Electric lifting anti-overflow mechanism

Abstract

The invention discloses an electric lifting anti-overflow mechanism and relates to blowout prevention technology, the electric lifting anti-overflow mechanism comprises a blowout preventer body, a drilling tool and a lifting assembly, a first sealing ring is slidably mounted in the blowout preventer body, a second sealing ring is further fixed in the blowout preventer body, and the first sealing ring and the second sealing ring are in concave-convex sealing fit. The first sealing ring is arranged on a drilling tool in a sleeving manner, and the driving assembly is used for driving the first sealing ring to move axially; according to the electric lifting anti-overflow mechanism, when a drilling tool rotates, the first sealing ring makes contact with the drilling tool in a dynamic sealing mode, and when overflow is detected, the first sealing ring is driven by the driving assembly to move in the axial direction, so that the first sealing ring is clamped into the second sealing ring to form concave-convex fit for sealing; the first sealing ring is of a complete annular structure and rotates along with the drilling tool, so that damage caused by sudden contact with the drilling tool is avoided, and the sealing structure is protected while the sealing effect is ensured.

Description

Technical Field

[0001] The present invention relates to blowout prevention technology, and more particularly to an electric lifting anti-overflow mechanism. Background Art

[0002] The anti-overflow mechanism is a safety device for preventing blowouts or medium leakage, usually installed in the wellhead system. Its main functions are to monitor the wellbore pressure, control the fluid flow, and promptly seal the wellhead to prevent the overflow from evolving into a blowout accident and ensure the operation safety. Currently, when domestic oilfields conduct injection well tests and injection water volume allocation, it is necessary to lower the test and allocation instrument by cable to the target layer. This must be accomplished with the aid of an injection anti-overflow mechanism. When lowering or lifting the anti-overflow mechanism, hydraulic lifting can be used to lift the anti-overflow mechanism. The anti-overflow mechanism generally includes: a wellhead connection mechanism, a lifting mechanism, a blowout preventer pipe, and a blowout preventer. Among them, the blowout preventer is the core component of the anti-overflow mechanism, which can quickly close the wellhead in an emergency to prevent the ejection of high-pressure oil and gas and other fluids. The main types of blowout preventers include ram blowout preventers, annular blowout preventers, and rotary blowout preventers. The ram blowout preventer drives the ram to close or open the wellhead by hydraulic pressure, while the annular blowout preventer uses a rubber core to seal the annular space to achieve well sealing, and the rotary blowout preventer uses a rubber core or a sealing ring to seal the drill string while rotating.

[0003] Currently, when domestic oilfields conduct injection well tests and injection water volume allocation, it is necessary to lower the test and allocation instrument by cable to the target layer. During this process, it is necessary to rely on the wellhead blowout prevention system to complete the lowering and lifting of the instrument. The wellhead blowout prevention system generally includes: a wellhead connection mechanism, a lifting mechanism, and a blowout prevention device (including a blowout preventer pipe and a blowout preventer head). When lowering and lifting the blowout prevention device, generally, crane-assisted lifting and hydraulic-assisted lifting can be used. In the prior art, when hydraulically lifting the blowout prevention device, the test instrument and the counterweight must be connected and placed in the blowout preventer pipe together, and the lifting mechanism uses a hydraulic mechanism to push and lower from one end (the lower part), resulting in high construction difficulty and instability, and there are certain safety hazards.

[0004] For a patent with the authorization announcement number CN106639959B, the authorization announcement date of March 21, 2023, and the name of Blowout Preventer Actuator and Blowout Preventer, in this blowout preventer actuator, the fixed component includes a bushing fixed to the blowout preventer; the execution component includes a first execution part and a second execution part, the second execution part is connected to the bushing and can drive the first execution part to rotate; the movement component includes a fixed part, a movement part and a connection part, the fixed part is rotatably sleeved on the bushing, the movement part is rotatably sleeved on the second execution part, and the connection part is used to drive the movement part to move away from or close to the fixed part and make the second execution part slide along the bushing. During the rotation of the blowout preventer applying this actuator, the movement component is stationary relative to the blowout preventer body. The movement component can drive the second execution part to slide along the bushing, and convert the linear movement of the second execution part into the rotation of the first execution part, so that the first execution part can open or close the blowout preventer when the top drive main shaft rotates, meeting the usage requirements.

[0005] Another example is a patent with the authorization announcement number CN114396241B, the authorization announcement date of June 10, 2022, and the name of A Double-Layer Sealed Spherical Rubber Core and Annular Blowout Preventer. The spherical rubber core includes a spherical rubber core body, a pushing mechanism and multiple support ribs. The spherical rubber core body includes an annular chassis and multiple rubber teeth circumferentially arranged on the top of the annular chassis; the support ribs are spaced between two rubber teeth, and the bottom of the support ribs is connected to the annular chassis through a spring assembly; the pushing mechanism includes multiple sealing heads and multiple pushing components, the sealing heads and the pushing components are connected through connecting rods, the multiple sealing heads are evenly distributed along the inner wall of the annular chassis, the pushing components are located outside the annular chassis, and the connecting rods are slidably fitted in the annular chassis. When the spherical rubber core moves upward under the push of the piston, the connecting rods can move inwards, and the multiple sealing heads gather around the drill pipe. This increases the connection stability of the support ribs, prevents the support ribs from falling into the well, and at the same time can make the support ribs quickly return to their positions; a double-layer sealing structure is set to increase the sealing performance of the permanent packer rubber barrel under complex working conditions.

[0006] The deficiencies of the prior art are that in oil extraction, generally, the radial movement of multiple sealing structures is used to make them gather and press against the drill pipe to form a whole for sealing. However, due to the fact that overflow is often sudden, when the sealing structure presses against the drill pipe, the drill pipe is still in a relatively fast rotation process. At this time, the drill pipe is likely to impact the sealing structure and the connecting parts and cause them to be damaged. Summary of the Invention

[0007] The purpose of the present invention is to provide an electric lifting anti-overflow mechanism to solve the above deficiencies in the prior art.

[0008] To achieve the above purpose, the present invention provides the following technical solutions: An electric lifting anti-overflow mechanism, comprising a blowout preventer body, a drill string movably passing through the blowout preventer body, and a lifting assembly for moving the blowout preventer body. The lifting assembly includes a union connected to the wellhead and a lifting motor fixed on the union. A first sealing ring is slidably installed in the blowout preventer body, and a second sealing ring is also fixed in the blowout preventer body. An uneven sealing fit is formed between the first sealing ring and the second sealing ring. The first sealing ring is sleeved on the drill string, and a driving assembly is further included for driving the first sealing ring to move axially. When overflow is detected, the first sealing ring is driven by the driving assembly to move axially and snap into the second sealing ring to form a seal.

[0009] In the initial state of the above-mentioned electric lifting anti-overflow mechanism, there is a certain distance between the first sealing ring and the second sealing ring.

[0010] In the above-mentioned electric lifting anti-overflow mechanism, a circular hole is opened inside the second sealing ring. The circular hole is used for fluid passage. The shape of the side wall of the circular hole is the same as that of the side wall of the first sealing ring, and the diameter of the circular hole is larger than the diameter of the drill string.

[0011] In the above-mentioned electric lifting anti-overflow mechanism, the side wall of the circular hole is a stepped structure, and the side wall of the first sealing ring is also a stepped structure.

[0012] In the above-mentioned electric lifting anti-overflow mechanism, the blowout preventer body is of a tower-shaped structure as a whole. The blowout preventer body includes a first cylinder and a second cylinder connected to each other. The first cylinder is located above the second cylinder, and the diameter of the first cylinder is smaller than that of the second cylinder. The first sealing ring is slidably arranged in the first cylinder.

[0013] In the above-mentioned electric lifting anti-overflow mechanism, the driving assembly includes two connecting shafts slidably passing through the upper end of the first cylinder. The two connecting shafts are connected by a driving ring. The central axis of the driving ring coincides with the central axis of the first cylinder. Two oppositely arranged driving cylinders are installed at the upper end of the first cylinder, and the movable ends of the driving cylinders are connected to the driving ring.

[0014] In the above-mentioned electric lifting anti-overflow mechanism, a dynamic sealing assembly is arranged on the inner side wall of the first sealing ring. The first sealing ring contacts the drill string through the dynamic sealing assembly.

[0015] In the above-mentioned electric lifting anti-overflow mechanism, the dynamic sealing assembly includes an annular groove opened on the inner wall of the first sealing ring. An annular mounting member is rotatably installed in the annular groove, and a sealing ring is movably sleeved in the annular mounting member.

[0016] The above-mentioned electric lifting anti-overflow mechanism, the cross-section of the sealing ring is circular.

[0017] In the above-mentioned electric lifting anti-overflow mechanism, a spring rod is also connected between the connecting shaft and the driving ring.

[0018] In the above technical solution, the present invention provides an electric lifting anti-overflow mechanism, including a blowout preventer body, a first sealing ring and a second sealing ring. The first sealing ring is sleeved on the drill pipe to form a dynamic seal. When the drill pipe rotates, the first sealing ring contacts the drill pipe dynamically. When overflow is detected, the first sealing ring is driven to move axially through the driving component, so that the first sealing ring is clamped into the second sealing ring to form a concave-convex fit for sealing. In this way, the first sealing ring is originally a complete ring structure and rotates with the drill pipe, so it will not suddenly contact the drill pipe and cause damage, while ensuring the sealing effect, protecting the sealing structure and its connecting parts. Brief Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings.

[0020] Figure 1 It is a three-dimensional structure schematic diagram of the electric lifting anti-overflow mechanism provided by an embodiment of the present invention.

[0021] Figure 2 It is a partial three-dimensional structure schematic diagram of the electric lifting anti-overflow mechanism provided by an embodiment of the present invention.

[0022] Figure 3 It is a schematic diagram of the fluid movement direction inside the electric lifting anti-overflow mechanism provided by an embodiment of the present invention.

[0023] Figure 4 It is a cross-sectional view of the electric lifting anti-overflow mechanism provided by another embodiment of the present invention.

[0024] Figure 5 For the present invention Figure 4 Local enlarged view at X.

[0025] Figure 6 For the present invention Figure 4 Local enlarged view at Y.

[0026] Figure 7 It is a cross-sectional view of the electric lifting anti-overflow mechanism provided by still another embodiment of the present invention.

[0027] Figure 8 For the present invention Figure 7Partial enlarged view at Z.

[0028] Description of reference numerals: 1. Blowout preventer body; 11. First cylinder; 12. Second cylinder; 2. Drill string; 3. First sealing ring; 31. Limit hole; 32. Dynamic sealing assembly; 321. Annular groove; 322. Annular mounting part; 323. Sealing ring; 4. Second sealing ring; 41. Circular hole; 42. Compression locking assembly; 421. Through hole; 422. Compression block; 423. Limit spring; 424. Connection hole; 425. Locking block; 426. Connection spring; 43. Disconnection limit assembly; 431. Disconnection opening; 432. Connecting rod; 433. Relief hole; 434. Elastic limit rod; 5. Driving assembly; 51. Connecting shaft; 52. Driving ring; 53. Driving cylinder. Detailed implementation manners

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] As Figures 1-8 shown, an electric lifting anti-overflow mechanism provided by an embodiment of the present invention includes a blowout preventer body 1, a drill string 2 that movably penetrates the blowout preventer body 1, and a lifting assembly for moving the blowout preventer body 1. The lifting assembly includes a union connected to the wellhead and a lifting motor fixed on the union. A first sealing ring 3 is slidably installed in the blowout preventer body 1, and a second sealing ring 4 is also fixed in the blowout preventer body 1. An uneven sealing fit is formed between the first sealing ring 3 and the second sealing ring 4. The first sealing ring 3 is sleeved on the drill string 2, and a driving assembly 5 for driving the first sealing ring 3 to perform axial movement is further included; when overflow is detected, the first sealing ring 3 is driven by the driving assembly 5 to perform axial movement and is clamped into the second sealing ring 4 to form a seal.

[0031] Specifically, in this embodiment, the blowout preventer body 1 is mainly used to provide a passage for the movement of fluid (mainly oil during drilling) and install an anti-overflow structure. The preferred shape is a tower structure, and a fluid movement passage is provided inside it. An inlet is provided at the bottom of the blowout preventer body 1 for the fluid to enter, and an outlet is provided at the upper end of the blowout preventer body 1 for the fluid to be output. The diameters of both the inlet and the outlet are larger than the diameter of the drill string 2. Preferably, the blowout preventer body 1 can be arranged at the contact position between the wellhead and the drill string 2; the drill string 2 includes a drill bit and a drill pipe. In this embodiment, mainly the drill pipe movably penetrates through the blowout preventer body 1. The drill pipe is a cylindrical structure. It should be noted that the drill string 2 in this embodiment can also be a tubular structure such as a blowout preventer pipe for transporting fluid; an overflow test instrument is also connected below the blowout preventer body 1. The overflow test instrument is a prior art and will not be elaborated. The lifting assembly (not shown in the figure) is used to lift and lower the blowout preventer body 1 and the overflow test instrument to ensure that the blowout preventer body 1 and the overflow test instrument can accurately reach the height position required for work. The lifting assembly includes a union connected to the wellhead. A lifting motor is fixed on the union. A lifting lead screw is connected to the output shaft of the lifting motor. A connecting screw ring is threadedly connected to the lifting lead screw. The connecting screw ring is fixedly connected to the blowout preventer pipe. The blowout preventer pipe can only slide along the wellhead direction. When the lifting motor is started, the lifting lead screw rotates synchronously, thereby driving the connecting screw ring to move. Also, since the connecting screw ring is fixedly connected to the blowout preventer pipe and the blowout preventer pipe can only slide along the wellhead direction, the blowout preventer pipe also moves down and up along the wellhead, thus completing the lowering and lifting of the blowout preventer body 1 and the overflow test instrument; both the first sealing ring 3 and the second sealing ring 4 are annular block structures. In addition to slidingly arranged inside the blowout preventer body 1, the first sealing ring 3 also sleeves on the drill pipe. It should be noted that the first sealing ring 3 and the drill pipe are in dynamic sealing. The diameter of the first sealing ring 3 is smaller than that of the second sealing ring 4. An uneven fit is formed between the outer side wall of the first sealing ring 3 and the inner side wall of the second sealing ring 4. When the first sealing ring 3 moves downward and completely contacts the second sealing ring 4, the first sealing ring 3 is blocked by the second sealing ring 4 and cannot continue to move downward. At this time, an uneven sealing fit is formed between the two; in addition, in the initial state, there is a certain distance between the first sealing ring 3 and the second sealing ring 4 in the vertical direction. The passage formed by this distance and the blowout preventer body 1 is used to pass the fluid. In this embodiment, the fluid enters from the inlet at the bottom of the blowout preventer body 1, then passes through the second sealing ring 4 and enters the area between the first sealing ring 3 and the second sealing ring 4, and finally is output from the outlet through the first sealing ring 3. That is to say, the blowout preventer body 1 is equivalent to being arranged in the fluid flow path and does not change the overall movement direction of the fluid;Specifically during operation, when the overflow detection instrument detects an overflow, the driving component 5 drives the first sealing ring 3 to move axially and snap into the second sealing ring 4 to form a concave-convex mating seal to block the movement of the fluid. During this process, the first sealing ring 3 always adheres to the surface of the drill tool 2 for dynamic sealing, and thus will not suddenly contact the rotating drill tool 2 when an overflow occurs, causing damage. While ensuring the sealing effect, the sealing structure is protected.

[0032] In another embodiment provided by the present invention, a circular hole 41 is opened inside the second sealing ring 4. The circular hole 41 is used to pass the fluid and form a concave-convex mating with the first sealing ring 3. The side wall shape of the circular hole 41 is the same as the side wall shape of the first sealing ring 3. The diameter of the circular hole 41 is larger than the diameter of the drill tool 2. The side wall of the circular hole 41 is a stepped structure, and the side wall of the first sealing ring 3 is also a stepped structure. The diameter of the upper side wall of the circular hole 41 is larger than the diameter of the lower side wall, and the diameter of the upper side wall of the first sealing ring 3 is larger than the diameter of the lower side wall. In this way, a concave-convex mating is formed to achieve sealing and cut off the overflow.

[0033] In another embodiment provided by the present invention, the blowout preventer body 1 is an overall tower-shaped structure with a smaller upper part and a larger lower part. The blowout preventer body 1 includes a connected first cylinder 11 and a second cylinder 12. The first cylinder 11 is located above the second cylinder 12, and the diameter of the first cylinder 11 is smaller than that of the second cylinder 12. The first sealing ring 3 is slidably arranged in the first cylinder 11, the second sealing ring 4 is fixedly arranged in the second cylinder 12, the inlet is opened at the bottom of the second cylinder 12, and the outlet is opened at the top of the first cylinder 11. Obviously, the blowout preventer body 1 is designed in this way to cooperate with the work of the first sealing ring 3 and the second sealing ring 4 and provide an installation space for the driving component 5.

[0034] In yet another embodiment provided by the present invention, the driving assembly 5 includes two connecting shafts 51 slidably inserted through the upper end of the first cylinder 11. A sliding seal is provided between the connecting shafts 51 and the first cylinder 11. The two connecting shafts 51 are connected by a driving ring 52. The driving ring 52 is also of an annular structure. The central axis of the driving ring 52 coincides with the central axis of the first cylinder 11. Moreover, the inner diameter of the driving ring 52 is larger than the diameter of the drill pipe and also larger than the diameter of the outlet. Two oppositely arranged driving cylinders 53 are installed at the upper end of the first cylinder 11. The movable ends of the driving cylinders 53 are connected to the driving ring 52. When the overflow detection instrument detects an overflow, the driving ring 52 is driven to move downward by the driving cylinders 53, so that the driving ring 52 pushes the two connecting shafts 51 to move downward and drives the first sealing ring 3 to move axially downward. When the first sealing ring 3 is stuck in the second sealing ring 4 to form a concave-convex fit and seal, the operation of the driving cylinders 53 is stopped and a certain pressure is maintained. In this way, the cutting of the fluid movement is maintained. A spring rod is also connected between the connecting shaft 51 and the driving ring 52. The spring rod is mainly used to buffer the daily flow impact and prevent the daily fluid impact from affecting the operation of the driving cylinders 53. When the first sealing ring 3 is pushed into contact with the second sealing ring 4, due to the large impact force of the overflow, when the first sealing ring 3 is pushed to move downward, the spring rod is gradually compressed to the elastic limit. At this time, the first sealing ring 3 forms a concave-convex fit and seal with the second sealing ring 4, and the spring rod will no longer perform elastic movement, so it will not affect the relative positions of the first sealing ring 3 and the second sealing ring 4, thereby ensuring the sealing and anti-overflow effect.

[0035] Obviously, the movement of the drill rod is a combination of axial downward movement and its own rotation, and the first sealing ring 3 needs to be dynamically sealed on the drill rod. This is because the axial movement of the first sealing ring 3 is not controlled by the drill rod but by the driving cylinder 53. When the first sealing ring 3 performs the anti-overflow action, it actually slides relative to the drill rod. However, the relative sliding between the first sealing ring 3 and the drill rod is compared with the relative rotation between the first sealing ring 3 and the drill rod. Obviously, the relative rotation has a greater impact on the first sealing ring 3. This is because the drill rod needs to maintain a higher rotation speed, but the axial movement speed is relatively stable. For this reason, this embodiment provides a dynamic sealing structure to solve the above technical problems. A dynamic sealing assembly 32 is provided on the inner side wall of the first sealing ring 3, and the first sealing ring 3 contacts the drill tool 2 through the dynamic sealing assembly 32; The dynamic seal assembly 32 includes an annular groove 321 provided on the inner wall of the first sealing ring 3, an annular mounting piece 322 is rotatably mounted in the annular groove 321, and a sealing ring 323 is sleeved in the annular mounting piece 322; the cross-section of the sealing ring 323 is preferably circular, so that the sealing ring 323 can form a uniform pressure on the drill pipe surface, and the inner wall of the sealing ring 323 is pressed tightly against the drill pipe, so that when the drill pipe rotates, the sealing ring 323 also rotates and drives the annular mounting piece 322 to rotate in the annular groove 321, so that the speed of the sealing ring 323 is kept consistent with the speed of the drilling tool 2 as much as possible, so that when overflow occurs, direct pressing contact with the high-speed rotating drill pipe can be avoided. In addition, it is obvious that the relative sliding between the sealing ring 323 and the drill pipe is stable and slow, and the wear generated in this case is relatively acceptable.

[0036] Furthermore, when overflow occurs, the driving cylinder 53 immediately drives the driving ring 52 to move downward, and the first sealing ring 3 is axially moved accordingly to form a concave-convex fit with the second sealing ring 4, cutting off the path for the fluid to continue moving upward. However, there is still a tendency for the overflow to spray outwards, that is, a relatively large pressure will still be exerted on the first sealing plate. If the sealing is completely dependent on the power of the driving cylinder 53, a relatively large load will be imposed on the driving cylinder 53. However, if the first sealing ring 3 is directly locked to the second sealing ring 4, subsequent operations cannot be carried out. Therefore, this embodiment provides a further solution to solve the above technical problems; a pressure-bearing locking assembly 42 is installed on the second sealing ring 4, and a limiting hole 31 corresponding to the pressure-bearing locking assembly 42 is provided on the outer side wall of the first sealing ring 3. When the second sealing ring 4 is subjected to a relatively large pressure, the limiting hole 31 can be limited by the pressure-bearing locking assembly 42; the pressure-bearing locking assembly 42 includes a through hole 421 provided on the second sealing ring 4, the through hole 421 penetrates the second sealing ring 4 and is parallel to the central axis of the second sealing ring 4, a pressure-bearing block 422 is slidably installed in the through hole 421, the pressure-bearing block 422 is a square block structure, the pressure-bearing block 422 performs dynamic sealing on the through hole 421, a limiting spring 423 is further connected between the pressure-bearing block 422 and the through hole 421, the limiting spring 423 is used to maintain the initial position of the pressure-bearing block 422, the upper end surface of the pressure-bearing block 422 is an inclined surface. In addition, a connecting hole 424 is also provided on the inner wall of the circular hole 41, the extending direction of the connecting hole 424 is perpendicular to the central axis of the second sealing ring 4, one end of the connecting hole 424 penetrates the circular hole 41, and the other end of the connecting hole 424 communicates with the through hole 421, a locking block 425 is slidably installed in the connecting hole 424, a connecting spring 426 is connected between the locking block 425 and the connecting hole 424, the connecting spring 426 is used to maintain the initial position of the locking block 425, the locking block 425 is also a square block structure, and the locking block 425 and the limiting hole 31 are arranged in a corresponding and matching manner, one end of the locking block 425 close to the pressure-bearing block 422 is an inclined surface, the inclined surface of the locking block 425 is attached to the inclined surface of the pressure-bearing block 422. When the pressure-bearing block 422 moves upward, the locking block 425 can be squeezed by the inclined surface on the pressure-bearing block 422, so that the locking block 425 extends out of the connecting hole 424. In the initial state, the fluid in the blowout preventer body 1 is in a normal flowing state, and the liquid pressure in the blowout preventer body 1 is also in a normal state. At this time, the pressure fluctuation received by the pressure-bearing block 422 is small, and the upward movement amplitude is small, so the locking block 425 cannot be squeezed to extend out; more preferably, one side of the upper end of the locking block 425 close to the circular hole 41 is also an inclined surface. The purpose of such a design is that even if the locking block 425 extends out when the first sealing ring 3 is not in contact with the second sealing ring 4, it can be squeezed back into the connecting hole 424 by the lower end surface of the first sealing ring 3.

[0037] The pressure - locked component 42 includes three working modes, namely the steady - flow mode, the locked mode, and the return mode. In the steady - flow mode, the flow of the fluid in the blowout preventer body 1 is not blocked. The pressure fluctuation received by the pressure - receiving block 422 is small, and the upward movement amplitude is small, so it cannot squeeze the locking block 425 to extend. In the locked mode, when the overflow detection instrument detects an overflow, the driving cylinder 53 drives the driving ring 52 to move downward, so that the first sealing ring 3 moves axially downward. During this process, since the fluid movement channel is not completely cut off, even if the volume of the fluid movement channel decreases, the pressure fluctuation in the blowout preventer body 1 is within the normal fluctuation range and cannot push the locking block 425 to extend completely. When the first sealing ring 3 is stuck in the second sealing ring 4 to form a concave - convex fit and seal, the limiting hole 31 also moves to a position opposite to the connecting hole 424. The space between the blowout preventer body 1 and the lower end of the second sealing ring 4 is sealed. At this time, the liquid pressure in the blowout preventer body 1 increases rapidly, and the pressure received by the pressure - receiving block 422 also increases rapidly. The pressure - receiving block 422 then moves inward and pushes the locking block 425 to extend outward. At the same time, the limiting spring 423 and the connecting spring 426 are compressed, and the locking block 425 continues to move and completely extends and is stuck in the limiting hole 31. In this way, as long as the overflow exists, the liquid pressure in the blowout preventer body 1 is maintained at a high position, and the locking block 425 can be kept stuck in the limiting hole 31 all the time. According to the size of the liquid pressure in the blowout preventer body 1, the connection between the first sealing ring 3 and the second sealing ring 4 is locked, avoiding the adverse effect of excessive overflow pressure on the driving cylinder 53. Moreover, as long as there is an overflow, the first sealing ring 3 and the second sealing ring 4 are always in a locked state, and there is no need to use the driving cylinder 53 to limit the position of the first sealing ring 3. In the return mode, when the overflow detection instrument detects the stop of the overflow (or the overflow is diverted by other means), the pressure in the blowout preventer body 1 decreases rapidly. At this time, under the elastic action of the limiting spring 423 and the connecting spring 426, the locking block 425 and the pressure - receiving block 422 return, and the driving cylinder 53 can drive the first sealing ring 3 to move axially and return again. To sum up, when the overflow is blocked, according to the size of the liquid pressure in the blowout preventer body 1, the relative position between the first sealing ring 3 and the second sealing ring 4 is passively locked by the pressure - locked component 42, avoiding a heavy load on the driving cylinder 53. Moreover, when the overflow volume decreases, the liquid pressure in the blowout preventer body 1 decreases, and the locking block 425 and the pressure - receiving block 422 automatically return, so that the driving cylinder 53 can continue to control the movement of the first sealing ring 3, and the situation where the first sealing ring 3 and the second sealing ring 4 are completely stuck and subsequent work cannot be carried out can be avoided.

[0038] Furthermore, obviously, in actual work, there will be a situation where the overflow volume is too large. When the overflow volume is too large and the upward push damages the first sealing ring 3 or the locking block 425, the first sealing ring 3 will quickly push upward to give an instantaneous reverse pressure to the driving cylinder 53, which is likely to cause damage to the driving cylinder 53. Therefore, the present embodiment provides a further solution, including a disconnecting limit assembly 43. The disconnecting limit assembly includes a break opening 431 formed in the locking block 425. The break opening 431 is preferably a concave arc structure. The break opening 431 is used to define the disconnecting position of the locking block 425. A connecting rod 432 is fixedly provided at the upper end of the pressure receiving block 422. A relief hole 433 is formed in the connecting rod 432. The relief hole 433 penetrates through the connecting rod 432. An elastic limit rod 434 is installed on the inner wall of the blowout preventer body 1. The elastic limit rod 434 is preferably a telescopic elastic rod. The elastic limit rod 434 and the relief hole 433 are arranged in corresponding cooperation. In the initial state, the elastic limit rod 434 is in a compressed state, and the movable end of the elastic limit rod 434 is pressed against the upper end of the connecting rod 432. When the elastic limit rod 434 is fully extended, its movable end can extend below the first sealing ring 3. When the first sealing ring 3 and the second sealing ring 4 are gradually locked, the pressure receiving block 422 will move upward. At this time, the connecting rod 432 also moves upward accordingly, and the movable end of the elastic limit rod 434 slides relatively on the connecting rod 432. When the first sealing ring 3 and the second sealing ring 4 are fully locked, the relief hole 433 contacts the movable end of the elastic limit rod 434. Under the elastic action of the elastic limit rod 434, the movable end of the elastic limit rod 434 extends out of the relief hole 433 and extends above the first sealing ring 3. When the overflow volume is too large and the locking block 425 cannot lock the first sealing ring 3 and the second sealing ring 4, the locking block 425 disconnects from the break opening 431. At this time, the first sealing ring 3 moves upward a certain distance under the impact of huge pressure. However, at this time, the movable end of the elastic limit rod 434 is located above the first sealing ring 3. In this way, the first sealing ring 3 directly hits the movable end of the elastic limit rod 434 and is blocked. At this time, there is still a certain height difference between the first sealing ring 3 and the second sealing ring 4, and part of the fluid can be passed through to achieve pressure relief. In this way, through the above disconnecting limit assembly 43, when the overflow volume is too large, the first sealing ring 3 is protected and its rising distance is limited. First, the driving cylinder 53 is protected, and second, pressure relief is carried out inside the blowout preventer body 1.

[0039] More preferably, the upper end surface of the elastic limit rod 434 is an inclined surface, and the lower end surface is a horizontal surface. In this way, when the pressure receiving block 422 is reset, the movable end of the elastic limit rod 434 can be squeezed by the inner side wall of the relief hole 433, which is convenient for resetting the elastic limit rod 434 and the pressure receiving block 422.

[0040] Only certain exemplary embodiments of the present invention have been described above by way of illustration. Without doubt, for those of ordinary skill in the art, the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. An electric lifting anti-overflow mechanism, comprising a blowout preventer body, a drill pipe movably penetrating through the blowout preventer body, and a lifting assembly for moving the blowout preventer body, wherein the lifting assembly comprises a union connected to the wellhead and a lifting motor fixed on the union, and is characterized in that, A first sealing ring is slidably installed inside the blowout preventer body, and a second sealing ring is also fixed inside the blowout preventer body. An uneven sealing fit is formed between the first sealing ring and the second sealing ring. The first sealing ring is sleeved on the drill string, and a driving assembly is further included for driving the first sealing ring to move axially. When overflow is detected, the first sealing ring is driven by the driving assembly to move axially and snap into the second sealing ring to form a seal.

2. The electric lifting anti-overflow mechanism according to claim 1, wherein, In the initial state, there is a certain distance between the first sealing ring and the second sealing ring.

3. The electric lifting anti-overflow mechanism according to claim 1, characterized in that, A circular hole is formed inside the second sealing ring, and the circular hole is used for fluid passage. The shape of the side wall of the circular hole is the same as that of the side wall of the first sealing ring, and the diameter of the circular hole is larger than the diameter of the drill string.

4. The electric lifting anti-overflow mechanism according to claim 3, characterized in that, The side wall of the circular hole is a stepped structure, and the side wall of the first sealing ring is also a stepped structure.

5. The electric lifting anti-overflow mechanism according to claim 1, characterized in that, The blowout preventer body is of a tower-shaped structure as a whole. The blowout preventer body includes a first cylinder and a second cylinder connected to each other. The first cylinder is located above the second cylinder, and the diameter of the first cylinder is smaller than that of the second cylinder. The first sealing ring is slidably arranged inside the first cylinder.

6. The electric lifting anti-overflow mechanism according to claim 5, characterized in that, The driving assembly includes two connecting shafts slidably penetrating through the upper end of the first cylinder. A driving ring is connected between the two connecting shafts. The central axis of the driving ring coincides with the central axis of the first cylinder. Two oppositely arranged driving cylinders are installed at the upper end of the first cylinder, and the movable ends of the driving cylinders are connected to the driving ring.

7. The electric lifting anti-overflow mechanism according to claim 1, characterized in that, A dynamic sealing assembly is arranged on the inner side wall of the first sealing ring, and the first sealing ring contacts the drill string through the dynamic sealing assembly.

8. The electric lifting anti-overflow mechanism according to claim 7, characterized in that, The dynamic sealing assembly includes an annular groove formed on the inner wall of the first sealing ring. An annular mounting member is rotatably installed in the annular groove, and a sealing ring is movably sleeved inside the annular mounting member.

9. The electric lifting anti-overflow mechanism according to claim 8, characterized in that, The cross section of the sealing ring is circular.

10. The electric lifting anti-overflow mechanism according to claim 6, characterized in that, A spring rod is further connected between the connecting shaft and the driving ring.

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