve, and the piston; The loosening assembly includes a limiting connecting sleeve, a return spring, a release ball seat, and a locking tooth block. The limiting connecting sleeve, return spring, and release ball seat are all movably sleeved on the lower central tube. The return spring and release ball seat are located in the space between the limiting connecting sleeve and the lower central tube. The two ends of the return spring are fixedly connected to the lower central tube and the limiting connecting sleeve, respectively, and the return spring is in a compressed state. The locking tooth block is movably sleeved on the lower central tube and fixedly connected to the release ball seat. The locking tooth block is unidirectionally locked in the direction close to the lower connecting tube. The slip assembly includes an upper connecting block, a lower connecting block, and a slip. The upper and lower connecting blocks are movably sleeved on the lower central tube, and the slip is fixedly sleeved on the lower central tube. The two movable ends of the slip are fixedly connected to the upper and lower connecting blocks, respectively. The other end of the upper connecting block is fixedly connected to the piston, and the other end of the lower connecting block is fixedly connected to the limiting connecting sleeve.

[0008] As a further limitation of the present invention, the sealing and limiting sleeve includes an upper outer cylinder and a connecting sleeve. The two ends of the upper outer cylinder are respectively fixedly connected to the second upper connector and one end of the connecting sleeve, and the other end of the connecting sleeve is fixedly connected to the locking ring. The limiting connecting sleeve includes an inner outer cylinder and a lower outer cylinder. The two ends of the inner outer cylinder are fixedly connected to the lower connecting block and one end of the lower outer cylinder, respectively. The other end of the lower outer cylinder is fixedly connected to the second lower connector. The reset spring is located in the space between the inner outer cylinder and the lower central tube. The unsealing ball seat is located in the space between the lower outer cylinder and the lower central tube. The length of the lower outer cylinder is greater than the length of the unsealing ball seat.

[0009] As another limitation of the present invention, the sealing assembly includes a control sleeve, a valve seat, a check piston, an upper sealing connecting sleeve, a limit spring, a lower sealing connecting sleeve, a rubber sleeve, an inlet, and an outlet. The control sleeve is movably fitted onto the second central tube and fixedly connected to the third upper head via a connector. The valve seat is fixedly fitted onto the second central tube. The check piston passes through the end of the valve seat away from the third upper connector. The upper sealing connecting sleeve and the lower sealing connecting sleeve are fixedly fitted onto the second central tube, and the upper sealing connecting sleeve covers the valve seat and the check piston. The limit spring is also covered in the upper sealing connecting sleeve, and both ends of the limit spring are fixedly connected to the check piston and the upper sealing connecting sleeve, respectively. The rubber sleeve is fixedly fitted onto the second central tube, and both ends of the rubber sleeve are fixedly connected to the upper sealing connecting sleeve and the lower sealing connecting sleeve, respectively. The inlet and outlet are both located on the second central tube for filling and discharging the rubber sleeve.

[0010] This invention also discloses a method for replacing the wellhead main gate, which specifically includes the following steps: S1. Lowering the device into the well: Lower the temporary well-closing device to the designated position inside the well; S2, Anchoring and Separation: Activate the anchoring and sealing mechanisms to complete the anchoring of the wellhead temporary closure device at the wellhead and the sealing of the wellhead; S3. Anchoring verification: Raise the wellhead temporary closure device to verify whether the anchoring is successful. If successful, proceed to the next step; otherwise, re-anchor. S4. Device depressurization: Continue to pressurize the device until the set ball seat is knocked off, thus completing the depressurization process; S5, Release: Press down the release retrieval component to release the anchoring mechanism, expansion sealing mechanism, setting ball seat and check valve; S6. Packer verification: Verify whether the packer is completely sealed by opening the casing gate and observing the overflow. If it is completely sealed, proceed to the next step. If it is not completely sealed, remove the device and put it back into the well. S7. Replace the main gate: Replace the faulty main gate at the wellhead; S8. Retrieval Device: Unanchor and depressurize the anchoring mechanism and expansion packer mechanism, and retrieve the wellhead temporary closure device using the drop-out retrieval assembly.

[0011] By adopting the above-described technical solution, the beneficial effects achieved by this invention compared to the prior art are as follows: (1) The present invention designs a wellhead temporary closing device that can pass through a narrow wellhead main gate and can seal the wellhead. By connecting the components of the present invention one by one in sequence to form a tubular tool string, the diameter of the present invention is minimized. At the same time, the present invention is provided with an anchoring mechanism and an expansion sealing mechanism. Both the anchoring mechanism and the expansion sealing mechanism will only anchor and expand sealing after pressure is applied. This ensures that the present invention has a small diameter and achieves the purpose of passing through a narrow wellhead main gate. It also enables the present invention to be anchored and sealed in the well after being lowered into the well.

[0012] (2) The retrieval assembly of the present invention is provided with a one-way locking ring and a compression spring, so that the elastic claw can remain in the position after being pressed down without rebounding, thereby completing the release of the latch between the elastic claw and the first lower connector.

[0013] (3) The clamping assembly of the present invention is provided with a locking ring, which can limit the piston to move only away from the second upper connector. When the piston is pushed by pressure to support the slip and complete the anchoring, the locking ring can prevent the piston from returning to its original position due to the loss of pressure, but always maintain the state of supporting the slip. Similarly, the sealing assembly is provided with a limiting spring and a check piston. When the pressure is stopped, the check piston will return to its original position under the action of the limiting spring to prevent the liquid in the rubber tube from flowing out, which makes it possible for the present invention to not need to continue to apply pressure after the anchoring and sealing are completed.

[0014] (4) The present invention is provided with a seated ball seat, which can not only ensure that the inside of the present invention can be pressurized, but also enable the present invention to complete the depressurization without removing the air injection tube, thus improving the working efficiency.

[0015] (5) The present invention is provided with a one-way valve, which can ensure that the pressure can only flow out from the inside of the present invention. When the pressure inside the well exceeds the inside of the present invention, the one-way valve can block it from entering the inside of the present invention.

[0016] (6) The present invention also designed a method for quickly replacing the main gate of the wellhead. By using the wellhead temporary sealing device to temporarily seal the wellhead, the main gate does not need to be replaced in a pressurized environment, which improves the replacement efficiency. At the same time, after the replacement is completed, the wellhead temporary sealing device can be retrieved and recovered, which reduces the replacement cost.

[0017] (7) In this invention, steps S3 and S6 respectively verified the anchoring and sealing, ensuring the stability of the anchoring and sealing, and avoiding the situation where the well pressure was not sealed during the replacement of the wellhead main valve, resulting in the replacement failure.

[0018] In summary, this invention can anchor and seal the wellhead through the main wellhead valve with a small opening stroke, and can quickly and cost-effectively replace the main wellhead gate valve, making it suitable for replacing the main wellhead gate valve. Attached Figure Description

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] Figure 1 This is a schematic diagram illustrating the usage state of an embodiment of the present invention; Figure 2 This is a half-sectional view of the retrieval mechanism in an embodiment of the present invention; Figure 3 This is a half-sectional view of the anchoring mechanism in an embodiment of the present invention; Figure 4 This is a half-sectional view of the expansion sealing mechanism in an embodiment of the present invention; Figure 5 This is a schematic diagram showing the connection relationship between the setting ball seat and the one-way valve in an embodiment of the present invention; Figure 6 This is a flowchart of a wellhead main gate replacement method according to an embodiment of the present invention; In the diagram: 1. Retrieval mechanism; 2. Anchoring mechanism; 3. Expansion and sealing mechanism; 4. Sealing ball seat; 5. Check valve; 11. First upper connector; 12. First central tube; 13. Left connecting sleeve; 14. One-way locking ring; 15. First pin; 16. Right connecting sleeve; 17. Compression spring; 18. Elastic claw; 19. Slider; 110. Sealing sleeve; 111. First lower connector; 21. Second upper connector; 22. Upper central tube; 23. Upper outer cylinder; 24. Second pin; 25. Piston; 26. Connecting sleeve; 27. Locking ring; 28. Fixing pin; 29. ​​Upper connecting block; 210. Locking slip; 211. Lower central tube; 212. Lower connecting block; 213. Middle outer cylinder; 214. Return spring seat; 215. Return spring; 216. Locking tooth block; 217. Lower outer cylinder; 218. Third pin; 219. Unsealing ball seat; 220. Unsealing boss; 221. Second lower connector; 2a. High-pressure fluid communication port 31. Third upper connector; 32. Second central tube; 33. Fourth pin; 34. Control sleeve; 35. Valve seat; 36. Check piston; 37. Limit spring; 38. Upper sealing connecting sleeve; 39. Rubber sleeve; 310. Lower sealing connecting sleeve; 311. Third lower connector; 3a. Liquid inlet; 3b. Liquid outlet. Detailed Implementation

[0021] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0022] This embodiment discloses a wellhead temporary closure device, such as Figures 1-5 As shown, it includes a retrieval mechanism 1, an anchoring mechanism 2, an expansion packer mechanism 3, a setting ball seat 4, and a one-way valve 5. The setting ball seat 4 and the one-way valve 5 are existing structures. The one-way valve 5 allows the liquid in the wellhead temporary closure device to flow into the well, but the liquid in the well cannot enter the wellhead temporary closure device.

[0023] I. Lost and retrieved organizations like Figure 2 As shown, the drop-and-retrieve mechanism 1 includes a first central tube 12, a first upper connector 11, a sealing sleeve 110, a drop-and-retrieve assembly, and a first lower connector 111; wherein the first upper connector 11 and the sealing sleeve 110 are respectively fixedly sleeved at both ends of the first central tube 12, the drop-and-retrieve assembly is movably sleeved in the middle of the first central tube 12, and the first lower connector 111 is movably sleeved on the sealing sleeve 110 and detachably connected to the drop-and-retrieve assembly.

[0024] The drop-and-retrieve assembly includes a one-way locking ring 14, a first connecting sleeve, an elastic claw 18, a compression spring 17, and a slider 19.

[0025] One-way locking ring 14 is installed on the first central tube 12. Matching teeth are provided on the side of the one-way locking ring 14 near the first central tube 12 and at the corresponding position of the first central tube 12 and the one-way locking ring 14, so that the one-way locking ring 14 can only move towards the first upper connector 11. The first connecting sleeve is fixedly sleeved on the first central tube. The elastic claw 18 and the compression spring 17 are both movably sleeved on the first central tube 12, and the two ends of the compression spring 17 are fixedly connected to the first connecting sleeve and the elastic claw 18 respectively. The slider 19 is sleeved on the first central tube 12 and fixedly connected to the claw end of the elastic claw 18.

[0026] In this embodiment, the first connecting sleeve includes a left connecting sleeve 13 fixedly connected to the first central tube 12 by a first pin 15 and a right connecting sleeve 16 fixedly sleeved on the left connecting sleeve 13. The two ends of the compression spring 17 are respectively fixed on the left connecting sleeve 13 and the elastic claw 18. The end of the elastic claw 18 connected to the compression spring 17 is located between the right connecting sleeve 16 and the first central tube.

[0027] When it is necessary to release the device, the first upper connector 11 needs to be pressed down. At the same time, the first upper connector 11 will press down the first central tube 12. Since the one-way locking ring 14 can only move towards the first upper connector 11, the first pin 15 between the first central tube 12 and the left connecting sleeve 13 will be sheared during the pressing process. Then, the first central tube 12 will drive the slider 19 and the elastic claw 18 to move down, so that the claw end of the elastic claw 18 disengages from the snap connection with the first lower connector 111 and enters the gap between the first lower connector 111 and the first central tube 12. At this time, due to the release of the compression spring 17, the elastic claw 18 will remain in the gap position between the first lower connector 111 and the first central tube 12 and remain in a loose state with the first lower connector 111. At this time, lifting the first upper connector 11 will complete the release of the first lower connector 111 and the remaining parts.

[0028] When retrieval is required, the first pin 15 that has been cut off needs to be replaced, and the compression spring 17 and elastic claw 18 need to be reset to the unreleased state. Then, the repaired parts are lowered into the well, and downward pressure is applied to make the elastic claw 18 snap into the first lower connector 111 again, and retrieval can then be carried out.

[0029] It should be added here that sealing rings are provided on both ends of the first central tube 12 and on the sealing sleeve 110. When liquid is introduced into the first central tube 12, the sealing rings can ensure that the liquid does not enter the components outside the first central tube 12.

[0030] II. Anchoring Mechanism like Figure 3As shown, the anchoring mechanism 2 includes an upper central tube 22, a lower central tube 211, a second upper connector 21, a slip assembly, a clamping assembly, a loosening assembly, and a second lower connector 221; wherein the outer diameter of the lower central tube 211 is the same as the inner diameter of the upper central tube 22, and the lower central tube 211 is fixedly inserted through one end of the upper central tube 22, the second upper connector 21 is fixedly sleeved on the other end of the upper central tube 22, and the second upper connector 21 is fixedly connected to the first lower connector 111.

[0031] The clamping assembly includes a sealing and limiting sleeve, a piston 25, a high-pressure fluid communication hole 2a, and a locking ring 27. The sealing and limiting sleeve includes an upper outer cylinder 23 and a connecting sleeve. Specifically: The upper outer cylinder 23 is fixedly sleeved on the second upper connector 21. The piston 25 is located between the upper outer cylinder 23 and the upper central tube 22 and is fixed on the upper central tube 22 by the second pin 24. The connecting sleeve 26 is sleeved on the piston 25 and fixed on the end of the upper outer cylinder 23 away from the second upper connector 21. The locking ring 27 is sleeved on the upper central tube 22 and fixed on the side of the connecting sleeve 26 near the piston 25 by the fixing pin 28. The locking ring 27 and the upper central tube 22 are fixed with matching teeth, so that the piston 25 can only move away from the second upper connector 21. The high-pressure fluid communication hole 2a is opened on the upper central tube 22 and is located between the second upper connector 21 and the piston 25.

[0032] The slip assembly includes an upper connecting block 29 fixedly sleeved on one end of the piston 25 away from the second upper connector 21, a slip 210 fixedly connected to the upper connecting block 29 at one end, and a lower connecting block 212 sleeved on the lower central tube 211 and fixedly connected to the other end of the slip 210. The release assembly includes an outer cylinder 213, a return spring seat 214, a return spring 215, a release ball seat 219, a locking tooth block 216, and a lower outer cylinder 217. The outer cylinder 213 is fixedly sleeved on the lower connecting block 212. The two ends of the return spring 215 are fixedly connected to the side of the return spring seat 214 away from the lower cone and the outer cylinder 213, respectively, and the return spring 215 is in a compressed state. The release ball seat 219 is sleeved on the lower central tube 211, and a locking tooth block 216 is fixedly mounted on the side of the release ball seat 219 facing the lower central tube 211. There is a release boss 220, a locking tooth block 216 is sleeved on the lower central tube 211 and fixedly connected to the side of the release ball seat 219 near the lower central tube 211, and there are matching teeth between the locking tooth block 216 and the lower central tube 211, so that the locking tooth block 216 can only move away from the lower cone. The lower outer cylinder 217 is sleeved on the outside of the release ball seat 219 and fixedly connected to the release ball seat 219 through the third pin 218, and the two ends of the lower outer cylinder 217 are fixedly connected to the middle outer cylinder 213 and the lower connector, respectively.

[0033] When anchoring is required, high-pressure liquid is first injected into the central tube. The high-pressure liquid enters the space between the upper outer cylinder 23 and the upper central tube 22 through the high-pressure fluid communication hole 2a on the upper central tube 22. At the same time, the high-pressure liquid pushes the piston 25 and shears the second pin 24 between the piston 25 and the upper central tube 22, allowing the piston 25 to move away from the second upper connector 21. This pushes the upper cone to squeeze the slip 210, causing the slip 210 to open to both sides for anchoring. Since the locking ring 27 restricts the movement of the piston 25 to only move away from the second upper connector 21, once the piston 25 pushes the upper cone to squeeze and anchor the slip 210, the slip 210 will always remain in the anchored state even if the high-pressure liquid stops entering.

[0034] When anchor release is required, an unsealing steel ball is first inserted into the upper central tube 22. The unsealing steel ball enters the lower central tube 211 through the upper central tube 22 and eventually reaches the unsealing boss 220. At this time, pressure is applied to the upper central tube 22, causing the unsealing steel ball to push the unsealing ball seat 219 through the unsealing boss 220 and shear the third pin 218 between the unsealing ball seat 219 and the lower outer cylinder 217, causing the unsealing ball seat 219 to move away from the lower cone. At the same time, the compressed return spring 215 will push the middle and outer cylinder 213 closer to the unsealing. The ball seat 219 is pushed in the direction, which in turn causes the lower cone to move towards the unsealing ball seat 219. At the same time, as the lower cone moves towards the unsealing ball seat 219, it will pull the slip 210 back from the squeezed state that is opening to both sides, thus completing the unanchoring. Furthermore, since the locking tooth block 216 restricts the movement of the unsealing ball seat 219 to only moving away from the lower cone, when the pressure on the unsealing steel ball stops, the unsealing ball seat 219 will remain in the unsealed position and will not spring back, so that the anchoring mechanism 2 is always in the unsealed state.

[0035] It should be noted that sealing rings are provided at the following locations: the contact points between the upper central tube 22 and the second upper connector 21, the contact points between the second upper connector 21 and the upper outer cylinder 23, the contact points between the upper central tube 22 and the piston 25, the contact points between the piston 25 and the upper outer cylinder 23, the contact points between the upper central tube 22 and the lower central tube 211, and the contact points between the lower central tube 211 and the unsealing ball seat 219. The sealing rings at the contact points between the second upper connector 21 and the upper outer cylinder 23 and between the upper central tube 22 and the piston 25 are used to prevent high-pressure liquid from flowing into the piston 25, so that the pressure provided by the high-pressure liquid can be fully applied to the piston 25. The sealing rings at other locations are used to prevent high-pressure liquid from flowing into the internal structure of the anchoring mechanism 2.

[0036] III. Expansion and Sealing Mechanism like Figure 4As shown, the expansion sealing mechanism 3 includes a second central tube 32, a third upper connector 31, a sealing assembly, and a third lower connector 311; wherein the third upper connector 31 is fixedly sleeved on one end of the second central tube 32 and is fixedly connected to the second lower connector 221, the third lower connector 311 is fixedly sleeved on the other end of the second central tube 32, and the sealing assembly is sleeved on the middle part of the second central tube 32.

[0037] In this embodiment, the sealing assembly includes a control sleeve 34, a valve seat 35, a check piston 36, an upper sealing connecting sleeve 38, a limiting spring 37, a lower sealing connecting sleeve 310, an inlet 3a, an outlet 3b, and a rubber sleeve 39. The control sleeve 34 is fitted onto the second central tube 32 and fixedly connected to the third upper connector 31 via a fourth pin 33. The valve seat 35 is fixedly fitted onto the second central tube 32. The check piston 36 passes through the end of the valve seat 35 away from the third upper connector 31. The upper sealing connecting sleeve 38... 8 is fixedly sleeved on the second central tube 32 and covers the valve seat 35 and the check piston 36 therein. The limit spring 37 is covered by the upper sealing connecting sleeve 38 and its two ends are fixed on the check piston 36 and the upper sealing connecting sleeve 38 respectively. The lower sealing connecting sleeve 310 is sleeved on the second central tube 32. The liquid inlet 3a and the liquid outlet 3b are both opened on the second central tube 32. The rubber sleeve 39 is sleeved on the second central tube 32 and its two ends are fixedly connected to the upper sealing connecting sleeve 38 and the lower sealing connecting sleeve 310 respectively.

[0038] It should be added here that: a sealing ring is fitted at the contact position between the second central tube 32 and the third upper connector 31 to prevent high-pressure liquid from flowing out; a sealing ring is fitted on the second central tube 32 next to the inlet 3a and close to the third upper connector 31 to restrict the high-pressure liquid from flowing into the inlet 3a and only towards the check piston 36; a sealing ring is fitted at the contact position between the valve seat 35 and the upper sealing connecting sleeve 38 to prevent high-pressure liquid leakage; a sealing ring is provided at the contact position between the check piston 36 and the upper sealing connecting sleeve 38 and the contact position between the second central tube 32 and the check piston 36 to prevent high-pressure liquid from flowing towards the rubber sleeve 39; and a sealing ring is embedded on the surface of the lower sealing connecting sleeve 310 facing the second central tube 32 and located on both sides of the outlet 3b to prevent high-pressure liquid from flowing out.

[0039] In actual use, high-pressure liquid is first introduced into the second central tube 32. The high-pressure liquid flows from the inlet 3a into the gap between the valve seat 35 and the check piston 36, pushing the check piston 36 to move away from the valve seat 35. As the check piston 36 continues to move until the sealing ring on the check piston 36 disengages from the upper sealing connection sleeve 38, the sealing ring at this point no longer has a sealing effect. The high-pressure liquid will continue to flow into the rubber sleeve 39, inflating and expanding the rubber sleeve 39. When the high-pressure liquid stops flowing in... When the pressure is released, the limit spring 37 will rebound and drive the check piston 36 back to its original position. At this time, the sealing ring on the check piston 36 will contact the upper sealing connecting sleeve 38 again to complete the seal, and the high-pressure liquid flowing into the rubber sleeve 39 will not be able to flow out, thus completing the isolation of the wellhead. When it is necessary to release the isolation, simply lift the second central tube 32 so that the outlet 3b on the second central tube 32 passes over the sealing ring embedded in the lower sealing connecting sleeve 310, and the high-pressure liquid stored in the rubber sleeve 39 can flow out from the outlet 3b, thus completing the release of the isolation.

[0040] For a detailed implementation of this embodiment, please refer to the second embodiment.

[0041] A second embodiment of the present invention discloses a method for replacing the wellhead main gate, such as... Figure 6 As shown, by lowering the wellhead temporary sealing device in the first embodiment into the well to isolate the pressure inside the well, the main gate of the wellhead can be replaced, as detailed below: S1, Equipment lowered into the well The continuous tubing is fixedly connected to the first upper connector 11, and then the wellhead temporary closing device is slowly lowered into the well to the predetermined position through the wellhead main gate.

[0042] S2, Anchoring Separation The cement pump truck continuously injects high-pressure liquid into the wellhead temporary closure device through coiled tubing for positive pressurization. Due to the presence of a setting ball seat 4, positive pressurization is achieved in the tool string. Here, the release and retrieval mechanism 1, the anchoring mechanism 2, and the packer expansion mechanism are defined as the tool string. First, the pressure in the tool string is pressurized to 15MPa. At this time, the pressure will shear the pin located between the piston 25 and the upper central tube 22 in the anchoring mechanism 2, causing the anchoring mechanism 2 to start anchoring. At the same time, the rubber sleeve 39 in the packer expansion mechanism also begins to expand. Subsequently, the pressure in the tool string is continuously pressurized to 25MPa. At this time, the slip 210 in the anchoring mechanism 2 completes the opening action, and the rubber sleeve 39 in the packer expansion mechanism 3 completes the expansion action.

[0043] S3, Anchoring Verification By applying a 4t lifting force to the coiled tubing, observe whether the wellhead temporary sealing device moves. If it does not move, it means that the wellhead temporary sealing device has been anchored and the subsequent steps can be carried out. If the wellhead temporary sealing device moves, it is necessary to unanchor and unseal the wellhead temporary sealing device, and then remove the wellhead temporary sealing device from the wellhead for repair before going down into the well again to perform step S2 anchoring and sealing.

[0044] S4, Device depressurization Pressurization to 30 MPa is continued through the coiled tubing into the wellhead temporary shut-off device, knocking the setting ball out of the setting ball seat 4, allowing the pressure in the tool string to be released through the setting ball seat 4 and the one-way valve 5.

[0045] S5, Drop By applying a downward pressure of 3t to the coiled tubing and then lifting the coiled tubing, the release and retrieval tool can be retrieved, and the fish-dropping tool string can be released. The release and retrieval tool includes a first upper connector 11, a first central tube 12, a release and retrieval assembly, and a sealing sleeve 110. The fish-dropping tool string includes a first lower connector 111, an anchoring mechanism 2, an expansion sealing mechanism 3, a setting ball seat 4, and a one-way valve 5.

[0046] S6, Separation Verification Open the casing gate and observe the overflow. If there is an overflow indication, it means that the seal is not complete. The wellhead temporary sealing device component located in the well needs to be retrieved, and the wellhead temporary sealing device should be taken out of the wellhead for repair before being put back into the well to start the work from step S2 anchoring and sealing. Conversely, if there is no overflow indication, it means that the seal is complete and subsequent work can be carried out.

[0047] S7. Replace the main gate. After the isolation is completed, the pressure inside the well will be confined within the well and will not affect the wellhead. At this point, the damaged wellhead main gate can be replaced.

[0048] S8, Removal device The hand-drop retrieval tool is lowered through the coiled tubing. When it reaches the top of the fish-dropping tool string, the top of the fish in the string is flushed. Then, the hand-drop retrieval tool is lowered to connect with the fish-dropping tool string, and a force of no more than 1t is applied to make the elastic claw 18 in the hand-drop retrieval tool and the first lower connector 111 in the fish-dropping tool string snap together. After the connection is completed, the anchoring mechanism 2 and the expansion packer mechanism 3 are unanchored and unsealed, and the coiled tubing can be lifted to remove the wellhead temporary closure device.

[0049] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wellhead temporary closure device, characterized in that: It includes a drop-off and retrieval mechanism, an anchoring mechanism, an expansion packer mechanism, a setting ball seat, and a check valve. The drop-off and retrieval mechanism, the anchoring mechanism, the expansion packer mechanism, the setting ball seat, and the check valve are connected end to end to form a columnar tool string that can pass through the main gate of the failed wellhead. The drop-and-retrieve mechanism includes a first central tube, a first upper connector, a sealing sleeve, a drop-and-retrieve component, and a first lower connector; wherein the first upper connector and the sealing sleeve are respectively fixedly sleeved at both ends of the first central tube, the drop-and-retrieve component is movably sleeved in the middle of the first central tube, and the first lower connector is movably sleeved on the sealing sleeve and detachably connected to the drop-and-retrieve component. The anchoring mechanism includes an upper central tube, a lower central tube, a second upper connector, a slip assembly, a clamping assembly, a releasing assembly, and a second lower connector; wherein the outer diameter of the lower central tube is the same as the inner diameter of the upper central tube, and the lower central tube is fixedly inserted through one end of the upper central tube, the second upper connector is fixedly sleeved on the other end of the upper central tube, and the second upper connector is fixedly connected to the first lower connector. The clamping assembly is fixedly sleeved on the upper central tube, the loosening assembly is movably sleeved on the lower central tube, and the slip assembly is fixedly sleeved on the lower central tube. Both ends of the slip assembly are fixedly connected to the movable ends of the clamping assembly and the loosening assembly, respectively. The second lower connector is fixedly inserted through the end of the loosening assembly away from the slip assembly. The expansion packer mechanism includes a second central tube, a third upper connector, a packer assembly, and a third lower connector; wherein the third upper connector is fixedly sleeved on one end of the second central tube and is fixedly connected to the second lower connector, the third lower connector is fixedly sleeved on the other end of the second central tube, and the packer assembly is sleeved on the middle of the second central tube. The inlet end of the setting ball seat is fixedly connected to the third lower connector, and the outlet end of the setting ball seat is fixedly connected to the inlet end of the check valve.

2. The wellhead temporary closure device according to claim 1, characterized in that: The drop-and-retrieve assembly includes a one-way locking ring, a first connecting sleeve, an elastic claw, a compression spring, and a slider; A one-way locking ring is installed on the first central tube, and the one-way locking ring can only move in the direction closer to the first upper connector. The first connecting sleeve is fixedly sleeved on the first central tube through a connector. The elastic claw and the compression spring are both movably sleeved on the first central tube, and the two ends of the compression spring are fixedly connected to the first connecting sleeve and the elastic claw, respectively. The slider is sleeved on the first central tube and fixedly connected to the claw end of the elastic claw. The first connecting sleeve is positioned on the side of the one-way locking ring away from the first upper connector. The first connecting sleeve covers the end of the compression spring and the elastic claw connected to the compression spring between the first connecting sleeve and the first central tube.

3. A wellhead temporary closure device according to claim 2, characterized in that: The clamping assembly includes a sealing limiting sleeve, a piston, a locking ring, and a high-pressure fluid communication hole; the sealing limiting sleeve is fixedly sleeved on the upper central tube, the piston is movably sleeved on the upper central tube, and the piston is located within the space enclosed by the sealing limiting sleeve and the upper central tube; the locking ring is sleeved on the piston, and the outer wall of the locking ring is fixedly connected to the sealing limiting sleeve; the high-pressure fluid communication hole is opened on the upper central tube, and the high-pressure fluid communication hole faces the space enclosed by the second upper connector, the sealing limiting sleeve, and the piston; The loosening assembly includes a limiting connecting sleeve, a return spring, a release ball seat, and a locking tooth block. The limiting connecting sleeve, return spring, and release ball seat are all movably sleeved on the lower central tube. The return spring and release ball seat are located in the space between the limiting connecting sleeve and the lower central tube. The two ends of the return spring are fixedly connected to the lower central tube and the limiting connecting sleeve, respectively, and the return spring is in a compressed state. The locking tooth block is movably sleeved on the lower central tube and fixedly connected to the release ball seat. The locking tooth block is unidirectionally locked in the direction close to the lower connecting tube. The slip assembly includes an upper connecting block, a lower connecting block, and a slip. The upper and lower connecting blocks are movably sleeved on the lower central tube, and the slip is fixedly sleeved on the lower central tube. The two movable ends of the slip are fixedly connected to the upper and lower connecting blocks, respectively. The other end of the upper connecting block is fixedly connected to the piston, and the other end of the lower connecting block is fixedly connected to the limiting connecting sleeve.

4. A wellhead temporary closure device according to claim 3, characterized in that: The sealing and limiting sleeve includes an upper outer cylinder and a connecting sleeve. The two ends of the upper outer cylinder are fixedly connected to the second upper connector and one end of the connecting sleeve, respectively. The other end of the connecting sleeve is fixedly connected to the locking ring. The limiting connecting sleeve includes an inner outer cylinder and a lower outer cylinder. The two ends of the inner outer cylinder are fixedly connected to the lower connecting block and one end of the lower outer cylinder, respectively. The other end of the lower outer cylinder is fixedly connected to the second lower connector. The reset spring is located in the space between the inner outer cylinder and the lower central tube. The unsealing ball seat is located in the space between the lower outer cylinder and the lower central tube. The length of the lower outer cylinder is greater than the length of the unsealing ball seat.

5. A wellhead temporary closure device according to any one of claims 1-4, characterized in that: The packing assembly includes a control sleeve, valve seat, check piston, upper sealing connecting sleeve, limit spring, lower sealing connecting sleeve, rubber sleeve, inlet and outlet; The control sleeve is movably fitted onto the second central tube and fixedly connected to the third upper head via a connector. The valve seat is fixedly fitted onto the second central tube. The check piston passes through the end of the valve seat away from the third upper connector. The upper sealing connecting sleeve and the lower sealing connecting sleeve are fixedly fitted onto the second central tube, with the upper sealing connecting sleeve enclosing the valve seat and the check piston within it. The limiting spring is also encased in the upper sealing connecting sleeve, and the two ends of the limiting spring are fixedly connected to the check piston and the upper sealing connecting sleeve respectively. The rubber tube is fixedly sleeved on the second central tube, and the two ends of the rubber tube are fixedly connected to the upper sealing connecting sleeve and the lower sealing connecting sleeve respectively. The liquid inlet and liquid outlet are both opened on the second central tube for filling and discharging the rubber tube.

6. A method for replacing the main gate valve at the wellhead, characterized in that: This method, based on the wellhead temporary shut-off device of claim 1, specifically includes the following steps: S1. Lowering the device into the well: Lower the temporary well-closing device to the designated position inside the well; S2, Anchoring and Separation: Activate the anchoring and sealing mechanisms to complete the anchoring of the wellhead temporary closure device at the wellhead and the sealing of the wellhead; S3. Anchoring verification: Raise the wellhead temporary closure device to verify whether the anchoring is successful. If successful, proceed to the next step; otherwise, re-anchor. S4. Device depressurization: Continue to pressurize the device until the set ball seat is knocked off, thus completing the depressurization process; S5, Release: Press down the release retrieval component to release the anchoring mechanism, expansion sealing mechanism, setting ball seat and check valve; S6. Packer verification: Verify whether the packer is completely sealed by opening the casing gate and observing the overflow. If it is completely sealed, proceed to the next step. If it is not completely sealed, remove the device and put it back into the well. S7. Replace the main gate: Replace the faulty main gate at the wellhead; S8. Retrieval Device: Unanchor and depressurize the anchoring mechanism and expansion packer mechanism, and retrieve the wellhead temporary closure device using the drop-out retrieval assembly.

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