A self-draining screen tube top cement injector

Abstract

This invention discloses a self-drilling screen pipe top cement injector, relating to the field of oil drilling engineering technology. The self-drilling screen pipe top cement injector includes a body, an inner cylinder, an expansion seal, and a sealing element. The inner cylinder is connected to the inner wall of the body via a first shear pin. A first end of the inner cylinder defines a pressure-retaining cavity with the body, and a pressure-retaining hole is also provided at the first end, which can be opened or closed. The second end of the inner cylinder can be connected to or disconnected from the external environment through the body. The expansion seal is sleeved on the body and defines an expansion sealing cavity with the outer peripheral wall of the body. The expansion sealing cavity is connected to the inner cavity of the inner cylinder via a one-way valve. The sealing element can be disposed within the body and seal the second end of the inner cylinder. This self-drilling screen pipe top cement injector can achieve a self-drilling effect, reducing operating costs, improving operating efficiency, and increasing the success rate of operations.

Description

Technical Field

[0001] This invention relates to the field of oil drilling engineering technology, and in particular to a self-drilling screen top cement injector. Background Technology

[0002] The horizontal well completion process with top cementing of the screen is simple to construct and has low completion costs. It can effectively seal complex upper formations and allow for the installation of pre-drilled sand control screens in the open hole of oil-bearing sections to achieve maximum drainage and effective sand control. With these advantages, this technology has become dominant in horizontal well completion operations, replacing other completion technologies.

[0003] However, after this process is completed, the inner casing of the graded hoop and blind plate remains inside the casing, which will affect the running of tools in subsequent operations. Therefore, drilling plugging is required before the well is put into production. During the drilling plugging process, there are many problems such as long drilling time for cement plugs, easy jamming, easy damage to casing and screen pipe, and easy encounter with obstacles and jamming when running the tubing string. These problems increase the drilling cycle, reduce the success rate of the process, and may even cause serious well completion accidents.

[0004] Therefore, there is an urgent need for a self-draining cement injector at the top of a screen tube to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a self-draining cement injector at the top of a screen tube, which can achieve a self-draining effect, reduce operating costs, improve operating efficiency and success rate.

[0006] To achieve the above-mentioned technical effects, the technical solution of the present invention is as follows:

[0007] A self-draining screen pipe top cement injector includes: a body; an inner cylinder connected to the inner wall of the body via a first shear pin, a first end of the inner cylinder defining a pressure-retaining cavity with the body, the first end also having a pressure-retaining hole that can be opened or closed, and a second end of the inner cylinder being able to communicate or disconnect from the external environment through the body; an expansion seal, the expansion seal being sleeved on the body and defining an expansion seal cavity with the outer peripheral wall of the body, the expansion seal cavity communicating with the inner cavity of the inner cylinder via a one-way valve; and a sealing element, the sealing element being able to be disposed within the body and seal the second end of the inner cylinder.

[0008] Furthermore, the body is provided with an adjustment cavity, a first circulation hole, and a second circulation hole. The first circulation hole is used to connect the adjustment cavity and the inner cavity, and the second circulation hole is used to connect the adjustment cavity and the external environment. The self-draining screen tube top cement injector also includes: an opening member, which is connected to the inner wall of the adjustment cavity by a second shear pin, and the opening member can open the first circulation hole and the second circulation hole; and a closing member, which is connected to the inner wall of the adjustment cavity by a third shear pin, and the closing member can close the first circulation hole and the second circulation hole.

[0009] Furthermore, the inner cylinder is also provided with a third circulation hole, which is connected to the first circulation hole.

[0010] Furthermore, the self-draining screen tube top cement injector also includes a sealing element, which is disposed on the inner wall of the inner cylinder, and one end of the sealing element can close the pressure hole under pressure.

[0011] Furthermore, the sealing element includes: a base, one end of which can extend into the second end; and a sealing body, which is sleeved on the other end of the base and is used to mate with the end face of the second end and seal the second end.

[0012] Furthermore, the one-way valve includes: a valve body, wherein a first inlet hole is provided at one end of the valve body facing the inner cylinder, and an outlet hole is provided at one end of the valve body facing the expansion sealing cavity; and a first valve stem, wherein the first valve stem passes through the valve body and is offset from the outlet hole, and the end of the first valve stem near the first inlet hole can close the first inlet hole.

[0013] Furthermore, the sealing component includes: a support portion disposed inside the inner cylinder, the support portion having a second liquid inlet hole; and a second valve stem passing through the support portion and offset from the second liquid inlet hole, the end of the second valve stem near the pressure-blocking hole being able to close the pressure-blocking hole.

[0014] Furthermore, the body includes: a connector assembly, the inner cylinder being disposed within the connector assembly; and an outer cylinder being sleeved on the connector assembly and defining the adjustment cavity between the outer cylinder and the connector assembly.

[0015] Furthermore, the main body is also provided with a closing hole, which connects the main body and the adjustment cavity. The closing component includes: a closing cylinder, which is connected to the main body through the third shear pin and is correspondingly disposed with respect to the closing hole; and a closing sleeve, which is sleeved on the main body and located at the end of the closing cylinder, and the closing sleeve can close the first circulation hole and the second circulation hole under the action of the closing cylinder.

[0016] Furthermore, the expansion seal includes: a flexible cylinder sleeved on the body; and a reinforcing structure disposed within the flexible cylinder.

[0017] The beneficial effects of this invention are as follows:

[0018] According to the self-drilling screen top cement injector of the present invention, the top annulus of the main body is effectively sealed during the completion operation of the screen pipe in oil and gas wells, and the inner cylinder can be detached by itself. Thus, while ensuring the normal operation of cement injection by the self-drilling screen top cement injector, the existing cement plug drilling operation is reduced. It can not only protect the inner wall of the main body, but also save operating costs, shorten the operation cycle, and protect the sealing of the top cement ring.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] Figure 1 This is one of the structural schematic diagrams of the self-draining screen tube top cement injector provided in a specific embodiment of the present invention;

[0021] Figure 2 yes Figure 1 A magnified view of the structure at point A in the middle;

[0022] Figure 3 yes Figure 1 A magnified view of the structure at point B in the middle;

[0023] Figure 4 This is the second schematic diagram of the structure of the self-draining screen tube top cement injector provided in a specific embodiment of the present invention;

[0024] Figure 5 yes Figure 4 A magnified schematic diagram of the structure at point C.

[0025] Figure Labels

[0026] 1. Body; 11. Adjustment chamber; 12. First circulation hole; 13. Second circulation hole; 14. Connector assembly; 141. Upper connector; 142. Lower connector; 15. Outer cylinder; 16. Closing hole;

[0027] 2. Inner cylinder; 21. Pressure relief hole; 22. Third circulation hole;

[0028] 31. First shear pin; 32. Second shear pin; 33. Third shear pin;

[0029] 41. Expansion seal; 411. Flexible cylinder; 412. Fixing sleeve;

[0030] 42. Expansion sealing cavity;

[0031] 43. One-way valve; 431. Valve body; 4311. First inlet port; 4312. Outlet port; 432. First valve stem; 433. First elastic element;

[0032] 5. Seal; 51. Substrate; 52. Sealing body; 521. Sealing wing;

[0033] 61. Opening component; 62. Closing component; 621. Closing cylinder block; 622. Closing sleeve;

[0034] 7. Sealing component; 71. Support part; 711. Second liquid inlet; 72. Second valve stem; 73. Second elastic component. Detailed Implementation

[0035] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0036] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0038] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of the invention, unless otherwise stated, "a plurality of" means two or more. Furthermore, the terms "first" and "second" are only used for descriptive distinction and have no special meaning.

[0039] The following is for reference. Figures 1-5 The specific structure of the self-draining screen tube top cement injector according to an embodiment of the present invention is described.

[0040] like Figures 1-5 As shown, Figure 1 A self-draining cement injector for top-filling a screen pipe is disclosed, comprising a body 1, an inner cylinder 2, an expansion seal 41, and a sealing element 5. The inner cylinder 2 is connected to the inner wall of the body 1 via a first shear pin 31. A pressure-retaining cavity is defined at the first end of the inner cylinder 2 and the body 1, and a pressure-retaining hole 21 is also provided at the first end. The pressure-retaining hole 21 can be opened or closed. The second end of the inner cylinder 2 can be connected to or disconnected from the external environment through the body 1. The expansion seal 41 is sleeved on the body 1 and defines an expansion seal cavity 42 with the outer peripheral wall of the body 1. The expansion seal cavity 42 is connected to the inner cavity of the inner cylinder 2 via a one-way valve 43. The sealing element 5 can be disposed inside the body 1 and seal the second end of the inner cylinder 2.

[0041] Understandably, after the cement injector at the top of the self-drilling screen pipe is lowered to its designed position with the well completion device, the operator slowly circulates the drilling fluid from the wellhead and closes the pressure choke hole 21. This causes the pressure inside the main body 1 and the inner cylinder 2 to gradually increase, allowing the drilling fluid to enter the expansion sealing chamber 42 from the inner cavity of the inner cylinder 2 through the one-way valve 43 and force the expansion sealing element 41 to expand. This causes the expansion sealing element 41 to fit against the well wall, achieving a better sealing annulus effect. Furthermore, the drilling fluid and the expansion sealing chamber 42 are connected through the one-way valve 43, which can effectively prevent the drilling fluid from flowing back during sealing and causing the expansion sealing element 41 to shrink back, resulting in a poor seal. This further ensures the reliability of the seal.

[0042] Subsequently, when the pressure inside the main body 1 reaches the opening pressure value, the second end of the inner cylinder 2 connects to the external environment through the main body 1, causing the pressure inside the main body 1 to drop, and enabling the operator to perform drilling fluid circulation and well washing and cementing slurry injection operations inside the main body 1 and the inner cylinder 2.

[0043] After the cement grouting operation is completed, the second end of the inner cylinder 2 is sealed by the sealing element 5. At this time, the sealing element 5 blocks the liquid flow channel, and at the same time, the second end of the inner cylinder 2 is disconnected from the external environment, so that the pressure in the area between the sealing element 5 and the wellhead gradually increases. As the pressure gradually increases, the thrust of the sealing element 5 on the inner cylinder 2 will also increase. When the pressure of the sealing element 5 on the inner cylinder 2 is greater than the shearing force of the first shear pin 31, the inner cylinder 2 will be disconnected from the body 1. At this time, if the pressure is further increased, the sealing element 5 will cause the inner cylinder 2 to fall out of the body 1, thus realizing the self-draining function of the cement injector at the top of the self-draining screen pipe.

[0044] According to the self-drilling screen top cement injector of this embodiment, the top annulus of the main body 1 is effectively sealed during the completion operation of the screen pipe in oil and gas wells, and the inner cylinder 2 can be detached by itself. Thus, while ensuring the normal operation of cement injection by the self-drilling screen top cement injector, the existing cement plug drilling operation is reduced. It can not only protect the inner wall of the main body 1, but also save operating costs, shorten the operation cycle, and protect the sealing of the top cement ring.

[0045] It should be noted that in this embodiment, the second end of the inner cylinder 2 is closer to the wellhead than the first end.

[0046] In some embodiments, such as Figures 1-5 As shown, the main body 1 is provided with an adjustment cavity 11, a first circulation hole 12, and a second circulation hole 13. The first circulation hole 12 is used to connect the adjustment cavity 11 and the inner cavity, and the second circulation hole 13 is used to connect the adjustment cavity 11 and the external environment. The cement injector at the top of the self-draining screen pipe also includes an opening member 61 and a closing member 62. The opening member 61 is connected to the inner wall of the adjustment cavity 11 by a second shear pin 32, and the opening member 61 can open the first circulation hole 12 and the second circulation hole 13. The closing member 62 is connected to the inner wall of the adjustment cavity 11 by a third shear pin 33, and the closing member 62 can close the first circulation hole 12 and the second circulation hole 13.

[0047] Understandably, during the construction of the cement injector at the top of the self-drilling screen pipe, when the pressure inside the body 1 reaches the opening pressure value, the drilling fluid in the inner cavity flows into the regulating chamber 11 through the first circulation hole 12. When the pressure on the opening member 61 exceeds the shearing force of the second shear pin 32, the drilling fluid can drive the opening member 61 to move within the regulating chamber 11 and connect the first circulation hole 12 and the second circulation hole 13, thereby achieving communication between the inner cavity and the external environment. After the second end of the inner cylinder 2 is sealed by the sealing member 5, the drilling fluid no longer enters the inner cavity of the inner cylinder 2 and will not flow into the external environment. At this time, the drilling fluid applies pressure to the closing member 62 through the regulating chamber 11. When the pressure on the closing member 62 exceeds the shearing force of the third shear pin 33, the drilling fluid can drive the closing member 62 to close the first circulation hole 12 and the second circulation hole 13, thereby disconnecting the second end of the inner cylinder 2 from the external environment.

[0048] In some embodiments, such as Figure 3 and Figure 5 As shown, the inner cylinder 2 is also provided with a third circulation hole 22, which is connected to the first circulation hole 12.

[0049] It is understandable that by opening the third circulation hole 22, it is convenient to connect the inner cavity of the inner cylinder 2 with the first circulation hole 12, thereby facilitating the opening and closing of the first circulation hole 12 and the second circulation hole 13 through the opening member 61 and the closing member 62.

[0050] In some embodiments, such as Figures 1-5 As shown, the cement injector at the top of the self-draining screen tube also includes a sealing element 7, which is located on the inner wall of the inner cylinder 2. One end of the sealing element 7 can close the pressure hole 21 under pressure.

[0051] It is understandable that by setting the plug 7, it is easy to close the pressure-blocking hole 21 with drilling fluid, thereby realizing the pressure-blocking function.

[0052] In some embodiments, such as Figure 3 and Figure 5 As shown, the seal 5 includes a base 51 and a sealing body 52. ​​One end of the base 51 can extend into the second end. The sealing body 52 is sleeved on the other end of the base 51, and the sealing body 52 is used to mate with the end face of the second end and seal the second end.

[0053] It is understandable that the sealing body 52 can effectively achieve the sealing effect of the sealing element 5 on the second end of the inner cylinder 2, while the base 51 can effectively improve the strength of the sealing body 52.

[0054] In some specific embodiments, such as Figure 3As shown, the outer peripheral wall of the sealing body 52 is provided with a plurality of sealing rubber wings 521, which can further improve the sealing effect between the sealing body 52 and the inner wall of the body 1.

[0055] In some embodiments, such as Figure 2 As shown, the one-way valve 43 includes a valve body 431 and a first valve stem 432. The valve body 431 has a first inlet hole 4311 at one end facing the inner cylinder 2, and an outlet hole 4312 at the other end facing the expansion sealing cavity 42. The first valve stem 432 passes through the valve body 431 and is offset from the outlet hole 4312. The end of the first valve stem 432 near the first inlet hole 4311 can close the first inlet hole 4311.

[0056] Understandably, when the first valve stem 432 is subjected to the pressure of the drilling fluid inside the body 1, it will move towards the first inlet hole, creating a gap between the first valve stem 432 and the first inlet hole 4311. This allows the drilling fluid to flow into the valve body 431 through the first inlet hole 4311 and then into the expansion sealing chamber 42 through the outlet hole 4312. When the drilling fluid in the expansion sealing chamber 42 has a tendency to flow towards the body 1, the first valve stem 432 will move towards the first inlet hole 4311 under the action of the drilling fluid in the expansion sealing chamber 42 and close the first inlet hole 4311, thereby realizing the one-way flow function of the one-way valve 43.

[0057] In some specific embodiments, such as Figure 2 As shown, the one-way valve 43 also includes a first elastic element 433, which is sleeved on the first valve stem 432. One end of the first elastic element 433 abuts against the inner wall of the valve body 431, and the other end abuts against the end of the first valve stem 432 near the first inlet hole 4311.

[0058] Understandably, the inclusion of the first elastic element 433 facilitates the improvement of the reliability of the one-way valve 43.

[0059] Specifically, the first elastic element 433 can be configured as a spring.

[0060] In some embodiments, such as Figure 2 As shown, the sealing component 7 includes a support portion 71 and a second valve stem 72. The support portion 71 is located inside the inner cylinder 2 and has a second liquid inlet 711. The second valve stem 72 passes through the support portion 71 and is offset from the second liquid inlet 711. The end of the second valve stem 72 near the pressure-blocking hole 21 can close the pressure-blocking hole 21.

[0061] Understandably, when drilling fluid flows into the space between the support 71 and the second valve stem 72 through the second inlet hole 711, the drilling fluid can apply pressure to the second valve stem 72 and cause the second valve stem 72 to move toward the pressure-blocking hole 21, thereby causing the end of the second valve stem 72 that is close to the pressure-blocking hole 21 to close the pressure-blocking hole 21. Thereafter, under the pressure of the drilling fluid, the second valve stem 72 will remain closed to the pressure-blocking hole 21, so that the sealing member 7 can achieve a good sealing effect on the pressure-blocking hole 21.

[0062] In some specific embodiments, such as Figures 1-5 As shown, the sealing component 7 also includes a second elastic component 73, which is sleeved on the second valve stem 72. One end of the second elastic component 73 abuts against the support portion 71, and the other end abuts against the end of the second valve stem 72 away from the support portion 71.

[0063] Understandably, the second elastic element 73 is designed to improve the ease of sealing operation of the sealing element 7 under pressure.

[0064] Specifically, the second elastic element 73 can be configured as a spring.

[0065] In some embodiments, such as Figure 3 and Figure 5 As shown, the main body 1 includes a connector assembly 14 and an outer cylinder 15. The inner cylinder 2 is disposed inside the connector assembly 14. The outer cylinder 15 is sleeved on the connector assembly 14 and defines an adjustment cavity 11 between the outer cylinder 15 and the connector assembly 14.

[0066] It is understandable that the installation of the connector assembly 14 and the outer cylinder 15 can facilitate the assembly of the body 1 and the inner cylinder 2. In addition, the adjustment cavity 11 defined between the outer cylinder 15 and the connector assembly 14 can also reduce the processing difficulty of the adjustment cavity 11.

[0067] In some specific embodiments, such as Figure 2 and Figure 5 As shown, the connector assembly 14 includes an upper connector 141 and a lower connector 142.

[0068] In some embodiments, such as Figure 3 and Figure 5 As shown, the main body 1 also has a closing hole 16, which connects the inside of the main body 1 and the adjustment cavity 11. The closing component 62 includes a closing cylinder 621 and a closing sleeve 622. The closing cylinder 621 is connected to the main body 1 by a third shear pin 33 and is correspondingly positioned to the closing hole 16. The closing sleeve 622 is sleeved on the main body 1 and located at the end of the closing cylinder 621. The closing sleeve 622 can close the first circulation hole 12 and the second circulation hole 13 under the action of the closing cylinder 621.

[0069] Understandably, the design of the closing hole 16 facilitates the entry of drilling fluid into the regulating chamber 11 and the application of pressure to the closing element 62 within the regulating chamber 11. The design of the closing cylinder 621 facilitates the reliable movement of the closing sleeve 622 and the sealing of the first circulation hole 12 and the second circulation hole 13, thereby improving the sealing reliability of the first circulation hole 12 and the second circulation hole 13.

[0070] In some embodiments, such as Figure 4 As shown, the expansion seal 41 includes a flexible cylinder 411 and a reinforcing structure. The flexible cylinder 411 is sleeved on the body 1. The reinforcing structure is disposed in the flexible cylinder 411.

[0071] Understandably, the flexible cylinder 411 has good flexibility, which ensures that the flexible cylinder 411 can expand when the expansion sealing cavity 42 is filled with drilling fluid, thereby achieving a good sealing effect. The reinforcement structure can improve the robustness of the flexible structure and prevent the flexible cylinder 411 from rupturing under excessive pressure.

[0072] Specifically, in this embodiment, the flexible cylinder 411 can be configured as a rubber cylinder, and the reinforcing structure can be configured as a wire mesh embedded in the flexible cylinder 411.

[0073] In some embodiments, such as Figure 4 As shown, the expansion seal 41 also includes a fixing sleeve 412. The fixing sleeve 412 is located at one end of the flexible cylinder 411 away from the opening member 61 and the closing member 62. The fixing sleeve 412 is sleeved on the body 1 and fixedly connected to the body 1.

[0074] It is understandable that by setting the fixed sleeve 412, the sealing reliability of the expansion cavity 42 formed between the expansion seal 41 and the body 1 can be well guaranteed.

[0075] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0076] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A self-draining cement injector for the top of a screen pipe, characterized in that, include: Ontology(1); The inner cylinder (2) is connected to the inner wall of the body (1) by a first shear pin (31). The first end of the inner cylinder (2) and the body (1) define a pressure chamber. The first end is also provided with a pressure hole (21). The pressure hole (21) can be opened or closed. The second end of the inner cylinder (2) can be connected or disconnected from the external environment through the body (1). An expansion seal (41) is sleeved on the body (1) and defines an expansion seal cavity (42) with the outer peripheral wall of the body (1). The expansion seal cavity (42) is connected to the inner cavity of the inner cylinder (2) through a one-way valve (43). A sealing element (5) is provided inside the body (1) and seals the second end of the inner cylinder (2); The main body (1) is provided with an adjustment cavity (11), a first circulation hole (12), and a second circulation hole (13). The first circulation hole (12) is used to connect the adjustment cavity (11) and the inner cavity, and the second circulation hole (13) is used to connect the adjustment cavity (11) and the external environment. The self-draining screen pipe top cement injector also includes: An opening member (61) is connected to the inner wall of the adjustment cavity (11) via a second shear pin (32). The opening member (61) can open the first circulation hole (12) and the second circulation hole (13). The closing element (62) is connected to the inner wall of the adjustment cavity (11) by a third shear pin (33), and the closing element (62) can close the first circulation hole (12) and the second circulation hole (13). The self-draining screen tube top cement injector also includes a sealing element (7), which is provided on the inner wall of the inner cylinder (2). One end of the sealing element (7) can close the pressure hole (21) under pressure. The one-way valve (43) includes: The valve body (431) has a first liquid inlet hole (4311) at one end facing the inner cylinder (2) and a liquid outlet hole (4312) at the other end facing the expansion sealing cavity (42). The first valve stem (432) passes through the valve body (431) and is offset from the liquid outlet (4312). The end of the first valve stem (432) near the first liquid inlet (4311) can close the first liquid inlet (4311). The sealing element (7) includes: Support part (71), the support part (71) is provided inside the inner cylinder (2), and the support part (71) is provided with a second liquid inlet hole (711). The second valve stem (72) passes through the support part (71) and is offset from the second liquid inlet (711). The end of the second valve stem (72) near the pressure hole (21) can close the pressure hole (21).

2. The self-draining screen top cement injector according to claim 1, characterized in that, The inner cylinder (2) is also provided with a third circulation hole (22), which is connected to the first circulation hole (12).

3. The self-draining screen top cement injector according to claim 1, characterized in that, The seal (5) includes: The substrate (51) has one end that can extend into the second end; A sealing body (52) is fitted onto the other end of the base (51) and is used to mate with the end face of the second end and seal the second end.

4. The self-draining screen tube top cement injector according to claim 1, characterized in that, The body (1) includes: The connector assembly (14) is provided inside the inner cylinder (2); An outer cylinder body (15) is fitted onto the connector assembly (14) and defines the adjustment cavity (11) between the connector assembly (14).

5. The self-draining screen top cement injector according to claim 1, characterized in that, The main body (1) is also provided with a closing hole (16), the closing hole (16) is connected to the inside of the main body (1) and the adjustment cavity (11), and the closing member (62) includes: The closing cylinder (621) is connected to the main body (1) via the third shear pin (33) and is correspondingly set with the closing hole (16); The closing sleeve (622) is sleeved on the body (1) and located at the end of the closing cylinder (621). The closing sleeve (622) can close the first circulation hole (12) and the second circulation hole (13) under the action of the closing cylinder (621).

6. The self-draining screen tube top cement injector according to claim 1, characterized in that, The expansion seal (41) includes: A flexible cylinder (411) is sleeved on the body (1); A reinforcing structure is provided in the flexible cylinder (411).

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