Cement retainer

Abstract

The invention discloses a cement retaining device, which relates to the technical field of petroleum drilling, and comprises an upper joint, a long central pipe and a sealing sleeve, a piston is fixed through a setting shear pin and is hydraulically driven to act; the lower end of the piston is connected with an elastic claw and can transmit setting force and achieve releasing separation, and the lower portion of the piston is connected with a compression cylinder and an upper conical head in series through a claw connector. The anchoring mechanism is composed of an upper conical head, a lower conical head, an anchor tooth block and the like and can expand in the radial direction to clamp the casing pipe during setting. The compression sleeve linked with the rubber sleeve assembly can extrude the rubber sleeve assembly to realize sealing; the cement injection channel is composed of a lower connector, a one-way valve and a cement injection head and ensures one-way cement injection. The design that an unblocking fishing head, a thrust ring and inner teeth of a compression cylinder are meshed is adopted in the unblocking mechanism, the thrust ring can be retracted by lifting the fishing head upwards, and therefore anchoring and sealing are relieved. Setting, squeezing and sealing, cement injection and fishing operation are achieved through one pipe column, a large-drift-diameter cement injection channel is provided after releasing, finally, the whole body is fished out of a well, no fish is left at the bottom of the well, drilling and grinding are not needed, and construction operation and well plugging cost is saved.

Description

Technical Field

[0001] This invention relates to the field of oil drilling technology, and in particular to a cement retainer. Background Technology

[0002] Cement retainers are suitable for sealing operations in abandoned wells. They are installed inside the casing to seal the upper and lower sections of the casing, selectively sealing them. Cement retainers are used for staged pressurized cement injection operations inside the casing. They can effectively separate two layers of cement injection operations. While the lower layer of the cement retainer is waiting to set or under pressure, the upper layer can be injected simultaneously. Existing cement retainers are mainly cast iron cement retainers. Except for the rubber bucket part, the cement retainer is made of cast iron or steel with a strength higher than cast iron. The grinding time is long. Under a drilling pressure of 1 ton, the grinding time is about 70 hours, which seriously affects the construction progress and slows down the project progress.

[0003] Current cement retainers use an insert head to bring in the bridge plug, and the seat and extrusion are integrated, but they cannot be retrieved. Because the main body is made of relatively hard cast iron, drilling is difficult and takes a long time. Summary of the Invention

[0004] The purpose of this invention is to provide a cement retainer to solve the problems existing in the prior art, enabling the setting, squeezing, grouting and retrieval operations to be completed in one trip of the tubing string, thereby reducing construction costs and well sealing operation time.

[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides a cement retainer, including an upper connector (1), the inner hole of which is threadedly connected to a long central tube (6), and the outer circumference of the upper connector (1) is connected to a sealing sleeve (3) via threads and a sealing ring. A piston (4) is provided between the sealing sleeve (3) and the long central tube (6), and the piston (4) is in clearance fit with the sealing sleeve (3) and the long central tube (6) via a sealing ring. The piston (4) and the upper connector (1) are connected by a setting shear pin (5). The upper connector (1) has a liquid inlet hole (11) machined on the upper part of the piston (4), and the lower part of the piston (4) is threadedly connected to an elastic claw (7). The lower part of the elastic claw (7) is connected to a claw connector (8). The elastic claw (7) can be separated from the claw joint (8). The lower part of the claw joint (8) is threadedly connected to the compression cylinder (9). The lower part of the compression cylinder (9) is threadedly connected to the upper cone (14). The outer circle of the long central tube (6) is fitted with a short central tube (36) at the upper cone (14). The upper cone (14) and the short central tube (36) are clearance-fitted. The short central tube (36) is fitted with a lower cone (17) at the lower part of the upper cone (14). The lower cone (17) is threadedly connected to the compression sleeve (19). Anchor teeth (15), anchor sleeves (16), and lower locking caps (18) are installed on the outer sides of the opposite ends of the lower cone (17) and the upper cone (14). The short central tube (36) is connected to a rubber sleeve core tube (25) by a threaded connection at the middle outer diameter. The lower part of the rubber sleeve core tube (25) is connected to a lower connector (26) by a threaded connection. A radially expandable rubber sleeve assembly is fitted on the rubber sleeve core tube (25) between the upper end of the lower connector (26) and the lower end of the compression sleeve (19). The lower end of the lower connector (26) is connected to a mortar injection head (30) by a threaded connection. A one-way valve assembly that can only discharge downwards is installed inside the mortar injection head (30). The lower part of the long central tube (6) is connected to a sealing short section (33) by a drop screw (35). The sealing short section (33) and the short central tube (36) are fitted with a sealing ring through a clearance. The sealing short section (33) is connected by a first pin (34). The short central tube (36) is fixedly connected, and the lower inner hole of the sealing short section (33) is connected to the ball-throwing seat (31) through the channel shear pin (32) and the sealing ring; the upper part of the short central tube (36) is fixedly connected to the unsealing head (10) through the second pin (38), and the short central tube (36) is connected to the thrust seat (13) at the lower part of the unsealing head (10) through the unsealing shear pin (37). The thrust seat (13) has a limiting ring groove machined on the outside, and a thrust ring (12) is installed in the limiting ring groove. The thrust ring (12) has a one-way toothed ring (1201) machined on the outer circle. The upper part of the inner hole of the compression cylinder (9) has a one-way toothed hole (901) that can mesh with the one-way toothed ring (1201).

[0006] Preferably, the thrust ring (12) is made of elastic material. A notch (1202) is opened on one side of the tube wall of the thrust ring (12). The unsealing shear pin (37) supports the thrust ring (12) to expand, so that the one-way toothed ring (1201) is in an elastic meshing position with the one-way toothed hole (901) of the compression cylinder (9). The short central tube (36) has an unsealing ring groove (3601) processed on the lower part of the thrust ring (12). The unsealing head (10) is provided with an outer step sleeve (1003) at the lower part. The claw joint (8) is provided with an inner step sleeve (802) at the upper part. The inner step sleeve (802) is clearance-fitted with the unsealing head (10). The outer step sleeve (1003) is clearance-fitted with the inner hole of the claw joint (8). During installation, a distance is left between the inner step sleeve (802) and the outer step sleeve (1003).

[0007] Preferably, the elastic claw (7) has an inner protruding ring (701) at its lower end, and the claw connector (8) has an outer protruding ring (801) at its upper part. The inner protruding ring (701) is engaged with the lower part of the outer protruding ring (801). The elastic claw (7) has circumferentially distributed slits (702) that cut upwards from the lower part.

[0008] Preferably, the upper part of the unsealing head (10) is machined with an external retrieval thread (1001) and an internal retrieval thread (1002).

[0009] Preferably, a limiting shaft (39) is welded laterally to the lower part of the rubber sleeve core tube (25), and the outer diameter of the lower connector (26) is connected to a protective sleeve (27) by a thread. The protective sleeve (27) is made of nylon material.

[0010] Preferably, the upper connector (1) is threaded with a locking cap (2) on the upper part of the sealing sleeve (3).

[0011] Preferably, the upper part of the ash injection head (30) is connected to the valve ball (28) by a compression spring, and the lower connector (26) is connected to the valve seat (29) on the upper part of the valve ball (28) by a sealing ring and threads. The ash injection head (30) has a through-flow groove (3001) that runs vertically through it. The valve seat (29), the valve ball (28) and the compression spring together form the one-way valve assembly that can only discharge downwards.

[0012] Preferably, the rubber sleeve core tube (25) is fitted with a lower rubber sleeve (24), a spacer ring B (23), a middle rubber sleeve (22), a spacer ring A (21), and an upper rubber sleeve (20) in sequence from bottom to top above the lower connector (26), and the upper rubber sleeve (20) is positioned at the lower end of the compression sleeve (19); the lower rubber sleeve (24), the spacer ring B (23), the middle rubber sleeve (22), the spacer ring A (21), and the upper rubber sleeve (20) together constitute the rubber sleeve assembly.

[0013] The present invention achieves the following technical effects compared to the prior art: The cement retainer provided by this invention enables setting, squeezing, cement injection, and retrieval operations through a single tubing string, saving on construction and well sealing costs. It ensures that positive circulation well washing can be achieved before setting the integrated squeezing tubing string, and provides a large-diameter cement injection channel after release. After manual well bottoming is completed, the cement injection portion can be retrieved and lifted, cement can be injected again to seal the well, and finally the whole thing can be retrieved from the well. It can be reused, leaves no fish at the bottom of the well, requires no drilling, and reduces construction costs and well sealing operation time. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A schematic diagram of the upper structure of the cement retainer provided by the present invention; Figure 2 This is a schematic diagram of the middle structure of the cement retainer provided by the present invention; Figure 3 A schematic diagram of the lower structure of the cement retainer provided by the present invention; Figure 4 for Figure 1 A magnified view of a section at point A in the middle; Figure 5 for Figure 2 Cross-sectional view at point BB; Figure 6 This is a schematic diagram of the structure of the cement retainer during setting according to the present invention; Figure 7 This is a schematic diagram of the structure of the cement retainer provided by the present invention after the long central tube has been pulled out. Figure 8 This is a schematic diagram of the unsealing and retrieval mechanism in the cement retainer provided by the present invention; Figure 9 This is a schematic diagram of the cement retainer provided by the present invention during cement injection; Figure 10 A schematic diagram of the artificial well bottom at the end of cement injection for the cement retainer provided by the present invention.

[0016] In the picture: 1-Upper connector; 2-Upper locking cap; 3-Sealing sleeve; 4-Piston; 5-Setting shear pin; 6-Long center tube; 7-Elastic claw; 701-Inner raised ring; 702-Slit; 8-Claw connector; 801-Outer raised ring; 802-Inner stepped sleeve; 9-Compression cylinder; 901-One-way toothed hole; 10-Unsealing retrieval head; 1001-Outer retrieval thread; 1002-Inner retrieval thread; 1003-Outer stepped sleeve; 11-Liquid inlet hole; 12-Thrust ring; 1201-One-way toothed ring; 1202-Notch; 13-Thrust seat; 14-Upper cone; 15-Anchor block; 16-Anchor block sleeve; 17-Lower cone; 18- 19-Compression sleeve; 20-Upper rubber sleeve; 21-Spacer ring A; 22-Middle rubber sleeve; 23-Spacer ring B; 24-Lower rubber sleeve; 25-Rubber sleeve core tube; 26-Lower connector; 27-Protective sleeve; 28-Valve ball; 29-Valve seat; 30-Powder inlet head; 3001-Flow groove; 31-Ball holder; 32-Channel shear pin; 33-Sealing short section; 34-First pin; 35-Release shear pin; 36-Short center tube; 3601-Unsealing ring groove; 37-Unsealing shear pin; 38-Second pin; 39-Limiting shaft. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The purpose of this invention is to provide a cement retainer to solve the problems existing in the prior art, enabling the setting, squeezing, grouting and retrieval operations to be completed in one trip of the tubing string, thereby reducing construction costs and well sealing operation time.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] Example 1 This embodiment provides a cement retainer, such as Figures 1-10As shown, the device includes an upper connector 1, with a long central tube 6 threaded into its inner bore. A sealing sleeve 3 is connected to the outer circumference of the upper connector 1 via threads and a sealing ring. A piston 4 is positioned between the sealing sleeve 3 and the long central tube 6. The piston 4 is fitted with the sealing sleeve 3 and the long central tube 6 via a clearance fit using a sealing ring. The piston 4 and the upper connector 1 are connected by a setting shear pin 5. An inlet hole 11 is machined on the upper part of the piston 4. An elastic claw 7 is threaded to the lower part of the piston 4. A claw connector 8 is connected to the lower part of the elastic claw 7. A compression cylinder 9 is threaded to the lower part of the claw connector 8. The lower part of the compression cylinder 9 is threadedly connected to the upper cone head 14. The outer circle of the long central tube 6 is fitted with a short central tube 36 at the upper cone head 14. The upper cone head 14 and the short central tube 36 are clearance-fitted. The short central tube 36 is fitted with a lower cone head 17 at the lower part of the upper cone head 14. The lower cone head 17 is threadedly connected to the compression sleeve 19. An anchor block 15, an anchor block sleeve 16 and a lower locking cap 18 are installed between the lower cone head 17 and the upper cone head 14. This structure is a conventional anchoring structure for bridge plugs (this structure is a conventional anchoring structure for bridge plugs, which is existing technology and will not be described in detail). The short center tube 36 is connected to the rubber sleeve core tube 25 by a threaded connection on the outer circle of the middle section. The lower part of the rubber sleeve core tube 25 is connected to the lower connector 26 by a threaded connection. Above the lower connector 26, the rubber sleeve core tube 25 is successively fitted with a lower rubber sleeve 24, a spacer ring B23, a middle rubber sleeve 22, a spacer ring A21, and an upper rubber sleeve 20. The upper rubber sleeve 20 rests on the lower end of the compression sleeve 19. The lower connector 26 is threaded to the ash injection head 30. The upper part of the ash injection head 30 is connected to the valve ball 28 through a compression spring. The lower connector 26 is connected to the valve seat 29 through a sealing ring and threads on the upper part of the valve ball 28. The ash injection head 30 has a through-flow groove 3001. The valve seat 29, the valve ball 28 and the compression spring work together to form a one-way valve assembly that can only discharge downwards. The lower part of the long central tube 6 is connected to the sealing short section 33 by the drop scissor pin 35. The sealing short section 33 and the short central tube 36 are fitted with a sealing ring through a gap. The sealing short section 33 is fixedly connected to the short central tube 36 by the first pin 34. The lower inner hole of the sealing short section 33 is connected to the ball-throwing seat 31 by the channel scissor pin 32 and the sealing ring. The upper part of the short center tube 36 is fixedly connected to the unsealing head 10 by the second pin 38. The lower part of the short center tube 36 is connected to the thrust seat 13 by the unsealing shear pin 37. The thrust seat 13 has a limit ring groove machined on the outside. The thrust ring 12 is installed in the limit ring groove. The outer circle of the thrust ring 12 has a one-way toothed ring 1201 machined. The upper part of the inner hole of the compression cylinder 9 has a one-way toothed hole 901 machined.

[0021] The entire process, including setting, squeezing, cementing, and retrieval, can be accomplished with a single tubing string, saving on construction and well sealing costs. The integrated squeezing tubing string ensures positive circulation well washing before setting and provides a large-diameter cementing channel after being released. After manual well bottoming is completed, the cemented portion can be retrieved and lifted, cemented again for well sealing, and finally the entire string can be retrieved from the well. No fish are left at the bottom of the well, eliminating the need for drilling and reducing construction costs and well sealing time.

[0022] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 2 and Figure 5 As shown, the thrust ring 12 is made of elastic material. A notch 1202 is opened on one side of the pipe wall of the thrust ring 12. The release shear pin 37 supports the expansion of the thrust ring 12, so that the one-way toothed ring 1201 is in an elastic meshing position with the one-way toothed hole 901 of the compression cylinder 9. The short center tube 36 has a release ring groove 3601 machined on the lower part of the thrust ring 12. The release head 10 is provided with an outer stepped sleeve 1003 at the lower part, and the claw joint 8 is provided with an inner stepped sleeve 802 at the upper part. The inner stepped sleeve 802 is clearance-fitted with the release head 10, and the outer stepped sleeve 1003 is clearance-fitted with the inner hole of the claw joint 8. During installation, a distance is left between the inner stepped sleeve 802 and the outer stepped sleeve 1003.

[0023] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 As shown, the lower end of the elastic claw 7 is provided with an inner protruding ring 701, and the upper part of the claw joint 8 is provided with an outer protruding ring 801. The inner protruding ring 701 is stuck in the lower part of the outer protruding ring 801. The elastic claw 7 has circumferentially distributed slits 702. The slits 702 cut upward from the bottom (i.e., the opening of the slits 702 faces downward). When the outer circle of the elastic claw 7 is not constrained, the elastic claw 7 is lifted up, and the slits 702 open, which can separate the two. (When inside the sealing sleeve 3, the lower end of the slits 702 is in a retracted state close to its own axis, that is, the inner protruding ring 701 at the lower end of the elastic claw 7 is in a contracted state. After being removed from the sealing sleeve 3, the inner protruding ring 701 can be in a naturally open state, that is, the slits 702 are open.)

[0024] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 and Figure 4 As shown, the upper part of the unsealing retrieval head 10 is machined with an external retrieval thread 1001 and an internal retrieval thread 1002 for connecting retrieval tools.

[0025] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 3 As shown, a limiting shaft 39 is welded laterally at the lower part of the rubber sleeve core tube 25 to prevent the ball-throwing seat 31 from blocking the ash injection channel of the valve seat 29 when it falls. The lower connector 26 is connected to the protective sleeve 27 by an outer thread. The protective sleeve 27 is made of nylon material and plays a protective role during the well-running process.

[0026] Among the optional solutions in this embodiment, the more preferred one is as follows: Figure 1 As shown, the upper connector 1 is threaded onto the upper part of the sealing sleeve 3 with a locking cap 2 for fixing the sealing sleeve 3.

[0027] Work process (such as) Figures 6-9 (as shown) 1. Apply machine oil to the outside of the lower rubber sleeve 24, lower connector 26 and protective sleeve 27 to detach the solidified cement, lower the cement retainer to the designated well depth, and flush the well with clean water in a positive circulation manner with a volume of not less than 1.5 times the volume of liquid in the tubing string. 2. After the outlet return liquid and pressure are normal, steel balls are put into the oil pipe and pumped to the ball seat 31 for sealing. The tubing is pressurized, the setting shear pin 5 is sheared, and the hydraulic pressure pushes the piston 4 to descend. The descent of the piston 4 pushes the elastic claw 7, claw joint 8, compression cylinder 9 and upper cone head 14 to descend, causing the anchor block 15 to expand outward. At the same time, it pushes the lower cone head 17 to descend, and the rubber sleeve expands until the one-way toothed hole 901 of the sealing cylinder 9 and the one-way toothed ring 1201 of the thrust ring 12 engage, completing the setting seal. 3. Lift the tubing string, release the shear pin 37 to cut it off, and the elastic claw 7 will disengage from the claw connector 8. This will lift the upper connector 1, long central tube 6, sealing sleeve 3, piston 4, and elastic claw 7 out of the tubing string, providing a large-diameter channel for ash injection. 4. A high pulse pressure is generated inside the tubing, the channel shear pin 32 is sheared, the ball-throwing seat 31 falls on the limit shaft 39, the ash injection channel is opened, cement is injected, the cement pushes the valve ball 28 and is injected into the bottom of the well from the flow groove 3001 of the ash injection head 30, completing the artificial well bottom; 5. Lower the retrieval tool and connect the unsealing head 10. The unsealing head 10 moves upward, and the short central tube 36 cuts the unsealing shear pin 37. After the short central tube 36 moves upward, the unsealing ring groove 3601 is located at the position of the unsealing shear pin 37. The unsealing shear pin 37 gains space to move inward, the inner support of the thrust ring 12 is canceled, and the thrust ring 12 retracts under its own elasticity. The one-way toothed ring 1201 disengages from the one-way toothed hole 901. The unsealing head 10 is lifted again, which drives the claw joint 8, the sealing tube 9, and the upper cone head 14 to move upward, thereby unsealing. Move the unsealing head 10 up 100m and inject cement again. Continue this process until the entire well is sealed with cement, thus completing the well sealing operation.

[0028] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A cement retainer, characterized in that: The system includes an upper connector (1), the inner hole of which is threadedly connected to a long central tube (6). The outer circumference of the upper connector (1) is connected to a sealing sleeve (3) via threads and a sealing ring. A piston (4) is provided between the sealing sleeve (3) and the long central tube (6). The piston (4) is in clearance fit with the sealing sleeve (3) and the long central tube (6) via a sealing ring. The piston (4) and the upper connector (1) are connected via a setting shear pin (5). The upper connector (1) has a liquid inlet hole (11) machined on the upper part of the piston (4). The lower part of the piston (4) is threadedly connected to an elastic claw (7). The lower part of the elastic claw (7) is connected to a claw connector (8). The claw (7) can be separated from the claw connector (8). The lower part of the claw connector (8) is threadedly connected to the compression cylinder (9). The lower part of the compression cylinder (9) is threadedly connected to the upper cone (14). The outer circle of the long central tube (6) is fitted with a short central tube (36) at the upper cone (14). The upper cone (14) and the short central tube (36) are clearance-fitted. The short central tube (36) is fitted with a lower cone (17) at the lower part of the upper cone (14). The lower cone (17) is threadedly connected to the compression sleeve (19). An anchor block (15), an anchor block sleeve (16), and a lower locking cap (18) are installed on the outer side of the opposite ends of the lower cone (17) and the upper cone (14). The short central tube (36) is connected to the rubber sleeve core tube (25) by a threaded connection in the middle outer circle, and the lower part of the rubber sleeve core tube (25) is connected to the lower connector (26) by a threaded connection. A radially expandable rubber sleeve assembly is fitted on the rubber sleeve core tube (25) between the upper end of the lower connector (26) and the lower end of the compression sleeve (19). The lower end of the lower connector (26) is threadedly connected to the ash injection head (30), and the ash injection head (30) is equipped with a one-way valve assembly that can only discharge downwards; The lower part of the long central tube (6) is connected to the sealing short section (33) by a drop scissor pin (35). The sealing short section (33) and the short central tube (36) are fitted with a sealing ring through a gap. The sealing short section (33) is fixedly connected to the short central tube (36) by a first pin (34). The lower inner hole of the sealing short section (33) is connected to the ball-throwing seat (31) through a channel scissor pin (32) and a sealing ring. The upper part of the short central tube (36) is fixedly connected to the unsealing head (10) by the second pin (38). The lower part of the short central tube (36) is connected to the thrust seat (13) by the unsealing shear pin (37). The thrust seat (13) has a limiting ring groove machined on the outside. A thrust ring (12) is installed in the limiting ring groove. A one-way toothed ring (1201) is machined on the outer circle of the thrust ring (12). A one-way toothed hole (901) that can mesh with the one-way toothed ring (1201) is machined on the upper part of the inner hole of the compression cylinder (9).

2. The cement retainer according to claim 1, characterized in that: The thrust ring (12) is made of elastic material. A notch (1202) is opened on one side of the tube wall of the thrust ring (12). The unsealing shear pin (37) supports the thrust ring (12) to expand, so that the one-way toothed ring (1201) is in an elastic meshing position with the one-way toothed hole (901) of the compression cylinder (9). The short center tube (36) has an unsealing ring groove (3601) machined on the lower part of the thrust ring (12). The unsealing head (10) is provided with an outer step sleeve (1003) at the lower part. The claw joint (8) is provided with an inner step sleeve (802) at the upper part. The inner step sleeve (802) is clearance-fitted with the unsealing head (10). The outer step sleeve (1003) is clearance-fitted with the inner hole of the claw joint (8). During installation, a distance is left between the inner step sleeve (802) and the outer step sleeve (1003).

3. The cement retainer according to claim 1, characterized in that: The elastic claw (7) has an inner protruding ring (701) at its lower end and an outer protruding ring (801) at the upper part of the claw connector (8). The inner protruding ring (701) is locked in the lower part of the outer protruding ring (801). The elastic claw (7) has circumferentially distributed slits (702) that cut upwards from the bottom.

4. The cement retainer according to claim 1, characterized in that: The upper part of the unsealing head (10) is machined with an external retrieval thread (1001) and an internal retrieval thread (1002).

5. The cement retainer according to claim 1, characterized in that: The lower part of the rubber sleeve core tube (25) is horizontally welded with a limiting shaft (39), and the lower connector (26) is connected to the protective sleeve (27) by an outer thread. The protective sleeve (27) is made of nylon material.

6. The cement retainer according to claim 1, characterized in that: The upper connector (1) is threaded onto the upper part of the sealing sleeve (3) with a locking cap (2).

7. The cement retainer according to claim 1, characterized in that: The upper part of the ash injection head (30) is connected to the valve ball (28) by a compression spring. The lower connector (26) is connected to the valve seat (29) on the upper part of the valve ball (28) by a sealing ring and threads. The ash injection head (30) has a through-flow groove (3001) that runs vertically through it. The valve seat (29), the valve ball (28) and the compression spring together form the one-way valve assembly that can only discharge downwards.

8. The cement retainer according to claim 1, characterized in that: The rubber sleeve core tube (25) is fitted with a lower rubber sleeve (24), a spacer ring B (23), a middle rubber sleeve (22), a spacer ring A (21), and an upper rubber sleeve (20) in sequence from bottom to top above the lower connector (26). The upper rubber sleeve (20) is positioned at the lower end of the compression sleeve (19). The lower rubber sleeve (24), the spacer ring B (23), the middle rubber sleeve (22), the spacer ring A (21), and the upper rubber sleeve (20) together constitute the rubber sleeve assembly.

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