High-temperature-resistant and corrosion-resistant rubber plug

Abstract

The invention relates to the technical field of well cementation rubber plugs, in particular to a high-temperature-resistant and corrosion-resistant rubber plug which comprises a lower rubber plug body and an upper rubber plug body, the top end of the lower rubber plug body is provided with a funnel-shaped circular truncated cone guiding part which is gradually expanded upwards in the axial direction, and the outer portion of the lower rubber plug body is provided with three annular mud scraping wings used for scraping drilling fluid on the inner wall of a shaft. An expansion locking assembly is arranged between every two annular mud scraping wings, the expansion locking assemblies are arranged, the embedded notches form radial limiting and directional guiding on the inner pressing ring bags, controllable radial expansion is generated between the adjacent annular mud scraping wings through the expansion filling rings, and attaching gaps possibly generated due to abrasion of the mud scraping wings are effectively compensated; the lower rubber plug body is tightly attached to the inner wall of the shaft, the friction locking force between the lower rubber plug body and the inner wall of the shaft is remarkably improved, the problem that anchoring of a traditional rubber plug is insufficient due to abrasion of a mud scraping wing is solved, and the axial fixing effect and the annular sealing performance of the lower rubber plug body in the shaft are enhanced.

Description

Technical Field

[0001] This invention relates to the technical field of cementing plugs, and in particular to high-temperature and corrosion-resistant cementing plugs. Background Technology

[0002] In low-carbon mining operations, particularly during cementing operations, rubber plugs are crucial tools for ensuring cement slurry displacement efficiency and wellbore sealing integrity. Conventional rubber plugs typically employ an integrated rubber structure, relying on the interference fit between their outer annular scraper blades and the inner wall of the wellbore to remove drilling fluid mud cake and isolate cement slurry. However, with increasing wellbore depth and more complex downhole conditions, existing rubber plug structures have revealed significant shortcomings in practical applications. Under prolonged descent and high-pressure fluid scouring, the scraper blades on the outer periphery of the rubber plug are prone to wear, leading to a decrease in the fit with the inner wall of the wellbore and a weakening of the frictional locking force. Consequently, when the rubber plug is seated and fixed at the bottom of the wellbore at the float ring, the fit with the inner wall of the wellbore is insufficient, making it difficult to form a reliable anchor and thus weakening the axial fixing effect of the rubber plug. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a high-temperature and corrosion-resistant rubber stopper.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a high-temperature and corrosion-resistant rubber stopper, comprising a lower rubber stopper body and an upper rubber stopper body, both of which are integrally molded components, and both are made of conventional high-temperature and corrosion-resistant rubber materials. The top part of the lower rubber stopper body is provided with a funnel-shaped frustum guide portion that gradually expands upward in the axial direction. The upper end of the funnel-shaped frustum guide portion is provided with a downwardly tapering upper groove. The interior of the lower rubber stopper body is provided with a central flow hole. The bottom end of the central flow hole is provided with a rubber diaphragm for isolating cement slurry. The lower end of the lower rubber stopper body is provided with a conical guide portion for guiding. The exterior of the conical guide portion is provided with several locking portions, which are arranged in a ring and equally spaced outside the conical guide portion. The exterior of the lower rubber stopper body is provided with three annular mud scraper wings for scraping drilling fluid from the inner wall of the wellbore. The funnel-shaped frustum guide portion, the annular mud scraper wings, and the conical guide portion are integrally molded and fitted together from top to bottom along the axial direction of the lower rubber stopper body. An expansion locking assembly is provided between each pair of annular scraper blades to assist in fixing the lower and upper rubber plug bodies. Each expansion locking assembly includes an inner groove, which is located on the outside of the lower rubber plug body. The inside of the inner groove is a gradually expanding trapezoidal annular hole. An inner pressure ring is movably connected inside the inner groove. One end of the inner pressure ring extends away from the inside of the inner groove to the space between the two annular scraper blades. An expansion filling ring is provided on the outside of the inner pressure ring for pressing against the inner wall of the wellbore. The expansion filling ring is located between the two annular scraper blades. The inner pressure ring and the expansion filling ring are integrally formed.

[0005] As a preferred embodiment of the present invention, the upper plug body comprises an upper drill bit guide section and a lower embedded insertion section. The upper end of the upper drill bit guide section is provided with a guide head and a tapered groove for guiding the drill bit. The tapered groove is opened at the upper end of the guide head. The lower end of the lower embedded insertion section is provided with an insertion end for guiding it into the central flow hole. The lower end of the insertion end is provided with a return stop. The diameter of the return stop is larger than the diameter of the lower end of the insertion end, and the return stop is tapered downwards. A plurality of locking teeth are provided on the side of the return stop near the insertion end. The plurality of locking teeth are arranged in a ring-shaped equal distribution outside the return stop.

[0006] As a preferred technical solution of the present invention, the outer periphery of the guide head is provided with a plurality of vertical through slots for relieving pressure, and the plurality of vertical through slots are arranged in an equally spaced ring around the outer periphery of the guide head.

[0007] As a preferred embodiment of the present invention, the lower embedded insertion section is provided with a downwardly tapering connecting and pressing section on the side near the upper drill bit guide section.

[0008] As a preferred technical solution of the present invention, a pressure-locking assembly for further fixing the upper plug body to the inner wall of the wellbore is provided between the guide head and the connecting flat pressure part. The pressure-locking assembly includes a pressure-stabilizing upper ring, a fixing ring, a buffer convex ring and two snap-fit ​​rings. The fixing ring is located outside the upper drill bit guide section. The two snap-fit ​​rings are respectively located on the upper and lower sides outside the buffer convex ring, and the two snap-fit ​​rings are respectively connected to the pressure-stabilizing upper ring and the fixing ring. The pressure-stabilizing upper ring is movably sleeved outside the upper drill bit guide section through the fixing ring and the two snap-fit ​​rings. A slot is opened on the side of the pressure-stabilizing upper ring that is close to the fixing ring. A radial expansion ring is provided on the side of the pressure-stabilizing upper ring that is close to the fixing ring. A receiving slot is opened on the side of the fixing ring that is close to the pressure-stabilizing upper ring.

[0009] Compared with the prior art, the beneficial effects that this invention can achieve are: 1. This invention, by setting an expansion locking component, wherein the embedded groove forms a radial limit and directional guide for the inner pressure ring bladder, when the upper rubber plug body descends and squeezes the central flow hole, the inner pressure ring bladder is compressed and transmits the medium to the expansion filling ring, so that the expansion filling ring generates controllable radial expansion between adjacent annular scraper blades, effectively compensating for the fitting gap that may be caused by the wear of the scraper blades, and forming a tight fit with the inner wall of the wellbore, significantly improving the frictional locking force between the lower rubber plug body and the inner wall of the wellbore, thereby overcoming the problem of insufficient anchoring caused by the wear of the scraper blades in traditional rubber plugs, and strengthening the axial fixing effect and annular sealing performance of the lower rubber plug body in the wellbore.

[0010] 2. This invention, through the insertion end axially penetrating the lower rubber plug body along the central flow hole, and in conjunction with the rigid contact and limiting of the lower end face of the backstop and the conical guide, effectively prevents the upper rubber plug body from axially rebounding and dislodging under the fluctuation of downhole annular back pressure and displacement fluid pressure, thus achieving reliable axial anti-dislodgement locking between the upper and lower rubber plug bodies, significantly improving the axial stability and operational safety after the rubber plug is set.

[0011] 3. The present invention forms a reliable anti-rotation constraint by using a circumferential limiting structure in conjunction with the circumferential meshing of the locking teeth and the locking part. Even when only partially engaged, it can still effectively increase the rotational friction resistance of the upper rubber plug body, preventing it from rotating synchronously with the drill bit during drilling operations, thereby ensuring the smoothness and safety of drilling operations.

[0012] 4. The present invention sets up a pressure-locking component and its radial expansion ring to enter the groove under axial pressure. After being pressed, it generates radial outward expansion deformation, driving the outer peripheral surface of the fixed ring to form a tight fit with the inner wall of the well barrel, which greatly improves the static friction resistance between the fixed ring and the inner wall of the well barrel, thereby significantly enhancing the axial and circumferential stability of the upper rubber plug body in the well barrel. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the lower rubber stopper body of the present invention; Figure 2 This is a partial cross-sectional view of the lower rubber stopper body of the present invention; Figure 3 This is a schematic diagram of the embedded slot structure of the present invention; Figure 4 This is a schematic diagram of the structure of the rubber stopper body of the present invention; Figure 5 This is a schematic diagram of the insertion structure between the lower rubber stopper body and the upper rubber stopper body of the present invention; Figure 6 This is a schematic diagram of the structure of the expansion filling ring of the present invention; Figure 7 This is a schematic diagram of the voltage regulator upper ring of the present invention.

[0014] The components are as follows: 10. Lower rubber plug body; 11. Annular scraper blade; 12. Funnel-shaped frustum guide section; 13. Upper groove opening; 14. Conical guide section; 15. Locking section; 16. Central flow hole; 20. Upper rubber plug body; 21. Upper drill bit guide section; 22. Lower embedded insertion section; 23. Insertion end; 24. Return stop section; 25. Locking tooth; 26. Guide head; 27. Conical groove opening; 28. Vertical through groove opening; 29. ​​Connecting flat pressure section; 30. Embedded groove opening; 31. Inner pressure ring bladder; 32. Expansion filling ring; 40. Pressure stabilizing upper ring; 41. Fixing ring section; 42. Radial expansion ring; 43. Connecting groove opening; 44. Buffer protrusion ring; 45. Locking ring section; 46. Empty groove opening. Detailed Implementation

[0015] To make the technical means, creative features, and achieved objectives and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments described herein without creative effort are all within the protection scope of this invention. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0016] Example: Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, the high-temperature and corrosion-resistant rubber plug includes a lower rubber plug body 10 and an upper rubber plug body 20. Both the lower rubber plug body 10 and the upper rubber plug body 20 are integrally molded components, and both are made of high-temperature and corrosion-resistant rubber material. The material is hydrogenated nitrile butadiene rubber (HNBR), suitable for medium and deep wells and most industrial cementing. It is suitable for long-term continuous operation with a temperature resistance of -40℃ to 160℃, and a short-term instantaneous temperature resistance of up to 180℃. It is resistant to corrosion by strong alkaline hydrated cement slurry, resisting the penetration of strong alkaline ions in cement hydration, and avoiding rubber swelling, softening and failure. The top part of the lower rubber plug body 10 is provided with a funnel-shaped frustum guide part 12 that gradually expands upward in the axial direction. The upper end of the funnel-shaped frustum guide part 12 is opened The lower plug body 10 has a downwardly tapering upper groove 13. A central flow hole 16 is provided inside the lower plug body 10. A rubber diaphragm is provided at the bottom of the central flow hole 16 to isolate the cement slurry. A conical guide part 14 is provided at the lower end of the lower plug body 10 for guiding. Several locking parts 15 are provided on the outside of the conical guide part 14. The conical guide part 14 is connected to the inside of the central flow hole 16. Several locking parts 15 are arranged in a ring and equally distributed on the outside of the conical guide part 14. Three annular mud scraper wings 11 are provided on the outside of the lower plug body 10 for scraping the drilling fluid from the inner wall of the well. The funnel-shaped frustum guide part 12, the annular mud scraper wings 11 and the conical guide part 14 are integrally formed and fitted from top to bottom along the axial direction of the lower plug body 10.

[0017] During cementing operations, the lower plug body 10 is first inserted into the wellbore cavity. The axial hydraulic driving force generated by the injected cement slurry in the wellbore acts on the upper end face of the lower plug body 10, pushing it downward along the wellbore axis. As the lower plug body 10 descends, its outer circumference forms multiple annular mud scraper blades 11 that fit tightly against the inner wall of the wellbore, continuously scraping away drilling fluid mud cake and residual solid impurities adhering to the inner wall of the wellbore, providing a clean interface for the subsequent connection between the upper plug body 20 and the inner wall of the wellbore. When the lower plug body 10 descends to the float position at the bottom of the wellbore... When the lower rubber plug body 10 is in place, the tapered guide part 14 at the lower end of the lower rubber plug body 10 cooperates with the corresponding positioning structure of the float hoop for guidance. The axial limiting structure of the float hoop forms a stable axial stop for the lower rubber plug body 10, realizing the lower rubber plug body 10's seat positioning. At this time, cement slurry is continuously pumped into the wellbore, and the hydraulic pressure in the wellbore continues to rise. When the pressure reaches the preset rupture pressure of the rubber diaphragm at the bottom of the central flow hole 16, the rubber diaphragm ruptures to open the central flow hole 16. The cement slurry continues to flow down through the central flow hole 16 of the lower rubber plug body 10 and enters the annulus between the wellbore and the formation to complete the subsequent cement injection operation.

[0018] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 An expansion locking assembly is provided between each pair of annular scraper blades 11 to assist in fixing the lower rubber plug body 10 and the upper rubber plug body 20. Each expansion locking assembly includes an embedded groove 30, which is opened on the outside of the lower rubber plug body 10. The inside of the embedded groove 30 is a gradually expanding trapezoidal annular hole. An inner pressure ring bladder 31 is movably connected inside the embedded groove 30. One end of the inner pressure ring bladder 31 away from the inside of the embedded groove 30 extends to the space between the two annular scraper blades 11. An expansion filling ring 32 is provided on the outside of the inner pressure ring bladder 31 to abut against the inner wall of the wellbore. The interiors of the inner pressure ring bladder 31 and the expansion filling ring 32 are hollow and connected. The expansion filling ring 32 is located between the two annular scraper blades 11. The inner pressure ring bladder 31 and the expansion filling ring 32 are integrally formed hollow sealing structures filled with high-temperature resistant hydraulic medium.

[0019] The upper plug body 20 comprises an upper drill bit guide section 21 and a lower embedded insertion section 22. The upper end of the upper drill bit guide section 21 is provided with a guide head 26 for guiding the drill bit and a tapered groove 27. The tapered groove 27 is opened at the upper end of the guide head 26. The lower end of the lower embedded insertion section 22 is provided with an insertion end 23 for guiding its insertion into the central flow hole 16. The lower end of the insertion end 23 is provided with a return stop 24. The diameter of the return stop 24 is larger than the diameter of the lower end of the insertion end 23, and the return stop 24 is tapered downwards. As the upper plug body 20 continues to descend axially, the insertion end 23 at the bottom of the lower embedded insertion section 22 is inserted into the center of the lower plug body 10 first. Inside the flow hole 16; under the axial hydraulic driving force of the upper rubber plug body 20, the insertion end 23 axially penetrates the lower rubber plug body 10 and the tapered guide portion 14 at the bottom end along the central flow hole 16, and finally extends to the lower end of the lower rubber plug body 10. When the downhole annular back pressure and displacement fluid pressure fluctuations form an axial rebound force on the upper rubber plug body 20, because the maximum outer diameter of the return stop portion 24 is greater than the outer diameter of the insertion end 23 and the inner diameter of the central flow hole 16, the upper end face of the return stop portion 24 and the lower end face of the tapered guide portion 14 form a tight rigid abutment limit, preventing the upper rubber plug body 20 from axially rebounding and coming out, thus realizing the axial anti-disengagement locking of the upper rubber plug body 20 and the lower rubber plug body 10.

[0020] A plurality of locking teeth 25 are provided on the outer side of the return stop 24 near the insertion end 23. These locking teeth 25 are arranged in a ring-shaped, evenly spaced pattern on the outer side of the return stop 24. The ring-shaped, evenly distributed locking teeth 25 on the outer periphery of the return stop 24 engage with a plurality of locking portions 15 on the outer periphery of the tapered guide 14, forming a stable circumferential limiting structure. During subsequent drilling operations, when the drill bit penetrates the upper rubber plug body 20, this circumferential limiting structure provides a reliable circumferential anti-rotation constraint on the upper rubber plug body 20. Furthermore, the locking teeth 25 and locking portions 15 do not need to be locked one-to-one; even partial engagement can form a circumferential anti-rotation constraint, preventing the upper rubber plug body 20 from rotating synchronously with the drill bit, effectively preventing the upper rubber plug body 20 from rotating. The rubber plug body 20 rotates synchronously with the drill bit to ensure smooth drilling operations. The lower embedded insertion section 22 has a downwardly tapering connecting flat pressure part 29 on the side near the upper drill bit guide section 21. After the upper rubber plug body 20 and the lower rubber plug body 10 are embedded and connected, the lower end of the connecting flat pressure part 29 is pressed against the upper end of the funnel-shaped frustum guide part 12. The connecting flat pressure part 29 and the funnel-shaped frustum guide part 12 press against each other, forming a seal in the middle of the mating part between the upper rubber plug body 20 and the lower rubber plug body 10. The conical groove 27, the connecting flat pressure part 29, the upper drill bit guide section 21, the lower embedded insertion section 22, the insertion end 23 and the return stop part 24 are integrally formed.

[0021] After the lower rubber plug body 10 descends to the float ring position at the bottom of the wellbore and is fixed in place, the upper rubber plug body 20 is inserted into the wellbore cavity. The axial hydraulic driving force generated by the pumped displacement fluid pushes the upper rubber plug body 20 downwards along the wellbore axis until the upper rubber plug body 20 and the lower rubber plug body 10 are properly seated. During this engagement, the insertion end 23 at the bottom of the lower embedded insertion section 22 first contacts the funnel-shaped frustum guide portion 12 at the top of the lower rubber plug body 10. Guided and centered by the upper groove opening 13, it smoothly embeds into the central flow hole 16. As the upper rubber plug body 20 continues to descend, the lower embedded insertion section 22 forms a radial extrusion force on the inner wall of the central flow hole 16. The pressure causes the central flow hole 16 to expand radially outward. As the central flow hole 16 expands, it compresses the inner pressure ring 31 within the embedded groove 30. After being compressed, the medium inside the inner pressure ring 31 flows into the expansion filling ring 32 connected to it, driving the expansion filling ring 32 to expand radially outward between the two adjacent annular scraper blades 11. The expanded expansion filling ring 32 fills the annular space gap between the adjacent annular scraper blades 11 and forms a tight fit with the inner wall of the well, greatly improving the frictional locking force between the lower rubber plug body 10 and the inner wall of the well, and further strengthening the axial fixation effect and annular sealing performance of the lower rubber plug body 10 in the well.

[0022] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 7 A pressure-locking assembly is provided between the guide head 26 and the connecting flat pressure part 29 to further fix the upper rubber plug body 20 to the inner wall of the wellbore. The pressure-locking assembly includes a pressure-stabilizing upper ring 40, a fixing ring 41, a buffer convex ring 44, and two snap-fit ​​rings 45. The fixing ring 41 is located outside the upper drill bit guide section 21. The two snap-fit ​​rings 45 are respectively located on the upper and lower sides outside the buffer convex ring 44, and the two snap-fit ​​rings 45 are respectively connected to the pressure-stabilizing upper ring 40 and the fixing ring 41. The pressure-stabilizing upper ring 40 is movably sleeved on the upper drill bit guide section 21 through the fixing ring 41 and the two snap-fit ​​rings 45. On the outside, the pressure stabilizing upper ring 40 is provided with a slot 46 on the side close to the fixed ring 41. After the pressure stabilizing upper ring 40 is subjected to pressure and moves downward outside the upper drill bit guide section 21, the pressure stabilizing upper ring 40 drives the locking ring 45 and causes the buffer convex ring 44 to be laterally compressed and expanded inside the two slots 46. The expansion of the buffer convex ring 44 inside the two slots 46 tightly locks the pressure stabilizing upper ring 40 and the fixed ring 41. The pressure stabilizing upper ring 40 is provided with a radial expansion ring 42 on the side close to the fixed ring 41, and the fixed ring 41 is provided with a slot 43 on the side close to the pressure stabilizing upper ring 40.

[0023] The outer periphery of the guide head 26 is provided with several vertical through-holes 28 for pressure relief. The several vertical through-holes 28 are arranged in an equally spaced ring around the outer periphery of the guide head 26. The vertical through-holes 28 are used to divert and distribute the pressure transmitted by the displacement fluid to the upper end of the rubber plug, so that the pressure is evenly transmitted to the upper end face of the pressure stabilizing ring 40. This ensures that the pressure stabilizing ring 40 can respond to axial pressure changes in a timely and stable manner, thereby driving the pressure locking assembly to operate reliably and enhancing the locking and sealing effect of the rubber plug in the wellbore.

[0024] When the pressure-stabilizing upper ring 40 moves downward along the axial direction of the upper drill bit guide section 21 under axial pressure, it drives the radial expansion ring 42 at its lower end to move downward synchronously, so that the radial expansion ring 42 enters the groove 43 at the upper end of the fixed ring part 41 and is axially pressed; after being pressed, the radial expansion ring 42 generates radial outward expansion deformation, forming a radial support force on the inner wall of the groove 43, driving the outer circumference of the fixed ring part 41 to expand outward and form a tight fit with the inner wall of the wellbore, greatly increasing the static friction resistance between the fixed ring part 41 and the inner wall of the wellbore, thereby further enhancing the axial and circumferential stability of the upper rubber plug body 20 in the wellbore. The fixed ring part 41 and the upper drill bit guide section 21 are integrally formed, and the pressure-stabilizing upper ring 40, the buffer convex ring 44, and the two snap-fit ​​ring parts 45 are all integrally formed.

[0025] Working principle: In use: First, the lower rubber plug body 10 is inserted into the wellbore cavity. The axial hydraulic driving force formed by the cement slurry pushes the lower rubber plug body 10 downward. The multi-ringed mud scraper 11 integrally formed on its outer circumference fits tightly against the inner wall of the wellbore, continuously scraping away the drilling fluid mud cake and residual solid impurities attached to the inner wall of the wellbore. When the lower rubber plug body 10 descends to the position of the float hoop at the bottom of the wellbore, the tapered guide part 14 at its lower end cooperates with the corresponding positioning structure of the float hoop to guide it. The axial limiting structure of the float hoop forms a stable axial stop for the lower rubber plug body 10, completing the seating and positioning. Continue pumping cement slurry until the pressure reaches the preset value. The rubber diaphragm at the bottom of the central flow hole 16 breaks to open the central flow hole 16. The cement slurry descends through the central flow hole 16 into the annulus between the wellbore and the formation, completing the cement injection operation.

[0026] The second step involves inserting the upper rubber plug body 20 into the wellbore cavity. The axial hydraulic driving force generated by the displacement fluid pushes the upper rubber plug body 20 downward along the wellbore axis. The insertion end 23 at the bottom of the lower embedded insertion section 22 first contacts the funnel-shaped frustum guide part 12 at the top of the lower rubber plug body 10. It is then smoothly inserted into the center flow hole 16 by the guiding and centering effect of the upper groove 13. When the insertion end 23 passes through the lower rubber plug body 10 and the tapered guide part 14 at the bottom along the center flow hole 16 and extends to the outside of its lower end, the upper end face of the return stop part 24 and the lower end face of the tapered guide part 14 form a tight rigid abutment limit, preventing the upper rubber plug body 20 from axially rebounding and falling out. At the same time, a number of locking teeth 25 evenly distributed in a ring around the outer periphery of the return stop part 24 and a number of locking parts 15 provided on the outer periphery of the tapered guide part 14 form a circumferential meshing and locking, forming a stable circumferential anti-rotation structure.

[0027] In the third step, during the downward insertion of the upper rubber plug body 20, the lower embedded insertion section 22 forms radial compression on the inner wall of the central flow hole 16, causing the central flow hole 16 to expand radially outward. Simultaneously, it compresses the inner pressure ring 31 in the embedded groove 30. After the inner pressure ring 31 is compressed, the medium filled inside it flows into the expansion filling ring 32 connected to it, driving the expansion filling ring 32 to expand radially outward between the two adjacent annular mud scraper wings 11, tightly fitting the inner wall of the wellbore, thereby improving the frictional locking force between the lower rubber plug body 10 and the inner wall of the wellbore, and strengthening the axial fixing effect and annular sealing performance.

[0028] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A high-temperature and corrosion-resistant rubber stopper, comprising a lower rubber stopper body (10) and an upper rubber stopper body (20), wherein the lower rubber stopper body (10) and the upper rubber stopper body (20) are both integrally formed components, characterized in that, The top part of the lower rubber plug body (10) is provided with a funnel-shaped frustum guide part (12) that expands axially upward. The upper end of the funnel-shaped frustum guide part (12) is provided with a downward-shrinking upper groove opening (13). The interior of the lower rubber plug body (10) is provided with a central flow hole (16). The bottom end of the interior of the central flow hole (16) is provided with a rubber diaphragm to isolate the cement slurry. The lower end of the lower rubber plug body (10) is provided with a conical guide part (14) for guiding. The exterior of the lower rubber plug body (10) is provided with three annular mud scraper wings (11) for scraping the drilling fluid from the inner wall of the well. The funnel-shaped frustum guide (12), the annular scraper (11) and the conical guide (14) are integrally formed from top to bottom along the axial direction of the lower rubber plug body (10); An expansion locking assembly is provided between each pair of annular scraper blades (11) to assist in fixing the lower rubber plug body (10) and the upper rubber plug body (20); Each expansion locking assembly includes an embedded slot (30) which is opened on the outside of the lower rubber plug body (10). An inner pressure ring bladder (31) is movably connected inside the embedded slot (30). An expansion filling ring (32) for abutting against the inner wall of the wellbore is provided on the outside of the inner pressure ring bladder (31). The upper plug body (20) consists of an upper drill bit guide section (21) and a lower embedded insertion section (22).

2. The high-temperature and corrosion-resistant rubber stopper according to claim 1, characterized in that, The tapered guide portion (14) has several locking portions (15) on its outside, and the several locking portions (15) are arranged in a ring and equally distributed on the outside of the tapered guide portion (14).

3. The high-temperature and corrosion-resistant rubber stopper according to claim 1, characterized in that, The upper end of the upper drill bit guide section (21) is provided with a guide head (26) and a tapered groove (27) for guiding the drill bit. The tapered groove (27) is opened at the upper end of the guide head (26). The lower end of the lower embedded insertion section (22) is provided with an insertion end (23) for guiding it to be embedded into the center flow hole (16). The lower end of the plug end (23) is provided with a stop part (24). The outer diameter of the stop part (24) is larger than the outer diameter of the plug end (23) and the inner diameter of the central flow hole (16), and the stop part (24) is a downward tapering shape.

4. The high-temperature and corrosion-resistant rubber stopper according to claim 3, characterized in that, The outer side of the stop portion (24) near the insertion end (23) is provided with a number of locking teeth (25), and the number of locking teeth (25) are arranged in a ring-shaped even distribution outside the stop portion (24).

5. The high-temperature and corrosion-resistant rubber stopper according to claim 3, characterized in that, The outer periphery of the guide head (26) is provided with a number of vertical through slots (28) for pressure relief, and the number of vertical through slots (28) are arranged in an equally spaced ring around the outer periphery of the guide head (26).

6. The high-temperature and corrosion-resistant rubber stopper according to claim 3, characterized in that, The lower embedded insertion section (22) has a downwardly tapering connecting flat pressure part (29) on the side near the upper drill bit guide section (21), after the upper rubber plug body (20) and the lower rubber plug body (10) are embedded and connected.

7. The high-temperature and corrosion-resistant rubber stopper according to claim 6, characterized in that, A pressure-locking assembly is provided between the guide head (26) and the connecting flat pressure part (29) to assist in further fixing the upper rubber plug body (20) to the inner wall of the well barrel; The pressure-locking assembly includes a pressure-stabilizing upper ring (40), a fixed ring (41), a buffer convex ring (44), and two snap-fit ​​rings (45). The fixed ring (41) is located outside the upper drill bit guide section (21), and the two snap-fit ​​rings (45) are respectively located on the upper and lower sides outside the buffer convex ring (44), and the two snap-fit ​​rings (45) are respectively connected to the pressure-stabilizing upper ring (40) and the fixed ring (41).

8. The high-temperature and corrosion-resistant rubber stopper according to claim 7, characterized in that, The pressure stabilizing upper ring (40) has an empty slot (46) on the side close to the fixed ring (41). After the pressure stabilizing upper ring (40) is subjected to pressure and moves downward outside the upper drill bit guide section (21), the pressure stabilizing upper ring (40) drives the snap ring (45) and causes the buffer convex ring (44) to be laterally compressed and expanded inside the two empty slots (46). The expansion of the buffer convex ring (44) inside the two empty slots (46) tightly locks the pressure stabilizing upper ring (40) and the fixed ring (41). The upper voltage stabilizing ring (40) has a radial expansion ring (42) on the side near the fixed ring (41), and the fixed ring (41) has a groove (43) on the side near the upper voltage stabilizing ring (40).

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