A plugging tool for wellhead Christmas tree pressure exchange valve without releasing

Abstract

The application relates to the technical field of gas tree valve replacement maintenance, and discloses a plugging tool for wellhead gas tree pressure-bearing valve replacement without releasing the tool, which comprises a coaxially arranged shell, a limiting sleeve, a second cylinder, a rubber cylinder assembly, a guide shoe, a mandrel, a spring, a first cylinder and a piston. When the valve replacement operation of the gas tree is performed, the plugging tool can be sent into the front-end pipeline of the valve by connecting a feeding and pressurizing device on the shell. In use, the rubber cylinder assembly can be axially compressed and radially expanded by hydraulic pressure, so that the rubber cylinder assembly is tightly sealed with the inner wall of the pipeline. When the pressurizing is stopped and the feeding and pressurizing device is subsequently disassembled, the spring and the rubber cylinder assembly can play a pressure maintaining effect under the action of the spring and the elastic force of the rubber cylinder assembly, so that the reliability of the sealing and plugging is maintained. After the valve replacement is completed, the mandrel can be directly pushed by a rigid member to realize pressure relief and unsealing. The plugging tool can realize pressure-bearing valve replacement operation, has the advantages of reliable sealing, easy unsealing, and relatively simple structure and convenient operation.

Description

Technical Field

[0001] This invention relates to the field of wellhead gas production tree valve replacement and maintenance technology, specifically a plugging tool for replacing valves on pressure without losing control of the wellhead gas production tree. Background Technology

[0002] The gas production tree refers to the general term for the part installed above the pipe head of the wellhead device. It mainly consists of the wellhead four-way valve and main control valves (main gate valve, pipeline gate valve, needle valve, pressure measuring gate valve, casing gate valve, etc.). It is the main device for opening and closing the well, regulating pressure, lowering the pressure gauge to measure pressure, and measuring the wellhead pressure.

[0003] Because the wellhead equipment directly controls the extraction of natural gas from the well under high pressure, it is operational immediately after installation, making the maintenance and replacement of the main control valve extremely difficult. The traditional replacement method involves first using kill fluid to kill the well during construction, and only after the kill is stable can the main control valve be replaced. This method suffers from problems such as long construction periods, numerous equipment and labor requirements, multiple cooperating construction units, large number of personnel, serious environmental pollution from the discharge of kill fluid, and high construction costs. Furthermore, this traditional method can cause secondary damage to the formation at the bottom of the well, especially in older wells in the later stages of production. Due to lower formation energy, it is difficult to restore production to its original level after kill fluid treatment, and some wells may even be permanently shut down and become abandoned wells.

[0004] To overcome the shortcomings of traditional replacement methods, those skilled in the art have been dedicated to researching replacement methods for valves under pressure. Currently, we use a slip positioning method for valve replacement or repair. This method involves installing slips at a fixed point on the inner wall of the pipe head at the front end of the valve to be replaced to seal it, disconnecting the valve to be replaced from the gas tree pipeline for easy replacement. However, in practical applications, due to long-term corrosion of the pipe head channel by acidic media, its inner wall is often uneven, making it difficult to select the appropriate positioning point. After installation, the connection and sealing reliability between the slips and the inner wall are poor, posing safety hazards during subsequent valve replacement operations. Furthermore, disassembling and removing the slips after valve replacement is also quite difficult. Existing technologies also have various forms of pipe head plugging devices in other fields, but these devices are difficult to simultaneously meet the requirements of reliable sealing, easy unsealing, and convenient operation when used for valve replacement under pressure in gas trees. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a plugging tool for replacing valves under pressure without losing control of the wellhead gas production tree. When used for replacing gas production tree valves, it does not require well control operations and can achieve valve replacement under pressure. It has the advantages of reliable sealing and easy unsealing, and its structure is relatively simple and easy to operate.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A plugging tool for a pressure-replacing valve on a wellhead gas production tree that can be easily removed includes a housing, a limiting sleeve, a second cylinder, a rubber sleeve assembly, a guide shoe, a mandrel, a spring, a first cylinder, and a piston, all arranged coaxially.

[0008] The housing is a hollow cylindrical structure with openings at both ends. The limiting sleeve is fixedly inserted into the middle of the housing. One end of the second cylinder is slidably disposed inside one end of the housing. The other end of the second cylinder is fixedly connected to the guide shoe. The rubber sleeve assembly is sleeved outside the second cylinder. The two ends of the rubber sleeve assembly abut against the end of the housing and the end of the guide shoe, respectively.

[0009] The limiting sleeve has a first core hole and a first pressure transmission hole at the end away from the guide shoe. The limiting sleeve has a small diameter hole and a large diameter hole sequentially processed along the axis to the other end. The two ends of the first pressure transmission hole are respectively connected to the small diameter hole and the inner cavity of the housing at the end away from the second cylinder. The connection between the small diameter hole and the large diameter hole forms a conical sealing platform.

[0010] One end of the first cylinder is fixedly inserted into the end of the large-diameter hole away from the small-diameter hole and is machined with a second core hole and a second pressure transmission hole. The other end of the first cylinder is fixedly connected to the piston. The two ends of the second pressure transmission hole are respectively connected to the large-diameter hole and the inner cavity of the first cylinder.

[0011] The outer wall of the first cylinder is slidably adapted to the end of the second cylinder away from the guide shoe. The piston is slidably adapted to the inner wall of the second cylinder. The piston divides the inner cavity of the second cylinder into a rod cavity and a rodless cavity. The rod cavity is located on the side of the piston close to the first cylinder. A third pressure transmission hole is provided on the side wall of the first cylinder. The two ends of the third pressure transmission hole are respectively connected to the rod cavity and the inner cavity of the first cylinder. A flow channel hole is provided on the guide shoe. The two ends of the flow channel hole are respectively connected to the rodless cavity and the side of the guide shoe away from the second cylinder.

[0012] A tapered block is fixedly sleeved on the mandrel. One end of the mandrel is slidably disposed in the first core hole, and the other end of the mandrel is slidably disposed in the second core hole. The tapered block is disposed in the large-diameter hole and is adapted to the tapered sealing platform.

[0013] The spring is sleeved on the mandrel, and the two ends of the spring abut against the ends of the conical block and the first cylinder, respectively.

[0014] Specifically, the rubber tube assembly includes a plurality of rubber tubes, which are sequentially sleeved on the outside of the second cylinder, and a spacer ring is provided between each two adjacent rubber tubes.

[0015] Specifically, sealing rings are provided between the mandrel and the first core hole, between the mandrel and the second core hole, between the outer wall of the first cylinder and the end of the second cylinder away from the guide shoe, and between the piston and the inner wall of the second cylinder.

[0016] Specifically, the end of the housing away from the shoe is machined with internal thread.

[0017] The beneficial effects of this invention are:

[0018] The wellhead gas production tree non-discardable pressure-changing valve plugging tool includes a coaxially arranged housing, limiting sleeve, second cylinder, rubber sleeve assembly, guide shoe, mandrel, spring, first cylinder, and piston. The limiting sleeve is fixedly inserted into the middle of the housing. One end of the second cylinder is slidably installed inside one end of the housing, and the other end of the second cylinder is fixedly connected to the guide shoe. The rubber sleeve assembly is sleeved on the outside of the second cylinder, and its two ends abut against the ends of the housing and the end of the guide shoe, respectively. One end of the first cylinder is fixedly inserted into one end of the limiting sleeve, and the cylinder body of the first cylinder slides through one end of the second cylinder. The other end of the first cylinder is fixedly connected to the piston, which slides inside the second cylinder. The mandrel slides inside the limiting sleeve and has a conical block sleeved on it. The limiting sleeve has a conical limiting platform, and the spring provides elastic force to press the conical block against the conical sealing platform. The limiting sleeve has a first pressure transmission hole, and the first cylinder has a second and a third pressure transmission hole. When pressurizing the wellhead gas production tree, the hydraulic oil enters through the first pressure transmission hole and pushes open the conical block. It then sequentially passes through the second pressure transmission hole, the inner cavity of the first cylinder, and the third pressure transmission hole into the rod chamber of the second cylinder. This drives the second cylinder and the guide shoe to move axially, causing the rubber sleeve assembly to compress axially and expand radially until the rubber sleeve assembly and the inner wall of the pipeline are tightly sealed. When pressurization stops, the spring and the elastic force of the rubber sleeve assembly maintain pressure and ensure reliable sealing. After valve replacement, the rigid components can be used to push the mandrel to release pressure and unseal the seal.

[0019] Overall, this wellhead gas production tree can be plugged with a non-discarding pressure valve replacement tool, enabling pressure valve replacement operations. It has the advantages of reliable sealing and easy unsealing, and its structure is relatively simple and easy to use. Attached Figure Description

[0020] Figure 1 This is a cross-sectional schematic diagram of a plugging tool for a wellhead gas production tree that allows for pressure-controlled valve replacement without loss, according to the present invention.

[0021] Figure 2 for Figure 1 Enlarged view of section A in the middle;

[0022] In the figure, 1-shell, 2-limiting sleeve, 3-spindle, 4-first cylinder, 5-second cylinder, 6-piston, 7-lead shoe, 8-rubber sleeve, 9-spacer ring, 10-first pressure transmission hole, 11-small diameter hole, 12-large diameter hole, 13-second pressure transmission hole, 14-third pressure transmission hole, 15-flow channel hole, 16-conical block, 17-spring. Detailed Implementation

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0024] like Figure 1 , Figure 2 As shown, a plugging tool for a wellhead gas production tree with a pressure-replacing valve that can be easily replaced without being lost includes a housing 1, a limiting sleeve 2, a second cylinder 5, a rubber sleeve assembly, a guide shoe 7, a spindle 3, a spring 17, a first cylinder 4, and a piston 6, all arranged coaxially.

[0025] The housing 1 is a hollow cylindrical structure with openings at both ends. The limiting sleeve 2 is fixedly inserted into the middle of the housing 1. One end of the second cylinder 5 is slidably disposed inside one end of the housing 1. The other end of the second cylinder 5 is fixedly connected to the guide shoe 7. The rubber sleeve assembly is sleeved outside the second cylinder 5. The two ends of the rubber sleeve assembly abut against the end of the housing 1 and the end of the guide shoe 7, respectively. When the second cylinder 5 slides towards the limiting sleeve 2, it can drive the guide shoe 7 to slide axially, thereby causing the rubber sleeve assembly to be axially compressed and radially expanded.

[0026] The limiting sleeve 2 is a hollow cylindrical structure with one end open. The end of the limiting sleeve 2 away from the guide shoe 7 is a closed end, where a first core hole and a first pressure transmission hole 10 are machined. A small diameter hole 11 and a large diameter hole 12 are machined sequentially along the axis to the other end of the limiting sleeve 2 to form a hollow structure. An opening is formed at the other end of the large diameter hole 12. The connection between the small diameter hole 11 and the large diameter hole 12 is machined to form a conical sealing platform. The two ends of the aforementioned first pressure transmission hole 10 are respectively connected to the small diameter hole 11 and the inner cavity of the housing 1 away from the second cylinder 5.

[0027] The first cylinder 4 has a cylindrical structure with one closed end. This closed end is fixedly inserted into the end of the large-diameter hole 12 away from the small-diameter hole 11, and a second core hole and a second pressure transmission hole 13 are machined at this end. The other end of the first cylinder 4 is fixedly connected to the piston 6. The two ends of the second pressure transmission hole 13 are respectively connected to the large-diameter hole 12 and the inner cavity of the first cylinder 4. The outer wall of the first cylinder 4 is slidably adapted to the end of the second cylinder 5 away from the guide shoe 7. The piston 6 is slidably adapted to the inner wall of the second cylinder 5. The piston 6 divides the inner cavity of the second cylinder 5 into a rod cavity and a rodless cavity. The rod cavity is located on the side of the piston 6 close to the first cylinder 4. A third pressure transmission hole 14 is opened on the side wall of the first cylinder 5. The two ends of the third pressure transmission hole 14 are respectively connected to the rod cavity and the inner cavity of the first cylinder 4. A flow channel hole 15 is opened on the guide shoe 7. The two ends of the flow channel hole 15 are respectively connected to the rodless cavity and the side of the guide shoe 7 away from the second cylinder 5.

[0028] A conical block 16 is fixedly sleeved on the mandrel 3. One end of the mandrel 3 is slidably disposed in the aforementioned first core hole, and the other end of the mandrel 3 is slidably disposed in the aforementioned second core hole. The conical block 16 is disposed in the large-diameter hole 12 and is adapted to the aforementioned conical sealing platform. A spring 17 is sleeved on the mandrel 3, and both ends of the spring 17 abut against the ends of the conical block 16 and the first cylinder 4, respectively.

[0029] The wellhead gas production tree, without losing the pressure-changing valve, uses a plugging tool in the initial state, as follows: Figure 1 As shown, it is used in this way;

[0030] First, connect the feeding and pressurizing device to the end of the housing 1 away from the guide shoe 7. Then, send the plugging tool into the appropriate position in the pipeline at the front end of the valve to be replaced. It should be understood that in order to ensure that the plugging tool is inserted into place, the overall diameter of the plugging tool and the diameter of the feeding and pressurizing device, at least the front section diameter, are smaller than the through diameter of the valve to be replaced when it is open. The plugging tool can be sent directly through the valve (when the valve is open) into the pipeline at its front end.

[0031] Subsequently, a pressurization operation is performed. This pressurization operation refers to pumping hydraulic oil (or other media) into the housing 1 from the end away from the guide shoe 7 through the feeding and pressurizing device. During the pressurization process, the hydraulic oil enters the small diameter hole 11 through the first pressure transmission hole 10. The pressure in the small diameter hole 11 increases, and this pressure acts on the conical block 16, causing the spindle 3 to move axially as a whole and compressing the spring 17. At this time, the conical block 16 separates from the conical sealing platform and a gap is generated. The hydraulic oil flows into the large diameter hole 12 from this gap. Then, the hydraulic oil flows into the rod chamber of the second cylinder 5 through the second pressure transmission hole 13, the inner cavity of the first cylinder 4, and the third pressure transmission hole 14 in sequence. During this process, the air and other media in the rodless chamber of the second cylinder 5 will be discharged from the flow channel hole 15 without obstruction. As the amount of hydraulic oil in the rod chamber increases, it can drive the second cylinder 5 and the guide shoe 7 to move axially as a whole, so that the rubber sleeve assembly is axially compressed and radially expanded until the outer wall of the rubber sleeve assembly and the inner wall of the pipeline are tightly expanded, thus completing the sealing of the pipeline at the front end of the valve to be replaced. Because this plugging tool achieves sealing through the expansion of a rubber sleeve assembly, it is less affected by unevenness in the inner wall of the pipe during use, and can effectively solve the problem of difficulty in selecting the blocking point.

[0032] The expanded plugging tool is then left inside the pipeline for sealing. The feed and pressurization device can be disassembled and removed, after which the valve can be replaced. Pressurization is stopped before disassembling the feed and pressurization device. At this time, the spring 17 rebounds, pressing the conical block 16 against the conical sealing platform to form a seal. Simultaneously, the elasticity of the rubber sleeve assembly also creates an inward tendency force. This tendency force causes the second cylinder 5 and the guide shoe 7 to move axially in the opposite direction, thereby compressing the rod chamber of the second cylinder 5. The hydraulic oil in the rod chamber flows sequentially through the third pressure transmission hole 14, the inner cavity of the first cylinder 4, and the second pressure transmission hole 13 into the large-diameter hole 12, further acting on the conical block 16 to maintain the reliability of the seal. Therefore, when pressurization is stopped and the feed and pressurization device is subsequently removed, the plugging tool automatically maintains pressure, effectively ensuring the reliability of the pipeline sealing.

[0033] After the valve is replaced, the blocking tool needs to be removed. When removing it, the removal tool (e.g., a removal sleeve with a diameter smaller than the valve's through diameter) can be connected again to the end of the housing 1 away from the guide shoe 7. The mandrel 3 is axially pushed towards the guide shoe 7 by a rigid member (e.g., a movable rod that passes through the removal sleeve), so that the conical block 16 is separated from the conical sealing platform to complete the pressure relief. Under the action of the aforementioned tendency force, the rubber sleeve assembly retracts, thereby quickly achieving unsealing. Afterwards, the blocking tool can be removed as a whole by moving the removal tool outward.

[0034] As can be seen from the above operation process, the plugging tool for replacing valves on the wellhead gas production tree without losing control can replace valves on pressure without well control operation. It has the advantages of reliable sealing and easy unsealing, and its structure is relatively simple and easy to use.

[0035] In practice:

[0036] The rubber sleeve assembly can use a single rubber sleeve 8. However, if the axial dimension of a single rubber sleeve 8 is too large (the height-to-diameter ratio is too large), its expansion and deformation will be uncontrollable, making it difficult to ensure the sealing effect. Therefore, the rubber sleeve assembly includes several rubber sleeves 8, which are sequentially sleeved outside the second cylinder 5. A spacer ring 9 is provided between two adjacent rubber sleeves 8.

[0037] Sealing rings are provided between the mandrel 3 and the first core hole, between the mandrel 3 and the second core hole, between the outer wall of the first cylinder 4 and the end of the second cylinder 5 away from the guide shoe 7, and between the piston 6 and the inner wall of the second cylinder 5 to ensure sealing and pressure transmission effect.

[0038] The end of the housing 1 away from the guide shoe 7 is machined with an internal thread to facilitate connection or disconnection with the aforementioned feeding and pressurizing device, removal tool and blocking tool.

[0039] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A plugging tool for pressure-controlled valve replacement at a wellhead gas production tree without loss of control, characterized in that, It includes a housing, a limiting sleeve, a second cylinder, a rubber sleeve assembly, a guide shoe, a spindle, a spring, a first cylinder, and a piston, all arranged coaxially. The housing is a hollow cylindrical structure with openings at both ends. The limiting sleeve is fixedly inserted into the middle of the housing. One end of the second cylinder is slidably disposed inside one end of the housing. The other end of the second cylinder is fixedly connected to the guide shoe. The rubber sleeve assembly is sleeved outside the second cylinder. The two ends of the rubber sleeve assembly abut against the end of the housing and the end of the guide shoe, respectively. The limiting sleeve has a first core hole and a first pressure transmission hole at the end away from the guide shoe. The limiting sleeve has a small diameter hole and a large diameter hole sequentially processed along the axis to the other end. The two ends of the first pressure transmission hole are respectively connected to the small diameter hole and the inner cavity of the housing at the end away from the second cylinder. The connection between the small diameter hole and the large diameter hole forms a conical sealing platform. One end of the first cylinder is fixedly inserted into the end of the large-diameter hole away from the small-diameter hole and is machined with a second core hole and a second pressure transmission hole. The other end of the first cylinder is fixedly connected to the piston. The two ends of the second pressure transmission hole are respectively connected to the large-diameter hole and the inner cavity of the first cylinder. The outer wall of the first cylinder is slidably adapted to the end of the second cylinder away from the guide shoe. The piston is slidably adapted to the inner wall of the second cylinder. The piston divides the inner cavity of the second cylinder into a rod cavity and a rodless cavity. The rod cavity is located on the side of the piston close to the first cylinder. A third pressure transmission hole is provided on the side wall of the first cylinder. The two ends of the third pressure transmission hole are respectively connected to the rod cavity and the inner cavity of the first cylinder. A flow channel hole is provided on the guide shoe. The two ends of the flow channel hole are respectively connected to the rodless cavity and the side of the guide shoe away from the second cylinder. A tapered block is fixedly sleeved on the mandrel. One end of the mandrel is slidably disposed in the first core hole, and the other end of the mandrel is slidably disposed in the second core hole. The tapered block is disposed in the large-diameter hole and is adapted to the tapered sealing platform. The spring is sleeved on the mandrel, and the two ends of the spring abut against the ends of the conical block and the first cylinder, respectively.

2. The plugging tool for pressure-controlled valve replacement at the wellhead gas production tree according to claim 1, characterized in that, The rubber tube assembly includes several rubber tubes, which are sequentially sleeved on the outside of the second cylinder, with a spacer ring between each two adjacent rubber tubes.

3. The plugging tool for pressure-controlled valve replacement at the wellhead gas production tree according to claim 1, characterized in that, A sealing ring is provided between the mandrel and the first mandrel hole, between the mandrel and the second mandrel hole, between the outer wall of the first cylinder and the end of the second cylinder away from the guide shoe, and between the piston and the inner wall of the second cylinder.

4. The plugging tool for pressure-controlled valve replacement at the wellhead gas production tree according to claim 1, characterized in that, The end of the shell furthest from the shoe is machined with internal threads.

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