Injection of oil and water separation device

Abstract

The application discloses an oil-water separation device for simultaneous injection in a well, and belongs to the technical field of oilfield exploitation. The device comprises a shell, a partition plate, an inner cylinder and a sealing part. The shell is provided with a hollow cavity and a plurality of liquid inlets. The partition plate is located below the liquid inlets and separates the bottom of the hollow cavity into a water collecting chamber. The inner cylinder is connected to the center of the partition plate and is provided with a first flow channel and a second flow channel. The first flow channel is communicated with the water collecting chamber and the inner diameter thereof gradually expands towards the second flow channel. The second flow channel is in a columnar shape. The horizontal plate of the sealing part is adjustably arranged in the hollow cavity in an axial direction and separates the cavity above the partition plate into a flow regulating chamber and an oil collecting chamber. A columnar section is coaxially connected to the horizontal plate and is inserted into the second flow channel. Spiral blades are correspondingly connected to the bottom of straight blades and both are arranged on the outer wall surface of the columnar section in a circumferential direction and are attached to the inner wall of the second flow channel. A conical section is connected to the columnar section and can be inserted into the first flow channel. The sealing part is provided with an oil guiding channel which is communicated with the oil collecting chamber and the first flow channel. The application widens the operation window and improves the separation stability.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, and in particular to an oil-water separation device for simultaneous well injection. Background Technology

[0002] The proliferation of high water-cut wells presents a dual challenge to oilfield production. On one hand, high water cut leads to a significant increase in energy consumption during lifting, gathering, and wastewater treatment, resulting in a sharp rise in infrastructure costs and directly causing increased production costs and decreased profitability. Some wells are already facing closure due to low extraction efficiency. On the other hand, wastewater treatment requires the extensive use of chemical reagents, which can easily cause environmental pollution problems in water bodies and soil, further intensifying the environmental pressure on oilfield development.

[0003] Solving the challenges of exploiting and treating high water-cut oil wells has become crucial for ensuring the sustainable development of oil fields.

[0004] To address the dual pressures of production costs and environmental impact posed by high water-cut oil wells, engineers proposed a downhole separation and simultaneous injection-production solution. The core of this solution is to directly separate oil and water inside the wellbore, reinjecting the separated water directly into underground abandoned or water-injection layers. The separated crude oil and a small amount of associated water are then transported to the surface via a lifting device. This allows for simultaneous water injection and oil production operations within a single well, effectively reducing surface water production, lowering surface processing load and production costs, and providing a feasible path for the efficient exploitation of high water-cut oil wells.

[0005] However, most hydrocyclones currently used in downhole oil-water separators have a single-sided tangential inlet structure. This structure has poor internal flow field stability and large turbulent dissipation, resulting in a narrow operating window that can only maintain separation efficiency under fixed conditions. However, key parameters such as the flow rate and oil content of the produced fluid in oilfield wellbores are often in a state of dynamic fluctuation. The narrow operating window simply cannot adapt to such complex and variable actual conditions, easily leading to problems such as a sharp drop in separation efficiency and substandard water quality.

[0006] Therefore, there is an urgent need to develop an oil-water separation device for simultaneous well injection to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide an oil-water separation device that can be used in the same well injection process, adapt to the fluctuating conditions of high water cut produced fluid in downhole, broaden the operating window, and improve separation stability.

[0008] Based on the above concept, the technical solution adopted by this invention is as follows:

[0009] A method for using an oil-water separation device in well injection, which is vertically lowered into the well along with the tubing string, includes:

[0010] The outer shell has a hollow cavity extending along the axial direction, and a plurality of liquid inlets spaced apart along a first direction and connected to the hollow cavity;

[0011] A partition, located below all the liquid inlets and connected to the inner wall of the hollow cavity, separates the bottom of the hollow cavity into a water collection chamber;

[0012] The inner cylinder has one end connected to the center of the partition and the other end extending away from the water collection chamber. The inner cylinder has a first flow channel and a second flow channel that are connected through it along the axial direction. The first flow channel is directly connected to the water collection chamber and its inner diameter gradually increases towards the second flow channel. The second flow channel is cylindrical.

[0013] The packer includes a horizontal plate, a cylindrical section, a conical section, multiple straight blades, and multiple helical blades. The horizontal plate is axially adjustable within the hollow cavity and divides the cavity above the partition into a rectifier chamber and an oil collecting chamber located above the rectifier chamber. The cylindrical section is coaxially connected to the horizontal plate and inserted into the second flow channel. The multiple helical blades are connected one-to-one to the bottom of the multiple straight blades, and both the straight blades and the helical blades are circumferentially spaced on the outer wall of the cylindrical section and abut against the inner wall of the second flow channel. The conical section is connected to the bottom of the cylindrical section and can extend into the first flow channel. The packer has an axially penetrating oil guide channel connecting the oil collecting chamber and the first flow channel.

[0014] Furthermore, the inner cylinder includes a column and a cone, the cone is connected to the partition, and the outer wall surface of the cone gradually moves away from the central axis of the cone in a direction away from the partition until it connects to the outer surface of the column.

[0015] Furthermore, the cone includes a first cone segment and a second cone segment. The first cone segment is connected to the partition and its outer diameter gradually increases in the direction away from the partition. The second cone segment is connected to the first cone segment, and the outer wall surface of the second cone segment and the outer wall surface of the first cone segment are set at an angle.

[0016] Furthermore, the angle between the outer wall surface of the second conical segment and the outer wall surface of the first conical segment is 15° to 30°.

[0017] Furthermore, the first flow channel includes a first flow section and a second flow section, the first flow section is directly connected to the water collection chamber, and the inner wall of the second flow section and the inner wall of the first flow section are arranged at an angle.

[0018] Furthermore, the cone angle formed by the inner wall of the second flow section and the cone angle formed by the outer wall of the conical section differ by no more than 5°.

[0019] Furthermore, the sealing member also includes a plurality of streamlined blades, the straight blades and the helical blades being connected through the streamlined blades, and the streamlined blades being tangent to both the straight blades and the helical blades.

[0020] Furthermore, the tilt angle of the helical blade is 25°-30°.

[0021] Furthermore, the oil-water separation device for same-well injection also includes a fixing ring, which is threadedly connected to the inner wall of the outer shell, the cylindrical section passes through the fixing ring, and the horizontal plate is detachably connected to the top surface of the fixing ring.

[0022] Furthermore, a sealing ring is sandwiched between the cross plate and the fixing ring.

[0023] The beneficial effects of this invention are:

[0024] This invention proposes an oil-water separation device for in-well injection. By controlling the fluid flow field three times, it solves the problems of unstable flow field, large turbulent dissipation, and narrow operating window in existing downhole separation equipment, while achieving efficient oil-water separation. First, multiple inlets spaced at intervals along the first direction on the outer shell uniformly introduce the produced fluid, allowing it to smoothly enter the hollow cavity. This avoids the impact disturbance caused by single-sided tangential inlet injection, weakening fluid turbulence from the source and improving the uniformity and stability of the flow field. Second, straight blades and helical blades on the packer sequentially regulate and guide the fluid entering the second flow channel of the inner cylinder. The straight blades first distribute the fluid circumferentially and stabilize it axially, reducing fluid disturbance and disordered pulsation, making the flow field more uniform and stable. Then, the helical blades provide controllable swirl for the stable fluid, causing it to form a stable rotating flow. Under the action of centrifugal force and oil-water density difference, efficient pre-separation is achieved, ensuring centrifugal separation power while reducing turbulent dissipation. Finally, by adjusting the position of the transverse plate along the axial direction, the flow area of ​​the annular regulating cavity formed by the conical section and the inner wall of the first flow channel can be flexibly adjusted, so that the fluid can obtain a suitable intensity of rotational kinetic energy, thereby adapting to the complex working conditions of dynamic fluctuations in flow rate and oil content in the wellbore, widening the operating window of the device, and ensuring stable separation efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the oil-water separation device used in the same well injection according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the sealing member provided in an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the inner cylinder provided in an embodiment of the present invention.

[0028] In the picture:

[0029] 1. Outer shell; 11. Liquid inlet; 101. Water collection chamber; 102. Rectifying chamber; 103. Oil collection chamber;

[0030] 2. Partition;

[0031] 3. Inner cylinder; 31. Column; 32. Cone; 321. First conical section; 322. Second conical section; 301. First flow channel; 3011. First flow section; 3012. Second flow section; 302. Second flow channel;

[0032] 4. Packer; 40. Oil guide channel; 41. Horizontal plate; 42. Cylindrical section; 43. Conical section; 44. Straight blade; 45. Helical blade; 46. Streamlined blade;

[0033] 5. Fixing ring. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0035] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0038] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0039] like Figures 1 to 3 As shown, this invention provides an oil-water separation device for in-well injection, which is vertically lowered into the well along with the tubing string. It includes an outer shell 1, a partition 2, an inner cylinder 3, and a packer 4. The outer shell 1 has an axially extending hollow cavity and multiple inlets 11 spaced apart along a first direction and connected to the hollow cavity. The partition 2 is located below all the inlets 11 and connected to the inner wall of the hollow cavity, separating a water collection chamber 101 at the bottom of the hollow cavity. One end of the inner cylinder 3 is connected to the center of the partition 2, and the other end extends away from the water collection chamber 101. The inner cylinder 3 has a first flow channel 301 and a second flow channel 302 connected sequentially along the axial direction. The first flow channel 301 is directly connected to the water collection chamber 101 and its inner diameter gradually increases towards the second flow channel 302, which is cylindrical. The packer 4 includes... The system comprises a horizontal plate 41, a cylindrical section 42, a conical section 43, multiple straight blades 44, and multiple helical blades 45. The horizontal plate 41 is axially adjustable within the hollow cavity, dividing the cavity above the partition 2 into a rectifier chamber 102 and an oil collecting chamber 103 located above the rectifier chamber 102. The cylindrical section 42 is coaxially connected to the horizontal plate 41 and inserted into the second flow channel 302. The multiple helical blades 45 are correspondingly connected to the bottom of the multiple straight blades 44, and both the straight blades 44 and the helical blades 45 are circumferentially spaced on the outer wall of the cylindrical section 42 and abut against the inner wall of the second flow channel 302. The conical section 43 is connected to the bottom of the cylindrical section 42 and can extend into the first flow channel 301. The sealing member 4 has an axially penetrating oil guide channel 40 connecting the oil collecting chamber 103 and the first flow channel 301. The first direction can be either circumferential or axial along the outer shell 1.

[0040] This invention solves the problems of unstable flow field, large turbulent dissipation, and narrow operating window in existing downhole separation equipment by regulating the fluid flow field in three stages, while achieving efficient oil-water separation. First, multiple inlets 11 spaced apart along the first direction on the outer shell 1 uniformly introduce the produced fluid, allowing it to smoothly enter the hollow cavity. This avoids the impact disturbance caused by traditional tangential inlet single-sided injection, weakening fluid turbulence from the source and improving the uniformity and stability of the flow field. Second, the straight blades 44 and helical blades 45 on the packer 4 sequentially regulate and guide the fluid entering the second flow channel 302 of the inner cylinder 3. The straight blades 44 first distribute the fluid circumferentially and stabilize it axially, weakening fluid disturbance and disordered pulsation, making the flow field more uniform and stable. Then, the helical blades 45 provide controllable swirl for the stable fluid, causing the fluid to form a stable rotating flow. Under the action of centrifugal force and oil-water density difference, efficient pre-separation is achieved, ensuring centrifugal separation power while reducing turbulent dissipation. Finally, by adjusting the position of the transverse plate 41 along the axial direction, the flow area of ​​the annular regulating cavity formed by the conical section 43 and the inner wall of the first flow channel 301 can be flexibly adjusted, so that the fluid can obtain a suitable intensity of rotational kinetic energy, thereby adapting to the complex working conditions of dynamic fluctuations in flow rate and oil content in the wellbore, widening the operating window of the device, and ensuring stable separation efficiency.

[0041] The separated aqueous phase settles into the water collection chamber 101 through the first flow channel 301; the separated oil phase is transported upward to the oil collection chamber 103 through the oil guide channel 40 in the packer 4, thereby realizing in-situ downhole oil-water separation and co-well injection and production. In this embodiment, an oil guide pipe can be installed in the oil guide channel 40 so that the separated oil phase is transported upward to the oil collection chamber 103 through the oil guide pipe.

[0042] like Figure 1 As shown, specifically, the inlet 11 is a rectangular hole extending along the axial direction of the outer shell 1. The rectangular hole increases the inlet flow area, ensuring that the high water-cut produced fluid enters the hollow cavity smoothly and steadily, avoiding impact disturbances caused by sudden changes in flow velocity, and further improving the uniformity and stability of the flow field. Simultaneously, this hole shape is easy to process, and the hole wall experiences uniform stress, enabling it to withstand the impact of downhole produced fluid and extending its service life. The number of inlets 11 can be flexibly set according to actual needs and is not specifically limited here.

[0043] Specifically, the partition 2 is welded to the inner wall of the outer shell 1. The welding method provides high connection strength and reliable sealing, and can effectively withstand downhole fluid pressure and impact loads.

[0044] Specifically, such as Figure 1 and Figure 3As shown, the inner cylinder 3 includes a column 31 and a cone 32. The outer wall of the cone 32 gradually moves away from the central axis of the cone 32 in a direction away from the partition 2 until it connects to the outer surface of the column 31. This structure causes the flow cross section formed between the cone 32 of the inner cylinder 3 and the outer shell 1 to gradually decrease in a direction away from the liquid inlet 11. This allows the oil-water mixture entering the rectifier chamber 102 to gradually increase and continuously improve its flow velocity on the basis of uniform circumferential mixing, forming a gradually increasing push flow. This provides sufficient power for the subsequent flow stabilization by the straight blade 44, the swirling guidance by the spiral blade 45, and centrifugal separation.

[0045] In this embodiment, the second flow channel 302 is cylindrical and correspondingly opened inside the column 31.

[0046] More specifically, the cone 32 includes a first cone segment 321 and a second cone segment 322. The first cone segment 321 is connected to the partition 2 and its outer diameter gradually increases in the direction away from the partition 2. The second cone segment 322 is connected to the first cone segment 321, and the outer wall surface of the second cone segment 322 and the outer wall surface of the first cone segment 321 are set at an angle. The outer diameter of the second cone segment 322 gradually increases in the direction away from the first cone segment 321 until it connects to the column 31. The expansion angle of the second cone segment 322 is greater than that of the first cone segment 321, so that the flow cross section formed between the cone 32 of the inner cylinder 3 and the outer shell 1 exhibits a trend of first slowly contracting and then rapidly and sharply contracting. This abrupt contraction of the cross section can produce a significant acceleration and stabilization effect on the fluid, so that the fluid is rapidly pressurized and accelerated before entering the swirling separation region, further enhancing the swirling intensity.

[0047] More specifically, the angle between the outer wall of the second conical section 322 and the outer wall of the first conical section 321 is 15° to 30°. This angle difference range allows for a significant gradient contraction of the flow cross-section, enabling rapid and stable pressurization and acceleration of the fluid before it enters the swirling region, effectively improving the swirling intensity and centrifugal separation effect. At the same time, the 15° to 30° angle difference ensures sufficient fluid acceleration while avoiding the formation of violent eddies, a sharp increase in flow resistance, or flow field distortion caused by an excessively large angle difference. This significantly improves separation efficiency while ensuring stable operation of the device.

[0048] In this embodiment, the first conical segment 321 is inserted into a hole located at the center of the partition 2 and is sealed to the partition 2 by a sealing element or welding. The sealing element can be a sealing ring, a sealing gasket, or a combined sealing structure to ensure the sealing of the connection between the first conical segment 321 and the partition 2, preventing fluid from flowing through the mating gap.

[0049] Specifically, such as Figure 1As shown, the first flow channel 301 includes a first flow section 3011 and a second flow section 3012. The first flow section 3011 is directly connected to the water collection chamber 101, and the inner wall of the second flow section 3012 is set at an angle to the inner wall of the first flow section 3011. The water phase, after being pre-separated by the spiral blades 45, will enter the second flow section 3012 along the second flow channel 302. Due to the angle between the inner walls of the two flow sections, the flow direction and velocity of the water phase can be changed, avoiding the water phase from generating eddies or stagnation due to inertia, reducing turbulent dissipation, and preventing the turbulent flow of the water phase from interfering with the oil-water interface.

[0050] In this embodiment, the first flow segment 3011 is correspondingly opened within the first conical segment 321, and the second flow segment 3012 is correspondingly opened within the second conical segment 322. The cone angles of the first conical segment 321 and the second conical segment 322 are the same as the cone angles of the corresponding flow segments.

[0051] In this embodiment, the tapered segment 43 can be inserted into the second flow segment 3012 and form an annular adjustment cavity between it and the inner wall of the second flow segment 3012.

[0052] Specifically, the cone angle formed by the inner wall of the second flow section 3012 and the cone angle formed by the outer wall of the conical section 43 differ by no more than 5°. By controlling the difference in the apex angles of the two conical structures to within 5°, the inclination angle and expansion trend of the inner wall of the second flow section 3012 and the outer wall of the conical section 43 are highly consistent, forming a uniform and smooth annular flow channel between them. This avoids abrupt changes in local flow area, eddies, turbulence, and jet phenomena caused by excessive cone angle differences, reduces energy dissipation of the fluid during flow, and fully retains and utilizes the rotational kinetic energy of the fluid, thereby ensuring stable swirling intensity, reliable separation effect, and improving the adaptability and separation efficiency of the device under different operating conditions.

[0053] Specifically, such as Figure 1 As shown, the packer 4 also includes multiple streamlined blades 46. Straight blades 44 and helical blades 45 are connected by the streamlined blades 46, and the streamlined blades 46 are tangent to both the straight blades 44 and the helical blades 45. The tangential connection between the straight blades 44 and the helical blades 45 via the streamlined blades 46 creates a continuous and smooth transition surface for the entire blade assembly, eliminating sharp angles and abrupt changes in cross-section at the connection point. During the transition from the thrust flow in the region of the straight blades 44 to the rotational flow in the region of the helical blades 45, the fluid can smoothly change direction along the smooth surface, avoiding local eddies, flow separation, and impact losses caused by structural abrupt changes, reducing hydraulic losses, and thus making the transition from thrust flow to rotational flow more continuous and efficient, fully ensuring the effective establishment and utilization of the fluid's rotational kinetic energy.

[0054] Specifically, the tilt angle of the helical blades 45° is 25°-30°. This angle balances the swirling intensity and turbulent dissipation, creating a suitable rotating flow for efficient centrifugal separation while avoiding energy waste or incomplete separation caused by an improper angle. See also Figure 2 The angle α between the tangent of the straight blade 44 and the horizontal line is 90°, and β is the tilt angle of the helical blade 45, that is, the angle between the tangent of the helical blade 45 and the horizontal line.

[0055] Specifically, such as Figure 1 As shown, the oil-water separation device used in the same well injection also includes a fixed ring 5. The fixed ring 5 is connected to the inner wall of the outer shell 1 by a thread. The cylindrical section 42 passes through the fixed ring 5, and the horizontal plate 41 is detachably connected to the top surface of the fixed ring 5.

[0056] The inclusion of the fixing ring 5 avoids directly machining the adjustment structure on the outer wall of the slender cylindrical section 42, reducing the machining difficulty and dimensional tolerance control requirements of the packer 4. The horizontal plate 41 and the fixing ring 5 are detachably connected, facilitating device assembly and debugging, and allowing for individual disassembly and replacement of the packer components, improving the maintainability of the device. The fixing ring 5 is threaded to the inner wall of the outer shell 1, allowing continuous axial position adjustment by rotating the fixing ring 5, thereby driving the packer 4 to rise and fall as a whole, flexibly adjusting the swirling intensity and fluid flow area to adapt to separation requirements under different operating conditions. Furthermore, this threaded connection method provides accurate positioning, reliable load bearing, and good sealing performance, ensuring long-term stable operation of the device.

[0057] In this embodiment, the horizontal plate 41 is connected to the fixing ring 5 by bolts.

[0058] In other embodiments, the horizontal plate 41 and the fixing ring 5 can also be connected by a snap-fit ​​method.

[0059] More specifically, in order to increase the sealing between the horizontal plate 41 and the fixing ring 5, a sealing ring can be added between their mating surfaces to prevent fluid cross-flow between the rectifier chamber 102 and the oil collecting chamber 103, thereby further improving the chamber isolation effect and separation stability.

[0060] Experimental tests were conducted using this embodiment within the range of fluctuations in the produced fluid conditions of a certain well. The results show that, compared with traditional downhole separation equipment, the operating window of this embodiment is significantly widened, and the efficient separation range is expanded from 25% to 35% to 20% to 50%. For specific data, please refer to Table 1.

[0061] Under conditions of varying influent flow rate and a stable water content of around 95%, the oil-water separation device of this invention can maintain stable and efficient separation within a separation ratio range of 20% to 50%, with a separation efficiency of over 98.5% and stable and reliable effluent quality.

[0062]

[0063] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for injecting oil and water using a separation device, which is vertically lowered into the well along with the tubing string, characterized in that... include: The outer shell (1) has a hollow cavity extending along the axial direction, and a plurality of liquid inlets (11) spaced apart along a first direction and connected to the hollow cavity. The liquid inlets (11) are rectangular holes extending along the axial direction of the outer shell (1). A partition (2) is located below all the liquid inlets (11) and connected to the inner wall of the hollow cavity, separating the bottom of the hollow cavity into a water collection chamber (101). The inner cylinder (3) is connected at one end to the center of the partition (2) and extends away from the water collection chamber (101) at the other end. The inner cylinder (3) is axially perforated with a first flow channel (301) and a second flow channel (302). The first flow channel (301) is directly connected to the water collection chamber (101) and its inner diameter gradually increases toward the second flow channel (302). The second flow channel (302) is cylindrical. The sealing component (4) includes a horizontal plate (41), a cylindrical section (42), a conical section (43), multiple straight blades (44), and multiple helical blades (45). The horizontal plate (41) is axially adjustable within the hollow cavity and divides the cavity above the partition plate (2) into a rectifier chamber (102) and an oil collecting chamber (103) located above the rectifier chamber (102). The cylindrical section (42) is coaxially connected to the horizontal plate (41) and inserted into the second flow channel (302). The multiple helical blades (45) 45) The straight blades (44) are connected to the bottom of the multiple straight blades (44) in a one-to-one correspondence, and the straight blades (44) and the spiral blades (45) are all circumferentially spaced on the outer wall of the cylindrical section (42) and abut against the inner wall of the second flow channel (302). The conical section (43) is connected to the bottom end of the cylindrical section (42) and can extend into the first flow channel (301). The sealing member (4) is axially penetrated and has an oil guide channel (40) that connects the oil collection chamber (103) and the first flow channel (301). The oil-water separation device for well injection also includes a fixed ring (5), which is connected to the inner wall of the outer shell (1) by a thread. The cylindrical section (42) passes through the fixed ring (5), and the horizontal plate (41) is detachably connected to the top surface of the fixed ring (5). A sealing ring is sandwiched between the horizontal plate (41) and the fixed ring (5). The first flow channel (301) includes a first flow section (3011) and a second flow section (3012). The first flow section (3011) is directly connected to the water collection chamber (101). The inner wall of the second flow section (3012) and the inner wall of the first flow section (3011) are arranged at an angle. The cone angle formed by the inner wall of the second flow section (3012) and the cone angle formed by the outer wall of the cone section (43) differ by no more than 5°.

2. The oil-water separation device for same-well injection according to claim 1, characterized in that, The inner cylinder (3) includes a column (31) and a cone (32), the cone (32) is connected to the partition (2), and the outer wall surface of the cone (32) gradually moves away from the central axis of the cone (32) in a direction away from the partition (2) until it is connected to the outer surface of the column (31).

3. The oil-water separation device for same-well injection according to claim 2, characterized in that, The cone (32) includes a first cone segment (321) and a second cone segment (322). The first cone segment (321) is connected to the partition (2) and its outer diameter gradually increases in the direction away from the partition (2). The second cone segment (322) is connected to the first cone segment (321), and the outer wall surface of the second cone segment (322) and the outer wall surface of the first cone segment (321) are set at an angle.

4. The oil-water separation device for same-well injection according to claim 3, characterized in that, The angle between the outer wall of the second cone segment (322) and the outer wall of the first cone segment (321) is 15° to 30°.

5. The oil-water separation device for same-well injection according to claim 1, characterized in that, The sealing element (4) also includes a plurality of streamlined blades (46), the straight blades (44) and the helical blades (45) are connected by the streamlined blades (46), and the streamlined blades (46) are tangent to both the straight blades (44) and the helical blades (45).

6. The oil-water separation device for same-well injection according to claim 1, characterized in that, The tilt angle of the helical blade (45) is 25° to 30°.

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