Check valve for closed gas lift and plugging tool of check valve

Abstract

The invention provides a check valve for closed gas lift. The check valve comprises an outer cylinder used for being communicated with a tubular column and a one-way conduction mechanism arranged in the outer cylinder. Wherein the one-way conducting mechanism comprises a ball seat arranged in the outer cylinder in a sealing manner, a salvage part located on the same axis with the ball seat and detachably connected with the ball seat, and a plugging ball arranged between the ball seat and the salvage part, and when the plugging ball abuts against the salvage part, the salvage part is allowed to be communicated with the ball seat. In the arrangement mode, the fluid can flow upwards in one direction. In addition, the ball seat and the salvage part are located on the same axis, so that a salvage tool can be put in from the wellhead position to salvage the salvage part. By means of the mode, the problems that in the prior art, a valve element cannot be fished from the wellhead position, and later wellbore treatment and maintenance are affected are solved.

Description

Technical Field

[0001] This invention belongs to the field of closed-loop gas lift technology, and particularly relates to a single-flow valve for closed-loop gas lift and its sealing tool. Background Technology

[0002] Gas lift is a technique used in the mid-to-late stages of gas field development when the energy of the gas well itself is insufficient to achieve continuous self-flowing liquid discharge. High-pressure gas (such as natural gas or nitrogen) is injected into the gas well from the surface, increasing the gas-liquid ratio above the injection point and reducing the pressure gradient, thereby establishing a larger production pressure differential. This allows gas and liquid to continuously flow from the formation to the bottom of the well, thus restoring production in water-flooded gas wells.

[0003] Gas lift can be classified into open gas lift, semi-closed gas lift, and closed gas lift, depending on the configuration of the downhole tubing. Among them, the closed gas lift process has a check valve installed at the bottom of the tubing. As a key component of the closed gas lift tubing, the check valve must simultaneously meet the requirements of sealing, single flow, and easy retrieval during the gas lift and production processes.

[0004] However, in the existing technology, the valve core and valve body of the single-flow valve are not set on the same axis, which leads to the problem that the valve core cannot be retrieved from the wellhead position, affecting the subsequent wellbore treatment and maintenance. Summary of the Invention

[0005] To overcome at least one or more of the aforementioned defects in the prior art, a first aspect of the present invention provides a one-way valve for closed-loop gas lift, comprising an outer cylinder for communicating with a tubing string, and a one-way conduction mechanism disposed within the outer cylinder.

[0006] The unidirectional conduction mechanism includes a ball seat sealed inside the outer cylinder, a retrieval part coaxial with the ball seat and detachably connected to it, and a sealing ball disposed between the ball seat and the retrieval part.

[0007] The ball seat is provided with a sealed limiting part for receiving the blocking ball, and the retrieval part is provided with an elastic element. The limiting part and the elastic element together form a space for the movement of the blocking ball, and the elastic element undergoes elastic deformation when subjected to an upward force applied by the blocking ball, allowing the retrieval part to connect with the ball seat.

[0008] In one embodiment, the retrieval part includes a retrieval part body that allows the blocking ball to pass through, and the elastic element is configured as a plurality of elastic sheets distributed circumferentially along the end face of the retrieval part body, all of which are inclined toward the axis of the retrieval part.

[0009] In one embodiment, at least one third through hole is provided on the outer cylinder, and a shear pin is provided in the third through hole. The ball seat is provided with a groove adapted to the shear pin. The shear pin is disposed in the groove for limiting the ball seat. The shear pin is configured to disengage from the ball seat, thereby allowing the ball seat to move inside the outer cylinder.

[0010] In one embodiment, at least one first through hole penetrating the side wall of the outer cylinder is provided on the outer cylinder, and at least one second through hole penetrating the side wall of the retrieval part is provided on the retrieval part. The retrieval part is configured to move downward together with the ball seat and allow the first through hole and the second through hole to communicate with each other.

[0011] In one embodiment, a first groove is provided on the inner wall of the outer cylinder, and a second groove is provided on the ball seat. A deformation part is provided in the second groove. When the first groove and the second groove are configured to correspond, the deformation part restores elastic deformation, limits the ball seat, and makes the first through hole and the second through hole communicate with each other.

[0012] In one embodiment, at least one limiting pin is provided on the outer cylinder, and an inwardly recessed sliding groove is provided on the ball seat. The limiting pin extends into the sliding groove to form a space for axial movement of the ball seat together with the sliding groove, and allows the first through hole to communicate with the second through hole when the limiting pin abuts against the upper end face of the sliding groove.

[0013] In one embodiment, a connecting assembly is provided at the free end of the retrieval unit body. The connecting assembly includes a connecting sleeve disposed along the end face of the retrieval unit body and a protruding rib disposed on the connecting sleeve. The one-way valve also includes an upper connector for connecting the tubing and the outer cylinder. The upper connector includes a locking part that abuts against the ball seat and is used to limit the protruding rib. When the protruding rib and the locking part are configured to contact each other, the first through hole and the second through hole are allowed to communicate with each other.

[0014] In one embodiment, a meshing portion is also provided on the rib, the outer diameter of which gradually decreases from the connecting end to the free end, and ratchet teeth are formed on the meshing portion for meshing with the retrieval tool.

[0015] In one embodiment, the ball seat and the retrieval part are connected to each other by a pin, the pin being configured to disengage from the ball seat when the engagement part is subjected to a force applied by the retrieval tool.

[0016] According to a second aspect of the present invention, a plugging tool is provided for plugging the aforementioned check valve.

[0017] The sealing tool includes a sealing plug disposed within the ball seat, and a hook-on portion disposed on the sealing plug and extending downward for engaging with the end of the ball seat.

[0018] The sealing plug includes a sealing head that mates with the limiting part, and a sealing cylinder disposed on the sealing head for disconnecting the internal and external phases of the check valve.

[0019] The latching part includes an elastic piece that is connected to the sealing head and extends downward, and a barb disposed at the end of the elastic piece for engaging with the end of the ball seat.

[0020] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0021] This invention features an outer cylinder for connection to the tubing string, within which a unidirectional flow mechanism is installed. This unidirectional flow mechanism comprises a ball seat and a detachably connected retrieval section coaxial with the ball seat, allowing the retrieval section and ball seat to form a fluid passage. Simultaneously, a limiting part for sealing and receiving the plugging ball is provided within the ball seat, and an elastic element is installed on the retrieval section. The limiting part and the elastic element together create space for the plugging ball's movement, and the elastic element undergoes elastic deformation when subjected to an upward force applied by the plugging ball, allowing the retrieval section to connect with the ball seat. This configuration allows for unidirectional upward fluid flow. Furthermore, by positioning the ball seat and retrieval section coaxially, a retrieval tool can be lowered from the wellhead to retrieve the retrieval section. This method solves the problem in existing technologies where valve cores cannot be retrieved from the wellhead, affecting subsequent wellbore processing and maintenance. Attached Figure Description

[0022] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0023] Figure 1 The schematic diagram shows the overall structure of the single-flow valve for closed-loop gas lift according to the present invention in its normal state;

[0024] Figure 2 The schematic diagram shows the overall structure of the single-flow valve in the air-lift state for closed-loop air lift according to the present invention;

[0025] Figure 3 The schematic diagram shows the overall structure of the single-flow valve for closed-loop air lift in the retrieval state according to the present invention;

[0026] Figure 4 The schematic diagram shows the overall structure of the single-flow valve for closed-loop gas lift according to the present invention in the plugged state;

[0027] Figure 5 The schematic diagram shows the overall structure of the unidirectional conduction mechanism of the one-way valve for closed-loop gas lift according to the present invention.

[0028] Figure 6 The schematic diagram shows the overall structure of a plugging tool for a one-way valve for closed-loop air lift according to the present invention;

[0029] Figure 7 The schematic diagram illustrates the overall structure of the single-flow valve and tubing assembly for closed-loop gas lift according to the present invention.

[0030] Figure 8 The schematic diagram illustrates the overall structure of the limiting pin and sliding groove for closed air lift according to the present invention.

[0031] It should be noted that the accompanying drawings are not necessarily drawn to scale.

[0032] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 10-plugging tool; 101-plugging plug; 1011-plugging head; 1012-plugging cylinder; 102-hooking part; 1021-elastic sheet; 1022-barrel claw; 103-connecting joint; 20-tube string; 100-one-flow valve for closed-loop gas lift; 1-upper joint; 11-connecting part; 12-first fixing part; 13-locking part; 2-outer cylinder; 21-first through hole; 22-first groove; 23-third through hole; 24-limiting pin; 3-single Guide mechanism; 31-ball seat; 311-ball seat body; 312-limiting part; 313-pin; 314-second groove; 315-slot; 316-sealing groove; 317-sliding groove; 3171-sliding part; 3172-retracting part; 32-retrieval part; 321-retrieval part body; 322-elastic element; 323-second through hole; 33-connecting assembly; 331-connecting sleeve; 332-protruding rib; 333-engaging part; 4-blocking ball; 5-lower connector; 51-liquid inlet; 52-second fixing part; 53-abutment part. Detailed Implementation

[0033] To better understand the purpose, structure, and function of this invention, a single-flow valve for closed-loop air lift will be described in further detail below with reference to the accompanying drawings.

[0034] For convenience, the direction of movement from the lower connector to the upper connector will be referred to as "upward movement" or similar terminology, and the direction of movement from the upper connector to the lower connector will be referred to as "downward movement" or similar terminology.

[0035] like Figure 1 As shown, one embodiment of the present invention provides a one-way valve 100 for closed-loop air lift, including an upper connector 1 and an outer cylinder 2 that are interconnected and together form a fluid movement path. The upper connector 1 and the outer cylinder 2 are configured in any shape to facilitate fluid movement. In this embodiment, both the upper connector 1 and the outer cylinder 2 are configured as hollow circular tubular structures.

[0036] In one embodiment, such as Figure 1 As shown, the upper connector 1 includes a connecting portion 11 for communicating with a tubular column (not shown in the figure), and a first fixing portion 12 disposed on the end face of the connecting portion 11. Meanwhile, a recessed boss is formed on the inner wall of the outer cylinder 2. In this embodiment, the outer diameter of the first fixing portion 12 is configured to be approximately equal to the inner diameter of the boss inside the outer cylinder 2. Simultaneously, the axial length of the first fixing portion 12 is adapted to the axial length of the boss. In this way, the connecting portion 11, the first fixing portion 12, and the outer cylinder 2 can abut against each other.

[0037] According to a preferred embodiment of the present invention, the first fixing part 12 is provided with an external thread, and the inner side of the inner boss of the outer cylinder 2 is provided with an internal thread adapted to the external thread. In this way, the first fixing part 12 can be connected to the outer cylinder 2 as a whole, thereby allowing the upper connector 1 to be detachably connected to the outer cylinder 2.

[0038] In one embodiment, such as Figure 1 As shown, a one-way conduction mechanism 3 is provided inside the outer cylinder 2. The one-way conduction mechanism 3 includes a hollow ball seat 31 that is detachably disposed inside the outer cylinder 2, and a retrieval part 32 disposed inside the ball seat 31 in cooperation with the ball seat 31. At the same time, both the ball seat 31 and the retrieval part 32 form a hollow circular tubular structure.

[0039] Among them, such as Figure 5 As shown, the ball seat 31 includes a ball seat body 311 and a limiting part 312 disposed inside the body. The limiting part 312 is constructed as a hollow frustum, which is configured to receive and seal the ball 4 in a sealed manner.

[0040] Meanwhile, the salvage unit 32 includes a salvage unit body 321 and an elastic member 322 disposed on the end face of the salvage unit body 321 near the limiting part 312. The elastic member 322 is disposed circumferentially along the end face of the salvage unit body 321. Furthermore, the elastic member 322 is inclined toward the axis of the salvage unit body 321. In this embodiment, the elastic member 322 is made of any elastic sheet capable of elastic deformation.

[0041] In one embodiment, such as Figure 2 As shown, the one-way valve 100 also includes a sealing ball 4 disposed between the elastic member 322 and the limiting portion 312, the diameter of which is larger than that of the limiting portion 312. In this embodiment, the hollow frustum formed by the limiting portion 312 is configured to fit the contour of the sealing ball 4. In this way, when the sealing ball 4 is in contact with the limiting portion 312, the sealing ball 4 can block the channel, thereby disconnecting the fluid flow path.

[0042] In this configuration, when the blocking ball 4 is subjected to a downward force, it will continue to move downward until it comes into contact with the limiting part 312. At this point, because the diameter of the blocking ball 4 is larger than that of the limiting part 312, and the limiting part 312 is configured to fit the contour of the blocking ball 4, the blocking ball 4 can fit tightly against the limiting part 312 under pressure. This blocks the fluid flow path, closing the top-to-bottom movement channel.

[0043] However, when the blocking ball 4 is subjected to an upward force, it will continue to move upward. At this time, the blocking ball 4 will move away from the limiting part 312, creating a gap between the blocking ball 4 and the limiting part 312 for fluid passage. Simultaneously, the blocking ball 4, under the applied force, can compress the elastic element 322, causing it to undergo elastic deformation.

[0044] This increases the fluid flow path. In this way, the retrieval section 32, the sealing ball 4, and the ball seat 31 together form a one-way flow mechanism 3. Specifically, in this configuration, the one-way valve 100 blocks from top to bottom and flows from bottom to top. Furthermore, in this embodiment, the ball seat 31 and the retrieval section 32 are positioned on the same axis, facilitating the insertion of retrieval tools along the tubing from the wellhead for retrieval of the retrieval section 32.

[0045] In this configuration, during use, the sealing ball 4 is placed inside the tubing, and a downward force is applied to the sealing ball 4 located inside the tubing, so that the sealing ball 4 can move downward along the channel formed by the tubing, the upper connector 1, and the retrieval part 32.

[0046] When the blocking ball 4 moves to the free end of the retrieval section 32 and comes into contact with the elastic element 322, the blocking ball 4 will exert a circumferential force on the elastic element 322 and compress the elastic element 322, causing the elastic element 322 to undergo elastic deformation along the circumferential direction. At this time, the elastic element 322 will expand, thereby causing the diameter formed by the elastic element 322 to expand.

[0047] This allows the blocking ball 4 to pass through the elastic member 322 and be positioned between the elastic member 322 and the limiting part 312. At this point, the elastic member 322 will restore its elastic deformation, thereby preventing the blocking ball 4 from moving upward. As the downward force continues to be applied, the blocking ball 4 will continue to move downward until it comes into contact with the limiting part 312.

[0048] In this way, the one-way valve 100 can be selectively made to conduct in one direction. In this configuration, when the gas pressure inside the gas well is sufficient to achieve continuous self-flowing liquid discharge, the plugging ball 4 is not lowered. When the gas pressure inside the gas well is insufficient to achieve continuous self-flowing liquid discharge, the plugging ball 4 can be lowered from the tubing string to perform gas lift. Thus, the one-way valve 100 has two states: a normal state and a gas lift state.

[0049] In one embodiment, such as Figure 1 As shown, the outer cylinder 2 has at least one third through hole 23, and a shear pin (not shown in the figure) is disposed in the third through hole 23. Meanwhile, as... Figure 5 As shown, the ball seat 31 is provided with a groove 315 that matches the shear pin. In this way, the outer cylinder 2 and the ball seat 31 can be connected as a single unit by the shear pin, allowing the ball seat 31 to be stably positioned inside the outer cylinder 2 under normal conditions. Furthermore, the shear pin is configured to detach from the ball seat 31 in the air-lift state. With this configuration, when the one-way valve 100 is in the air-lift state, the shear pin can detach from the ball seat 31, thereby allowing the one-way conduction mechanism 3 to move downwards.

[0050] In one embodiment, such as Figure 1 As shown, the outer cylinder 2 is provided with at least one first through hole 21 penetrating the wall of the outer cylinder 2. Meanwhile, as... Figure 5 As shown, a second through hole 323 corresponding to the first through hole 21 is provided on the retrieval section 32. In this way, when the one-way valve is in the air-lift state, the first through hole 21 and the second through hole 323 can communicate with each other and jointly connect to the outside. This arrangement allows for internal and external communication between the one-way valve 100, thereby increasing the fluid flow path.

[0051] In one embodiment, such as Figure 1 As shown, a first groove 22 is formed circumferentially on the inner wall of the outer cylinder 2 near the free end. Meanwhile, as... Figure 5 As shown, a second groove 314 is formed circumferentially on the outer wall of the ball seat 31 near the free end. A deformation portion (not shown in the figure) is provided within the second groove 314. In this embodiment, the deformation portion is configured as a C-shaped ring.

[0052] In this way, under normal conditions, the ball seat 31 is positioned inside the outer cylinder 2. The two sides of the deformable portion will contact the second groove 314 and the inner wall of the outer cylinder 2, causing the deformable portion to elastically deform and position itself within the second groove 314. When the first groove 22 and the second groove 314 correspond, the deformable portion will regain its elastic deformation, with its two sides positioned within the first groove 22 and the second groove 314 respectively. This allows for a relatively fixed relationship between the ball seat 31 and the outer cylinder 2.

[0053] When the one-way valve 100 needs to be used and is in a gas-lift state, the sealing ball 4 is placed into the tubing, and a downward force is applied to the sealing ball 4 located in the tubing. At this time, the sealing ball 4 and the retrieval part 32 can move downward together. During the downward movement of the retrieval part 32, since the retrieval part 32 and the ball seat 31 are connected, the ball seat 31 will move downward synchronously with the retrieval part 32 until the second groove 314 on the ball seat 31 corresponds to the first groove 22 in the outer cylinder 2.

[0054] At this time, the deformed portion located in the second groove 314 will recover its elastic deformation, and the two sides of the deformed portion will be located in the first groove 22 and the second groove 314 respectively. As a result, the ball seat 31 and the outer cylinder 2 can be relatively fixed, so that the ball seat 31 and the retrieval part 32 are axially fixed in the outer cylinder 2 and cannot continuously move.

[0055] In this manner, the blocking ball 4 will continuously move downwards along the channel inside the retrieval section 32 until it passes through the elastic member 322 and abuts against the limiting part 312. Thus, the channel can be blocked by the blocking ball 4, making the channel sealed from top to bottom and open from bottom to top.

[0056] At this time, as the retrieval section 32 continues to move downwards, the second through hole 323 on the retrieval section 32 and the first through hole on the outer cylinder 2 will correspond to each other. This allows the first through hole 21 and the second through hole 323 to communicate with the outside. In this way, the single-flow valve 100 forms an airlift state where the inside and outside are connected, but not connected from top to bottom, and connected from bottom to top.

[0057] In one embodiment, such as Figure 1 As shown, at least one limiting pin 24 is also provided on the outer cylinder 2. Meanwhile, as... Figure 5As shown, a sliding groove 317 is provided on the ball seat 31, recessed inward along the circumferential direction. The limiting pin 24 extends inward into the sliding groove 317 and is configured to abut against both ends of the sliding groove. In this way, space is created for the axial movement of the ball seat 32, allowing the ball seat 32 to move axially within the length of the sliding groove 317.

[0058] In this embodiment, the sliding groove 317 is configured such that when the limiting pin 24 contacts the upper end face of the sliding groove 317, the first through hole 21 and the second through hole 323 are connected. This configuration limits the axial movement distance of the ball seat 31, thereby preventing the ball seat 31 from detaching from the outer cylinder 2. This allows the ball seat 31 to be more stably positioned within the outer cylinder 2.

[0059] According to a preferred embodiment of the present invention, such as Figure 8 As shown, the sliding groove 317 includes a sliding portion 3171 that forms the movement path of the limiting pin 24, and a retracting portion 3172 for accommodating the limiting pin 24, thereby limiting the movement of the ball seat 31. In this embodiment, the retracting portion 3172 is disposed on one side of the sliding portion 3171 and forms a bend with the sliding portion 3171. Specifically, the sliding portion 3171 and the retracting portion 3172 together form a "J"-shaped structure, allowing the first through hole 21 and the second through hole 323 to communicate with each other when the limiting pin 24 is located in the retracting portion 3172.

[0060] In this configuration, when the ball seat 31 moves downward, the limiting pin 24 can move along the path formed by the sliding part 3171 into the retracting part 3172 and abut against the free end of the retracting part 3172, thereby limiting the downward movement of the ball seat 31. However, when the ball seat 31 moves upward, as the ball seat 31 continues to move upward, the limiting pin 24 will abut against the bend of the retracting part 3172, thereby limiting the upward movement of the ball seat 31. In this way, the ball seat 31 is further stably positioned inside the outer cylinder 2. It should be noted that when the limiting pin 24 abuts against the bend 3172, the first through hole 21 and the second through hole 323 remain connected.

[0061] In one embodiment, such as Figure 1 As shown, the upper connector 1 also includes a locking part 13 disposed on the first fixing part 12 and extending along the axial direction of the first fixing part 12. The locking part 13 is configured as a circular tubular structure with an inner diameter smaller than that of the first fixing part 12 and abuts against the outer cylinder 2.

[0062] At the same time, such as Figure 5As shown, a connecting component 33 is also provided at the free end of the retrieval part body 321. In this embodiment, the connecting component 33 includes a connecting sleeve 331 that is provided along the end face of the retrieval part body 321 and extends toward the side away from the ball seat 31, and a protruding rib 332 that is provided at the free end of the connecting sleeve 331 and extends outward in a circumferential direction. The protruding rib 332 is configured to be of any shape that can abut against the engaging part 13.

[0063] In this way, when the protruding rib 332 comes into contact with the engaging part 13, the engaging part 13 can axially limit the unidirectional conduction mechanism 3 through the protruding rib 332, thereby preventing the unidirectional conduction mechanism 3 from moving downward when subjected to a downward force. This further ensures that the unidirectional conduction mechanism 3 is stably positioned inside the outer cylinder 2.

[0064] In one embodiment, such as Figure 5 As shown, the free end of the rib 332 is further provided with an engaging portion 333, which extends away from the ball seat 31, and the outer diameter of the engaging portion 333 gradually decreases from the connecting end to the free end. Simultaneously, ratchet teeth are formed on the end face of the engaging portion 333 for engaging with a retrieval tool (not shown). In this way, the retrieval tool can engage with the engaging portion 333 along the inclined path formed by the engaging portion 333, thereby retrieving the retrieval unit 32.

[0065] According to a preferred embodiment of the present invention, the engaging portion 333 is made of a material capable of elastic deformation. In this way, when the engaging portion 333 comes into contact with the retrieval tool, the retrieval tool can force the engaging portion 333 to undergo circumferential elastic deformation, causing the engaging portion 333 to contract circumferentially inward and recover its elastic deformation after being positioned behind the retrieval tool, thereby forming a stable fit between the engaging portion 333 and the retrieval tool. However, it should be noted that the connecting sleeve 331 can also be made of any material with elastic deformation properties.

[0066] In one embodiment, such as Figure 5 As shown, a pin 313 is provided on the ball seat 31, the pin 313 penetrating through the side wall of the ball seat 31 and extending inward. The retrieval part 32 is provided with a pin hole (not shown in the figure) adapted to the pin 313. In this way, the ball seat 31 and the retrieval part 32 are detachably connected as one unit. At the same time, the pin 313 is configured to disengage from the ball seat 31 when the engaging part 333 is subjected to a force applied by the retrieval tool. In this way, the retrieval tool can retrieve the retrieval part 32 to the outside.

[0067] According to a preferred embodiment of the present invention, such as Figure 2As shown, sealing grooves 316 for placing sealing rings are provided circumferentially at both ends of the ball seat 31 and on the engaging part 13, and sealing rings are provided in each sealing groove 316. In this way, the airtightness between the ball seat 31 and the upper connector 1 and the outer cylinder 2 can be increased.

[0068] According to a preferred embodiment of the present invention, such as Figure 1 As shown, the one-way valve 100 further includes a lower connector 5 disposed at the end of the outer cylinder 2 and connected to the outer cylinder 2. The lower connector 2 includes a liquid inlet 51 with an outer diameter equivalent to that of the outer cylinder 2, and a second fixing part 52 disposed on the liquid inlet 51 and extending toward the inside of the outer cylinder 2. In this configuration, the lower connector 5 and the outer cylinder 2 can be connected as a single unit by the second fixing part 52. At the same time, the second fixing part 52 extending inside the outer cylinder 2 can also abut against the ball seat 31, thereby further limiting the movement of the ball seat.

[0069] According to a preferred embodiment of the present invention, such as Figure 1 As shown, the second fixing part 52 is provided with an abutment part 53 extending towards the inner cylinder 2. The abutment part 53 is used to limit the ball seat 31, thereby making the ball seat 31 stably set inside the outer cylinder 2. At the same time, in this arrangement, the second through hole 323 on the retrieval part 32 and the first through hole 21 on the outer cylinder 2 correspond to each other. Thus, the first through hole 21 and the second through hole 323 can communicate with the outside. In this way, the one-way valve 100 is connected to the outside.

[0070] According to a preferred embodiment of the present invention, the second fixing part 52 and the outer cylinder 2 are respectively provided with corresponding mating threads. In this way, the lower connector 5 can be detachably connected to the outer cylinder 2.

[0071] According to a preferred embodiment of the present invention, such as Figure 2 As shown, the abutment portion 53 has a sealing groove 316 for placing a sealing ring, and the sealing groove 316 contains the sealing ring. In this way, the airtightness between the outer cylinder 2 and the lower connector 5 can be increased.

[0072] The operation of the one-way valve 100 for closed-loop air lift according to the present invention is as follows.

[0073] First, such as Figure 2 As shown, each sealing ring is placed in its corresponding sealing groove 316, and the upper connector 1, outer cylinder 2, and lower connector 5 are sequentially connected to each other. Simultaneously, the upper connector 1 is connected to the tubing (not shown in the figure). In this way, a passage for fluid movement is formed.

[0074] Next, the ball seat 31 is placed inside the outer cylinder 2, and the ball seat 31 is adjusted so that the groove 315 on the ball seat 31 corresponds to the third through hole 23 on the outer cylinder 2. Simultaneously, a shear pin is installed inside the third through hole 23. In this way, the ball seat 31 is connected to the outer cylinder 2. At this time, the two sides of the deformable portion on the ball seat 31 will contact the second groove 314 and the inner wall of the outer cylinder 2, causing the deformable portion to elastically deform and reside within the second groove 314.

[0075] Next, the retrieval part 31 is placed inside the connecting end of the ball seat 32, and the ball seat 31 and the retrieval part 32 are connected as one unit by the pin 313. Simultaneously, the protruding rib 332 on the retrieval part 31 is positioned above the engaging part 13. In this configuration, the first through hole 21 on the outer cylinder 2 corresponds to the ball seat 31. At this time, the one-way valve 100 will be vertically connected but not internally connected. In this configuration, the one-way valve is in its normal state, and the fluid can move upward along the passage formed by the aforementioned components.

[0076] When the pressure below the check valve 100 is insufficient to drive the fluid to move continuously upward, an air lift operation is required to put the check valve into an air lift state, thereby enabling the fluid to move continuously upward. At this time, the sealing ball 4 is placed in the tubing, and a downward force is applied to the sealing ball 4 located in the tubing, so that the sealing ball 4 can move continuously along the passage, pass through the retrieval part 32, and reach the space between the retrieval part 32 and the ball seat 31, thus sealing the passage.

[0077] As the aforementioned force continues to be applied, it is transmitted to the retrieval part 32, thereby driving it to move downwards. At this time, the retrieval part 32 will also cause the ball seat 31 to move downwards until the end of the ball seat 32 abuts against the lower connector 5. At this point, the first groove 22 on the outer cylinder 2 and the second groove 314 on the ball seat 31 correspond, causing the deformed portion within the second groove 314 to regain its elastic deformation, and causing both sides of the deformed portion to be located within the first groove 22 and the second groove 314 respectively, thereby locking the ball seat 31.

[0078] Simultaneously, the limiting pin 24 on the outer cylinder 2 abuts against the upper end face of the sliding groove 317, and the protruding rib 332 on the connecting assembly 33 also abuts against the engaging part 13. At this time, the ball seat 31 and the retrieval part 32 will be stably set inside the outer cylinder 2. In this arrangement, the first through hole 21 on the outer cylinder 2 and the second through hole 323 on the ball seat 32 can communicate with the outside. In this way, the one-way valve 100 is connected inside and outside, not connected from top to bottom, and connected from bottom to top.

[0079] Then, high pressure is applied at the wellhead towards the well. This high pressure then moves downwards along the well's pathway, exerting an upward force on the fluid inside, preventing it from moving downwards. This completes the gas lift operation.

[0080] After the airlift is completed, when it is necessary to retrieve the retrieval part 32, the retrieval tool (not shown in the figure) is connected to the engagement part 333 located at the inlet end of the connecting assembly 33, and a force is applied to the engagement part 333 by the retrieval tool, causing the ball seat 31 to disengage from the retrieval part 32, thereby retrieving the retrieval part 32 to the outside. At this time, the sealing ball 4 can move upward with the fluid, or it can be retrieved by the corresponding retrieval tool. Thus, the retrieval work is completed.

[0081] In one embodiment, such as Figure 7 As shown, the present invention also provides a plugging tool 10 for sealing the check valve 100. The plugging tool 10 is used to block the path of fluid movement formed by the check valve 100, thereby replacing the tubing 20 located above the check valve 100. However, the tubing 20 is a structure known to those skilled in the art, and therefore will not be described in detail here.

[0082] In this embodiment, as Figure 6 As shown, the sealing tool 10 includes a sealing plug 101 that seals against the inner wall of the ball seat 31, and a latching portion 102 disposed on the sealing plug 101 and extending toward the lower connector 5. The latching portion 102 is configured to pass through the ball seat 31 and engage with the end face of the ball seat 31 near the lower connector 5. In this way, the sealing tool 10 can be stably positioned within the ball seat 31 and seal the channel formed by the ball seat 31.

[0083] In this invention, such as Figure 6 As shown, the sealing plug 101 includes a sealing head 1011, which is configured as a frustum shape to fit the limiting part 312. In this way, when the sealing plug 101 is subjected to a downward force, it can fit tightly against the limiting part 312, thereby sealing the vertically connected channel formed by the ball seat 32.

[0084] At the same time, such as Figure 6 As shown, the sealing plug 101 further includes a sealing cylinder 1012 connected to the sealing head 1011 and extending upward, the sealing cylinder 1012 being configured to fit against the inner wall of the ball seat 31. Preferably, in this embodiment, a plurality of sealing rings are arranged around the sealing cylinder 1012. In this way, the sealing cylinder 1012 can seal the internal and external channels formed by the one-way valve 100.

[0085] In one embodiment, such as Figure 6 As shown, the latching part 102 includes an elastic piece 1021 that is connected to the sealing head 1011 and extends downward, and a barb 1022 disposed at the end of the elastic piece 1021 for engaging with the lower end face of the ball seat 31. In this way, the sealing tool 10 can be stably disposed in the ball seat 31 and seal the ball seat 31.

[0086] The elastic plate 1021 is capable of elastic deformation, and the cross-section of the free end of the barb 1022 is triangular. This allows the barb 1022 to be easily inserted into the ball seat 31. The deformation of the elastic plate 1021 allows the sealing tool to continuously move downwards until the barb 1022 penetrates the channel formed by the ball seat 31. The elastic plate 1021 then recovers its elastic deformation, causing the barb 1022 to engage with the lower end face of the ball seat 31.

[0087] According to a preferred embodiment of the present invention, such as Figure 6 As shown, the sealing tool 10 also includes a connecting joint 103 disposed at the free end of the sealing cylinder 1012. The connecting joint 103 is configured in any way to facilitate connection with a conveying mechanism (not shown in the figure). In this way, the conveying mechanism can connect to the connecting joint 103 and convey the sealing tool 10 into the ball seat 31, thereby sealing the ball seat 31.

[0088] In this embodiment, as Figure 6 As shown, the connecting joint 103 and the sealing cylinder 1012 are connected by a pin. The pin is configured to allow the sealing cylinder 1012 to disengage from the connecting joint 103 when subjected to the force of the conveying mechanism, thereby facilitating the removal of the conveying mechanism.

[0089] In this configuration, when the ball seat 31 needs to be blocked to replace the tubing string 20, the connecting joint 103 is connected to the conveying mechanism, which moves along the path formed by the upper joint, thereby conveying the blocking tool 10 into the ball seat 31. The blocking tool 10 then blocks the channel formed by the check valve 100. Simultaneously, after blocking, the conveying mechanism applies force to the connecting joint 103, causing it to connect with the blocking cylinder 1012, and then the connecting joint 103 is removed. This completes the blocking of the channel formed by the check valve 100, allowing for the replacement of the tubing string 20.

[0090] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A one-way valve for closed-loop air lift, characterized in that, It includes an outer cylinder (2) for communicating with the tubing column, and a unidirectional conduction mechanism (3) disposed within the outer cylinder (2). The unidirectional conduction mechanism (3) includes a ball seat (31) sealed inside the outer cylinder (2), a retrieval part (32) located on the same axis as the ball seat (31) and detachably connected to it, and a blocking ball (4) disposed between the ball seat (31) and the retrieval part (32). The ball seat (31) is provided with a sealing limiting part (312) for receiving the blocking ball (4), and the retrieval part (32) is provided with an elastic element (322). The limiting part (312) and the elastic element (322) together form a space for the movement of the blocking ball (4), and the elastic element (322) undergoes elastic deformation when subjected to an upward force applied by the blocking ball (4), and allows the retrieval part (32) to be connected to the ball seat (31).

2. The one-way valve for closed-loop air lift according to claim 1, characterized in that, The salvage section (32) includes a salvage section body (321) that allows the blocking ball (4) to pass through. The elastic element (322) is configured as a plurality of elastic sheets distributed circumferentially along the end face of the salvage section body (321), and the plurality of elastic sheets are all inclined toward the axis of the salvage section (32).

3. The one-way valve for closed-loop air lift according to claim 2, characterized in that, At least one third through hole (23) is provided on the outer cylinder (2), and a shear pin is provided in the third through hole (23). A groove (315) adapted to the shear pin is provided on the ball seat (31). The shear pin is provided in the groove (315) for limiting the ball seat (31). The shear pin is configured to disengage from the ball seat (31), thereby allowing the ball seat (31) to move inside the outer cylinder (2).

4. The one-way valve for closed-loop air lift according to claim 3, characterized in that, At least one first through hole (21) penetrating the side wall of the outer cylinder (2) is provided on the outer cylinder (2), and at least one second through hole (323) penetrating the side wall of the retrieval part (32) is provided on the retrieval part (32). The retrieval part (32) is configured to move downward together with the ball seat (31) and allow the first through hole (21) and the second through hole (323) to communicate with each other.

5. The one-way valve for closed-loop air lift according to claim 4, characterized in that, A first groove (22) is provided on the inner wall of the outer cylinder (2), and a second groove (314) is provided on the ball seat (31). A deformation part is provided in the second groove (314). When the first groove (22) and the second groove (314) are configured to correspond, the deformation part restores elastic deformation, limits the ball seat (31), and makes the first through hole (21) and the second through hole (323) communicate with each other.

6. The one-way valve for closed-loop air lift according to claim 4, characterized in that, At least one limiting pin (24) is provided on the outer cylinder (2), and a sliding groove (317) is provided on the ball seat (31) that is recessed inward. The limiting pin (24) extends into the sliding groove (317) to form a space for the axial movement of the ball seat (32) together with the sliding groove (317), and allows the first through hole (21) and the second through hole (323) to communicate when the limiting pin (24) abuts against the upper end face of the sliding groove (317).

7. The one-way valve for closed-loop air lift according to claim 4, characterized in that, A connecting assembly (33) is also provided at the free end of the retrieval unit body (321). The connecting assembly (33) includes a connecting sleeve (331) provided along the end face of the retrieval unit body (321) and a protruding rib (332) provided on the connecting sleeve (331). The one-way valve also includes an upper connector (1) for connecting the tubing and the outer cylinder (2). The upper connector (1) includes a locking part (13) that abuts against the ball seat (31) and is used to limit the protruding rib (332). When the protruding rib (332) and the locking part (13) are configured to contact each other, the first through hole (21) and the second through hole (323) are allowed to communicate with each other.

8. The one-way valve for closed-loop air lift according to claim 7, characterized in that, A meshing part (333) is also provided on the rib (322), the outer diameter of which gradually decreases from the connecting end to the free end, and ratchet teeth are formed on the meshing part (333) for meshing with the salvage tool.

9. The one-way valve for closed-loop air lift according to claim 8, characterized in that, The ball seat (31) and the retrieval part (32) are connected to each other by a pin (313), which is configured to disengage from the ball seat (31) when the engagement part (333) is subjected to a force applied by the retrieval tool.

10. A sealing tool, characterized in that, The sealing tool is used to seal the one-way valve according to any one of claims 1 to 9. The sealing tool includes a sealing plug (101) that is capable of sealing within the ball seat (31), and a hook-on portion (102) disposed on the sealing plug (101) and extending downward to engage with the end of the ball seat (31). The sealing plug (101) includes a sealing head (1011) that cooperates with the limiting part (312), and a sealing cylinder (1012) disposed on the sealing head (1011) for disconnecting the internal and external phases of the check valve. The latching part (102) includes an elastic piece (1021) that is connected to the sealing head (1011) and extends downward, and a barb (1022) provided at the end of the elastic piece (1021) for engaging with the end of the ball seat (31).

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