Hydraulic locking structure for preventing hanger from moving upwards

Abstract

The invention discloses a hydraulic locking structure for preventing a hanger from moving upwards, and relates to the technical field of petroleum drilling and production equipment, the hydraulic locking structure comprises a tubing head body, a locking assembly and the hanger, the tubing head body is provided with a main drift diameter ring groove, a through round hole is formed behind the main drift diameter ring groove, and the locking assembly comprises an inner sleeve, an outer sleeve, a locking rod and a limiting pressing block. The inner sleeve and the outer sleeve are inserted into the two ends of the through circular hole; the limiting pressing block is installed in the main drift diameter ring groove, the locking rod is fixedly connected with the limiting pressing block, and the limiting pressing block and the hanger are locked in a conical surface fit mode. A hydraulic system is further arranged and comprises a first hydraulic channel, a second hydraulic channel and a piston, two sealing cavities are formed between the piston and the locking assembly in the through round hole, the sealing cavities are connected with the two hydraulic channels, and the pressure difference of the two sealing cavities is controlled to control stretching and retreating of the limiting pressing block. The problem that in the prior art, a high-pressure underground hanger moves upwards, so that a jackscrew deforms and cannot be detached is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling and production equipment, and more specifically to a hydraulic locking structure for preventing the hanger from moving upward. Background Art

[0002] During the drilling process, in order to prevent the wear-resistant sleeve from rotating with the drill string and wearing the sealing surface, multiple setscrews are usually arranged around the upper flange of the casing head and tubing head to fix the wear-resistant sleeve. However, in fact, in addition to when using the wear-resistant sleeve, the setscrews are also habitually tightened after installing the casing hanger and tubing hanger on site, which can assist in preventing the hanger from moving upward under the condition of relatively low well pressure. With the exploration and development of deep wells and ultra-deep wells, the well pressure of key wells is getting higher and higher at present. There have been multiple problems on site where the hanger moves upward, resulting in the deformation of the setscrews and being unable to be disassembled. If it is necessary to deal with the deformed setscrews on site, only the upper blowout preventer group can be completely disassembled, which not only increases the well control risk but also delays the drilling cycle. Based on the design of the traditional setscrew device being unable to prevent the hanger from moving upward in high-pressure wells, there is an urgent need to develop a locking structure that can effectively prevent the hanger from moving upward to avoid the above situation from occurring again. Summary of the Invention

[0003] In order to overcome the defects existing in the above-mentioned prior art, the present invention discloses a hydraulic locking structure for preventing the hanger from moving upward. The purpose of the present invention is to solve the problem that the hanger moves upward in a high-pressure well in the prior art, resulting in the deformation of the setscrews and being unable to be disassembled.

[0004] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows: A hydraulic locking structure for preventing the hanger from moving upward, including a tubing head body, a locking assembly, and a hanger. A main through-hole ring groove is provided on the tubing head body, and a through-round hole for assembling the locking assembly is provided on the inner side behind the main through-hole ring groove. The locking assembly mainly includes an inner sleeve, an outer sleeve, a locking rod, and a limit pressing block. The inner sleeve and the outer sleeve are inserted into the through-round hole and fixed; the limit pressing block is installed in the main through-hole ring groove, the locking rod passes through the inner sleeve and the outer sleeve and is threadedly connected to the limit pressing block, the locking rod drives the limit pressing block to extend out, and the front end surface of the limit pressing block is in tapered surface fit and locking with the metal seal of the hanger; A hydraulic system is also provided. The hydraulic system includes a first hydraulic passage, a second hydraulic passage, and a piston. The piston is assembled in the middle section of the locking rod and is located between the inner sleeve and the outer sleeve. The piston forms two left and right sealing cavities between the through-round hole and the locking assembly. The left sealing cavity is connected to the first hydraulic passage, and the right sealing cavity is connected to the second hydraulic passage. By controlling the pressure difference between the two sealing cavities, the movement of the piston is controlled, thereby driving the locking rod to move left and right, achieving the effect of making the limit pressing block extend out and retract.

[0005] Preferably, the first hydraulic passage includes a first branch I, a second branch I, a locking check valve, and a locking plug. The first branch I penetrates from the upper end face of the tubing head body to the left sealing cavity, and the locking plug is arranged at the upper end face outlet. The second branch I penetrates from the outer circumference direction of the tubing head body to the confluence at the first branch I passage, and the locking check valve is arranged at the outer circumference outlet. The second hydraulic passage includes a first branch II, a second branch II, an unlocking check valve, and an unlocking plug. The first branch II penetrates from the lower end face of the tubing head body to the right sealing cavity, and the unlocking plug is arranged at the lower end face outlet. The second branch II penetrates from the outer circumference direction of the tubing head body to the confluence at the first branch II passage, and the unlocking check valve is arranged at the outer circumference outlet.

[0006] Preferably, a sealing ring is provided on the piston.

[0007] Preferably, the locking check valve and the unlocking check valve adopt electric check valves.

[0008] Preferably, sealing rings are provided on the outer circumference and inner hole of the outer sleeve, and sealing rings are also provided on the outer circumference and inner hole of the inner sleeve.

[0009] Preferably, when the front end of the limit pressing block is pushed out of the main diameter ring groove by the locking rod, there is a space for the limit pressing block to retreat between the rear end face of the limit pressing block and the inner side wall in the main diameter ring groove.

[0010] Preferably, when the limit pressing block is locked in cooperation with the conical surface of the metal seal, the space for the limit pressing block to retreat corresponds to the maximum distance that the piston moves to the left.

[0011] Preferably, multiple scale lines are provided on the outer circumference of the tail end of the locking rod, which can indicate the position of the locking rod.

[0012] Preferably, the tail end of the locking rod is designed as a square.

[0013] Preferably, the inner sleeve and the outer sleeve are fixed to the through round hole by screws.

[0014] The beneficial effects of the present invention: 1. Compared with the prior art, the hydraulic locking structure of the present invention has a main diameter annular groove on the tubing head body, and the main diameter annular groove is used to assemble the limit pressure block, so that the limit pressure block can move radially in the main diameter annular groove. When the front end of the limit pressure block is pushed out of the main diameter annular groove, the hanger can be locked. When the front end of the limit pressure block is located in the main diameter annular groove, the hanger is unlocked. The front end of the limit pressure block cooperates with the cone surface of the locking hanger. The cone surface cooperates to decompose the axial upward force of the hanger when it moves upward into part of the axial upward force and part of the radial force through the cone surface, thereby reducing the axial force of the limit pressure block. On the one hand, since the axial force of the limit pressure block is partially decomposed, the axial force is reduced, thereby preventing the limit pressure block from being axially squeezed and deformed; on the other hand, the matching structure of the main diameter annular groove and the limit pressure block further strengthens the axial force structure of the limit pressure block, thereby further preventing the limit pressure block from being axially squeezed and deformed. The locking structure of the present invention decomposes part of the upward force of the hanger through the conical surface at the front end of the limiting pressure block, which can effectively avoid the situation where the locking structure is deformed and causes difficulty in disassembly.

[0015] 2. In the present application, a hydraulic system is used to realize the locking and unlocking operations of the locking structure. By setting different pressure differences in the sealing chambers at both ends of the piston, the effect of controlling the left and right movement of the piston is achieved, driving the locking rod, thereby achieving the technical effect of controlling the extension and retraction of the limit pressure block into the main diameter ring groove. This implementation method is more convenient, more labor-saving, and more efficient than manually tightening with a wrench or other operating methods that require manual intervention. Compared with the problem of thread slippage that is prone to occur with threads, this method is not prone to failure and is more reliable.

[0016] 3. In the present application, a space for the limit pressure block to retreat is provided in the main diameter annular groove, so as to facilitate the unlocking of the hanger. The hanger can be unlocked without completely removing the locking structure, and the unlocking method is simpler.

[0017] 4. In this application, a sealing ring is provided inside the structure, which can meet the functional needs of the structural design and the requirements of the annular pressure test.

[0018] 5. The present application has a strong ability to resist high pressure in the well, but its structure is simple, easy to replace, and the components are not easily damaged. Even if damage occurs, each part can be replaced separately, which will not cause a major impact on the entire drilling process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the locking hanger of the present invention; Figure 2 This is a schematic diagram of the unlocking hanger of the present invention; Figure 3 It is a front view of the hydraulic locking structure of the present invention; Figure 4 Side view of the hydraulic locking structure of the present invention Figure 5 Schematic diagram of the installation of the traditional setscrew in the prior art Reference numerals 1. Tubing head body; 2. Locking check valve; 3. Locking assembly (3-1. Locking rod; 3-2. Sealing ring; 3-3. Piston; 3-4. Outer sleeve; 3-5. Sealing ring; 3-6. Sealing ring; 3-7. Inner sleeve; 3-8. Sealing ring; 3-9. Sealing ring; 3-10. Socket head cap screw; 3-11. Limit pressing block); 4. Unlocking check valve; 5. Locking plug; 6. Unlocking plug; 7. Hanger; 8. Upper flange Detailed implementation manners

[0020] The following will clearly and completely describe the concept, specific structure and technical effects generated by the present invention in combination with the embodiments and the drawings, so as to fully understand the purpose, features and effects of the present invention Detailed implementation manners The following will be described in conjunction with the drawings. As Figure 1 and Figure 2 shown, a hydraulic locking structure for preventing the hanger from moving upward includes a tubing head body 1, a locking assembly 3 and a hanger 7. A main diameter ring groove is provided on the tubing head body 1, and a through circular hole for assembling the above-mentioned locking assembly 3 is provided on the inner side behind the main diameter ring groove

[0022] Again, as Figure 3 and Figure 4 shown, the above-mentioned locking assembly 3 mainly includes an inner sleeve 3-7, an outer sleeve 3-4, a locking rod 3-1 and a limit pressing block 3-11. The above-mentioned inner sleeve 3-7 and outer sleeve 3-4 are inserted into the through circular hole and fixed. The above-mentioned limit pressing block 3-11 is installed in the main diameter ring groove and can move radially in the main diameter ring groove. The above-mentioned locking rod 3-1 passes through the above-mentioned inner sleeve 3-7 and outer sleeve 3-4 and is threadedly connected to the above-mentioned limit pressing block 3-11. The above-mentioned locking rod 3-1 drives the limit pressing block 3-11 to extend. The front end face of the limit pressing block 3-11 is in tapered surface fit and locking with the metal seal of the hanger 7. The locking rod 3-1 and the limit pressing block 3-11 are screwed together as a whole, so that the limit pressing block 3-11 can follow the forward and backward movement of the locking rod 3-1. The traditional setscrew uses a line-surface contact method for locking, and the contact area is smaller than that of the limit pressing block 3-11 in this application. When receiving the force of the upward movement of the hanger 7 brought by the high pressure in the well, it is easy to become unstable, and the bearing capacity is not as good as the tapered surface fit in this application. Moreover, the cross-section of the setscrew rod is small, and it is easy to deform or be cut when stressed. Setting the limit pressing block 3-11 can increase the stress area and bearing capacity of the locking rod 3-1

[0023] A main diameter ring groove is provided on the tubing head body 1. The main diameter ring groove is used to assemble the limit pressing block 3-11, so that the limit pressing block 3-11 can move radially in the main diameter ring groove. When the front end of the limit pressing block 3-11 is pushed out of the main diameter ring groove, it can cooperate with the conical surface of the metal seal of the hanger 7 to achieve the function of locking the hanger 7. When the front end of the limit pressing block 3-11 is located in the main diameter ring groove, the unlocking of the hanger 7 is realized. The front end of the limit pressing block 3-11 cooperates with the conical surface of the metal seal of the hanger 7. This conical surface cooperation can decompose the axial upward force when the hanger 7 moves upward into a part of the axial upward force and a part of the radial force through this conical surface, reducing the axial force on the limit pressing block 3-11. On the one hand, since part of the axial force on the limit pressing block 3-11 is decomposed, the axial force is reduced, avoiding the axial extrusion deformation of the limit pressing block 3-11; on the other hand, the matching structure of the main diameter ring groove and the limit pressing block 3-11 further enhances the axial force structure of the limit pressing block 3-11, further avoiding the axial extrusion deformation of the limit pressing block 3-11. The locking structure of the present invention decomposes part of the upward force of the hanger 7 through the conical surface at the front end of the limit pressing block 3-11, which can effectively avoid the situation that the locking structure is deformed and difficult to disassemble.

[0024] A hydraulic system is also provided. The hydraulic system includes a first hydraulic passage, a second hydraulic passage and a piston 3-3. The piston 3-3 is assembled in the middle section of the locking rod 3-1 and is located between the inner sleeve 3-7 and the outer sleeve 3-4. The piston 3-3 forms two left and right sealed cavities with the locking assembly 3 in the through-round hole. The left sealed cavity is connected to the first hydraulic passage, and the right sealed cavity is connected to the second hydraulic passage. The user can control the movement of the piston 3-3 by controlling the pressure difference between the two sealed cavities, thereby driving the locking rod 3-1 to move left and right, achieving the effect of making the limit pressing block 3-11 extend out of the main diameter ring groove and retract into the main diameter ring groove.

[0025] In this application, the first hydraulic passage includes a first branch I, a second branch I, a locking check valve 2 and a locking plug 5. The first branch I penetrates from the upper end face of the tubing head body to the left sealed cavity, and the locking plug 5 is arranged at the upper end face outlet. The second branch I penetrates from the outer circle direction of the tubing head body to the confluence of the first branch I passage, and the locking check valve 2 is arranged at the outer circle outlet; the second hydraulic passage includes a first branch II, a second branch II, an unlocking check valve 4 and an unlocking plug 6. The first branch II penetrates from the lower end face of the tubing head body to the right sealed cavity, and the unlocking plug 6 is arranged at the lower end face outlet. The second branch II penetrates from the outer circle direction of the tubing head body to the confluence of the first branch II passage, and the unlocking check valve 4 is arranged at the outer circle outlet.

[0026] The function of the hydraulic passage is to increase and decrease the pressure in the two sealing cavities, and also to maintain and release the pressure in the two sealing cavities. The present application is set to have two branches, which is an optimal solution proposed based on processing methods. There are also other implementation manners with single branches or multiple branches, and their effects are all to increase and decrease the pressure in the sealing cavity, including maintaining and releasing the pressure in the sealing cavity.

[0027] In the present application, a sealing ring 3-6 is provided on the piston, which improves the reliability of the sealing performance of the piston 3-3. Injecting hydraulic oil into the left and right sealing cavities can control the movement of the piston 3-3 through the pressure difference between the two, thereby driving the locking rod 3-1 to control the extension and retraction of the limit pressing block 3-11.

[0028] Specific implementation manner is as Figure 1 shown. When preparing to lock the hanger 7 after it is installed, first, the locking plug 5 should be closed to maintain the pressure in the left sealing cavity, and the unlocking plug 6 should be opened to release the pressure in the right sealing cavity. Then, the locking check valve 2 continuously injects hydraulic oil into the left sealing cavity. The hydraulic oil pushes the piston 3-3, thereby pushing the locking rod 3-1 forward until the locking rod 3-1 is pushed out of the upper ring groove of the main diameter of the tubing head body 1. After the front inclined surface of the limit pressing block 3-11 contacts the inclined surface of the metal seal of the hanger 7, hydraulic oil should continue to be injected to convert the force for the limit pressing block 3-11 to move inward into the force for pressing the metal seal of the hanger 7 downward, triggering the sealing of the metal seal ring of the hanger 7 until the outer scale line of the locking rod 3-1 is flush with the outer cylindrical surface of the upper flange 8 of the tubing head body 1, making the sealing performance of the hanger 7 more reliable. After stopping the injection of hydraulic oil, tighten the locking plug 5. The locking check valve 2 can ensure that the pressure in the sealing cavity does not leak, preventing the hanger 7 from moving back up due to well pressure.

[0029] When it is necessary to remove the hanger 7 or the wear sleeve or unlock the hanger 7, as Figure 2 shown, first, the locking plug 5 should be opened to release the pressure in the left sealing cavity, and then the unlocking plug 6 should be closed to maintain the pressure in the right sealing cavity. Then, control the unlocking check valve 4 to continuously inject hydraulic oil into the right sealing cavity. The hydraulic oil pushes the piston outward, driving the locking rod 3-1 to retract until the locking rod 3-1 is retracted into the main diameter ring groove of the tubing head body 1. At this time, the limit pressing block 3-11 has retracted into the upper ring groove of the main diameter of the tubing head body 1, and the hanger 7 can be smoothly taken out upward to complete the unlocking.

[0030] In this application, the locking check valve 2 and the unlocking check valve 4 adopt electric check valves, and the semi-automatic operation mode is more efficient. The working principle of using a check valve plus a plug to pressurize and depressurize the sealing cavity is adopted to lock and unlock the locking structure. Compared with manually using a wrench to tighten or other operation modes that require manual intervention, it is more convenient, labor-saving, and efficient. Compared with the easy thread slipping, this method is not easy to fail.

[0031] In this application, the outer circle of the above-mentioned outer sleeve is provided with a sealing ring 3-5 and the inner hole is provided with a sealing ring 3-2. The outer circle of the above-mentioned inner sleeve is provided with a sealing ring 3-8, and the inner hole is provided with a sealing ring 3-9. It maintains the corresponding sealing space and can also meet the requirements of annulus pressure test, ensuring the functional stability of the hydraulic locking structure, protecting the hydraulic cavity, avoiding external interference, avoiding the escape of the medium in the cavity, effectively preventing dust, and avoiding interference.

[0032] In this application, when the front end of the limit pressing block 3-11 is pushed out of the main diameter ring groove by the locking rod 3-1, there is a space for the limit pressing block 3-11 to retreat between the rear end face of the limit pressing block 3-11 and the inner side wall in the main diameter ring groove. It is convenient to release the lock on the hanger 7. The unlocking of the hanger 7 can be realized without completely removing the above-mentioned locking structure. The unlocking method is simpler. When the hanger 7 is to be taken out, only the limit pressing block 3-11 needs to be retracted into the main diameter ring groove, and then it can be taken out.

[0033] In this application, when the limit pressing block 3-11 is in conical surface fit and locked with the metal seal of the hanger 7, the space for the limit pressing block 3-11 to retreat corresponds to the distance that the piston moves to the left. When retreating, it can be avoided that the front end of the limit pressing block 3-11 cannot completely retreat into the main diameter ring groove, resulting in a series of problems such as the hanger 7 cannot be taken out and replaced, and it can also avoid resource waste caused by excessive retreat and excessive locking.

[0034] In this application, multiple scale lines are provided on the outer circle of the tail end of the locking rod 3-1, which can indicate the position of the locking rod 3-1. When locking, the unlocking plug 6 is opened to release pressure, and hydraulic oil is continuously injected through the locking check valve 2. The locking rod 3-1 is pushed forward until the outer scale line of the locking rod 3-1 is flush with the outer circumferential surface of the upper flange of the tubing head body 1; when unlocking, after lifting the upper flange 8, the locking plug 5 is opened to release pressure, and hydraulic oil is injected through the unlocking check valve 4 to make the locking rod 3-1 retreat until the inner scale line is flush with the outer circumferential surface of the upper flange 8 of the tubing head.

[0035] In this application, the tail end of the locking rod 3-1 is designed as a square, which is convenient for the disassembly and assembly of the locking rod 3-1 and the limit pressing block 3-11. Compared with being set as a hexagon, the processing is also simpler.

[0036] In this application, the inner sleeve 3-7 and the outer sleeve 3-4 are fixed to the through round hole by using an inner hexagon screw 3-10. It has reliable functions, simple structure, and is convenient to disassemble, enabling quick replacement of its components.

[0037] To better understand the present invention, a complete description of the working principle of the present invention is given below: During use, after installing the hanger 7 or the wear-resistant sleeve, this application can simply and effectively fix the hanger 7 and the wear-resistant sleeve. Similar to the traditional set screw, as Figure 5 shown, it passes through the set through round hole to clamp the hanger 7 or the wear-resistant sleeve. The difference is that this application is provided with a limit pressing block 3-11. The surface of the limit pressing block 3-11 in contact with the hanger 7 or the wear-resistant sleeve is a conical surface, which can complete a conical surface fit with the metal seal of the hanger 7. The advantages of the conical surface fit are obvious, more stable, more reliable, and with stronger load-bearing capacity. Another aspect is the operation method. The traditional operation is to tighten or loosen the locking device manually using a wrench. This manual operation method is not only cumbersome but also not safe and inefficient. This application has invented a hydraulic system. The user can use the hydraulic system to control the activation and release of the locking structure, which is more labor-saving and worry-free. The specific working principle is that after installing the hanger 7, open the unlocking plug 6 to relieve pressure, close the locking plug 5 to maintain pressure, continuously inject hydraulic oil through the locking check valve 2, push the locking rod 3-1 to move inward, and the limit pressing block 3-11 extends out of the main through-hole ring groove to clamp the hanger 7. When unlocking, it is the opposite. Close the unlocking plug 6, open the locking plug 5, inject hydraulic oil inward through the unlocking check valve 4, push the locking rod 3-1 to move outward, and the limit pressing block 3-11 retracts into the main through-hole ring groove to achieve unlocking of the hanger 7.

[0038] The above has specifically described the implementation mode of the present invention, but the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent variations or substitutions without departing from the spirit of the present invention, and these equivalents or substitutions are all included within the scope defined by the claims of the present invention.

Claims

1. A hydraulic locking structure for preventing the hanger from running up, comprising a tubing head body (1), a locking assembly (3) and a hanger (7). A main diameter ring groove is provided on the tubing head body (1), and a through-round hole for assembling the locking assembly (3) is provided on the inner side behind the main diameter ring groove. It is characterized in that: The locking assembly (3) mainly includes an inner sleeve (3-7), an outer sleeve (3-4), a locking rod (3-1) and a limit pressing block (3-11). The inner sleeve (3-7) and the outer sleeve (3-4) are respectively inserted into both ends of the through-round hole and fixed; the limit pressing block (3-11) is installed in the main diameter ring groove, the locking rod (3-1) passes through the inner sleeve (3-7) and the outer sleeve (3-4) and is threadedly connected with the limit pressing block (3-11), and the locking rod (3-1) drives the limit pressing block (3-11) to extend out, and the front end face of the limit pressing block (3-11) is in tapered fit with the metal seal of the hanger (7) for locking; A hydraulic system is also provided. The hydraulic system includes a first hydraulic passage, a second hydraulic passage and a piston (3-3). The piston (3-3) is assembled in the middle section of the locking rod (3-1), located between the inner sleeve (3-7) and the outer sleeve (3-4). The piston (3-3) forms two left and right sealed cavities between the through-round hole and the locking assembly (3). The left sealed cavity is connected to the first hydraulic passage, and the right sealed cavity is connected to the second hydraulic passage. By controlling the pressure difference between the two sealed cavities, the movement of the piston (3-3) is controlled, thereby driving the locking rod (3-1) to move left and right, achieving the effect of making the limit pressing block (3-11) extend out and retract.

2. The hydraulic locking structure for preventing the hanger from moving upward as described in claim 1, wherein, The first hydraulic passage includes a first branch, a second branch, a locking check valve (2) and a locking plug (5). The first branch penetrates from the upper end face of the tubing head body (1) to the left sealed cavity, and the locking plug (5) is arranged at the upper end face outlet. The second branch penetrates from the outer circumference direction of the tubing head body (1) to the confluence of the first branch passage, and the locking check valve (2) is arranged at the outer circumference outlet; the second hydraulic passage includes a first branch, a second branch, an unlocking check valve (4) and an unlocking plug (6). The first branch penetrates from the lower end face of the tubing head body (1) to the right sealed cavity, and the unlocking plug (6) is arranged at the lower end face outlet. The second branch penetrates from the outer circumference direction of the tubing head body (1) to the confluence of the first branch passage, and the unlocking check valve (4) is arranged at the outer circumference outlet.

3. The hydraulic locking structure for preventing the hanger from moving upward as claimed in claim 1, wherein A sealing ring (3-6) is provided on the piston (3-3).

4. The hydraulic locking structure for preventing the hanger from moving upward as claimed in claim 1, wherein The locking check valve (2) and the unlocking check valve (4) adopt electric check valves.

5. The hydraulic locking structure for preventing the hanger from moving upward as claimed in claim 1, wherein Sealing rings (3-5) are provided on the outer circumference of the outer sleeve and sealing rings (3-2) are provided in the inner hole, and sealing rings (3-8) are provided on the outer circumference of the inner sleeve and sealing rings (3-9) are provided in the inner hole.

6. The hydraulic locking structure for preventing the hanger from moving upward as described in claim 1, characterized in that, When the front end of the limit pressing block (3-11) is pushed out of the main diameter ring groove by the locking rod (3-1), there is a space for the limit pressing block (3-11) to retract between the rear end face of the limit pressing block (3-11) and the inner side wall in the main diameter ring groove.

7. The hydraulic locking structure for preventing the hanger from moving upward as claimed in claim 1, wherein When the limit pressing block (3-11) is locked in cooperation with the conical surface of the metal seal, the space for the limit pressing block (3-11) to retract corresponds to the maximum distance that the piston (3-3) moves to the left.

8. The hydraulic locking structure for preventing the hanger from moving upward as claimed in claim 1, wherein Multiple scale lines are provided on the outer circumference of the tail end of the locking rod (3-1), which can indicate the position of the locking rod (3-1).

9. The hydraulic locking structure for preventing the hanger from moving upward as described in claim 1, wherein, The tail end of the locking rod (3-1) is designed as a square.

10. A hydraulic locking structure for preventing the hanger from moving up, characterized in that, The inner sleeve (3-7) and the outer sleeve (3-4) are fixed to the through-round hole by screws (3-10).

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