Salvageable and recyclable bottom plug for ultrathin-wall expansion pipe

Abstract

The utility model discloses a salvageable and recyclable bottom plug for an ultrathin-wall expansion pipe. The salvageable and recyclable bottom plug comprises a bottom plug male connector, a supporting sleeve, a shear pin, a bottom plug seat, a first clamping spring, a positioning pin, a second clamping spring, a ball seat and a bottom plug bottom sealing seat. The bottom plug male joint is connected with the supporting sleeve through a shear pin; the bottom plug seat is provided with a first conical surface clamp spring rail, a first clamp spring is installed on the first conical surface clamp spring rail, and the opening angle of the first clamp spring is the same as the guide angle of the first conical surface clamp spring rail. One end of the positioning nail is located in the guide groove of the supporting sleeve, and the other end is in threaded connection with the threaded hole of the bottom plug seat; an assembly formed by the bottom plug male joint and the supporting sleeve is in threaded connection with the bottom plug seat; a second clamping spring and a ball seat are arranged in the bottom plug male connector, the opening direction of the second clamping spring is the same as the falling spherical surface direction of the ball seat, and the bottom plug bottom sealing seat is in threaded connection with the end, away from the supporting sleeve, of the bottom plug male connector. The bottom plug device can be stably and reliably used in the ultrathin-wall expansion pipe with the thickness of 3-5mm, has a high pressure-resistant grade, and effectively solves the problems that a pressure cavity is difficult to build and the strength is insufficient due to the fact that the wall thickness of the thin-wall expansion pipe is insufficient in the prior art.

Description

Technical Field

[0001] This utility model relates to the field of oil extraction technology, specifically to a retrievable and recyclable bottom plug for an ultra-thin-walled expansion pipe. Background Technology

[0002] In oilfield operations, conventional expansion tube operations rely on a combination of a bottom plug and an expansion cone to build pressure and perform expansion. Bottom plugs are mainly of two types: millable and retrievable. Regardless of the type, threads must be machined to ensure a secure connection with the expansion tube's ejection chamber. Typically, the expansion tube wall thickness is in the range of 6-7 mm, and the ejection chamber wall thickness is also 6-7 mm. Under this wall thickness condition, the ejection chamber can be machined with threads to connect with the bottom plug and possesses sufficient strength to ensure the smooth operation of the expansion process.

[0003] In the prior art, for example, patent CN103821472A discloses an expansion pipe fitting device and retrieval tool for oil and water wells. The bottom of the expansion pipe is sealed by the locking pin on the pin seat, so that the pumped liquid establishes a high pressure zone in the expansion pipe, completing the expansion construction of the expansion pipe. After the construction is completed, the bottom plug is retrieved by a special retrieval tool.

[0004] However, the situation changes significantly when the expansion tube wall thickness is reduced to 4-5 mm. After machining the threads, the remaining wall thickness of the firing chamber is only 2-3 mm. Such a thin wall thickness greatly weakens the strength and is clearly unable to withstand the stress generated during the expansion of the expansion tube. This situation makes the implementation of thin-walled expansion tubes face many challenges and significantly increases the difficulty of operation.

[0005] Another reference patent, CN105986776A, discloses a method for repairing damaged casing in oil and water wells, which can effectively repair casings with a damaged length exceeding 20m. However, it does not address how to establish a stable pressure chamber in a thin-walled expansion tube, or how to achieve the unidirectional pressure bearing and retrieval function of the snap ring bottom plug. Utility Model Content

[0006] Therefore, this utility model provides a retrievable and recyclable bottom plug for ultra-thin-walled expansion tubes to solve the above-mentioned problems in the prior art.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] According to a first aspect of the present invention, a retrievable and recyclable bottom plug for an ultra-thin wall expansion tube includes a bottom plug male connector, a support sleeve, a shear pin, a bottom plug seat, a snap ring one, a positioning pin, a snap ring two, a ball seat, and a bottom plug bottom seal seat;

[0009] The bottom plug male connector is connected to the support sleeve via the shear pin; the bottom plug seat is provided with a conical snap spring track, the snap spring is installed on the conical snap spring track, and the opening angle of the snap spring is the same as the guide angle of the conical snap spring track; one end of the positioning pin is located in the guide groove of the support sleeve, and the other end is threaded into the threaded hole of the bottom plug seat;

[0010] The bottom plug male connector is threadedly connected to the component formed by the support sleeve and the bottom plug seat; the bottom plug male connector is provided with the second retaining spring and the ball seat, the opening direction of the second retaining spring is the same as the direction of the ball seat's landing surface, and the bottom plug bottom seal seat and the end of the bottom plug male connector away from the support sleeve are threadedly connected.

[0011] Furthermore, one end of the bottom plug seat is disposed between the bottom plug male connector and the support sleeve, and the bottom plug seat and the bottom plug male connector are threadedly connected.

[0012] Furthermore, it also includes a sealing ring, and the bottom plug has a groove at the end away from the support sleeve. The groove is opened along the circumference of the bottom plug, and the sealing ring is sleeved in the groove.

[0013] Furthermore, it also includes an expansion cone and a retaining spring positioning groove. The expansion cone is pre-installed inside the thin-walled expansion tube, and the bottom plug is installed at the rear end of the expansion cone. The inner wall of the thin-walled expansion tube is provided with the retaining spring positioning groove, and the retaining spring abuts against the retaining spring positioning groove.

[0014] Furthermore, the wall thickness of the thin-walled expansion tube is 3~5mm.

[0015] Furthermore, the depth of the positioning groove of the snap ring is 0.5~1.5mm.

[0016] Furthermore, the outer diameter of the expansion cone is clearance-fitted with the inner diameter of the thin-walled expansion tube, with a clearance value of 0.1~0.3mm.

[0017] This utility model has the following advantages:

[0018] This invention's bottom plugging device can be used stably and reliably in ultra-thin-walled expansion tubes with a thickness of 3-5mm, and possesses a high pressure resistance rating, effectively solving the problems of insufficient pressure chamber establishment and insufficient strength caused by insufficient wall thickness in existing thin-walled expansion tubes. Due to the ball seat installed inside the bottom plug male connector, the device has a recyclable well-washing function. During oil extraction, this function allows for well cleaning operations, effectively maintaining the well environment and improving extraction efficiency and quality. After construction, the bottom plugging device can be retrieved and recovered. The shear pin structure between the retaining spring and the support sleeve facilitates the retrieval operation. After testing and maintenance, the recovered bottom plugging device can be reused in subsequent oil extraction operations, significantly reducing production costs and improving resource utilization. A conical retaining spring track is provided on the bottom plug seat, allowing the retaining spring to expand and contract on this conical guide rail. Utilizing the guiding effect of the conical surface, the retaining spring can accurately adjust its state under different working conditions, effectively cooperating with the retaining spring positioning groove on the inner wall of the thin-walled expansion tube. The snap ring has a tapered surface that aligns with the guide rail, ensuring smooth movement along the guide rail. A shear pin connects the bottom plug male connector and the support sleeve, providing a secure connection during installation. During subsequent retrieval operations, when the snap ring pushes the support sleeve, it cuts the shear pin, causing the snap ring to retract and successfully complete the retrieval. This design ensures structural stability during installation and provides a convenient operating method for retrieval. The bottom plug male connector contains a ball seat and a ball-catching snap ring. Soluble balls or steel balls entering the ball seat are effectively captured by the ball-catching snap ring. This allows the device to successfully capture steel balls and establish stable pressure even in complex conditions such as horizontal wells, greatly expanding its application scenarios and adaptability. Attached Figure Description

[0019] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0020] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model.

[0021] Figure 1 A schematic diagram of a retrievable and recyclable bottom plug for an ultrathin-walled expansion tube, provided for some embodiments of this utility model. Figure 1 .

[0022] Figure 2 A schematic diagram of a retrievable and recyclable bottom plug for an ultrathin-walled expansion tube, provided for some embodiments of this utility model. Figure 2 .

[0023] Figure 3 This is an initial state diagram of a retrievable and recyclable bottom plug for an ultrathin-walled expansion tube, provided for some embodiments of this utility model.

[0024] Figure 4 This diagram illustrates the working state of a retrievable and recyclable bottom plug for an ultra-thin-walled expansion tube, as provided in some embodiments of this utility model.

[0025] Figure 5 This is a retrieval state diagram of a retrievable and recyclable bottom plug for an ultra-thin-walled expansion tube, provided for some embodiments of this utility model.

[0026] In the picture:

[0027] 1. Bottom plug male connector; 2. Support sleeve; 3. Shear pin; 4. Bottom plug seat; 5. Snap ring one; 6. Positioning pin; 7. Snap ring two; 8. Ball seat; 9. Bottom plug bottom seal seat; 10. Expansion cone; 11. Thin-walled expansion tube; 12. Sealing ring; 13. Soluble ball; 14. Snap ring one positioning groove. Detailed Implementation

[0028] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] like Figures 1 to 5As shown, an ultra-thin-walled expansion tube 11 with a retrievable and recyclable bottom plug according to the first aspect embodiment of this utility model includes a bottom plug male connector 1, a support sleeve 2, a shear pin 3, a bottom plug seat 4, a snap ring 5, a positioning pin 6, a snap ring 7, a ball seat 8, and a bottom plug bottom seal seat 9. The bottom plug male connector 1 is connected to the support sleeve 2 by the shear pin 3. The bottom plug seat 4 is provided with a conical snap ring 5 track, and the snap ring 5 is installed on the conical snap ring 5 track, with the opening angle of the snap ring 5 being the same as the guiding angle of the conical snap ring 5 track. One end of the positioning pin 6 is located in the guide groove of the support sleeve 2, and the other end is threaded into the threaded hole of the bottom plug seat 4. The component formed by the bottom plug male connector 1 and the support sleeve 2 is threadedly connected to the bottom plug seat 4. The bottom plug male connector 1 is provided with a snap ring 7 and a ball seat 8, with the opening direction of the snap ring 7 being the same as the direction of the ball seat 8's landing surface. The bottom plug bottom seal seat 9 is threadedly connected to the end of the bottom plug male connector 1 away from the support sleeve 2. One end of the bottom plug 4 is located between the bottom plug male connector 1 and the support sleeve 2, and the bottom plug 4 and the bottom plug male connector 1 are threaded together. A groove is provided at the end of the bottom plug 4 away from the support sleeve 2. The groove is opened along the circumference of the bottom plug 4, and a sealing ring 12 is fitted inside the groove.

[0030] In use, connect the bottom plug male connector 1 and the support sleeve 2 using shear pins 3. Place the snap ring 5 on the conical snap ring 5 track of the bottom plug seat 4, with the angle of snap ring 5 matching the angle of the guide rail. Use positioning pins 6 to position the support sleeve 2 and the bottom plug seat 4, with one end of the positioning pin 6 located in the guide groove of the support sleeve 2 and the other end screwed into the threaded hole of the bottom plug seat 4. Thread the assembly consisting of the bottom plug male connector 1 and the support sleeve 2 to the bottom plug seat 4, screwing it in clockwise. Install snap ring 7 and ball seat 8 together into the bottom plug male connector 1, with the opening of snap ring 7 aligned with the direction of the ball seat 8's landing surface. Thread the bottom plug bottom seal 9 to the bottom plug male connector 1. Insert the expansion cone 10 into the 3-5mm thick thin-walled expansion tube 11. Finally, install the assembled bottom plug assembly behind the expansion cone 10 inside the thin-walled expansion tube 11. After the bottom plug seat 4 presses against the expansion cone 10, use pipe wrenches to tighten the bottom plug male connector 1 clockwise. The bottom plug male connector 1, along with the support sleeve 2, moves towards the snap ring 5. The snap ring 5 is opened by the guide rail on the bottom plug male connector 1 and sits in the snap ring positioning groove 14 reserved in the thin-walled expansion tube 11. The depth of the snap ring positioning groove 14 is 0.5-1.5mm. After the snap ring 5 is in place, continue to tighten the positioning pin 6 into the positioning groove on the bottom plug seat 4 to prevent the bottom plug seat 4 from coming loose from the bottom plug male connector 1. The bottom plug installation is complete. The assembled thin-walled expansion tube 11 assembly is lowered into the location to be subsidized using tubing. The tubing is used for forward circulation well cleaning. After well cleaning, the soluble ball 13 is inserted and pumped into the bottom plug ball seat 8 to establish a pressure system and complete the expansion operation. Finally, a 2.7-inch externally thickened split-type retrieval spear is inserted into the bottom plug seat 4 and engaged with it. After successful engagement, the tubing string is lifted. Under the action of the expansion tube retainer spring positioning groove 14 and retainer spring 5, retainer spring 5 pushes the support sleeve 2 to cut the shear pin 3 on the support sleeve 2 and the bottom plug male connector 1. At this time, retainer spring 5 retracts under the action of the guide rail, the retainer spring 5 groove of the thin-walled expansion tube 11 loses its restraining effect, and the bottom plug is retrieved along with the tubing string.

[0031] Although the present invention has been described in detail above with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

[0032] The terms "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity of description and are not intended to limit the scope of implementation of this utility model. Any changes or adjustments to their relative relationships, without substantially altering the technical content, shall also be considered within the scope of implementation of this utility model.

Claims

1. A retrievable and recyclable bottom plug for an ultrathin-walled expansion tube, characterized in that, Includes bottom plug male connector (1), support sleeve (2), shear pin (3), bottom plug seat (4), snap ring one (5), positioning pin (6), snap ring two (7), ball seat (8) and bottom plug bottom seal seat (9); The bottom plug male connector (1) is connected to the support sleeve (2) through the shear pin (3); the bottom plug seat (4) is provided with a conical snap ring track, the snap ring (5) is installed on the conical snap ring track, and the opening angle of the snap ring is the same as the guide angle of the conical snap ring track; one end of the positioning pin (6) is located in the guide groove of the support sleeve (2), and the other end is threaded into the threaded hole of the bottom plug seat (4); The bottom plug male connector (1) and the support sleeve (2) form an assembly and are threadedly connected to the bottom plug seat (4); the bottom plug male connector (1) is provided with the snap ring 2 (7) and the ball seat (8), the opening direction of the snap ring 2 (7) is the same as the direction of the ball landing surface of the ball seat (8), and the bottom plug bottom seal seat (9) and the bottom plug male connector (1) are threadedly connected at the ends away from the support sleeve (2).

2. A fishable and retrievable bottom plug for ultra-thin wall expansion pipe according to claim 1, characterized in that, One end of the bottom plug seat (4) is disposed between the bottom plug male connector (1) and the support sleeve (2), and the bottom plug seat (4) and the bottom plug male connector (1) are threadedly connected.

3. The fishable and retrievable bottom plug for ultra-thin wall expansion pipe according to claim 1 or 2, characterized in that, It also includes a sealing ring (12), and the bottom plug (4) has a groove at the end away from the support sleeve (2). The groove is opened along the circumference of the bottom plug (4), and the sealing ring (12) is sleeved in the groove.

4. The fishable and retrievable bottom plug for ultra-thin wall expansion pipe according to claim 1, characterized in that, It also includes an expansion cone (10) and a snap ring positioning groove (14). The expansion cone (10) is pre-installed in the thin-walled expansion tube (11). The bottom plug (4) is installed at the rear end of the expansion cone (10). The inner wall of the thin-walled expansion tube (11) is provided with the snap ring positioning groove (14). The snap ring (5) abuts against the snap ring positioning groove (14).

5. A fishable and retrievable bottom plug for ultra-thin wall expansion pipe according to claim 4, characterized in that, The wall thickness of the thin-walled expansion tube (11) is 3~5mm.

6. A fishable and retrievable bottom plug for ultra-thin wall expansion pipe according to claim 4, characterized in that, The depth of the circlip positioning groove (14) is 0.5~1.5mm.

7. A fishable and retrievable bottom plug for ultra-thin wall expansion pipe according to claim 4, characterized in that, The outer diameter of the expansion cone (10) is clearance-fitted with the inner diameter of the thin-walled expansion tube (11), with a clearance value of 0.1~0.3mm.

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