Well cementation rubber plug for seabed oil well

Abstract

The invention discloses a well cementation rubber plug for a seabed oil well, and relates to the technical field of well cementation rubber plugs, the well cementation rubber plug comprises a first upper rubber plug, a first rotating assembly is arranged below the first upper rubber plug, a second upper rubber plug is installed below the first rotating assembly, and a first lower rubber plug is arranged below the second upper rubber plug; a first rotating assembly is arranged below the first upper rubber plug, a second rotating assembly is arranged below the first lower rubber plug, a second lower rubber plug is arranged below the second rotating assembly, a first sealing ring, a second sealing ring, a third sealing ring and a fourth sealing ring are arranged on the outer sides of the first upper rubber plug, the second upper rubber plug, the first lower rubber plug and the second lower rubber plug correspondingly, and a cavity is formed in the fourth sealing ring; a first pressing rod is installed in the second upper rubber plug, and a second pressing rod and a rupture disc are installed in the second lower rubber plug. The well cementation rubber plug solves the problems that an existing well cementation rubber plug cannot adapt to a bent section of a casing pipe and cannot accommodate a scraping and cleaning part to enhance the sealing performance after moving downwards to a proper position.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of well cementing plugs, and particularly relates to a well cementing plug for a seabed oil well. BACKGROUND

[0002] The well cementing plug is a key tool in well cementing operation of oil drilling, and the core function thereof is to isolate fluid and clean the casing to guarantee well cementing quality and wellbore safety. In the well cementing operation of the seabed oil well, the well cementing plug builds a highly sealed wellbore barrier to prevent methane leakage, realizes low-carbon production, and can not only guarantee long-term stable use of the wellbore but also significantly reduce additional energy consumption and carbon emission caused by subsequent maintenance intervention, thus providing indispensable downhole conditions for implementation of carbon capture and storage technology.

[0003] The patent with the publication number CN106958435A discloses a well cementing plug, which comprises a first body, a cavity opening downward is arranged in the first body, and a pressure part is arranged at the upper end of the body; a rotation prevention part is arranged on the inner wall of the first body, and the rotation prevention part can be connected with the cement slurry entering the cavity to limit rotation of the first plug body; a second plug body comprises a second body; a plurality of cleaning parts are arranged on the outer side wall of the first body and the second body along the length direction of the first body and the second body, and are used for scraping off residues on the inner wall of the casing. The above device can realize the function of cleaning residues, but in use, the existing well cementing plug cannot use the scraping and cleaning structure when being moved downward, and cannot use the sealing structure after being moved to a suitable position.

[0004] The patent with the publication number CN110671074B discloses a well cementing plug rubber part and a reinforcing method thereof, a wire mesh framework is implanted in the skin bowl part of the rubber part, the wire mesh framework extends out of the rubber part at the position where the skin bowl contacts the metal rod and is connected with the metal rod, wherein the wire mesh framework is a single-layer two-dimensional circular truncated cone structure or a multi-layer three-dimensional circular truncated cone structure in a grid weaving form, and the length of the wire mesh framework extending out of the rubber part is not less than half of the height of the skin bowl. The reinforcing method is to implant a wire mesh of another material as a framework in the rubber part during high-temperature forming of the plug rubber part to improve the tensile and wear resistance of the rubber part, and to firmly connect the wire mesh framework implanted in the rubber part with the metal rod of the plug to improve the anti-falling strength of the rubber part and the metal rod. The above device can improve the strength by using the wire mesh framework, but cannot adapt to the bending section of the casing. Although the existing bending structure can realize the bending function, the strength of the well cementing plug is reduced in use, and the bending function cannot be realized under the condition of ensuring the strength. SUMMARY

[0005] The present application aims at providing a cementing plug for subsea oil well to solve the problem that the existing cementing plug cannot adapt to the bent section of the casing, cannot use the scraping cleaning structure when moving down, and cannot accommodate the scraping cleaning part to enhance the sealing performance after moving down to the appropriate position.

[0006] To achieve the above object, the present application provides the following technical scheme: a cementing plug for subsea oil well, comprising a first upper plug, a first rotating assembly arranged below the first upper plug, a second upper plug mounted below the first rotating assembly, a first lower plug arranged below the second upper plug, a second rotating assembly arranged below the first lower plug, a second lower plug mounted below the second rotating assembly, a first sealing ring, a second sealing ring, a third sealing ring and a fourth sealing ring respectively mounted on the outer sides of the first upper plug, the second upper plug, the first lower plug and the second lower plug, a cavity opened in the fourth sealing ring, a first pressing rod mounted in the second upper plug, a second pressing rod and a rupture disc mounted in the second lower plug, a second spring mounted between the second pressing rod and the second lower plug, a second opening opened in the second lower plug, a pressing block and a sliding rod slidingly mounted on the second lower plug, a third spring mounted between the pressing block and the sliding rod, a scraping plate mounted on the sliding rod, and an annular groove opened in the second pressing rod.

[0007] As a further scheme of the present application, a first leaf spring and a first protective sleeve are mounted between the first lower plug and the second lower plug, and a second leaf spring and a second protective sleeve are mounted between the first upper plug and the second upper plug.

[0008] As a further scheme of the present application, the first rotating assembly comprises a first outer bushing fixedly connected to the bottom of the first upper plug, a second outer bushing fixedly connected to the second upper plug and attached to the inside of the first outer bushing, a first sealing piston fixedly connected to the second outer bushing, and a first protruding plate fixedly arranged in the first upper plug.

[0009] As a further scheme of the present application, a first moving groove is opened in the first outer bushing, a first damping sleeve used for abutting against the first pressing rod is mounted in the first moving groove, and the first pressing rod penetrates through the inside of the second outer bushing and the first sealing piston.

[0010] As a further scheme of the present application, the central axis of the rupture disc is collinear with that of the second lower plug, the rupture disc has a thickness distribution gradually increasing from the center to the edge, and a traction assembly is arranged below the rupture disc.

[0011] As a further further scheme of the present application: the traction assembly comprises an adapter plate and a guide wheel mounted on the inner wall of the second lower rubber plug, a guide rod is slidingly mounted in the adapter plate, a first spring is fixedly connected to the guide rod, a support plate is mounted on the guide rod, a traction steel cable is fixedly connected to the support plate, the traction steel cable is connected to one of the second pressure rods through the guide wheel, and a first opening is formed in the second lower rubber plug.

[0012] As a further further scheme of the present application: the support plate is provided with a notch, and the support plate is rotatably connected to the guide rod.

[0013] As a further further scheme of the present application: the second rotating assembly comprises a third outer bushing fixedly connected to the bottom of the first lower rubber plug, a fourth outer bushing is attached to the inner wall of the third outer bushing, the bottom of the fourth outer bushing is connected to the second lower rubber plug, a second sealing piston is fixedly connected to the fourth outer bushing, a second protruding plate is fixedly arranged in the first lower rubber plug, and a second moving groove is formed in the third outer bushing.

[0014] As a further further scheme of the present application: the second pressure rod penetrates into the fourth outer bushing, a second damping sleeve for butt joint with the second pressure rod is mounted in the second moving groove, and the connection mode of the second rotating assembly with the first lower rubber plug and the second lower rubber plug is the same as the connection mode of the first rotating assembly with the first upper rubber plug and the second upper rubber plug.

[0015] As a further further scheme of the present application: the second pressure rod is uniformly arranged along the circumference of the second lower rubber plug, and a connecting plate is fixedly connected between the adjacent two second pressure rods.

[0016] Compared with the prior art, the present application has the following advantages: 1. The device is provided with a pressing block, a third spring, a sliding rod and a second pressure rod. When the bottom of the second lower rubber plug moves to the bottom of the sleeve, the second pressure rod is pressed and slides in the second lower rubber plug until the position of the annular groove on the second pressure rod corresponds to the position of the pressing block. The pressing block moves into the annular groove, the third spring in the compressed state relaxes, and then the scraping plate is no longer pressed against the inner wall of the sleeve after moving to the bottom of the device, but is pressed against the inner wall of the device by the sealing ring on the device. As the second pressure rod moves upward, the air pressure in the second opening and the cavity increases, so that the fourth sealing ring is kept in a tight state with the inner wall of the sleeve. The device not only has a structure switching function, but also can increase the moving resistance by using the fourth sealing ring to tighten the inner wall of the sleeve after switching to the sealing structure, so as to ensure the stability of the whole device.

[0017] 2、The device is provided with a first rotating component and a second rotating component, and the upper and lower parts of the upper and lower rubber plugs are connected by the corresponding rotating components, so that when the rubber plug is estimated to move in the bending area, it will not be excessively squeezed, but will first rotate through the first rotating component or the second rotating component, when the second upper rubber plug rotates at the bottom of the first upper rubber plug, the second outer bushing will rotate in the first outer bushing while maintaining the sealing effect of the whole device, similarly, when the second lower rubber plug rotates at the first lower rubber plug, the fourth outer bushing will rotate in the third outer bushing while maintaining the sealing state, so that the device can be used in the bending section, solving the problem that the existing cementing rubber plug is prone to reduce the strength when bending, and cannot be bent while ensuring the strength, and the device has the advantage of stronger adaptability.

[0018] 3、The device is provided with a second pressure rod and a traction component, when the second pressure rod moves to the bottom of the device and slides in the second lower rubber plug, it will pull the support plate to rotate through the traction steel rope, the support plate will rotate above the guide rod, so that the support plate no longer plays a protective function for the rupture disc, the inclined support plate can make the rupture disc rupture by using the sharp end of the support disc, so that the rubber plug reduces its own strength after moving to the bottom of the casing, enhancing the convenience of the device when used.

[0019] 4、The device is provided with a second spring, a first damping sleeve and a second damping sleeve, when the second lower rubber plug moves to the bottom of the casing, the second pressure rod moves upward at the same time and penetrates into the inside of the fourth outer bushing, and the top of the second pressure rod is clamped with the second damping sleeve, at this time the second lower rubber plug and the first lower rubber plug are integrally sealed, so that after the device switches from the scraping structure to the sealing structure, the second rotating structure is automatically locked, when the second upper rubber plug abuts against the first lower rubber plug, the first pressure rod slides in the second upper rubber plug until it is pressed tightly with the first damping sleeve, so that the upper rubber plug and the lower rubber plug are automatically locked after abutting, enhancing the stability of the device. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present application; Figure 2 It is a schematic diagram of the connection structure of the first upper rubber plug and the second upper rubber plug of the present application; Figure 3 It is a schematic diagram of the connection structure of the first lower rubber plug and the second lower rubber plug of the present application; Figure 4 It is Figure 3 It is an enlarged schematic diagram of the structure at point A in the middle; Figure 5 It is Figure 3 It is an enlarged schematic diagram of the structure at point B in the middle; Figure 6 It is Figure 3 It is an enlarged schematic diagram of the structure at point C in the middle; Figure 7 Fig. 2 is a side view of the first lower rubber plug and the second lower rubber plug according to the present application; Figure 8 Fig. 3 is a side view of the first upper rubber plug according to the present application; Figure 7 Fig. 4 is an enlarged view of the structure at D in Fig. 3; Figure 9 Fig. 5 is a side view of the first upper rubber plug and the second spring according to the present application; Figure 10 Fig. 6 is a side view of the second lower rubber plug and the first spring according to the present application; Figure 11 Fig. 7 is a side view of the first upper rubber plug in a bent state according to the present application; Figure 12 Fig. 8 is a side view of the first lower rubber plug in a bent state according to the present application; Figure 13 Fig. 9 is a side view of the bottom structure of the support plate according to the present application; Figure 14 Fig. 10 is a side view of the second upper rubber plug according to the present application; Figure 13 Fig. 11 is an enlarged view of the structure at E in Fig. 10.

[0021] Fig. 1 is a side view of the first upper rubber plug according to the present application; Fig. 2 is a side view of the first lower rubber plug and the second lower rubber plug according to the present application; Fig. 3 is a side view of the first upper rubber plug according to the present application; Fig. 4 is an enlarged view of the structure at D in Fig. 3; Fig. 5 is a side view of the first upper rubber plug and the second spring according to the present application; Fig. 6 is a side view of the second lower rubber plug and the first spring according to the present application; Fig. 7 is a side view of the first upper rubber plug in a bent state according to the present application; Fig. 8 is a side view of the first lower rubber plug in a bent state according to the present application; Fig. 9 is a side view of the bottom structure of the support plate according to the present application; Fig. 10 is a side view of the second upper rubber plug according to the present application; Fig. 11 is an enlarged view of the structure at E in Fig. 10. 1, first upper rubber plug; 2, second upper rubber plug; 3, first lower rubber plug; 4, second lower rubber plug; 5, first sealing ring; 6, second sealing ring; 7, third sealing ring; 8, fourth sealing ring; 9, first rotating assembly; 901, first outer bushing; 902, second outer bushing; 903, first sealing piston; 904, first convex plate; 905, first moving groove; 10, first pressing rod; 11, first damping sleeve; 12, rupture disc; 13, traction assembly; 1301, engaging plate; 1302, guide rod; 1303, first spring; 1304, support plate; 1305, traction steel rope; 1306, guide wheel; 1307, first opening; 1308, notch; 14, second rotating assembly; 1401, third outer bushing; 1402, fourth outer bushing; 1403, second sealing piston; 1404, second convex plate; 1405, second moving groove; 15, second pressing rod; 16, second damping sleeve; 17, cavity; 18, second spring; 19, second opening; 20, annular groove; 21, pressing block; 22, third spring; 23, sliding rod; 24, first leaf spring; 25, first protective sleeve; 26, second leaf spring; 27, second protective sleeve; 28, connecting plate; 29, scraping plate. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0023] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance. In the description of the present application, it should be noted that unless otherwise specifically specified and limited, the terms "mounting", "connecting", "connecting", "setting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. The embodiments will be described below according to the overall structure of the present application.

[0024] Embodiment 1: As Figures 1-14As shown, the present embodiment proposes a cementing plug for subsea oil well, which comprises a first upper plug 1, a first rotating assembly 9 arranged below the first upper plug 1, a second upper plug 2 installed below the first rotating assembly 9, a first lower plug 3 arranged below the second upper plug 2, a second rotating assembly 14 arranged below the first lower plug 3, a second lower plug 4 installed below the second rotating assembly 14, the first rotating assembly 9 enabling the first upper plug 1 to rotate on the second upper plug 2, the first lower plug 3 being able to rotate on the second lower plug 4 through the second rotating assembly 14 so as to adapt to the use of the casing bending section, the first upper plug 1, the second upper plug 2, the first lower plug 3 and the second lower plug 4 being respectively provided with a first sealing ring 5, a second sealing ring 6, a third sealing ring 7 and a fourth sealing ring 8, the first sealing ring 5, the second sealing ring 6, the third sealing ring 7 and the fourth sealing ring 8 ensuring the sealing effect of the device as a whole, a cavity 17 being formed in the fourth sealing ring 8, a first pressure rod 10 being installed in the second upper plug 2, a second pressure rod 15 and a rupture disc 12 being installed in the second lower plug 4, a second spring 18 being installed between the second pressure rod 15 and the second lower plug 4, a second opening 19 being formed in the second lower plug 4, a pressure block 21 and a sliding rod 23 being slidingly installed on the second lower plug 4, a third spring 22 being installed between the pressure block 21 and the sliding rod 23, a scraping plate 29 being installed on the sliding rod 23, and an annular groove 20 being formed in the second pressure rod 15. When the second lower plug 4 moves to the bottom of the casing, the second pressure rod 15 slides in the second lower plug 4 after being pressed, which not only locks the second rotating assembly 14, but also increases the air pressure in the cavity 17 by using the second opening 19, so that the fourth sealing ring 8 is tightly pressed against the inner wall of the casing. In this process, the annular groove 20 on the second pressure rod 15 makes the pressure block 21 no longer tightly press the sliding rod 23 and the scraping plate 29 through the third spring 22, so that the scraping plate 29 is retracted while automatically expanding the fourth sealing ring 8, thereby automatically switching the scraping function to the sealing function.

[0025] Embodiment 2: The scheme in Embodiment 1 is further introduced in combination with a specific working mode, and details are described below: As Figure 7 , Figure 9 , Figure 10 , Figure 13 and Figure 14 shown, as a preferred embodiment, on the basis of the above-mentioned mode, further, the first lower plug 3 and the second lower plug 4 are provided with a first leaf spring 24 and a first protective sleeve 25, the first leaf spring 24 and the first protective sleeve 25 being able to reset after the second lower plug 4 is bent, the first upper plug 1 and the second upper plug 2 are provided with a second leaf spring 26 and a second protective sleeve 27, the second leaf spring 26 and the second protective sleeve 27 being able to reset after the second upper plug 2 is bent.

[0026] AsFigure 2 As shown, in a preferred embodiment, based on the above method, the first rotating assembly 9 further includes a first outer bushing 901 fixedly connected to the bottom of the first upper rubber plug 1, a second outer bushing 902 fitted inside the first outer bushing 901, the second outer bushing 902 being fixedly connected to the second upper rubber plug 2, a first sealing piston 903 fixedly connected to the second outer bushing 902, a first protruding plate 904 fixedly disposed inside the first upper rubber plug 1, and when the second outer bushing 902 rotates inside the first outer bushing 901, the first protruding plate 904 and the first sealing piston 903 can ensure the sealing effect of the device, and the spherical structure of the first outer bushing 901 and the second outer bushing 902 ensures that the second upper rubber plug 2 remains sealed when rotating.

[0027] like Figure 2 As shown, in a preferred embodiment, based on the above method, a first moving groove 905 is further provided in the first outer bushing 901, and a first damping sleeve 11 for docking with the first pressure rod 10 is installed in the first moving groove 905. The first pressure rod 10 passes through the interior of the second outer bushing 902 and the first sealing piston 903. When the first pressure rod 10 is pressed, it can move into the first damping sleeve 11, so that the first outer bushing 901 and the second outer bushing 902 cannot rotate relative to each other.

[0028] like Figure 3 , Figure 4 , Figure 13 and Figure 14 As shown, in a preferred embodiment, based on the above method, the central axes of the rupture disc 12 and the second lower rubber plug 4 are collinear, the rupture disc 12 has a thickness distribution that gradually increases from the center to the edge, and a traction assembly 13 is provided below the rupture disc 12. When the traction assembly 13 is not triggered, the thinner area of ​​the rupture disc 12 can be protected.

[0029] like Figure 3 , Figure 4 , Figure 6 , Figure 13 and Figure 14As shown, in a preferred embodiment, based on the above method, the traction assembly 13 further includes a connecting plate 1301 and a guide wheel 1306 installed on the inner wall of the second lower rubber plug 4. A guide rod 1302 is slidably installed in the connecting plate 1301. A first spring 1303 is fixedly connected to the guide rod 1302. A support plate 1304 is installed on the guide rod 1302. A traction steel rope 1305 is fixedly connected to the support plate 1304. The traction steel rope 1305 is guided by the guide wheel 1306 and connected to one of the second pressure rods 15. A first opening 1307 is opened in the second lower rubber plug 4. When the second pressure rod 15 is pushed upward, the traction steel rope 1305 pulls the support plate 1304 under the guidance of the guide wheel 1306. The first spring 1303 between the connecting plate 1301 and the guide rod 1302 is compressed. After the second lower rubber plug 4 moves to the bottom of the device, the support plate 1304 no longer provides protection for the rupture disc 12.

[0030] like Figure 13 and Figure 14 As shown, in a preferred embodiment, based on the above method, the support plate 1304 is further provided with a notch 1308. The support plate 1304 and the guide rod 1302 are rotatably connected. One side of the rotatably mounted support plate 1304 will rotate after being pulled, and the tip of the notch 1308 makes the rupture disc 12 easier to rupture.

[0031] like Figure 3 , Figure 5 and Figures 12-14 As shown, in a preferred embodiment, based on the above method, the second rotating assembly 14 further includes a third outer bushing 1401 fixedly connected to the bottom of the first lower rubber plug 3, a fourth outer bushing 1402 attached to the inner wall of the third outer bushing 1401, the bottom of the fourth outer bushing 1402 connected to the second lower rubber plug 4, a second sealing piston 1403 fixedly connected to the fourth outer bushing 1402, a second protruding plate 1404 fixedly disposed inside the first lower rubber plug 3, and a second moving groove 1405 opened inside the third outer bushing 1401. The spherical structure of the third outer bushing 1401 and the fourth outer bushing 1402 allows the second lower rubber plug 4 to rotate on the first lower rubber plug 3 while maintaining a sealed connection with the first lower rubber plug 3, so as to adapt to the use of the sleeve bending section. The mutually attached second sealing piston 1403 and second protruding plate 1404 ensure the sealing effect of the first lower rubber plug 3 and the second lower rubber plug 4.

[0032] like Figures 1-5As shown, as a preferred embodiment, on the basis of the above manner, further, the second pressing rod 15 is penetrated into the fourth outer sleeve 1402, the second mobile groove 1405 is provided with the second damping sleeve 16 for abutting with the second pressing rod 15, when the second pressing rod 15 moves upward in the second mobile groove 1405, the second pressing rod 15 is pressed in the second damping sleeve 16, avoiding the second pressing rod 15 rebounding, the connection mode of the second rotating assembly 14 with the first lower rubber plug 3 and the second lower rubber plug 4 and the connection mode of the first rotating assembly 9 with the first upper rubber plug 1 and the second upper rubber plug 2 are same, the upper rubber plug and the lower rubber plug can be bent by the same mode, and the sealing effect is maintained at the same time, the durability of the device is enhanced.

[0033] As shown in Figure 1 and Figure 13 As shown, as a preferred embodiment, on the basis of the above manner, further, the second pressing rod 15 is penetrated into the fourth outer sleeve 1402, the second mobile groove 1405 is provided with the second damping sleeve 16 for abutting with the second pressing rod 15, when the second pressing rod 15 moves upward in the second mobile groove 1405, the second pressing rod 15 is pressed in the second damping sleeve 16, avoiding the second pressing rod 15 rebounding, the connection mode of the second rotating assembly 14 with the first lower rubber plug 3 and the second lower rubber plug 4 and the connection mode of the first rotating assembly 9 with the first upper rubber plug 1 and the second upper rubber plug 2 are same, the upper rubber plug and the lower rubber plug can be bent by the same mode, and the sealing effect is maintained at the same time, the durability of the device is enhanced.

[0034] Embodiment 3: The schemes in the embodiments 1 and 2 are further introduced in combination with specific working modes, which are described in detail as follows: Specifically, the cementing rubber plug for the subsea oil well is used as follows: as shown in Figures 1-5 As shown, the first sealing ring 5, the second sealing ring 6, the third sealing ring 7 and the fourth sealing ring 8 can be pressed tightly with the inner wall of the casing after the first upper rubber plug 1 and the second upper rubber plug 2 abut with the first lower rubber plug 3 and the second lower rubber plug 4, so as to ensure the sealing effect, when the first upper rubber plug 1 and the second upper rubber plug 2 and the first lower rubber plug 3 and the second lower rubber plug 4 move downward to the bending section of the casing, the second outer sleeve 902 rotates in the first outer sleeve 901, the first convex plate 904 and the first sealing piston 903 can ensure the sealing effect of the first upper rubber plug 1 and the second upper rubber plug 2, the first outer sleeve 901 and the second outer sleeve 902 of the ball cover structure make the second upper rubber plug 2 keep sealing when rotating, because the connection mode of the second rotating assembly 14 with the first lower rubber plug 3 and the second lower rubber plug 4 and the connection mode of the first rotating assembly 9 with the first upper rubber plug 1 and the second upper rubber plug 2 are same, the lower rubber plug can be bent by the same mode as the upper rubber plug, the third outer sleeve 1401 and the fourth outer sleeve 1402 of the ball cover structure make the second lower rubber plug 4 not fall off when rotating on the first lower rubber plug 3, while keeping sealing, so as to adapt to the use of the sleeve bending section, the second sealing piston 1403 and the second convex plate 1404 ensure the sealing effect of the first lower rubber plug 3 and the second lower rubber plug 4.

[0035] As Figures 3-8 shown, the second lower rubber plug 4 moves to the bottom of the sleeve, the connecting plate 28 and the second pressure rod 15 are pressed, the second pressure rod 15 moves upward relative to the second lower rubber plug 4, the top of the second pressure rod 15 penetrates the inside of the fourth outer bushing 1402 and is in butt joint with the second damping sleeve 16, the resistance between the second damping sleeve 16 and the second pressure rod 15 makes the second spring 18 in the compressed state unable to rebound, thereby ensuring that the third outer bushing 1401 and the fourth outer bushing 1402 cannot rotate relative to each other, at the same time, the upward movement of the second pressure rod 15 increases the air pressure in the cavity 17 through the second opening 19, thereby making the fourth sealing ring 8 tightly support the inner wall of the sleeve, in this process, the annular groove 20 on the second pressure rod 15 makes the pressing block 21 no longer tightly support the sliding rod 23 and the scraping plate 29 through the third spring 22, the scraping plate 29 is automatically stored while automatically expanding the fourth sealing ring 8, thereby switching the scraping function to the sealing function. As Figure 1 shown, since the four scraping plates 29 on the device are arranged in a stepped manner and are all quarter circular rings, the device can stably store the scraping plate 29 while ensuring the scraping effect. As Figures 8-14 shown, when the second pressure rod 15 moves upward, the traction steel wire 1305 pulls one side of the support plate 1304 under the guidance of the guide wheel 1306, the first spring 1303 between the abutment plate 1301 and the guide rod 1302 is compressed, and the one side of the support plate 1304 rotates on the guide rod 1302 after being pulled, the tip of the notch 1308 abuts against the rupture disc 12, and the rupture disc 12 is ruptured. After the first upper rubber plug 1 and the second upper rubber plug 2 are in butt joint with the first lower rubber plug 3 and the second lower rubber plug 4, the first pressure rod 10 is pressed to slide in the second upper rubber plug 2, the first pressure rod 10 penetrates the inside of the second outer bushing 902 and is in butt joint with the first damping sleeve 11, and the first rotating assembly 9 is locked and cannot rotate.

[0036] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A cementing plug for subsea oil wells, comprising a first upper cementing plug (1), characterized in that, A first rotating assembly (9) is provided below the first upper plug (1), a second upper plug (2) is installed below the first rotating assembly (9), a first lower plug (3) is provided below the second upper plug (2), a second rotating assembly (14) is provided below the first lower plug (3), and a second lower plug (4) is installed below the second rotating assembly (14). A first sealing ring (5), a second sealing ring (6), a third sealing ring (7), and a fourth sealing ring (8) are respectively installed on the outer sides of the first upper plug (1), the second upper plug (2), the first lower plug (3), and the second lower plug (4). The fourth sealing ring (8) has an opening inside. The cavity (17) has a first pressure rod (10) installed inside the second upper rubber plug (2), a second pressure rod (15) and a rupture disc (12) installed inside the second lower rubber plug (4), a second spring (18) installed between the second pressure rod (15) and the second lower rubber plug (4), a second opening (19) opened inside the second lower rubber plug (4), a pressure block (21) and a slide rod (23) slidably installed on the second lower rubber plug (4), a third spring (22) installed between the pressure block (21) and the slide rod (23), a scraper (29) installed on the slide rod (23), and an annular groove (20) opened on the second pressure rod (15).

2. The cementing plug for subsea oil wells according to claim 1, characterized in that, A first leaf spring (24) and a first protective sleeve (25) are installed between the first lower rubber plug (3) and the second lower rubber plug (4), and a second leaf spring (26) and a second protective sleeve (27) are installed between the first upper rubber plug (1) and the second upper rubber plug (2).

3. The cementing plug for subsea oil wells according to claim 1, characterized in that, The first rotating assembly (9) includes a first outer bushing (901) fixedly connected to the bottom of the first upper rubber plug (1), a second outer bushing (902) fitted inside the first outer bushing (901), the second outer bushing (902) being fixedly connected to the second upper rubber plug (2), a first sealing piston (903) fixedly connected to the second outer bushing (902), and a first protrusion plate (904) fixedly provided inside the first upper rubber plug (1).

4. A cementing plug for subsea oil wells according to claim 3, characterized in that, The first outer bushing (901) has a first moving groove (905) inside, and a first damping sleeve (11) for docking with the first pressure rod (10) is installed in the first moving groove (905). The first pressure rod (10) passes through the interior of the second outer bushing (902) and the first sealing piston (903).

5. A cementing plug for subsea oil wells according to claim 1, characterized in that, The central axes of the rupture disc (12) and the second lower rubber plug (4) are collinear. The rupture disc (12) has a thickness distribution that gradually increases from the center to the edge. A traction assembly (13) is provided below the rupture disc (12).

6. A cementing plug for subsea oil wells according to claim 5, characterized in that, The traction assembly (13) includes a connecting plate (1301) and a guide wheel (1306) installed on the inner wall of the second lower rubber plug (4). A guide rod (1302) is slidably installed in the connecting plate (1301). A first spring (1303) is fixedly connected to the guide rod (1302). A support plate (1304) is installed on the guide rod (1302). A traction steel rope (1305) is fixedly connected to the support plate (1304). The traction steel rope (1305) is guided by the guide wheel (1306) and connected to one of the second pressure rods (15). A first opening (1307) is opened in the second lower rubber plug (4).

7. A cementing plug for subsea oil wells according to claim 6, characterized in that, The support plate (1304) is provided with a notch (1308), and the support plate (1304) and the guide rod (1302) are rotatably connected.

8. A cementing plug for subsea oil wells according to claim 1, characterized in that, The second rotating assembly (14) includes a third outer bushing (1401) fixedly connected to the bottom of the first lower rubber plug (3), a fourth outer bushing (1402) attached to the inner wall of the third outer bushing (1401), the bottom of the fourth outer bushing (1402) connected to the second lower rubber plug (4), a second sealing piston (1403) fixedly connected to the fourth outer bushing (1402), a second protrusion (1404) fixedly provided inside the first lower rubber plug (3), and a second moving groove (1405) opened inside the third outer bushing (1401).

9. A cementing plug for subsea oil wells according to claim 8, characterized in that, The second pressure rod (15) passes through the fourth outer bushing (1402). The second moving groove (1405) is equipped with a second damping sleeve (16) for docking with the second pressure rod (15). The connection method between the second rotating assembly (14) and the first lower rubber plug (3) and the second lower rubber plug (4) and the connection method between the first rotating assembly (9) and the first upper rubber plug (1) and the second upper rubber plug (2) are the same.

10. A cementing plug for subsea oil wells according to claim 1, characterized in that, The second pressure rod (15) is evenly distributed along the circumference of the second lower rubber plug (4), and a connecting plate (28) is fixedly connected between two adjacent second pressure rods (15).

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