Underground multi-stage series-parallel multiphase cyclone separation device for high-liquid-yield oil well of offshore oilfield

Abstract

The invention relates to an underground multi-stage series-parallel multiphase cyclone separation device for an offshore oilfield high-liquid-yield oil well, which comprises an oil-water separation and extraction structure and an underground driving and reinjection structure, the oil-water separation and extraction structure comprises an upper centrifugal pump group and a multi-stage oil-water separation device, and the multi-stage oil-water separation device comprises a lower centrifugal pump group and a lower centrifugal pump group. The underground driving and reinjection structure comprises an oil displacement motor assembly and a lower centrifugal pump set, and while the oil displacement motor assembly drives the lower centrifugal pump set to rotate, a transmission shaft penetrating through the multi-stage oil-water separation device drives the upper centrifugal pump set to rotate; the oil-water separation and extraction structure treats and separates oil-water-sand mixed liquid in a large-displacement mode through multi-stage cyclone separation devices which are connected in series and in parallel, meanwhile, oil phases separated by hydrocyclones are gathered together through a plurality of parallel flow channels and discharged into an upper centrifugal pump set, and the oil phases are extracted to the ground after being sucked together. The separated sand phase is stored in the desilting cavity, and the water phase is reinjected underground; the oil-water-sand three-phase multistage separator is suitable for completing oil-water-sand three-phase multistage separation under the working condition of large treatment capacity of an offshore oilfield.

Description

Technical Field

[0001] The present invention relates to a device capable of efficiently separating a large-volume oil-water mixture on an offshore platform and realizing efficient separation of three-phase media of oil, water and sand under large-scale processing conditions in a narrow space underground. Specifically, it relates to an underground multi-stage series-parallel multi-phase cyclone separation device for an offshore oil field high-liquid-yield oil well. Background Art

[0002] At present, with the increase of oilfield exploitation, high water content is common in oilfields. With the in-depth development of offshore oilfields, especially when oilfields enter the mid-to-late exploitation stage, increasing the processing volume for large-volume oil production has become a major measure for stabilizing and increasing production in offshore oilfields. This has led to a large amount of production water being lifted to the ground, causing the water treatment capacity of offshore platforms and the transportation capacity of sea pipe liquid to reach a certain bottleneck, increasing the pressure on platform sewage treatment and environmental protection. At the same time, there is a small amount of sand phase in the mixed liquid underground. With long-term accumulation, each equipment in the oil production system will produce certain wear and tear, reducing the life of the equipment.

[0003] In order to solve the problem of increasing wastewater treatment volume in oil wells, technicians have proposed some solutions. Patent document 1: CN202011619048.2, which uses two submersible pumps to lift the oil and water separated by the oil-water cyclone in the downhole pipe string, respectively, although the lifting is completed after the separation is completed underground. However, under this scheme, an oil-water separator needs to be equipped with two submersible pumps with motors, which occupies a large space. At the same time, a single cyclone separator performs one separation, and the separation efficiency is limited. The range of treatment volume that can be coped with is small, and it cannot meet the water treatment capacity and transportation capacity under large treatment volume requirements. Patent document 2: CN202010206669.1, this invention uses a lifting system and a reinjection system to lift the separated liquid to the ground or reinject it underground, but the cost is high, which is not conducive to energy saving, environmental protection and large-scale promotion and application. In addition, the cyclone separator used in this invention is a more conventional cyclone with low separation efficiency. Secondly, exposing the motor directly to the liquid phase increases the risk of equipment corrosion, while ignoring the damage to the equipment life caused by the accumulation of sand in the system under long-term operation. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-stage series-parallel multiphase cyclone separation device for an offshore oil field high-liquid-yield oil well. The multi-stage series-parallel multiphase cyclone separation device for an offshore oil field high-liquid-yield oil well is used to solve the problems of low crude oil separation efficiency and small processing capacity range in the prior art.

[0005] The technical solution adopted by the present invention to solve its technical problems is: the multi-stage serially connected multi-phase cyclone separation device for high-liquid-yield oil wells in offshore oil fields comprises an oil-water separation and production structure and a downhole drive and reinjection structure. The oil-water separation and production structure is arranged on the downhole drive and reinjection structure. The oil-water separation and production structure comprises an upper centrifugal pump group and a multi-stage oil-water separation device. The downhole drive and reinjection structure comprises an oil-displacing motor assembly and a lower centrifugal pump group. The oil-displacing motor assembly drives the lower centrifugal pump group to rotate while driving the upper centrifugal pump group to rotate through a transmission shaft passing through the multi-stage oil-water separation device. The multi-stage oil-water separation device adopts a plurality of cyclones in parallel and multi-stage separations connected in series. Each stage of the oil-water separation device has a graded feed pipe, a graded combined sleeve, a graded cyclone group, and a graded cyclone. The cyclone group is composed of parallel cyclones, each graded feed pipe is sleeved outside the transmission shaft, the annulus between each graded feed pipe and the transmission shaft is a liquid inlet channel, and the adjacent two-stage feed pipes are connected by a guide channel. Each graded feed pipe is provided with a plurality of discharge ports distributed in an annular manner, and the liquid inlet channel is communicated with each cyclone through the discharge ports of each graded feed pipe and a plurality of tangential inlets correspondingly provided on the shell of each cyclone. The cyclone groups of each stage connected in series up and down are connected in parallel with respect to the liquid inlet channel; the graded combination sleeves are connected in sequence to form an assembled shell, and an overflow channel and an underflow channel are provided in the wall of the assembled shell, the overflow holes of each cyclone are communicated with the overflow channel, the underflow ports of each cyclone are communicated with the underflow channel, the upper end of the overflow channel is connected to the upper centrifugal pump group, and the lower end of the underflow channel is connected to the lower centrifugal pump group; The guide bearing is provided with a transmission shaft hole, the bearing cavity is centered around the transmission shaft hole, the transmission shaft passes through the transmission shaft hole, the bearing in the bearing cavity is sleeved outside the transmission shaft, the upper cavity and the lower cavity of the guide channel are connected through the vertical cavity, the upper cavity, the vertical cavity and the lower cavity are integrally connected to form a horizontal U-shaped groove, the bearing cavity is located in the U-shaped groove, and the guide channel connects the liquid inlet channel through the upper groove on the top of the upper cavity and the lower groove on the bottom of the lower cavity; the guide bearing is also provided with a fan-shaped channel, and the fan-shaped channel is located on the notch side of the U-shaped groove formed by the guide channel.

[0006] In the above scheme, the grading cyclone group is arranged in the grading combination sleeve, which is composed of a separation upper shell threadedly connected to a separation lower shell. The grading cyclone group includes four parallel cyclones, a fixed combination plate, a guide bearing, a sand guide cover and a sand settling chamber; the fixed combination plate is composed of an upper fixed plate and a lower fixed plate, which are respectively threadedly connected to the separation upper shell, the upper fixed plate has a transmission shaft hole and four overflow pipe fixing holes evenly arranged outside the transmission shaft hole, the lower fixed plate has a transmission shaft hole and four cyclone fixing holes evenly arranged outside the transmission shaft hole, and a groove is arranged on the wall of each cyclone fixing hole; each A spherical fixing is arranged on the outer wall of each cyclone, and a cyclone is installed at each cyclone fixing hole. The cyclone is fixed to the lower fixing plate through the spherical fixing and the groove, and the overflow pipe of the cyclone is fixed through the overflow pipe fixing hole. There is an annulus between the upper fixing plate and the separation upper shell, and the annulus is communicated with the overflow channel in the separation upper shell; the guide bearing is arranged below the cyclone, and there is a sand guide cover below the guide bearing and there is an annulus between the two, and the annulus is communicated with the bottom flow channel in the separation lower shell, and the lower end of the sand guide cover is threadedly connected to the sand settling chamber, and the annulus between the guide bearing and the sand guide cover is communicated with the sand settling chamber through the sand discharge hole of the sand guide cover.

[0007] In the above scheme, the cyclone includes a cyclone housing, a drainage oil filter cone, a variable pitch spiral flow channel and an inverted cone. The inverted cone is centrally arranged below the variable pitch spiral flow channel. The upper end of the variable pitch spiral flow channel is threadedly connected to the drainage oil filter cone. The variable pitch spiral flow channel and the drainage oil filter cone are provided with connected overflow holes. The upper end of the overflow hole is an overflow pipe. The lower end of the drainage oil filter cone is evenly provided with oil filter holes. The pitch of the upper part of the variable pitch spiral flow channel is greater than the pitch of the lower part.

[0008] In the above scheme, the graded cyclone group has three levels, namely, a primary cyclone separator group, a secondary cyclone separator group, and a tertiary cyclone separator group; the upper end of the separation upper shell of the primary cyclone separator group is threadedly connected to the inlet bridge channel, a plurality of liquid inlets are arranged on the outer wall of the inlet bridge channel, the transmission shaft passes through the transmission shaft hole of the inlet bridge channel and is connected to the upper centrifugal pump group, the upper end of the primary feed pipe opening is inserted into the slot of the inlet bridge channel, a liquid outlet is arranged at the slot, the liquid inlet is communicated with the liquid outlet, and the liquid outlet is communicated with the primary feed pipe; a bent overflow channel is also arranged in the inlet bridge channel, and the upper end of the overflow channel is connected to the upper centrifugal pump group.

[0009] In the above scheme, the lower end of the separation lower shell of the three-stage cyclone separator group is connected to the upper end of the confluence connection through threads, and the upper end of the lower bridge channel is placed on the lower end of the confluence connection and connected to the drive motor assembly.

[0010] In the above scheme, Tesla valves are respectively arranged at the overflow channels corresponding to the primary cyclone separator group, the secondary cyclone separator group, and the tertiary cyclone separator group; Tesla valves are respectively arranged at the underflow channels corresponding to the primary cyclone separator group, the secondary cyclone separator group, and the tertiary cyclone separator group.

[0011] In the above scheme, there are two overflow channels and four underflow channels.

[0012] When the hydrocyclone groups of each stage in the above scheme are working, the oil-water mixture containing a small amount of sand phase enters the primary feed pipe, the secondary feed pipe and the tertiary feed pipe through the liquid inlet respectively, and enters the interior of each hydrocyclone through the tangential inlet on the hydrocyclone shell. The cyclone field formed by the tangential inlet makes part of the light oil phase in the oil-water mixture converge to the center. As the drainage filter cone moves downward, part of the oil phase enters the drainage filter cone through the oil filter hole, and the remaining oil-water mixture is pressurized and enhanced in the cyclone field through the variable pitch spiral flow channel, so that the remaining oil phase is separated for the second time and enters the interior of the variable pitch spiral flow channel from the overflow hole, and is discharged upward from the overflow outlet together with the oil phase entering the drainage filter cone into the annulus above the fixed combination plate. The oil phase separated by the hydrocyclone groups of each stage converges to the overflow hole. In the flow channel, the oil phase is lifted upward step by step in the overflow channel, sucked into the upper centrifugal pump group, and then discharged through the upper oil pipe coupling, and finally produced to the ground; after separation, the water phase and a small amount of sand phase are discharged from the cyclone from the bottom flow port on the inverted cone, and then enter the annular cavity between the sand guide cover and the diversion channel through the fan-shaped channel on the diversion channel. The sand phase and part of the water phase fall into the first-level sand settling cavity, the second-level sand settling cavity and the third-level sand settling cavity through the sand discharge holes and settle. The water phase converges into the bottom flow channel. All water phases converge downward step by step along the bottom flow channel, and enter the inside of the confluence connection through the bottom flow channel on the confluence connection. Finally, all water phases enter the annular cavity inside the lower bridge channel from the confluence channel, and then enter the downhole driving and production structure from multiple drainage channels distributed along the circumference of its lower end. Beneficial Effects

[0013] 1. The oil-water-sand three-phase separation process device proposed by the present invention is applied to the large-volume processing conditions of the oil field. The multi-stage cyclones are connected in parallel to work in the form of series connection. The separation structures of each stage work independently, and the number of separation stages can be adjusted independently according to the processing volume requirements, which greatly increases the processing capacity and application scope of the device. At the same time, the process device is suitable for a single motor to drive two pump groups at the same time through a transmission shaft, which reduces the space occupied by the device and is conducive to improving applicability.

[0014] 2. The oil-water-sand three-phase separation structure proposed in the present invention has an innovative oil-water separator structure that can perform secondary enhanced oil-water separation through a variable pitch spiral flow channel, thereby improving the oil-water separation efficiency. At the same time, a small amount of sand phase in the mixed liquid can be separated, deposited and stored separately, thereby avoiding the long-term accumulation of sand phase into various process equipment and causing wear, which is beneficial to improving the equipment life.

[0015] 3. The separation structure of each level proposed by the present invention has two overflow channels designed for the overflow oil phase after separation, and four underflow channels designed for the water phase after separation. The overflow and underflow channels are arranged in parallel and do not affect each other. Finally, the overflow channels are gathered together and pumped out to the ground by the pump group. The underflow channels are gathered together and then pumped back into the ground by the pump group. This adapts to the transportation problem under large processing capacity conditions and ensures the stability of transportation during operation.

[0016] 4. The present invention realizes the efficient separation of oil, water and sand three-phase medium, the multi-stage separation structure is connected in series and runs in parallel at the same time, the multiple flow channels do not interfere with each other, and the layout of a single motor driving a double pump through a transmission shaft makes the process device flexible to cope with the large processing capacity of the oil field and the environmental conditions of the small underground space, further improving the scope of application of the device and improving the economic efficiency of oil field exploitation.

[0017] 5. The structural design of the present invention is used for one motor to drive two pump working systems. Under the environmental conditions and requirements of small underground space and large oil field processing conditions, the innovative cyclone design helps the separation structures at all levels to achieve efficient separation of oil, water and sand three-phase media. At the same time, multiple overflow channels and bottom flow channels are arranged in parallel and do not affect each other, ensuring the stability of transportation under large displacement conditions. It can achieve a device for efficient separation of oil, water and sand three-phase media under large processing conditions in a small underground space.

[0018] 6. The oil-water separation and production structure of the present invention processes and separates the oil-water-sand mixed liquid with a large displacement through a multi-stage cyclone separation device connected in series. At the same time, a plurality of parallel flow channels are used to gather the oil phases separated by all the cyclones together and discharge them into the upper centrifugal pump group, which are sucked into the upper oil pipe coupling together and then produced to the ground. The separated sand phase is stored in the sand settling chamber, and the water phase is finally gathered together and discharged into the downhole driving and reinjection structure; the downhole driving and reinjection structure sucks the separated and gathered water phases into the lower oil pipe coupling together through the lower centrifugal pump group and then reinjects them underground; and through the transmission shaft running through the center of the entire device, one motor can be used to drive two pump groups to work, which is suitable for large-scale processing in offshore oil fields. It can process a large-volume oil-water-sand mixed liquid in a limited space and complete the multi-stage separation of the three phases of oil, water and sand. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 (a) is the overall appearance diagram of the present invention; Figure 1 (b) is a cross-sectional view of the present invention.

[0020] Figure 2 (a) is the appearance diagram of the separation and extraction structure; Figure 2 (b) is a cross-sectional view of the separation and extraction structure.

[0021] Figure 3 Set up an exploded view for the oil-water separation and production structure.

[0022] Figure 4 (a) is the appearance diagram of the primary oil-water separation device; Figure 4 (b) is a cross-sectional view of the primary oil-water separation device.

[0023] Figure 5 (a) is the appearance diagram of the combined plate and cyclone structure; Figure 5 (b) is a cross-sectional view of the combined plate and cyclone structure.

[0024] Figure 6 (a) is the appearance diagram of the secondary oil-water separation device; Figure 6 (b) is a cross-sectional view of the secondary oil-water separation device.

[0025] Figure 7 (a) is the appearance diagram of the three-stage oil-water separation device; Figure 7 (b) is a cross-sectional view of the three-stage oil-water separation device.

[0026] Figure 8 This is an exploded view of the assembled shell.

[0027] Fig. 9 (a) is the appearance diagram of the drive and injection structure; Fig. 9 (b) is a cross-sectional view of the driving and reinjection structure.

[0028] In the figure, 101-inlet bridge channel, 1011-liquid inlet, 1012-liquid outlet, 1013-overflow channel, 102-transmission shaft, 103-first-stage feed pipe, 1031-first-stage annular discharge port, 104-fixed combination plate, 1041-cyclone fixing hole, 1042-groove, 1043-overflow pipe fixing hole, 105-first-stage separation upper shell, 1051-upper-stage overflow channel, 106-cyclone shell, 1061-tangential inlet, 1062-overflow hole, 1063-spherical fixed, 107-drainage filter cone, 1071-oil filter hole, 1072-overflow outlet, 108-variable pitch spiral flow channel, 1081-overflow inlet, 109-inverted cone, 1091-bottom flow outlet, 110-first-stage separation lower shell, 1101-next-stage overflow channel, 1102-next-stage bottom flow channel, 111-flow guide bearing, 1111 flow guide channel, 1114-fan-shaped channel, 112-sand guide cover, 1121-sand discharge hole, 113-secondary separation Upper shell, 1131-first-stage sand settling chamber, 1132-upper-secondary overflow channel, 1133-upper-secondary underflow channel, 114-secondary separation lower shell, 1142-lower-secondary overflow channel, 1143-lower-secondary underflow channel, 115-secondary feed pipe, 1151-secondary annular discharge port, 116-third-stage feed pipe, 1161-third-stage annular discharge port, 117-Tesla valve, 118-third-stage separation upper shell, 1181-secondary sand settling chamber, 1182-upper-third-stage overflow channel Channel, 1183-upper three-stage bottom flow channel, 119-three-stage separation lower shell, 1191-lower three-stage bottom flow channel, 120-convergence connection, 1201-bottom flow channel, 1202-convergence channel, 1203-three-stage sand settling chamber, 121-lower bridge channel, 1211-internal annular cavity, 1212-drainage channel, 122-upper centrifugal pump group, 123-upper oil pipe coupling, 201-lower shell, 202-drive motor assembly, 203-lower centrifugal pump group, 204-lower oil pipe coupling. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings: See also Figure 1-Figure 9The multi-stage downhole multiphase cyclone separation device for high-liquid-yield oil wells in offshore oil fields comprises an oil-water separation and production structure, a downhole drive and reinjection structure, the oil-water separation and production structure is arranged on the downhole drive and reinjection structure, the oil-water separation and production structure comprises an upper centrifugal pump group, a multi-stage oil-water separation device, the downhole drive and reinjection structure comprises an oil-displacing motor assembly, a lower centrifugal pump group, the oil-displacing motor assembly drives the lower centrifugal pump group to rotate, and at the same time, drives the upper centrifugal pump group to rotate through a transmission shaft passing through the multi-stage oil-water separation device; the multi-stage oil-water separation device adopts a plurality of cyclones in parallel and multi-stage separations connected in series, each stage of the oil-water separation device has a graded feed pipe, a graded combined sleeve, and a graded cyclone group, and the graded cyclone group consists of parallel cyclones The invention relates to a device structure, wherein each graded feed pipe is sleeved outside the transmission shaft, the annulus between each graded feed pipe and the transmission shaft is a liquid inlet channel, two adjacent graded feed pipes are connected by a guide channel, each graded feed pipe is provided with a plurality of discharge ports distributed in an annular manner, the liquid inlet channel is communicated with each cyclone through the discharge ports of each graded feed pipe and a plurality of tangential inlets correspondingly provided on each cyclone shell, and the cyclone groups of each grade connected in series up and down are connected in parallel with respect to the liquid inlet channel; the graded combination sleeves are connected in sequence to form an assembled shell, an overflow channel and an underflow channel are provided in the wall of the assembled shell, the overflow ports of each cyclone are communicated with the overflow channel, the underflow ports of each cyclone are communicated with the underflow channel, the upper end of the overflow channel is connected with the upper centrifugal pump group, and the lower end of the underflow channel is connected with the lower centrifugal pump group.

[0030] The oil-water separation and production structure includes an inlet bridge channel 101, a transmission shaft 102, a primary feed pipe 103, a fixed combination plate 104, a primary separation upper shell 105, a cyclone shell 106, a drainage filter cone 107, a variable pitch spiral flow channel 108, an inverted cone 109, a primary separation lower shell 110, a guide bearing 111, a sand guide cover 112, a secondary separation upper shell 113, a secondary separation lower shell 114, a secondary feed pipe 115, a tertiary feed pipe 116, a Tesla valve 117, and a tertiary The first-stage separation upper shell 118, the third-stage separation lower shell 119, the confluence connection 120, the lower bridge channel 121, the upper centrifugal pump group 122, and the upper oil pipe coupling 123; the upper end of the inlet bridge channel 101 is threadedly connected to the lower end of the upper centrifugal pump group 122, the upper end of the upper centrifugal pump group 122 is threadedly connected to the upper oil pipe coupling, and the lower end of the inlet bridge channel 101 is threadedly connected to the upper end of the first-stage separation upper shell 105; the internal thread of the first-stage separation upper shell 105 is connected to the fixed combination plate 104. The upper end of the variable pitch spiral flow channel 108 is threadedly connected to the lower end of the drainage oil filter cone 107 and then placed inside the cyclone shell 106. The upper end of the drainage oil filter cone 107 passes through the overflow hole 1062 at the center of the upper end of the cyclone shell 106 and is inserted into the overflow pipe fixing hole 1043 on the fixed combination plate 104. The lower end of the cyclone housing 106 is threadedly connected to the inverted cone 109, and the spherical fixing 1063 on its surface vertically enters from the lower end of the groove 1042 opened in the fixed assembly plate 104, and then rotates along the groove to be fixed together. The first-stage feed pipe 103 passes through the fixed assembly plate 104, and the upper end is connected to the lower end of the center of the inlet bridge channel 101, and the lower end is connected to the upper end of the guide bearing 111 in the first-stage separation lower housing 110.The lower end of the primary separation upper shell 105 is threadedly connected to the upper end of the primary separation lower shell 110; the lower end of the primary separation lower shell 110 is threadedly connected to the secondary separation upper shell 113, and the guide bearing 111 is placed inside it from above, and the position of the guide bearing 111 is limited by the annular boss structure on the inner wall of the primary separation lower shell 110; the primary sand settling chamber 1131 at the upper end of the secondary separation upper shell 113 is threadedly connected to the sand guide cover 112, and the lower end is threadedly connected to the secondary separation lower shell 114, and the fixed combination plate 104 and the cyclone components are placed inside it like the primary separation upper shell 105, and the secondary feed pipe 115 also passes through the fixed combination plate 104, the upper end is connected to the lower groove of the guide bearing 111 in the primary separation lower shell 110, and the lower end is connected to the upper groove of the guide bearing 111 in the secondary separation lower shell 114; the secondary separation lower shell 1 The guide bearing 111 is placed inside 14 in the same way as the first-stage separation lower shell 110, the lower end of the second-stage separation lower shell 114 is threadedly connected to the upper end of the third-stage separation upper shell 118 through a thread, and its lower end can also continue to be connected to the second-stage separation upper shell 113, and the lower end of the second-stage separation upper shell 113 is further threadedly connected to the second-stage separation lower shell 114, and the same parts are arranged inside, so that a multi-stage connection can be formed as needed; the fixed combination plate 104 and the cyclone components are arranged inside the third-stage separation upper shell 118 in the same way, the upper end of the third-stage feed pipe 116 is connected to the lower groove of the guide bearing 111 in the second-stage separation lower shell 114, the lower end of the third-stage separation upper shell 118 is threadedly connected to the upper end of the third-stage separation lower shell 119; the lower end of the third-stage separation lower shell 119 is threadedly connected to the upper end of the converging connection 120.

[0031] The inlet bridge channel 101 has six circumferentially distributed liquid inlets 1011, a liquid outlet 1012 in the center, and two overflow channels 1013 inside; the first-level feed pipe 103 is a hollow structure, and a first-level annular discharge port 1031 is opened on the surface; the fixed combination plate 104 is two fixed plates with threads on the surface, the lower fixed plate has four cyclone fixing holes 1041 and grooves 1042, and the upper fixed plate has four overflow pipe fixing holes 1043; the first-level separation upper shell 105 is a hollow structure with two upper-level overflow channels 1051 opened inside; the cyclone The housing 106 of the device is provided with a tangential inlet 1061, an overflow hole 106, and a spherical fixing 1063; the diversion filter cone 107 is a hollow structure, with an oil filter hole 1071 and an overflow outlet 1072; the variable pitch spiral flow channel 108 is a hollow structure, with an overflow inlet 1081; the inverted cone 109 is provided with an underflow outlet 1091; the first-stage separation lower housing 110 is a hollow structure, with two next-stage overflow channels 1101 and four next-stage underflow channels 1102; the guide bearing 111 is provided with a bearing and a guide channel 111 bypassing the bearing. 1 has two slots on the upper and lower sides, an upper slot, a lower slot and a fan-shaped channel 1114; the sand guide cover 112 has a sand discharge hole 1121 and a bearing hole 1122; the secondary separation upper shell 113 has a primary sand settling chamber 1131, two upper secondary overflow channels 1132, and four upper secondary bottom flow channels 1133; the secondary separation lower shell 114 is a hollow structure, with two lower secondary overflow channels 1142 and four lower secondary bottom flow channels 1143; the secondary feed pipe 115 is a hollow structure, with a secondary annular discharge port 1151 on the surface; the tertiary ... The pipe 116 is provided with a three-stage annular discharge port 1161; the three-stage separation upper shell 118 has a secondary sand settling chamber 1181, two upper three-stage overflow channels 1182, and four upper three-stage bottom flow channels 1183; the three-stage separation lower shell 119 is a hollow structure, and is provided with four lower three-stage bottom flow channels 1191; the confluence connection 120 has four bottom flow channels 1201, a confluence channel 1202, and a three-stage sand settling chamber 1203; the lower bridge channel 121 is provided with a bearing inside, has an internal annular cavity 1211, and has multiple drainage channels 1212 distributed around the lower end. The upper end of the lower bridge channel 121 is placed at the lower end of the confluence connection 120 and connected to the drive motor assembly 202. The Tesla valve 117 is placed in the overflow and bottom flow channels of each level to prevent backflow. The transmission shaft 102 runs through the oil-water separation and production structure and is connected to the pump and motor part through the corresponding shaft connection device, and starts working after connection.

[0032] The separation structure adopts multiple cyclones in parallel and multi-stage separation in series, and the welfare structure technology can be adjusted according to needs. At the same time, the upper overflow channel 1051, the upper second overflow channel 1132, the upper third overflow channel 1182 and the first overflow channel 1013 are two, and the lower bottom flow channel 1102, the lower second bottom flow channel 1143, the lower third bottom flow channel 1191 and the bottom flow channel 1021 are four. Multiple separation devices work at the same time, and multiple flow channels transport together to meet the large-displacement working conditions of the equipment.

[0033] During operation, the oil-water mixture containing a small amount of sand phase enters the device through the liquid inlet 1011, and then flows into the primary feed pipe 103, the guide channel 1111 inside the guide bearing 111, the secondary feed pipe 115, the guide channel 1111 inside the next guide bearing 111, and the tertiary feed pipe 116 from the liquid outlet 1012 in sequence. Then, the mixed liquid passes through the primary annular discharge port 1031, the secondary annular discharge pipe 1151, and the tertiary annular discharge pipe 1161, and enters the annular space between the combined plate 104 and the primary separation upper shell 105, the secondary separation upper shell 113, and the tertiary separation upper shell 118, and enters the cyclone through the tangential inlet 1061 on the cyclone shell 106, and passes through the tangential inlet The cyclone field formed by 1061 makes part of the light oil phase in the mixed liquid converge to the center. As the drainage filter cone 107 moves downward, part of the oil phase enters the drainage filter cone 107 through the oil filter hole 1071, and the remaining mixed liquid is pressurized and enhanced in the cyclone field through the variable pitch spiral flow channel 108, so that the remaining oil phase is separated for the second time and enters the variable pitch spiral flow channel 108 from the overflow inlet 1081. Then, it is discharged from the overflow outlet 1072 into the annular space above the fixed combination plate 104 together with the oil phase entering the drainage filter cone 107, and enters the upper overflow channel 1051, the upper second overflow channel 1132, and the upper third overflow channel 1182 respectively. All the oil phases flow along the upper third overflow channel 118 2. The oil phase of the lower secondary overflow channel 1142 merges with the oil phase of the upper secondary overflow channel 1132, and then merges with the oil phase of the upper overflow channel 1051 along the lower overflow channel 1101. Finally, all the oil phases are sucked from the overflow channel 1013 into the upper centrifugal pump group 122, and then discharged from the upper oil pipe coupling 123 to the surface. The separated water phase and a small amount of sand phase are discharged from the cyclone from the bottom flow port 1091 on the inverted cone 109, and then enter the annular cavity between the sand guide cover 112 and the guide channel 111 through the fan-shaped channel 1114 on the guide channel 111. The sand phase and part of the water phase fall into the first sand settling cavity 1131, the second sand settling cavity 118, and the third sand settling cavity 1203 through the sand discharge hole 1121. When the subsequent device is taken out, the internal sand can be emptied at the same time, and the water phase enters the next-level bottom flow channel 110), the next-level bottom flow channel 1143, and the next-level bottom flow channel 1191 respectively. All water phases merge with the next-level bottom flow channel 1102 and the upper-level bottom flow channel 1133 and the lower-level bottom flow channel 1143, and then enter the interior of the confluence connection 120 through the upper bottom flow channel 1201 of the confluence connection 120 along the upper tertiary bottom flow channel 1183 and the water phase of the lower tertiary bottom flow channel 1191. Finally, all water phases enter the internal annular cavity 1211 of the bridge channel 121 from the confluence channel 1202, and then enter the downhole drive and production structure from the multiple drainage channels 1212 distributed circumferentially at its lower end.

[0034] The downhole drive and reinjection structure includes: a lower shell 201, a drive motor assembly 202, a lower centrifugal pump group 203, and a lower oil pipe coupling 204; the upper end of the lower shell 201 is threadedly connected to the lower end of the confluence connection 120, and the lower end is threadedly connected to the lower centrifugal pump group 203, and the drive motor assembly 202 is placed inside the lower shell 201; the upper end of the drive motor assembly 202 is connected to the lower end of the bridge channel 121, and the central internal coupling is connected to the transmission shaft 102; the lower end of the lower centrifugal pump group 203 is threadedly connected to the lower oil pipe coupling 204.

[0035] During operation, the driving motor assembly 202 drives the lower centrifugal pump group 203 to rotate, and the transmission shaft 102 rotates at the same time, thereby driving the upper centrifugal pump group 122 to work. The water phase gathered after the oil-water separation and the separation from the production structure enters the annular space area between the lower shell 201 and the driving motor assembly 202 through the drainage channel 1212 on the bridge channel 121, and is finally sucked into the lower centrifugal pump group 203, discharged from the lower oil pipe coupling 204, and finally injected back into the underground.

[0036] The present invention is described in more detail as follows: This kind of multi-stage series-connected parallel multiphase cyclone separation device for high-liquid-yield oil wells in offshore oil fields is as follows: Figure 1 As shown, the device is placed vertically in the downhole pipeline. When working, the sand-containing oil-water mixture enters the device from the liquid inlet 1011. After being separated by the separation devices at various levels, the oil phase gathered in the overflow channels of each level is sucked into the upper oil pipe coupling 123 by the upper centrifugal pump group 122, and then the discharge device is lifted to the ground. The separated water phase is finally sucked into the lower oil pipe coupling 204 by the lower centrifugal pump group 203 through the bottom flow channels of each level, and then injected back into the well. It should be noted that the device is penetrated by a transmission shaft 102 from top to bottom, so the pump structure after the upper and lower ends of the device are connected can be connected through the transmission shaft 102 to work simultaneously, which is suitable for a system in which one motor drives two pumps; Separation and extraction structure Figure 2As shown, the transmission shaft 102 drives the lower and upper centrifugal pump groups 122 to rotate, and the mixed liquid entering the liquid inlet 1011 flows into the feed pipes of each level from the liquid outlet 1012 in sequence, and enters the separation part from the annular discharge ports of the feed pipes of each level, such as the first-level feed pipe 103 and the first-level annular discharge port 1031 in the figure. After separation by the separation devices at each level, the oil phase merges with the oil phase of the upper second-level overflow channel 1132 along the upper third-level overflow channel 1182 and the lower second-level overflow channel 1142, and then merges with the oil phase of the upper first-level overflow channel 1051 along the lower overflow channel 1101. Finally, all the oil phases are sucked and discharged from the overflow channel 1013 by the upper centrifugal pump group 122 into the upper oil pipe coupling 123, and then the discharge device is lifted to the ground. A Tesla valve 117 is placed in the flow channel to stabilize the flow and prevent backflow. It is worth noting that the two-level separation structure is installed twice in a cycle in the figure, and the number of stages of the cycle installation can be freely adjusted according to needs during operation.

[0037] like Figure 3 and Figure 4 As shown, the oil-water mixture containing a small amount of sand phase enters the device through the liquid inlet 1011, and then flows into the first-level feed pipe 103 from the liquid outlet 1012. Subsequently, the mixed liquid passes through the first-level annular outlet 1031, enters the annular space between the combined plate 104 and the first-level separation upper shell 105, and enters the cyclone through the tangential inlet 1061 on the cyclone shell 106. After cyclone separation, the light phase oil phase is discharged from the overflow outlet 1072 into the annular space above the combined plate 104, enters the upper overflow channel 1051, and merges with the oil phase separated by the secondary and tertiary separation structures flowing in from the next overflow channel 1101. Finally, all the oil phases are sucked into the upper centrifugal pump group 122 from the overflow channel 1013. After separation, the water phase and a small amount of sand phase are discharged from the cyclone from the bottom flow port 1091 on the inverted cone 109, and then enter the annular cavity between the sand guide cover 112 and the guide bearing 111 through the fan-shaped channel 1114 on the guide bearing 111. The sand phase and part of the water phase fall into the primary sand settling cavity 1131 through the sand discharge hole 1121 and are deposited. When the subsequent device is taken out, the internal sand can be emptied by the way, and the water phase enters the next-level bottom flow channel 1102, and then flows into the upper secondary bottom flow channel 1133 in the secondary separation structure. The Tesla valve 117 is placed in each flow channel to stabilize the flow and prevent backflow. The mixed liquid in the primary feed pipe 103 passes through the guide channel 1111 inside the guide bearing 111 and flows into the secondary feed pipe 115 in the secondary separation structure; the appearance and cross-sectional views of the fixed combination plate and the cyclone structure are shown in the figure. Figure 5As shown, the upper end of the variable pitch spiral flow channel 108 is threadedly connected with the lower end of the drainage filter cone 107 and then placed inside the cyclone housing 106. The upper end of the drainage filter cone 107 passes through the overflow hole 1062 at the center of the upper end of the cyclone housing 106 and is inserted into the overflow pipe fixing hole 1043 on the fixed assembly plate 104. The lower end of the cyclone housing 106 is threadedly connected with the inverted cone 109, and the spherical fixing 1063 on its surface vertically enters from the lower end of the groove 1042 opened in the fixed assembly plate 104, and then rotates along the groove to be clamped and fixed together. The mixed liquid enters the cyclone through the tangential inlet 1061 on the cyclone housing 106. The cyclone field formed by the tangential inlet 1061 makes part of the light oil phase in the mixed liquid converge toward the center. As the drainage filter cone 107 moves downward, part of the oil phase enters the drainage filter cone 107 through the oil filter hole 1071, and the remaining mixed liquid is pressurized and enhanced in the cyclone field through the variable pitch spiral flow channel 108, so that the remaining oil phase is secondary separated and enters the variable pitch spiral flow channel 108 from the overflow inlet 1081, and then is discharged from the overflow outlet 1072 into the annular space above the combined plate 104 together with the oil phase entering the drainage filter cone 107. After separation, the water phase and a small amount of sand phase are discharged from the cyclone from the bottom flow port 1091 on the inverted cone 109. The inverted cone 109 plays a role in improving the separation of oil and water.

[0038] The appearance and cross-sectional view of the secondary separation structure are as follows: Figure 6As shown in (a) and (b), the mixed liquid flowing from the primary separation structure into the secondary feed pipe 115 passes through the secondary annular discharge port 1151, enters the annular space between the combined plate 104 and the secondary separation upper shell 113, and enters the cyclone through the tangential inlet 1061 on the cyclone shell 106. After cyclone separation, the light phase oil phase is discharged from the overflow outlet 1072 into the annular space above the combined plate 104, enters the upper secondary overflow channel 1132, and merges with the oil phase separated by the tertiary separation structure flowing into the lower secondary overflow channel 1142, and then merges into the next overflow channel 1101. After separation, the water phase and a small amount of sand phase are discharged from the cyclone from the bottom flow port 1091 on the inverted cone 109, and then enter the annular cavity between the sand guide cover 112 and the guide bearing 111 through the fan-shaped channel 1114 on the guide bearing 111. The sand phase and part of the water phase fall into the secondary sand settling cavity 1181 through the sand discharge hole 1121 and are deposited. When the subsequent device is taken out, the internal sand can be emptied at the same time, and the water phase enters the lower secondary bottom flow channel 1143, and flows into the upper third bottom flow channel 1183 in the three-stage separation structure together with the water phase after the first-stage separation. The Tesla valve 117 is placed in each flow channel to stabilize the flow and prevent backflow. The mixed liquid in the secondary feed pipe 115 passes through the guide channel 1111 inside the second guide bearing 111 and flows into the third-stage feed pipe 116 in the three-stage separation structure. It is worth mentioning that, in addition to being connected to the tertiary separation structure, the secondary separation structure can also be further connected to the secondary separation structure, so as to flexibly adjust the number of separation structures according to the required range of mixed liquid processing volume.

[0039] The appearance and cross-sectional view of the three-stage separation structure are as follows: Figure 7As shown in (a) and (b), the mixed liquid flowing from the secondary separation structure into the tertiary feed pipe 116 passes through the tertiary annular discharge port 1161, enters the annular space between the combined plate 104 and the tertiary separation upper shell 118, and enters the cyclone through the tangential inlet 1061 on the cyclone shell 106. After cyclone separation, the light phase oil phase is discharged from the overflow outlet 1072 into the annular space above the combined plate 104, enters the upper tertiary overflow channel 1182, and then flows into the lower secondary overflow channel 1142. After separation, the water phase and a small amount of sand phase are discharged from the cyclone from the bottom flow port 1091 on the inverted cone 109 and enter the annular cavity above the sand guide cover 112. The sand phase and part of the water phase fall into the third-level sand settling cavity 1203 through the sand discharge hole 1121 and are deposited. When the subsequent device is taken out, the internal sand can be emptied at the same time, and the water phase enters the lower third-level bottom flow channel 1191, and enters the inside of the confluence connection 120 through the bottom flow channel 1201 on the confluence connection 120 together with the water phase after the first and second separations. The Tesla valve 117 is placed in each flow channel to stabilize the flow and prevent backflow. Finally, all the water phases enter the internal annular cavity 1211 of the bridge channel 121 from the confluence channel 1202, and then enter the downhole drive and production structure 2 from multiple drainage channels 1212 distributed circumferentially at its lower end; Figure 8 Schematic diagrams of different observation angles of the overflow channel 101 on the inlet bridge channel 101, the upper overflow channel 1051 on the primary separation upper shell 105, the next overflow channel 1101 and the next underflow channel 1102 on the primary separation lower shell 110, the upper secondary overflow channel 1132 and the upper secondary underflow channel 1133 on the secondary separation upper shell 113, the lower secondary overflow channel 1142 and the lower secondary underflow channel 1143 on the secondary separation lower shell 114, the upper third overflow channel 1182 and the upper third underflow channel 1183 on the third-stage separation upper shell 118, the lower third underflow channel 1191 on the third-stage separation lower shell 119, and the underflow channel 1201 on the confluence connection 120 are shown; the appearance and cross-sectional view of the driving and extraction structure are shown as follows: Fig. 9 As shown in (a) and (b), the driving motor assembly 202 drives the lower centrifugal pump group 203 to rotate, and the water phase gathered after the oil-water separation and the separation of the production structure 1 enters the annular space area between the lower shell 201 and the driving motor assembly 202 through the drainage channel 1212 on the bridge channel 121, and is then sucked into the lower centrifugal pump group 203, discharged from the lower oil pipe coupling 204, and finally injected back into the underground.

[0040] Aiming at the large-volume processing conditions in oil fields and the environmental conditions of small underground space, the present invention provides a process device that can connect multiple separation structures in series and operate in parallel. Each stage of separators can realize the efficient separation of the three-phase medium of oil, water and sand. The overflow and bottom flow channels are arranged in parallel and do not affect each other, ensuring the stability of transportation during large-volume processing. At the same time, it is suitable for the structural design of one motor driving two pump working systems, so that the invention can be used in the environmental conditions of small underground space, improving applicability. The innovative cyclone design helps to improve the oil-water separation efficiency, and the design of the sand settling structure prevents the sand phase from accumulating for a long time and entering various process equipment to cause wear, thereby enhancing the economy of the entire process device.

Claims

1. A multi-stage serially connected multiphase cyclone separation device for an offshore oilfield high-liquid-yield oil well, characterized in that: The multi-stage serially connected multiphase cyclone separation device for high-liquid-yield oil wells in offshore oil fields comprises an oil-water separation and production structure and a downhole drive and reinjection structure. The oil-water separation and production structure is arranged on the downhole drive and reinjection structure. The oil-water separation and production structure comprises an upper centrifugal pump group and a multi-stage oil-water separation device. The downhole drive and reinjection structure comprises an oil-displacing motor assembly and a lower centrifugal pump group. The oil-displacing motor assembly drives the lower centrifugal pump group to rotate while driving the upper centrifugal pump group to rotate through a transmission shaft passing through the multi-stage oil-water separation device. The multi-stage oil-water separation device adopts a plurality of cyclones in parallel and multi-stage separations connected in series. Each stage of the oil-water separation device has a graded feed pipe, a graded combined sleeve, and a graded cyclone group. The graded cyclone group consists of parallel cyclones. The structure is as follows: each graded feed pipe is sleeved outside the transmission shaft, the annulus between each graded feed pipe and the transmission shaft is a liquid inlet channel, two adjacent graded feed pipes are connected by a guide channel, each graded feed pipe is provided with a plurality of discharge ports distributed in an annular manner, the liquid inlet channel is communicated with each cyclone through the discharge ports of each graded feed pipe and a plurality of tangential inlets correspondingly provided on each cyclone shell, and the cyclone groups of each grade connected in series up and down are connected in parallel with respect to the liquid inlet channel; the graded combination sleeves are connected in sequence to form an assembled shell, an overflow channel and an underflow channel are provided in the wall of the assembled shell, the overflow holes of each cyclone are communicated with the overflow channel, the underflow ports of each cyclone are communicated with the underflow channel, the upper end of the overflow channel is connected to the upper centrifugal pump group, and the lower end of the underflow channel is connected to the lower centrifugal pump group; The guide bearing is provided with a transmission shaft hole, the bearing cavity is centered around the transmission shaft hole, the transmission shaft passes through the transmission shaft hole, the bearing in the bearing cavity is sleeved outside the transmission shaft, the upper cavity and the lower cavity of the guide channel are connected through the vertical cavity, the upper cavity, the vertical cavity and the lower cavity are integrally connected to form a horizontal U-shaped groove, the bearing cavity is located in the U-shaped groove, and the guide channel connects the liquid inlet channel through the upper groove on the top of the upper cavity and the lower groove on the bottom of the lower cavity; the guide bearing is also provided with a fan-shaped channel, and the fan-shaped channel is located on the notch side of the U-shaped groove formed by the guide channel.

2. The multi-stage serially connected multi-phase cyclone separation device for high-liquid-yield oil wells in offshore oil fields according to claim 1, characterized in that: The grading cyclone group is arranged in the grading combination sleeve, which is composed of a separation upper shell threadedly connected to a separation lower shell. The grading cyclone group includes four parallel cyclones, a fixed combination plate, a guide bearing, a sand guide cover and a sand settling chamber; the fixed combination plate is composed of an upper fixed plate and a lower fixed plate, which are respectively threadedly connected to the separation upper shell, the upper fixed plate has a transmission shaft hole and four overflow pipe fixing holes evenly arranged outside the transmission shaft hole, the lower fixed plate has a transmission shaft hole and four cyclone fixing holes evenly arranged outside the transmission shaft hole, and a groove is arranged on the wall of each cyclone fixing hole; each A spherical fixing is arranged on the outer wall of the cyclone, and a cyclone is installed at each cyclone fixing hole. The cyclone is fixed to the lower fixing plate through the spherical fixing and the groove, and the overflow pipe of the cyclone is fixed through the overflow pipe fixing hole. There is an annulus between the upper fixing plate and the separation upper shell, and the annulus is communicated with the overflow channel in the separation upper shell; the guide bearing is arranged under the cyclone, and there is a sand guide cover under the guide bearing and there is an annulus between the two, and the annulus is communicated with the bottom flow channel in the separation lower shell, and the lower end of the sand guide cover is threadedly connected to the sand settling chamber, and the annulus between the guide bearing and the sand guide cover is communicated with the sand settling chamber through the sand discharge hole of the sand guide cover.

3. The multi-stage serially connected multi-phase cyclone separation device for high-liquid-yield oil wells in offshore oil fields according to claim 2, characterized in that: The cyclone comprises a cyclone housing, a drainage oil filter cone, a variable pitch spiral flow channel and an inverted cone. The inverted cone is centrally arranged below the variable pitch spiral flow channel. The upper end of the variable pitch spiral flow channel is threadedly connected to the drainage oil filter cone. The variable pitch spiral flow channel and the drainage oil filter cone are provided with connected overflow holes. The lower end of the drainage oil filter cone is evenly provided with oil filter holes. The pitch of the upper part of the variable pitch spiral flow channel is greater than the pitch of the lower part.

4. The multi-stage serially connected multi-phase cyclone separation device for high-liquid-yield oil wells in offshore oil fields according to claim 3, characterized in that: The grading cyclone group has three stages, namely a primary cyclone separator group, a secondary cyclone separator group, and a tertiary cyclone separator group; the upper end of the separation upper shell of the primary cyclone separator group is threadedly connected to the inlet bridge channel, a plurality of liquid inlets are arranged on the outer wall of the inlet bridge channel, a transmission shaft passes through the transmission shaft hole of the inlet bridge channel and is connected to the upper centrifugal pump group, the upper end of the primary feed pipe opening is inserted into the slot of the inlet bridge channel, a liquid outlet is arranged at the slot, the liquid inlet is communicated with the liquid outlet, and the liquid outlet is communicated with the primary feed pipe; a bent overflow channel is also arranged in the inlet bridge channel, and the upper end of the overflow channel is connected to the upper centrifugal pump group.

5. The multi-stage serially connected multi-phase cyclone separation device for high-liquid-yield oil wells in offshore oil fields according to claim 4 is characterized in that: The lower end of the separation lower shell of the three-stage cyclone separator group is connected to the upper end of the confluence connection through threads, and the upper end of the lower bridge channel is placed on the lower end of the confluence connection and connected to the drive motor assembly.

6. The multi-stage serially connected multi-phase cyclone separation device for high-liquid-yield oil wells in offshore oil fields according to claim 5, characterized in that: The overflow channel is provided with Tesla valves at the positions corresponding to the primary cyclone separator group, the secondary cyclone separator group, and the tertiary cyclone separator group; the underflow channel is provided with Tesla valves at the positions corresponding to the primary cyclone separator group, the secondary cyclone separator group, and the tertiary cyclone separator group.

7. The multi-stage serially connected multi-phase cyclone separation device for high-liquid-yield oil wells in offshore oil fields according to claim 6, characterized in that: There are two overflow channels and four underflow channels.

8. The multi-stage serially connected multi-phase cyclone separation device for high-liquid-yield oil wells in offshore oil fields according to claim 7, characterized in that: When the hydrocyclone groups of each stage are working, the oil-water mixture containing a small amount of sand phase enters the primary feed pipe, the secondary feed pipe, and the tertiary feed pipe through the liquid inlet, and enters the interior of each hydrocyclone through the tangential inlet on the outer shell of each hydrocyclone. The cyclone field formed by the tangential inlet makes part of the light oil phase in the oil-water mixture converge to the center. As the drainage filter cone moves downward, part of the oil phase enters the drainage filter cone through the oil filter hole, and the remaining oil-water mixture is pressurized and enhanced in the cyclone field through the variable pitch spiral flow channel, so that the remaining oil phase is secondary separated and enters the interior of the variable pitch spiral flow channel from the overflow hole, and is discharged upward from the overflow outlet together with the oil phase entering the drainage filter cone into the annulus above the combined plate. The oil phase separated by the hydrocyclone groups of each stage converges to the overflow channel, and the oil phase is lifted upward step by step in the overflow channel, sucked into the upper centrifugal pump group, and then discharged through the upper oil pipe coupling, and finally produced to the ground; After separation, the water phase and a small amount of sand phase are discharged from the cyclone from the bottom flow port on the inverted cone, and then enter the annular cavity between the sand guide cover and the diversion channel through the fan-shaped channel on the diversion channel. The sand phase and part of the water phase fall into the first-level sand settling cavity, the second-level sand settling cavity and the third-level sand settling cavity through the sand discharge holes and settle. The water phase converges into the bottom flow channel. All water phases converge downward along the bottom flow channel step by step, and enter the inside of the confluence connection through the bottom flow channel on the confluence connection. Finally, all water phases enter the annular cavity inside the lower bridge channel from the confluence channel, and then enter the downhole driving and production structure from multiple drainage channels distributed along the circumference at its lower end.

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