Offshore oil field double-pump suction type separation device capable of widening split ratio and high in treatment capacity

Abstract

The invention relates to an offshore oilfield double-pump suction type separation device with broadened split ratio and high treatment capacity, which comprises an underground oil-water separation and extraction module and an underground driving and reinjection module, the underground oil-water separation and extraction module comprises an upper long outer sleeve, a long shaft, a shaft sleeve and a multi-stage series cyclone, the multi-stage series cyclone is arranged in the upper long outer sleeve, the upper end of the long shaft penetrates through the bearing installer to be connected with the upper centrifugal pump, the lower end of the long shaft sequentially penetrates through the multi-stage series cyclone and the bridge type channel, and the lower end of the long shaft penetrates out of a bearing seat of the bridge type channel to be connected with an upper connecting shaft of the underground driving and reinjection module; a motor of the underground driving and reinjection module is arranged in an inner sleeve, an annular space between the inner sleeve and a lower long outer sleeve is a flow guide channel, and a water phase separated by the multi-stage series cyclone flows into the flow guide channel from a lower bottom flow hole of a bridge type channel, bypasses the motor in the inner sleeve and is reinjected underground. The separation efficiency is effectively improved, and the cost is reduced while the yield of an oil field is improved.

Description

Technical Field

[0001] The present invention relates to a device used in the field of underground oil-water separation and capable of realizing efficient separation of oil and water in a narrow underground space, and specifically relates to an offshore oil field double-pump suction type widened diversion ratio high-processing capacity separation device. Background Art

[0002] After decades of exploitation, China's oil fields are now facing a very serious problem of high water content. Especially with the rapid development of my country's economy, the demand for oil in industries such as industry and automobiles is also increasing. Several major oil fields on land in the country have entered the stage of high water content and high recovery. When the oil field enters the exploitation stage, as the exploitation time increases, the energy of the oil field itself is continuously released, and the pressure of the oil layer continues to decrease. After the pressure drops to a certain level, in order to make up for the underground deficit after the crude oil is extracted, the oil field must be injected with water to increase the pressure of the oil layer, thereby stabilizing the oil production and recovery rate. In the later stage of oil field exploitation, when the water content of the oil field reaches more than 90%, more and more water is lifted from the oil field, the recovery rate drops sharply, the cost of lifting the oil-water mixture to the ground increases, and the difficulty of exploitation is also increasing, which leads to a decrease in the exploitation value of the oil field. The oil wells are close to the economic exploitation limit due to the increase in water content, causing the oil field to stop production prematurely. The high water content of the output fluid increases the difficulty of treatment and oil-water separation. At the same time, the cost of treating ground sewage increases, and the chemical reagents used in sewage treatment will also affect the ecological environment and cause land pollution.

[0003] In order to improve the recovery rate of oil wells, technicians have proposed some solutions. Patent document 1, CN20171090217.3, adopts the same well injection and production process. The device includes a linear motor oil pump, a linear motor water injection pump and an oil-water separator. However, the efficiency of the separation module is low. The oil-water separation part adopts gravity separation, and the processing capacity is low. It cannot be used in working occasions with large processing capacity. In addition, the tubing string adopts dual motors, which is costly and requires higher maintenance costs for the motors. Patent document 2, CN202110411248.7, uses the density difference between gas and liquid to complete gas-liquid separation through gravity sedimentation in the gas-liquid separation part. However, under this solution, the gravity sedimentation separation speed is slow. Under the working conditions where the flow rate of each phase medium is very fast, it is difficult to achieve efficient separation. Summary of the invention

[0004] The purpose of the present invention is to provide an offshore oil field double pump suction type widened diversion ratio high processing capacity separation device, which is used to solve the problems of low separation efficiency and high cost of oil-water separation devices in the prior art when processing high-water-content crude oil in a small space underground.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows: the offshore oil field double pump suction widened split ratio high processing capacity separation device comprises a downhole oil-water separation and production module and a downhole drive and reinjection module, the downhole oil-water separation and production module comprises an upper long outer casing, an upper centrifugal pump, a bearing mounter, a long shaft, a shaft sleeve, and a multi-stage series cyclone, a liquid inlet hole is arranged on the upper part of the upper long outer casing, the multi-stage series cyclone is arranged in the upper long outer casing, the upper end of the long shaft passes through the bearing mounter and is connected to the upper centrifugal pump, the lower end of the long shaft passes through the multi-stage series cyclone and the bridge channel in sequence, the lower end of the long shaft passes through the bearing seat of the bridge channel and is connected to the upper connecting shaft of the downhole drive and reinjection module; The upper end of the bearing installer is pre-tightened with the upper centrifugal pump by bolts. The bearing installer includes a mounting cylinder. The center of the mounting cylinder is a bearing chamber. The bearing chamber and the inner wall of the mounting cylinder are connected by an arc block. There is an arc cavity between the bearing chamber and the mounting cylinder. The upper cavity of the bearing chamber and the lower cavity of the bearing chamber are connected through the arc cavity to form an oil delivery channel. The oil delivery channel is connected to the total overflow port of the multi-stage series cyclone. A shaft sleeve is arranged at the center of the multi-stage series cyclone, and the shaft sleeve is arranged outside the long axis. A long axis hole is arranged at the top center of the bridge channel, and upper and lower flow holes are distributed around the long axis hole. The upper part of the bearing seat is located in the cavity, and the lower part of the bearing seat passes through the bottom of the bridge channel. The lower part of the bearing seat is provided with an external thread, and the bottom flow hole is arranged at the bottom of the bridge channel. The upper bottom flow hole, the cavity, and the lower bottom flow hole are connected. The downhole drive and reinjection module includes an upper connecting shaft, a motor, a lower connecting shaft and a lower centrifugal pump. The inner casing is coaxially arranged in the lower long outer casing. The upper connecting shaft, the motor and the lower connecting shaft connected in sequence are arranged in the inner casing. The lower connecting shaft is connected to the lower centrifugal pump. The annular space between the inner casing and the lower long outer casing is a diversion channel. The lower bottom flow hole of the bridge channel is connected to the diversion channel. The water phase separated by the multi-stage series cyclone flows into the diversion channel from the lower bottom flow hole of the bridge channel, cannot enter the inner casing, bypasses the motor in the inner casing, enters the lower centrifugal pump from the diversion channel, and is reinjected underground.

[0006] In the above scheme, the multi-stage series cyclone is composed of three cyclones connected in series: a primary cyclone, a secondary cyclone and a tertiary cyclone.

[0007] In the above scheme, the primary cyclone comprises a primary shell, a sleeve, and a primary overflow pipe. The primary shell is composed of a total overflow cylinder arranged at the upper end of a primary cone. The sleeve is centrally arranged in the primary cone. The outer edge of the upper port of the sleeve is fixedly connected to the inner wall of the primary shell through a support sheet. A total overflow port is arranged between the support sheet and the upper port of the primary shell. The lower port of the sleeve is located in the primary cone and is provided with an inner liner. The outer wall of the lower port of the inner liner is a conical structure. The primary overflow pipe is coaxially arranged outside the sleeve. The pipe mouth of the primary overflow pipe is fixed in the total overflow cylinder through an eccentric fixing ring. The eccentric fixing ring and the inner wall of the total overflow cylinder have a primary overflow port. The upper port of the annulus between the primary overflow pipe and the sleeve is communicated with the total overflow cylinder. An annular hole is provided between the primary overflow pipe and the inner liner. A tangential inlet is arranged near the lower port of the inner liner at the primary cone. The tangential inlet is arranged corresponding to the liquid inlet. An outer step is arranged on the outer wall of the primary cone. The annular port between the lower port of the primary cone and the lower port of the primary overflow pipe is a primary underflow port.

[0008] In the above scheme, the secondary cyclone includes a secondary shell, a spiral flow channel, and a secondary overflow pipe. The primary overflow pipe extends downward to the straight section of the secondary shell and forms a spiral flow channel on the outer wall. The secondary overflow pipe is coaxially arranged between the shaft sleeve and the primary overflow pipe. The annular space between the secondary overflow pipe and the primary overflow pipe is the secondary overflow channel. The upper port of the secondary overflow channel is connected to the main overflow cylinder, and the lower port of the secondary overflow channel is the secondary overflow port. The bottom of the secondary shell is the secondary cyclone base, and the lower inlet of the annular cavity between the secondary shell and the secondary overflow pipe is the secondary bottom flow port.

[0009] In the above scheme, the three-stage cyclone includes a three-stage cyclone end cover and a plurality of parallel small cyclones. The three-stage cyclone end cover is threadedly connected to the two-stage cyclone base. The plurality of parallel small cyclones are mounted on the three-stage cyclone end cover and are evenly arranged around the long axis. Each small cyclone includes a spiral flow channel, a right-angle overflow pipe, and an inverted cone installed in a shell. The spiral flow channel is installed at the upper end of the shell. The inverted cone is installed at the lower port of the shell through an inverted cone support plate. The inverted cone support plate is provided with a three-stage bottom flow port. The lower port of the shell is inserted into the bottom flow hole of the bridge channel and is threadedly connected; the right-angle overflow pipe passes through the spiral flow channel and extends above the three-stage cyclone end cover; the annulus between the two-stage overflow channel and the shaft sleeve is the three-stage overflow channel, and the horizontal end of the right-angle overflow pipe is inserted into the three-stage overflow channel.

[0010] In the above scheme, the upper connecting shaft is connected to the long shaft through the upper coupling, and an upper protector is arranged outside the upper connecting shaft; the lower connecting shaft is connected to the lower centrifugal pump shaft, and a lower protector is arranged outside the lower connecting shaft.

[0011] In the above scheme, the upper end of the upper long outer sleeve is threadedly connected to the upper centrifugal pump housing, the lower end of the upper long outer sleeve is threadedly connected to the lower long outer sleeve, and the upper end of the upper centrifugal pump housing is threadedly connected to the upper end of the upper centrifugal pump.

[0012] In the above scheme, the upper end of the lower long outer sleeve is threadedly connected to the upper long outer sleeve, and the lower end of the lower long outer sleeve is threadedly connected to the lower centrifugal pump casing. Beneficial Effects

[0013] 1. The multi-stage series hydrocyclone assembly of the present invention has a shaft driven by a motor and runs through the entire multi-stage series hydrocyclone. The multi-stage series hydrocyclone can efficiently separate oil and water. A single motor is used to drive two centrifugal pumps to work. The upper collection and lower injection mode is adopted. The structure is simple and ingenious, and the operation difficulty is low.

[0014] 2. The multi-stage series hydrocyclone of the present invention is composed of three hydrocyclones with different structures connected in series. The multi-stage series design effectively improves the separation efficiency of the hydrocyclone, increases the oil field output and reduces the cost.

[0015] 3. The through-axis multi-stage hydrocyclone assembly of the present invention is placed in the middle of the pipe column, and the bearings at both ends can ensure the normal rotation of the long axis. The separated water phase flows in the annular space between the inner casing and the long outer casing, directly bypassing the motor and protector unit. On the one hand, it reduces the requirements for the insulation of the motor and the protector and reduces the manufacturing cost of the equipment. On the other hand, it also increases the service life of the equipment.

[0016] 4. The entire pipe column of the present invention is placed vertically underground, the liquid inlet hole is placed in the production layer, the lower centrifugal pump outlet is connected to the water injection layer, the upper downhole oil-water separation and production module, the downhole drive and reinjection module are distributed from top to bottom, and the shafts are connected together to run through the entire device, and synchronous rotation drives the device to operate during operation. The same-well injection and production device of this design has stable operation, good oil-water separation effect, high efficiency, and the single-motor design can effectively save costs. It has certain practicality and can ensure high oil production in oil fields with high water content.

[0017] 5. The present invention can complete the separation of oil-water mixture underground. The multi-stage series design makes it adaptable to different oil contents, improves the oil-water separation efficiency of the produced fluid, reduces the cost of lifting the produced fluid, and injects the separated water back to the ground, effectively saving mining costs and improving oil production efficiency. The same-well injection and production process designed by the present invention has an ingenious structure and low operating costs. It only needs one motor to work. It is a same-well injection and production device with practical value. The entire pipe string is driven by a single motor to rotate two centrifugal pumps, and a coupling is used to connect the shafts. The design of each bearing part ensures the normal rotation of the shaft and the normal operation of the centrifugal pump. It is a same-well injection and production pipe string suitable for use in high-water-content oil fields.

[0018] 6. The present invention comprises a downhole oil-water separation and production module and a downhole drive and reinjection module to form a same-well injection and production process string. The downhole oil-water separation and production module first performs downhole oil-water separation on the oil-water mixture, and the separated oil phase is subsequently pumped out to the ground by an upper centrifugal pump, and the separated water phase enters the downhole drive and reinjection module, is pumped out to the ground by a lower centrifugal pump, and is the power source of the entire device. A multi-stage series cyclone is used as the oil-water separation device. When the oil content of the produced fluid increases, the multi-stage series structure can improve the separation efficiency of the cyclone, so that more oil phase flows out from the overflow port of the cyclone, widens the cyclone diversion ratio, and increases the production efficiency of the same-well injection and production device. 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 It is an exploded view of the present invention.

[0021] Figure 3 (a) is the overall appearance of the downhole oil-water separation and production module; Figure 3 (b) is a cross-sectional view of the downhole oil-water separation and production module.

[0022] Figure 4 This is an exploded view of the downhole oil-water separation and production module.

[0023] Figure 5 This is a cross-sectional view of a multi-stage cyclone.

[0024] Figure 6 This is a cross-sectional view of the first-stage cyclone.

[0025] Figure 7 Cross-sectional view of the secondary cyclone and the tertiary cyclone.

[0026] Figure 8 (a) is the overall appearance of the downhole drive and reinjection module; Figure 8 (b) is a half-section view of the downhole drive and reinjection module.

[0027] Fig. 9 This is an exploded view of the downhole drive and reinjection module.

[0028] In the figure, 1-downhole oil-water separation and production module, 2-downhole drive and reinjection module, 101-upper long outer casing, 102-liquid inlet, 103-upper centrifugal pump housing, 104-upper centrifugal pump, 105-bearing installer, 106-long shaft, 107-multi-stage series cyclone, 108-first-stage cyclone, 109-second-stage cyclone, 110-third-stage cyclone, 119-bridge channel, 111-support sheet, 112-shaft sleeve, 1071-total overflow port, 1081-first-stage overflow port, 113-lining, 114-tangential inlet, 1082-first-stage bottom flow port, 1091-second-stage cyclone liquid inlet, 115-second-stage cyclone spiral flow channel, 1092-second-stage cyclone -level overflow port, 1093-secondary underflow port, 1094-secondary cyclone base, 1101-third-level cyclone liquid inlet, 1102-third-level overflow port, 1103-third-level cyclone end cover, 116-third-level cyclone spiral flow channel, 117-third-level cyclone inverted cone, 1104-third-level underflow port, 118-inverted cone support plate, 201-lower long outer sleeve, 202-lower centrifugal pump housing, 203-upper coupling, 204-upper protector, 205-motor, 206-lower protector, 207-lower coupling, 208-bearing cover, 209-lower centrifugal pump, 210-upper connecting shaft, 211-lower connecting shaft, 212-lower centrifugal pump shaft, 213-inner sleeve. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings: See also Figure 1-Figure 9The offshore oilfield double-pump suction widened diversion ratio high-processing capacity separation device comprises an underground oil-water separation and production module 1 and an underground drive and reinjection module 2. The underground oil-water separation and production module 1 comprises an upper long outer casing 101, an upper centrifugal pump 104, a bearing mounter 105, a long shaft 106, a shaft sleeve 112, and a multi-stage series cyclone. A liquid inlet hole 102 is arranged on the upper part of the upper long outer casing 101. The multi-stage series cyclone is arranged in the upper long outer casing 101. The upper end of the long shaft 106 passes through the bearing mounter and is connected to the upper centrifugal pump 104. The lower end of the long shaft passes through the multi-stage series cyclone 107 and the bridge channel 119 in sequence. The lower end of the long shaft passes through the bearing seat of the bridge channel and is connected to the upper connecting shaft of the underground drive and reinjection module 2. The upper end of the bearing installer 105 is pre-tightened with the upper centrifugal pump 104 by bolts. The bearing installer includes a mounting cylinder, the center of the mounting cylinder is a bearing chamber, the bearing chamber and the inner wall of the mounting cylinder are connected by an arc block, an arc cavity is provided between the bearing chamber and the mounting cylinder, the upper end cavity of the bearing chamber and the lower end cavity of the bearing chamber are communicated through the arc cavity, and an oil delivery channel is formed, and the oil delivery channel is communicated with the total overflow port of the multi-stage series cyclone 107; a shaft sleeve is provided at the center of the multi-stage series cyclone 107, and the shaft sleeve is provided outside the long axis; a long axis hole is provided at the top center of the bridge channel, and upper and lower flow holes are distributed around the long axis hole, the upper part of the bearing seat is located in the cavity, and the lower part of the bearing seat passes through the bottom of the bridge channel, the lower part of the bearing seat is provided with an external thread, and the bottom flow hole is provided at the bottom of the bridge channel, and the upper bottom flow hole, the cavity, and the lower bottom flow hole are communicated.

[0030] The downhole oil-water separation and production module 1 specifically includes: an upper long outer casing 101, a liquid inlet 102, an upper centrifugal pump housing 103, an upper centrifugal pump 104, a bearing mounter 105, a long shaft 106, a multi-stage series cyclone 107, a primary cyclone 108, a secondary cyclone 109, a tertiary cyclone 110, a bridge channel 119, a support sheet 111, a sleeve 112, a total overflow port 1071, a primary overflow port 1081, an inner liner 113, a tangential inlet 114, a primary underflow port 1082, a secondary cyclone liquid inlet 1091, a secondary cyclone spiral flow channel 115, a secondary overflow port 1092, a secondary underflow port 1093, a secondary cyclone Base 1094, three-stage cyclone liquid inlet 1101, three-stage cyclone end cover 1103, three-stage overflow port 1102, three-stage cyclone spiral flow channel 116, three-stage cyclone inverted cone 117, three-stage bottom flow port 1104, inverted cone support plate 118; upper long outer sleeve 101 is threadedly connected with upper centrifugal pump casing 103 and lower long outer sleeve 201 respectively, and a liquid inlet hole 102 is opened on the surface of the upper long outer sleeve 101. The upper end of the upper centrifugal pump casing 103 is threadedly connected with the upper end of the upper centrifugal pump 104, so that the upper centrifugal pump 104 is fixed above the injection and production pipe string in the same well. When the upper centrifugal pump 104 is working, the oil phase flowing into the total overflow port 1071 is sucked to the ground.

[0031] The long shaft 106 passes through the bearing installer 105 and is connected to the upper centrifugal pump 104, driving the upper centrifugal pump 104 to rotate; the upper end of the bearing installer 105 is pre-tightened with the lower end of the upper centrifugal pump 104 by bolts; the multi-stage cyclone 107 is installed inside the long outer sleeve 101, the upper end of the multi-stage cyclone 107 is close to the upper end boss of the long outer sleeve 101, and the lower end of the multi-stage cyclone 107 is inserted into the bridge channel 119.

[0032] The liquid inlet 102 and the tangential inlet 114 are located at the same horizontal line. The oil-water produced fluid passes through the liquid inlet 102 and enters the multi-stage cyclone 107 from the tangential inlet 112. The multi-stage cyclone 107 is composed of three cyclones connected in series: a primary cyclone 108, a secondary cyclone 109, and a tertiary cyclone 110. The two ends of the support sheet 111 are respectively connected to the side wall of the primary cyclone 108 and the shaft sleeve 113 to play a supporting role; the long shaft 106 runs through the interior of the multi-stage cyclone 107 and rotates in the shaft sleeve 113.

[0033] An inner liner 1081 is provided at the inlet of the first-stage cyclone 108. The side wall of the inner liner 1081 close to the cyclone shell is a conical structure and is connected to the inner wall of the first-stage cyclone 108 shell, so that the produced fluid entering from the tangential inlet 114 flows through the inner liner and moves downward in a spiral. The oil and water phases are separated due to different centrifugal forces due to their different densities. The separated oil phase flows into the total overflow port 1071 through the first-stage overflow port 1081, and the separated water phase flows into the liquid inlet 1091 of the second-stage cyclone through the first-stage bottom flow port 1082, followed by secondary separation.

[0034] The upper end of the secondary cyclone 109 is connected to the lower end of the primary cyclone 108 by threads, and the lower end of the spiral flow channel 115 of the secondary cyclone is threaded and threadedly connected to the inner wall of the secondary cyclone 109; the water phase separated by the primary cyclone 108 is tangentially rotated in the spiral flow channel 115 of the secondary cyclone for secondary separation, and the oil phase after the secondary separation flows into the total overflow port 1071 from the secondary overflow port 1092, and the separated water phase flows into the liquid inlet 1101 of the tertiary cyclone from the secondary bottom flow port 1093, and finally the tertiary separation is performed.

[0035] The tertiary cyclone 110 is formed by four small cyclones of the same structure connected in parallel. The upper end of the tertiary cyclone 110 is threadedly connected to the lower end of the tertiary cyclone end cover 1103, and the lower end of the tertiary cyclone 110 is inserted into the bridge channel 119; the tertiary overflow port 1102 is inserted into the spiral flow channel 116 of the tertiary cyclone, and the upper end of the tertiary cyclone end cover 1103 is threadedly connected to the lower end of the secondary cyclone base 1094; the water phase after secondary separation enters the secondary cyclone base 1094 and the tertiary cyclone end cover 1103. The oil phase after three separations flows into the total overflow port 1071 from the third-stage overflow port 1102, and the water phase flows into the porous structure of the bridge channel 119 from the third-stage bottom flow port 117, and finally flows into the downhole driving and reinjection module 2. The downhole drive and reinjection module 2 specifically includes a lower long outer sleeve 201, a lower centrifugal pump housing 202, an upper coupling 203, an upper protector 204, a motor 205, a lower protector 206, a lower coupling 207, a bearing cover 208, a lower centrifugal pump 209, an upper connecting shaft 210, a lower connecting shaft 211, a lower centrifugal pump shaft 212, and an inner sleeve 213; the upper end of the lower long outer sleeve 201 is threadedly connected to the upper long outer sleeve 101, and the lower end is provided with a thread for connecting with the lower centrifugal pump housing 202; the upper coupling 203 connects the long shaft 106 and the upper connecting shaft 210 together; the lower end of the multi-stage cyclone 107 has a thread connected to the internal thread of the bridge channel 119, and the water phase flowing out of the hole-shaped structure in the bridge channel 119 flows into the downhole drive and reinjection module 2; The upper connecting shaft 210 passes through the upper protector 204 and is fixed inside the upper protector 204; the shafts at both ends of the motor 205 pass through the upper protector 204 and the lower protector 206 respectively; the lower connecting shaft 211 passes through the lower protector 206 and is fixed inside the lower protector 206; the lower coupling 207 is used to connect the lower connecting shaft 211 with the pump shaft 212; the upper end of the inner sleeve 213 is threadedly connected to the lower thread of the bridge channel 119, and the lower end of the inner sleeve 213 is bolted to the bearing cover 208.

[0036] The inner sleeve 213 is located inside the lower long outer sleeve 201, with the upper end threadedly connected to the lower part of the bridge channel 119 and the lower end bolted to the bearing cover 208; the motor 205, the upper protector 204 and the lower protector 206 are placed together at the center of the inner sleeve 213; the upper connecting shaft 210 passes through the upper protector 204 and is connected to the long shaft 106 through the upper coupling 203.

[0037] The lower centrifugal pump shaft 212 passes through the lower centrifugal pump 209 to drive it to rotate; the lower centrifugal pump housing 202 is outside the lower centrifugal pump 209, and its upper end has a thread that is threadedly connected to the lower end of the lower long outer sleeve 201; the upper end of the lower long outer sleeve 201 is threadedly connected to the upper long outer sleeve 101, and the lower end is threadedly connected to the lower centrifugal pump housing 202; the lower connecting shaft 211 passes through the lower protector 206 and is connected to the pump shaft 212 through the lower coupling 207; the pump shaft 212 passes through the lower centrifugal pump 209 and is located outside the lower centrifugal pump The inside of the shell 202; after connection, an underflow channel is formed, which is the space area through which the separated aqueous phase medium flows from the underflow port 112 into the bridge channel 119 to the lower centrifugal pump 209. The path is as follows: the aqueous phase enters the bridge channel 119 from the underflow port 112 of the cyclone, flows from the inner peripheral hole 1193 of the bridge channel 119 into the annular space formed by the inner casing 213 and the lower long outer casing 201, avoids entering the inner casing 213, and then enters the lower centrifugal pump 209 and is injected back into the ground.

[0038] like Figure 1 As shown, the device is installed vertically underground and works. When working, the oil-water mixture enters the device from the liquid inlet 102. The upper end of the entire pipe string is connected to the ground device, and the lower end of the pipe string is connected to the reinjection layer. Figure 3 As shown, the upper centrifugal pump 104 is driven by the long shaft 106 to rotate and generate suction to extract the oil phase out of the pipe column. The bearing installer 105 has a bearing to ensure the stable rotation of the long shaft 106. When the device is working, the oil-water mixture fills the upper long outer sleeve 101 and the annular space outside the tangential inlet 114, and enters the multi-stage cyclone 107 at a certain speed, and then the oil and water are separated. After multiple separations, the water phase enters the bridge channel 119 from the third-stage bottom flow outlet 1104.

[0039] like Figure 5 As shown, after the produced liquid enters the multi-stage cyclone 107 at a certain speed from the tangential inlet 114, the produced liquid is first separated by the primary cyclone 108. The design of the liner 113 can accelerate the liquid rotation speed and improve the separation efficiency. The long shaft 106 passes through the multi-stage cyclone 107 and rotates inside the sleeve 113. The support sheet 114 connects the sleeve 113 and the inner wall of the multi-stage cyclone 107, so that the sleeve 113 is stabilized in the center of the multi-stage cyclone 107. Figure 6 and Figure 7 As shown, after the produced liquid passes through the primary cyclone 108 for initial separation, the separated water phase flows into the secondary cyclone 109 for further separation. The water phase after the secondary separation is finally separated for the last time by the tertiary cyclone 110 formed by four cyclones connected in parallel, and the oil phase after each stage of separation flows into the total overflow port 1071 from the overflow ports of each stage. After three separations, the water phase enters the bridge channel 119 from the bottom flow port 1071. There are small holes inside the bridge channel 119, and the water phase flows into the hollow part between the inner casing 213 and the lower long outer casing 201 from the small holes.

[0040] like Figure 8 As shown, the upper coupling 203 connects the long shaft 106 and the upper connecting shaft 210 so that they rotate together, the upper protector 204 and the lower protector 206 ensure the normal rotation of each shaft and the normal operation of the motor 205, the inner sleeve 213 surrounds the upper coupling 203, the upper protector 204, the motor 205, the lower protector 206, and the lower coupling 207, and the lower end of the inner sleeve 213 is connected to the bearing cover to ensure that no water enters the interior. The lower coupling 207 connects the lower connecting shaft 211 and the lower centrifugal pump shaft 212, and the pump shaft drives the lower centrifugal pump 209 to rotate, generating suction to inject the water phase back into the ground.

[0041] The same-well injection and production process designed by the present invention is reliable and stable in operation and is suitable for on-site work. The single-motor design can save costs, the multi-stage cyclone separation efficiency is high, and the upper-mining and lower-injection working mode greatly reduces the mining cost and pollution, and can also reduce the number of injection wells and production costs. The design of the same-well injection and production technology is suitable for working in oil fields with high water content and has high practicality.

Claims

1. An offshore oilfield dual-pump suction type widened split ratio high-capacity separation device, characterized in that: The offshore oilfield double pump suction widened split ratio high processing capacity separation device comprises a downhole oil-water separation and production module and a downhole drive and reinjection module, wherein the downhole oil-water separation and production module comprises an upper long outer casing, an upper centrifugal pump, a bearing mounter, a long shaft, a shaft sleeve, and a multi-stage series cyclone. A liquid inlet hole is arranged at the upper part of the upper long outer casing, and the multi-stage series cyclone is arranged in the upper long outer casing. The upper end of the long shaft passes through the bearing mounter and is connected to the upper centrifugal pump, and the lower end of the long shaft passes through the multi-stage series cyclone and the bridge channel in sequence. The lower end of the long shaft passes through the bearing seat of the bridge channel and is connected to the upper connecting shaft of the downhole drive and reinjection module. The upper end of the bearing installer is pre-tightened with the upper centrifugal pump by bolts. The bearing installer includes a mounting cylinder. The center of the mounting cylinder is a bearing chamber. The bearing chamber and the inner wall of the mounting cylinder are connected by an arc block. There is an arc cavity between the bearing chamber and the mounting cylinder. The upper cavity of the bearing chamber and the lower cavity of the bearing chamber are connected through the arc cavity to form an oil delivery channel. The oil delivery channel is connected to the total overflow port of the multi-stage series cyclone. A shaft sleeve is arranged at the center of the multi-stage series cyclone, and the shaft sleeve is arranged outside the long axis. A long axis hole is arranged at the top center of the bridge channel, and upper and lower flow holes are distributed around the long axis hole. The upper part of the bearing seat is located in the cavity, and the lower part of the bearing seat passes through the bottom of the bridge channel. The lower part of the bearing seat is provided with an external thread, and the bottom flow hole is arranged at the bottom of the bridge channel. The upper bottom flow hole, the cavity, and the lower bottom flow hole are connected. The downhole drive and reinjection module includes an upper connecting shaft, a motor, a lower connecting shaft and a lower centrifugal pump. The inner casing is coaxially arranged in the lower long outer casing. The upper connecting shaft, the motor and the lower connecting shaft connected in sequence are arranged in the inner casing. The lower connecting shaft is connected to the lower centrifugal pump. The annular space between the inner casing and the lower long outer casing is a diversion channel, and the lower bottom flow hole of the bridge channel is connected to the diversion channel.

2. The offshore oilfield dual-pump suction type widened split ratio high-processing capacity separation device according to claim 1 is characterized in that: The multi-stage series cyclone is composed of three cyclones connected in series: a primary cyclone, a secondary cyclone and a tertiary cyclone.

3. The offshore oilfield dual-pump suction type widened split ratio high-processing capacity separation device according to claim 2 is characterized in that: The primary cyclone comprises a primary shell, a sleeve and a primary overflow pipe. The primary shell is composed of a total overflow cylinder arranged at the upper end of a primary cone. The sleeve is centrally arranged in the primary cone. The outer edge of the upper port of the sleeve is fixedly connected to the inner wall of the primary shell through a support sheet. A total overflow port is arranged between the support sheet and the upper port of the primary shell. The lower port of the sleeve is located in the primary cone and is provided with an inner liner. The outer wall of the lower port of the inner liner is a conical structure. The primary overflow pipe is coaxially arranged outside the sleeve. The pipe mouth of the primary overflow pipe is fixed in the total overflow cylinder through an eccentric fixing ring. The eccentric fixing ring and the inner wall of the total overflow cylinder have a primary overflow port. The upper port of the annulus between the primary overflow pipe and the sleeve is communicated with the total overflow cylinder. An annular hole is provided between the primary overflow pipe and the inner liner. A tangential inlet is arranged near the lower port of the inner liner at the primary cone. The tangential inlet is arranged corresponding to the liquid inlet. An outer step is arranged on the outer wall of the primary cone. The annular port between the lower port of the primary cone and the lower port of the primary overflow pipe is a primary underflow port.

4. The offshore oilfield dual-pump suction type widened split ratio high-processing capacity separation device according to claim 3 is characterized in that: The secondary cyclone comprises a secondary shell, a spiral flow channel, and a secondary overflow pipe. The primary overflow pipe extends downward to the straight section of the secondary shell and forms a spiral flow channel on the outer wall. The secondary overflow pipe is coaxially arranged between the shaft sleeve and the primary overflow pipe. The annular space between the secondary overflow pipe and the primary overflow pipe is a secondary overflow channel. The upper port of the secondary overflow channel is communicated with the main overflow cylinder, and the lower port of the secondary overflow channel is a secondary overflow port. The bottom of the secondary shell is a secondary cyclone base, and the lower inlet of the annular cavity between the secondary shell and the secondary overflow pipe is a secondary bottom flow port.

5. The offshore oilfield dual-pump suction type widened split ratio high-processing capacity separation device according to claim 4, characterized in that: The three-stage cyclone comprises a three-stage cyclone end cover and a plurality of parallel small cyclones. The three-stage cyclone end cover is threadedly connected to the two-stage cyclone base. The plurality of parallel small cyclones are mounted on the three-stage cyclone end cover and are evenly arranged around the long axis. Each small cyclone comprises a spiral flow channel, a right-angle overflow pipe and an inverted cone installed in a shell. The spiral flow channel is mounted on the upper end of the shell. The inverted cone is mounted on the lower port of the shell through an inverted cone support plate. The inverted cone support plate is provided with a three-stage bottom flow port. The lower port of the shell is inserted into the bottom flow hole of the bridge channel and is threadedly connected. The right-angle overflow pipe passes through the spiral flow channel and extends above the three-stage cyclone end cover. The annulus between the two-stage overflow channel and the shaft sleeve is a three-stage overflow channel. The horizontal end of the right-angle overflow pipe is inserted into the three-stage overflow channel.

6. The offshore oilfield double pump suction type widened diversion ratio high processing capacity separation device according to claim 5, characterized in that: The upper connecting shaft is connected to the long shaft through an upper coupling, and an upper protector is arranged outside the upper connecting shaft; the lower connecting shaft is connected to the lower centrifugal pump shaft, and a lower protector is arranged outside the lower connecting shaft.

7. The offshore oilfield double pump suction type widened diversion ratio high processing capacity separation device according to claim 6, characterized in that: The upper end of the upper long outer sleeve is threadedly connected to the upper centrifugal pump housing, the lower end of the upper long outer sleeve is threadedly connected to the lower long outer sleeve, and the upper end of the upper centrifugal pump housing is threadedly connected to the upper end of the upper centrifugal pump.

8. The offshore oilfield dual-pump suction type widened diversion ratio high-processing capacity separation device according to claim 7, characterized in that: The upper end of the lower long outer sleeve is threadedly connected to the upper long outer sleeve, and the lower end of the lower long outer sleeve is threadedly connected to the lower centrifugal pump housing.

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