Plunger for preventing accumulated liquid from reducing impact of clamping device during slipping and falling back and using method

Abstract

The invention relates to the technical field of water drainage and gas recovery of oil and gas reservoirs, in particular to a plunger capable of preventing accumulated liquid from slipping and falling back and reducing impact of a clamping device and a using method, and aims to solve the problems that the gas lift effect is reduced and the clamping device is frequently damaged due to the fact that the accumulated liquid slips and impacts the clamping device during gas lift water drainage of the plunger. The invention provides a plunger which comprises a center pipe, a piston, an upper supporting piece and a lower supporting piece. A buffering cavity is formed in the center pipe, and vent holes communicating with the buffering cavity are formed in the side wall. The upper supporting pieces and the lower supporting pieces are annularly and evenly distributed around the center pipe at intervals. After the piston moves upwards, the vent hole is opened, and the lower supporting piece is driven to push the upper supporting piece; and after the piston moves downwards, the vent hole is sealed and the lower supporting sheet is driven to move. The distance between the plunger and the inner wall of a production pipe column is optimally matched through associated movement of the upper supporting piece and the lower supporting piece, accumulated liquid slipping is reduced, the central pipe is closed in the falling-back process, gas is stored in the central pipe, the relative density and the falling-back speed of the plunger are reduced, and impact is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas reservoir drainage and gas production, and in particular to a plunger and a use method thereof for reducing the impact of a retainer when preventing accumulated liquid from slipping and falling back. Background Art

[0002] The plunger gas lift drainage gas production process is one of the main processes for stable production of gas wells. Due to the large gap between the plunger and the production string, there is a significant phenomenon of liquid slippage during the liquid lifting process, which reduces the gas lift effect. At the same time, the plunger will often damage the retainer due to its high speed and high impact force during the fall back process, and the retainer needs to be replaced frequently, affecting production efficiency. Summary of the invention

[0003] The purpose of the present invention is to provide a plunger and a method of use that can prevent the accumulated fluid from slipping and reducing the impact of the retainer when falling back, so as to solve the problem that the accumulated fluid slips and impacts the retainer during gas lifting and drainage, resulting in reduced gas lifting effect and frequent damage to the retainer.

[0004] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0005] A plunger for preventing accumulated fluid from slipping and reducing the impact of a retainer when falling back, comprises a central tube, a piston, an upper support plate and a lower support plate; a buffer cavity is arranged inside the central tube, and a vent hole connected to the buffer cavity is opened on the side wall; the piston is sleeved on the central tube and slidably connected to the central tube; the lower support plate is connected to the piston, and the upper support plate is connected to the central tube; a plurality of upper support plates and lower support plates are evenly distributed around the central tube in an annular manner and arranged at intervals; after the piston moves upward, the vent hole is opened and the lower support plate is driven to push the upper support plate, so that the upper support plate moves in a direction away from the central tube; after the piston moves downward, the vent hole is closed and the lower support plate is driven to move, so that the upper support plate moves in a direction close to the central tube.

[0006] Furthermore, the plunger that reduces the impact of the retainer when preventing the accumulated fluid from slipping and falling back also includes a connecting sleeve, which is connected to the central tube and sleeved on the piston; the connecting sleeve is in contact with the upper supporting plate and the contact surface is an inclined surface.

[0007] Furthermore, the plunger that reduces the impact of the retainer when preventing the accumulated fluid from slipping and falling back also includes a limit pin, which is inserted into the upper support plate and connected to the connecting sleeve; the upper support plate is provided with a long hole, and the limit pin is inserted into the long hole and can slide along the long hole.

[0008] Furthermore, the plunger that reduces the impact of the retainer when preventing the accumulated fluid from slipping and falling back also includes a linkage clamping ring, which is sleeved on the connecting sleeve, and the upper supporting plate and the lower supporting plate are both connected to the linkage clamping ring.

[0009] Furthermore, linkage grooves are provided on the upper supporting plate and the lower supporting plate, and the linkage clamping ring is inserted into the linkage groove and can move relative to the linkage groove along the axial direction of the central tube.

[0010] Furthermore, the plunger that prevents the accumulated fluid from slipping and reducing the impact of the retainer when falling back also includes a one-way valve group, which is sleeved on the central tube and connected to the central tube, and the one-way valve group is inserted into the connecting sleeve and connected to the connecting sleeve; the piston is inserted into the annular space surrounded by the central tube and the connecting sleeve, thereby forming an inflation chamber together with the central tube, the connecting sleeve, and the one-way valve group.

[0011] Furthermore, the one-way valve group includes a valve seat, a valve core, a spring and a support seat; the valve seat is sleeved on the center tube and connected to the center tube, and the valve seat is inserted into the connecting sleeve and connected to the connecting sleeve; an inflation hole is provided on the valve seat, the valve core and the spring are provided in the inflation hole, and the support seat is inserted into the valve seat; one end of the spring is connected to the support seat, and the other end is connected to the valve core, and is configured to apply thrust to the valve core so that the valve core blocks the inflation hole.

[0012] Furthermore, the plunger that reduces the impact of the retainer when preventing the accumulated fluid from slipping and falling back also includes a limit ring, which is sleeved on the central tube and arranged between the one-way valve group and the piston.

[0013] Furthermore, the plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping and falling back also includes a pressure cap, which is inserted into the central tube and connected to the central tube to close the buffer cavity.

[0014] Another aspect of the present invention provides a method for using a plunger that reduces the impact of a retainer when preventing the accumulated fluid from slipping off and falling back, and the method comprises the following steps:

[0015] Lifting: During the lifting process, the piston moves upward to drive the lower support plate, so that the lower support plate pushes the upper support plate away from the central pipe, thereby reducing the gap between the upper support plate and the inner wall of the production pipe string;

[0016] Falling back: During the falling back process, the piston moves down to close the vent hole, and at the same time drives the lower support plate to move down to make the upper support plate close to the center tube.

[0017] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0018] The plunger provided by the present invention for preventing the accumulated fluid from slipping and reducing the impact of the retainer when falling back comprises a central tube, a piston, an upper support plate and a lower support plate; a buffer cavity is arranged inside the central tube, and a vent hole connected to the buffer cavity is opened on the side wall; the piston is sleeved on the central tube and slidably connected to the central tube; the lower support plate is connected to the piston, and the upper support plate is connected to the central tube; a plurality of upper support plates and lower support plates are evenly distributed around the central tube in an annular shape and arranged at intervals; after the piston moves upward, the vent hole is opened and the lower support plate is driven to push the upper support plate, so that the upper support plate moves in a direction away from the central tube; after the piston moves downward, the vent hole is closed and the lower support plate is driven to move, so that the upper support plate moves in a direction close to the central tube.

[0019] The plunger provided by the present invention, which prevents the accumulated fluid from slipping and reduces the impact of the retainer when falling back, is composed of an upper support plate and a lower support plate that are evenly distributed in an annular shape and spaced apart to form a sealing ring, and the upper support plate in the sealing ring can be displaced along the radial direction of the sealing ring. When the plunger moves up and it is necessary to improve the sealing performance, the upper support plate is away from the center of the sealing ring to reduce the gap between the sealing ring and the inner wall of the production tubing, so as to achieve the best fit with the production tubing and reduce the slipping of accumulated fluid during the lifting process. When the plunger moves down, the piston closes the vent hole, and the buffer chamber is filled with gas to reduce the relative density of the plunger, reduce the falling speed, thereby reducing the impact caused by the falling of the plunger and reducing damage to the retainer.

[0020] At the same time, the upper support piece retracts when the plunger moves downward, which can reduce the wear of the production pipe string on the upper support piece and increase the service life of the plunger.

[0021] In addition, as the piston moves upward, the vent is in an open state. At this time, some liquid can enter the buffer chamber in the center tube, allowing the plunger to maintain its original density, avoiding the plunger rising too quickly and causing a decrease in liquid carrying capacity, thereby ensuring the lifting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of the structure of a plunger in a lifted state to reduce the impact of a retainer when preventing fluid accumulation from slipping off and falling back provided by an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the structure of the plunger in the state of lifting and falling back to prevent the fluid from slipping off and reducing the impact of the retainer when falling back provided by an embodiment of the present invention;

[0025] Figure 3 It is a structural schematic diagram of the upper support plate;

[0026] Figure 4 It is a structural schematic diagram of the lower support piece;

[0027] Figure 5 It is a schematic diagram of the structure of the upper supporting plate and the lower supporting plate in the falling state;

[0028] Figure 6 It is another structural schematic diagram of the upper supporting plate and the lower supporting plate in the falling state;

[0029] Figure 7 It is a structural schematic diagram of the upper supporting plate and the lower supporting plate in the lifting state;

[0030] Figure 8 It is another structural schematic diagram of the upper supporting plate and the lower supporting plate in the lifting state.

[0031] Icons: 100-center tube; 200-piston; 300-upper support plate; 400-lower support plate; 500-connecting sleeve; 600-limiting pin; 700-linking clamp; 800-one-way valve group; 900-limiting ring; 1000-pressure cap; 1100-fixing pin; 410-flanging; 810-valve seat; 820-valve core; 830-spring; 840-support seat; a-buffer chamber; b-vent; c-long hole; d-linking groove; e-inflating chamber; f-inflating hole. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0035] The currently used plunger has a large gap with the production string, and there is a significant phenomenon of fluid slippage during the fluid lifting process, resulting in a reduction in the gas lift effect. At the same time, the plunger will often damage the retainer due to its high speed and high impact during the fall back process, requiring frequent replacement of the retainer, which affects production efficiency.

[0036] In view of this, the present invention provides a plunger for preventing the accumulated fluid from slipping and reducing the impact of the retainer when falling back, comprising a central tube 100, a piston 200, an upper support plate 300 and a lower support plate 400; a buffer chamber a is arranged inside the central tube 100, and a vent b connected to the buffer chamber a is opened on the side wall; the piston 200 is sleeved on the central tube 100 and is slidably connected to the central tube 100; the lower support plate 400 is connected to the piston 200, and the upper support plate 300 is connected to the central tube 100; a plurality of upper support plates 300 and lower support plates 400 are evenly distributed in a ring around the central tube 100 and are arranged at intervals; after the piston 200 moves upward, the vent hole b is opened and the lower support plate 400 is driven to push the upper support plate 300, so that the upper support plate 300 moves away from the central tube 100; after the piston 200 moves downward, the vent hole b is closed and the lower support plate 400 is driven to move so that the upper support plate 300 moves toward the central tube 100.

[0037] The plunger provided by the present invention can prevent the fluid from slipping and reduce the impact of the retainer when falling back, and is composed of an upper support sheet 300 and a lower support sheet 400 that are evenly distributed in an annular shape and spaced apart, and the upper support sheet 300 in the sealing ring can be displaced along the radial direction of the sealing ring. When the plunger moves up and it is necessary to improve the sealing performance, the upper support sheet 300 is away from the center of the sealing ring to reduce the gap between the sealing ring and the inner wall of the production tubing, so as to achieve the best fit with the production tubing and reduce the slipping of the accumulated fluid during the lifting process. When the plunger moves down, the piston 200 closes the vent b, and the buffer chamber a is filled with gas to reduce the relative density of the plunger and reduce the falling speed, thereby reducing the impact caused by the falling of the plunger and reducing the damage to the retainer.

[0038] At the same time, the upper supporting piece 300 retracts when the plunger moves downward, which can reduce the wear of the production pipe string on the upper supporting piece 300 and increase the service life of the plunger.

[0039] In addition, as the piston 200 moves upward, the vent b is in an open state, and at this time, some liquid can enter the buffer chamber a in the central tube 100, so that the plunger maintains its original density, avoids the plunger rising too fast and causing the liquid carrying capacity to decrease, and ensures the lifting effect.

[0040] The following combination Figure 1-Figure 8 The structure and shape of the plunger provided in this embodiment for preventing the accumulated fluid from slipping off and reducing the impact of the retainer when falling back are described in detail:

[0041] In the optional solution provided in this embodiment, the plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping and falling back also includes a connecting sleeve 500 and a one-way valve group 800. Figure 1As shown, the one-way valve group 800 is sleeved on the central pipe 100 and connected to the central pipe 100, and the one-way valve group 800 is inserted into the connecting sleeve 500 and connected to the connecting sleeve 500; the connecting sleeve 500 is sleeved on the piston 200 and the connecting sleeve 500 is in contact with the upper support plate 300 and the contact surface is an inclined surface. When the upper support plate 300 moves upward relative to the connecting sleeve 500, the inclined surface contact makes the upper support plate 300 move away from the central pipe 100 to shorten the distance with the inner wall of the production pipe string, thereby reducing the slippage of the accumulated fluid.

[0042] In this embodiment, the one-way valve assembly 800 includes a valve seat 810, a valve core 820, a spring 830 and a support seat 840. Figure 1 As shown, the valve seat 810 is sleeved on the central tube 100 and is threadedly connected to the central tube 100, the valve seat 810 is inserted into the connecting sleeve 500 and is threadedly connected to the connecting sleeve 500; the valve seat 810 is provided with an inflation hole f, the valve core 820 and the spring 830 are arranged in the inflation hole f, and the support seat 840 is inserted into the valve seat 810; one end of the spring 830 is connected to the support seat 840, and the other end is connected to the valve core 820, and is configured to apply thrust to the valve core 820 so that the valve core 820 blocks the inflation hole f, thereby achieving one-way sealing. Among them, the valve core 820 is set as a ball, the inflation hole f is set as a stepped hole, and the support seat 840 is inserted into the inflation hole f and is threadedly connected to the inflation hole f.

[0043] In this embodiment, the piston 200 is inserted into the annular space surrounded by the central tube 100 and the connecting sleeve 500, thereby forming an air-filling chamber e with the central tube 100, the connecting sleeve 500, and the one-way valve assembly 800. The air-filling hole f is connected to the air-filling chamber e to communicate with the air-filling chamber e. When the air-filling chamber e is inflated, the air pressure pushes the valve core 820 to compress the spring 830, so that the air-filling hole f is opened.

[0044] In this embodiment, the two upper supporting plates 300 and the two lower supporting plates 400 are evenly distributed in a ring shape and are spaced apart. Figure 5 , Figure 6 As shown, at this time, the piston 200 does not move upward, and the upper and lower ends of the plunger can be connected through the gap between the upper support plate 300 and the inner wall of the production pipe string and the gap between the two lower support plates 400. When the plunger moves upward, the piston 200 moves upward relative to the central pipe 100 under the action of the bottom hole pressure and drives the lower support plate 400 to move upward, as shown in FIG. Figure 7 , Figure 8 As shown. Figure 4As shown, the lower support sheet 400 is provided with a flange 410, and after the flange 410 abuts against the upper support sheet 300, the upper support sheet 300 can be pushed upward, and then the upper support sheet 300 is moved away from the central pipe 100 under the action of the inclined surface of the connecting sleeve 500 to reduce the gap between the upper support sheet 300 and the inner wall of the production pipe string to prevent liquid from slipping during the lifting process. In this embodiment, only the upper support sheet 300 moves along the radial direction of the central pipe 100 to ensure the sealing performance during the lifting process, reduce liquid slipping, and at the same time ensure that sufficient gap is formed during the falling process to ensure normal falling.

[0045] In an optional solution of this embodiment, the plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping and falling back further includes a limit pin 600 and a linkage clamp ring 700. The limit pin 600 is inserted into the upper support plate 300 and connected to the connecting sleeve 500; the upper support plate 300 is provided with a long hole c, and the limit pin 600 is inserted into the long hole c and can slide along the long hole c, such as Figure 3 Specifically, the cooperation between the limiting pin 600 and the long hole c can limit the radial movement of the upper support plate 300 along the central tube 100, prevent the upper support plate 300 from falling off, and avoid the circumferential movement of the upper support plate 300, ensuring that the upper support plate 300 only moves along the radial and axial directions of the central tube 100.

[0046] The linkage snap ring 700 is sleeved on the connecting sleeve 500, and the upper supporting piece 300 and the lower supporting piece 400 are both connected to the linkage snap ring 700. Figure 3 , Figure 4 As shown, the upper supporting piece 300 and the lower supporting piece 400 are both provided with a linkage groove d, and the linkage snap ring 700 is inserted into the linkage groove d and can move relative to the linkage groove d along the axial direction of the central tube 100. After the lower supporting piece 400 moves downward, the linkage snap ring 700 can drive the upper supporting piece 300 to move downward to ensure that the upper supporting piece 300 moves in a direction close to the central tube 100, thereby preventing the upper supporting piece 300 from getting stuck and being unable to retract.

[0047] In an optional solution of this embodiment, in order to make the upper supporting piece 300 approach the central tube 100, a return spring can be provided, which is sleeved on the limit pin 600, one end of which is connected to the limit pin 600, and the other end of which is connected to the upper supporting piece 300, so as to apply a thrust to the upper supporting piece 300 so that the upper supporting piece 300 presses the connecting sleeve 500. Thus, while the lower supporting piece 400 drives the upper supporting piece 300 to move downward, the upper supporting piece 300 approaches the central tube 100 under the push of the return spring.

[0048] In the optional solution of this embodiment, the plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping and falling back further includes a limit ring 900, a pressure cap 1000 and a fixing nail 1100. The limit ring 900 is sleeved on the central tube 100 and arranged between the one-way valve group 800 and the piston 200, and is used to limit the distance that the piston 200 moves upward; the pressure cap 1000 is inserted into the central tube 100 and is threadedly connected with the central tube 100 to close the buffer chamber a. The fixing nail 1100 is inserted into the lower support plate 400 and the piston 200, and is used to fix the lower support plate 400 on the piston 200.

[0049] In the optional scheme of this embodiment, the connection method between the lower support piece 400 and the piston 200 can refer to the upper support piece 300, that is, instead of using the fixing nail 1100 for connection, the limiting nail 600 is used for connection and a long hole c is opened on the lower support piece 400, and a corresponding inclined surface is set on the connecting sleeve 500 to enable the lower support piece 400 to move away from the central pipe 100 during the upward movement. At this time, during the falling process of the plunger, the lower support piece 400 can also be retracted to reduce the friction between the lower support piece 400 and the inner wall of the production pipe string, further improving the service life of the plunger. Similarly, a reset spring can be set to apply a thrust to the lower support piece 400 so that the lower support piece 400 presses the connecting sleeve 500.

[0050] Based on the plunger provided in this embodiment that reduces the impact of the retainer when preventing the accumulated fluid from slipping off and falling back, a method for using the plunger that reduces the impact of the retainer when preventing the accumulated fluid from slipping off and falling back is proposed, comprising the following steps:

[0051] Preparation: According to the height of the liquid column in the well and the bottom hole pressure, nitrogen gas of a certain pressure is filled into the air filling chamber e from the air filling hole f, so that the piston 200 closes the air vent b, and at the same time, the lower support plate 400 moves downward to ensure that the upper support plate 300 is in a retracted state, such as Figure 2 As shown, the plunger is then dropped into the well stopper position.

[0052] Lifting: When the well is in the shut-in state, the piston 200 is pushed upward by the combined effect of the accumulated liquid in the well and the bottom hole pressure. The piston 200 drives the lower support piece 400 to move together during the upward movement. When the flange 410 on the lower support piece 400 contacts the upper support piece 300, the upper support piece 300 can be driven to move along the inclined surface on the connecting sleeve 500. When the piston 200 reaches the limit ring 900, the piston 200 stops moving. At this time, the upper support piece 300 and the lower support piece 400 are spliced ​​with each other and work together with the inclined surface on the connecting sleeve 500 to form a seal for the accumulated liquid on the upper part. Figure 1 When it is necessary to drain the liquid, the well is opened, and the plunger moves upward under the action of the bottom hole pressure and carries the accumulated liquid to the wellhead to drain the accumulated liquid, thereby performing gas production. It should be noted that the vent b is located at the lower part of the buffer chamber a. When the plunger reaches the wellhead, the liquid in the buffer chamber a can be discharged through the vent b, and the gas can enter the buffer chamber a at the same time.

[0053] Falling back: After the plunger is at the wellhead, due to the reduction of the pressure of the accumulated liquid column and the pressure in the well, the piston 200 moves down and resets under the thrust of the gas in the inflation chamber e. During the downward movement of the piston 200, the lower support plate 400 is also driven downward. During the downward movement of the lower support plate 400, the linkage retaining ring 700 is driven downward, and then the upper support plate 300 is driven downward through the linkage retaining ring 700, thereby realizing the reset of the piston 200, the lower support plate 400, and the upper support plate 300. At this time, the upper support plate 300 is close to the central pipe 100, and the distance from the inner wall of the production pipe string is increased, which is conducive to reducing the wear of the upper support plate 300 and ensuring the smooth fall of the plunger. When the piston 200 is reset, the vent b is blocked, so that a certain amount of gas is sealed in the central pipe 100, such as Figure 2 As shown, the relative density of the plunger is reduced, the plunger's falling speed is slowed down, and it is helpful to reduce the impact of the plunger's falling on the retainer.

[0054] 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 it. 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 with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A plunger for reducing the impact of a retainer when preventing accumulated fluid from slipping and falling back, characterized in that: It comprises a central tube (100), a piston (200), an upper supporting plate (300) and a lower supporting plate (400); A buffer cavity (a) is provided inside the central tube (100), and a vent hole (b) communicating with the buffer cavity (a) is provided on the side wall; The piston (200) is sleeved on the central tube (100) and is slidably connected to the central tube (100); The lower supporting plate (400) is connected to the piston (200), and the upper supporting plate (300) is connected to the central tube (100); A plurality of the upper supporting plates (300) and the lower supporting plates (400) are evenly distributed in an annular shape around the central tube (100) and are arranged at intervals; After the piston (200) moves upward, the vent hole (b) is opened and the lower supporting plate (400) is driven to push the upper supporting plate (300), so that the upper supporting plate (300) moves in a direction away from the central tube (100); After the piston (200) moves downward, it closes the vent hole (b) and drives the lower supporting plate (400) to move so that the upper supporting plate (300) moves in a direction close to the central tube (100).

2. The plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping off and falling back according to claim 1 is characterized in that: It also includes a connecting sleeve (500), wherein the connecting sleeve (500) is connected to the central tube (100) and is sleeved on the piston (200); The connecting sleeve (500) contacts the upper supporting plate (300) and the contact surface is an inclined surface.

3. The plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping off and falling back according to claim 2 is characterized in that: It also includes a limiting pin (600), wherein the limiting pin (600) is inserted into the upper supporting plate (300) and connected to the connecting sleeve (500); The upper supporting plate (300) is provided with a long hole (c), and the limiting pin (600) is inserted into the long hole (c) and can slide along the long hole (c).

4. The plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping off and falling back according to claim 3 is characterized in that: It also comprises a linkage snap ring (700), wherein the linkage snap ring (700) is sleeved on the connection sleeve (500), and the upper supporting plate (300) and the lower supporting plate (400) are both connected to the linkage snap ring (700).

5. The plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping off and falling back according to claim 4 is characterized in that: The upper supporting plate (300) and the lower supporting plate (400) are both provided with linkage grooves (d), and the linkage clamping ring (700) is inserted into the linkage grooves (d) and can move relative to the linkage grooves (d) along the axial direction of the central tube (100).

6. The plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping off and falling back according to claim 5, characterized in that: It also includes a one-way valve group (800), wherein the one-way valve group (800) is sleeved on the central tube (100) and connected to the central tube (100), and the one-way valve group (800) is inserted into the connecting sleeve (500) and connected to the connecting sleeve (500); The piston (200) is inserted into the annular space surrounded by the central tube (100) and the connecting sleeve (500), thereby forming an air-filled cavity (e) together with the central tube (100), the connecting sleeve (500) and the one-way valve assembly (800).

7. The plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping off and falling back according to claim 6, characterized in that: The one-way valve assembly (800) comprises a valve seat (810), a valve core (820), a spring (830) and a support seat (840); The valve seat (810) is sleeved on the central tube (100) and connected to the central tube (100), and the valve seat (810) is inserted into the connecting sleeve (500) and connected to the connecting sleeve (500); The valve seat (810) is provided with an air filling hole (f), the valve core (820) and the spring (830) are arranged in the air filling hole (f), and the support seat (840) is inserted into the valve seat (810); One end of the spring (830) is connected to the support seat (840), and the other end is connected to the valve core (820), and is configured to apply a thrust to the valve core (820) so that the valve core (820) blocks the inflation hole (f).

8. The plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping off and falling back according to claim 7, characterized in that: It also includes a limiting ring (900), which is sleeved on the central tube (100) and arranged between the one-way valve group (800) and the piston (200).

9. The plunger for reducing the impact of the retainer when preventing the accumulated fluid from slipping off and falling back according to claim 8, characterized in that: It also comprises a pressure cap (1000), wherein the pressure cap (1000) is inserted into the central tube (100) and connected to the central tube (100) to seal the buffer chamber (a).

10. A method for using a plunger for reducing the impact of a retainer when preventing fluid accumulation from slipping off and falling back, using the plunger for reducing the impact of a retainer when preventing fluid accumulation from slipping off and falling back as claimed in any one of claims 1 to 9, characterized in that: The steps include: Lifting: During the lifting process, the piston (200) moves upward to drive the lower supporting plate (400), so that the lower supporting plate (400) pushes the upper supporting plate (300) away from the central pipe (100), thereby reducing the gap between the upper supporting plate (300) and the inner wall of the production pipe string; Falling back: During the falling back process, the piston (200) moves downward to close the vent hole (b), and at the same time drives the lower support plate (400) to move downward so that the upper support plate (300) is close to the central tube (100).

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