Vertical separation tank, and oil-water-gas three-phase separation, recovery and metering apparatus and method

Abstract

The present invention relates to the technical field of oil-water-gas three-phase fluid measurement device manufacturing, and in particular to a vertical separation tank having a compact structure and capable of performing stable, continuous and high-precision monitoring on oil-water-gas three-phase fluids. The vertical separation tank is provided with an input port, and is characterized by internally comprising a first isolation area and a second isolation area: the first isolation area is used for buffering input multiphase flow, wherein a side port of the first isolation area is communicated with the input port, an upper port of the first isolation area is communicated with a top space in the separation tank, a lower port of the first isolation area is communicated with a middle lower space in the separation tank, and the first isolation area is configured such that three-phase flow can be primarily separated; and the second isolation area is used for stabilizing and secondarily separating a mixture of free water and emulsified oil from the first isolation area.

Description

Vertical separation tank and three-phase oil and gas separation and recovery metering device and method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311821381.5 filed on December 27, 2023, entitled “Vertical separation tank and three-phase oil and gas separation, recovery and metering device and method”, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of manufacturing equipment for measuring oil-water-gas three-phase fluids, and in particular to a compact vertical separation tank and a three-phase oil-gas separation and recovery metering device and method capable of stably, continuously and with high precision monitoring of the oil-water-gas three-phase fluids. Background Art

[0004] In oil production, accurate and stable monitoring and recovery of the three phases of oil, water and gas are the basis for increasing oilfield revenue, reducing costs and achieving digital production. On the one hand, each oil well or well group needs to stably and accurately measure the crude oil, water and natural gas produced. The invention patent "Oil Content Measuring Method and Device for Oil Well Produced Liquid (201280001771.1)" previously proposed by the inventor of this patent provides a method for measuring oil well produced liquid in an intermittent manner, which has the characteristics of accurate measurement, stability and strong adaptability, but is not convenient for continuous measurement of oil, water and gas; on the other hand, in some cases, it is necessary to process the oil well produced liquid into crude oil (or emulsified oil), free water and natural gas on site, and to achieve continuous measurement of oil, water and gas, thereby achieving separation, separate transmission and separate measurement.

[0005] In response to the demand for single-well measurement in oil fields, domestic technicians in the field have proposed a technology for continuous measurement of three-phase flow based on the separation of oil, water and gas, such as the system described in Patent 200420022701.7. However, the three-phase separation continuous measurement system based on the horizontal separation tank, although convenient for the production and transportation of the device, has low efficiency in separating and controlling oil, water and gas, and poor ability to adapt to the oil, water and gas flow and its changes. For the same oil, water and gas multiphase flow production, a larger and more space-consuming separation tank system is required, and the system cost and complexity will increase exponentially, but its ability to adapt to on-site oil, water and gas changes has not increased accordingly, causing great difficulties for the different needs of oilfield production; whether from the perspective of floor space or overall cost, it has lost the rationality of promotion; in addition, the horizontal tank structure compresses the vertical distribution and change space of oil, water and gas, and puts forward excessively high requirements for the control of the total liquid level and the oil-water interface, making it difficult for existing field instruments and their control technologies to meet the requirements for separation, measurement or transmission of oil (emulsified oil), water and gas, and cannot measure some scenarios where the liquid production and gas production are irregular or less than the corresponding pipeline flow meter range.

[0006] Summary of the Invention

[0007] In view of the shortcomings and deficiencies in the prior art, the present invention proposes a vertical separation tank and a three-phase oil and gas separation and recovery metering device and method with a compact and reasonable structure, high cost performance, and the ability to quickly regulate the oil, water and gas flow state to achieve oil, water and gas separation, transmission and measurement.

[0008] The present invention is achieved by the following measures:

[0009] A vertical separation tank, comprising:

[0010] An input port 101 is provided at the upper middle portion of the separation tank 1 and is used to introduce a multiphase flow into the metering separation tank 1; the multiphase flow includes a mixture of free water, emulsified oil and gas;

[0011] The first output port 102 is provided at the bottom of the separation tank 1 and is used to output the separated free water;

[0012] The second output port 103 is provided in the middle of the separation tank 1 and is used to output the separated emulsified oil;

[0013] The third output port 104 is provided at the top of the separation tank 1 and is used to output the separated gas. The third output port 104 is characterized in that the separation tank 1 includes a first isolation zone and a second isolation zone.

[0014] The first isolation zone is used to buffer the input multiphase flow, and its side port is connected to the input port 101, the upper port is connected to the top space in the separation tank 1, and the lower port is connected to the middle and lower space in the separation tank 1. The first isolation zone is configured so as to achieve a primary separation of the three-phase flow, and the gas after the primary separation can enter the top space in the separation tank 1 through the upper port, and the free water and emulsified oil mixture can enter the middle and lower space in the separation tank 1 through the lower port; and

[0015] The second isolation zone is used to stabilize and secondary separate the free water and emulsified oil mixture from the first isolation zone, wherein the first output port 102, the second output port 103 and the third output port 104 are all connected to the second isolation zone to discharge the separated free water, emulsified oil and gas respectively.

[0016] The multiphase flow in the neutral separation tank of the present invention performs a downward circulation motion in the first isolation zone.

[0017] In the present invention, an isolation protection cylinder 5 is provided above the interior of the separation tank 1 , and a vent is left at the top of the isolation protection cylinder 5 to maintain gas communication between the inside and outside of the isolation protection cylinder 5 .

[0018] The present invention further extends the input port 101 into the isolation protection tube 5 along the tangential direction of the isolation protection tube 5. At this time, the upper middle area in the isolation protection tube 5 is the first isolation zone to guide the fluid input into the separation tank 1 to perform horizontal swirling motion along the inner side of the tank body.

[0019] The input port 101 of the present invention does not extend into the isolation protective cylinder 5. The space between the separation tank 1 and the isolation protective cylinder 5 is the first isolation zone, so that the liquid that first enters the separation tank 1 performs a spiral downward movement in the space between the separation tank 1 and the isolation protective cylinder 5, and realizes the preliminary separation of the emulsion and free water; further, the multiphase flow input port 101 is arranged along the horizontal tangent direction of the inner side of the cylindrical vertical metering separation tank 1 to guide the fluid input into the separation tank 1 to perform a horizontal swirling movement along the inner side of the tank body.

[0020] The isolation protection cylinder 5 of the present invention is fixed to the separation tank 1 by a support rod. Preferably, the isolation protection cylinder 5 is coaxially arranged with the separation tank 1 to facilitate the liquid that first enters the separation tank 1 to make a spiral downward movement along the primary separation buffer zone and realize the preliminary separation of the emulsion and free water.

[0021] After the oil-water mixture of the present invention flows into the lower part of the isolation protection tube 5, the emulsified oil and free water continue to separate and flow in the opposite direction. The free water moves downward and the emulsified oil moves upward along the inner side of the isolation protection tube 5, forming a second isolation zone between the inner side of the isolation protection tube 5 and the middle and lower space of the separation tank 1.

[0022] In addition, according to one embodiment of the present invention, the separation tank 1 also includes a measuring device 6, which is arranged in the second isolation zone and extends longitudinally along the second isolation zone, and is used to measure the oil-water interface and / or liquid level position and / or output the water content information of the emulsified oil.

[0023] In addition, according to one embodiment of the present invention, the measuring device 6 includes an integrated oil-water interface and liquid level measurement component with a segmented oil-water analysis function.

[0024] In order to further optimize the flow path of oil and water in the separation tank 1 and improve the efficiency of oil-water separation and the utilization rate of the separation tank 1, the present invention provides at least one layer of corrugated plate packing layer 107 in the second isolation zone of oil, water and gas. On the one hand, it is used to increase the chance of oil and water contact separation and improve the separation efficiency. On the other hand, it is used to stabilize the liquid level of emulsified oil and free water moving upward and downward, and ensure the stability of the emulsified oil and free water exported. The corrugated plate packing layer 107 here plays an auxiliary role, and the more the better. Considering the space utilization in the separation tank 1 and the transportation and installation convenience of the equipment, the thickness of the corrugated plate packing layer 107 is between 10 and 80 cm.

[0025] The present invention further provides a corrugated plate packing layer 107 at the middle and lower part of the separation tank 1 and the lower part of the isolation protection tube 5. The outer diameter of the corrugated plate packing layer 107 is respectively adapted to the inner diameter of the separation tank 1 and the isolation protection tube 5, and the thickness is 20 cm.

[0026] The present invention also proposes a three-phase oil and gas separation, recovery and metering device, characterized in that it is provided with a vertical separation tank body as described above, the first output port 102 is connected to the free water output pipeline; the second output port 103 is connected to the emulsified oil output pipeline; the third output port 104 is connected to the gas output pipeline; a free water control valve 201 is provided on the free water output pipeline 2 connected to the first output port 102; an emulsified oil control valve 301 is provided on the emulsified oil output pipeline 3 connected to the second output port 103; a gas control valve 401 is provided on the gas output pipeline 4 connected to the third output port 104, the emulsified oil output pipeline 3 is located inside the separation tank 1 and extends into the interior of the isolation protection cylinder 5 (second isolation area), and the sampling port of the emulsified oil output pipeline 3 is located below the liquid level and in the upper middle position of the isolation protection cylinder 5 to extract stable emulsified oil.

[0027] The second isolation zone of the present invention is provided with an oil-water interface and liquid level measurement component, which can be an integrated oil-water interface and liquid level measurement component using the segmented electrical parameter measurement principle, or an independent oil-water interface meter and a liquid level meter integrated, preferably an integrated oil-water interface and liquid level measurement component using the segmented electrical parameter measurement principle. The function of these measurement components or instruments is to provide a basis for the regulation of the free water control valve 201, the emulsified oil control valve 301 and the gas control valve 401: when the oil-water interface is low, for example, the distance from the first output port 102 is 10cm-30cm , reduce the opening of the free water control valve 201 to prevent the emulsified oil from flowing out through the free water pipeline; when the total liquid level is high, for example, the distance between the total liquid level and the third output port 104 is 10cm-30cm, reduce the opening of the gas control valve 401 to prevent the emulsified oil from flowing out through the associated gas pipeline; when the oil-water interface is high, for example, the distance from the second output port 103 is 10cm-30cm, reduce the opening of the emulsified oil control valve 301 to reduce the outflow speed of the emulsified oil through the emulsified oil pipeline; vice versa, the same principle applies to ensure that free water, emulsified oil, and associated gas are output from their respective pipelines.

[0028] In the present invention, by setting a water flow meter 202 on the drainage pipe 2, the separated free water can be measured; by setting a gas flow meter 402 on the gas output pipeline 4, the separated associated gas can be measured; by setting an emulsified oil flow meter 302 and an oil-water analyzer 303 on the emulsified oil output pipeline 3, the oil and water contained in the emulsified oil can be measured; or, by setting an emulsified oil flow meter 302 on the emulsified oil output pipeline 3 and setting an in-tank oil-water measuring unit 32 in the tank body, the oil and water contained in the emulsified oil can be measured; or, by setting a mass flow meter on the emulsified oil output pipeline 3, the oil and water contained in the emulsified oil can be measured; the total of the free water flowing through the drainage pipe 2 and the water measured in the emulsified oil pipeline 3 is the amount of water in the oil-water-gas three-phase flow, thereby realizing the separation, measurement and transmission of the oil-water-gas three-phase flow.

[0029] For safety reasons and to further improve the quality of oil-water-gas three-phase separation and metering, the present invention further provides a temperature meter 105 and a pressure meter 106 on the separation tank 1 or the corresponding pipeline.

[0030] In order to further improve the efficiency of measurement and calculation, the present invention is also provided with a data processing and control unit 7, which is electrically connected to the control valves 201, 301, 401, flow meters 202, 302, 402, oil-water analyzer 303, oil-water interface and liquid level measuring device 6 or oil-water interface meter 61 and liquid level meter 62, temperature transmitter 105, pressure transmitter 106, etc.

[0031] The present invention adopts the principle of segmented electrical parameter measurement and has an integrated oil-water interface and liquid level measuring device with an oil-water analysis function. It can also realize the measurement of the water content of the emulsified oil flowing through the emulsified oil output pipeline 3 by setting the relative position and direction of the sampling port of the emulsified oil output pipeline 3 and the corresponding measuring section of the integrated oil-water interface and liquid level measuring device, thereby further simplifying the design of the emulsified oil output pipeline 3; for occasions where oil, water and gas are not required to be transported separately, the ends of the drainage pipe 2, the emulsified oil output pipeline 3 and the gas output pipeline 4 are merged, and the oil, water and gas multiphase flow is concentrated and output externally, thereby further improving the compactness of the device on the basis of completing the three-phase metering of the oil, water and gas multiphase flow.

[0032] The present invention also proposes a three-phase oil and gas separation and recovery metering method, which is characterized by comprising the following steps:

[0033] Step 1: Multiphase flow injection: Using the above-mentioned three-phase oil and gas separation and recovery metering device, a dynamic oil-water-gas multiphase flow is injected from the inlet 101 of the separation tank 1, and the multiphase flow is injected horizontally into the primary separation buffer zone, which is the space between the separation tank 1 and the isolation protection cylinder 5;

[0034] Step 2: Preliminary separation of multiphase flow: The multiphase flow injected into the separation tank 1 flows horizontally in the annular oil-water-gas primary isolation zone under the influence of its own kinetic energy and the differences in characteristics between the different phases of fluid, achieving gas-liquid separation. The separated gas moves upward and is output through the gas output port, i.e., the third output port 104, while the separated oil-water mixture moves downward uniformly, achieving preliminary oil-water separation.

[0035] Step 3: Secondary stabilization and separation of multiphase flow: The oil-water mixture after preliminary separation enters the secondary separation stabilization zone of oil, water and gas through the bottom of the isolation protection tube 5 for further stabilization and separation. The separated emulsified oil gradually rises in the secondary separation stabilization zone, and the water content gradually decreases. The separated free water gradually moves downward in the secondary separation stabilization zone, and the oil content becomes lower and lower. The separated emulsified oil extends into the sampling port inside the isolation protection tube 5 through the emulsified oil output pipeline 3, and is output to the outside through the emulsified oil output pipeline 3. The separated free water is output to the outside through the free water output port at the bottom, i.e., the first output port 102.

[0036] In step 3 of the present invention, with the help of monitoring of the oil-water interface and liquid level measuring components placed in the secondary separation stable zone, the positions of the oil-water interface and the total liquid level are controlled by jointly regulating the free water control valve 201, the emulsified oil control valve 301 and the gas control valve 401. The role of the oil-water interface and liquid level measuring components is to provide a basis for regulating the free water control valve 201, the emulsified oil control valve 301 and the gas control valve 401. When the oil-water interface is low, the opening of the free water control valve 201 is reduced to prevent the emulsified oil from flowing out through the free water pipeline; when the total liquid level is high, the opening of the gas control valve 401 is reduced to prevent the emulsified oil from flowing out through the associated gas pipeline; when the thickness of the emulsified oil layer is small, the opening of the emulsified oil control valve 301 is reduced to reduce the outflow rate of the emulsified oil through the emulsified oil pipeline. degree; the control principle is the same in reverse, which can ensure that the free water discharged from the drainage pipe 2 basically does not contain crude oil, and at the same time ensure that the sampling port 105 of the emulsified oil pipeline is always placed in a relatively stable emulsified oil layer, and when the oil-water measuring probe 601 on the oil-water analyzer array 6 or the oil-water analysis measuring instrument 303 provided on the emulsified oil output pipeline 3 is used to measure the oil content of the emulsified oil output, the measurement is kept accurate and stable; combined with the flow meter 202 on the free water pipeline 2, the flow meter 302 on the emulsified oil pipeline 3, and the gas flow meter 402 provided on the gas pipeline 4, the oil flow, water flow, and gas flow of the oil-water-gas multiphase flow can be obtained; if necessary, the diverted free water, emulsified oil, and associated gas can be separately transmitted through the free water pipeline 2, the emulsified oil pipeline 3, and the gas pipeline 4.

[0037] Compared with the prior art, the present invention has the following advantages: (1) By utilizing a vertical cylindrical separation tank, and taking advantage of the kinetic energy of the oil-water-gas multiphase flow itself and the density and other characteristic differences between oil, water and gas, the paths and directions of oil flow, water flow and air flow are reasonably guided, and the rapid separation of emulsified oil, free water and associated gas is achieved in a very small space, and a stable flow state is formed, which is particularly beneficial to the gas-liquid separation of high-yield gas wells, and the continuous separation and measurement of the oil-water-gas three-phase flow is achieved, ensuring the stable and accurate measurement of oil and gas production, and providing an important tool for the informatization and intensification of oil field production. (2) The vertical structure lengthens the size of the oil-water-gas secondary separation stable zone in the vertical direction, reduces the difficulty of controlling the liquid level and oil-water interface, simplifies the control system, and improves the efficiency and quality of oil-water control. It has a compact structure, small size, and low cost. Compared with horizontal separation tanks with corresponding three-phase separation capabilities, it saves 60%-90% of the floor space. For example, the height of the separation tank can be made less than 2 meters, which is cost-effective and suitable for promotion. (3) It can realize continuous measurement of oil, water and gas, and can also perform intermittent measurement under specific circumstances such as exceeding the flow meter range. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG1 is a schematic structural diagram of embodiment 1 of the present invention.

[0039] FIG2 is a structural diagram of an integrated oil-water interface and liquid level measurement assembly in Example 1 of the present invention, which adopts the segmented electrical parameter measurement principle.

[0040] FIG3 is a schematic structural diagram of embodiment 2 of the present invention.

[0041] FIG4 is a schematic diagram of a second implementation structure of the first isolation region and the second isolation region in the present invention.

[0042] FIG5 is a schematic diagram of the structure for converging and externally transmitting the separated and measured emulsified oil, free water, and associated gas in Example 2 of the present invention.

[0043] FIG6 is a schematic diagram of an integrated liquid level and oil-water interface monitoring device with segmented oil-water analysis function according to the present invention.

[0044] FIG7 is a schematic diagram of the arrangement of the input port on the separation tank in Example 1 of the present invention.

[0045] FIG8 is a schematic diagram of the liquid injection state of the separation tank shown in FIG7 .

[0046] Reference numerals: 1 separation tank; 101, input port; 102, first output port; 103, second output port; 104, third output port; 105, temperature meter; 106, pressure meter; 107, corrugated plate filler; 2, drainage pipe; 201, free water control valve; 202, water flow meter; 3, emulsified oil output pipeline; 301, emulsified oil control valve; 302, emulsified oil flow meter; 303, pipeline oil-water analyzer; 304, pipeline type tester Measuring chamber; 305, mass flowmeter; 31, emulsified oil sampler in the tank; 32, oil-water measuring unit in the tank; 4, gas output pipeline; 401, gas control valve; 402, gas flowmeter; 5, isolation protection tube; 6, integrated oil-water interface and liquid level measurement assembly; 601, upper emulsified oil area; 602, lower free water; 603, oil-water interface; 604, total liquid level; 61, oil-water interface meter; 62, liquid level meter; 7, data processing and control unit. DETAILED DESCRIPTION

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] As shown in Figure 1, the present application first provides a separation tank 1, comprising: an input port 101, arranged in the middle and upper part of the separation tank 1, for introducing a multiphase flow into the metering separation tank 1; the multiphase flow comprises a mixture of free water, emulsified oil and gas; a first output port 102, arranged at the bottom of the separation tank 1, for outputting the separated free water; a second output port 103, arranged in the middle of the separation tank 1, for outputting the separated emulsified oil; a third output port 104, arranged at the top of the separation tank 1, for outputting the separated gas, and the separation tank 1 comprises a first isolation zone and a second isolation zone: wherein the height of the first isolation zone is less than the height of the separation tank 1, and has an upper port, a lower port and a side port, which are It is arranged in the middle and upper part of the separation tank 1, and is used to receive the three-phase flow input by the input port 101 through its side port and buffer it, and can realize the primary separation of the three-phase flow, and discharge the gas that has been separated once and the oil-water mixture that has been separated once through its upper port and its lower port respectively; wherein, the second isolation zone, which includes the remaining space in the separation tank 1 except the first isolation zone, is used to accommodate the gas that has been separated once from the first isolation zone and stabilize and secondary separate the oil-water mixture that has been separated once from the first isolation zone, and can discharge the water, oil and gas that have been separated twice through the first output port 102, the second output port 103 and the third output port 104 respectively.

[0049] An isolation protection tube 5 is provided within the separator tank 1 (see Figure 7). It has an opening communicating with the separator tank 1 and a lower opening. The isolation protection tube 5 is substantially coaxial with the separator tank 1, and its cross section substantially forms a concentric ring. The concentric annular space between the outer wall of the isolation protection tube 5 and the opposing inner wall of the separator tank 1 forms the first isolation zone. The separator tank interior space below the isolation protection tube 5, the interior space of the isolation protection tube 5, and the separator tank interior space above the isolation protection tube 5 form the second isolation zone.

[0050] In another embodiment of the separation tank 1, an isolation protection tube 5 is provided inside the separation tank 1, see Figure 4, which has an opening and a lower opening connected to the separation tank 1, wherein the isolation protection tube 5 is off-axis from the separation tank, and its cross-section forms an eccentric ring, and the internal space of the isolation protection tube 5 forms the first isolation zone (primary separation zone), and the internal space of the separation tank 1 at the lower part of the isolation protection tube 5, the eccentric annular space formed by the outer wall of the isolation protection tube 5 and the inner wall of the opposite separation tank 1, and the internal space of the separation tank at the upper part of the isolation protection tube 5 form the second isolation zone (secondary separation zone).

[0051] In addition, the separation tank 1 also includes a measuring device 6, which is vertically arranged in the second isolation zone and is used to measure the oil-water interface and / or liquid level position. Referring to Figures 2 and 6, the measuring device 6 of this embodiment can include an integrated oil-water interface and liquid level measurement assembly with a segmented oil-water analysis function. The sensor in the oil-water interface and liquid level measurement assembly is composed of a first electrode and a second electrode that are parallel to each other in the vertical direction and insulated from each other in the horizontal direction, wherein: the first electrode is composed of a group of tubular conductive segment electrodes in the vertical direction, the segment electrodes are fixed and insulated from each other by insulating material, and are electrically connected to the signal and data processing unit through wires located on the inner side of the segment electrodes; the outer side of the first electrode is wrapped with a uniform outer insulating layer, forming a combined rigid composite electrode, and each segment electrode of the first electrode is electrically connected to the signal and data processing unit through a separate lead or a selection bus.

[0052] The second electrode accompanies the first electrode in the vertical direction and is electrically connected to the signal and data processing unit. The space between the first electrode and the second electrode is the measurement space of the sensor. A channel is left on the second electrode to facilitate the medium to enter and exit the measurement space.

[0053] In the spatial relationship between the first electrode and the second electrode, the second electrode partially or completely surrounds the first electrode in the horizontal direction; in the vertical direction, the outer conductive surface of the first electrode and the inner conductive surface of the second electrode are parallel to each other; each segment electrode of the first electrode and the corresponding part of the second electrode constitute a segmented sensor with oil-water analysis function, and the first electrode and the second electrode are isolated and fixed together by an insulating part, forming an integrated liquid level and oil-water interface monitoring device with segmented oil-water analysis function as a whole.

[0054] The integrated oil-water interface and liquid level measurement component with segmented oil-water analysis function can be, for example, a commercial multiphase oil-water interface instrument of model HDW-121.

[0055] In addition, at least one corrugated plate filler layer 107 with a predetermined thickness is provided in the second isolation zone to improve the oil-water separation effect.

[0056] In addition, the thickness of the corrugated plate packing layer 107 is between 10 and 80 cm.

[0057] In addition, a corrugated plate packing layer 107 is provided at the middle and lower part of the separation tank 1 and the lower part of the isolation protection tube 5. The outer diameter of the corrugated plate packing layer 107 is the same as the inner diameter of the separation tank 1 and the isolation protection tube 5, and the thickness is 20 cm.

[0058] The present application also provides a compact three-phase separation oil and gas recovery and metering device, which is provided with a vertical cylindrical separation tank 1, and a multiphase flow input port 101 is provided on the side of the upper middle portion of the separation tank 1.

[0059] In this example, as shown in FIG7 , the multiphase flow input port, i.e., the input port 101, is arranged along the horizontal tangent direction of the inner side of the separation tank 1 to guide the fluid input into the separation tank 1 to perform horizontal swirling motion along the inner side of the tank body. At this time, the liquid injection state in the separation tank 1 is as shown in FIG8 , and the liquid inlet position is near the total liquid level, which is particularly beneficial for gas-liquid separation in high-yield gas wells.

[0060] A free water output port, i.e., a first output port 102, is provided at the lower portion of the separation tank 1 and can be connected to the free water output pipeline; an emulsified oil output port 103, i.e., a second output port, is provided at the middle and upper portion of the separation tank 1 and can be connected to the emulsified oil output pipeline; a gas output port, i.e., a third output port 104, is provided at the top of the separation tank 1 and can be connected to the gas output pipeline; a free water control valve 201 is provided on the free water output pipeline 2 connected to the free water output port; an emulsified oil control valve 301 is provided on the emulsified oil output pipeline 3 connected to the emulsified oil output port; and a gas control valve 401 is provided on the gas output pipeline 4 connected to the gas output port.

[0061] An isolation protection tube 5 is provided above the interior of the separation tank 1. The isolation protection tube 5 is coaxially arranged with the separation tank 1. A vent is left at the top of the isolation protection tube 5 to maintain gas communication inside and outside the isolation protection tube 5; a first isolation zone (primary separation zone) for oil, water and gas is formed between the isolation protection tube 5 and the separation tank 1; the area inside the separation tank 1 except the first isolation zone constitutes a second isolation zone (secondary separation zone) for oil, water and gas that is basically undisturbed, which includes the inner side of the isolation protection tube 5 and the middle and lower space of the separation tank 1.

[0062] The emulsified oil output pipeline 3 is located inside the separation tank 1 and extends into the interior of the isolation protection cylinder 5. The sampling port of the emulsified oil output pipeline 3 is located below the liquid level and in the upper middle position of the isolation protection cylinder 5 to extract stable emulsified oil.

[0063] In this example, in order to further optimize the flow path of oil and water in the vertical separation tank 1 and improve the efficiency of oil-water separation, a corrugated plate packing layer 107 is provided in the middle and lower part of the vertical cylindrical separation tank 1 and the lower part of the isolation protection tube 5. The conventional corrugated plate packing increases the area of ​​oil-water exchange in the oil-water mixture passage, thereby improving the efficiency of oil-water separation in the same space. The outer diameter of the corrugated plate packing layer 107 is respectively adapted to the inner diameter of the vertical cylindrical separation tank 1 and the isolation protection tube 5, and the thickness is 20 cm. The 20 cm corrugated plate packing placed in the middle and lower part of the separation tank 1 increases the opportunities for emulsified oil and free water particles to combine with each other and improve the oil-water separation efficiency. At the same time, it suppresses the rapid movement of the oil-water mixture in the direction of sinking free water in the local area of ​​the horizontal plane, thereby improving the stable separation time of the overall oil-water mixture and ensuring that the free water exported is basically oil-free.

[0064] The 20cm corrugated plate filler placed at the bottom of the isolation protection tube 5 increases the chances of emulsified oil and free water particles combining with each other and improves the oil-water separation efficiency, while suppressing the rapid movement of the oil-water mixture in the direction of the floating emulsified oil in the local area of ​​the horizontal plane, thereby increasing the stable separation time of the overall emulsified oil, ensuring that the emulsified oil for external transmission basically does not contain large particles of free water, improving the overall oil-water separation efficiency in the secondary separation stable area, and better meeting the requirements of stable measurement and production of free water output from the drainage pipe 2 and emulsified oil output from the emulsified oil output pipeline 3.

[0065] In this example, the corrugated plate packing layer 107 plays an auxiliary role in improving efficiency. On the one hand, it increases the chance of oil-water contact separation and improves separation efficiency. On the other hand, it stabilizes the liquid surface of the emulsified oil and free water moving upward and downward, ensuring the stability of the emulsified oil and free water exported.

[0066] In this example, as shown in Figures 2 and 6 , an integrated oil-water interface and liquid level measurement assembly with segmented oil-water analysis function is used. The sensor in the oil-water interface and liquid level measurement assembly consists of a first electrode and a second electrode that are parallel to each other in the vertical direction and insulated from each other in the horizontal direction, wherein:

[0067] The first electrode is vertically composed of a group of tubular conductive segments, each of which is fixed and insulated with insulating material and electrically connected to the signal and data processing unit via wires located inside the segments. The first electrode is wrapped with a uniform outer insulating layer to form a combined rigid composite electrode, and each segment of the first electrode is electrically connected to the signal and data processing unit via a separate lead or a gate bus.

[0068] The second electrode accompanies the first electrode in the vertical direction and is electrically connected to the signal and data processing unit. The space between the first electrode and the second electrode is the measurement space of the sensor. A channel is left on the second electrode to facilitate the medium to enter and exit the measurement space.

[0069] In the spatial relationship between the first electrode and the second electrode, the second electrode partially or completely surrounds the first electrode in the horizontal direction; in the vertical direction, the outer conductive surface of the first electrode and the inner conductive surface of the second electrode are parallel to each other; each segment electrode of the first electrode and the corresponding part of the second electrode constitute a segmented sensor with oil-water analysis function, and the first electrode and the second electrode are isolated and fixed together by an insulating part, forming an integrated liquid level and oil-water interface monitoring device with segmented oil-water analysis function as a whole.

[0070] The advantages of this example are: 1. Strong anti-interference ability, accurate and stable interface measurement, which can ensure stable control of three-phase separation; 2. Compact structure, small lateral footprint, especially suitable for oil and gas metering and collection in small and medium-yield oil wells with limited lateral dimensions of the metering separation tank. When the measurement requirements for the water content of the emulsified oil are not high, the oil outlet of the emulsified oil pipeline can be directly aligned with one of the segment sensors to measure the water content, further simplifying the system.

[0071] The present application also provides a compact three-phase separation oil and gas recovery and metering device as shown in FIG3 , in which a vertical cylindrical separation tank 1 is provided, and a multiphase flow input port 101 is provided on the side of the upper middle portion of the separation tank 1, and the multiphase flow input port 101 is arranged along the horizontal tangent direction of the inner side of the separation tank 1, as shown in FIG7 , to guide the fluid input into the separation tank 1 to perform a horizontal swirling motion along the inner side of the tank body; a free water output port 102 is provided at the lower portion of the separation tank 1, and the free water output port 102 is connected to the free water output pipeline; An emulsified oil output port 103 is provided at the upper middle part of the separation tank 1, and the emulsified oil output port 103 is connected to the emulsified oil output pipeline; a gas output port 104 is provided at the top of the separation tank 1, and is connected to the gas output pipeline; a free water control valve 201 is provided on the free water output pipeline 2 connected to the free water output port 102; an emulsified oil control valve 301 is provided on the emulsified oil output pipeline 3 connected to the emulsified oil output port 103; and a gas control valve 401 is provided on the gas output pipeline 4 connected to the gas output port 104.

[0072] In this example, an isolation protection cylinder 5 is provided above the interior of the separation tank 1. The isolation protection cylinder 5 is coaxially arranged with the separation tank 1, and a vent is left on the top of the isolation protection cylinder 5 to maintain gas communication inside and outside the isolation protection cylinder 5; a first isolation zone for oil, water and gas is formed between the isolation protection cylinder 5 and the separation tank 1; a second isolation zone for oil, water and gas that is basically undisturbed is formed on the inner side of the isolation protection cylinder 5 and the middle and lower space of the separation tank 1; the emulsified oil output pipeline 3 is located inside the separation tank 1 and extends into the interior of the isolation protection cylinder 5, and the sampling port of the emulsified oil output pipeline 3 is located below the liquid surface and in the middle and upper position of the isolation protection cylinder 5 to extract stable emulsified oil.

[0073] Another embodiment of the present invention, as shown in Figure 1, Figure 2, or Figure 4, utilizes the integrated oil-water interface and liquid level measurement component based on the segmented electrical parameter measurement principle and the redundant control valve setting. In specific circumstances, such as when the liquid volume or gas volume exceeds the range of the corresponding flow meter, the emulsified oil control valve 301 is closed, and according to the method provided by the patent "Oil Content Measuring Method and Device for Oil Well Produced Liquid (201280001771.1)", the oil, water, and gas production is intermittently measured by regulating and jointly regulating the free water control valve 201 and the gas control valve 401. This is suitable for situations where the emulsion, free water, or associated gas exceeds the corresponding pipeline flow meter.

[0074] In the above embodiment, the integrated oil-water interface and liquid level measurement component may be a commercial multiphase oil-water interface meter of model HDW-121, for example.

[0075] The present invention also proposes a three-phase oil and gas separation recovery and metering method, comprising the following steps:

[0076] Step 1: Multiphase flow injection: Using the above-mentioned three-phase oil and gas separation and recovery metering device, a dynamic oil-water-gas multiphase flow is injected from the inlet 101 of the separation tank 1, and the multiphase flow is injected horizontally into the primary separation buffer zone, which is the space between the separation tank 1 and the isolation protection cylinder 5;

[0077] Step 2: Preliminary separation of multiphase flow: The multiphase flow injected into the separation tank 1 flows horizontally in the annular oil-water-gas primary isolation zone under the influence of its own kinetic energy and the differences in characteristics between the different phases of fluid, achieving gas-liquid separation. The separated gas moves upward and is output through the gas output port, i.e., the third output port 104, while the separated oil-water mixture moves downward uniformly, achieving preliminary oil-water separation.

[0078] Step 3: Secondary stabilization and separation of multiphase flow: The oil-water mixture after preliminary separation enters the secondary separation stabilization zone of oil, water and gas through the bottom of the isolation protection tube 5 for further stabilization and separation. The separated emulsified oil gradually rises in the secondary separation stabilization zone, and the water content gradually decreases. The separated free water gradually moves downward in the secondary separation stabilization zone, and the oil content becomes lower and lower. The separated emulsified oil extends into the sampling port inside the isolation protection tube 5 through the emulsified oil output pipeline 3, and is output to the outside through the emulsified oil output pipeline 3. The separated free water is output to the outside through the free water output port at the bottom, i.e., the first output port 102.

[0079] In step 3 of the present invention, with the help of monitoring of the oil-water interface and liquid level measuring components placed in the secondary separation stable zone, the positions of the oil-water interface and the total liquid level are controlled by jointly regulating the free water control valve 201, the emulsified oil control valve 301 and the gas control valve 401. The role of the oil-water interface and liquid level measuring components is to provide a basis for regulating the free water control valve 201, the emulsified oil control valve 301 and the gas control valve 401. When the oil-water interface is low, the opening of the free water control valve 201 is reduced to prevent the emulsified oil from flowing out through the free water pipeline; when the total liquid level is high, the opening of the gas control valve 401 is reduced to prevent the emulsified oil from flowing out through the associated gas pipeline; when the thickness of the emulsified oil layer is small, the opening of the emulsified oil control valve 301 is reduced to reduce the outflow rate of the emulsified oil through the emulsified oil pipeline. degree; the control principle is the same in reverse, which can ensure that the free water discharged from the drainage pipe 2 basically does not contain crude oil, and at the same time ensure that the sampling port 105 of the emulsified oil pipeline is always placed in a relatively stable emulsified oil layer, and when the oil-water measuring probe 601 on the oil-water analyzer array 6 or the oil-water analysis measuring instrument 303 provided on the emulsified oil output pipeline 3 is used to measure the oil content of the emulsified oil output, the measurement is kept accurate and stable; combined with the flow meter 202 on the free water pipeline 2, the flow meter 302 on the emulsified oil pipeline 3, and the gas flow meter 402 provided on the gas pipeline 4, the oil flow, water flow, and gas flow of the oil-water-gas multiphase flow can be obtained; if necessary, the diverted free water, emulsified oil, and associated gas can be separately transmitted through the free water pipeline 2, the emulsified oil pipeline 3, and the gas pipeline 4.

[0080] Compared with existing technologies, this invention offers the following advantages: Utilizing a vertical cylindrical structure, the device leverages the kinetic energy of the oil-water-gas multiphase flow and the differences in density between them to rationally guide the paths and directions of the oil, water, and gas flows. This allows for rapid separation of emulsified oil, free water, and associated gas within a very small space, creating a stable flow pattern. This enables continuous separation and measurement of the oil-water-gas three-phase flow, particularly beneficial for gas-liquid separation in high-yield gas wells. This ensures stable and accurate measurement of oil and gas production, providing an important tool for the informatization and intensification of oilfield production. The vertical structure vertically extends the stable zone for secondary oil-water-gas separation, reducing the difficulty of controlling the liquid level and oil-water interface, simplifying the control system, and improving the efficiency and quality of oil-water control. The device boasts a compact structure, small size, and low cost. Compared with horizontal separation tanks with comparable three-phase separation capabilities, it saves 60%-90% of floor space, offering a high cost-effectiveness and suitable for widespread adoption. Furthermore, it enables both continuous measurement of oil, water, and gas, and intermittent measurement under specific circumstances.

[0081] This application also provides the following notes:

[0082] Note 1. A vertical separation tank 1, comprising:

[0083] An input port 101 is provided at the upper middle portion of the separation tank 1 and is used to introduce a multiphase flow into the metering separation tank 1; the multiphase flow includes a mixture of free water, emulsified oil and gas;

[0084] The first output port 102 is provided at the bottom of the separation tank 1 and is used to output the separated free water;

[0085] The second output port 103 is provided in the middle of the separation tank 1 and is used to output the separated emulsified oil;

[0086] The third output port 104 is provided at the top of the separation tank 1 and is used to output the separated gas. The third output port 104 is characterized in that the separation tank 1 includes a first isolation zone and a second isolation zone.

[0087] The first isolation zone is used to receive the three-phase flow input from the input port 101, buffer it, and mainly achieve gas-liquid separation, and discharge the separated gas and the separated oil-water mixture into the second isolation zone through its first opening and second opening respectively;

[0088] Among them, the second isolation zone is used to accommodate the separated gas from the first isolation zone and stabilize the oil-water mixture from the first isolation zone and mainly realize oil-water separation, and can discharge the separated water, oil and gas respectively through the first output port 102, the second output port 103 and the third output port 104.

[0089] Note 2. According to the vertical separation tank 1 described in Note 1, the separation tank 1 is configured so that the three-phase flow entering the first isolation zone performs a circulation motion therein.

[0090] Note 3. According to the vertical separation tank 1 described in Note 1, an isolation protection tube 5 is provided inside the separation tank 1, which has an upper opening and a lower opening connected to the separation tank 1, wherein the isolation protection tube 5 is basically coaxially arranged with the separation tank 1, and its cross-section basically forms a concentric ring, and the concentric annular space between the outer wall of the isolation protection tube 5 and the relative inner wall of the separation tank 1 forms the first isolation zone, and the space inside the separation tank below the isolation protection tube 5, the internal space of the isolation protection tube 5 and the space inside the separation tank above the isolation protection tube 5 form the second isolation zone.

[0091] Note 4. According to the vertical separation tank 1 described in Note 1, an isolation protection tube 5 is provided inside the separation tank 1, which has an upper opening and a lower opening connected to the separation tank 1, wherein the isolation protection tube 5 is off-axis from the vertical separation tank, and its cross-section forms an eccentric ring, and the internal space of the isolation protection tube 5 forms the first isolation zone, and the space inside the separation tank at the lower part of the isolation protection tube 5, the eccentric annular space formed by the outer wall of the isolation protection tube 5 and the inner wall of the opposite separation tank 1, and the space inside the separation tank at the upper part of the isolation protection tube 5 form the second isolation zone.

[0092] Note 5. The vertical separation tank 1 according to one of Notes 1-4 further includes a measuring device 6, which is arranged in the second isolation zone and extends longitudinally along the second isolation zone, and is used to measure the oil-water interface and / or liquid level position and / or output the water content information of the emulsified oil.

[0093] Note 6. According to the vertical separation tank 1 described in any one of Notes 1-4, at least one layer of corrugated plate filler layer 107 with a predetermined thickness is provided in the second isolation zone to improve the oil-water separation effect.

[0094] Note 7. According to the vertical separation tank 1 described in Note 6, the thickness of the corrugated plate packing layer 107 is between 10 and 80 cm.

[0095] Note 8. According to the vertical separation tank 1 described in Note 3, a layer of corrugated plate packing layer 107 is respectively provided in the middle and lower part of the separation tank 1 and the lower part of the isolation protection tube 5. The outer diameter of the corrugated plate packing layer 107 is respectively adapted to the inner diameter of the separation tank 1 and the isolation protection tube 5, and the thickness is 20 cm.

[0096] Note 9. In the vertical separation tank 1 according to Note 2, the circulation motion includes a circulation motion in the horizontal direction.

[0097] Note 10. A three-phase oil and gas separation, recovery and metering device, provided with a vertical separation tank body 1 as described in any one of Notes 1-8, wherein the first output port 102 is connected to the free water output pipeline; the second output port 103 is connected to the emulsified oil output pipeline; the third output port 104 is connected to the gas output pipeline; a free water control valve 201 is provided on the free water output pipeline 2 connected to the first output port 102; an emulsified oil control valve 301 is provided on the emulsified oil output pipeline 3 connected to the second output port 103; a gas control valve 401 is provided on the gas output pipeline 4 connected to the third output port 104, the emulsified oil output pipeline 3 is located inside the separation tank 1 and extends into the interior of the second isolation zone, and the sampling port of the emulsified oil output pipeline 3 is located below the liquid surface and in the upper middle position of the second isolation zone to extract stable emulsified oil.

[0098] Note 11. According to the three-phase oil and gas separation and recovery metering device described in Note 10, the separated free water is measured by arranging a water flow meter 202 on the drainage pipe 2; the separated associated gas is measured by arranging a gas flow meter 402 on the gas output pipe 4; the oil and water contained in the emulsified oil are measured by arranging an emulsified oil flow meter 302 and an oil-water analyzer 303 on the emulsified oil output pipe 3; or, the oil and water contained in the emulsified oil are measured by arranging an emulsified oil flow meter 302 on the emulsified oil output pipe 3 and an in-tank oil-water measuring unit 32 in the tank body; or, the oil and water contained in the emulsified oil are measured by arranging a mass flow meter on the emulsified oil output pipe 3; the total of the free water flowing through the drainage pipe 2 and the water measured in the emulsified oil pipe 3 is the amount of water in the oil-water-gas three-phase flow.

[0099] Note 12. The three-phase oil and gas separation and recovery metering device according to Note 10 is also provided with a data processing and control unit 7, which is electrically connected to the control valves 201, 301, 401, flow meters 202, 302, 402, oil-water analyzer 303, oil-water interface and liquid level measuring device 6 or oil-water interface meter 61 and liquid level meter 62, temperature transmitter 105, and pressure transmitter 106.

[0100] Note 13. A three-phase oil and gas separation and recovery measurement method comprising the following steps:

[0101] Step 1: Multiphase flow injection: Using the above-mentioned three-phase oil and gas separation and recovery metering device, a dynamic oil-water-gas multiphase flow is injected from the inlet 101 of the separation tank 1, and the multiphase flow is injected horizontally into the primary separation buffer zone, which is the space between the separation tank 1 and the isolation protection cylinder 5;

[0102] Step 2: Preliminary separation of multiphase flow: The multiphase flow injected into the separation tank 1 flows horizontally in the annular oil-water-gas primary isolation zone under the influence of its own kinetic energy and the differences in characteristics between the different phases of fluid, achieving gas-liquid separation. The separated gas moves upward and is output through the gas output port, i.e., the third output port 104, while the separated oil-water mixture moves downward uniformly, achieving preliminary oil-water separation.

[0103] Step 3: Secondary stabilization and separation of multiphase flow: The oil-water mixture after preliminary separation enters the secondary separation stabilization zone of oil, water and gas through the bottom of the isolation protection tube 5 for further stabilization and separation. The separated emulsified oil gradually rises in the secondary separation stabilization zone, and the water content gradually decreases. The separated free water gradually moves downward in the secondary separation stabilization zone, and the oil content becomes lower and lower. The separated emulsified oil extends into the sampling port inside the isolation protection tube 5 through the emulsified oil output pipeline 3, and is output to the outside through the emulsified oil output pipeline 3. The separated free water is output to the outside through the free water output port at the bottom, i.e., the first output port 102.

[0104] 14. According to the three-phase oil and gas separation recovery metering method described in Note 13, in step 3, with the help of the monitoring of the oil-water interface and liquid level measuring component placed in the secondary separation stable zone, the position of the oil-water interface and the total liquid level is controlled by jointly regulating the free water control valve 201, the emulsified oil control valve 301 and the gas control valve 401. The role of the oil-water interface and liquid level measuring component is to provide a basis for the regulation of the free water control valve 201, the emulsified oil control valve 301 and the gas control valve 401. When the oil-water interface is low, the opening of the free water control valve 201 is reduced to prevent the emulsified oil from flowing out through the free water pipeline; when the total liquid level is high, the opening of the gas control valve 401 is reduced to prevent the emulsified oil from flowing out through the associated gas pipeline; when the thickness of the emulsified oil layer is small, the opening of the emulsified oil control valve 301 is reduced to reduce the emulsified oil. The outflow rate of oil through the emulsified oil pipeline; the control principle is the same in reverse, ensuring that the free water discharged from the drainage pipeline 2 basically does not contain crude oil, and at the same time ensuring that the sampling port 105 of the emulsified oil pipeline is always placed in a relatively stable emulsified oil layer, when using the oil-water measuring probe 601 on the oil-water analyzer array 6 or the oil-water analysis measuring instrument 303 provided on the emulsified oil output pipeline 3 to measure the oil content of the outgoing emulsified oil, the measurement is kept accurate and stable; combined with the flow meter 202 provided on the free water pipeline 2, the flow meter 302 on the emulsified oil pipeline 3, and the gas flow meter 402 provided on the gas pipeline 4, the oil flow, water flow, and gas flow of the oil-water-gas multiphase flow can be obtained; if necessary, the diverted free water, emulsified oil, and associated gas can also be diverted and transported through the free water pipeline 2, the emulsified oil pipeline 3, and the gas pipeline 4.

[0105] Although several specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present invention. Certain features described in the context of separate embodiments can also be implemented in combination in a single embodiment. Relatively, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0106] The above description is only a preferred embodiment of the present invention and an explanation of the technical principles used. In the above specific embodiments, for example, the separation tank 1 and the isolation protection cylinder 5 are circular tanks or circular cylinders, but tanks or cylinders of other shapes are also possible, such as oval and square. Those skilled in the art should understand that the scope of disclosure involved in the present invention is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concepts. For example, the above features are replaced with the technical features with similar functions disclosed in the present invention (but not limited to).

Claims

1. A vertical separation tank (1), comprising: An input port (101), arranged in the upper middle part of the separation tank (1), for introducing a multiphase flow into the metering separation tank (1); the multiphase flow includes a mixture of free water, emulsified oil and gas; A first output port (102), arranged at the bottom of the separation tank (1), for outputting the separated free water; A second output port (103), arranged in the middle part of the separation tank (1), for outputting the separated emulsified oil; A third output port (104), arranged at the top of the separation tank (1), for outputting the separated gas, characterized in that the separation tank (1) includes a first isolation area and a second isolation area: Wherein, the first isolation area is used for receiving the three-phase flow input by the input port (101), buffering it and mainly realizing gas-liquid separation, and discharging the separated gas and the oil-water mixture to be separated through its first opening and second opening into the second isolation area respectively; Wherein, the second isolation area is used for accommodating the separated gas from the first isolation area, stabilizing the oil-water mixture from the first isolation area and mainly realizing oil-water separation, and can discharge the separated water, oil and gas through the first output port (102), the second output port (103) and the third output port (104) respectively.

2. The vertical separation tank (1) according to claim 1, characterized in that, The separation tank (1) is arranged such that the three-phase flow entering the first isolation area circulates therein.

3. The vertical separation tank (1) according to claim 1, characterized in that, An isolation protection cylinder (5) is arranged inside the separation tank (1), which has an upper opening and a lower opening communicating with the separation tank (1). Wherein, the isolation protection cylinder (5) is arranged substantially coaxially with the separation tank (1), and its cross-section substantially forms a concentric ring. The concentric annular space between the outer wall of the isolation protection cylinder (5) and the inner wall of the opposite separation tank (1) forms the first isolation area, and the inner space of the separation tank below the lower part of the isolation protection cylinder (5), the inner space of the isolation protection cylinder (5) and the inner space of the separation tank above the upper part of the isolation protection cylinder (5) form the second isolation area.

4. The vertical separation tank (1) according to claim 1, characterized in that An isolation protection cylinder (5) is arranged inside the separation tank (1), which has an upper opening and a lower opening communicating with the separation tank (1). Wherein, the isolation protection cylinder (5) is arranged off-axis with the vertical separation tank, and its cross-section forms an eccentric ring. The inner space of the isolation protection cylinder (5) forms the first isolation area, and the inner space of the separation tank below the lower part of the isolation protection cylinder (5), the eccentric annular space formed by the outer wall of the isolation protection cylinder (5) and the inner wall of the opposite separation tank (1), and the inner space of the separation tank above the upper part of the isolation protection cylinder (5) form the second isolation area.

5. The vertical separation tank (1) according to any one of claims 1 to 4, characterized in that, It further includes a measuring device (6), which is arranged in the second isolation area and extends longitudinally along the second isolation area, for measuring the oil-water interface and / or the liquid level position and / or outputting the water content information of the emulsified oil.

6. The vertical separation tank (1) according to any one of claims 1-4, characterized in that, In the second isolation area, at least one layer of corrugated plate packing layer (107) with a predetermined thickness is provided to improve the oil-water separation effect.

7. The vertical separation tank (1) according to claim 6, characterized in that, The thickness of the corrugated plate packing layer (107) is between 10 and 80 cm.

8. The vertical separation tank (1) according to claim 3, characterized in that, One layer of corrugated plate packing layer (107) is provided at the middle and lower part of the separation tank (1) and the lower part of the isolation protection cylinder (5). The outer diameters of the corrugated plate packing layers (107) are respectively adapted to the inner diameters of the separation tank (1) and the isolation protection cylinder (5), and the thickness of each is 20 cm.

9. The vertical separation tank (1) according to claim 2, characterized in that, The circulating flow motion includes the circulating flow motion in the horizontal direction.

10. The vertical separation tank (1) according to claim 5, characterized in that The measuring device (6) includes an integrated oil-water interface and liquid level measuring component with a segmented oil-water analysis function.

11. A three-phase oil-gas separation, recovery and metering device, characterized in that, There is provided a vertical separation tank body (1) as described in any one of claims 1-8. Among them, the first output port (102) is connected to the free water output pipeline; the second output port (103) is connected to the emulsified oil output pipeline; the third output port (104) is connected to the gas output pipeline; a free water control valve (201) is provided on the free water output pipeline (2) connected to the first output port (102); an emulsified oil control valve (301) is provided on the emulsified oil output pipeline (3) connected to the second output port (103); a gas control valve (401) is provided on the gas output pipeline (4) connected to the third output port (104). The pipeline of the emulsified oil output pipeline (3) located inside the separation tank (1) extends into the interior of the second isolation area, and the sampling port of the emulsified oil output pipeline (3) is located below the liquid level and at the middle and upper position of the second isolation area so as to extract stable emulsified oil.

12. The three-phase oil-gas separation, recovery and metering device according to claim 11, wherein By providing a water flowmeter (202) on the drainage pipeline (2), the separated free water is measured; by providing a gas flowmeter (402) on the gas output pipeline (4), the associated gas separated is measured; by providing an emulsified oil flowmeter (302) and an oil-water analyzer (303) on the emulsified oil output pipeline (3), the oil and water contained in the emulsified oil are measured; or, by providing an emulsified oil flowmeter (302) on the emulsified oil output pipeline (3) and providing an in-tank oil-water measuring unit (32) inside the tank, the oil and water contained in the emulsified oil are measured; or, by providing a mass flowmeter on the emulsified oil output pipeline (3), the oil and water contained in the emulsified oil are measured; the total amount of water in the oil-water-gas three-phase flow is the sum of the free water flowing through the drainage pipeline (2) and the water measured in the emulsified oil pipeline (3).

13. The three-phase oil-gas separation, recovery and metering device according to claim 11, characterized in that, There is also provided a data processing and control unit (7), which is electrically connected to the control valves (201), (301), (401), flowmeters (202), (302), (402), oil-water analyzer (303), oil-water interface and liquid level measuring device (6) or oil-water interface meter (61) and liquid level meter (62), temperature transmitter (105), pressure transmitter (106).

14. A three-phase oil-gas separation, recovery and metering method, characterized in that, It includes the following steps: Step 1: Multiphase flow injection: Using the above-mentioned three-phase oil-gas separation, recovery and metering device, the dynamic oil-water-gas multiphase flow is injected from the input port (101) of the separation tank (1), and the multiphase flow is injected into the primary separation buffer zone in the horizontal direction. The primary separation buffer zone is the space between the separation tank (1) and the isolation protection cylinder (5). Step 2: Preliminary separation of multiphase flow: The multiphase flow injected into the separation tank (1) flows horizontally in the annular oil-water-gas primary isolation zone under the action of its own kinetic energy and the characteristic differences between different-phase fluids. On the one hand, gas-liquid separation is achieved. The separated gas moves upward and is exported through the gas outlet, i.e., the third outlet (104). The separated oil-water mixture moves downward evenly for preliminary oil-water separation. Step 3: Secondary stabilization and separation of multiphase flow: The oil-water mixture after preliminary separation enters the secondary separation and stabilization zone of oil-water-gas through the lower part of the isolation protection cylinder (5) for further stabilization and separation. The separated emulsified oil gradually rises in the secondary separation and stabilization zone, and the water content gradually decreases. The separated free water gradually moves downward in the secondary separation and stabilization zone, and the oil content becomes lower and lower. The separated emulsified oil passes through the sampling port where the emulsified oil output pipeline (3) extends into the isolation protection cylinder (5) and is exported through the emulsified oil output pipeline (3). The separated free water is exported through the lower free water outlet, i.e., the first outlet (102).

15. The three-phase oil-gas separation, recovery and metering method according to claim 14, wherein In Step 3, with the monitoring of the oil-water interface and liquid level measurement component placed in the secondary separation and stabilization zone, the positions of the oil-water interface and the total liquid level are controlled by jointly regulating the free water control valve (201), the emulsified oil control valve (301), and the gas control valve (401). The role of the oil-water interface and liquid level measurement component is to provide a basis for the regulation of the free water control valve (201), the emulsified oil control valve (301), and the gas control valve (401). When the oil-water interface is relatively low, the opening of the free water control valve (201) is reduced to prevent the emulsified oil from flowing out through the free water pipeline; when the total liquid level is relatively high, the opening of the gas control valve (401) is reduced to prevent the emulsified oil from flowing out through the associated gas pipeline; when the thickness of the emulsified oil layer is relatively small, the opening of the emulsified oil control valve (301) is reduced to reduce the outflow rate of the emulsified oil through the emulsified oil pipeline; the regulation principle for the opposite situation is the same, ensuring that the free water discharged from the drainage pipeline (2) is basically free of crude oil, and at the same time ensuring that the sampling port (105) of the emulsified oil pipeline is always placed in a relatively stable emulsified oil layer. When measuring the oil content of the exported emulsified oil with the oil-water measurement probe (601) on the oil-water analyzer array (6) or the oil-water analysis and measurement instrument (303) installed on the emulsified oil output pipeline (3), the measurement is kept accurate and stable; combined with the flowmeter (202) installed on the free water pipeline (2), the flowmeter (302) installed on the emulsified oil pipeline (3), and the gas flowmeter (402) installed on the gas transmission pipeline (4), the oil flow rate, water flow rate, and gas flow rate of the oil-water-gas multiphase flow can be obtained; if necessary, the separated free water, emulsified oil, and associated gas can also be separately transported through the free water pipeline (2), the emulsified oil pipeline (3), and the gas transmission pipeline (4).

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