An integrated device for separating and pressurizing multiphase flow at an oil and gas wellhead

Abstract

This invention relates to the field of oil well technology, specifically to an integrated multiphase flow separation and pressurization device for oil and gas wellheads. It includes a main casing and a multiphase flow inlet located on the side of the main casing. The main casing contains a bushing assembly and a barrier assembly. The bushing assembly is removably inserted into the main channel pipe of the main casing. The bushing assembly has a fluid monitoring channel along its axial direction. The barrier assembly is located directly below the bushing assembly. Through the displacement coordination between the bushing assembly and the barrier assembly, the barrier assembly can be driven to intervene in the flow channel to block or open the multiphase flow. This directly converts the displacement of the bushing assembly into an in-situ isolation action, thereby blocking the continuous pressure delivery of high-pressure formation fluid to the bushing assembly, facilitating convenient replacement of the bushing assembly in the future.

Description

Technical Field

[0001] This invention relates to the field of oil well technology, specifically to an integrated multiphase flow separation and pressurization device for oil and gas wellheads. Background Technology

[0002] In oil and gas resource development, the integrated multiphase flow separation and pressurization device at the wellhead is mainly used to solve the problems of pressure drop along the well and excessive back pressure at the wellhead caused by long-distance mixed transportation. Existing solutions typically connect a multiphase flow desander module in series with the booster pump, utilizing tangential centrifugal kinetic energy to strip solid particles and protect subsequent booster equipment from damage. However, in practical applications, severe wear caused by solid particles in the multiphase flow within the flow channel is a common problem. To address scouring damage, a common solution is to install high-hardness, wear-resistant bushings such as tungsten carbide or cobalt-based alloys inside the desander to resist the impact and cutting of solid particles in the fluid. When this equipment is used in low-pressure gas well environments during the later stages of production, characterized by high water content and high concentrations of formation particles and fracturing proppant, the existing equipment structure lacks an online quick-change mechanism. After key components wear and fail, the entire subsea system must be shut down and retrieved for repair. Once a critical component is worn through, on-site replacement is not possible, necessitating the shutdown of the entire system and retrieval for maintenance. This lack of a local quick-change mechanism leads to system maintenance paralysis, significantly increasing the economic risk of subsequent equipment operation and maintenance.

[0003] To address this, an integrated multiphase flow separation and pressurization device for oil and gas wellheads is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated multiphase flow separation and pressurization device for oil and gas wellheads. By using a removable double-layer bushing assembly and a bottom magnetic follow-up barrier assembly, the problem of the core separation component being susceptible to strong erosion and requiring well shutdown and pressure relief for replacement is transformed into a purely mechanical linkage problem of pre-sacrificial buffering and automatic cut-off during insertion and removal. This prevents the core separation unit from direct damage, thus significantly extending its service life. At the same time, it can achieve the effect of spontaneously constructing a high-pressure sealed isolation zone at the moment of material removal. Combined with the time-sequential pressure relief of the top drain port, it can achieve pressurized quick replacement without well control and with zero surging.

[0005] To achieve the above objectives, the present invention provides the following technical solution: An integrated multiphase flow separation and pressurization device for oil and gas wellheads includes a main shell and a multiphase flow inlet located on the side of the main shell. The main shell is provided with a bushing assembly and a barrier assembly. The bushing assembly is removably inserted into the main channel pipe of the main shell to receive and rectify turbulent multiphase flow to weaken the destructive force of the fluid and guide the fluid to the peripheral separation unit. The bushing assembly is provided with a fluid monitoring channel along the axial direction to passively conduct internal fluid when the pipe wall is worn down by fluid to a preset physical safety limit, thereby triggering an extreme wear warning. The barrier component is located directly below the bushing component. The bushing component and the barrier component are displaced together, which can drive the barrier component to enter the flow channel to block or open the multiphase flow. In turn, the displacement of the bushing component is directly converted into an in-situ isolation action. An independent isolation cavity is formed in the main channel pipe to accommodate the bushing component, so as to block the continuous pressure delivery of high-pressure fluid from the formation to the bushing component. The device has a pluggable bushing assembly and a follow-up barrier assembly coaxially installed inside the main housing. The bushing assembly is used to buffer and rectify multiphase flow, guide phase separation, and passively conduct fluid to trigger an early warning when the pipe wall wears to its limit using an axially arranged monitoring channel. At the same time, through the mechanical displacement linkage of the two, the bottom barrier assembly is directly driven to intervene and block the multiphase flow inlet when the bushing is axially pulled out for maintenance, thus constructing an independent isolation cavity area in situ inside the equipment to meet the subsequent online quick replacement requirements of the bushing assembly.

[0006] Preferably, the bushing assembly adopts a double-layer composite anti-erosion structure, including an outer rigid pressure-bearing frame for bearing the high pressure of the system, and an inner elastic damping layer nested and fixed inside the outer rigid pressure-bearing frame; the inner elastic damping layer is used to directly contact the multiphase flow introduced by the multiphase flow inlet to absorb the impact kinetic energy of solid particles.

[0007] Preferably, the fluid monitoring channel consists of a plurality of blind holes extending axially along the tube wall of the bushing assembly; the multiple blind holes are spaced apart circumferentially along the bushing assembly, and each blind hole is not interconnected; the blind holes are opened within the outer rigid pressure-bearing frame, and the preset physical safety limit is the interface between the outer rigid pressure-bearing frame and the inner elastic damping layer; the inner blind end of the blind hole extends inward and terminates at the interface, without penetrating the inner elastic damping layer; the port of the blind hole is aligned with the built-in passive pressure RFID tag, which is located at the top of the bushing assembly; a loop antenna is completely sealed and embedded at the point where the inner wall of the main channel tube is flush with the position of the inserted bushing chip; a micro-deformable metal diaphragm is sealed between the top port of the blind hole and the passive pressure RFID tag; The system employs unconnected axial blind holes arranged within the outer rigid pressure-bearing frame, ending at the interface of the double-layer structure, with the inner elastic damping layer serving as a sacrificial defense. During the normal wear-out period of the damping layer, the system remains sealed. If localized erosion causes the inner layer to wear through and expose the interface, high-pressure multiphase flow will directionally intrude into the blind holes in that area, triggering a physical alarm. This mechanism avoids the potential for electronic sensor failure in deep-sea conditions, providing accurate early warning before damage to the core pressure-bearing frame. Simultaneously, the unconnected blind hole structure prevents high-pressure cross-flow within the pipe wall, providing a precise opportunity for in-situ underwater maintenance while maintaining the overall pressure-bearing strength of the device.

[0008] Preferably, the inner elastic damping layer at the bottom of the bushing assembly is provided with a flow-regulating and flow-slowing structure; the flow-slowing structure includes a plurality of wedge-shaped ribs distributed circumferentially along the inner wall, the flow-facing surface of the wedge-shaped ribs is a teardrop-shaped streamlined curved surface, so as to sort out and smooth the introduced turbulent multiphase flow; and the wedge-shaped ribs are integrally formed from the elastic consumable material of the inner elastic damping layer, so as to directly absorb the impact kinetic energy of the fluid while guiding the flow. The teardrop-shaped streamlined wedge ribs distributed circumferentially on the inner wall can effectively sort out and transform the turbulent multiphase flow from the side surge into a smooth and orderly flow state, eliminating destructive vortices and cavitation at the source, and providing an ideal hydrodynamic basis for subsequent swirl separation. At the same time, relying on the material characteristics of the integrally molded elastic consumable, these wedge ribs act as buffers to directly absorb and dissipate the initial impact kinetic energy of the high-speed sand-containing fluid, achieving anti-erosion protection of the flow field.

[0009] Preferably, the barrier block in the barrier assembly is disposed in the main housing cavity below the multiphase flow inlet, and the bottom of the barrier block is supported by a compression spring vertically arranged in the main housing cavity; a first magnetic pole is provided at the top of the barrier block, and a second magnetic pole is provided at the bottom of the bushing assembly; the first magnetic pole and the second magnetic pole are configured as permanent magnets with the same polarity; both the first magnetic pole and the second magnetic pole are made of high-temperature resistant permanent magnet material, and the first magnetic pole and the second magnetic pole are respectively completely sealed and encapsulated in an isolation shell made of non-magnetic wear-resistant alloy, so as to physically isolate the permanent magnet from the multiphase fluid; By introducing a dynamic mechanical balance between the repulsive magnetic force of like poles and the bottom compression spring, the insertion and removal displacement of the bushing assembly is transformed into the mechanical contactless opening and closing of the bottom barrier block. This avoids the weakness of traditional physical transmission rods, which are prone to jamming and failure in harsh fluids. At the same time, the fully sealed encapsulation structure, which combines high-temperature resistant magnetic materials and non-magnetic wear-resistant alloys, not only effectively prevents irreversible demagnetization of the magnet in high-temperature well fluids, but also physically isolates the magnetic adsorption and corrosion erosion of iron filings and impurities in multiphase flow. This provides a stable and jam-proof bottom layer of safety for the pressure-free quick-change of the underwater separation system throughout its lifespan. In addition, the movement of the barrier block effectively cleans the sand and gravel adhering to the main shell.

[0010] Preferably, the bushing assembly is the central hub for rectifying and transitioning the flow field inside the entire main housing, and its pipe wall side is provided with several radial diversion side holes, which are respectively connected to the liquid inlet of the corresponding main channel pipe on the periphery. A cutting component is also provided inside the main channel pipe at the liquid inlet; the cutting component includes a first magnet block embedded in the outer wall of the bushing assembly and a second magnet block provided in the groove of the main channel pipe; a first reset spring is provided inside the groove, and the first reset spring is fixedly connected to the second magnet block; the axial displacement of the bushing assembly is synchronously converted into a spontaneous cutting action of the lateral branch flow channel.

[0011] Preferably, the top of the bushing assembly is coaxially connected to a locking cylinder with external threads via a rotary joint, and the inner wall of the main channel tube is provided with a matching internal thread groove; the locking cylinder is configured to be freely screwed into the internal thread groove in situ to apply a downward axial locking force to the bushing assembly below without generating circumferential torque interference; the top of the locking cylinder is provided with a lug for screwing the locking cylinder; the top of the bushing assembly is provided with a drain port; The external threaded locking cylinder provides a strong downward axial clamping force to resist the upward thrust of high-pressure fluid in the deep sea. At the same time, the rotary joint isolates the circumferential torque during screwing, ensuring that the lower bushing is compressed but does not rotate, thus protecting the precision positioning and sealing mechanism at the bottom from wear. In addition, the top lugs not only provide an easy-to-grip point for the underwater robot to reduce the difficulty of blind operation, but also, during later maintenance and disassembly, utilize the mechanical amplification effect of the reverse thread to powerfully break through deep-sea corrosion cold welding and mud and sand blockage, comprehensively ensuring the success rate of in-situ online insertion and removal operations in the deep sea. The top drain port precisely solves the pain points of environmental protection and flow field balance in deep-sea maintenance. After the bottom barrier component cuts off the main channel pipe, it allows the external suction pump to safely extract the residual multiphase flow in the bushing to prevent marine pollution during extraction. When the new part is assembled in place, the accumulated seawater inside is extracted in the reverse direction and the multiphase flow is reinjected.

[0012] Preferably, a pressure-bearing cap assembly is detachably and sealingly connected to the top of the main housing; the pressure-bearing cap assembly includes a top cap and a support column, the internal thread groove of the top cap matches the external thread groove of the top of the main housing, and the support column is fixedly connected to the top cap, forming an abutment against the bushing assembly; The combination of the main channel pipe and the pressure cap assembly not only provides the underwater robot with a vertical insertion and removal space without interference, but also utilizes the rigid contact between the threaded top cap and the support column to construct a secondary axial compression and high-pressure sealing defense line for the bushing assembly.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention utilizes the cooperation between the bushing assembly, the bottom blocking assembly, and the lateral cutting assembly to spontaneously construct a physically isolated pressureless zone when the damaged bushing is pulled out. Combined with the sequential fluid replacement of the top drain port, it eliminates the complicated processes of well control, pressure relief, and whole-machine retrieval in traditional operations, transforming high-risk pressurized operations into purely mechanical displacement cooperation, and achieving in-situ leak-free replacement under non-stop well conditions.

[0014] 2. This invention uses the inner elastic damping layer as a sacrificial component, and pre-sets non-interconnected axial blind holes at the junction of the rigid skeleton. When the inner layer is partially worn through, high-pressure fluid directionally enters the blind holes and triggers the top passive RFID tag, which reads the alarm signal remotely via an antenna. This structure not only prevents large-area high-pressure flow inside the pipe wall, but also avoids the risk of underwater live plugging and unplugging through physical conductivity and passive induction, providing precise and accurate maintenance opportunities.

[0015] 3. This invention uses a double-layer composite structure and teardrop-shaped wedge ribs to absorb the impact energy of multiphase flow in advance and complete rectification, effectively suppressing cavitation to protect the downstream separation core. At the same time, it uses the same-pole magnetic repulsion force and spring to build dynamic mechanical balance, combined with wear-resistant alloy sealed packaging, to eliminate the hard friction and jamming hazards of traditional mechanical connecting rods in sand-containing well fluids, significantly extending the overall life of the equipment.

[0016] 4. The present invention ensures that the lower bushing assembly only bears pure axial clamping force and does not rotate circumferentially through the cooperation between the locking cylinder, the lug and the bushing assembly. At the same time, the bushing assembly is further resisted by the pressure cap assembly to prevent the high pressure fluid from generating a continuous upward thrust on the internal bushing assembly. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the integrated multiphase flow separation and pressurization device for oil and gas wellheads according to the present invention; Figure 2 This is a schematic diagram of the front view of the integrated multiphase flow separation and pressurization device for oil and gas wellheads according to the present invention; Figure 3 For the present invention Figure 2 Sectional view of AA; Figure 4 For the present invention Figure 2 BB section view; Figure 5 This is a top view of the integrated multiphase flow separation and pressurization device for oil and gas wellheads according to the present invention. Figure 6 For the present invention Figure 5 CC section view; Figure 7 For the present invention Figure 6 Enlarged view of a section at point D; Figure 8For the present invention Figure 6 Enlarged view of a section at point E in the middle; Figure 9 This is a schematic diagram of the bushing assembly structure of the present invention; Figure 10 This is a schematic diagram of the main channel pipe and bushing assembly of the present invention; Figure 11 This is a bottom view of the main channel pipe and bushing assembly of the present invention; Figure 12 This is a schematic diagram of the passive pressure radio frequency tag of the present invention.

[0018] In the diagram: 1. Main housing; 2. Main channel pipe; 3. Multiphase flow inlet; 4. Bushing assembly; 41. Outer rigid pressure-bearing frame; 42. Inner elastic damping layer; 43. Blind hole; 44. Wedge rib; 45. Radial diversion side hole; 46. Locking cylinder; 47. Hanging lug; 48. Drain port; 5. Barrier assembly; 51. Barrier block; 52. Compression spring; 53. First magnetic pole; 54. Second magnetic pole; 6. Liquid inlet; 7. Cut-off assembly; 71. First magnet block; 72. Second magnet block; 73. First reset spring; 74. Groove; 8. Top cap; 9. Support column; 11. Passive pressure RFID tag; 12. Metal diaphragm; 13. Loop antenna. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] Please see Figures 1 to 12 This invention provides an integrated multiphase flow separation and pressurization device for oil and gas wellheads, the technical solution of which is as follows: An integrated multiphase flow separation and pressurization device for oil and gas wellheads includes a main shell 1 and a multiphase flow inlet 3 located on the side of the main shell 1. The main shell is provided with a bushing assembly 4 and a barrier assembly 5. The bushing assembly 4 is removably inserted into the main channel pipe 2 of the main shell 1 to receive and rectify turbulent multiphase flow to weaken the destructive force of the fluid and guide the fluid to the peripheral separation unit. The bushing assembly 4 is provided with a fluid monitoring channel along the axial direction to passively conduct the internal fluid when the pipe wall is worn down by the fluid to a preset physical safety limit, so as to trigger an extreme wear warning. The barrier component 5 is located directly below the bushing component 4. The bushing component 4 and the barrier component 5 are displaced and coordinated, which can drive the barrier component 5 to enter the flow channel to block or open the multiphase flow. In turn, the displacement of the bushing component 4 is directly converted into an in-situ isolation action. An independent isolation cavity for accommodating the bushing component 4 is formed in the main channel pipe 2 to block the continuous pressure delivery of high-pressure fluid from the formation to the bushing component 4. By coordinating the spatial displacement of bushing assembly 4 and barrier assembly 5 under different working conditions, the pressurized operation is transformed into a mechanical action, and its complete working cycle is as follows: Under normal separation and pressurization operation conditions, the bushing assembly 4 is coaxially inserted into the main channel pipe 2 of the main housing 1. At this time, the bottom end of the bushing assembly 4 applies a downward axial force to the barrier assembly 5 directly below, forcing the barrier assembly 5 to overcome its bottom pressure, retreat downward and hide in the cavity of the main housing 1 below the multiphase flow inlet 3, thereby completely opening the lateral multiphase flow inlet 3. At this time, the high-pressure, turbulent multiphase flow mixed with fracturing sand that surges in from the wellhead will first impact and enter the interior of the bushing assembly 4. As the pre-rectification transition center of the entire flow field, the bushing assembly 4 first receives and absorbs the initial impact kinetic energy of the fluid, and gently sorts the turbulent jet. Subsequently, the rectified fluid is precisely and tangentially guided through its pipe wall to each swirling separation unit arranged in the outer array, thereby forming a stable high-speed centrifugal vortex to complete the three-phase separation of gas, liquid and solid. In this stage, the bushing assembly 4 acts as a sacrificial component to protect the subsequent swirling core. When the bushing assembly 4 is partially worn through, triggering a physical warning and requiring underwater replacement, the underwater robot unlocks the top lock and pulls the damaged old bushing assembly 4 upwards axially. At the instant the bushing assembly 4 is pulled upwards out of the main channel pipe 2, its downward pressure on the lower blocking assembly 5 is simultaneously released. At this time, the pressure at the bottom of the blocking assembly 5 is released instantly, driving the blocking assembly 5 to slide upwards along the main shell 1 and precisely stop at the high point of the multiphase flow inlet 3, blocking and cutting off the side surge of high-pressure multiphase flow and the bottom of the main channel pipe 2. This spontaneous cut-off, accompanied by the insertion and removal action, utilizes the bottom blocking block 51 to physically block the high-pressure fluid in the formation, thereby instantly constructing a temporary sealed isolation zone that is completely physically isolated from the deep-sea high-pressure well flow within the original bushing installation space (upper half of the main channel pipe 2) above the blocking component 5 (at this time, there is residual high-pressure produced fluid in the zone). Subsequently, the underwater robot, through the pre-connected drain port 48 located at the top of the bushing component 4, safely releases and dissipates the residual high pressure in the isolation zone and transforms it into a relatively low-pressure isolation zone. Within this pressure-free dead zone, the underwater robot can calmly and completely pull out the old bushing and reinsert the new bushing component 4 into the main channel pipe 2. When the new bushing component 4 is pressed down again, it forces the blocking component 5 back into the cavity of the main shell 1, and the multiphase flow inlet 3 instantly regains its conductivity, allowing the entire system to seamlessly resume continuous production.

[0021] As one embodiment of the present invention, refer to Figure 3 , 4 6, 8 and 12, the bushing assembly 4 adopts a double-layer composite anti-erosion structure, including an outer rigid pressure-bearing frame 41 for bearing the high pressure of the system, and an inner elastic damping layer 42 nested and fixed inside the outer rigid pressure-bearing frame 41; the inner elastic damping layer 42 is used to directly contact the multiphase flow introduced by the multiphase flow inlet 3 to absorb the impact kinetic energy of solid particles. The fluid monitoring channel consists of several blind holes 43 extending axially along the wall of the bushing assembly 4; the blind holes 43 are spaced apart circumferentially along the bushing assembly 4, and are not interconnected; the blind holes 43 are located within the outer rigid pressure-bearing frame 41, and the preset physical safety limit is the interface between the outer rigid pressure-bearing frame 41 and the inner elastic damping layer 42; the blind end of the blind hole 43 extends inward and terminates at the interface, without penetrating the inner elastic damping layer 42; the port of the blind hole 43 is aligned with the built-in passive pressure RFID tag 11, which is located at the top of the bushing assembly 4; a loop antenna 13 is completely sealed and embedded at the point where the inner wall of the main channel tube 2 is flush with the inserted bushing chip; a micro-deformable metal diaphragm 12 is sealed between the top port of the blind hole 43 and the passive pressure RFID tag 11. The inner elastic damping layer 42 at the bottom of the bushing assembly 4 is provided with a flow-regulating and flow-slowing structure. The flow-slowing structure includes a number of wedge-shaped ribs 44 distributed circumferentially along the inner wall. The flow-facing surface of the wedge-shaped ribs 44 is a teardrop-shaped streamlined surface to smooth and soften the introduced turbulent multiphase flow. The wedge-shaped ribs 44 are integrally formed from the elastic material of the inner elastic damping layer 42 to directly absorb the impact kinetic energy of the fluid while guiding the flow. The number of wedge-shaped ribs 44 is preferably 3-6, and they are centrally symmetrically distributed. The aspect ratio of their teardrop-shaped streamlined surface is designed to be between 2:1 and 4:1, and their flow-facing surface has a flow-guiding chamfer of 15°-30° relative to the radial plane of the main shell. Through a double-layer composite anti-scouring structure, fluid monitoring blind holes 43, and an electromechanical wireless communication scheme, multi-dimensional physical linkage is achieved. When high-pressure turbulent multiphase flow mixed with solid particles surges in from the bottom, the fluid will first impact the inner elastic damping layer 42 and its bottom integrally formed teardrop-shaped wedge ribs 44. These wedge ribs 44 use their streamlined curved surfaces to transform the side-flowing fluid into a smooth and orderly flow state, and rely on the elastic material to directly absorb the initial impact kinetic energy of the solid particles, thereby comprehensively protecting the outer rigid frame used to bear the high pressure of the system from direct scouring damage. During the long-term operation and wear of the equipment, the circumferentially distributed and non-interconnected axial blind holes 43 inside the outer rigid frame serve as passive monitoring channels, lurking at the interface of the double-layer bonding. They maintain physical sealing during the normal wear of the inner damping layer. Once the local pipe wall is subjected to extreme scouring, causing the inner layer to be worn through and the interface to be exposed, the high-pressure multiphase flow will instantly and directionally invade the blind holes in that specific area. 43 rises upward along the axial channel, and the fluid pressure acts on the metal diaphragm 12, causing it to deform upward mechanically. This deformation directly pushes the miniature elastic capacitor plate inside the passive pressure RFID tag 11, changing the capacitance parameters of the resonant circuit, which in turn causes a sudden change in the reflection frequency of the RFID tag. At this time, the ring radio antenna, which is completely sealed and embedded in the corresponding position on the inner wall of the main channel tube 2, crosses the physical barrier and captures the radio frequency signal of the tag's abnormal movement in real time. This instantly transforms the purely mechanical fluid conduction into a passive electronic warning signal. By using the inner damping layer as a pre-sacrificial defense line, it not only avoids the weaknesses of live plugging and unplugging in the deep sea environment and the easy damage and failure of conventional electronic sensors, but also effectively prevents high-pressure crossflow inside the tube wall by the unconnected blind holes 43. Under the premise of ensuring that the outer rigid skeleton is not substantially damaged and maintaining the overall pressure bearing strength of the device, it provides a safe and accurate maintenance opportunity for the in-situ quick replacement of the underwater robot.

[0022] As one embodiment of the present invention, refer to Figure 3 and 6The barrier block 51 in the barrier assembly 5 is disposed in the cavity of the main housing 1 below the multiphase flow inlet 3. The bottom of the barrier block 51 is supported by a compression spring 52 arranged vertically in the cavity of the main housing 1. The top of the barrier block 51 is provided with a first magnetic pole 53, and the bottom of the bushing assembly 4 is provided with a second magnetic pole 54. The first magnetic pole 53 and the second magnetic pole 54 are configured as permanent magnets with the same polarity. The first magnetic pole 53 and the second magnetic pole 54 are both made of high-temperature resistant permanent magnet material, and the first magnetic pole 53 and the second magnetic pole 54 are completely sealed and encapsulated in an isolation shell made of non-magnetic wear-resistant alloy, so as to physically isolate the permanent magnet from the multiphase fluid. The displacement of the baffle block 51 is achieved by a precise dynamic mechanical balance between the repulsive magnetic force and the bottom compression spring 52. During this linkage process, strict physical limits must be imposed on the magnetic force and spring force: when the bushing assembly 4 is inserted downwards, its bottom second magnetic pole 54 approaches the top first magnetic pole 53 of the baffle block 51. At this point, the minimum working magnetic repulsion force is greater than the maximum resistance of the compression spring 52, the weight of the baffle block 51 (which is a hollow structure), and the sum of the fluid's upward resistance. The magnetic repulsion force, spring force, and fluid pressure are matched according to the predetermined wellhead pressure level, thereby using a powerful, non-hard-contact magnetic repulsion force to force the baffle block 51 downwards and compress the spring 52, concealing it within the blind end cavity to fully open the multiphase flow inlet 3. Conversely, when the underwater machine... When the robot pulls out the bushing assembly 4 upwards, the distance between the two magnetic poles increases, causing the magnetic repulsion to decrease exponentially or even disappear. At this time, the release force of the compression spring 52 is sufficient to overcome the lateral friction and jamming force of the high-pressure side-flowing fluid and the gravity of the blocking block 51 itself. Relying on the spring potential energy, the blocking block 51 is pushed upwards to the bottom of the multiphase flow inlet 3 and the main channel pipe 2 to achieve physical cut-off. Through the mechanical extreme value matching and the fully sealed encapsulation structure of the non-magnetic wear-resistant alloy, not only is the risk of hard friction and jamming that is easy to occur in mud and sand in traditional mechanical connecting rods eliminated, but also the high-temperature demagnetization and iron filings adsorption effect of well fluid on permanent magnets is shielded from the physical source. Thus, the mechanical insertion and removal action of the bushing assembly 4 is transformed into a bottom-level pressureless isolation follow-up defense line that is not affected by fluid contamination and prevents jamming within the predetermined maintenance cycle.

[0023] As one embodiment of the present invention, refer to Figure 3 , 4 6, 7, 9 and 10, the bushing assembly 4 is the central hub for rectifying and transitioning the flow field inside the entire main shell 1, and its pipe wall side is provided with several radial diversion side holes 45, which are respectively connected to the liquid inlet 6 of the corresponding outer main channel pipe 2. A cutting component 7 is also provided inside the main channel pipe 2 at the liquid inlet 6; the cutting component 7 includes a first magnet 71 embedded in the outer wall of the bushing assembly 4 and a second magnet 72 disposed in the groove 74 of the main channel pipe 2; a first return spring 73 is disposed inside the groove 74 and is fixedly connected to the second magnet 72; the axial displacement of the bushing assembly 4 is synchronously converted into a spontaneous cutting action of the lateral branch flow channel; the swirling separation unit inside the main housing 1 is a swirling cylinder arranged in an array around the periphery of the bushing assembly 4; the radial diversion side hole 45 and the liquid inlet 6 are respectively connected to the inlet of each corresponding swirling cylinder on the periphery, and the multiphase flow enters the swirling cylinder tangentially through the inlet to form a high-speed centrifugal vortex; Through the precise spatial coordination of the radial diversion structure and the cutting component 7, under normal separation production conditions, the bushing component 4, which serves as the flow field rectification transition center, is inserted downwards into place. At this time, the first magnet 71 embedded on its outer wall surface is precisely aligned with the second magnet 72 in the groove 74 of the outer vortex separation unit docking wall at the same horizontal height. The strong magnetic force generated between the two magnets in an instant directly overcomes the pre-tightening force of the first reset spring 73 inside the groove 74, driving the second magnet 72, which serves as the valve plate, to retract into the groove 74, thereby fully opening the liquid inlet 6. This allows the multiphase flow in the main channel pipe 2, which has undergone preliminary buffering, to smoothly enter the vortex cylinder through the radial diversion side hole 45, the liquid inlet 6, and the inlet tangentially, thereby forming a stable high-speed centrifugal vortex based on the physical structure to complete the efficient separation of the gas, liquid, and solid phases. When the equipment enters the pressurized quick-change mode, as the underwater robot pulls out the bushing assembly 4 upward, the first magnet 71 moves upward, causing the second magnet 72 to move upward. When the first magnet 71 and the second magnet 72 separate, the magnetic force rapidly decays and disappears. The elastic force generated by the first reset spring 73 inside the groove 74 continues to support the second magnet 72 to block the liquid inlet 6, and also blocks the inlets of each vortex separation unit. The single axial pull-out displacement of the bushing assembly 4 is instantly and synchronously transformed into the spontaneous physical cut-off action of all lateral branch channels, cutting off the fluid connection between each vortex and the bushing assembly 4. From the physical source, the inflow of high-pressure fluid from the outside into the vortex is prevented. Furthermore, it forms a three-dimensional closed pipeline with the bottom barrier assembly 5, further consolidating the pressureless isolation dead zone in the main channel, and providing lateral fluid isolation guarantee for the safe pressurized quick-change of the entire equipment. The main channel pipe 2 is a hexagon with a partially concave surface located between the cyclone tube and the bushing assembly 4, which enables communication between the bushing assembly 4 and the cyclone tube. Without the main channel pipe 2, relying solely on the tangency between the cyclone tube and the bushing assembly 4 would result in a gap between the radial diversion side hole 45 and the liquid inlet 6, leading to leakage of the multiphase liquid. The specific operation of the cyclone tube and the discharge of materials are existing technologies.

[0024] As one embodiment of the present invention, refer to Figure 3 and 6 The top of the bushing assembly 4 is coaxially connected to a locking cylinder 46 with external threads via a rotary joint. The inner wall of the main channel pipe 2 is provided with a matching internal thread groove. The locking cylinder 46 is configured to be freely screwed into the internal thread groove in situ to apply a downward axial locking force to the bushing assembly 4 below without generating circumferential torque interference. The top of the locking cylinder 46 is provided with a lug 47 for screwing the locking cylinder 46. The top of the bushing assembly 4 is provided with a drain port 48. The top of the main housing 1 is detachably sealed with a pressure-bearing cap assembly. The pressure-bearing cap assembly includes a top cap 8 and a support column 9. The internal thread groove of the top cap 8 matches the external thread groove on the top of the main housing 1. The support column 9 is fixedly connected to the top cap 8, forming abutment against the bushing assembly 4. Through the coordinated operation of the mechanical anti-interference double clamping structure and the strict time-sequential fluid replacement operation of the top drain port 48, under normal production conditions, the pressure-bearing cap assembly connected to the top of the main shell 1 uses its internally fixed support column 9 to form a rigid contact with the top of the bushing assembly 4, constructing a secondary high-pressure sealing defense line. At the same time, the underwater robot grabs and screws the lug 47 on the top of the locking cylinder 46, driving the locking cylinder 46 with external threads to forcefully screw into the internal thread groove of the main channel. Since there is a rotary joint coaxially connected between the locking cylinder 46 and the bushing assembly 4, the huge circumferential torque generated when the locking cylinder 46 is screwed is physically isolated by the joint, and only the pure downward axial clamping force is transmitted to the bushing assembly 4 below, ensuring that the bushing assembly 4 is locked under pressure but does not rotate, thereby protecting the precision positioning mechanism at the bottom from friction damage. When entering the in-situ extraction and maintenance mode, the underwater robot first removes the top cap 8 and moves the locking cylinder 46 upward to generate axial displacement, causing the blocking block 51 and the second magnet block 72 to reset accordingly, physically locking the high pressure at the wellhead and the back pressure of the lateral vortex cylinder in the middle section of the main channel pipe 2; at this time, the upper cavity is in a transient high-pressure sealed state; the underwater robot's operating pipeline is connected to the drain port 48, and the pressure sensor integrated at the pipeline end monitors the gauge pressure inside the cavity; if the pressure does not rise within the preset observation time, it is determined that the bottom layer and the lateral magnetic follow-up seals are working properly and there is no high-pressure flow. After confirming that the seal is intact, the robot connects the drain port 48 to the external low-pressure liquid collection chamber. Utilizing the huge static pressure difference, the control valve at the drain port 48 is opened, allowing the residual high-pressure produced fluid in the chamber to spontaneously release energy into the low-pressure chamber. As the fluid is discharged, the residual static pressure in the chamber rapidly decays to atmospheric pressure in an exponential curve. When the pressure monitoring shows that the gauge pressure in the chamber is zero, the area is truly transformed into a safe, pressureless isolation dead zone. At this point, the robot can use a suction pump to remove the residual atmospheric pressure waste liquid and completely loosen the locking cylinder 46 to remove the old bushing. The entire quick replacement process achieves a completely non-surge-free maintenance closed loop by pre-dissipating the high-pressure fluid energy through the drain port 48, thus reducing the risk of fluid leakage. Correspondingly, in the assembly and production resumption process of inserting the new bushing assembly 4, when the new bushing assembly 4 has just been inserted into place, and the bottom of the main pipe is still closed, the radial diversion side hole 45 is blocked by the main channel pipe 2, and the peripheral liquid inlet 6 is still blocked, the underwater robot once again pumps out the seawater trapped inside the new bushing through the discharge port 48 in the reverse direction, and then re-injects the multiphase flow pumped out in the previous stage back into the bushing to achieve a seamless balance between pressure and medium. Finally, the underwater robot re-tightens the locking cylinder 46 and installs the pressure cap assembly to release the bottom blockage under pressure reset. This fluid replacement and anti-torque dual clamping mechanism based on a specific time sequence realizes a closed-loop maintenance system that reduces pollution, leakage and stabilizes the deep-sea system without stopping the well.

[0025] Working principle: Under normal production conditions, the pressure cap assembly and the locking cylinder 46 inside the main channel pipe 2 use a rotary joint to cut off the circumferential torque and apply a pure axial rigid downward pressure to lock the bushing assembly 4. At this time, the second magnetic pole 54 at the bottom of the bushing assembly 4 has an extreme magnetic repulsion force that is greater than the sum of the resistance of the bottom compression spring 52 and the fluid resistance. It forces the first magnetic pole 53 and the blocking block 51 downward into the cavity of the main housing 1 through the air, and completely opens the lateral multiphase flow inlet 3. At the same time, the first magnet block 71 on the outer wall of the bushing and the second magnet block 72 in the groove 74 are precisely aligned. The strong magnetic force overcomes the pre-tightening force of the first reset spring 73 and forces the second magnet block 72 back, thereby completely opening the liquid inlet 6 of the peripheral vortex separation unit. The high-pressure, sand-laden multiphase flow entering from the wellhead first impacts the bushing assembly 4. The inner elastic damping layer 42 and its integrally formed teardrop-shaped wedge rib 44 absorb the initial impact kinetic energy and smooth the turbulent jet. The rectified fluid then flows smoothly through the radial diversion side hole 45 via the main channel pipe 2 (which has a partially concave hexagonal structure on its outer wall to eliminate tangential gaps and prevent leakage) into the inverted conical vortex tube, forming a high-speed centrifugal vortex to achieve efficient gas-liquid-solid three-phase separation. During long-term operation, the inner damping layer, acting as a sacrificial defense, is continuously consumed. Once it wears through to the interface, the high-pressure fluid directionally invades the non-connected axial blind holes 43 within the rigid frame and... The upward surge, triggered by mechanical pressure, caused a sudden change in the state of the passive pressure RFID tag 11 at the top. This was captured in real time by the loop antenna 13 on the inner wall of the main channel pipe 2 and converted into an electronic early warning signal, providing a precise maintenance opportunity. When entering the in-situ pressurized quick-change condition, the underwater robot first removed the pressure cap assembly and loosened the locking cylinder 46 to initially pull the damaged bushing assembly 4 upward. With this single axial displacement, the equipment spontaneously completed a multi-dimensional cut-off linkage: the distance between the magnetic poles at both ends of the bottom increased, causing the magnetic repulsion force to decay rapidly. The bottom compression spring 52 instantly released energy, pushing the blocking block 51 upward to block the multiphase flow inlet 3 and the bottom of the main channel pipe 2. At the same time, the first magnet block 71 and the second magnet block 72 separated laterally, and the first reset... Spring 73 releases its elastic force, supporting the second magnet 72 to pop out and block the inlet 6 of the main channel pipe 2. Additionally, the radial diversion side hole 45 is physically shielded by the inner wall of the main channel pipe 2, thus instantly creating a transient, sealed high-pressure zone in the upper half of the main channel pipe 2, completely physically isolated from the deep-sea high pressure. Under this isolation, the underwater robot's external pipeline connection to the drain port 48 performs pressure testing. After confirming the effectiveness of the bottom and lateral sealing, the high-pressure produced fluid accumulated in the cavity is guided through the drain port 48 to the external low-pressure chamber for static pressure release and energy dissipation. Once the pressure inside the cavity returns to zero, forming a relatively low-pressure isolation zone, the residual fluid is pumped out using a suction pump, and the old bushing is completely removed by loosening, preventing high-pressure gushing and oil-bearing well fluid from entering the marine environment. The system prevents leakage and pollution. In the resumption of production after inserting a new bushing assembly 4, when the new bushing is just inserted and the bottom and side inlets 6 of the main pipeline and the radial diversion holes are still physically closed, the underwater robot once again pumps out the seawater trapped inside the new bushing through the discharge port 48. Then, it injects the multiphase flow pumped out in the previous stage back into the bushing to achieve a seamless balance between pressure and medium. Finally, the underwater robot tightens the locking cylinder 46 and installs the pressure cap assembly. The downward reset action overcomes the spring force to release the physical blockage at the bottom and sides. The multiphase flow inlet 3 and the inlet 6 are restored to conduction. The entire system can then seamlessly resume continuous production with reduced pollution and no pressure well.

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

Claims

1. An integrated multiphase flow separation and pressurization device for oil and gas wellheads, comprising a main shell (1) and a multiphase flow inlet (3) located on the side of the main shell (1) and connected to the oil and gas wellhead, characterized in that: The main shell is provided with a bushing assembly (4) and a barrier assembly (5). The bushing assembly (4) is removably inserted into the main channel pipe (2) of the main shell (1) to receive and rectify the sand-containing high-pressure produced fluid flowing in from the wellhead to weaken the destructive force of the fluid; and guide the fluid to the peripheral separation unit; the bushing assembly (4) is provided with a fluid monitoring channel along the axial direction to passively conduct the internal fluid when the pipe wall is worn down by the fluid to a preset physical safety limit, so as to trigger the ultimate wear warning. The barrier component (5) is located directly below the bushing component (4). The bushing component (4) and the barrier component (5) are displaced and cooperate, which can drive the barrier component (5) to enter the flow channel to block or open the multiphase flow, thereby directly converting the displacement of the bushing component (4) into an in-situ isolation action, and forming an independent isolation cavity for accommodating the bushing component (4) in the main channel pipe (2) to block the continuous pressure delivery of high-pressure fluid from the formation to the bushing component (4).

2. The integrated multiphase flow separation and pressurization device for oil and gas wellheads according to claim 1, characterized in that: The bushing assembly (4) adopts a double-layer composite anti-scouring structure, including an outer rigid pressure-bearing frame (41) for bearing the high pressure of the system, and an inner elastic damping layer (42) nested and fixed inside the outer rigid pressure-bearing frame (41); the inner elastic damping layer (42) is used to directly contact the multiphase flow introduced by the multiphase flow inlet (3) to absorb the impact kinetic energy of solid particles.

3. The integrated multiphase flow separation and pressurization device for oil and gas wellheads according to claim 2, characterized in that: The fluid monitoring channel consists of several blind holes (43) extending axially along the pipe wall of the bushing assembly (4); the multiple blind holes (43) are distributed circumferentially along the bushing assembly (4), and each blind hole (43) is not interconnected; the blind holes (43) are opened within the outer rigid pressure-bearing frame (41), and the preset physical safety limit is the interface between the outer rigid pressure-bearing frame (41) and the inner elastic damping layer (42); the blind ends of the blind holes (43) extend inward and The connection ends at the interface and does not penetrate the inner elastic damping layer (42); a passive pressure radio frequency tag (11) is also provided in the top of the bushing assembly (4), and a metal diaphragm (12) that can be deformed by the pressure inside the blind hole (43) is provided between the top port of the blind hole (43) and the passive pressure radio frequency tag (11). A loop antenna (13) is sealed at the corresponding position of the main channel tube (2). The deformation of the metal diaphragm (12) is used to change the resonance parameters of the passive pressure radio frequency tag (11).

4. The integrated multiphase flow separation and pressurization device for oil and gas wellheads according to claim 1, characterized in that: The inner elastic damping layer (42) at the bottom of the bushing assembly (4) is provided with a flow-regulating and flow-slowing structure; the flow-slowing structure includes a number of wedge-shaped ribs (44) distributed circumferentially along the inner wall, the flow-facing surface of the wedge-shaped ribs (44) is a water droplet-shaped streamlined curved surface, so as to sort out and smooth the introduced turbulent multiphase flow; and the wedge-shaped ribs (44) are integrally formed from the elastic material of the inner elastic damping layer (42) so as to directly absorb the impact kinetic energy of the fluid while guiding the flow.

5. The integrated multiphase flow separation and pressurization device for oil and gas wellheads according to claim 1, characterized in that: The barrier block (51) in the barrier assembly (5) is disposed in the cavity of the main housing (1) below the multiphase flow inlet (3). The bottom of the barrier block (51) is supported by a compression spring (52) arranged vertically in the cavity of the main housing (1). The top of the barrier block (51) is provided with a first magnetic pole (53), and the bottom of the bushing assembly (4) is provided with a second magnetic pole (54). The first magnetic pole (53) and the second magnetic pole (54) are configured as permanent magnets with the same polarity.

6. The integrated multiphase flow separation and pressurization device for oil and gas wellheads according to claim 5, characterized in that: Both the first magnetic pole (53) and the second magnetic pole (54) are made of high-temperature resistant permanent magnet material, and the first magnetic pole (53) and the second magnetic pole (54) are completely sealed in an isolation shell made of non-magnetic wear-resistant alloy so as to physically isolate the permanent magnet from the multiphase fluid.

7. The integrated multiphase flow separation and pressurization device for oil and gas wellheads according to claim 4, characterized in that: The bushing assembly (4) is the central hub for rectifying and transitioning the flow field inside the entire main shell (1). Several radial diversion side holes (45) are opened on the side of its pipe wall. The radial diversion side holes (45) are respectively connected to the liquid inlet (6) of the corresponding main channel pipe (2) on the periphery. A cutting component (7) is also provided in the main channel pipe (2) at the liquid inlet (6); the cutting component (7) includes a first magnet block (71) embedded in the outer wall of the bushing assembly (4) and a second magnet block (72) provided in the groove (74) of the main channel pipe (2); a first reset spring (73) is provided inside the groove (74), and the first reset spring (73) is fixedly connected to the second magnet block (72); the axial displacement of the bushing assembly (4) is synchronously converted into the spontaneous cutting action of the lateral branch channel.

8. The integrated multiphase flow separation and pressurization device for oil and gas wellheads according to claim 1, characterized in that: The top of the bushing assembly (4) is coaxially connected to a locking cylinder (46) with external threads via a rotary joint. The inner wall of the main channel pipe (2) is provided with a matching internal thread groove. The locking cylinder (46) is configured to be freely screwed into the internal thread groove in situ to apply a downward axial locking force to the bushing assembly (4) below without generating circumferential torque interference. The top of the locking cylinder (46) is provided with a lug (47). The top of the bushing assembly (4) is provided with a drain port (48).

9. The integrated multiphase flow separation and pressurization device for oil and gas wellheads according to claim 1, characterized in that: The top of the main housing (1) is detachably sealed with a pressure-bearing cap assembly; the pressure-bearing cap assembly includes a top cap (8) and a support column (9), the internal thread groove of the top cap (8) matches the external thread groove on the top of the main housing (1), and the support column (9) is fixedly connected to the top cap (8) to abut against the bushing assembly (4).

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