Blowout preventer and rubber core sealing adjusting method

Abstract

The invention provides a blowout preventer and a rubber core sealing adjusting method, and belongs to the technical field of drilling equipment. The blowout preventer comprises an upper shell and a lower shell connected with the upper shell, the self-aligning blowout preventer further comprises a self-aligning assembly, and the self-aligning assembly is installed between the upper shell and the lower shell and is positioned and fixed through the upper shell and the lower shell; the self-aligning assembly comprises a first shell, a rubber core, an upper aligning unit and a lower aligning unit, the first shell is fixedly arranged between the upper shell and the lower shell, the rubber core is arranged in the first shell and makes contact with the upper aligning unit and the lower aligning unit which are installed in the first shell, and the upper aligning unit is used for adjusting the position between the upper portion of the rubber core and the drill rod. The technical problem that in the prior art, in the dynamic well drilling process of a drill column, due to heterogeneity of stratum lithology, the drill column generates high-frequency vibration, so that sealing deviation of a rubber core of the rotary blowout preventer and a drill rod causes sealing failure can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of drilling equipment, in particular to a blowout preventer and a rubber core seal adjustment method. Background Art

[0002] In oil and gas drilling projects, the well control system is the core line of defense for operational safety. As a key component of this system, the rotary blowout preventer (BOP) plays an irreplaceable role in underbalanced drilling and managed pressure drilling (MPD) technologies. Its core function is to achieve an effective dynamic seal within the rotating drill string annulus or, in emergency situations, completely seal the wellhead through the controlled radial deformation of a high-performance elastomeric core. This mechanism ensures that under critical operating conditions, the wellbore hydrostatic column pressure is precisely controlled to a level slightly below the formation pore pressure, enabling safe, pressurized drilling and effectively preventing catastrophic events such as kicks and blowouts.

[0003] During dynamic drilling, the drill string generates high-frequency vibrations as it rotates and moves up and down due to formation lithologic heterogeneity—that is, variations in rock hardness and properties at different locations in the formation. This high-frequency vibration causes the center of the seal between the drill string and the rotary BOP rubber core to shift, significantly impacting the sealing effect. Furthermore, the eccentric contact between the rubber core's sealing surface and the drill pipe subjects the rubber core to long-term high-intensity, non-uniform loads, reducing its fatigue life.

[0004] American Petroleum Institute (API) failure statistics show that 60% of rubber core failures are directly attributed to eccentric wear, significantly shortening their actual lifespan by 30-50% compared to their theoretical value. This problem not only leads to high spare parts costs for companies, but frequent rubber core replacements also cause unplanned drilling downtime, seriously affecting the continuity of drilling operations and significantly increasing drilling costs.

[0005] Patent publication number CN118958912A discloses an annular rubber core and a blowout preventer (BOP). The invention relates to the field of oil drilling and production technology. The annular rubber core comprises a rubber ring and a steel ring attached to its bottom surface, which are bonded together by vulcanization, with the bonding surfaces of the two being of uniform size. The BOP comprises a main body comprising a top cover, an outer shell, and multiple pistons disposed within the main body. A through slot extending vertically through the center of the main body is provided for inserting a drill pipe, and the top cover covers the outer shell. A first wear-resistant plate is disposed at the bottom of the top cover. Multiple rubber cores of equal thickness but varying outer diameters are arranged sequentially from the inside out. The outermost annular rubber core abuts the inner wall of the outer shell, while the rubber ring on the top surface of the annular rubber core abuts the first wear-resistant plate. Multiple pistons are connected to the corresponding steel rings of the annular rubber core and are used to move the steel ring upwards to ensure that the innermost rubber ring abuts the drill pipe. If one annular rubber core becomes worn and its sealing performance is compromised, all the annular rubber cores do not need to be replaced.

[0006] The invention patent with announcement number: CN113250640B discloses an annular blowout preventer, wherein a rotating sleeve is movably installed at the bottom of the shell, a rubber core is movably installed at the top of the support tube inside the shell, a piston is movably installed at the outer ring of the support tube and the bottom of the rubber core inside the shell, an oil pressure regulating groove is opened in the middle of the inner wall of the shell, an oil pumping plug is movably sleeved at the bottom of the oil pressure regulating groove, a hydraulic ring groove is opened at the bottom position of the inner wall of the shell, a rubber plug is movably sleeved at the inner ring of the hydraulic ring groove, a guide wheel is movably sleeved inside the contraction groove, cams are fixedly installed on both sides of the guide wheel, hydraulic regulating chambers are opened at the bottom position of the hydraulic regulating groove on both sides of the inner wall of the shell, a push rod is movably sleeved inside the hydraulic regulating chamber, and hydraulic chambers are symmetrically opened on the front and back sides of the inner wall of the shell. Through the cooperation of the shell structure, the internal guide wheel and the rubber plug, the damage to the rubber core in the blowout preventer is guaranteed to be small, and the working efficiency when pulling out the drill pipe is improved.

[0007] The invention patent with the announcement number CN114635663B discloses a closed-loop control method for a rotary blowout preventer. The method is implemented using a rotary blowout preventer and a hydraulic control device. The rotary blowout preventer includes a housing assembly, a rotary assembly, and a drilling fluid recovery and drainage device. The housing assembly includes a housing, a first pressure sensor, and at least two sets of hydraulic cylinder locking assemblies. The housing is fixedly and sealedly connected to the wellhead annular blowout preventer. The first pressure sensor can detect the internal pressure of the housing. The at least two sets of hydraulic cylinder locking assemblies lock the rotary assembly to the housing assembly. The drilling fluid recovery and drainage device can pump leaked drilling fluid into a drilling fluid circulation tank. The rotary assembly is disposed in the housing assembly and can rotate relative to the housing assembly along its axis. The rotary assembly can also seal the internal channel of the housing assembly. The hydraulic control device is connected to the rotary blowout preventer to control the rotary blowout preventer.

[0008] During drilling operations, formation lithologic heterogeneity induces intense multimodal vibrations in the drill string, resulting in dynamic center deviation as it passes through the rotary blowout preventer (BOP). This results in localized, high-stress, eccentric contact between the drill string's outer wall and the rubber core sealing surface. This off-design contact pattern significantly accelerates eccentric wear and failure of the rubber core, significantly shortening its service life and weakening the rotary BOP's critical sealing barrier function during underbalanced drilling, significantly increasing well control risks. Summary of the Invention

[0009] The purpose of the present invention is to provide a blowout preventer and rubber core seal adjustment method, which can effectively solve the technical problem in the prior art that during dynamic drilling, the drill string generates high-frequency vibration due to the heterogeneity of the formation lithology, which causes the rotary blowout preventer rubber core and drill pipe seal to deviate, resulting in seal failure.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is: A blowout preventer includes an upper shell and a lower shell connected to the upper shell. The present invention also includes a self-aligning assembly, which is installed between the upper shell and the lower shell and is positioned and fixed by the upper shell and the lower shell; Among them, the self-aligning assembly includes a first shell, a rubber core, an upper centering unit and a lower centering unit. The first shell is fixedly arranged between the upper shell and the lower shell. The rubber core is arranged in the first shell, and the rubber core is in contact with the upper centering unit and the lower centering unit installed in the first shell; the upper centering unit is used to adjust the position between the upper part of the rubber core and the drill rod, and the lower centering unit is used to adjust the position between the lower part of the rubber core and the drill rod.

[0011] The upper centering unit includes a displacement sensor and several centering hydraulic cylinders. The several centering hydraulic cylinders are arranged in the first shell at equal intervals, and the movable ends of the centering hydraulic cylinders are in contact with the side surfaces of the rubber core; the displacement sensor is installed on the inner wall of the first shell.

[0012] The lower centering unit includes a centering frame, a centering ring, a centering ball cage and a centering bead. The inner wall of the centering frame is provided with a first circular arc track, and the outer wall of the centering ring is provided with a second circular arc track. The second circular arc track cooperates with the first circular arc track on the inner wall of the centering frame. The centering bead is installed on the centering ball cage and is located between the first circular arc track and the second circular arc track. The centering frame is installed in the first shell, and the centering ring is used to contact the rubber core.

[0013] Among them, the inner wall surface of the centering ring is conical, and the cone angle is consistent with the cone angle of the rubber core.

[0014] Furthermore, the first shell includes a centering base and a centering assembly cover, the centering base and the centering assembly cover are fixedly connected, the centering hydraulic cylinder is arranged on the centering base, and the lower centering unit is installed on the centering base.

[0015] The upper shell and the lower shell are detachably connected and are provided with a sealing ring.

[0016] The centering base and the centering assembly cover are connected by threads.

[0017] Wherein, hydraulic channels connected to the centering hydraulic cylinder are provided on the upper shell and the lower shell.

[0018] Wherein, communication channels are provided on the upper shell and the lower shell.

[0019] Furthermore, the self-aligning base and the self-aligning frame are connected via a spline.

[0020] Furthermore, the upper shell is connected to the square bushing through the thrust bearing and the radial bearing assembly, the square bushing is connected to the drill rod, and the drill rod passes through the rubber core and is in close contact with the rubber core.

[0021] In addition, the present invention also discloses a method for adjusting the seal of a rubber core, including using the blowout preventer described above. The specific adjustment method is as follows: S101: Real-time monitoring of the eccentricity of the rubber core. The contact position between the rubber core and the drill pipe is dynamically monitored through displacement sensors evenly distributed on the self-aligning base to obtain the eccentricity data of the rubber core sealing surface. S102: Multi-directional coordinated adjustment of the rubber core position. Based on the feedback signal from the displacement sensor, the piston rods of the evenly distributed self-aligning hydraulic cylinders are independently controlled to extend and retract. The piston rods of the self-aligning hydraulic cylinders directly contact the side of the rubber core, applying radial thrust. The coordinated extension and retraction of the self-aligning hydraulic cylinders compensates for the rubber core eccentricity, ensuring that the rubber core sealing surface evenly holds the drill pipe. S103: Dynamically adapt the sealing angle. The bottom of the rubber core is adaptively adjusted in angle by the lower centering unit. When the centering hydraulic cylinder pushes the top of the rubber core to move, the centering beads move along the first and second circular arc tracks, driving the centering ring to adjust the angle synchronously.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention simplifies the original complex mechanical structure, making processing, installation and maintenance easier. The rotary blowout preventer structure proposed in the present invention adopts a split upper and lower shell design, making the rubber core easy to maintain and disassemble, reducing maintenance time and cost.

[0023] The self-aligning assembly of the present invention adopts a modular design, which improves the stability and adaptability of the device. The sealing mechanism is modularly packaged, and the entire assembly can be removed when replacing the rotary blowout preventer rubber core, allowing timely maintenance of the sealing assembly, thereby enhancing the stability of the rotary blowout preventer.

[0024] The present invention enhances the service life of the rubber core. By using a laser displacement sensor to monitor the sealing position of the rubber core in real time and using a self-aligning hydraulic cylinder to adjust the sealing angle, the stress state of the rotary blowout preventer rubber core can be effectively improved, effectively extending the service life of the rubber core, shortening the drilling time required for rubber core replacement, and thus reducing drilling costs. The present invention uses a pressure sensor to monitor the hydraulic pressure during the compression and rebound of the rubber core during the sealing process, thereby determining the fatigue health of the rubber core and allowing for timely replacement of the rubber core to prevent drilling risks in advance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Schematic diagram of the overall structure of the present invention.

[0027] Figure 2 Schematic diagram of the contact between the rubber core and the drill rod of the present invention.

[0028] Figure 3 It is a schematic diagram of the assembly of the centering base and the lower centering unit of the present invention.

[0029] Figure 4 It is a schematic diagram of the overall structure of the self-aligning assembly of the present invention.

[0030] Figure 5 It is a schematic diagram of the matching relationship between the centering base and the centering frame of the present invention.

[0031] Figure 6 It is a schematic diagram of the overall structure of the self-aligning ring of the present invention.

[0032] Figure 7 It is a schematic diagram of the overall structure of the centering frame of the present invention.

[0033] Figure 8 It is a schematic diagram of the overall structure of the self-aligning ball cage of the present invention.

[0034] Reference numerals: 1-Square bushing, 2-Bearing cover, 3-Radial bearing group, 4-Thrust bearing, 5-Upper housing, 6-Connecting bolts, 7-Self-aligning assembly, 701-Aligning assembly cover, 702-Rubber core, 703-Aligning hydraulic cylinder, 704-Aligning base, 705-Aligning frame, 706-Aligning beads, 707-Aligning ball cage, 708-Aligning ring, 8-Sealing ring, 9-Lower housing, 10-Displacement sensor, 11-Pressure sensor, 12-Upper centering unit, 13-Lower centering unit, 14-First housing, 15-Hydraulic channel, 16-Communication channel, 17-Drill rod, 18-First circular arc track, 19-Second circular arc track. DETAILED DESCRIPTION

[0035] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0036] In the description of the embodiments of the present invention, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present invention.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly specified.

[0038] In the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0039] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above and obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above and obliquely above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0040] The disclosure below provides many different embodiments or examples for implementing different structures of the embodiments of the present invention. In order to simplify the disclosure of the embodiments of the present invention, the components and configurations of specific examples are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. In addition, the embodiments of the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or configurations discussed.

[0041] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0042] See Figures 1-8 This embodiment discloses a blowout preventer, including an upper shell 5 and a lower shell 9 connected to the upper shell 5. This embodiment also includes a self-aligning assembly 7, which is installed between the upper shell 5 and the lower shell 9 and is positioned and fixed by the upper shell 5 and the lower shell 9; the upper shell 5 and the lower shell 9 are connected by connecting bolts 6.

[0043] Among them, the self-aligning assembly 7 includes a first shell 14, a rubber core 702, an upper centering unit 12 and a lower centering unit 13. The first shell 14 is fixedly arranged between the upper shell 5 and the lower shell 9. The rubber core 702 is arranged in the first shell 14, and the rubber core 702 is in contact with the upper centering unit 12 and the lower centering unit 13 installed in the first shell 14; the upper centering unit 12 is used to adjust the position between the upper part of the rubber core 702 and the drill rod 17, and the lower centering unit 13 is used to adjust the position between the lower part of the rubber core 702 and the drill rod 17.

[0044] The upper centering unit 12 includes a displacement sensor 10 and a plurality of centering hydraulic cylinders 703. The plurality of centering hydraulic cylinders 703 are arranged in equal intervals in the first housing 14, and the movable ends of the centering hydraulic cylinders 703 are in contact with the side of the rubber core 702. The displacement sensor 10 is mounted on the inner wall of the first housing 14. The lower centering unit 13 includes a centering frame 705, a centering ring 708, a centering ball cage 707 and a centering bead 706. The inner wall of the centering frame 705 is provided with a first circular arc track 18, and the outer wall of the centering ring 708 is provided with a second circular arc track 19. The second circular arc track 19 cooperates with the first circular arc track 18 on the inner wall of the centering frame 705. The centering bead 706 is installed on the centering ball cage 707 and is located between the first circular arc track 18 and the second circular arc track 19. The centering frame 705 is installed in the first shell 14, and the centering ring 708 is used to contact the rubber core 702.

[0045] The inner wall surface of the centering ring 708 is conical, and the angle of the cone is consistent with the angle of the cone surface of the rubber core 702.

[0046] Furthermore, the first shell 14 includes a centering base 704 and a centering assembly cover 701 , the centering base 704 and the centering assembly cover 701 are fixedly connected, the centering hydraulic cylinder 703 is arranged on the centering base 704 , and the lower centering unit 13 is installed on the centering base 704 .

[0047] The upper shell 5 and the lower shell 9 are detachably connected and are provided with a sealing ring 8 .

[0048] Furthermore, the centering base 704 and the centering assembly cover 701 are connected by threads.

[0049] Furthermore, a hydraulic channel 15 connected to the centering hydraulic cylinder 703 is provided on the upper shell 5 and the lower shell 9.

[0050] Furthermore, a communication channel 16 is provided on the upper shell 5 and the lower shell 9 .

[0051] Furthermore, the centering base 704 and the centering frame 705 are connected via a spline.

[0052] Furthermore, the upper shell 5 is connected to the square bushing 1 through the thrust bearing 4 and the radial bearing group 3. The square bushing 1 is connected to the drill rod 17. The drill rod 17 passes through the rubber core 702 and is in close contact with the rubber core 702. The radial bearing group 3 is fixed with the bearing cover 2.

[0053] Furthermore, the hydraulic channel 15 is connected to a pressure sensor 11 .

[0054] The present invention monitors the eccentricity of the rubber core 702 through a displacement sensor 10, adjusts the eccentric position of the rubber core 702 using a centering hydraulic cylinder 703, and optimizes the sealing surface of the rubber core 702 in real time, thereby improving the service life of the rubber core 702 of the rotary blowout preventer and effectively extending the service life of the rubber core 702. The hydraulic pressure during the compression and rebound of the rubber core 702 during the sealing process is monitored by the pressure sensor 11, and the fatigue health of the rubber core 702 is determined, so that the rubber core 702 can be replaced in time. This not only ensures drilling safety, but also shortens the drilling time caused by replacing the rubber core 702 and reduces drilling costs.

[0055] In order to facilitate those skilled in the art to further understand the present invention, the present invention is further elaborated below.

[0056] A self-diagnostic modular rotary blowout preventer, wherein a square bushing 1 is connected to a thrust bearing 4 and a radial bearing assembly 3 with an upper shell 5. The upper shell 5 and the lower shell 9 are fixedly connected by connecting bolts 6, so that the upper shell 5 and the lower shell 9 can be disassembled, facilitating the rapid replacement of the self-aligning assembly 7.

[0057] The square bushing 1 is a steel part with an upper portion and a lower portion that is round. It is sleeved on the drill pipe 17 and is driven by a rotary table or a top drive during rotary drilling to apply torque to the drill string.

[0058] A sealing ring 8 is provided between the upper shell 5 and the lower shell 9 , and a shoulder is provided inside the upper shell 5 for installation and positioning of the self-aligning assembly 7 .

[0059] A communication channel 16 is provided inside the upper shell 5 and the lower shell 9 to realize the wiring of the displacement sensor 10; a hydraulic channel 15 is provided inside the upper shell 5 and the lower shell 9; The self-aligning assembly 7 is located between the upper shell 5 and the lower shell 9, and is limited from above by the internal shoulders of the upper shell 5 and the lower shell 9, and is fixedly connected by bolts.

[0060] The centering frame 705 is installed inside the centering base 704 through the positioning shoulder. The centering frame 705 and the centering ring 708 are connected through the centering beads 706 and the tracks inside the centering frame 705 (the first arc track 18 and the second arc track 19). The centering assembly cover 701 is connected to the centering base 704 through screws.

[0061] The centering beads 706 are located between the first arc-shaped track 18 and the second arc-shaped track 19 , so that the centering ring 708 can deflect at multiple angles relative to the centering frame 705 .

[0062] The displacement sensor 10 is a laser displacement sensor 10 , and is mounted on the self-aligning base 704 through threads, and is used to monitor the rebound pressure of the rubber core 702 to determine the fatigue state.

[0063] During operation, the square bushing 1 is connected to the drill pipe 17 via API threads and is driven by the upper rotary table or top drive for rotary drilling. During pressurized operations, because the pressure in the wellbore is slightly lower than the formation pressure, to ensure drilling safety, a radial thrust is applied to the aligning hydraulic cylinder 703 through the hydraulic flow channel on the side of the lower housing 9. The piston rod of the aligning hydraulic cylinder 703 is pushed outward, causing the rubber core 702 to deform radially and "hold" the drill pipe 17. During drilling, the square bushing 1, drill pipe 17, and the rotary blowout preventer rubber core 702 rotate in coordination, while the upper housing 5, lower housing 9, aligning hydraulic cylinder 703, aligning assembly cover 701, and aligning base 704 remain stationary.

[0064] Six self-aligning hydraulic cylinders 703 are evenly distributed in the circumferential direction on the upper part of the self-aligning assembly 7. The piston rod ends of the self-aligning hydraulic cylinders 703 are arc-shaped structures and contact the cylindrical end surface of the rubber core 702.

[0065] When the self-aligning assembly 7 is in operation, hydraulic oil enters the rodless cavity end surface of the self-aligning hydraulic cylinder 703 through the hydraulic passage 15 of the lower housing 9, pushing the piston rod of the self-aligning hydraulic cylinder 703 out. A pressurized port is provided in the rodless cavity of the self-aligning hydraulic cylinder 703, connecting to the hydraulic passage 15 of the upper housing 5. A pressure relief port is provided in the rod cavity, leading to the sealing area of ​​the rubber core 702. The end of the self-aligning hydraulic cylinder piston rod is curved and contacts the cylindrical surface of the drill pipe 17.

[0066] When the sealing end surface of the rubber core 702 and the contact surface of the drill pipe 17 are offset, the position of the rubber core 702 is coordinated by the six centering hydraulic cylinders 703 to ensure that the rubber core 702 is always in uniform contact with the cylindrical end surface of the drill pipe 17, thereby improving the stress state of the rubber core 702 during pressure drilling and extending the service life of the rubber core 702.

[0067] During pressure relief, the pressure in the hydraulic channel 15 is closed, and the rubber core 702 is reset under the action of elastic force, pushing the self-aligning hydraulic cylinder 703 to move, and the hydraulic oil is discharged. A pressure sensor 11 is installed on the outside of the lower shell 9 to monitor the pressure of the hydraulic oil inlet and outlet, so as to determine whether the rubber core 702 has fatigue failure and replace the rubber core 702 in advance to prevent well control accidents.

[0068] In the centering assembly, six laser displacement sensors 10 are evenly distributed in the circumferential direction below the centering hydraulic cylinder 703. The laser displacement sensor 10 is installed on the centering base 704 through threads, and the communication line and power line are connected to the ground device through the communication channel 16 on the side of the lower shell 9.

[0069] During operation, the sealing angle of the rubber core 702 is dynamically monitored by the laser displacement sensor 10, and the signal is transmitted to the ground driller's platform. According to the position of the rubber core 702, the centering hydraulic cylinder 703 is used to adjust the sealing of the rubber core 702 in real time.

[0070] The bottom of the aligning base 704 is provided with a shoulder for positioning and installing the aligning frame 705. The aligning base 704 is provided with an internal spline groove, and the outer circle of the aligning frame 705 is provided with an external spline to cooperate with it. Six circular holes are evenly distributed on the aligning ball cage 707, and the aligning beads 706 are installed in the circular holes. The inner wall of the aligning frame 705 is processed with an arc-shaped track. The outer wall of the aligning ring 708 is provided with an arc-shaped track to cooperate with the track on the inner wall of the aligning frame 705, so that the aligning beads 706 run in the track. The inner wall of the aligning ring 708 is conical, and the cone angle is consistent with the cone angle of the rubber core 702. During operation, the piston rod of the aligning hydraulic cylinder pushes the top position of the rubber core 702, and the aligning beads 706 in the bottom area move in the track between the aligning frame 705 and the aligning ring 708 to adjust the sealing angle of the rubber core 702.

[0071] The signal of the displacement sensor 10 is transmitted to the ground control system, and after being processed by the PID algorithm, an independent control instruction of each self-aligning hydraulic cylinder 703 is generated, and the extension and contraction amount of the piston rod is adjusted through the hydraulic channel 15.

[0072] This embodiment also discloses a method for adjusting the seal of the rubber core 702, including using the blowout preventer described above. The specific adjustment method is as follows: S101: Real-time monitoring of the eccentricity of the rubber core 702. The contact position between the rubber core 702 and the drill rod 17 is dynamically monitored by the displacement sensors 10 evenly distributed on the centering base 704 to obtain the eccentricity data of the sealing surface of the rubber core 702. S102: The position of the rubber core 702 is adjusted in a multi-directional coordinated manner. Based on the feedback signal from the displacement sensor 10, the piston rods of the evenly distributed centering hydraulic cylinders 703 are independently controlled to extend and retract. The piston rods of the centering hydraulic cylinders 703 directly abut the side of the rubber core 702, exerting radial thrust. The coordinated extension and retraction of the centering hydraulic cylinders 703 compensates for the eccentricity of the rubber core 702, so that the sealing surface of the rubber core 702 evenly holds the drill pipe 17. S103: Dynamically adapt the sealing angle. The bottom of the rubber core 702 is adaptively changed in angle through the lower centering unit 13. When the centering hydraulic cylinder 703 pushes the top of the rubber core 702 to move, the centering beads 706 move along the first circular arc track 18 and the second circular arc track 19, driving the centering ring 708 to adjust the angle synchronously.

[0073] In specific implementation, the bottom of the rubber core 702 changes its angle adaptively through the first arc track 18 and the second arc track 19 following mechanism: The conical inner wall of the centering ring 708 fits the conical surface of the rubber core 702, and their angles are consistent; The centering beads 706 roll between the first arc-shaped track 18 of the centering frame 705 and the second arc-shaped track 19 of the centering ring 708; When the centering hydraulic cylinder 703 pushes the top of the rubber core 702 to move, the centering beads 706 move along the first arc track 18 and the second arc track 19, driving the centering ring 708 to adjust its angle synchronously.

[0074] In practice, the outer wall of the centering frame 705 is splined to the centering base 704. During operation, the centering frame 705 and the centering base 704 are connected and maintain stability. The first arc-shaped track 18 provided on the inner wall of the centering frame 705 adopts a curved track design. The number of the first arc-shaped tracks 18 on the centering frame 705 is the same as the number of the second arc-shaped tracks 19 on the centering ring 708, both of which are six.

[0075] During the installation process, the centering bead 706 is installed between the first arc-shaped track 18 and the second arc-shaped track 19 . During the centering operation of the rotary blowout preventer, the centering bead 706 is in conjugate contact with the first arc-shaped track 18 and the second arc-shaped track 19 .

[0076] The first and second circular-arc tracks 18, 19 are elliptical in shape, with the eccentricity of the ellipse determined by the maximum operating angle of the universal joint. A larger angle requires a greater eccentricity. To ensure the self-aligning assembly 7 maintains a certain load-bearing capacity during BOP alignment, the angle between the normal direction of the contact point between the centering bead 706 and the first and second circular-arc tracks 18, 19 and the axis is controlled to be between 6 and 12 degrees. The radius of curvature is larger than the radius of the centering bead 706 to provide clearance for grease and allow for minor misalignment.

[0077] In some preferred embodiments, the process further includes S104: monitoring the oil pressure change in the hydraulic channel 15 through the pressure sensor 11, comparing the rebound pressure of the rubber core 702 with the fatigue threshold, and determining the elastic failure risk.

[0078] The oil pressure change of the hydraulic channel 15 is monitored in real time by the pressure sensor 11: During sealing: record the pressurized pressure of the self-aligning hydraulic cylinder 703; During pressure relief: monitor the pressure of the hydraulic oil discharged from the self-aligning hydraulic cylinder 703 by the rebound of the rubber core 702; Compare the pressure data with the fatigue threshold to determine the risk of elastic failure of the rubber core 702 and issue an early warning for replacement.

[0079] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A blowout preventer, comprising an upper shell and a lower shell connected to the upper shell, characterized in that: Also included is a self-aligning assembly, which is installed between the upper shell and the lower shell and is positioned and fixed by the upper shell and the lower shell; Among them, the self-aligning assembly includes a first shell, a rubber core, an upper centering unit and a lower centering unit. The first shell is fixedly arranged between the upper shell and the lower shell. The rubber core is arranged in the first shell, and the rubber core is in contact with the upper centering unit and the lower centering unit installed in the first shell. The upper centering unit is used to adjust the position between the upper part of the rubber core and the drill rod, and the lower centering unit is used to adjust the position between the lower part of the rubber core and the drill rod.

2. A blowout preventer according to claim 1, characterized in that: The upper centering unit includes a displacement sensor and a plurality of centering hydraulic cylinders. The plurality of centering hydraulic cylinders are arranged in the first shell at equal intervals, and the movable ends of the centering hydraulic cylinders are in contact with the side surfaces of the rubber core.

3. A blowout preventer according to claim 2, characterized in that: The lower centering unit includes a centering frame, a centering ring, a centering ball cage and a centering bead. The inner wall of the centering frame is provided with a first circular arc track, and the outer wall of the centering ring is provided with a second circular arc track. The second circular arc track cooperates with the first circular arc track on the inner wall of the centering frame. The centering bead is installed on the centering ball cage and is located between the first circular arc track and the second circular arc track. The centering frame is installed in the first shell, and the centering ring is used to contact the rubber core.

4. A blowout preventer according to claim 3, characterized in that: The first shell includes a centering base and a centering assembly cover. The centering base and the centering assembly cover are fixedly connected. The centering hydraulic cylinder is arranged on the centering base, and the lower centering unit is installed on the centering base.

5. A blowout preventer according to claim 1, characterized in that: The upper shell and the lower shell are detachably connected and are provided with a sealing ring.

6. A blowout preventer according to claim 2, characterized in that: The upper shell and the lower shell are provided with hydraulic channels connected with the center-aligning hydraulic cylinder.

7. A blowout preventer according to claim 1, characterized in that: Communication channels are arranged on the upper shell and the lower shell.

8. A blowout preventer according to claim 4, characterized in that: The self-aligning base and the self-aligning frame are connected by splines.

9. A blowout preventer according to any one of claims 1 to 8, characterized in that: The upper shell is connected to the square bushing through a thrust bearing and a radial bearing assembly. The square bushing is connected to the drill rod. The drill rod passes through the rubber core and is in close contact with the rubber core.

10. A method for adjusting the seal of a rubber core, characterized in that: The blowout preventer according to claim 4 is used, and the specific adjustment method is as follows: S101: Real-time monitoring of the eccentricity of the rubber core. The contact position between the rubber core and the drill pipe is dynamically monitored through displacement sensors evenly distributed on the self-aligning base to obtain the eccentricity data of the rubber core sealing surface. S102: Multi-directional coordinated adjustment of the rubber core position. Based on the feedback signal from the displacement sensor, the piston rods of the evenly distributed self-aligning hydraulic cylinders are independently controlled to extend and retract. The piston rods of the self-aligning hydraulic cylinders directly contact the side of the rubber core, applying radial thrust. The coordinated extension and retraction of the self-aligning hydraulic cylinders compensates for the rubber core eccentricity, ensuring that the rubber core sealing surface evenly holds the drill pipe. S103: Dynamically adapt the sealing angle. The bottom of the rubber core is adaptively adjusted in angle by the lower centering unit. When the centering hydraulic cylinder pushes the top of the rubber core to move, the centering beads move along the first and second circular arc tracks, driving the centering ring to adjust the angle synchronously.

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