Downhole safety valve

Abstract

The subsurface safety valve comprises an upper connector and a lower connector, and a flow pipe is arranged in a center flow channel of the upper connector; a first through hole penetrating from top to bottom is formed in the upper connector, a piston rod is arranged in the first through hole, the piston rod is sleeved with a sealing structure, the sealing structure is used for sealing an annular space between the piston rod and the first through hole, the lower end of the piston rod is fixedly connected with a connecting sleeve, and the connecting sleeve is matched with the flowing pipe so that the flowing pipe can move along with the connecting sleeve; a first reset structure is arranged between the outer connecting cylinder below the connecting sleeve and the flowing pipe, and the first reset structure is configured to enable the connecting sleeve to be in contact with the upper connector; the lower end of the outer connecting cylinder is connected with a valve body assembly, the valve body assembly is in a first state in a normal state, and the flowing pipe moves downwards so that the valve body assembly can be switched from the first state to the second state. The safety valve has the beneficial effects of being simple in structure and operation, and the overall pressure resistance of the safety valve is high.

Description

Technical Field

[0001] The invention belongs to the technical field of downhole tools, and in particular relates to a downhole safety valve. Background Art

[0002] The downhole safety valve is a downhole tool that can be closed urgently when abnormal conditions occur in oil and gas wells to prevent blowouts and ensure the safety of oil and gas well production.

[0003] The existing downhole safety valves are not suitable for well conditions with high air tightness levels, have low overall pressure resistance, limited operating temperature, and short service life. In addition, during the operation of the safety valve, the seal on the piston rod is susceptible to high pressure, which is destructive to the seal and can easily lead to seal failure, thus affecting the service life of the safety valve. Summary of the invention

[0004] In order to solve all or part of the above problems, the present invention aims to provide a downhole safety valve. The downhole safety valve of the present invention has a high overall pressure resistance.

[0005] According to one aspect of the present invention, a downhole safety valve is provided, comprising an upper joint and a lower joint, wherein an outer connecting tube is fixedly connected to the outer side of the lower end of the upper joint, a flow pipe is arranged in the central flow channel of the upper joint, and the outer lower end of the outer connecting tube is fixedly connected to the lower joint;

[0006] The upper joint is provided with a first through hole which runs from top to bottom, a piston rod is arranged in the first through hole, a sealing structure is sleeved on the piston rod, the sealing structure is used to seal the annulus between the piston rod and the first through hole, a connecting sleeve is fixedly connected to the lower end of the piston rod, the connecting sleeve is located between the outer connecting tube and the flow pipe, and the connecting sleeve cooperates with the flow pipe so that the flow pipe can move with the connecting sleeve;

[0007] A first reset structure is provided between the outer connection tube and the flow tube below the connection sleeve, the lower end of the first reset structure is limited by the outer connection tube, and the first reset structure is configured to enable the connection sleeve to contact the upper joint;

[0008] The lower end of the external connecting tube is connected to a valve body assembly, and the valve body assembly is located in the lower joint. The valve body assembly has a first state of blocking the central flow channel of the external connecting tube, and a second state of not blocking the central flow channel of the external connecting tube. The valve body assembly is in the first state under normal conditions, and the downward movement of the flow tube can switch the valve body assembly from the first state to the second state.

[0009] Furthermore, a first retaining ring is provided on the piston rod, and the sealing structure comprises a first sealing member on the piston rod sleeved above the first retaining ring, and the first sealing member is sealingly connected to the first through hole;

[0010] An upper piston cap is fixedly connected to the upper end of the piston rod, and a first spring is arranged between the upper piston cap and the first sealing member, and the first spring is configured to press the first sealing member onto the first retaining ring.

[0011] Furthermore, the sealing structure further comprises a second sealing member sleeved on the piston rod below the first retaining ring, and the second sealing member is sealingly connected to the first through hole;

[0012] The sealing surface between the first baffle ring and the first seal and the sealing surface between the first baffle ring and the second seal intersect; or, the sealing surface between the first baffle ring and the first seal and the sealing surface between the first baffle ring and the second seal are both perpendicular to the axis of the piston rod.

[0013] Furthermore, the first seal and the second seal are both metal parts; the first seal and the second seal both have a head and an ear, the head respectively cooperates with the corresponding sides of the first retaining ring, the two heads are in contact with each other, and each of the heads is sleeved on the piston rod, the two ears extend in directions away from each other, and each of the ears is in contact with the inner wall of the first through hole; a wear-resistant ring is sleeved on the piston rod below the second seal.

[0014] Furthermore, the lower end of the upper joint is fixedly connected with a stop plug, the lower end of the piston rod is fixedly connected with a lower piston cap, the lower piston cap is fixedly connected to the connecting sleeve, and the first reset structure is configured to enable the lower piston cap to be in sealing contact with the stop plug.

[0015] Furthermore, a second retaining ring is fixedly provided on the inner side of the connecting sleeve, and a matching step is fixedly provided on the outer side wall of the flow tube, and the matching step is located below the second retaining ring. When the connecting sleeve moves downward, the matching between the second retaining ring and the matching step drives the flow tube to move downward.

[0016] The connecting sleeve below the matching step is fixedly connected with a retaining spring, and the connecting sleeve moves upwards, and the matching between the retaining spring and the matching step drives the flow tube to move upwards.

[0017] Furthermore, the first reset structure is a second spring; a first limiting ring is provided on the inner side wall of the lower part of the external connecting tube, a third retaining ring is provided in the flow tube above the first limiting ring, the third retaining ring is fixedly connected with a spring retaining ring, the lower end of the second spring is limited by the spring retaining ring, the upper end surface of the spring retaining ring is a first plane, and the lower end surface of the second spring is a second plane that fits with the first plane.

[0018] Further, the valve body assembly includes a valve seat and a valve plate, the valve seat is located in the lower joint, the valve seat is fixedly connected to the lower end of the external connection tube, the valve seat is rotatably connected to the valve plate, and a second reset structure is provided between the valve seat and the valve plate, and the second reset structure is configured to enable the valve plate to block the central flow channel of the valve seat;

[0019] The flow tube cooperates with the valve plate so that when the connecting sleeve contacts the upper joint, the valve plate blocks the central flow channel of the valve seat under the action of the second reset structure, so that the flow tube can contact the valve plate during the downward movement to drive the valve plate to rotate until the central flow channel of the valve seat is not blocked;

[0020] When the valve plate blocks the central flow channel of the valve seat, the valve body assembly is in a first state, and when the valve plate does not block the central flow channel of the valve seat, the valve body assembly is in a second state.

[0021] Furthermore, the lower end of the external connection tube is fixedly connected to a valve flap frame, and the valve seat is fixedly connected to the valve flap frame;

[0022] The valve seat is rotatably connected to the valve plate via a valve flap pin, and the valve flap pin is limited on the valve seat.

[0023] Furthermore, the second reset structure is a torsion spring; when the connecting sleeve contacts the upper joint, there is a gap between the lower end of the flow tube and the valve plate, so that when the connecting sleeve contacts the upper joint, the valve plate blocks the central flow channel of the valve seat under the action of the torsion spring.

[0024] Furthermore, a leaf spring is fixedly connected to the lower side of the valve plate, and a balancing valve is arranged on the valve plate. The leaf spring is configured to press the balancing valve onto the valve plate, and the upper end of the balancing valve extends upward to the top of the valve plate. The flow tube can contact the balancing valve during the downward movement, so that the valve plate can be rotated through the balancing valve to not block the central flow channel of the valve seat; when the connecting sleeve contacts the upper joint, a gap is provided between the lower end of the flow tube and the upper end of the balancing valve.

[0025] Furthermore, a second through hole and a third through hole are provided on the balancing valve, and the third through hole is connected to the second through hole. When the leaf spring presses the balancing valve into the mounting hole on the valve plate, the third through hole is located in the valve plate, and the balancing valve can be moved downward during the downward movement of the flow tube to connect the space above the valve plate and the space below the valve plate through the second through hole and the third through hole.

[0026] It can be seen from the above technical solution that the downhole safety valve provided by the present invention has the following beneficial effects:

[0027] The safety valve of the present invention has the advantages of simple structure and operation, and the overall pressure resistance of the safety valve of the present invention is relatively high;

[0028] The sealing structure of the present invention comprises a first sealing member and a second sealing member, wherein the larger pressure of the pressure acting on the first sealing member and the second sealing member is used to push the piston rod to move; the smaller pressure of the pressure acting on the first sealing member and the second sealing member is transmitted to the first retaining ring and the other sealing member through the sealing member, so that the pressure difference on both sides of the other sealing member is lower, thereby correspondingly improving the service life of the sealing structure;

[0029] The second seal of the present invention is also used to seal the annulus between the piston rod and the inner wall of the first through hole, thereby preventing liquid from passing through the second seal from the lower end of the first through hole into the upper end of the first through hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic diagram of a downhole safety valve according to an embodiment of the present invention;

[0031] Figure 2 In one embodiment Figure 1 A local enlarged view of point A;

[0032] Figure 3 In another embodiment Figure 1 A local enlarged view of point A;

[0033] Figure 4 for Figure 1 A local enlarged view of point B;

[0034] Figure 5 for Figure 1 Sectional view of section JJ;

[0035] Figure 6 for Figure 1 Cross-sectional view of the middle PP section;

[0036] Figure 7 It is a partial cross-sectional view of the balancing valve;

[0037] The reference numerals in the figure are: upper joint 1, external connecting tube 2, piston rod 3, upper piston cap 4, flow tube 5, valve seat 6, valve disc rack 7, first reset structure 8, valve disc pin 9, first spring 10, balancing valve 11, spring retaining ring 12, third retaining ring 13, wear-resistant ring 14, lower piston cap 15, stop plug 16, connecting sleeve 17, second reset structure 18, lower joint 19, leaf spring 20, retaining ring 21, valve plate 22, first sealing member 23, second sealing member 24, first retaining ring 25, second retaining ring 26, matching step 27, second through hole 28, third through hole 29. DETAILED DESCRIPTION

[0038] In order to better understand the purpose, structure and function of the present invention, a downhole safety valve of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0039] like Figure 1 As shown, it shows a downhole safety valve of an embodiment of the present invention, including an upper joint 1 and a lower joint 19, the outer side of the lower end of the upper joint 1 is fixedly connected with an outer connecting tube 2, a flow pipe 5 is arranged in the central flow channel of the upper joint 1, and the outer lower end of the outer connecting tube 2 is fixedly connected with the lower joint 19, wherein the upper joint 1 is used to be fixedly connected to the pipe column above it, and the lower joint 19 is used to be fixedly connected to the pipe column below it.

[0040] The upper joint 1 is provided with a first through hole that runs from top to bottom, a piston rod 3 is arranged in the first through hole, and a sealing structure is sleeved on the piston rod 3, and the sealing structure is used to seal the annulus between the piston rod 3 and the first through hole. The upper end of the first through hole cooperates with the pressure pipeline of the pressure equipment, and when the pressure is applied to the first through hole through the pressure equipment, the pressure acts on the sealing structure, so that the sealing structure and the piston rod 3 move downward.

[0041] The lower end of the piston rod 3 is fixedly connected with a connecting sleeve 17, which is located between the outer connecting tube 2 and the flow tube 5. The connecting sleeve 17 cooperates with the flow tube 5 so that the flow tube 5 can move with the connecting sleeve 17. Therefore, when the sealing structure and the piston rod 3 move downward, the connecting sleeve 17 can be driven to move downward; and the connecting sleeve 17 cooperates with the flow tube 5 so that the flow tube 5 can move with the connecting sleeve 17, so when the connecting sleeve 17 moves downward, the corresponding flow tube 5 moves downward.

[0042] In this embodiment, when the pressure above the sealing structure increases to overcome the friction between the sealing structure and the first through hole, the sealing structure moves downward. Therefore, the pressure acting on the sealing structure does not need to be too large to push the sealing structure downward, which correspondingly reduces the pressure on the sealing structure, increases the service life of the sealing structure, and increases the service life of the downhole safety valve.

[0043] Again, a first reset structure 8 is provided between the outer connecting tube 2 and the flow tube 5 below the connecting sleeve 17 , and the lower end of the first reset structure 8 is limited by the outer connecting tube 2 . The first reset structure 8 is configured to enable the connecting sleeve 17 to contact the upper joint 1 .

[0044] The specific first reset structure 8 is arranged between the external connecting tube 2 and the flow tube 5. The upper end of the first reset structure 8 is limited by the connecting sleeve 17, and the lower end of the first reset structure 8 is limited by the external connecting tube 2, thereby achieving the purpose of limiting the first reset structure 8 between the external connecting tube 2 and the flow tube 5.

[0045] The first reset structure 8 is configured to enable the connecting sleeve 17 to contact with the upper joint 1. Therefore, when the first through hole is pressed by the pressing device, the pressure acts on the sealing structure, thereby causing the sealing structure, the piston rod 3 and the connecting sleeve 17 to move downward. When the connecting sleeve 17 moves downward, the first reset structure 8 is compressed. When the pressing stops, the first reset structure 8 is no longer affected by the pressing pressure, and the first reset structure 8 is reset accordingly. The reset of the first reset structure 8 accordingly drives the connecting sleeve 17 to move upward, and finally the first reset structure 8 is reset to make the connecting sleeve 17 contact with the upper joint 1.

[0046] Finally, the lower end of the external connecting tube 2 is connected to a valve body assembly, which is located in the lower joint 19. The valve body assembly has a first state of blocking the central flow channel of the external connecting tube 2, and a second state of not blocking the central flow channel of the external connecting tube 2. The valve body assembly is in the first state under normal conditions, and the downward movement of the flow tube 5 can switch the valve body assembly from the first state to the second state.

[0047] Specifically, the valve body assembly of this embodiment has a first state and a second state. When the valve body assembly is in the first state, the valve body assembly blocks the central flow channel of the outer connecting tube 2, and when the valve body assembly is in the second state, the valve body assembly does not block the central flow channel of the outer connecting tube 2. In the process of the flow tube 5 moving downward with the connecting sleeve 17, after the flow tube 5 moves downward to contact the valve body assembly, the valve body assembly can be switched from the first state to the second state when the flow tube 5 continues to move downward; when the flow tube 5 moves upward with the connecting sleeve 17 to leave the valve body assembly, the valve body assembly returns to the first state under normal conditions.

[0048] During specific use, before production, the first through hole is first pressurized by a pressurizing device, so that the piston rod 3, the sealing structure and the connecting sleeve 17 move downward, and the connecting sleeve 17 moves downward along with the downward flow tube 5, thereby switching the valve body assembly from the first state to the second state. At this time, the valve body assembly does not block the central flow channel of the outer connecting tube 2, and the downhole oil and gas can smoothly enter the central flow channel of the outer connecting tube 2, thereby realizing the smooth progress of production; when an abnormality occurs in the downhole production process, the first through hole is no longer pressurized by a pressurizing device, and the piston rod 3 is reset under the action of the first reset structure 8. The reset of the piston rod 3 drives the flow tube 5 upward. After the flow tube 5 moves upward and leaves the valve body assembly, the valve body assembly returns to the first state under normal conditions. At this time, the valve body assembly blocks the central flow channel of the outer connecting tube 2, and the downhole oil and gas cannot enter the central flow channel of the outer connecting tube 2.

[0049] In one embodiment, a first retaining ring 25 is provided on the piston rod 3, and the sealing structure includes a first sealing member 23 sleeved on the piston rod 3 above the first retaining ring 25, and the first sealing member 23 is sealingly connected to the first through hole.

[0050] In this embodiment, the sealing structure includes a first seal 23, which is located above the first retaining ring 25, and the first seal 23 is sealed and connected to the first through hole on one hand, and is sleeved on the piston rod 3 by interference fit on the other hand, so the setting of the first seal 23 in this embodiment achieves the purpose of sealing the annular space between the piston rod 3 and the inner wall of the first through hole. Therefore, when the annular space above the first seal 23 is pressurized through the first through hole, the pressure pushes the first seal 23 and the piston rod 3 downward, thereby achieving the purpose of opening the central flow channel of the outer connecting tube 2 by the downward movement of the flow pipe 5.

[0051] Again, the upper end of the piston rod 3 is fixedly connected with the upper piston cap 4, and a first spring 10 is provided between the upper piston cap 4 and the first sealing member 23, and the first spring 10 is configured to press the first sealing member 23 onto the first retaining ring 25. The first spring 10 of this embodiment is used to press the first sealing member 23 onto the first retaining ring 25, so that the sealing surfaces between the first retaining ring 25 and the first sealing member 23 are effectively matched, so that the piston rod 3 can be effectively pushed downward.

[0052] In one embodiment, the sealing structure further comprises a second sealing member 24 sleeved on the piston rod 3 below the first retaining ring 25 , and the second sealing member 24 is sealedly connected to the first through hole. In this embodiment, the second sealing member 24 is sleeved on the piston rod 3 below the first retaining ring 25 .

[0053] The second sealing member 24 is also used to seal the annular space between the piston rod 3 and the inner wall of the first through hole, thereby preventing liquid from passing through the second sealing member 24 from the lower end of the first through hole into the upper end of the first through hole.

[0054] In a specific implementation, for example, the sealing surface between the first retaining ring 25 and the first sealing member 23 and the sealing surface between the first retaining ring 25 and the second sealing member 24 intersect. Figure 3 or for example, the sealing surface between the first baffle ring 25 and the first seal 23, and the sealing surface between the first baffle ring 25 and the second seal 24 are perpendicular to the axis of the piston rod 3, such as Figure 2 The above two situations can be achieved by setting a suitable cross-sectional shape of the first retaining ring 25.

[0055] In one embodiment, the first seal 23 and the second seal 24 are both metal parts; the first seal 23 and the second seal 24 both have a head and an ear, each head is respectively matched with the corresponding side of the first retaining ring 25, the two heads are in contact with each other, and each head is sleeved on the piston rod 3, the two ears extend in directions away from each other, and each ear is in contact with the inner wall of the first through hole; a wear-resistant ring 14 is sleeved on the piston rod 3 below the second seal 24.

[0056] In this embodiment, the first seal 23 and the second seal 24 both include a head and an ear, and the head is respectively arranged on both sides of the first retaining ring 25, and the two ears are arranged away from each other. In this embodiment, the first seal 23 and the second seal 24 are both metal parts. In specific implementation, as an extended solution, an elastic member can also be arranged to press the second seal 24 under the first retaining ring 25.

[0057] In the case of setting the first seal 23 and the second seal 24, the larger pressure acting on the first seal 23 and the second seal 24 during specific use will be used to push the piston rod 3 to move, that is, when the piston rod 3 needs to move downward, the liquid pressure acting on the first seal 23 is greater than the liquid pressure acting on the second seal 24; the smaller pressure acting on the first seal 23 and the second seal 24 will be transmitted to the first baffle ring 25 and the other seal through the seal, so that the pressure difference on both sides of the other seal is lower, that is, in the case of a smaller pressure acting on the second seal 24, the smaller pressure is transmitted to the first baffle ring 25 and the first seal 23, so that the pressure difference on both sides of the first seal 23 is smaller, thereby correspondingly improving the service life of the first seal 23, so that the downhole safety valve of the embodiment of the present invention can be used in oil wells with high downhole pressure and high temperature.

[0058] In one embodiment, the lower end of the upper joint 1 is fixedly connected with a stop plug 16, the lower end of the piston rod 3 is fixedly connected with a lower piston cap 15, the lower piston cap 15 is fixedly connected to the connecting sleeve 17, and the first reset structure 8 is configured to enable the lower piston cap 15 to be in sealing contact with the stop plug 16.

[0059] In this embodiment, a stop plug 16 is fixedly connected to the lower end of the upper joint 1, and a lower piston cap 15 is arranged between the lower end of the piston rod 3 and the connecting sleeve 17. The arrangement of the stop plug 16 and the lower piston cap 15 achieves the purpose of sealing contact between the lower piston cap 15 and the stop plug 16 after the first reset structure 8 is reset. The sealing contact between the two achieves the purpose of protecting the sealing structure, thereby also improving the service life of the first seal 23 and the second seal 24 at the sealing structure.

[0060] As can be seen from the above, the flow tube 5 can move with the connecting sleeve 17. Specifically, Figure 4 As shown, a second retaining ring 26 is fixedly provided on the inner side of the connecting sleeve 17, and a matching step 27 is fixedly provided on the outer wall of the flow tube 5. The matching step 27 is located below the second retaining ring 26. When the connecting sleeve 17 moves downward, the matching between the second retaining ring 26 and the matching step 27 drives the flow tube 5 downward. A retaining spring 21 is fixedly connected to the connecting sleeve 17 below the matching step 27. When the connecting sleeve 17 moves upward, the matching between the retaining spring 21 and the matching step 27 drives the flow tube 5 upward.

[0061] Specifically, the present embodiment realizes the purpose of the flow tube 5 following the connection sleeve 17 downward by setting the second retaining ring 26 and the matching step 27, and realizes the purpose of the flow tube 5 following the connection sleeve 17 upward by matching the matching step 27 and the clamping spring 21. In a specific implementation, for example, the second retaining ring 26, the matching step 27 and the clamping spring 21 are set such that when the clamping spring 21 contacts the matching step 27, there is a spacing between the matching step 27 and the second retaining ring 26; according to this setting, when the clamping spring 21 drives the matching step 27 to reset, and then presses again, the second retaining ring 26 first moves downward by the spacing until the second retaining ring 26 contacts the matching step 27, and then the matching step 27 follows downward under the drive of the second retaining ring 26; this setting can make the flow tube 5 run more smoothly.

[0062] In one embodiment, the first reset structure 8 is a second spring; a first limiting ring is provided on the inner side wall of the lower part of the external connecting tube 2, a third retaining ring 13 is provided in the flow tube 5 above the first limiting ring, the third retaining ring 13 is fixedly connected with a spring retaining ring 12, the lower end of the second spring is limited by the spring retaining ring 12, the upper end surface of the spring retaining ring 12 is a first plane, and the lower end surface of the second spring is a second plane that fits the first plane.

[0063] In this embodiment, the lower end of the first reset structure 8 is limited by the arrangement of the first limiting ring and the spring retaining ring 12, and the first reset structure 8 is limited between the connecting sleeve 17 and the spring retaining ring 12. The upper end surface of the spring retaining ring 12 is a first plane, and the lower end surface of the second spring is a second plane that fits the first plane. In this embodiment, the contact between the second spring and the spring retaining ring 12 is a surface contact by the arrangement of the first plane and the second plane.

[0064] In one embodiment, if Figure 5 As shown, the valve body assembly includes a valve seat 6 and a valve plate 22, the valve seat 6 is located in the lower joint 19, the valve seat 6 is fixedly connected to the lower end of the external connecting tube 2, the valve seat 6 is rotatably connected to the valve plate 22, and a second reset structure 18 is provided between the valve seat 6 and the valve plate 22, the second reset structure 18 is configured to enable the valve plate 22 to block the central flow channel of the valve seat 6; and the flow tube 5 cooperates with the valve plate 22 so that when the connecting sleeve 17 contacts the upper joint 1, the valve plate 22 blocks the central flow channel of the valve seat 6 under the action of the second reset structure 18, so that the flow tube 5 can contact the valve plate 22 during the downward movement to drive the valve plate 22 to rotate to not block the central flow channel of the valve seat 6; when the valve plate 22 blocks the central flow channel of the valve seat 6, the valve body assembly is in a first state, and when the valve plate 22 does not block the central flow channel of the valve seat 6, the valve body assembly is in a second state.

[0065] In this embodiment, the valve body assembly includes a valve seat 6 and a valve plate 22, and the valve seat 6 and the valve plate 22 are rotatably connected, for example, by a valve flap pin 9, and the valve flap pin 9 is limited on the valve seat 6, and the outer sleeve of the valve flap pin 9 is provided with a pin sleeve, wherein the lower end of the external connecting tube 2 is fixedly connected to the valve flap frame 7, and the valve seat 6 is fixedly connected to the valve flap frame 7; a second reset structure 18 is arranged between the valve seat 6 and the valve plate 22, and the second reset structure 18 of this embodiment is arranged to enable the valve plate 22 to block the central flow channel of the valve seat 6, specifically, for example, the second reset structure 18 is a torsion spring sleeved on the valve flap pin 9; wherein when the valve plate 22 blocks the central flow channel of the valve seat 6, the valve body assembly is in a first state, and when the valve plate 22 does not block the central flow channel of the valve seat 6, the valve body assembly is in a second state.

[0066] This embodiment also requires the flow tube 5 to cooperate with the valve plate 22, so that when the connecting sleeve 17 contacts the upper joint 1, the valve plate 22 blocks the central flow channel of the valve seat 6 under the action of the second reset structure 18, wherein the flow tube 5 is in the upper limit position when the connecting sleeve 17 contacts the upper joint 1, that is, when the flow tube 5 is in the upper limit position, the valve plate 22 is in a state of blocking the central flow channel of the valve seat 6. For example, when the flow tube 5 is in the upper limit position, a gap is set between the lower end of the flow tube 5 and the valve plate 22, so that the valve plate 22 can block the central flow channel of the valve seat 6 under the action of the second reset structure 18 at this time.

[0067] Finally, when the flow tube 5 is at the upper limit position, the gap between the lower end of the flow tube 5 and the valve plate 22 needs to be sufficient to enable the flow tube 5 to push open the valve plate 22 during its downward movement.

[0068] Specifically, before the annular space above the first sealing member 23 is pressurized through the first through hole, the connecting sleeve 17 is in the upper limit position under the action of the first reset structure 8, at which time the lower piston cap 15 is in sealing contact with the stop plug 16, the flow tube 5 is in the upper limit position, and there is a gap between the lower end of the flow tube 5 and the valve plate 22, and the valve plate 22 is in a state of blocking the central flow channel of the valve seat 6 under the action of the second reset structure 18; when the annular space above the first sealing member 23 is pressurized through the first through hole, the connecting sleeve 17 moves downward first, and when the connecting sleeve 17 moves downward until the second retaining ring 26 and the matching step 27 come into contact, the flow tube 5 moves downward with the connecting sleeve 17, and the flow tube 5 gradually approaches the valve plate 22 during the downward movement, and when the flow tube 5 contacts the valve plate 22, the downward movement of the flow tube 5 drives the valve plate 22 to rotate, thereby switching the valve plate 22 to a state of not blocking the central flow channel of the valve seat 6.

[0069] In one embodiment, if Figure 6-Figure 7 As shown, a leaf spring 20 is fixedly connected to the lower side of the valve plate 22, and a balancing valve 11 is arranged on the valve plate 22. The leaf spring 20 is configured to press the balancing valve 11 onto the valve plate 22. The upper end of the balancing valve 11 extends upward to the top of the valve plate 22. The flow tube 5 can contact the balancing valve 11 during the downward movement, so that the valve plate 22 can be rotated to the central flow channel of the valve seat 6 through the balancing valve 11; when the connecting sleeve 17 contacts the upper joint 1, there is a gap between the lower end of the flow tube 5 and the upper end of the balancing valve 11.

[0070] In this embodiment, the leaf spring 20 is used to press the balancing valve 11 onto the valve plate 22, and after the leaf spring 20 presses the balancing valve 11 onto the valve plate 22, the upper end of the balancing valve 11 extends upward to above the valve plate 22. In this embodiment, the flow tube 5 first contacts the balancing valve 11 during the downward movement, so that the valve plate 22 rotates to the central flow passage of the valve seat 6 through the balancing valve 11.

[0071] Thirdly, it is also necessary to satisfy the following: when the flow tube 5 is in the upper limit position, that is, when the connecting sleeve 17 is in contact with the upper joint 1, there is a gap between the lower end of the flow tube 5 and the upper end of the balancing valve 11, so that the valve plate 22 can smoothly switch to the state of blocking the central flow channel of the valve seat 6.

[0072] Again, a second through hole 28 and a third through hole 29 are provided on the balancing valve 11, and the third through hole 29 is connected to the second through hole 28. When the leaf spring 20 presses the balancing valve 11 into the mounting hole on the valve plate 22, the third through hole 29 is located in the valve plate 22. During the downward movement of the flow tube 5, the balancing valve 11 can be moved downward to connect the space above the valve plate 22 and the space below the valve plate 22 through the second through hole 28 and the third through hole 29.

[0073] In this embodiment, the second through hole 28 and the third through hole 29 are provided on the balancing valve 11. After the leaf spring 20 presses the balancing valve 11 into the corresponding mounting hole on the valve plate 22, the third through hole 29 of the balancing valve 11 is located in the mounting hole on the valve plate 22. At this time, the upper part of the leaf plate and the lower part of the valve plate 22 are not connected, that is, the valve plate 22 is in a state where the central flow channel is blocked; as the flow pipe 5 moves downward, the flow pipe 5 contacts the balancing valve 11 and presses the balancing valve 11 downward, so that the balancing valve 11 is relatively When the valve plate 22 moves downward and the balancing valve 11 moves downward to the extreme position, the third through hole 29 of the balancing valve 11 moves outside the mounting hole of the valve plate 22. At this time, the central flow channel of the valve seat 6 above the valve plate 22 and the space below the valve plate 22 are connected through the second through hole 28 and the third through hole 29. The flow tube 5 continues to move downward to push the valve plate 22 open, that is, the valve plate 22 is switched to a state of not blocking the central flow channel of the valve seat 6, thereby connecting the central flow channel of the valve seat 6 with the space below the valve plate 22.

[0074] As the flow tube 5 moves upward with the connecting sleeve 17, after the flow tube 5 moves to a point where it is no longer in contact with the upper end of the balancing valve 11, the balancing valve 11 is reset to the mounting hole of the third through hole 29 on the valve plate 22 under the action of the leaf spring 20, and the valve plate 22 is reset to the central flow channel of the blocked valve seat 6 under the action of the torsion spring.

[0075] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0076] In addition, the terms "one", "two", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0077] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A downhole safety valve, characterized in that: It comprises an upper joint and a lower joint, wherein the outer side of the lower end of the upper joint is fixedly connected to an outer connection tube, a flow tube is arranged in the central flow channel of the upper joint, and the outer lower end of the outer connection tube is fixedly connected to the lower joint; The upper joint is provided with a first through hole which runs from top to bottom, a piston rod is arranged in the first through hole, a sealing structure is sleeved on the piston rod, the sealing structure is used to seal the annulus between the piston rod and the first through hole, a connecting sleeve is fixedly connected to the lower end of the piston rod, the connecting sleeve is located between the outer connecting tube and the flow pipe, and the connecting sleeve cooperates with the flow pipe so that the flow pipe can move with the connecting sleeve; A first reset structure is provided between the outer connection tube and the flow tube below the connection sleeve, the lower end of the first reset structure is limited by the outer connection tube, and the first reset structure is configured to enable the connection sleeve to contact the upper joint; The lower end of the external connecting tube is connected to a valve body assembly, and the valve body assembly is located in the lower joint. The valve body assembly has a first state of blocking the central flow channel of the external connecting tube, and a second state of not blocking the central flow channel of the external connecting tube. The valve body assembly is in the first state under normal conditions, and the downward movement of the flow tube can switch the valve body assembly from the first state to the second state.

2. The downhole safety valve according to claim 1, characterized in that: The piston rod is provided with a first retaining ring, the sealing structure comprises a first sealing member sleeved on the piston rod above the first retaining ring, and the first sealing member is sealingly connected to the first through hole; An upper piston cap is fixedly connected to the upper end of the piston rod, and a first spring is arranged between the upper piston cap and the first sealing member, and the first spring is configured to press the first sealing member onto the first retaining ring.

3. The downhole safety valve according to claim 2, characterized in that: The sealing structure further comprises a second sealing member sleeved on the piston rod below the first retaining ring, wherein the second sealing member is sealingly connected to the first through hole; The sealing surface between the first baffle ring and the first seal and the sealing surface between the first baffle ring and the second seal intersect; or, the sealing surface between the first baffle ring and the first seal and the sealing surface between the first baffle ring and the second seal are both perpendicular to the axis of the piston rod.

4. The downhole safety valve according to claim 3, characterized in that: The first seal and the second seal are both metal parts; the first seal and the second seal both have a head and an ear, the head respectively cooperates with the corresponding sides of the first retaining ring, the two heads are in contact with each other, and each of the heads is sleeved on the piston rod, the two ears extend in directions away from each other, and each of the ears is in contact with the inner wall of the first through hole; a wear-resistant ring is sleeved on the piston rod below the second seal.

5. The downhole safety valve according to claim 1, characterized in that: The lower end of the upper joint is fixedly connected with a stop plug, the lower end of the piston rod is fixedly connected with a lower piston cap, the lower piston cap is fixedly connected to the connecting sleeve, and the first reset structure is configured to enable the lower piston cap to be in sealing contact with the stop plug.

6. The downhole safety valve according to claim 1, characterized in that: A second retaining ring is fixedly provided on the inner side of the connecting sleeve, and a matching step is fixedly provided on the outer side wall of the flow tube, and the matching step is located below the second retaining ring. When the connecting sleeve moves downward, the matching between the second retaining ring and the matching step drives the flow tube to move downward; The connecting sleeve below the matching step is fixedly connected with a retaining spring, and the connecting sleeve moves upwards, and the matching between the retaining spring and the matching step drives the flow tube to move upwards.

7. The downhole safety valve according to claim 1, characterized in that: The first reset structure is a second spring; a first limiting ring is arranged on the inner side wall of the lower part of the outer connecting tube, a third retaining ring is arranged in the flow tube above the first limiting ring, the third retaining ring is fixedly connected with a spring retaining ring, the lower end of the second spring is limited by the spring retaining ring, the upper end surface of the spring retaining ring is a first plane, and the lower end surface of the second spring is a second plane that fits with the first plane.

8. The downhole safety valve according to claim 1, characterized in that: The valve body assembly includes a valve seat and a valve plate, wherein the valve seat is located in the lower joint, the valve seat is fixedly connected to the lower end of the external connection cylinder, the valve seat is rotatably connected to the valve plate, and a second reset structure is provided between the valve seat and the valve plate, and the second reset structure is configured to enable the valve plate to block the central flow channel of the valve seat; The flow tube cooperates with the valve plate so that when the connecting sleeve contacts the upper joint, the valve plate blocks the central flow channel of the valve seat under the action of the second reset structure, so that the flow tube can contact the valve plate during the downward movement to drive the valve plate to rotate until the central flow channel of the valve seat is not blocked; When the valve plate blocks the central flow channel of the valve seat, the valve body assembly is in a first state, and when the valve plate does not block the central flow channel of the valve seat, the valve body assembly is in a second state.

9. The downhole safety valve according to claim 8, characterized in that: A leaf spring is fixedly connected to the lower side of the valve plate, and a balancing valve is arranged on the valve plate. The leaf spring is configured to press the balancing valve onto the valve plate. The upper end of the balancing valve extends upward to above the valve plate. The flow tube can contact the balancing valve during the downward movement, so that the valve plate can be rotated through the balancing valve to not block the central flow channel of the valve seat; when the connecting sleeve contacts the upper joint, a gap is provided between the lower end of the flow tube and the upper end of the balancing valve.

10. The downhole safety valve according to claim 9, characterized in that: The balancing valve is provided with a second through hole and a third through hole, and the third through hole is connected to the second through hole. When the leaf spring presses the balancing valve into the mounting hole on the valve plate, the third through hole is located in the valve plate, and the balancing valve can be moved downward during the downward movement of the flow tube to connect the space above the valve plate and the space below the valve plate through the second through hole and the third through hole.

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