Underground safety valve

Abstract

The utility model provides a subsurface safety valve, and relates to the technical field of subsurface tools in the petroleum and natural gas industry, the subsurface safety valve comprises an upper joint, a piston cylinder and a lower joint which are communicated in sequence, the piston cylinder is provided with at least two piston holes which are communicated with each other, each piston hole is internally provided with a piston assembly, and the piston cylinder is internally provided with a push rod; the push rod is clamped with the at least two piston assemblies; a closing device is arranged in the lower joint; at least two piston structures are adopted, namely, at least two piston holes provided with piston assemblies are formed, and the two piston holes are communicated, so that the pressures in the at least two piston holes are consistent, the at least two piston assemblies can be controlled by one hydraulic control pipeline, and the activation area of the piston is increased by the at least two piston assemblies; the pressure needed to be released when the pressure control pipeline drives the push rod to move through the piston assembly is reduced, then the hydraulic force needed to be provided when the subsurface safety valve is opened is reduced, and deformation and damage of the subsurface safety valve caused by large valve opening pressure are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of downhole tools in the oil and gas industry, and in particular to a downhole safety valve. Background Art

[0002] In the field of oil and gas completion technology, downhole safety valve is an emergency safety device during completion operations. When oil and gas wells are conducting downhole production operations, they often encounter situations where downhole fluid pressure and flow rate increase due to some reason, such as blowouts and well slugs. By closing the safety valve, potential risks or accidents can be avoided. In recent years, with the expansion of oil and gas resource development into deep formations, deep wells and ultra-deep wells have grown rapidly. It is expected that many 10,000-meter deep wells will be drilled during the 14th Five-Year Plan period. Deep wells and ultra-deep wells are often accompanied by extreme and harsh well conditions. The domestic market has an urgent demand for high-performance downhole safety valves.

[0003] In order to quickly control the opening and closing of the downhole safety valve, a hydraulic cylinder is usually used on the ground to control the opening and closing of the downhole safety valve to ensure the safe operation of the wellhead. However, in the prior art, the valve opening pressure of the downhole safety valve is too large. Especially in deep well operations, the large valve opening pressure can easily cause deformation and damage of the downhole safety valve. Utility Model Content

[0004] In view of the deficiencies in the prior art, the present application provides a downhole safety valve.

[0005] A downhole safety valve disclosed in the present application comprises: an upper joint, a piston cylinder and a lower joint which are connected in sequence, the piston cylinder is provided with at least two piston holes which are connected to each other, a piston assembly is provided in each piston hole, the piston cylinder has a piston cavity, a push rod is provided in the piston cylinder, the push rod is clamped with at least two piston assemblies, and a closing device is provided in the lower joint; when the downhole safety valve is in a closed state, the closing device is blocked in the lower joint, and the lower joint is not connected with the upper joint; when the downhole safety valve is in an open state, the push rod pushes and opens the closing device, and the lower joint is connected with the upper joint.

[0006] Preferably, the downhole safety valve further comprises a spring cylinder, which is located between the piston cylinder and the lower joint, and whose inner wall has a first shoulder. A power spring is arranged in the spring cylinder, and both ends of the power spring are respectively in contact with the first shoulder and the piston assembly.

[0007] Preferably, the piston assembly includes a piston, a piston rod, a piston rod retainer and a bearing member. The bearing member abuts against the power spring. The piston rod retainer is located at the end of the bearing member facing away from the power spring and is fixedly connected to the bearing member. The piston rod is slidably disposed in the piston hole and is clamped with the piston rod retainer. The piston is slidably disposed in the piston hole and is connected to the piston rod. The push rod has a second shoulder, which is clamped between the piston rod retainer and the bearing member.

[0008] Preferably, the piston assembly also includes a piston seat and a positioning seal. The piston seat is fixedly arranged on the end of the piston facing away from the piston rod. The inner wall of the piston hole has a first sealing surface. The first sealing surface is located at the end of the piston hole facing the upward joint. When the piston seat abuts against the first sealing surface, the piston seat and the first sealing surface form a metal seal. The positioning seal is fixedly arranged on the inner wall of the piston hole and is located at the end of the piston hole facing the downward joint. The piston rod has a second sealing surface. When the second sealing surface abuts against the positioning seal, the second sealing surface and the positioning seal form a metal seal.

[0009] Preferably, the closing device includes a closing component and a reset component, the closing component includes a valve seat and a valve plate, the valve seat is arranged in the lower joint, one end of the valve plate is rotatably connected to the valve seat, and the other end abuts against the valve seat, the reset component is arranged in the lower joint and rotatably connected to the valve plate; when the closing component is closed, the valve plate and the valve seat block the lower joint.

[0010] Preferably, the reset assembly includes a valve plate sleeve, a compression spring, a valve plate piston rod and a connecting beam. The valve plate sleeve is fixedly connected to the valve seat. The valve plate sleeve has a bypass hole. The valve plate piston rod and the compression spring are both arranged in the bypass hole. One end of the compression spring abuts against the valve plate piston rod, and the other end abuts against the bottom wall of the bypass hole. One end of the connecting beam is connected to the valve plate piston rod, and the other end is rotatably connected to the valve plate.

[0011] Preferably, the closing assembly also includes two support blocks, which are located on the side of the valve plate facing the upper joint. The two support blocks are respectively located at opposite ends of the valve plate and connected to the valve seat; when the downhole safety valve is in a closed state, the valve plate abuts against the support block and the valve seat respectively.

[0012] Preferably, the valve plate is arc-shaped, and the side of the valve plate facing the upper joint has two convex parts and two concave parts, which are alternately arranged around the periphery of the valve plate, the two convex parts respectively abut against the valve seat, and the two concave parts respectively abut against the support block.

[0013] Preferably, the downhole safety valve also includes a forced valve opening component, which includes a locking sleeve and a locking ring. The locking sleeve is arranged in the upper joint, and its inner wall has a locking section and its outer wall has a serrated thread. The locking ring is clamped between the upper joint and the piston cylinder, and forms a one-way movable fit with the serrated thread.

[0014] Preferably, the piston cylinder is also provided with a connecting hole and a shear plug, the connecting hole is connected with the piston hole and the piston cavity, the shear plug is arranged in the connecting hole and is clamped with the locking sleeve.

[0015] The beneficial effect of the present application is that by adopting at least two piston structures, that is, providing at least two piston holes with piston assemblies, and connecting the two piston holes, the pressure in the at least two piston holes is made consistent, and one hydraulic control pipeline can be used to control the at least two piston assemblies. The at least two piston assemblies increase the activation area of ​​the piston, reduce the pressure that needs to be released by the pressure-controlled pipeline to drive the push rod to move through the piston assembly, and thus reduce the hydraulic pressure required to be provided when the downhole safety valve is opened, avoiding deformation and damage of the downhole safety valve caused by a large valve opening pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0017] Figure 1 This is a schematic diagram of the structure of a downhole safety valve in an embodiment;

[0018] Figure 2 This is an exploded view of a downhole safety valve in an embodiment;

[0019] Figure 3 A three-dimensional diagram of a piston cylinder and a piston assembly in an embodiment;

[0020] Figure 4 is a cross-sectional view of a piston cylinder in an embodiment;

[0021] Figure 5 for Figure 4 A magnified image of area A;

[0022] Figure 6 A cross-sectional view of a spring cylinder in an embodiment;

[0023] Figure 7 for Figure 4 Enlarged view of area B;

[0024] Figure 8 This is a schematic diagram of the piston seat structure in the embodiment;

[0025] Fig. 9 for Figure 4 Enlarged view of area C in the middle;

[0026] Fig.10 for Figure 5 Section view of section aa in the middle;

[0027] Fig.11 is a cross-sectional view of the closing device in the downhole safety valve closed state in the embodiment;

[0028] Fig.12 It is a cross-sectional view of the closing device in the downhole safety valve open state in the embodiment;

[0029] Fig.13 Schematic diagram of the matching relationship between the valve seat and the valve plate in the embodiment;

[0030] Fig.14 A three-dimensional diagram of the valve plate in the embodiment;

[0031] Fig.15 A three-dimensional diagram of a support block in an embodiment;

[0032] Fig.16 Schematic diagram of the cooperation between the locking sleeve and the locking ring in the embodiment.

[0033] Reference numerals:

[0034] 10-upper joint; 20-piston cylinder; 30-lower joint; 40-spring cylinder;

[0035] 201-piston hole; 202-piston cavity; 203-communication hole; 204-shear plug; 205-control pressure transmission pipeline;

[0036] 401-first shoulder;

[0037] 2011-first sealing surface; 2041-blocking portion; 2042-connecting portion;

[0038] 1-piston assembly; 2-closing device; 3-push rod; 4-power spring; 5-forced valve opening member;

[0039] 11-piston; 12-piston rod; 13-piston rod retainer; 14-bearing member; 15-piston seat; 16-positioning seal;

[0040] 21-closing assembly; 22-resetting assembly;

[0041] 31- second shoulder;

[0042] 51-lock sleeve; 52-lock ring;

[0043] 121- second sealing surface;

[0044] 151-first chamfer;

[0045] 161- second chamfer;

[0046] 211-valve seat; 212-valve plate; 213-support block;

[0047] 221-valve plate sleeve; 222-compression spring; 223-valve plate piston rod; 224-connecting beam;

[0048] 511-locking profile; 512-serrated thread;

[0049] 2121-convex part; 2122-concave part;

[0050] 2211-Bypass hole. DETAILED DESCRIPTION

[0051] The following will disclose multiple embodiments of the present application with drawings. For the purpose of clear description, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present application. In other words, in some embodiments of the present application, these practical details are not necessary. In addition, in order to simplify the drawings, some conventional structures and components will be depicted in a simple schematic manner in the drawings.

[0052] It should be noted that all directional indications such as up, down, left, right, front, back... in the embodiments of the present application are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture as shown in the accompanying drawings. If the specific posture changes, the directional indication will also change accordingly.

[0053] In addition, in the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present application. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0054] In order to further understand the application content, features and effects of the present application, the following embodiments are cited and described in detail with reference to the accompanying drawings.

[0055] See also Figure 1 and Figure 2 The downhole safety valve in this example includes an upper joint 10, a piston cylinder 20, a lower joint 30, a push rod 3, a piston assembly 1 and a closing device 2. The piston cylinder 20 is used to load the piston assembly 1, the piston assembly 1 is used to control the movement of the push rod 3, and the push rod 3 is used to open the closing device 2, that is, to open the downhole safety valve. When in use, the upper joint 10 and the lower joint 30 are respectively used to connect the central pipeline of the oil pipe.

[0056] See also Figure 3 and Figure 4, wherein the upper joint 10, the piston cylinder 20 and the lower joint 30 are connected in sequence from top to bottom, and at least two piston holes 201 are provided in the piston cylinder 20. In this example, the number of piston holes 201 is two, and the two plug holes are respectively arranged on opposite sides of the piston cylinder 20 in a direction parallel to the length of the piston cylinder 20. The two plug holes are connected through a control pressure transmission pipeline 205, and a cavity can also be arranged to connect the two plug holes. When in use, the hydraulic control pipeline of the ground hydraulic control device is connected to one of the piston holes 201, and a piston assembly 1 is arranged in each piston hole 201, and the piston assembly 1 slides with the inner wall of the piston hole 201 The push rod 3 is connected in the piston cylinder 20. The push rod 3 is cylindrical and is engaged with the piston assembly 1 and moves with the piston assembly 1. The closing device 2 is arranged in the lower joint 30. When the downhole safety valve is in an open state, the lower joint 30 is connected with the upper joint 10, and the end of the push rod 3 facing away from the upper joint 10 is located in the lower joint 30. The push rod 3 pushes and opens the closing device 2. When the downhole safety valve is in a closed state, the closing device 2 is blocked in the lower joint 30, and the upper joint 10 is not connected with the lower joint 30. The end of the push rod 3 facing away from the upper joint 10 is located in the piston cylinder 20.

[0057] In specific applications, under normal circumstances, the downhole safety valve is in a normally open state, the ground hydraulic control device applies pressure to the piston hole 201, the piston assembly 1 moves toward the lower joint 30, and the push rod 3 follows the piston assembly 1 to move toward the lower joint 30. When the push rod 3 abuts against the closing device 2, the push rod 3 pushes and opens the closing device 2 until the push rod 3 completely opens the closing device 2, and the downhole safety valve is in an open state; when the downhole safety valve needs to be closed, the pressure in the piston hole 201 is released by the ground hydraulic control device. Under the action of the pressure of the ground hydraulic control device, the piston assembly 1 drives the push rod 3 to move in the direction away from the lower joint 30, the push rod 3 no longer abuts against the closing device 2, the closing device 2 loses the support of the push rod 3 and closes upward, the closing device 2 forms a seal with the lower joint 30, and the downhole safety valve is in a closed state.

[0058] By adopting at least two piston structures, that is, setting at least two piston holes 201 with piston assemblies 1, and connecting the two piston holes 201, the pressure in the at least two piston holes 201 is made consistent, and at least two piston assemblies 1 can be controlled by one hydraulic control pipeline. The at least two piston assemblies 1 increase the activation area of ​​the piston, reduce the pressure that needs to be released by the pressure control pipeline to drive the push rod 3 to move through the piston assembly 1, and thus reduce the hydraulic pressure required to be provided when the downhole safety valve is opened, avoiding deformation and damage of the downhole safety valve caused by a large valve opening pressure.

[0059] See also Figure 5 and Figure 6Furthermore, the downhole safety valve also includes a spring cylinder 40, the upper joint 10, the piston cylinder 20, the spring cylinder 40 and the lower joint 30 are connected in sequence, the inner wall of the spring cylinder 40 has a first shoulder 401, the first shoulder 401 is located at one end of the spring cylinder 40 close to the lower joint 30, and a power spring 4 is arranged in the spring cylinder 40, the power spring 4 is located between the inner wall surface of the spring cylinder 40 and the outer wall surface of the push rod 3, and is located between the upper wall surface of the first shoulder 401 and the lower wall surface of the piston assembly 1, and its two ends are respectively abutted against the first shoulder 401 and the piston hole 201.

[0060] When the hydraulic control pipeline provides hydraulic pressure to open the downhole safety valve, the piston assembly 1 moves toward the lower joint 30 and squeezes the power spring 4. When the downhole safety valve is in an open state, the power spring 4 is in a compressed state. When the downhole safety valve needs to be closed, the power spring 4 can provide elastic force to assist the push rod 3 to move toward the upper joint 10 to close the downhole safety valve.

[0061] Furthermore, the piston assembly 1 includes a piston 11, a piston rod 12, a piston rod retainer 13 and a bearing member 14. The piston 11 is arranged in the piston hole 201. The piston rod 12 is located at one end of the piston back-up joint 10, one end of which is connected to the piston 11, and the other end extends to the outside of the piston hole 201. The piston rod retainer 13 is cylindrical and is connected to the piston rod 12 through a fastening nut. The bearing member 14 is located at one end of the piston rod retainer 13 back-up joint 10, and is connected to the piston rod retainer 13 through a thread. One end of the bearing member 14 facing the downward joint 30 abuts against the power spring 4. The piston rod retainer 13 and the bearing member 14 are both arranged outside the push rod 3. The outer wall of the push rod 3 has a second shoulder 31, and the second shoulder 31 is clamped between the piston rod retainer 13 and the bearing member 14.

[0062] When the hydraulic control pipeline provides hydraulic pressure to open the downhole safety valve, the piston 11 moves in the piston hole 201, and the piston 11 drives the piston rod 12, the piston rod retainer 13 and the bearing member 14 to move. The piston rod retainer 13 drives the push rod 3 to move through the second shoulder 31, thereby realizing the opening of the downhole safety valve; when the pressure of the piston hole 201 is released to close the downhole safety valve, the power spring 4 pushes the bearing member 14 toward the upper joint 10, and the bearing member 14 drives the push rod 3 to move through the second shoulder 31 to assist in closing the downhole safety valve.

[0063] By arranging the bearing member 14 between the piston rod retainer 13 and the power spring 4 , deformation and distortion caused by excessive torque transmitted by the power spring 4 can be avoided.

[0064] See also Figure 7 , Figure 8 , Fig. 9 and Fig.10Furthermore, the piston assembly 1 also includes a piston seat 15 and a positioning seal 16. The piston seat 15 is fixedly arranged at one end of the piston 11 facing away from the piston rod 12, that is, fixedly arranged at one end of the piston 11 facing the upper joint 10. The piston seat 15 is made of metal material, and its upper surface has a first chamfer 151. The inner wall of the piston hole 201 has a first sealing surface 2011. The first sealing surface 2011 is located at the end of the piston hole 201 facing the upper joint 10. The first sealing surface 2011 is an inclined surface. When the piston seat 15 abuts against the first sealing surface 2011, the first chamfer 151 of the piston seat 15 and the inclined first sealing surface 2011 form a metal seal. At the same time, the first sealing surface 2011 limits the piston seat 15, and the piston seat 15 cannot continue to move toward the upper joint 10; the positioning seal 16 is arranged on the inner wall of the piston hole 201, and is located at the end of the piston hole 201 facing the lower joint 30, the upper surface of the positioning seal 16 has a second chamfer 161, and the end of the piston rod 12 facing the piston 11 has a second sealing surface 121, and the second sealing surface 121 is an inclined surface. When the second sealing surface 121 of the piston rod 12 abuts against the positioning seal 16, the second sealing surface 121 of the piston rod 12 and the chamfer of the positioning seal 16 form a metal seal. At the same time, the limiting seal limits the piston rod 12, and the piston rod 12 cannot continue to move toward the lower joint 30.

[0065] When the downhole safety valve is opened, the second sealing surface 121 of the piston rod 12 is sealed with the second chamfer 161 of the positioning seal 16, and the pressure and liquid in the lower joint 30 cannot enter the piston hole 201, thereby reducing the leakage rate of the safety valve. At the same time, the piston seat 15 and the positioning seal 16 are made of non-elastic sealing material with good sealing performance, which maintains stable and reliable performance under high-pressure working environment, and plays a role of double protection.

[0066] See also Fig.11 , Fig.12 and Fig.13 Furthermore, the closing device 2 includes a closing component 21 and a resetting component 22. The closing component 21 is used to seal the lower joint 30 to block the downhole safety valve, and the resetting component 22 is used to reset the closing component 21.

[0067] The closing assembly 21 includes a valve seat 211 and a valve plate 212. The valve seat 211 is fixed in the lower joint 30. In this example, the valve seat 211 is connected to one end of the spring cylinder 40 facing the lower joint 30 through a thread. If there is no spring cylinder 40, the valve seat 211 can be fixed to the piston cylinder 20. One end of the valve plate 212 is rotatably connected to the valve seat 211, and the other end is in contact with the valve seat 211. When the valve plate 212 is rotated to abut against the valve seat 211, the valve plate 212 and the valve seat 211 form a sealing fit, and the closing assembly 21 is closed. The reset assembly 22 includes a valve plate sleeve 221, compression spring 222, valve plate piston rod 223 and connecting beam 224, the valve plate sleeve 221 is fixed in the lower joint 30, and is located at the end of the valve seat 211 facing away from the upper joint 10, the valve plate sleeve 221 has a bypass hole 2211, the valve plate piston rod 223 and the compression spring 222 are both arranged in the bypass hole 2211, one end of the compression spring 222 abuts against the valve plate piston rod 223, and the other end abuts against the bottom wall of the bypass hole 2211, one end of the connecting beam 224 is rotatably connected to the valve plate piston rod 223, and the other end is rotatably connected to the valve plate 212.

[0068] In specific application, after the push rod 3 moves toward the lower joint 30 and abuts against the valve plate 212, the push rod 3 continues to move and pushes the valve plate 212 to rotate, the valve plate 212 rotates relative to the valve seat 211, and the valve plate 212 no longer abuts against the valve seat 211. When the push rod 3 pushes the valve plate 212 to rotate 90 degrees relative to the valve seat 211, that is, the valve plate 212 rotates from a horizontal setting to a vertical setting, the valve plate 212 is located between the push rod 3 and the lower joint 30, and the valve plate piston rod 223 squeezes the compression spring 222 under the action of the connecting beam 224, and the downhole safety valve is in an open state. The compression spring 222 is in a compressed state; when the downhole safety valve needs to be closed, the pressure in the piston hole 201 is released through the hydraulic control pipeline of the ground hydraulic control device, and the push rod 3 moves toward the upper joint 10. At this time, the valve plate 212 loses the support of the push rod 3, and the valve plate piston rod 223 moves toward the upper joint 10 under the action of the compression spring 222. The connecting beam 224 follows the movement of the valve plate piston rod 223 and drives the valve plate 212 to rotate until the valve plate 212 is sealed with the valve seat 211, and the downhole safety valve is closed. The valve plate 212 and the valve seat 211 cooperate to seal in the lower joint 30.

[0069] Furthermore, the closing component 21 also includes two support blocks 213, which are respectively located at opposite ends of the valve plate 212 and on the side of the valve plate 212 facing the upper joint 10. The two support blocks 213 are fixedly connected to the valve seat 211. When the valve seat 211 and the valve plate 212 are sealed together, the valve plate 212 abuts against the two support blocks 213.

[0070] In the extreme and harsh well conditions of deep wells and ultra-deep wells, for safety valves of the same specifications, while ensuring the pressure level, the outer diameter of the safety valve should be as small as possible, and the inner diameter should be as large as possible, so that the compatibility will be stronger and there will be more competitive advantages. In this application, the downhole safety valve has a small outer diameter and a large inner diameter, and the corresponding valve plate 212 is also relatively thin. The larger the outer diameter of the valve plate 212 and the thinner the wall thickness, the easier it is to deform when subjected to high pressure. By setting a support block 213, the valve plate 212 is supported when the downhole safety valve is closed, so that the valve plate 212 is subjected to more uniform force and is not easily deformed. In this way, the needs of deep well and ultra-deep well operations for downhole safety valves are met.

[0071] See also Fig.14 and Fig.15 Furthermore, the valve plate 212 is in an arc shape. When the downhole safety valve is closed, the side of the valve plate 212 facing the upper joint 10 has two convex portions 2121 and two concave portions 2122. The two convex portions 2121 and the two concave portions 2122 are respectively located around the valve plate 212, and the two convex portions 2121 and the two concave portions 2122 are alternately arranged around the periphery of the valve plate 212. The convex portion 2121 of the valve plate 212 abuts against the valve seat 211, and the concave portion 2122 of the valve plate 212 abuts against the support block 213. The shape of the support block 213 matches the shape of the concave portion 2122.

[0072] In this way, the valve plate 212 is set to an arc shape. When the downhole safety valve is opened, the valve plate 212 can fit with the lower joint 30, that is, the shape of the valve plate 212 matches the shape of part of the inner wall of the lower joint 30, thereby avoiding the valve plate 212 affecting the flow rate of the liquid in the valve when the downhole safety valve is opened.

[0073] See also Fig.16 Furthermore, the downhole safety valve also includes a forced valve opening component 5, which includes a locking sleeve 51 and a locking ring 52. The locking sleeve 51 is fixed to the upper joint 10 and the piston cylinder 20 by a sheath nail, and its inner wall surface has a locking section 511, and its outer wall surface has a serrated thread 512. The locking ring 52 is located between the upper joint 10 and the piston cylinder 20, and its upper end abuts against the upper joint 10, and its lower end abuts against the piston cylinder 20. The locking ring 52 and the serrated thread 512 of the locking sleeve 51 form a one-way moving fit, and the locking sleeve 51 has and can only move relative to the locking ring 52 toward the lower joint 30.

[0074] In actual application, when the downhole safety valve fails and needs to be forced to open, a special forced opening tool is lowered, and the forced opening tool is lowered to the locking section 511 of the lock sleeve 51. The forced opening tool is engaged with the locking section 511 and cannot be lowered further. At this time, the sealing member on the special forced opening tool forms a piston seal with the upper joint 10. The forced opening tool is pressurized by hydraulic pressure, and the forced opening tool drives the lock sleeve 51 to move toward the lower joint 30, fixing the lock sleeve The sheath nail of the tube 51 is therefore sheared off, and the pressure is continued to push the locking sleeve 51 to move downward. When the lower end of the locking sleeve 51 contacts and abuts the upper end of the push rod 3, the locking sleeve 51 pushes the push rod 3 to move downward. After the push rod 3 pushes the valve plate 212 to rotate to a vertical setting, the downhole safety valve gun is opened. After the locking sleeve 51 moves downward, a forced opening tool is pulled out from the well. Due to the one-way limit of the locking ring 52, the locking sleeve 51 and the push rod 3 cannot retreat, and the safety valve is in a permanently open state.

[0075] Review together Figure 3 , Figure 7 and Fig.10 Furthermore, the piston cylinder 20 has a piston cavity 202, the upper joint 10 and the lower joint 30 are connected through the piston cavity 202, the push rod 3 is arranged in the piston cavity 202, the piston cylinder 20 is also provided with a connecting hole 203 and a shear plug 204, the connecting hole 203 is connected to a piston hole 201 and the piston cavity 202, the shear plug 204 is arranged in the connecting hole 203, the shear plug 204 has a blocking portion 2041 and a connecting portion 2042, the connecting portion 2042 is arranged in the connecting hole 203, the blocking portion 2041 extends out of the connecting hole 203, and is engaged with the locking sleeve 51.

[0076] After the downhole safety valve is forcibly opened, the locking sleeve 51 moves downward, the shearing portion of the shear plug 204 is sheared by the locking sleeve 51, the blocking portion 2041 is separated from the connecting portion 2042, the piston hole 201 and the piston chamber 202 are connected, and then a wire-recoverable downhole safety valve is lowered into the downhole safety valve using a wire tool and seated on the upper joint 10. The sealing elements of the wire-recoverable downhole safety valve form a seal with the upper joint 10 and the lower joint 30 respectively, and the hydraulic control pipeline can control the opening and closing of the wire-recoverable downhole safety valve.

[0077] In summary, by adopting at least two piston structures, that is, setting at least two piston holes with piston assemblies, and connecting the two piston holes to make the pressure in the at least two piston holes consistent, it is possible to control the at least two piston assemblies with one hydraulic control pipeline. The at least two piston assemblies increase the activation area of ​​the piston, reduce the pressure that needs to be released by the pressure-controlled pipeline to drive the push rod to move through the piston assembly, and thus reduce the hydraulic pressure required to provide when the downhole safety valve is opened, avoiding deformation and damage of the downhole safety valve caused by a large valve opening pressure.

[0078] The above is only the implementation mode of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A downhole safety valve, characterized in that: The invention comprises an upper joint (10), a piston cylinder (20) and a lower joint (30) which are connected in sequence. The piston cylinder (20) is provided with at least two piston holes (201) which are connected with each other. A piston assembly (1) is arranged in each of the piston holes (201). The piston cylinder (20) has a piston cavity (202). A push rod (3) is arranged in the piston cylinder (20). The push rod (3) is engaged with at least two piston assemblies (1). A closing device (2) is arranged in the lower joint (30). When the downhole safety valve is in a closed state, the closing device (2) is blocked in the lower joint (30), and the lower joint (30) is not connected with the upper joint (10). When the downhole safety valve is in an open state, the push rod (3) pushes and opens the closing device (2), and the lower joint (30) is connected with the upper joint (10).

2. The downhole safety valve according to claim 1, characterized in that: The invention also comprises a spring cylinder (40), wherein the spring cylinder (40) is located between the piston cylinder (20) and the lower joint (30), and the inner wall of the spring cylinder (40) has a first shoulder (401). A power spring (4) is arranged in the spring cylinder (40), and the two ends of the power spring (4) are respectively in contact with the first shoulder (401) and the piston assembly (1).

3. The downhole safety valve according to claim 2, characterized in that: The piston assembly (1) comprises a piston (11), a piston rod (12), a piston rod retainer (13) and a bearing member (14); the bearing member (14) is in contact with the power spring (4); the piston rod retainer (13) is located at one end of the bearing member (14) facing away from the power spring (4) and is fixedly connected to the bearing member (14); the piston rod (12) is slidably disposed in the piston hole (201) and is clamped with the piston rod retainer (13); the piston (11) is slidably disposed in the piston hole (201) and is connected to the piston rod (12); the push rod (3) has a second shoulder (31); the second shoulder (31) is clamped between the piston rod retainer (13) and the bearing member (14).

4. The downhole safety valve according to claim 3, characterized in that: The piston assembly (1) further comprises a piston seat (15) and a positioning seal (16); the piston seat (15) is fixedly mounted on an end of the piston (11) facing away from the piston rod (12); the inner wall of the piston hole (201) comprises a first sealing surface (2011); the first sealing surface (2011) is located at an end of the piston hole (201) facing the upper joint (10); when the piston seat (15) abuts against the first sealing surface (2011), the piston rod (12) is secured to the piston seat (15); The piston seat (15) forms a metal seal with the first sealing surface (2011); the positioning seal (16) is fixedly arranged on the inner wall of the piston hole (201) and is located at one end of the piston hole (201) facing the lower joint (30); the piston rod (12) has a second sealing surface (121); when the second sealing surface (121) abuts against the positioning seal (16), the second sealing surface (121) and the positioning seal (16) form a metal seal.

5. The downhole safety valve according to claim 2, characterized in that: The closing device (2) comprises a closing component (21) and a reset component (22), the closing component (21) comprises a valve seat (211) and a valve plate (212), the valve seat (211) is arranged in the lower joint (30), one end of the valve plate (212) is rotatably connected to the valve seat (211), and the other end is in contact with the valve seat (211), the reset component (22) is arranged in the lower joint (30), and is rotatably connected to the valve plate (212); when the closing component (21) is closed, the valve plate (212) and the valve seat (211) block the lower joint (30).

6. The downhole safety valve according to claim 5, characterized in that: The reset assembly (22) includes a valve plate sleeve (221), a compression spring (222), a valve plate piston rod (223) and a connecting beam (224); the valve plate sleeve (221) is fixedly connected to the valve seat (211); the valve plate sleeve (221) has a bypass hole (2211); the valve plate piston rod (223) and the compression spring (222) are both arranged in the bypass hole (2211); one end of the compression spring (222) abuts against the valve plate piston rod (223), and the other end abuts against the bottom wall of the bypass hole (2211); one end of the connecting beam (224) is connected to the valve plate piston rod (223), and the other end is rotatably connected to the valve plate (212).

7. The downhole safety valve according to claim 5, characterized in that: The closing assembly (21) further comprises two support blocks (213), wherein the support blocks (213) are located on a side of the valve plate (212) facing the upper joint (10), and the two support blocks (213) are respectively located at opposite ends of the valve plate (212) and connected to the valve seat (211); when the downhole safety valve is in a closed state, the valve plate (212) abuts against the support blocks (213) and the valve seat (211), respectively.

8. The downhole safety valve according to claim 7, characterized in that: The valve plate (212) is arc-shaped, and the side of the valve plate (212) facing the upper joint (10) has two convex portions (2121) and two concave portions (2122), the two convex portions (2121) and the two concave portions (2122) are alternately arranged around the periphery of the valve plate (212), the two convex portions (2121) respectively abut against the valve seat (211), and the two concave portions (2122) respectively abut against the support block (213).

9. The downhole safety valve according to claim 1, characterized in that: The invention also includes a forced valve opening component (5), wherein the forced valve opening component (5) includes a locking sleeve (51) and a locking ring (52). The locking sleeve (51) is arranged in the upper joint (10), and its inner wall has a locking section (511), and its outer wall has a serrated thread (512). The locking ring (52) is clamped between the upper joint (10) and the piston cylinder (20), and forms a one-way movable fit with the serrated thread (512).

10. The downhole safety valve according to claim 9, characterized in that: The piston cylinder (20) is also provided with a connecting hole (203) and a shear plug (204). The connecting hole (203) is connected with the piston hole (201) and the piston cavity (202). The shear plug (204) is arranged in the connecting hole (203) and is engaged with the locking sleeve (51).

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