Composite tail pipe rubber plug for long tail pipe section and well cementation device

Abstract

The invention provides a composite tail pipe rubber plug for a long tail pipe section and a well cementation device, the composite tail pipe rubber plug comprises a composite tail pipe rubber plug main body, the composite tail pipe rubber plug main body is connected with a sleeve through a shear pin, and the upper end of the composite tail pipe rubber plug main body is provided with a tail pipe rubber plug entering guide head; when slurry replacement operation is carried out in drilling liner cementing construction, a drill rod rubber plug descends to the position of a conventional drilling liner rubber plug in a drilling liner hanger through a drilling tool, and the drill rod rubber plug is connected with the conventional drilling liner rubber plug and a seal to form a composite mechanism; when the composite structure moves downwards to the position of the composite tail pipe rubber plug main body, the conventional tail pipe rubber plug enters the guide head to form a secondary composite structure; and under the action of pressure in the pipe, the shear pin is broken, and the secondary composite structure reaches the position of the ball seat to complete bump pressure.

Description

Technical Field

[0001] The invention relates to a composite tail pipe rubber plug and a cementing device for a long tail pipe section, belonging to the cementing application field of the petroleum engineering industry. Background Art

[0002] In the field of liner cementing technology, drill pipe plugs are generally used to displace cement slurry sent into the drill tool, and play a role in isolating the displacement fluid from the cement slurry. When the drill pipe plug descends to the bottom end of the center tube of the liner hanger, it is combined with the conventional liner plug to form an effective sealing mechanism. The composite mechanism can continue to displace the cement slurry in the casing. When the liner plug descends in the casing, it scrapes the cement slurry on the inner wall of the casing and finally reaches the ball seat position to complete the collision and pressure.

[0003] However, as the industry continues to increase its efforts in large-displacement and ultra-deep well oil and gas exploration and development, the technology of liner cementing is being widely used in major oil fields at home and abroad. At the same time, as the well depth continues to increase, the casing length required for liner cementing is also constantly increasing. Whether the drill pipe plug and the conventional liner plug at the bottom of the liner hanger can normally observe the composite pressure change is related to the displacement efficiency of the cement slurry in the casing and the safety of the cementing construction, and also largely determines the success or failure of the cementing construction.

[0004] At present, the size of the rubber of the conventional liner plug is determined according to the size and wall thickness of the casing used in the actual on-site construction process. It generally includes components such as the plug core shaft, connector, short joint, sliding sleeve, and rubber wing pressure cap. However, the existing drill pipe plug and the conventional liner plug often fail to observe the change in composite pressure, which will affect the subsequent slurry replacement amount verification and whether the pressure can be successfully contacted, and will have a certain impact on the subsequent on-site operations.

[0005] For the existing liner cementing, a single composite structure of a drill pipe plug and a conventional liner plug is mostly used. During the slurry replacement process of liner cementing, this structure is easily affected by various factors such as circulation time, slurry replacement displacement, wellbore trajectory, etc., and it is easy to fail to observe the change in the composite pressure of the drill pipe plug and the conventional liner plug. Especially in the cementing process of a long liner section, it will lead to the inability to accurately check the slurry replacement volume in the later stage, resulting in high plugs or empty replacement. Summary of the invention

[0006] In view of the above-mentioned technical problems existing in the prior art, the present invention proposes a composite liner plug for a long liner section, which adds a group of composite liner plug devices at the appropriate position of the liner section. When no composite pressure change is observed between the drill pipe plug and the liner plug, a pressure composite change display can be added to the casing section, thereby facilitating accurate judgment of the slurry replacement volume at a later stage on site, while avoiding problems such as remaining plugs or empty replacement.

[0007] In addition, the invention also provides a well cementing device.

[0008] According to one aspect of the present invention, a composite tail pipe rubber plug for a long tail pipe section is provided, comprising: A composite tail pipe rubber plug body, wherein the composite tail pipe rubber plug body is connected to the casing through a shear pin, and a tail pipe rubber plug entry guide head is arranged at the upper end of the composite tail pipe rubber plug body; Among them, when the liner cementing construction is carried out for slurry replacement operation, the drill pipe plug descends through the drilling tool to the conventional liner plug in the liner hanger, and the drill pipe plug is connected with the conventional liner plug and the seal to form a composite structure; when the composite structure descends to the main body of the composite liner plug, the conventional liner plug enters the guide head to form a secondary composite structure; The shear pin breaks under the action of the pressure in the pipe, and the secondary composite structure reaches the ball seat position to complete the collision and pressing.

[0009] The present invention increases the secondary composite pressure change during the liner cementing process, is beneficial to increasing the pressure display of the rubber plug composite, serves as a reference for the calibration of the slurry replacement amount for liner cementing, can achieve accurate metering, and can effectively prevent problems such as plug retention and empty replacement from occurring on site.

[0010] A further improvement of the present invention is that the composite tail pipe rubber plug body comprises a rubber plug core barrel, and a plurality of rubber plug cups are arranged outside the rubber plug core barrel.

[0011] A further improvement of the present invention is that the number of the rubber plug leather cups can be increased or decreased as required, and the rubber plug leather cups are made of fluororubber.

[0012] The rubber plug cup has a conical or arc-shaped structure, and multiple layers are arranged on the rubber plug core tube. The rubber plug cup is made of fluororubber with lower swelling, has high elasticity, and can maintain high chemical stability in high temperature, high vacuum and high pressure environments.

[0013] A further improvement of the present invention is that a straightening mechanism is provided on the upper part of the plug core tube, and the shear pin is provided on the straightening mechanism; The shear pin is arranged on the straightening mechanism. The straightening mechanism is a protruding structure arranged on the circumference of the rubber plug core tube.

[0014] A further improvement of the present invention is that a pressure transmission hole is provided on the core tube of the rubber plug; The pressure transmission hole is arranged along the radial direction, and may be one or more.

[0015] The pressure transmission hole is arranged between the rubber plug cup and the straightening mechanism.

[0016] A further improvement of the present invention is that a pressure guide head is provided at the lower end of the rubber plug core tube.

[0017] A further improvement of the present invention is that a collision and pressure structure is provided on the collision and pressure guide head, and a sealing ring, an anti-rotation retaining spring and a positioning pin are provided on the collision and pressure structure.

[0018] According to another aspect of the present invention, a cementing device is provided, comprising: A pipe string, wherein a liner hanger is disposed at the upper end of the pipe string, a conventional liner rubber plug is disposed in the liner hanger, and a plurality of liner sections are disposed below the liner hanger; and A composite liner rubber plug is provided on the first or second liner arranged below the liner hanger; Wherein, the composite tail pipe rubber plug is the composite tail pipe rubber plug for the long tail pipe section.

[0019] A further improvement of the present invention is that it also includes: a drill pipe rubber plug lowered into the well through a drilling tool; The drill pipe rubber plug is combined with the conventional liner rubber plug to form a composite structure; the composite structure and the composite liner rubber plug form a secondary composite structure.

[0020] A further improvement of the present invention is that a pressure ball seat is provided at the lower part of the pipe string, and the pressure ball seat is combined with the pressure guide head at the lower end of the composite tail pipe rubber plug to achieve interlocking; A float collar and a float shoe are provided at the lower end of the pipe string.

[0021] Compared with the prior art, the advantages of the present invention are: According to the composite liner plug of the long liner section of the present invention, a group of composite liner plug devices is added at an appropriate position of the liner section (generally on the first or second liner at the lower part of the liner hanger). In the case that no composite pressure change is observed between the drill pipe plug and the liner plug, a pressure composite change display can be added to the casing section, thereby facilitating accurate judgment of the slurry replacement amount at a later stage on site and avoiding problems such as remaining plugs or empty replacement.

[0022] According to the composite tail pipe rubber plug with a long tail pipe section of the present invention, the number of rubber plug cups can be artificially increased or decreased, thereby reducing the resistance of the rubber plug cups entering the tail pipe and the strength risk of the shear pins on the rubber plug.

[0023] According to the composite liner rubber plug of the long tail pipe section of the present invention, the composite liner rubber plug enhances the scraping effect of the conventional liner rubber plug during the cementing displacement process of the long tail pipe section through the leather cup rubber plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, in which: Figure 1The figure shows a schematic structural diagram of a composite tail pipe rubber plug of a long tail pipe section according to an embodiment of the present invention; The drawings are not drawn to scale.

[0025] The meanings of the reference numerals in the accompanying drawings are as follows: 1. Pressure transmission hole, 2. Tail pipe rubber plug entering the guide head, 3. Shear pin, 4. Rubber plug leather cup, 5. Impact pressure guide head, 6. Rubber plug core tube. DETAILED DESCRIPTION

[0026] In order to make the technical solutions and advantages of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0027] In the field of liner cementing technology, drill pipe plugs are generally used to displace cement slurry sent into the drill tool, and play a role in isolating the displacement fluid from the cement slurry. When the drill pipe plug descends to the bottom end of the center tube of the liner hanger, it is combined with the conventional liner plug to form an effective sealing mechanism. The composite mechanism can continue to displace the cement slurry in the casing. When the liner plug descends in the casing, it scrapes the cement slurry on the inner wall of the casing and finally reaches the ball seat position to complete the collision and pressure.

[0028] However, as the industry continues to increase its efforts in large-displacement and ultra-deep well oil and gas exploration and development, the technology of liner cementing is being widely used in major oil fields at home and abroad. At the same time, as the well depth continues to increase, the casing length required for liner cementing is also constantly increasing. Whether the drill pipe plug and the conventional liner plug at the bottom of the liner hanger can normally observe the composite pressure change is related to the displacement efficiency of the cement slurry in the casing and the safety of the cementing construction, and also largely determines the success or failure of the cementing construction.

[0029] At present, the size of the rubber of the conventional liner plug is determined according to the size and wall thickness of the casing used in the actual on-site construction process. It generally includes components such as the plug core shaft, connector, short joint, sliding sleeve, and rubber wing pressure cap. However, the existing drill pipe plug and the conventional liner plug often fail to observe the change in composite pressure, which will affect the subsequent slurry replacement amount verification and whether the pressure can be successfully contacted, and will have a certain impact on the subsequent on-site operations.

[0030] For the existing liner cementing, a single composite structure of a drill pipe plug and a conventional liner plug is mostly used. During the slurry replacement process of liner cementing, this structure is easily affected by various factors such as circulation time, slurry replacement displacement, wellbore trajectory, etc., and it is easy to fail to observe the change in the composite pressure of the drill pipe plug and the conventional liner plug. Especially in the cementing process of a long liner section, it will lead to the inability to accurately check the slurry replacement volume in the later stage, resulting in high plugs or empty replacement.

[0031] In order to solve the above problems, the present invention proposes a composite liner plug for a long liner section, and adds a group of composite liner plug devices at appropriate positions of the liner section (generally on the first or second liner at the lower part of the liner hanger). When no composite pressure change is observed between the drill pipe plug and the liner plug, a pressure composite change display can be added to the casing section, which is conducive to accurate judgment of the slurry replacement volume at the later stage on site, and avoids problems such as remaining plugs or empty replacement.

[0032] In such Figure 1 In the embodiment shown, a composite tail pipe rubber plug for a long tail pipe section includes: A composite tail pipe rubber plug body, wherein the composite tail pipe rubber plug body is connected to the casing through a shear pin 3, and a tail pipe rubber plug entry guide head 2 is arranged at the upper end of the composite tail pipe rubber plug body; Among them, when the liner cementing construction is carried out for slurry replacement operation, the drill pipe plug descends through the drilling tool to the conventional liner plug in the liner hanger, and the drill pipe plug is connected with the conventional liner plug and the seal to form a composite structure; when the composite structure descends to the main body of the composite liner plug, the conventional liner plug enters the guide head to form a secondary composite structure; Under the action of the pressure in the pipe, the shear pin 3 breaks, and the secondary composite structure reaches the ball seat position to complete the collision and pressing.

[0033] The composite liner plug for the long liner section described in this embodiment increases the secondary composite pressure change during the liner cementing process, which is beneficial to increase the pressure display of the plug composite, serves as a reference for the calibrating of the slurry replacement amount for liner cementing, can achieve accurate metering, and can effectively prevent problems such as plug retention and empty replacement from occurring on site.

[0034] In one embodiment, the composite tail pipe rubber plug body includes a rubber plug core barrel 6 . The rubber plug core barrel 6 is a cylindrical structure with a central hole in the middle and a rubber plug cup 4 disposed on the outside.

[0035] The rubber plug cup 4 is a conical or arc-shaped structure, and multiple layers are arranged on the rubber plug core tube 6. In this embodiment, the rubber plug cup is made of fluororubber with lower swelling property, which has high elasticity and can maintain high chemical stability in high temperature, high vacuum and high pressure environment.

[0036] When the composite structure formed by connecting the drill pipe rubber plug described in this embodiment with the conventional liner rubber plug is connected with the composite liner rubber plug for the long liner section described in this embodiment to form a secondary composite structure, a total of eight groups of rubber structures (conventional and composite) of liner rubber plugs will be formed, which will greatly improve the scraping ability of the plug on the inner wall of the liner.

[0037] In one embodiment, the upper portion of the plug core tube 6 is provided with a protruding structure around it, which is supported in the sleeve to form a straightening mechanism.

[0038] Preferably, the shear pin 3 is arranged on the straightening mechanism.

[0039] In one embodiment, a pressure transmission hole 1 is provided on the plug core tube 6 .

[0040] The pressure transmission hole 1 is arranged radially, and can be one or more. In this embodiment, the pressure transmission hole 1 is arranged between the rubber plug cup 4 and the straightening mechanism.

[0041] In the composite liner plug for the long liner section according to the present embodiment, by providing the pressure transmission hole 1, the interior of the plug core tube 6 and the space between the plug core tube 6 and the casing can be connected, ensuring that the space between the plug cup 4 and the centralizer can flow fluid, ensuring that the composite liner plug can move smoothly.

[0042] In one embodiment, a pressure guide head 4 is provided at the lower end of the plug core tube 6 .

[0043] Preferably, the impact-pressure guide head 4 is provided with an impact-pressure structure, and the impact-pressure structure is provided with a sealing ring, an anti-rotation retaining spring and a positioning pin. The pressure-impacting guide head 4 can cooperate with the pressure-impacting ball seat below. When the composite tail pipe rubber plug of this embodiment descends to the position of the pressure-impacting ball seat, the pressure-impacting guide head 4 and the pressure-impacting ball seat form a seal and interlock, and the pressure-impacting is completed, and the cementing construction is completed.

[0044] According to another aspect of the present invention, a cementing device is provided, comprising: A pipe string, wherein a liner hanger is disposed at the upper end of the pipe string, a conventional liner rubber plug is disposed in the liner hanger, and a plurality of liner sections are disposed below the liner hanger; and A composite liner rubber plug is provided on the first or second liner arranged below the liner hanger; Wherein, the composite tail pipe rubber plug is the composite tail pipe rubber plug for the long tail pipe section described in the above embodiment.

[0045] The cementing device also includes: a drill pipe rubber plug lowered into the well through the drilling tool; The drill pipe rubber plug is combined with the conventional liner rubber plug to form a composite structure; the composite structure and the composite liner rubber plug form a secondary composite structure.

[0046] In one embodiment, a pressure ball seat is provided at the lower part of the pipe string, and the pressure ball seat is combined with the pressure guide head 4 at the lower end of the composite tail pipe rubber plug to complete interlocking; A float collar and a float shoe are provided at the lower end of the pipe string.

[0047] In this embodiment, the number of rubber plug cups 4 in the composite tail pipe rubber plug can be artificially increased or decreased to reduce the resistance of the rubber plug cups 4 entering the tail pipe and the strength risk of the shear pins 3 on the rubber plug.

[0048] The cup rubber plug and composite liner rubber plug enhance the scraping effect of conventional liner rubber plug during cementing replacement of long liner section. The composite liner plug increases the secondary composite pressure change during the liner cementing process, which is beneficial to increase the pressure display of the plug composite. It plays a reference role in the verification of the slurry replacement amount for liner cementing. While achieving accurate measurement, it can effectively prevent problems such as plug retention and empty replacement on site.

[0049] Example 1 A composite tail pipe rubber plug for a long tail pipe section, comprising: A composite tail pipe rubber plug body, wherein the composite tail pipe rubber plug body is connected to the casing through a shear pin 3, and a tail pipe rubber plug entry guide head 2 is arranged at the upper end of the composite tail pipe rubber plug body; The composite tail pipe rubber plug body includes a rubber plug core barrel 6, which is a cylindrical structure with a central hole in the middle and a rubber plug cup 4 arranged on the outside. The rubber plug cup 4 is a conical or arc-shaped structure, with multiple layers arranged on the rubber plug core barrel 6. The plug cup is made of fluororubber with lower swelling, has high elasticity, and can maintain high chemical stability in high temperature, high vacuum and high pressure environments.

[0050] Among them, when the liner cementing construction is carried out for slurry replacement operation, the drill pipe plug descends through the drilling tool to the conventional liner plug in the liner hanger, and the drill pipe plug is connected with the conventional liner plug and the seal to form a composite structure; when the composite structure descends to the main body of the composite liner plug, the conventional liner plug enters the guide head to form a secondary composite structure; Under the action of the pressure in the pipe, the shear pin 3 breaks, and the secondary composite structure reaches the ball seat position to complete the collision and pressing.

[0051] The composite liner plug for the long liner section described in this embodiment increases the secondary composite pressure change during the liner cementing process, which is beneficial to increase the pressure display of the plug composite, serves as a reference for the calibrating of the slurry replacement amount for liner cementing, can achieve accurate metering, and can effectively prevent problems such as plug retention and empty replacement from occurring on site.

[0052] The upper part of the plug core tube 6 is provided with a protruding structure around it, which is supported in the sleeve to form a straightening mechanism.

[0053] Preferably, the shear pin 3 is arranged on the straightening mechanism.

[0054] The plug core tube 6 is provided with a pressure transmission hole 1, and the pressure transmission hole 1 is arranged between the plug cup 4 and the straightening mechanism.

[0055] The lower end of the plug core tube 6 is provided with a pressure guide head 4. The pressure guide head 4 is provided with a pressure structure, and the pressure structure is provided with a sealing ring, an anti-rotation retaining spring and a positioning pin. The pressure-impacting guide head 4 can cooperate with the pressure-impacting ball seat below. When the composite tail pipe rubber plug of this embodiment descends to the position of the pressure-impacting ball seat, the pressure-impacting guide head 4 and the pressure-impacting ball seat form a seal and interlock, and the pressure-impacting is completed, and the cementing construction is completed.

[0056] During installation, the pipe plug is fixed between the guide head and the shear pin 3 through the shear pin groove. The shear value of the shear pin 3 is set according to the on-site requirements and the shear pin shear test before leaving the factory. At the same time, the two ends of the device can be processed into various API standards or special buckle types (male buckle on the left end and female buckle on the right end). Before assembly, the dimensions of each unit are measured and tested. After the four groups of rubber plug cups 4 are evenly coated with high-temperature resistant sealing grease, they are installed on the rubber plug core tube 6. The rear impact structure is connected to the rubber plug core tube 6 through a threaded buckle. At the same time, the impact structure has a sealing ring, an anti-rotation retaining ring and a positioning pin. Finally, the composite tail pipe plug is fixed by the shear pin 3.

[0057] Example 2 A cementing device, comprising: A pipe string, wherein a liner hanger is disposed at the upper end of the pipe string, a conventional liner rubber plug is disposed in the liner hanger, and a plurality of liner sections are disposed below the liner hanger; and A composite liner rubber plug is provided on the first or second liner arranged below the liner hanger; Wherein, the composite tail pipe rubber plug is the composite tail pipe rubber plug for the long tail pipe section described in the above embodiment.

[0058] The cementing device further comprises: a drill pipe plug lowered into the well through a drilling tool; the drill pipe plug is combined with the conventional liner plug to form a composite structure; the composite structure and the composite liner plug form a secondary composite structure.

[0059] A pressure ball seat is provided at the lower part of the pipe string, and the pressure ball seat is combined with the pressure guide head 4 at the lower end of the composite tail pipe rubber plug to complete interlocking; A float collar and a float shoe are provided at the lower end of the pipe string.

[0060] In this embodiment, the drill tool φ149.2mm and φ177.8mm liner (wall thickness 10.36mm, liner length 3000m) are used in cementing. The rubber diameters of the composite liner plugs are designed to be 166mm, 166mm, 166mm, and 166mm, which are consistent with the rubber diameters and quantity of conventional liner plugs. The sealing surface diameter of the impact pressure structure is designed to be 126mm, which is consistent with the inner diameter of the ball seat sealing surface, and a conventional φ149.2mm drill pipe plug is used.

[0061] During the liner running process, the float shoe, float collar, impact ball seat are run in accordance with the pre-arranged pipe string sequence, the composite liner plug is connected to the first liner at the bottom of the liner hanger, and the corresponding casing buckle is fastened according to the optimal torque, the liner hanger (including the conventional liner plug) is run in, and the drilling tool is sent in.

[0062] After the liner is delivered to the designated well depth, it is fully circulated to complete the hanger sitting (hydraulic) and releasing operations (mechanical). The cement head with a φ149.2mm drill pipe plug pre-installed is connected to the wellhead for cementing operations.

[0063] After the cementing operation is completed, the drill pipe plug in the cement head is released, and the drill pipe plug descends to the conventional liner plug at the bottom of the liner hanger through the drill bit, forms a seal with the liner plug, and is interlocked through the retaining spring structure. The shear pin 3 on the conventional liner plug is sheared off by the impact force of the drill pipe plug and the pressure in the pipe (at the same time, observe whether there is a composite pressure change on the vertical pressure gauge), and the composite drill pipe plug and the conventional liner plug enter the liner and continue to descend to the composite liner connected to the first liner at the bottom of the liner hanger. At the pipe plug position, the conventional liner plug guide head and the composite liner plug enter the guide head 2 to compound and form a seal, and are interlocked through the retaining spring structure. The shear pins of the composite liner plug are sheared off by the impact force and the pressure in the pipe (at this time, the impact force of the composite drill pipe plug and the liner plug is relatively small, and it mainly depends on the pressure in the pipe. At the same time, the composite pressure change is observed on the vertical pressure gauge to check the slurry replacement amount). At this time, a total of eight groups of rubber structures (conventional and composite) liner plugs will be formed, which will greatly improve the plug's ability to scrape the inner wall of the liner.

[0064] The composite liner plug continues to move downward to the impact ball seat position, and the impact guide head 4 at the lower end of the composite liner plug forms a seal with the impact ball seat and completes interlocking, completing the impact and pressure, and the cementing construction is completed.

[0065] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0066] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0067] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] Certain terms are used throughout this specification to refer to specific system components. As will be appreciated by those skilled in the art, different names may be used to refer to the same component, and thus this specification is not intended to distinguish between components that differ only in name and not in function. References to "one embodiment" or "an embodiment" in the specification mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the invention. Therefore, the phrases "one embodiment" or "an embodiment" appearing in various places throughout the specification do not necessarily all refer to the same embodiment.

[0069] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

[0070] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and / or modifications that fall within the scope of the present invention, and changes and / or modifications made according to the embodiments of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite tail pipe rubber plug for a long tail pipe section, characterized in that: include: A composite tail pipe rubber plug body, the composite tail pipe rubber plug body being connected to the casing via a shear pin (3), and a tail pipe rubber plug entry guide head (2) being arranged at the upper end of the composite tail pipe rubber plug body; Among them, when the liner cementing construction is carried out for slurry replacement operation, the drill pipe plug descends through the drilling tool to the conventional liner plug in the liner hanger, and the drill pipe plug is connected with the conventional liner plug and the seal to form a composite structure; when the composite structure descends to the main body of the composite liner plug, the conventional liner plug enters the guide head to form a secondary composite structure; Under the action of the pressure in the pipe, the shear pin (3) breaks, and the secondary composite structure reaches the ball seat position to complete the impact pressure.

2. The composite tail pipe rubber plug for a long tail pipe section according to claim 1, characterized in that: The composite tail pipe rubber plug body comprises a rubber plug core barrel (6), and a plurality of rubber plug leather cups (4) are arranged outside the rubber plug core barrel (6).

3. The composite tail pipe rubber plug for a long tail pipe section according to claim 2, characterized in that: The number of the rubber plug leather cups (4) can be increased or decreased as required, and the rubber plug leather cups (4) are made of fluororubber.

4. The composite tail pipe rubber plug for a long tail pipe section according to claim 3, characterized in that: A straightening mechanism is provided on the upper portion of the rubber plug core tube (6), and the shear pin (3) is provided on the straightening mechanism.

5. The composite tail pipe rubber plug for a long tail pipe section according to claim 4, characterized in that: The rubber plug core tube (6) is provided with a pressure transmission hole (1).

6. The composite tail pipe rubber plug for a long tail pipe section according to claim 5, characterized in that: A pressure guide head (4) is provided at the lower end of the rubber plug core barrel (6).

7. The composite tail pipe rubber plug for a long tail pipe section according to claim 6, characterized in that: The impact-pressure guide head (4) is provided with an impact-pressure structure, and the impact-pressure structure is provided with a sealing ring, an anti-rotation retaining spring and a positioning pin.

8. A cementing device, characterized in that: include: A pipe string, wherein a liner hanger is disposed at the upper end of the pipe string, a conventional liner rubber plug is disposed in the liner hanger, and a plurality of liner sections are disposed below the liner hanger; and A composite liner rubber plug is provided on the first or second liner arranged below the liner hanger; Wherein, the composite tail pipe rubber plug is a composite tail pipe rubber plug for a long tail pipe section according to any one of claims 1 to 7.

9. The cementing device according to claim 8, characterized in that: Also includes: The drill pipe rubber plug is lowered into the well through the drilling tool; The drill pipe rubber plug is combined with the conventional liner rubber plug to form a composite structure; the composite structure and the composite liner rubber plug form a secondary composite structure.

10. The cementing device according to claim 9, characterized in that: A pressure ball seat is provided at the lower part of the pipe string, and the pressure ball seat is combined with a pressure guide head (4) at the lower end of the composite tail pipe rubber plug to achieve interlocking; A float collar and a float shoe are provided at the lower end of the pipe string.

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