Multi-stage plunger clamping device

Abstract

The invention relates to the field of oil and gas field exploitation, in particular to a clamping device for a multi-stage plunger, and aims to solve the technical problem that an existing clamping device is not suitable for the multi-stage plunger. According to the clamping device for the multi-stage plunger, extrusion and expansion sealing of the expansion rubber sleeve are achieved through sliding of the connecting cylinder, so that sealing is formed between the clamping device and the inner wall of an oil pipe, a one-way valve is formed through matching of the plugging ball and the ball seat, accumulated liquid is prevented from falling back, and bidirectional impact can be borne through the first buffering assembly and the second buffering assembly; and the purpose of adapting to the multi-stage plunger is achieved.

Description

Technical Field

[0001] The invention relates to the field of oil and gas field exploitation, and in particular to a retainer for a multi-stage plunger. Background Art

[0002] With the development of plunger technology, multi-stage plungers have gradually emerged in the field due to their advantages such as low plunger starting pressure and high drainage efficiency, and have broad application prospects. Multi-stage plungers require that the downhole retainer can withstand its bidirectional impact, and the accumulated liquid can only flow from bottom to top in the retainer and cannot fall back. However, the existing retainer can only withstand the downward impact of the upper plunger, and there is a gap with the inner wall of the oil pipe, which cannot be sealed and cannot meet the above requirements. Summary of the invention

[0003] The object of the present invention is to provide a retainer for a multi-stage plunger to solve the technical problem that the existing retainer cannot be applied to the multi-stage plunger.

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

[0005] The multi-stage plunger retainer provided by the present invention comprises: a sealing assembly, a retaining assembly, a first buffer assembly and a second buffer assembly;

[0006] The sealing assembly includes a connecting tube, a flow nipple and an expansion rubber tube; wherein the connecting tube is sleeved on the flow nipple and slidably cooperates with the flow nipple; one end of the flow nipple is arranged in the connecting tube, and the other end extends to the outside of the connecting tube; the expansion rubber tube is fixedly sleeved on the flow nipple and is outside the connecting tube;

[0007] The locking assembly is fixedly connected to the end of the flow nipple away from the connecting tube, and is configured to be anchored to the coupling seam of the oil pipe under delivery conditions;

[0008] The first buffer assembly and the second buffer assembly are fixedly connected to the sealing assembly and the locking assembly respectively, and both can form a rebound force in the opposite direction of the impact force under an impact condition;

[0009] The first buffer assembly includes a guide seat, which is connected to the connecting tube, and a ball seat is fixedly arranged in the guide seat, and a sealing ball is movably arranged; wherein the ball seat is cylindrical, and its two openings are respectively connected to the guide seat and the connecting tube; the sealing ball is located on the side of the ball seat away from the connecting tube, and can move along the axial direction of the guide seat, and its diameter is larger than the inner diameter of the ball seat.

[0010] Furthermore, the locking assembly includes an elastic claw, a locking member, a sliding sleeve and a supporting short section;

[0011] The elastic claw is fixedly sleeved on the sliding sleeve;

[0012] The locking member is arranged at the claw of the elastic claw and makes the claws close toward each other. The locking member is configured to release the locking of the claws when it moves to the coupling seam under the lifting condition;

[0013] The sliding sleeve is sleeved on the supporting short section and can slide along the axial direction of the supporting short section;

[0014] The supporting nipple has a first end and a second end respectively located inside and outside the sliding sleeve, wherein the first end can move toward the claw when the sliding sleeve slides to open the claw, and the second end is fixedly connected to the flow nipple.

[0015] Furthermore, the elastic claw comprises a fixed section and two elastic plates spaced apart and symmetrically distributed about the axis of the fixed section;

[0016] The fixed section is fixedly sleeved on the sliding sleeve;

[0017] The elastic plate is flush with the side surface of the fixing section, and one end of the elastic plate is fixedly connected to the end surface of the fixing section, and the other end of the elastic plate extends in a direction away from the fixing section;

[0018] The clamping claws are provided with two and are respectively fixedly connected to the free ends of the two elastic plates.

[0019] Further, the locking member includes a torsion spring;

[0020] The torsion spring corresponds to the claws one by one, and one end of the torsion spring is hinged to one of the claws, and the other end extends to bypass the other claw and then extends toward the elastic plate, and the distance from the axis of the fixed section gradually increases.

[0021] Furthermore, protrusions are formed on the opposite wall surfaces of the two elastic plates, and the protrusions are directly opposite to the claws;

[0022] The first end outer fixed sleeve is provided with a support head, and the support head can abut against the protrusion when the sliding sleeve is in a sliding condition.

[0023] Further, the claw has a boss;

[0024] In the axial direction of the fixing section, two opposite side surfaces of the boss are respectively a plane and an inclined surface, wherein the plane is away from the fixing section, and the inclined surface extends from the outer wall of the elastic plate in a direction away from the elastic plate and close to the plane.

[0025] Furthermore, the sliding sleeve is provided with a telescopic groove penetrating through its side wall and extending along its own axial direction, and the telescopic groove is used to pass through the claw and the locking member;

[0026] The second buffer assembly is fixedly connected to the sliding sleeve.

[0027] Furthermore, the sealing assembly also includes a cone;

[0028] The cone is sleeved on the flow nipple and fixedly connected to the connecting tube, and the small end of the cone is directly opposite to the expansion rubber tube.

[0029] Further, the first buffer assembly also includes a first center rod, a fishing head and a first compression spring;

[0030] The guide seat is sleeved on the first center rod and slidably cooperates with the first center rod;

[0031] One end of the first center rod is disposed in the guide seat, and the other end is outside the guide seat and fixedly connected to the fishing head;

[0032] The first compression spring is sleeved on the first center rod, and two ends of the first compression spring are respectively in contact with the fishing head and the guide seat.

[0033] Further, the second buffer assembly includes a support seat, a second center rod, an impact head and a second compression spring;

[0034] The support seat is fixedly connected to the locking assembly, and is sleeved on the second center rod and slidably matched with the second center rod;

[0035] One end of the second center rod is disposed in the support seat, and the other end is located outside the support seat and fixedly connected to the impact head;

[0036] The second compression spring is sleeved on the second center rod, and two ends of the second compression spring are respectively in contact with the impact head and the support seat.

[0037] In summary of the above technical solutions, the technical effects that can be achieved by the multi-stage plunger retainer provided by the present invention are:

[0038] In the retainer for the multi-stage plunger, when the expansion rubber cylinder moves toward the connecting tube along with the flow-through short joint, it will be squeezed by the connecting tube, and as the movement continues, the expansion rubber cylinder will expand and seal; after receiving the force toward the ball seat, the blocking ball will sit on the ball seat and block one of the openings of the ball seat, so that the connection between the guide seat and the connecting tube is blocked, and after receiving the force away from the ball seat, the blocking ball will move axially along the guide seat to leave the ball seat, so that the guide seat and the connecting tube are connected.

[0039] When in use, the multi-stage plunger is delivered into the oil pipe through the delivery pipe string with a retainer, and is anchored by cooperating with the retaining assembly and the coupling seam; after anchoring is completed, as the weight of the delivery pipe string continues to be loaded, the connecting tube will slide downward until the expansion rubber tube is squeezed to a seal, so that a seal is formed between the retainer and the inner wall of the oil pipe; through the cooperation of the sealing ball and the ball seat, when the accumulated liquid flows from bottom to top, it will break open the sealing ball, enter the guide seat, and then flow out from the guide seat; when it flows from top to bottom, the sealing ball will be sealed on the ball seat under the corresponding impact force and gravity, so that the accumulated liquid cannot fall back; through the first buffer assembly and the second buffer assembly, the retainer can withstand the downward impact of the upper plunger on it, and can also withstand the upward impact of the lower plunger on it, meeting the requirement of being able to withstand bidirectional impact.

[0040] It can be seen that compared with the prior art, after the multi-stage plunger is anchored and sealed under delivery conditions, it can withstand the bidirectional impact of the upper and lower plungers, and the accumulated liquid on the top will not fall back. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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.

[0042] Figure 1 A partial cross-sectional view of the first section of a multi-stage plunger retainer provided in an embodiment of the present invention;

[0043] Figure 2 A partial cross-sectional view of the second section of the multi-stage plunger retainer provided in an embodiment of the present invention;

[0044] Figure 3 A cross-sectional view of an elastic claw provided by an embodiment of the present invention;

[0045] Figure 4 A schematic diagram of the structure of a locking member provided in an embodiment of the present invention;

[0046] Figure 5 A cross-sectional view of a sliding sleeve provided in an embodiment of the present invention;

[0047] Figure 6 for Figure 5 Cross-sectional view along AA direction;

[0048] Figure 7 for Figure 5 Cross-sectional view along direction BB;

[0049] Figure 8A half-section view of a flow guide seat provided in an embodiment of the present invention;

[0050] Fig. 9 A front view of a first center rod provided in an embodiment of the present invention;

[0051] Fig.10 A partial cross-sectional view of the first section of the multi-stage plunger retainer provided by an embodiment of the present invention when in use;

[0052] Fig.11 A partial cross-sectional view of the second section of the multi-stage plunger retainer provided in an embodiment of the present invention when in use.

[0053] Icons: 1-connecting tube; 2-current passing nipple; 3-expansion rubber tube;

[0054] 4-Oil pipe; 4.1-Coupling seam;

[0055] 5- diversion seat; 6- ball seat; 7- blocking ball;

[0056] 8-elastic claw; 8.1-claw; 8.2-fixed section; 8.3-elastic plate; 8.1.1-boss; 8.3.1-protrusion;

[0057] 9-locking piece;

[0058] 10-sliding sleeve; 10.1-telescopic slot;

[0059] 11-support short section; 12-support head; 13-cone; 14-first center rod; 15-fishing head; 16-first compression spring; 17-support seat; 18-second center rod; 19-impact head; 20-second compression spring; 21-metal pad; 22-conversion short section; 23-first connecting sleeve; 24-second connecting sleeve. DETAILED DESCRIPTION

[0060] 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.

[0061] 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.

[0062] 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.

[0063] The multi-stage plunger requires that the downhole retainer can withstand its bidirectional impact, and the accumulated fluid can only flow from bottom to top in the retainer and cannot fall back. However, the existing retainer can only withstand the downward impact of the upper plunger, and there is a gap with the inner wall of the oil pipe, which cannot be sealed and cannot meet the above requirements.

[0064] In view of this, the present invention provides a multi-stage plunger retainer, comprising a sealing assembly, a retaining assembly, a first buffer assembly and a second buffer assembly; the sealing assembly comprises a connecting tube 1, a flow short section 2 and an expansion rubber tube 3; wherein the connecting tube 1 is sleeved on the flow short section 2 and slidably cooperates with the flow short section 2; one end of the flow short section 2 is arranged in the connecting tube 1, and the other end extends to the outside of the connecting tube 1; the expansion rubber tube 3 and the metal pad 21 are vulcanized into one body to form a composite rubber tube, and the metal pad 21 is threadedly connected to the flow short section 2; the retaining assembly is fixedly connected to the end of the flow short section 2 away from the connecting tube 1, and is configured to be in the delivery condition. Down, anchored in the coupling seam 4.1 of the oil pipe 4; the first buffer assembly and the second buffer assembly are fixedly connected to the sealing assembly and the locking assembly respectively, and both can form a rebound force in the opposite direction of the impact force under impact conditions; the first buffer assembly includes a guide seat 5, the guide seat 5 is connected to the connecting tube 1, and a ball seat 6 is fixedly arranged in the guide seat 5, and a blocking ball 7 is movably arranged; wherein, the ball seat 6 is cylindrical, and its two openings are connected to the guide seat 5 and the connecting tube 1 respectively; the blocking ball 7 is located on the side of the ball seat 6 away from the connecting tube 1, and can move along the axial direction of the guide seat 5, and its diameter is larger than the inner diameter of the ball seat 6.

[0065] In the multi-stage plunger retainer, when the expansion rubber cylinder 3 moves toward the connecting tube 1 along with the flow short section 2, it will be squeezed by the connecting tube 1, and as the movement continues, the expansion rubber cylinder 3 will be expanded and sealed; after receiving the force toward the ball seat 6, the blocking ball 7 will sit on the ball seat 6 and block one of the openings of the ball seat 6, so that the connection between the guide seat 5 and the connecting tube 1 is blocked, and after receiving the force away from the ball seat 6, the blocking ball 7 will move axially along the guide seat 5 to leave the ball seat 6, so that the guide seat 5 and the connecting tube 1 are connected.

[0066] When in use, the multi-stage plunger is delivered into the oil pipe 4 through the delivery pipe string with a retainer, and is anchored by cooperating with the retaining assembly and the coupling seam 4.1; after the anchoring is completed, as the weight of the delivery pipe string continues to be loaded, the connecting tube 1 will slide downward until the expansion rubber tube 3 is squeezed and sealed, so that the retainer forms a seal with the inner wall of the oil pipe 4; through the cooperation of the blocking ball 7 and the ball seat 6, when the accumulated liquid flows from bottom to top, it will break through the blocking ball 7, enter the guide seat 5, and then flow out from the guide seat 5. When flowing from top to bottom, the blocking ball 7 will be blocked on the ball seat 6 under the corresponding impact force and gravity, so that the accumulated liquid cannot fall back; through the first buffer assembly and the second buffer assembly, the retainer can withstand the downward impact of the upper plunger on it, and can also withstand the upward impact of the lower plunger on it, meeting the requirement of being able to withstand bidirectional impact.

[0067] It can be seen that compared with the prior art, after the multi-stage plunger is anchored and sealed under delivery conditions, it can withstand the bidirectional impact of the upper and lower plungers, and the accumulated liquid on the top will not fall back.

[0068] The following combination Figures 1 to 11 The structure and shape of the multi-stage plunger retainer provided in this embodiment are described in detail:

[0069] For further reference, Figure 1 and Figure 2 The locking assembly includes an elastic claw 8, a locking member 9, a sliding sleeve 10 and a supporting short section 11; the elastic claw 8 is fixedly sleeved on the sliding sleeve 10; the locking member 9 is arranged at the claw 8.1 of the elastic claw 8, and makes each claw 8.1 close toward each other, and the locking member 9 is configured to release the locking of each claw 8.1 when it moves to the coupling seam 4.1 under the lifting condition; the sliding sleeve 10 is threadedly connected with the first connecting sleeve 23, and the two cooperate to form an axial limit for the elastic claw 8, To prevent the elastic claw 8 from moving on the sliding sleeve 10, the sliding sleeve 10 is sleeved on the supporting short section 11 and can slide along the axial direction of the supporting short section 11; the supporting short section 11 has a first end and a second end respectively located inside and outside the sliding sleeve 10, wherein the first end can move toward the claw 8.1 under the sliding condition of the sliding sleeve 10 to open the claw 8.1, and the second end is threadedly connected to the conversion short section 22, and the conversion short section 22 is threadedly connected to the flow short section 2.

[0070] Specifically, when the anchor is lowered, it is delivered into the oil pipe 4 through the delivery pipe string. When the delivery pipe string is lowered to 5 to 8 meters below the position of the coupling seam 4.1, the lowering is stopped; then the delivery pipe string is slowly lifted up, and when the locking member 9 passes through the coupling seam 4.1, the locking of each claw 8.1 is released, and the claw 8.1 is restored to the initial state and anchored in the coupling seam 4.1; then the delivery pipe string is continuously lifted up, so that the suspended weight of the well testing vehicle will have an obvious fluctuation process, and then the delivery pipe string is slowly lowered again. Since the claw 8.1 is anchored in cooperation with the coupling seam 4.1, the delivery pipe string cannot continue to descend, and its weight will be fully transferred to the supporting short section 11; the supporting short section 11 is subjected to the pressure from the delivery pipe string, that is, it descends, and its first end moves toward the claw 8.1 of the elastic claw 8, so that the claw 8.1 cannot shrink, thereby maintaining the anchoring with the coupling seam 4.1.

[0071] Preferably, reference Figure 3 The elastic claw 8 includes a fixed section 8.2 and two elastic plates 8.3 that are spaced apart and symmetrically distributed about the axis of the fixed section 8.2; the fixed section 8.2 is fixedly sleeved on the sliding sleeve 10; the elastic plate 8.3 is flush with the side surface of the fixed section 8.2, and one end of the elastic plate 8.3 is fixedly connected to the end surface of the fixed section 8.2, and the other end extends away from the fixed section 8.2; there are two claws 8.1, which are fixedly connected to the free ends of the two elastic plates 8.3 respectively. Figure 2 and Figure 4 As shown, the locking member 9 includes a torsion spring; the torsion spring corresponds to the claws 8.1 one by one, and one end of the torsion spring is hinged to one of the claws 8.1, and the other end extends to bypass the other claw 8.1, and then extends toward the direction close to the elastic plate 8.3, and the distance from the axis of the fixed section 8.2 gradually increases. Figures 5 to 7 The sliding sleeve 10 is provided with a telescopic groove 10.1 penetrating through its side wall and extending along its own axial direction, and the telescopic groove 10.1 is used to pass the claw 8.1 and the torsion foot of the torsion spring; the second buffer assembly is fixedly connected to the sliding sleeve 10.

[0072] In the above design, under the limit of the torsion spring, the two claws 8.1 are locked together, and the two elastic plates 8.3 are adaptively deformed, so that during the lowering process, the retainer will not be locked with the coupling seam 4.1, thereby ensuring that the retainer is smoothly lowered into the well, and the lowering process is stable and not limited by the lowering speed; when lifting the delivery pipe string, refer to Fig.10 and Fig.11 When the torsion foot of the torsion spring enters the coupling seam 4.1, the torsion spring will rotate around the hinge axis between it and the corresponding claw 8.1 to release the clamping of the other claw 8.1. In this way, under the action of the restoring force of the elastic plate 8.3, the two claws 8.1 will open, extend out of the telescopic slot 10.1, and then enter the coupling seam 4.1 to achieve anchoring.

[0073] For further reference, Figure 1The sealing assembly also includes a cone 13; the cone 13 is sleeved on the flow nipple 2 and fixedly connected to the connecting tube 1, and the small end of the cone 13 is directly opposite to the expansion rubber tube 3. Figure 2 The claw 8.1 has a boss 8.1.1; in the axial direction of the fixed section 8.2, the two opposite sides of the boss 8.1.1 are a plane and an inclined surface, wherein the plane is away from the fixed section 8.2, and the inclined surface extends from the outer wall of the elastic plate 8.3 to a direction away from the elastic plate 8.3 and close to the plane. Figure 2 and Figure 3 , protrusions 8.3.1 are formed on the opposite wall surfaces of the two elastic plates 8.3, and the protrusions 8.3.1 are directly opposite to the claws 8.1; a support head 12 is provided on the fixed sleeve outside the first end, and the support head 12 can abut against the protrusion 8.3.1 when the sliding sleeve 10 slides.

[0074] Specific, combined Fig.11 As shown, after the claw 8.1 is anchored with the coupling seam 4.1, the protrusion 8.3.1 can be regarded as a right-angle step structure, which forms a stable limit with the coupling seam 4.1 and cannot continue to move downward. At this time, the weight of the delivery pipe string is completely transferred to the support short section 11, and the support short section 11 immediately moves downward; the support head 12 moves toward the claw 8.1 under the drive of the support short section 11 until it abuts against the protrusion 8.3.1 to form a limit, at which time the support short section 11 cannot continue to move downward, and the elastic claw 8 is anchored with the coupling seam 4.1; as the weight of the delivery pipe string continues to be loaded, the cone 13 moves downward with the connecting tube 1, and its lower end penetrates into the expansion rubber cylinder 3, so that the expansion rubber cylinder 3 is expanded and sealed to form a seal with the inner wall of the oil pipe 4.

[0075] Further, combined with Figure 1 , Figure 8 and Fig. 9 As shown, the first buffer assembly also includes a first center rod 14, a salvage head 15 and a first compression spring 16; the guide seat 5 is sleeved on the first center rod 14 and slidably cooperates with the first center rod 14; one end of the first center rod 14 is arranged in the guide seat 5, and the other end is outside the guide seat 5 and fixedly connected to the salvage head 15; the first compression spring 16 is sleeved on the first center rod 14, and its two ends are respectively abutted against the salvage head 15 and the guide seat 5.

[0076] Specifically, Figure 1 For example, with the above design, when the fishing head 15 is impacted downward, it drives the first center rod 14 to slide downward, and compresses the first compression spring 16 at the same time. After the impact force disappears, the first center rod 14 slides upward and returns to its initial position under the action of the restoring force of the first compression spring 16. With this design, the retainer can withstand the downward impact of the upper plunger.

[0077] For further reference, Figure 2The second buffer assembly includes a second connecting sleeve 24, a support seat 17, a second center rod 18, an impact head 19 and a second compression spring 20; the upper end of the second connecting sleeve 24 is threadedly connected to the sliding sleeve 10, and the lower end is threadedly connected to the support seat 17; the support seat 17 is sleeved on the second center rod 18 and slidably cooperates with the second center rod 18; one end of the second center rod 18 is arranged in the support seat 17, and the other end is outside the support seat 17 and fixedly connected to the impact head 19; the second compression spring 20 is sleeved on the second center rod 18, and its two ends are respectively abutted against the impact head 19 and the support seat 17.

[0078] Continue to refer Figure 2 When the impact head 19 is impacted upward, it drives the second center rod 18 to slide upward and compresses the second compression spring 20. After the impact force disappears, the second center rod 18 slides downward and returns to its initial position under the action of the restoring force of the second compression spring 20. This design allows the retainer to withstand the upward impact of the lower plunger.

[0079] The anchoring and sealing process of the multi-stage plunger retainer provided in this embodiment is as follows:

[0080] The delivery pipe string includes from top to bottom: steel wire, rope cap, weight rod, jar, delivery bucket, and multi-stage plunger retainer, among which steel wire, rope cap, weight rod, jar, and delivery bucket are all supporting tools for conventional steel wire operations.

[0081] refer to Figure 1 and Figure 2 When the multi-stage plunger is lowered, the two torsion springs lock the two claws 8.1 together. When the delivery pipe string is lowered to 5 to 8 meters below the coupling seam 4.1, the lowering is stopped; then the delivery pipe string is slowly lifted up. When the retainer passes the designed coupling seam 4.1 position, the torsion spring will act on the coupling seam 4.1 and pop open, and the elastic claw 8 will return to a free state. Fig.11 As shown, at this time, the claw 8.1 will be anchored in the coupling seam 4.1; then continue to lift the delivery pipe string, the suspended weight of the well testing vehicle will have an obvious fluctuation process, and at this time slowly lower the delivery pipe string. Since the claw 8.1 and the coupling seam 4.1 will form a stable limit after anchoring, it cannot continue to descend. At this time, the weight of the delivery pipe string will be fully transferred to the support short section 11; the support short section 11 will then descend until the support head 12 and the protrusion 8.3.1 form a limit, at this time the support short section 11 cannot continue to descend, and the elastic claw 8 and the coupling seam 4.1 are anchored; as the weight of the delivery pipe string continues to be loaded, the cone 13 descends along the flow short section 2 until it cooperates with the expansion rubber cylinder 3 and expands and seals the expansion rubber cylinder 3, at this time the expansion rubber cylinder 3 and the inner wall of the oil pipe 4 form a seal. After anchoring and sealing are completed, the shear nails of the delivery bucket are cut by hammering down the jar, and the delivery bucket is separated from the fishing head 15, and the delivery pipe is pulled up and strung out of the wellhead, and the fixing device is deployed.

[0082] The salvaging and unsealing process of the multi-stage plunger retainer provided in this embodiment is as follows:

[0083] The salvage pipe string includes: steel wire, rope cap, weight rod, jar and salvage bucket.

[0084] refer to Fig.10 and Fig.11 , lower the salvage pipe string into the wellbore. When the salvage pipe string is lowered to the upper part of the multi-stage plunger retainer, the salvage bucket will be connected to the salvage head 15, and then the salvage pipe string will be lifted up. Under the action of the lifting force, the cone 13 will first be separated from the expansion rubber cylinder 3, and the expansion rubber cylinder 3 will be unsealed immediately; as the cone 13 continues to move upward until it contacts the flow-through short section 2, the flow-through short section 2 drives the support short section 11 to move upward. When the support head 12 driven by the support short section 11 contacts the sliding sleeve 10, the sliding sleeve 10 drives the elastic claw 8 to move upward. Since the top of the boss 8.1.1 is an inclined surface, and the elastic claw 8 is not supported by the support head 12 at this time, the clamping claw 8.1 can easily withdraw from the coupling seam 4.1 to achieve unsealing; continue to lift the salvage pipe string, and the retainer will be salvaged out of the wellbore.

[0085] 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 multi-stage plunger retainer, characterized in that: include: A sealing assembly, a locking assembly, a first buffer assembly, and a second buffer assembly; The sealing assembly comprises a connecting tube (1), a flow nipple (2) and an expansion rubber tube (3); wherein the connecting tube (1) is sleeved on the flow nipple (2) and slidably matched with the flow nipple (2); one end of the flow nipple (2) is arranged in the connecting tube (1) and the other end extends outside the connecting tube (1); the expansion rubber tube (3) is fixedly sleeved on the flow nipple (2) and is outside the connecting tube (1); The locking assembly is fixedly connected to the end of the flow nipple (2) away from the connecting tube (1), and is configured to be anchored to the coupling seam (4.1) of the oil pipe (4) under delivery conditions; The first buffer assembly and the second buffer assembly are fixedly connected to the sealing assembly and the locking assembly respectively, and both can form a rebound force in the opposite direction of the impact force under an impact condition; The first buffer assembly comprises a guide seat (5), the guide seat (5) is connected to the connecting tube (1), and a ball seat (6) is fixedly arranged inside the guide seat (5), and a blocking ball (7) is also movably arranged; wherein the ball seat (6) is cylindrical, and its two openings are respectively connected to the guide seat (5) and the connecting tube (1); the blocking ball (7) is located on the side of the ball seat (6) away from the connecting tube (1), and can move along the axial direction of the guide seat (5), and its diameter is larger than the inner diameter of the ball seat (6).

2. The multi-stage plunger retainer according to claim 1, characterized in that: The locking assembly comprises an elastic claw (8), a locking member (9), a sliding sleeve (10) and a supporting short section (11); The elastic claw (8) is fixedly sleeved on the sliding sleeve (10); The locking member (9) is arranged at the claw (8.1) of the elastic claw (8) and makes the claws (8.1) close toward each other. The locking member (9) is configured to release the locking of the claws (8.1) when it moves to the coupling seam (4.1) under the lifting condition; The sliding sleeve (10) is sleeved on the supporting short section (11) and can slide along the axial direction of the supporting short section (11); The supporting nipple (11) comprises a first end and a second end respectively located inside and outside the sliding sleeve (10), wherein the first end is capable of moving toward the claw (8.1) when the sliding sleeve (10) is in a sliding condition so as to open the claw (8.1), and the second end is fixedly connected to the flow-through nipple (2).

3. The multi-stage plunger retainer according to claim 2, characterized in that: The elastic claw (8) comprises a fixed section (8.2) and two elastic plates (8.3) spaced apart and symmetrically distributed about the axis of the fixed section (8.2); The fixed section (8.2) is fixedly sleeved on the sliding sleeve (10); The elastic plate (8.3) is flush with the side surface of the fixed section (8.2), one end of which is fixedly connected to the end surface of the fixed section (8.2), and the other end of which extends in a direction away from the fixed section (8.2); Two clamping claws (8.1) are provided and are respectively fixedly connected to the free ends of the two elastic plates (8.3).

4. The multi-stage plunger retainer according to claim 3, characterized in that: The locking member (9) comprises a torsion spring; The torsion spring corresponds to the claws (8.1) one by one, and one end of the torsion spring is hinged to one of the claws (8.1), and the other end extends to bypass the other claw (8.1) and then extends in a direction close to the elastic plate (8.3), and the distance between the torsion spring and the axis of the fixed section (8.2) gradually increases.

5. The multi-stage plunger retainer according to claim 3, characterized in that: The opposite wall surfaces of the two elastic plates (8.3) are both protruded to form a protrusion (8.3.1), and the protrusion (8.3.1) is directly opposite to the claw (8.1); The first end outer fixed sleeve is provided with a support head (12), and the support head (12) can abut against the protrusion (8.3.1) when the sliding sleeve (10) is in a sliding condition.

6. The multi-stage plunger retainer according to claim 3, characterized in that: The claw (8.1) has a boss (8.1.1); In the axial direction of the fixing section (8.2), two opposite side surfaces of the boss (8.1.1) are respectively a plane and an inclined surface, wherein the plane is away from the fixing section (8.2), and the inclined surface extends from the outer wall of the elastic plate (8.3) in a direction away from the elastic plate (8.3) and close to the plane.

7. The multi-stage plunger retainer according to claim 2, characterized in that: The sliding sleeve (10) is provided with a telescopic groove (10.1) penetrating through its side wall and extending along its own axial direction, and the telescopic groove (10.1) is used to pass through the claw (8.1) and the locking member (9); The second buffer assembly is fixedly connected to the sliding sleeve (10).

8. The multi-stage plunger retainer according to claim 1, characterized in that: The sealing assembly also includes a cone (13); The cone (13) is sleeved on the flow nipple (2) and fixedly connected to the connecting tube (1), and the small end of the cone (13) is directly opposite to the expansion rubber tube (3).

9. The multi-stage plunger retainer according to claim 1, characterized in that: The first buffer assembly also includes a first central rod (14), a fishing head (15) and a first compression spring (16); The guide seat (5) is sleeved on the first center rod (14) and slidably matched with the first center rod (14); One end of the first center rod (14) is arranged in the guide seat (5), and the other end is located outside the guide seat (5) and fixedly connected to the fishing head (15); The first compression spring (16) is sleeved on the first center rod (14), and its two ends are respectively in contact with the fishing head (15) and the guide seat (5).

10. The multi-stage plunger retainer according to claim 1, characterized in that: The second buffer assembly comprises a support seat (17), a second center rod (18), an impact head (19) and a second compression spring (20); The support seat (17) is fixedly connected to the locking assembly, and is sleeved on the second center rod (18), and is slidably matched with the second center rod (18); One end of the second center rod (18) is arranged in the support seat (17), and the other end is located outside the support seat (17) and is fixedly connected to the impact head (19); The second compression spring (20) is sleeved on the second center rod (18), and its two ends are respectively in contact with the impact head (19) and the support seat (17).

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