An underground oil-water separation method, device and injection-production system

Abstract

An underground oil-water separation method, device and injection-production system. It mainly solves the problem that the underground hydrocyclone separator used in the existing underground co-well injection-production process system is difficult to adapt to the working conditions of ultra-large processing capacity. The characteristics are as follows: In an underground planar area, a hydrocyclone separation modular kit is set up, and each hydrocyclone separation kit contains at least two sets of hydrocyclone separation units with the same structure; the at least two sets of hydrocyclone separation units can evenly distribute the oil-water mixed-phase medium flowing through this planar area and carry out oil-water hydrocyclone separation treatment; the hydrocyclone separation modular kit has a common oil channel and a common water channel, the common oil channel can receive the oil phase separated from each hydrocyclone separation unit and transport it to the oil-phase inlet end of the lifting pump in the co-well injection-production well, and the common water channel can receive the water phase separated from each hydrocyclone separation unit and transport it to the water-phase inlet end of the reinjection pump in the co-well injection-production well.

Description

Technical Field

[0001] The present disclosure relates to a downhole oil-water separation method, device, and co-well injection-production in the field of co-well injection-production. Background Art

[0002] With the continuous exploitation of oil fields, most oil fields in China have entered the middle and late stages of development. The water cut of oil fields has gradually increased, and the water cut of many oil fields has reached more than 98%. With the development of downhole oil-water separation technology in co-well injection-production systems, more and more hydrocyclone separators have been applied to the downhole oil-water separation process of co-well injection-production. For example, the content disclosed in the patent with publication number CN11608638B, titled "Downhole Oil-Water Separation Co-Well Injection-Production Device and Method Driven by a Single Motor with Two Pumps". Hydrocyclone separators have the advantages of strong adaptability, simple structure, small volume, convenient loading and unloading, efficient and flexible separation, simple process, and continuous operation. However, after being applied downhole, the following problems have been found: Existing downhole hydrocyclone separators can complete the oil-water separation work within the range of their normal treatable liquid inflow. However, once the liquid production volume of the oil well is too large and the inflow volume exceeds the processing range of the downhole hydrocyclone separator, for example, in a specific working condition of 800 m³ / h, oil droplet emulsification will occur due to the excessive flow rate, resulting in a reduction in the oil-water separation efficiency. The same practical technical problems have occurred in large-scale offshore co-well injection-production systems with large drainage volumes.

[0003] Since the space inside the casing downhole is limited, unlike the situation of oil-water separation on the ground where the problem of excessive liquid inflow can be directly solved by paralleling several hydrocyclone separators, it is necessary to find a new oil-water separation method and device applicable to high liquid production volumes in the co-well injection-production wellbore. Summary of the Invention

[0004] To solve the technical problems mentioned in the background art, the present disclosure provides a downhole oil-water separation method, device, and injection-production system. After application, it can be applicable to both offshore and onshore environments in co-well injection-production systems with large drainage treatment volumes, ensuring effective separation of oil and water phases downhole, completing the downhole reinjection of the water phase while lifting the oil phase, and saving development costs.

[0005] The technical solution of the present invention is as follows:

[0006] First, a downhole oil-water separation method for a co-well injection-production well is given as a basic method, including the following steps:

[0007] In a limited space corresponding to the size of the downhole tubing, in a planar area, set: a hydrocyclone separation modular kit, and each hydrocyclone separation modular kit contains at least two sets of hydrocyclone separation units with the same structure;

[0008] At least two groups of the swirl separation units can evenly divide the oil-water mixed-phase medium flowing through this planar area and perform oil-water swirl separation treatment;

[0009] The swirl separation modular kit has a common oil channel and a common water channel. The common oil channel can receive the oil phase separated from each swirl separation unit and convey it to the oil-phase inlet end of the lifting pump in the same-well injection-production well, and the common water channel can receive the water phase separated from each swirl separation unit and convey it to the water-phase inlet end of the reinjection pump in the same-well injection-production well.

[0010] Based on the above basic method, the optimization method is as follows:

[0011] Vertically along the oil well, at least two swirl separation modular kits are arranged in adjacent different planar areas, and sealed connection can be achieved between adjacent swirl separation modular kits; the common oil channel and the common water channel between the swirl separation modular kits can be connected.

[0012] Through the optimization method, the swirl separation modular kits can be increased as needed to improve the liquid treatment volume of the same-well injection-production system.

[0013] To implement the above method, the present disclosure provides the following downhole oil-water separation device for a same-well injection-production well:

[0014] Solution 1: Provide a downhole oil-water separation device, including a swirl separation modular kit, the swirl separation modular kit having a housing and a housing connector, and its unique feature is that the swirl separation modular kit further includes,

[0015] an oil-phase overflow chamber, a first partition plate, a mixed-phase inlet chamber, a second partition plate, a total oil channel, a total water channel, a number of swirl separators, and a mixed-phase inlet pipe; wherein,

[0016] An annular arc-shaped groove is opened at the top of the upper connection platform of the housing, and the annular arc-shaped groove is connected to the total water channel pipeline;

[0017] Both the first partition plate and the second partition plate are threadedly connected to the inside of the housing, and after connection, two sealed cavities are formed with the inner wall of the housing, which are, from top to bottom, an oil-phase overflow chamber and a mixed-phase inlet chamber; holes for fixing the swirl separators and passing through the mixed-phase inlet pipe are opened on the first partition plate and the second partition plate; the oil-phase overflow chamber is connected to the total oil channel pipeline;

[0018] A swirl separator inlet groove is opened on the swirl separator. After the swirl separator is fixed on the second partition plate, the swirl separator inlet groove is located outside the second partition plate to receive the to-be-separated oil-water mixed-phase medium from the mixed-phase inlet chamber;

[0019] The mixed-phase inlet pipe is placed in the central holes of the first-stage partition plate and the second-stage partition plate, and circumferential holes are opened at the midpoint of the pipe corresponding to the position of the mixed-phase inlet cavity.

[0020] Total oil channels and total water channels that coincide with the positions on the housing are opened on the housing connector.

[0021] Solution 2: Provide a downhole oil-water separation device, which, on the basis of Solution 1, further includes a B-type quick-connector slot, a B-type quick connector, an upper alignment mark, and a lower alignment mark.

[0022] The B-type quick-connector slot and the upper alignment mark are arranged at the upper connection platform of the housing; the B-type quick connector and the lower alignment mark are arranged on the housing connector.

[0023] Solution 3: Provide a downhole oil-water separation device, which, on the basis of Solution 2, is provided with a ball-bar system on the hydrocyclone, and a ball-bar system slideway is arranged in the hole for fixing the hydrocyclone on the second-stage partition plate, so as to fix the hydrocyclone on the second-stage partition plate through the ball-bar system.

[0024] Solution 4: Provide a downhole oil-water separation device, which, on the basis of Solution 3, is provided with a Tesla valve in the total oil channel in the housing and the housing connector to prevent the reverse flow of the oil phase.

[0025] Solution 5: Provide a downhole oil-water separation device, which, on the basis of Solution 4, further includes a connector, an upper connection processor section, and a lower connection processor section.

[0026] The external structure of the connector is in the shape of a stepped boss cylinder. The small-diameter end is the connector oil-phase outlet pipe, and a ring-shaped rectangular groove is opened at its top to facilitate connection and sealing with the upper structure; the large-diameter end is the connector inlet pipe, and the oil-water mixed phase enters the interior through the mixed-phase empty area outside the connector oil-phase outlet pipe; a zero-level connection pipe alignment mark is provided at the bottom of the connector oil-phase outlet pipe for alignment with the next-level connection; at the same time, slots for placing the B-type quick connector are symmetrically opened circumferentially at 360°; a connector insertion slot is also provided inside the connector.

[0027] The upper section of the connection processor includes a primary connection platform at the top, a B-type quick connector slot, upper alignment marks and lower alignment marks on the connection processor, an oil-phase overflow chamber, a primary partition plate, a mixed-phase inlet chamber, a secondary partition plate, a main oil channel, a large-flow cyclone, and a mixed-phase inlet pipe; wherein both the primary partition plate and the secondary partition plate are threadedly connected inside the upper section of the connection processor, forming two cavities with the inner wall, namely the oil-phase overflow chamber and the mixed-phase inlet chamber. The middle of the mixed-phase inlet pipe is provided with circumferential holes. At a position slightly below the top of the hydrocyclone, 4 symmetrically arranged hydrocyclone inlet slots are circumferentially opened, and a ball-rod system for fixing the cyclone is provided at a position slightly below it. The secondary partition plate is symmetrically provided with 4 holes for placing the hydrocyclone in a 360° circumferential manner, and a ball-rod system slideway is provided in the holes;

[0028] The lower section of the connection processor is provided with upper alignment marks and lower alignment marks on the connection processor, and a Tesla valve is installed at the position of the main oil channel;

[0029] After the connector, the upper section of the connection processor, and the lower section of the connection processor are connected in sequence, an access end that can be docked with the same-well injection and production system is formed; after the lower section of the connection processor, a hydrocyclone separation modular kit is connected.

[0030] Solution 6: Provide a downhole oil-water separation device. On the basis of Solution 5, the device further includes a plugging device; the plugging device is connected to the lower end of the last-stage hydrocyclone separation modular kit for bottom plugging;

[0031] The top of the plugging device has the same structure as the top of the upper connection platform of the housing. The setting of the main oil channel is cancelled, but a water chamber and a converging water channel are provided; the position of the converging water channel corresponds to the position of the main water channel in the hydrocyclone separation modular kit and can be connected after docking to achieve communication. The converging water channel is connected to the water chamber; the annular arc-shaped groove at the top is connected to the water chamber pipeline; the water chamber is used to be connected to the pipeline of the reinjection pump to achieve the reinjection of the water phase after oil-water separation.

[0032] After applying any one of the foregoing methods or the device to the existing same-well injection and production process, several same-well injection and production systems with the same downhole oil-water separation working principle can be obtained. The same-well injection and production systems all include a lifting pump, a reinjection pump, and other conventional process components. Without process transformation, they can be directly connected to the same-well injection and production system driven by a dual-motor and dual-pump. The oil phase separated by the downhole oil-water separation device is lifted to the oil production platform by the lifting pump after being aggregated in the common oil channel, and the separated water phase is reinjected into the underground by the reinjection pump. If it needs to be applied to the same-well injection and production system driven by a single-motor and dual-pump, the mixed-phase inlet pipe passing through the connector, the connection processor, and the hydrocyclone separation modular kit needs to be transformed, and it can be considered to make it simultaneously become the hollow drive shaft of the single motor.

[0033] The technical solutions described in this disclosure have the following beneficial effects:

[0034] First, for the downhole co-injection and production process, an innovative structure that can achieve multi-swirl parallelism in a small-diameter pipe is given, enabling high liquid inflow rate processing in the downhole co-injection and production process.

[0035] Second, the device structure given in this disclosure is simple, easy to manufacture, can achieve multi-stage processing, can be multi-stage paralleled according to various liquid inflow rates in the downhole co-injection and production, and according to different downhole working conditions, so it has high applicability.

[0036] Third, the device given in this disclosure uses a Type B quick connector as the connecting piece between device sections, enabling the overall structure to achieve modular connection, which is convenient for installation and maintenance.

[0037] In addition, the device given in this disclosure is provided with a unidirectional Tesla valve, which can ensure the reliable and stable operation of the device under different processing capacities.

[0038] In summary, the technical solution given in this disclosure, after being applied to the downhole co-injection and production wellbore, is applicable to high liquid production volume, solves the problem that it is difficult to match the downhole oil-water swirl separation treatment with the ultra-large liquid inflow rate in the current stage of co-injection and production. It improves the single-well recovery efficiency, saves the economic development cost, and completes the downhole reinjection of the water phase while realizing the oil phase lift. It can ensure the efficient separation of the oil and water phases at all times, complete the downhole reinjection of the water phase while realizing the oil phase lift, and save the economic development cost. At the same time, the designs of the parallel structure, Type B quick connector, and unidirectional Tesla valve are carried out, which can achieve the stable operation of the device under different processing conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings included in the specification and constituting a part of the specification, together with the specification, illustrate the exemplary embodiments, features, and aspects of the present disclosure and are used to explain the principles of the present disclosure.

[0040] Figure 1 Shows a process schematic diagram of a co-injection and production system according to an embodiment of the present disclosure.

[0041] Figure 2 Shows an overall view of a downhole oil-water separation device according to an embodiment of the present disclosure.

[0042] Figure 3 Shows an overall cross-sectional view of a swirl separation modular kit according to an embodiment of the present disclosure.

[0043] Figure 4 Shows an assembly diagram of a connector, a connection processor, and a swirl separation modular kit according to an embodiment of the present disclosure.

[0044] Figure 5 Shows the single-section assembly drawing of the cyclone separation modular kit according to an embodiment of the present disclosure.

[0045] Figure 6 Shows the assembly drawing of the connection processor and the cyclone separator assembly with the same structure inside the cyclone separation modular kit according to an embodiment of the present disclosure.

[0046] Figure 7 Shows the structure diagram of the lower end face of the secondary partition plate according to an embodiment of the present disclosure.

[0047] Figure 8 Shows the structure diagram of the connector according to an embodiment of the present disclosure.

[0048] Figure 9 Shows the cross-sectional view of the connector according to an embodiment of the present disclosure.

[0049] Figure 10 Shows the structure diagram of the upper section of the connection processor according to an embodiment of the present disclosure.

[0050] Figure 11 Shows the cross-sectional view of the upper section of the connection processor according to an embodiment of the present disclosure.

[0051] Figure 12 Shows the structure diagram of the lower section of the connection processor according to an embodiment of the present disclosure.

[0052] Figure 13 Shows the cross-sectional view of the lower section of the connection processor according to an embodiment of the present disclosure.

[0053] Figure 14 Shows the structure diagram of the cyclone separation modular kit after removing the housing connector according to an embodiment of the present disclosure.

[0054] Figure 15 Shows the cross-sectional view of the cyclone separation modular kit after removing the housing connector according to an embodiment of the present disclosure.

[0055] Figure 16 Shows the structure diagram of the housing connector of the cyclone separation modular kit according to an embodiment of the present disclosure.

[0056] Figure 17 Shows the cross-sectional view of the structure diagram of the housing connector of the cyclone separation modular kit according to an embodiment of the present disclosure.

[0057] Figure 18 Shows the structure diagram of the plugging device according to an embodiment of the present disclosure.

[0058] Figure 19 Shows the cross-sectional view of the structure of the housing connector of the cyclone separation modular kit according to an embodiment of the present disclosure.

[0059] In the figure: 1 - connector, 101 - oil phase outlet pipe, 102 - connector inlet, 103 - mixed phase empty area, 104 - connector alignment mark, 105 - connector type B quick coupling, 106 - connector insertion slot, 107 - mixed phase inlet; 2 - upper section of the connection processor, 201 - processor connection platform, 202 - processor type B quick coupling card slot, 203 - upper alignment mark of the processor, 204 - lower alignment mark of the processor, 205 - processor oil phase overflow chamber, 206 - primary partition plate, 207 - mixed phase inlet cavity, 208 - secondary partition plate, 209 - total oil channel, 210 - hydrocyclone separator, 211 - mixed phase inlet pipe, 212 - hydrocyclone separator inlet slot, 213 - bat system, 214 - bat system slot; 3 - lower section of the connection processor, 301 - upper alignment mark of the lower section of the connection processor, 302 - lower alignment mark of the lower section of the connection processor, 303 - Tesla valve; 4 - hydrocyclone separation modular kit, 401 - total water channel, 402 - diversion water channel, 403 - bottom water phase convergence groove, 404 - oil channel; 5 - housing connector; 6 - plug, 601 - water cavity; 7 - offshore oil production platform; 8 - lift pump, 801 - liquid inlet hole; 9 - casing, 901 - casing inlet; 10 - reinjection pump. Detailed implementation manners

[0060] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the drawings denote elements having the same or similar functions. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0061] The special term "exemplary" herein means "serving as an example, embodiment or illustration". Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or better than other embodiments.

[0062] In addition, for a better illustration of the present disclosure, numerous specific details are given in the following detailed implementation manners. Those skilled in the art should understand that the present disclosure can be implemented without these specific details. In some instances, methods, technical means well known to those skilled in the art are not described in detail so as to highlight the gist of the present disclosure.

[0063] The embodiments of the present disclosure provide a downhole oil-water separation method, device and injection-production system, which can be applied in the field of co-well injection and production of oil resource development, and are particularly suitable for the case of co-well injection and production on an offshore platform. The following is a detailed description with reference to the accompanying drawings:

[0064] Figure 1It is a schematic diagram of the process of the same-well injection and production system for an offshore oil production platform. In the figure, the lifting pump 8 lifts the oil phase after oil-water separation to the offshore oil production platform 7. There is a casing inlet 901 on the casing 9, and the oil-water mixed phase enters the casing 9 from here, and then enters this device through the liquid inlet hole 801. The reinjection pump 10 reinjects the water phase after oil-water separation to the seabed.

[0065] Figure 2 It is an overall diagram of the modular cyclone separation device applicable to high liquid production volume in the same-well injection and production wellbore. The connector 1 is the transitional connection between the same-well injection and production process system and this device. The modular cyclone separation system and the same-well injection and production process are combined through the connector 1. Below the connector 1, it is connected to the upper section 2 of the connection processor and the lower section 3 of the connection processor through a quick connector buckle. After that, the cyclone separation modular kit 4 and the housing connector 5 are connected downward in sequence. The cyclone separation modular kit 4 and the housing connector 5 can be combined into this device in a complete set according to requirements, and finally, the plugging device 6 plugs the bottom end of the whole device.

[0066] Figure 3 It is a sectional view of the modular cyclone separation device applicable to high liquid production volume in the same-well injection and production wellbore. Inside the modular kit 4, there are 4 large-flow cyclone separators 210 suitable for large liquid discharge volume for oil-water separation.

[0067] Figure 4 It is an assembly drawing of the modular cyclone separation device applicable to high liquid production volume in the same-well injection and production wellbore. The upper modular kit 4 and the lower modular kit 5 are connected by thread to form a single section, and the sections are connected by a type B quick connector buckle.

[0068] Figure 5 It is a single-section assembly drawing of the modular cyclone separation device applicable to high liquid production volume in the same-well injection and production wellbore. The first-stage partition plate 206 and the second-stage partition plate 208 are connected to the inside of the upper modular kit 4 by a threaded connection. The large-flow cyclone 210 is the main component for oil-water separation. The Tesla valve 303 is installed in the main oil pipe 209 to achieve one-way conduction and avoid backflow blockage.

[0069] Figure 6 It is an assembly drawing of the large-flow cyclone separator. The cyclone separator 210 is fixed to the second-stage partition plate 208 with the help of the ball-rod system 213. The ball-rod system 213 is composed of a rod and a ball at the top of the rod, and is symmetrically distributed on both sides of the cyclone separator 210.

[0070] Figure 7 It is a structural diagram of the lower end face of the second-stage partition plate 208. The ball-rod system groove 214 can fix the ball-rod system 213, thereby realizing the fixation of the large-flow cyclone separator 210. During installation, first connect the first-stage partition plate 206 and the second-stage partition plate 208 by thread, and then fix the large-flow cyclone separator 210 to the second-stage partition plate 208 through the ball-rod system 213 and the ball-rod system groove 214.

[0071] Figure 8 It is a structural diagram of the connector. In the diagram, the oil phase outlet pipe 101 is the total outlet for lifting the oil phase. The oil-water mixed phase enters the interior of this device through the mixed phase empty area 103 between the connector inlet 102 and the oil phase outlet pipe 101. Among them, the connector alignment mark 104 and the B-type quick connector 105 are devices for alignment and connection when connecting to the connection processor 2.

[0072] Figure 9 It is a cross-sectional view of the connector. The connector insertion slot 106 provides a slot for the top connection of the connection processor 2 and also plays a sealing role.

[0073] Figure 10 It is a structural diagram of the connection processor 2. The first-level connection platform 201 corresponds and cooperates with the connector insertion slot 106. The B-type quick connector slot 202 corresponds and cooperates with the B-type quick connector 105 in the connector 1. The first-level upper alignment mark 203 corresponds and aligns with the connector alignment mark 104. When a new section needs to be connected, just align the alignment marks and then pull the pull ring of the B-type quick connector 202 to achieve contact cooperation. The first-level lower alignment mark 204 is for the convenience of connecting the connection processor 3 below.

[0074] Figure 11 It is a cross-sectional view of the connection processor 2. Among them, the oil phase overflow chamber 205 is the position where the oil phase converges. The mixed phase inlet chamber 207 is the position where the mixed phase converges. The first-level partition plate 206 and the second-level partition plate 208 together with the inner wall form the above two cavities. The total oil channel 209 is the channel through which the oil phase passes after convergence. The large-displacement hydrocyclone 210 realizes the oil-water swirl separation. The mixed phase inlet pipe 211 is the total liquid inlet pipe that penetrates the connector, the connection processor, and the swirl separation modular kit, and it has openings at positions aligned with the horizontal level of the mixed phase inlet chamber 207 in each section.

[0075] Figure 12 It is a structural diagram of the lower part of the connection processor 3, which has two upper and lower alignment marks 301 and 302. Figure 13 It is a cross-sectional view of the lower part of the connection processor 3. A Tesla valve 303 is installed at the position of the total oil channel 209.

[0076] Figure 14 It is a structural diagram of the modular kit. An annular arc-shaped groove is machined at the top of the modular kit, which is the position where the bottom-flow water phase converges. Figure 15 It is a cross-sectional view of the upper part of the modular kit. A total water channel 401 is opened at a position symmetrical to the total oil channel 209. The total water channel 401 is the channel through which the water phase passes after convergence after oil-water separation. The separated water phase first converges in the liquid leakage tank 403 and then enters the total water channel 401 through the bottom flow channel 402. The oil channel 404 is the channel through which the oil phase passes after convergence after oil-water separation. Figure 16It is the structural diagram under the modular kit. Figure 17 It is the sectional view under the modular kit. The main water channel 401 is opened at the symmetric position of the main oil channel 209, and the rest of the structure is the same as that of the 3 under the connection processor. Figure 18 It is the structural diagram of the plugging device. The upper end structure is the same as that of the 4 upper end of the modular kit. Figure 19 It is the sectional view of the plugging device. A water cavity 601 is opened inside it. The water phase finally converges into the water cavity 601 through the main water channel 401, and the water phase is reinjected into the seabed under the action of the reinjection pump 10.

[0077] The downhole fluid enters the mixed-phase inlet pipe 211, enters the mixed-phase inlet cavity 207 through the pipe hole of the mixed-phase inlet pipe 211. Due to continuous inflow of fluid, the pressure in the cavity gradually increases. The mixed phase enters the cyclone through the upper slot of the large-displacement cyclone 210. Under the action of the spiral flow channel, the movement direction of the fluid flow is changed from axial to tangential to achieve swirl separation. The separated oil phase accumulates at the axial center of the large-displacement cyclone 210 and enters the oil-phase overflow cavity 205 through the pipeline. The oil-phase overflow cavity 205 has an opening in the side wall and converges into the main oil channel 209, and finally the oil phase is lifted and collected under the action of the lifting pump 8. The separated water phase enters the arc-shaped groove from the bottom end of the large-displacement cyclone 210. Similarly, an inclined flow channel is provided at the lower end of the arc-shaped groove. The water phase enters the main water channel 401 through the inclined flow channel. The main water channel 401 is connected to the water cavity 601 at the bottom end. After the water phase finally converges into the water cavity 601, it is reinjected into the formation under the action of the reinjection pump 10 to achieve the injection and recovery of large-displacement oil and water in a single well downhole.

[0078] When the device is running, the oil-water mixture to be exploited outside the downhole casing enters the casing through the perforations of the casing. The mixed-phase medium composed of the oil-water mixture passes through the mixed-phase empty area between the oil-phase outlet pipe and the connector inlet pipe and enters the mixed-phase inlet pipe in the first-stage processor through the connector. The mixed-phase inlet pipe has a hole between the first-stage partition plate and the second-stage partition plate inside the first-stage processor. The mixed phase enters the mixed-phase inlet cavity through the hole, and then enters the large-flow cyclone through the cyclone inlet slot. The flow direction of the mixed phase is changed to tangential through the spiral flow channel inside the cyclone, and swirl separation is achieved according to the different densities of oil and water.

[0079] The main oil passage and the main water passage are both equipped with Tesla valves. A Tesla valve is a one-way valve, whose function is to prevent the backflow and blockage of the oil phase and the water phase. The overall scheme of the device is that the downhole fluid enters the mixing-phase inlet pipe, passes through the pipe holes of the mixing-phase inlet pipe and enters the mixing-phase inlet cavity. Due to continuous liquid inflow, the pressure in the cavity gradually increases. The mixing phase enters the cyclone through the upper groove of the large-displacement cyclone. Under the action of the spiral flow channel, the movement direction of the liquid flow is changed from axial to tangential to achieve swirl separation. The separated oil phase accumulates at the center of the axis of the large-displacement cyclone and enters the oil-phase overflow cavity through the pipeline. The oil-phase overflow cavity has an opening on the side wall and converges into the main oil passage. Finally, under the action of the lifting pump, the oil phase is lifted and collected. The separated water phase enters the arc-shaped groove from the bottom end of the large-displacement cyclone. Similarly, an inclined flow channel is provided at the lower end of the arc-shaped groove. The water phase passes through the inclined flow channel and enters the main water passage. The main water passage is connected to the water cavity at the bottom end. After the water phase finally converges into the water cavity, it is reinjected into the formation under the action of the reinjection pump to achieve the injection and recovery of large-displacement oil and water in a single well underground.

[0080] The modular swirl separation device applicable to high liquid production in the same-well injection and production wellbore proposed by the present invention solves the problem of the difficulty in matching the current same-well injection and production oil-water swirl separation system with the ultra-large treatment capacity technology. It improves the single-well recovery efficiency, saves the economic development cost, and completes the downhole reinjection work of the water phase while lifting the oil phase.

Claims

1. An underground oil-water separation device for an injection-production well in the same well, comprising a hydrocyclone separation modular kit, a B-type quick connector slot, a B-type quick connector, an upper alignment mark, and a lower alignment mark; The hydrocyclone separation modular kit has a housing and a housing connector. The hydrocyclone separation modular kit further includes an oil-phase overflow chamber, a primary partition plate, a mixed-phase inlet chamber, a secondary partition plate, a total oil channel, a total water channel, a plurality of hydrocyclones, and a mixed-phase inlet pipe; Among them, An annular arc-shaped groove is opened at the top of the upper connection platform of the housing, and the annular arc-shaped groove is connected to the total water channel pipeline; The primary partition plate and the secondary partition plate are both threadedly connected to the inside of the housing. After connection, two sealed cavities are formed with the inner wall of the housing, which are, from top to bottom, an oil-phase overflow chamber and a mixed-phase inlet chamber respectively; holes for fixing the hydrocyclones and passing through the mixed-phase inlet pipe are opened on the primary partition plate and the secondary partition plate; the oil-phase overflow chamber is connected to the total oil channel pipeline; A hydrocyclone inlet slot is opened on the hydrocyclone. After the hydrocyclone is fixed on the secondary partition plate, the hydrocyclone inlet slot is located outside the secondary partition plate to receive the oil-water mixture medium to be separated from the mixed-phase inlet chamber; The mixed-phase inlet pipe is placed in the central holes of the primary partition plate and the secondary partition plate, and circumferential holes are opened at the middle end of the pipe corresponding to the position of the mixed-phase inlet chamber; The housing connector is provided with a total oil channel and a total water channel that coincide with the positions on the housing; a Tesla valve is provided in the total oil channel in the housing and the housing connector to prevent the reverse flow of the oil phase; The B-type quick connector slot and the upper alignment mark are provided at the upper connection platform of the housing; the B-type quick connector and the lower alignment mark are provided on the housing connector; A ball-bar system is provided on the hydrocyclone, and a ball-bar system slideway is provided in the hole for fixing the hydrocyclone on the secondary partition plate to fix the hydrocyclone on the secondary partition plate through the ball-bar system; It is characterized in that: The device further includes a connector, an upper connection processor section, and a lower connection processor section; The connector has a stepped boss cylindrical appearance structure. The small-diameter end is the connector oil-phase outlet pipe, and an annular rectangular groove is opened at the top thereof for easy connection and sealing with the upper-end structure; the large-diameter end is the connector inlet pipe, and the oil-water mixture enters the interior through the mixed-phase empty area outside the connector oil-phase outlet pipe; a zero-level connection pipe alignment mark is provided at the bottom of the connector oil-phase outlet pipe for alignment with the next-level connection; at the same time, slots for placing B-type quick connectors are symmetrically opened circumferentially at 360°; a connector insertion slot is also provided inside the connector; The upper section of the connection processor includes a primary connection platform at the top, a B-type quick connector slot, upper and lower alignment marks on the connection processor, an oil-phase overflow chamber, a primary partition plate, a mixed-phase inlet chamber, a secondary partition plate, a main oil passage, a high-flow cyclone, and a mixed-phase inlet pipe. The primary and secondary partition plates are both threadedly connected inside the upper section of the connection processor, forming two cavities with the inner wall, namely the oil-phase overflow chamber and the mixed-phase inlet chamber. The middle of the mixed-phase inlet pipe is provided with circumferential holes. At a position slightly below the top of the hydrocyclone, 4 symmetrically arranged hydrocyclone inlet slots are circumferentially opened. At a position slightly below it, a bat system for fixing the cyclone is provided. The secondary partition plate is circumferentially and symmetrically provided with 4 holes for placing the hydrocyclone, and a bat system slideway is provided in the holes. The lower section of the connection processor is provided with upper and lower alignment marks on the connection processor, and a Tesla valve is installed at the position of the main oil passage. After the connector, the upper section of the connection processor, and the lower section of the connection processor are sequentially connected, an access end that can be docked with the same-well injection and production system is formed. After the lower section of the connection processor, a hydrocyclone separation modular kit is connected.

2. The downhole oil-water separation device for the same-well injection and production well according to claim 1, wherein: The device further includes a plugging device; the plugging device is connected to the lower end of the last-stage hydrocyclone separation modular kit for bottom plugging. The top of the plugging device has the same structure as the top of the upper connection platform of the housing. The setting of the main oil passage is cancelled, but a water chamber and a converging water passage are provided. The position of the converging water passage corresponds to the position of the main water passage in the hydrocyclone separation modular kit and can be docked to achieve communication. The converging water passage is connected to the water chamber. The annular arc-shaped groove at the top is connected to the water chamber pipeline. The water chamber is used to be connected to the pipeline of the reinjection pump to realize the reinjection of the water phase after oil-water separation.

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