Double-sealed self-locking cementing plug

Abstract

This utility model relates to the field of cementing plug technology and discloses a double-sealed self-locking cementing plug, comprising: a plug mandrel, a plug sleeve fitted on the outer wall of the plug mandrel, a protruding structure on the outer side of the plug sleeve, and two protrusions on the protruding structure away from the plug mandrel, the two protrusions having opposite inclination directions, and an expansion passage between the plug mandrel and the plug sleeve. In this double-sealed self-locking cementing plug, some liquid medium flows into the interior of the horizontal hole through the vertical hole and the first protrusion, accumulating more and more medium inside the horizontal hole. Some medium flows into the interior of the cavity through the second protrusion, increasing the pressure of the medium entering the cavity, which in turn causes the plug sleeve to expand to a certain extent. This increases the clamping force against the inner wall of the casing to compensate for reduced sealing due to wear of the protruding structure, thus improving durability.

Description

Technical Field

[0001] This utility model relates to the field of cementing plug technology, specifically a double-sealed self-locking cementing plug. Background Technology

[0002] Cementing plugs are key tools used in cementing operations during oil and gas drilling. Their core function is to ensure stable flow of cement slurry between the wellbore and casing through isolation, scraping, and pressing operations, preventing contamination and improving cementing quality, while also protecting the oil and gas reservoir and extending the well's service life. In oil and gas field cementing operations, the sealing performance of the plug, as a core component separating cement slurry from drilling fluid, directly determines the cementing quality.

[0003] Therefore, the sealing performance of cementing plugs is of paramount importance in oil and gas drilling. In order to improve the sealing performance of cementing plugs, the utility model patent with authorization announcement number CN223075518U discloses an anti-slip cementing plug, which includes a plug mandrel. Several rubber discs are axially sleeved on the plug mandrel. The outer wall of the rubber discs is provided with a protruding structure, which is used to resist the pressure at both ends of the rubber discs in the axial direction.

[0004] In the application of cementing plugs, although these plugs can achieve good sealing effects, effectively prevent cross-contamination, and avoid backflow, their sealing performance inevitably decreases due to wear on the raised structures on both sides during long-term use. At this point, the plug cannot expand away from the plug core, thus failing to increase the clamping force between it and the inner wall of the casing, and cannot compensate for the reduced sealing performance. Therefore, its durability still needs further improvement. Utility Model Content

[0005] The purpose of this invention is to provide a double-sealed self-locking cementing plug that can achieve self-expansion through optimized structure. When the sealing performance is reduced due to wear of the protruding structure, it increases the clamping force against the inner wall of the casing to compensate, thereby improving durability and solving the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a double-sealed self-locking cementing plug, comprising: a plug mandrel, a plug sleeve fitted on the outer wall of the plug mandrel, a protruding structure on the outer side of the plug sleeve, two protrusions on the protruding structure away from the plug mandrel, the two protrusions having opposite inclination directions, an expansion passage between the plug mandrel and the plug sleeve, the expansion passage comprising: a pair of transverse holes, the pair of transverse holes being opened on the end face of the plug mandrel, multiple vertical holes being opened on the outer wall of the plug sleeve, a first protruding tube being inserted into the vertical holes toward the interior of the plug mandrel, the first protruding tube being fixedly connected to the plug mandrel, the first protruding tube communicating with the interior of the vertical holes and the transverse holes, multiple cavities being provided inside the plug sleeve, a second protruding tube being inserted into the cavity toward the interior of the plug mandrel, the second protruding tube being fixedly connected to the plug mandrel, the second protruding tube communicating with the interior of the cavity and the transverse holes.

[0007] Preferably, the rubber stopper mandrel has a transverse double-section structure, and the two sections of the rubber stopper mandrel are fixedly connected.

[0008] Preferably, the outer wall of the rubber stopper is bound with multiple hoop rings.

[0009] Preferably, the surface of the rubber stopper sleeve is coated with tungsten carbide.

[0010] Compared with the prior art, the beneficial effects of this utility model are as follows: This double-sealed self-locking cementing plug has the following advantages over traditional technology: The rubber plug sleeve with raised structures can withstand bidirectional pressure from cement slurry and displacement fluid during cementing operations. Its good wear resistance and bidirectional action during descent within the casing can completely scrape away residual cement slurry on the casing wall. Over long-term use, when the raised structures at both ends of the rubber plug sleeve wear down and the sealing effect decreases, some liquid medium will flow into the interior of the horizontal hole through the vertical hole and the first raised tube. As the medium accumulates inside the horizontal hole, some of it will flow into the cavity through the second raised tube. The increased pressure of the medium entering the cavity causes the rubber plug sleeve to expand to a certain extent. This increases the pressure against the casing wall to compensate for the reduced sealing performance caused by wear of the raised structures, thus improving durability. Attached Figure Description

[0011] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0012] Figure 1 This is a schematic diagram of the structure of this utility model.

[0013] In the diagram: 1. Rubber stopper mandrel, 2. Rubber stopper sleeve, 3. Protruding structure, 4. Horizontal hole, 5. First protruding tube, 6. Vertical hole, 7. Cavity, 8. Second protruding tube, 9. Hoop ring. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] Please see Figure 1 This utility model provides a technical solution: a double-sealed self-locking cementing plug, comprising: a plug mandrel 1, a plug sleeve 2 fitted on the outer wall of the plug mandrel 1, a protruding structure 3 on the outer side of the plug sleeve 2, two protrusions on the protruding structure 3 away from the plug mandrel 1, the two protrusions having opposite inclination directions, an expansion passage between the plug mandrel 1 and the plug sleeve 2, the expansion passage comprising: a pair of transverse holes 4, the pair of transverse holes 4 being opened on the end face of the plug mandrel 1, multiple vertical holes 6 being opened on the outer wall of the plug sleeve 2, a first protruding tube 5 being inserted into the vertical holes 6 towards the interior of the plug mandrel 1, the first protruding tube 5 being fixedly connected to the plug mandrel 1, the first protruding tube 5 being interconnected with the interior of the vertical holes 6 and the transverse holes 4, multiple cavities 7 being provided inside the plug sleeve 2, a second protruding tube 8 being inserted into the cavity 7 towards the interior of the plug mandrel 1, the second protruding tube 8 being fixedly connected to the plug mandrel 1, the second protruding tube 8 being interconnected with the interior of the cavity 7 and the transverse holes 4.

[0016] In the specific implementation process, it is worth noting that the rubber plug mandrel 1, as the core support component of the entire cementing rubber plug, is made of high-strength alloy steel, possessing excellent pressure resistance and deformation resistance. It can withstand enormous pressure during cementing without damage, ensuring the overall stability of the rubber plug. Its rubber material allows it to fit tightly against the inner wall of the casing, effectively preventing leakage of cement slurry and displacement fluid. The two protrusions with opposite inclination directions in the raised structure can more effectively scrape the casing wall during the rubber plug's descent, removing residual cement slurry. The expansion passage between the rubber plug mandrel 1 and the rubber plug sleeve 2 allows for subsequent self-expansion of the rubber plug after wear. Expansion compensation provides a key channel. A pair of transverse holes 4 are evenly distributed on the end face of the rubber stopper spindle 1. Their diameters are precisely calculated to ensure smooth flow of liquid media while avoiding the impact on the strength of the rubber stopper spindle 1 due to excessively large hole diameters. Multiple vertical holes 6 are opened on the outer wall of the rubber stopper sleeve 2. They are reasonably distributed and fit tightly with the first convex tube 5. The first convex tube 5 is made of stainless steel. The multiple cavities 7 inside the rubber stopper sleeve 2 are optimized in size and position to effectively accumulate pressure when the media flows in. The second convex tube 8 is also made of stainless steel. Its connection design with the cavities 7 and transverse holes 4 allows the media to flow along a predetermined path, realizing the self-expansion function of the rubber stopper.

[0017] Furthermore, the rubber stopper spindle 1 has a transverse double-section structure, and the two sections of the rubber stopper spindle 1 are fixedly connected.

[0018] In the specific implementation process, it is worth noting that it facilitates the opening of the transverse hole 4 and the smooth progress of the processing operation.

[0019] Furthermore, the outer wall of the rubber stopper sleeve 2 is bound with multiple clamping rings 9.

[0020] In the specific implementation process, it is worth noting that it can significantly improve the stability between the rubber stopper sleeve 2 and the rubber stopper spindle 1.

[0021] Furthermore, the surface of the rubber stopper sleeve 2 is coated with tungsten carbide.

[0022] In the specific implementation process, it is worth noting that the tungsten carbide coating is uniformly covered on the surface of the rubber stopper sleeve 2 through an advanced spraying process, which can effectively resist the wear of particulate matter in cement slurry and displacement fluid, and extend the service life of the rubber stopper sleeve 2.

[0023] Working principle: Normal cementing operation performance: During cementing operations, the rubber plug sleeve 2 of the double-sealed self-locking cementing plug plays a crucial role. Its unique structural design features a raised structure 3, which gives the rubber plug sleeve 2 strong pressure resistance, allowing it to withstand the bidirectional pressure from cement slurry and displacement fluid. This stable bearing of bidirectional pressure ensures that the cement slurry and displacement fluid flow and distribute according to predetermined requirements during cementing, providing a solid guarantee for cementing quality. At the same time, the rubber plug sleeve 2 has excellent wear resistance. When descending along the casing, its good wear resistance allows it to maintain structural integrity during contact and friction with the casing wall, making it less prone to damage. Moreover, relying on its bidirectional force, the rubber plug sleeve 2 can completely scrape away residual cement slurry on the casing wall, effectively avoiding the adverse effects of residual cement slurry on subsequent operations and cementing quality, and ensuring the cleanliness and unobstructed flow inside the casing.

[0024] Flow path of the medium after wear: As the service life of the double-sealed self-locking cementing plug extends, the raised structures 3 at both ends of the plug sleeve 2 will inevitably wear down during long-term use. When the sealing effect of the raised structures 3 decreases due to wear, the liquid medium that was originally blocked by the seal will seek a new flow path. At this time, some of the liquid medium will flow into the interior of the horizontal hole 4 through the vertical hole 6 and the first convex tube 5. In the relatively closed space of the horizontal hole 4, the medium will continuously accumulate. As the inflow continues to increase, the medium accumulates more and more inside the horizontal hole 4. When the medium pressure in the horizontal hole 4 reaches a certain level, some of the medium will break through the resistance and flow into the interior of the cavity 7 through the second convex tube 8, starting the next stage of medium flow and pressure change process.

[0025] Self-expansion compensation and improved durability: As some of the medium flows into the cavity 7, the pressure inside the cavity 7 gradually increases with the increasing amount of medium. This pressure change becomes the key factor driving the deformation of the rubber plug sleeve 2. Under the influence of the increased pressure inside the cavity 7, the volume of the rubber plug sleeve 2 will expand to a certain extent. This expansion process is of great significance. It can automatically increase the clamping force between the rubber plug sleeve 2 and the inner wall of the casing when the sealing performance is reduced due to the wear of the protruding structure 3. Through this increase in clamping force, an effective sealing compensation mechanism is formed, which makes up for the sealing performance lost due to the wear of the protruding structure, thereby ensuring the sealing effect of the rubber plug throughout the entire service process. This self-compensation mechanism significantly improves the durability of the double-seal self-locking cementing rubber plug, enabling it to maintain good working performance for longer service time and more complex working conditions, providing strong support for the long-term stable operation of cementing operations.

[0026] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dual seal, self-locking cementing plug comprising: A rubber stopper mandrel (1), characterized in that: a rubber stopper sleeve (2) is fitted on the outer wall of the rubber stopper mandrel (1), and a protruding structure (3) is provided on the outer side of the rubber stopper sleeve (2). The protruding structure (3) has two protrusions in the direction away from the rubber stopper mandrel (1), and the two protrusions are inclined in opposite directions. An expansion passage is provided between the rubber stopper mandrel (1) and the rubber stopper sleeve (2). The expansion passage includes: a pair of transverse holes (4), the pair of transverse holes (4) being opened on the end face of the rubber stopper mandrel (1), and a plurality of vertical holes (4) being opened on the outer wall of the rubber stopper sleeve (2). 6) A first protruding tube (5) is inserted into the vertical hole (6) near the rubber stopper spindle (1). The first protruding tube (5) is fixedly connected to the rubber stopper spindle (1). The first protruding tube (5) is interconnected with the interior of the vertical hole (6) and the horizontal hole (4). The rubber stopper sleeve (2) has multiple cavities (7) inside. A second protruding tube (8) is inserted into the cavity (7) near the rubber stopper spindle (1). The second protruding tube (8) is fixedly connected to the rubber stopper spindle (1). The second protruding tube (8) is interconnected with the interior of the cavity (7) and the horizontal hole (4).

2. The dual seal, self-locking, cementing plug of claim 1, wherein: The rubber stopper mandrel (1) has a transverse double-section structure, and the two sections of the rubber stopper mandrel (1) are fixedly connected.

3. The dual seal, self-locking, cementing plug of claim 1, wherein: The outer wall of the rubber plug sleeve (2) is bound with multiple hoop rings (9).

4. The double-sealed self-locking cementing plug according to claim 1, characterized in that: The surface of the rubber stopper sleeve (2) is coated with tungsten carbide.

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