Foundation separation unit and in-situ oil-water separation device using the same

Abstract

The application discloses a basic separation unit and an on-site oil-water separation device using the same. Each basic separation unit is suitable for oil-water separation in oil fields and / or refineries by modular assembly. The unit is used as a gravity settling module and comprises a tank body provided with a gas outlet at the top and a sand outlet at the bottom. A liquid inlet is arranged on the upper part of the side wall of the tank body, and a water outlet is arranged on the lower part of the side wall. An oil outlet is arranged above the liquid inlet. A sensor is arranged at a height between the liquid inlet and the oil outlet in the tank body, and is used for sensing whether the oil phase to be flowed out in the oil-water mixture at the height of the sensor reaches a preset value. A connecting inclined pipe is in communication with the water outlet at one end and in communication with the liquid inlet of the next basic separation unit at the other end. The modular on-site oil-water separation device can be modularly assembled according to the properties of oil-water in the field, can not only separate a large amount of oil-water continuously, but also can effectively reduce the floor area of the equipment.

Description

Technical Field

[0001] This invention relates to the field of oil-water separation technology in petroleum and petrochemical industries, and particularly to a basic separation unit applied in oil fields or refineries and an on-site oil-water separation device using the unit. Background Technology

[0002] Oil-water separation plays a crucial role in the petroleum and petrochemical industries. Due to the strong mechanical disturbances or large amounts of chemical substances present during oil extraction or petrochemical production, crude oil or distillate oil and liquid water form a stable emulsion. To obtain a pure product, it is often necessary to demulsify and separate the oil-water emulsion. Generally, oil-water demulsification can be broadly divided into chemical and physical methods. Currently, the most widely used physical oil-water separation method in industry is gravity sedimentation. This method involves placing the oil-water emulsion in a container and relying on gravity to separate the oil and water. This method is simple to operate, but it is time-consuming, and when processing large quantities of oil-water emulsions, it often requires large-volume sedimentation tanks, which not only limit the processing capacity but also require a large floor space. For oil-water separation problems requiring large-scale continuous processing with limited available operating space, gravity sedimentation separation is difficult.

[0003] In industrial practice, there are also various physical demulsification methods such as electro-demulsification, coalescing medium demulsification, microwave demulsification, supergravity demulsification, and multi-field coupling demulsification. Although these demulsification methods can achieve good oil-water separation results, they have certain limitations on the properties of the oil-water emulsion being processed. Different oil-water properties often require certain pretreatment processes, which limits the widespread use of a specific oil-water separation device.

[0004] Furthermore, for oilfields or refineries, the oil-water emulsions produced from wellheads or reaction towers often contain large amounts of wastewater or waste oil. Moreover, the locations of some oilfield wellheads or refineries are often far from combined stations or water treatment plants. Directly transporting the emulsion to these facilities often results in significant waste, and the product transportation efficiency is very low due to the wastewater or waste oil present in the emulsion. The industry needs to perform coarse separation of oil-water emulsions on-site at wellheads, transfer stations, or refineries to remove as much wastewater or waste oil as possible.

[0005] Because the available area at oil fields or refineries is generally small, it is difficult to install large gravity settling equipment, resulting in a small processing capacity. In addition, the properties of oil and water flowing from different wellheads and different reactors often vary greatly. Using a uniform oil-water separation device is difficult to meet the separation requirements under different conditions, while using different equipment will cause processing difficulties and increase costs.

[0006] Therefore, there is an urgent need for a modular oil-water demulsification and separation device that can be applied to oil fields or refineries, effectively, continuously separate different oil-water emulsions in large quantities, and has a small footprint.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a basic separation unit for use in oil fields or refineries and an on-site oil-water separation device using this unit. The separation equipment can be modularly assembled according to the properties of oil and water on site, which can not only perform large-scale and continuous oil-water separation, but also effectively reduce the footprint of the equipment.

[0009] To achieve the above objectives, according to a first aspect of the present invention, the present invention provides a basic separation unit, each basic separation unit being modularly assembled and suitable for oil-water separation in oil fields and / or refineries. This unit is used as a gravity settling module and includes: a tank body with an air outlet at the top and a sand outlet at the bottom; an inlet at the upper part of the tank body side wall and a water outlet at the lower part of the tank body side wall; an oil outlet above the inlet; a sensor disposed at a height between the inlet and the oil outlet within the tank body, used to sense whether the oil phase to be discharged from the oil-water mixture at the sensor height has reached a preset value; and a connecting inclined tube, one end of which is connected to the water outlet and the other end of which is connected to the inlet of the next basic separation unit.

[0010] Furthermore, in the above technical solution, the tank body may be equipped with an insulation jacket; and a heater may be installed on the outside of the connecting inclined tube.

[0011] Furthermore, in the above technical solution, flow control valves can be installed at the liquid inlet, water outlet, and oil outlet.

[0012] Furthermore, in the above technical solution, a coalescing medium and / or electrodes can be installed between the liquid inlet and the water outlet inside the tank.

[0013] Furthermore, in the above technical solution, when a coalescing medium is provided between the inlet and the outlet, the basic separation unit is used as a coalescing separation module; when an electrode is provided between the inlet and the outlet, the basic separation unit is used as an electro-separation module; and when a coalescing medium and an electrode are provided between the inlet and the outlet, the basic separation unit is used as a multi-field collaborative separation module.

[0014] Furthermore, in the above technical solution, the coalescing medium bed can be plate type, packing type or filter element type.

[0015] Furthermore, in the above technical solution, when the liquid to be treated is an oil-in-water emulsion, the coalescing medium can be polytetrafluoroethylene or polypropylene, etc.; when the liquid to be treated is a water-in-oil emulsion, the coalescing medium can be glass fiber, metal fiber or quartz sand, etc.

[0016] Furthermore, in the above technical solution, the electrode can be a rod-shaped electrode or an electrode plate, etc.

[0017] Furthermore, in the above technical solution, when the basic separation unit is used as a multi-field collaborative separation module, the electrodes can be inserted into the coalescing medium bed.

[0018] According to a second aspect of the present invention, the present invention provides an on-site oil-water separation device, including any of the aforementioned basic separation units. The number of basic separation units can be multiple and arranged in a compact manner. The number of basic separation units used and the types of modules are combined and matched according to the properties of the oil and water to be separated.

[0019] Furthermore, in the above technical solution, when three basic separation units are used, the compact layout can be designed as a horizontal layout or a triangular layout; when four basic separation units are used, the compact layout can be designed as a square layout.

[0020] Furthermore, in the above technical solution, when the liquid to be treated is oily wastewater and the aqueous phase contains salt, the basic separation unit can be a coalescing media module and set in multiple stages. The multi-stage setting can specifically be: the first stage is set with polytetrafluoroethylene coalescing inclined plates, the second stage is set with polypropylene microsphere packing, and the third stage is set with woven polyethylene fibers.

[0021] Furthermore, in the above technical solution, when the fluid to be treated is produced fluid from the oilfield, the on-site oil-water separation device is set up at the oilfield metering station; in the early stage of oilfield development and when the oil-water emulsion is mainly a water-in-oil emulsion, a three-stage basic separation unit can be set up, all of which are coalescing separation modules, and all three stages are filled with hydrophilic coalescing media; in the middle stage of oilfield development, a three-stage basic separation unit can be set up, all of which are coalescing separation modules, of which the first two stages can be filled with hydrophilic coalescing media and the third stage can be filled with oleophilic coalescing media; in the later stage of oilfield development, a two-stage basic separation unit can be set up, both of which are coalescing separation modules, and both stages are filled with oleophilic coalescing media.

[0022] Furthermore, in the above technical solution, when the fluid to be treated is oilfield produced fluid and on-site water separation of the produced oil is required, the on-site oil-water separation device is used in reverse, with the original sand outlet set as the gas outlet, the original gas outlet set as the sand outlet, the original water outlet set as the oil outlet, and the original oil outlet set as the water outlet. The separated water is discharged from the water outlet, and the produced oil continues to enter the next stage basic separation unit along the connecting inclined pipe.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1) This invention uses a basic separation unit as the smallest unit and sets internal components in the basic separation unit to construct separation modules with different physical separation types. The modular combination of separation equipment can be carried out according to the oil and water properties on the oilfield or refinery site. This not only enables multi-stage separation, making the oil and water separation effect better and enabling large-scale and continuous oil and water separation, but also effectively reduces the footprint of the equipment.

[0025] 2) The on-site oil-water separation device of the present invention can provide targeted module combination methods for different oil-water conditions, and is more universal and applicable than existing devices;

[0026] 3) This invention connects the various modules in series by connecting inclined tubes, making it easier to install and disassemble. It can be dynamically adjusted according to the condition of the liquid to be treated on site, with short downtime and simple operation.

[0027] 4) When the fluid to be treated is oilfield produced fluid, the water content of the produced fluid gradually increases with the increase of the extraction time. Therefore, by using the modular device of the present invention, the number and type of modules can be adjusted in the early, middle and late stages of extraction, thus making it more adaptable. Dynamic treatment of the fluid to be treated can effectively improve the processing volume and processing capacity, and reduce the subsequent oil and water treatment load.

[0028] 5) When the produced fluid in the oilfield needs to be separated into water on-site, the present invention can use the on-site oil-water separation device inverted. By swapping the openings of each tank, the separated water is discharged from the outlet, and the produced oil continues to enter the next stage basic separation unit along the connecting inclined pipe. By simply inverting the device that was originally in normal use, the original continuous wastewater treatment can be transformed into continuous crude oil treatment. The method is simple, requires no additional processing or manufacturing, and can minimize operating costs.

[0029] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0030] Figure 1 is a schematic diagram of the basic separation unit of the present invention (wherein) Figure 1-A Used as a gravity settlement module; Figure 1-B Used as a coalescing and separation module; Figure 1-C Used as an electrical separation module; Figure 1-D (Used as a multi-field collaborative separation module).

[0031] Figure 2This is a schematic diagram of the first combined embodiment of the on-site oil-water separation device of the present invention (the four-stage separation uses a gravity settling module, a coalescence separation module, an electrostatic separation module, and a multi-field synergistic separation module, respectively).

[0032] Figure 3 This is a schematic diagram of the second combined embodiment of the on-site oil-water separation device of the present invention (all three stages use gravity settling modules and the connecting inclined tubes do not use heaters).

[0033] Figure 4 This is a schematic diagram of the third combined embodiment of the on-site oil-water separation device of the present invention (all three stages use coalescence separation modules).

[0034] Figure 5 This is a schematic diagram of the fourth combined implementation of the on-site oil-water separation device of the present invention (all three stages use multi-field collaborative separation modules).

[0035] Figure 6 This is a schematic diagram of the fifth combined embodiment of the on-site oil-water separation device of the present invention (the basic separation unit of the present invention is inverted and combined for use, which is suitable for situations where the liquid to be treated is oilfield produced fluid and on-site water separation of produced oil is required).

[0036] Figure 7 is a top view of the arrangement of the basic separation units of the on-site oil-water separation device of the present invention (wherein) Figure 7-A This illustrates a square arrangement. Figure 7-B This illustrates the horizontal arrangement. Figure 7-C (This shows a triangular arrangement.)

[0037] Explanation of key figure labels:

[0038] 1-Basic separation unit, 1A-Gravity sedimentation module, 1B-Coalescing separation module, 1C-Electrostatic separation module, 1D-Multi-field synergistic separation module, 10-Tank body, 11-Gas outlet, 12-Sand outlet, 13-Liquid inlet, 14-Oil outlet, 15-Water outlet, 16-Coalescing medium bed, 17-Electrode, 2-Sensor, 3-Connecting inclined tube, 31-Heater.

[0039] 100 - First on-site oil-water separator, 200 - Second on-site oil-water separator, 300 - Third on-site oil-water separator, 400 - Fourth on-site oil-water separator, 500 - Fifth on-site oil-water separator. Detailed Implementation

[0040] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0041] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0042] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0043] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0044] As shown in Figure 1, this invention provides a basic separation unit 1 for oil-water separation (i.e., on-site oil-water separation) in oil fields and / or refineries. Each basic separation unit 1 can be assembled in a modular fashion according to site requirements and the properties of the oil and water to perform oil-water separation. The most basic basic separation unit can be used as a gravity settling module 1A (see reference). Figure 1-AThe system includes a tank 10, a sensor 2, and a connecting inclined tube 3. The tank 10 has an air outlet 11 at the top and a sand outlet 12 at the bottom; a liquid inlet 13 on the upper part of the side wall and a water outlet 15 on the lower part of the side wall; and an oil outlet 14 above the liquid inlet 13. The sensor 2 is positioned at a height between the liquid inlet 13 and the oil outlet 14 within the tank 10 to sense whether the oil phase to be discharged from the oil-water mixture at the sensor height has reached a preset value. By placing the sensor 2 between the liquid inlet and the oil outlet, the oil phase flowing out of the oil outlet can be ensured to meet the expected index by sensing the oil-water content at the sensor, preventing unseparated oil phase from flowing out of the oil outlet 14. One end of the connecting inclined tube 3 is connected to the water outlet 15, and the other end is connected to the liquid inlet 13 of the next basic separation unit 1. Specifically, the tank 10 can be a cylindrical metal tank, serving as the main outer shell of the basic separation unit 1. The tank 10 has an internal insulation layer for temperature control. The separated gas phase can flow out from the gas outlet 11; the separated solid particles can be discharged from the sand outlet 12; the oil outlet 14, liquid inlet 13, and water outlet 15 are arranged sequentially from top to bottom along both sides of the tank body 10. After gravity settling, the separated oil phase can be discharged from the oil outlet 14, the oil-water emulsion to be separated can flow into the basic separation unit 1 from the liquid inlet 13, and the separated water phase after gravity settling can be discharged from the water outlet 15. Flow control valves are installed on all openings on the tank body 10. Furthermore, a heater 31 can be installed outside the connecting inclined tube 3. The heater can adopt various heating forms such as electric heating, co-current / counter-current heat exchange, combustion heating, and radiation heating. The specific heater type can be determined according to the construction site conditions.

[0045] like Figure 1-A The diagram shows a basic module of the basic separation unit, which is used in this invention as gravity settling module 1A. This invention modifies the module's function by adding or removing internal components; in addition to gravity settling module 1A, it also includes coalescence separation module 1B (see reference). Figure 1-B ), Electrical separation module 1C (reference) Figure 1-C ) and multi-field collaborative separation module 1D (reference) Figure 1-D By combining various modules, the goal is to achieve efficient separation of oil-water emulsions with different properties, enabling on-site oil-water separation in oil fields or refineries, thus overcoming the shortcomings of existing on-site oil-water separation equipment, such as small processing capacity, long processing time, and poor processing effect.

[0046] Further as Figures 1-B to 1-D As shown, in order to construct more types of basic separation units, this invention, based on gravity settling module 1A, sets a coalescing medium and / or electrodes between the inlet and outlet of the tank, thereby obtaining... Figure 1-B The shown coalescence separation module 1B (which can achieve coupled demulsification and separation of gravity field and coalescence field) is configured by setting a coalescence medium bed 16 between the inlet 13 and the outlet 15, and can also obtain... Figure 1-C The electro-separation module 1C shown (which can achieve demulsification separation by coupling a gravity field and an electric field) has an electrode 17 placed between the inlet 13 and the outlet 15, and can also obtain... Figure 1-D The multi-field synergistic separation module 1D shown (i.e., coupled demulsification separation of gravity field + coalescence field + electric field) is used when the basic separation unit 1 is used as the multi-field synergistic separation module 1D, with electrode 17 inserted in the coalescence medium bed 16. In summary, when the coalescence medium bed 16 is placed between the inlet 13 and the outlet 15, the basic separation unit is used as the coalescence separation module 1B; when electrode 17 is placed between the inlet 13 and the outlet 15, the basic separation unit is used as the electrostatic separation module 1C; when both the coalescence medium and electrode are placed between the inlet 13 and the outlet 15, the basic separation unit is used as the multi-field synergistic separation module 1D. This invention is not limited to these; in addition to constructing the aforementioned modules, a magnetic plate can be added inside the tank 10 as needed to achieve electromagnetic demulsification; a stirring device can also be added to achieve ultragravity oil-water separation, etc., which will not be detailed here.

[0047] Furthermore, preferably but not limitingly, the coalescing medium bed can be plate-type, packing-type, or filter-type. Additionally, different types of coalescing media can be selected based on the properties of the liquid to be treated. For example, when the liquid to be treated is an oil-in-water emulsion, the coalescing medium can be polytetrafluoroethylene or polypropylene; when the liquid to be treated is a water-in-oil emulsion, the coalescing medium can be glass fiber, metal fiber, or quartz sand. The electrodes in the aforementioned electro-separation module 1C can be rod-shaped electrodes or electrode plates.

[0048] This invention also provides an in-situ oil-water separation device using the aforementioned basic separation units. In this device, multiple basic separation units are arranged in a compact manner, and the number and type of basic separation units can be combined and matched according to the properties of the oil and water to be separated. Except... Figures 2 to 6 In addition to various combinations of horizontal arrangements, to reduce the lateral footprint, this invention can also adopt triangular or square arrangements, etc., depending on site requirements. When using three basic separation units 1, a compact arrangement can be a horizontal arrangement (e.g., Figure 7-B (as shown) or arranged in a triangular pattern (such as...) Figure 7-C (as shown); when using four basic separation units, the compact layout can be a square layout (as shown). Figure 7-A (As shown).

[0049] Further as Figure 2 As shown, the present invention uses Figure 2The following example illustrates the on-site oil-water separation process of the present invention: The first in-situ oil-water separation device 100 arranged laterally, specifically, uses a four-module system consisting of a gravity sedimentation module, a coalescence separation module, an electrostatic separation module, and a multi-field synergistic separation module to treat oily wastewater.

[0050] First, the liquid to be treated enters the first module tank through the inlet of the gravity settling module and fills the entire tank. The gas contained in the liquid to be treated gathers at the top of the tank and is discharged through the outlet. Under the action of gravity, the liquid in the tank undergoes oil-water separation. The sensor determines whether the upper oil phase has reached the separation standard (based on a preset value). If the standard is reached, the oil outlet of the gravity settling module is opened to discharge the separated oil phase. The lower aqueous phase or incompletely separated emulsion flows from bottom to top through the outlet along the connecting inclined pipe. During the flow, the fluid is heated by a heater to maintain a certain temperature, and further oil-water separation can be carried out by gravity as the fluid rises. The solid impurities contained in the liquid to be treated fall to the bottom of the tank by gravity in the gravity settling module and are discharged through the sand outlet.

[0051] Secondly, the oil-water emulsion flowing from the gravity module enters the second module tank through the inlet of the coalescing separation module. The gas and solid phases that were not completely separated in the first module are discharged from the gas outlet and sand outlet of the second module, respectively. The incompletely separated oil-water emulsion flows from top to bottom in the second module tank. When it flows through the coalescing medium bed, the dispersed oil droplets are coalesced on the surface of the medium due to the wettability of the medium, gradually forming larger oil droplets, thereby increasing the oil-water separation effect. The separated oil phase floats on the upper layer of the tank. The sensor determines whether the separated oil phase can be discharged through the oil outlet. The separated water phase or the incompletely separated emulsion flows into the connecting inclined tube through the water outlet and enters the next module.

[0052] Next, the incompletely separated emulsion flowing out of the coalescence separation module enters the electrostatic separation module (third module) tank through the liquid inlet. The gas and solid phases that were not completely separated in the second module continue to be discharged from the gas outlet and sand outlet of the third module. The liquid to be treated flows from top to bottom in the third module. When it flows through the electrodes, the surface of the dispersed oil droplets is polarized by the electric field. Under the action of dipole moment and electrophoresis, the dispersed oil droplets move violently between the electrodes and collide with each other. After small oil droplets collide, the interfacial film breaks to form large oil droplets, which are separated from the emulsion. The separated oil phase is discharged from the oil outlet, and the water phase that does not meet the standard enters the next module for further separation.

[0053] Finally, the liquid enters the fourth module through the inlet of the multi-field collaborative separation module. If some unseparated gas and solid phases remain after the three-stage separation, they can still be discharged through the gas outlet and sand outlet. The liquid to be treated flows from top to bottom in the fourth module, passing through the electric field and the coalescing medium bed. Under the coupling effect of the coalescing medium and the electric field, the oil phase in the liquid to be treated is further separated. The separated oil phase is discharged from the oil outlet, and the separated water phase is discharged from the water outlet. Sampling is taken to test whether it meets the standards. If it does not meet the standards, more modules can be added, or the existing modules can be modified to increase the oil-water separation capacity.

[0054] Further as Figure 3 As shown, the present invention employs a second on-site oil-water separation device 200 (without a heater connected to the outside of the inclined tube) in another embodiment, which uses a three-module combination of gravity sedimentation modules to treat oily wastewater, and is suitable for oil-water separation with a low degree of emulsification.

[0055] Further as Figure 4 As shown, when the liquid to be treated is oily wastewater and the aqueous phase contains salt, the present invention employs a third on-site oil-water separation device 300 according to another embodiment. The basic separation units are all coalescing media modules and are set in multiple stages. Figure 4 (The example illustrates a three-stage process). For instance, the first stage uses polytetrafluoroethylene (PTFE) coalescing sloping plates, the second stage uses polypropylene microsphere packing, and the third stage uses woven polyethylene fibers. Specifically, when the aqueous phase has a high salt content, electro-demulsification is prone to breakdown, making electro-separation modules unsuitable. However, given the high requirements for oil-water separation, a multi-stage coalescing media separation module is used for deep oil-water separation. Figure 4 The treatment process employs three separation modules, all of which are coalescing separation modules. Because the treated liquid contains a high amount of oil and a high solids content, using high-density stacked packing would cause clogging; therefore, the first module uses polytetrafluoroethylene (PTFE) coalescing inclined plates. The oil-water emulsion after coarse separation has a lower impurity content, but the oil content is still high, requiring further separation; therefore, the second module uses polypropylene microsphere packing. The wastewater after two stages of separation has largely met the standards, but a small amount of microemulsion remains; therefore, the third module uses polyethylene fibers woven according to a specific pattern. The wastewater after three stages of separation can be discharged after passing testing and meeting standards.

[0056] Still with Figure 4 Taking the implementation method in the example, when the fluid to be treated is oilfield produced fluid, the water content of the produced fluid gradually increases with the increase of extraction time. This invention is installed at the oilfield metering station. Figure 4The on-site oil-water separation device 300 shown in the diagram also consists of three-stage coalescing separation modules. In the early stages of oilfield development, the water content is low, and the oil-water emulsion is primarily a water-in-oil emulsion. All three modules are filled with hydrophilic coalescing media. As development progresses and the oilfield enters the middle stage, the initial water content of the produced fluid is about 30%. The first module still uses hydrophilic coalescing media, while the water content increases to about 70% in the second module, and the emulsion changes from primarily water-in-oil to primarily oil-in-water. Because the oilfield focuses more on crude oil water separation efficiency, the second module still uses hydrophilic coalescing media. In the third module, over 90% of the produced fluid is wastewater. To ensure the wastewater meets reinjection standards and further separates crude oil, oleophilic coalescing media is installed in the third module to purify the water and separate the crude oil. In the later stages of oilfield development, the produced fluid is 90% aqueous, and the three modules can be reduced to two, both filled with oleophilic coalescing media. Because the on-site oil-water separator 300 is composed of multiple modules, the operation of replacing modules is simpler, less costly, and more efficient.

[0057] Further as Figure 5 As shown, the present invention adopts a fourth on-site oil-water separation device 400 (without a heater connected to the outside of the inclined tube) in another embodiment, that is, a three-module combination of multiple field synergistic separation modules is used to treat oily wastewater, which is suitable for oil-water separation with a high degree of emulsification and a low salt content in the aqueous phase.

[0058] Further as Figure 6 As shown, this invention employs a fifth in-situ oil-water separation device 500 according to another embodiment. This embodiment differs significantly from the aforementioned embodiments and is suitable for situations where produced oil needs to be separated from oilfield produced fluids in situ. Specifically, when the fluid to be treated is produced oilfield fluid and in-situ separation of produced oil is required, the aforementioned in-situ oil-water separation device of this invention is used inverted, with the original sand outlet set as the gas outlet, the original gas outlet set as the sand outlet, the original water outlet set as the oil outlet, and the original oil outlet set as the water outlet. Separated water is discharged from the water outlet, and the produced oil continues to enter the next stage basic separation unit along the connecting inclined pipe. Figure 6 The implementation method described above can transform the original continuous wastewater treatment into continuous crude oil treatment simply by inverting the original normally used equipment. The method is simple, requires no additional processing or manufacturing, and can minimize operating costs.

[0059] Example 1

[0060] refer to Figure 4Due to years of exploitation, the produced fluid at some wellheads in the Tarim Oilfield of Xinjiang has a water content exceeding 90%. Given the unique geographical location of the Tarim Oilfield and the large distances between wells, including the long distance from the wellhead to the joint station, transporting all the produced fluid to the joint station would consume a significant amount of energy in transporting the produced wastewater, resulting in low efficiency in producing oil transportation. Therefore, this invention is installed at the wellhead or metering station. Figure 4 The combined deep in-situ oil-water separation device shown extracts most of the wastewater from the produced fluid on-site, and after simple treatment to meet the reinjection standards, it is directly reinjected into the formation from the injection well.

[0061] Because the mineralization of produced wastewater from the Tarim Oilfield reaches tens of thousands of milligrams per liter, electro-demulsification is highly susceptible to breakdown. Therefore, the following method is adopted: Figure 4 The three-stage coalescing separation module shown is an in-situ oil-water separation device 300. Due to the high viscosity of crude oil in the Tarim Oilfield, its high content of asphaltene and resin, and the high sand content in the produced fluid, polytetrafluoroethylene (PTFE) coalescing inclined plates, a medium with low flow resistance, are used as the coalescing medium bed in the first-stage coalescing separation module. The produced fluid enters the first module tank through the inlet, flowing through the PTFE coalescing inclined plates, causing dispersed oil droplets in the aqueous phase to aggregate on the plates, thus separating the dispersed oil droplets from the aqueous phase. Produced dry gas and sand particles are discharged from the gas outlet and sand outlet, respectively. After passing through the first module, 80% of the wastewater in the produced fluid is separated from the crude oil. The separated wastewater still contains a certain amount of impurities and oil droplets. The wastewater flowing out of the first module enters the second module. To further reduce the oil phase impurity content in the wastewater, a polypropylene microsphere-filled medium bed is used in the second module. The wastewater flowing out of the second module is basically free of micron-sized oil droplets, but still contains a small amount of nano-sized oil droplets and suspended impurities. To meet the reinjection standards, the wastewater needs further treatment. Polyethylene fibers woven in a specific pattern are installed in the third module. This serves two purposes: firstly, it further coalesces small oil droplets; secondly, it filters out suspended impurities in the wastewater, thus ensuring the wastewater meets reinjection standards. The treated wastewater is discharged from the outlet of the third module, achieving efficient on-site treatment of wellhead produced fluid. This reduces the additional costs associated with long-distance transportation of produced water, improves produced fluid treatment efficiency, and lowers the processing load on the oilfield joint station.

[0062] Example 2

[0063] Due to long-term water injection development, the reservoir rocks on an offshore platform in the Bohai Oilfield have become loosed from erosion. The produced fluid contains a large amount of both water and sand, necessitating on-site water and sand separation treatment. Research has led to the adoption of a four-stage separation module combination of "gravity settling + filtration + two-stage coalescence," with each module having a volume of 60 cubic meters. However, due to space limitations on the offshore platform, arranging the four modules in parallel (i.e., a transverse arrangement) would result in a length exceeding ten meters. Adding external pipelines, valves, and reserved operating and safety space, the total transverse footprint of the unit would reach nearly 100 square meters, which is difficult to achieve on an offshore platform.

[0064] Therefore, by changing the arrangement of the four modules, referencing Figure 7-A The four modules are arranged compactly in a square layout, and an integrated drain pipe and valve are designed and installed in the central gap space to reduce the space occupied by the device. Figure 7-A The layout of the on-site oil-water separator occupies a total horizontal area of ​​approximately 60 square meters, which greatly saves space.

[0065] Example 3

[0066] In a certain block of the Tarim Oilfield, the overall water cut reached 30%. Due to increased production capacity, the combined station's processing load increased, necessitating on-site water separation of the produced oil to alleviate the combined station's load. Therefore, the following method was adopted: Figure 6 The implementation method of "inversion".

[0067] Because the block has low water content, most of the produced water is dispersed in the crude oil in the form of an emulsion. Therefore, continuous processing of the produced oil is required to remove the emulsified water, reduce the viscosity of the crude oil, and improve its quality. Existing combined deep in-situ oil-water separation units are mostly used for continuous treatment of oily wastewater, while purchasing, designing, and manufacturing other in-situ water separation units separately requires a significant amount of time and economic costs.

[0068] Therefore, to meet on-site requirements, the combined deep in-situ oil-water separation device of this invention is still used. No structural changes or additional processing are required; the device is simply inverted, with the original sand outlet becoming the air outlet, the original air outlet becoming the sand outlet, the original water outlet becoming the oil outlet, and the original oil outlet becoming the water outlet. The crude oil to be treated still enters through the inlet, slowly filling the entire tank. The extracted dry gas and sand particles are discharged from the air outlet and sand outlet, respectively. The extracted liquid flows through a hydrophilic medium bed to improve water separation efficiency, and the separated water is discharged from the water outlet. Extracted oil that does not meet the standards continues to flow downwards along the connecting inclined pipe into the next module for further water separation until it meets the export standards. This embodiment transforms the original continuous wastewater treatment into continuous crude oil treatment simply by inverting the device. The method is simple, requires no additional processing or manufacturing, and reduces operating costs.

[0069] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A basic separation unit, characterized in that, Each of the aforementioned basic separation units, through modular assembly, is suitable for oil-water separation in oilfields and / or refineries. This unit is used as a gravity settling module and includes: The tank body has an air outlet at the top and a sand outlet at the bottom; an inlet is located on the upper part of the side wall of the tank body, and a outlet is located on the lower part of the side wall of the tank body; an oil outlet is located above the inlet; a coalescing medium and / or an electrode are also disposed between the inlet and the outlet of the tank body; when the coalescing medium is disposed between the inlet and the outlet of the tank body, the basic separation unit is used as a coalescing separation module; when the electrode is disposed between the inlet and the outlet of the tank body, the basic separation unit is used as an electro-separation module; when the coalescing medium and the electrode are disposed between the inlet and the outlet of the tank body, the basic separation unit is used as a multi-field synergistic... The separation module is used as follows: When the fluid to be treated is oilfield produced fluid, the water content of the produced fluid gradually increases with the increase of the extraction time. Through modular assembly, the number and type of modules are adjusted in the early, middle and late stages of extraction to dynamically treat the fluid to be treated. When the fluid to be treated is oilfield produced fluid and it is necessary to separate the produced oil in situ, the basic separation unit is used in reverse: the original sand outlet is set as the gas outlet, the original gas outlet is set as the sand outlet, the original water outlet is set as the oil outlet, and the original oil outlet is set as the water outlet. The separated water is discharged from the water outlet, and the produced oil continues to enter the next level basic separation unit along the connecting inclined pipe. A sensor is installed at a height between the liquid inlet and the oil outlet inside the tank to sense whether the oil phase to be discharged from the oil and water at the sensor height has reached a preset value. Connect the inclined tube, one end of which is connected to the water outlet, and the other end of which is connected to the liquid inlet of the next basic separation unit.

2. The basic separation unit according to claim 1, characterized in that, The tank body is equipped with an insulation jacket; the connecting inclined tube is equipped with a heater.

3. The basic separation unit according to claim 1, characterized in that, Flow control valves are installed at the liquid inlet, water outlet, and oil outlet.

4. The basic separation unit according to claim 1, characterized in that, The coalescing medium bed can be plate-type, packing-type, or filter-type.

5. The basic separation unit according to claim 1, characterized in that, When the liquid to be treated is an oil-in-water emulsion, the coalescing medium is polytetrafluoroethylene or polypropylene; when the liquid to be treated is a water-in-oil emulsion, the coalescing medium is glass fiber, metal fiber or quartz sand.

6. The basic separation unit according to claim 1, characterized in that, The electrode is either a rod-shaped electrode or an electrode plate.

7. The basic separation unit according to claim 1, characterized in that, When the basic separation unit is used as a multi-field collaborative separation module, the electrodes are inserted in the coalescing medium bed.

8. An on-site oil-water separation device, characterized in that, Includes a basic separation unit as described in any one of claims 1 to 7, wherein there are multiple basic separation units arranged in a compact manner, and the number of basic separation units used and the types of modules are combined and matched according to the properties of the oil and water to be separated.

9. The on-site oil-water separator according to claim 8, characterized in that, When three of the basic separation units are used, the compact arrangement is a horizontal arrangement or a triangular arrangement; when four of the basic separation units are used, the compact arrangement is a square arrangement.

10. The on-site oil-water separation device according to claim 8, characterized in that, When the liquid to be treated is oily wastewater and the aqueous phase contains salt, the basic separation units are all coalescing media modules and are set in multiple stages.

11. The on-site oil-water separator according to claim 10, characterized in that, The multi-stage setup is as follows: the first stage is a polytetrafluoroethylene coalescing slant plate, the second stage is a polypropylene microsphere packing, and the third stage is a woven polyethylene fiber.

12. The on-site oil-water separation device according to claim 8, characterized in that, When the fluid to be treated is produced fluid from the oilfield, the on-site oil-water separation device is installed at the oilfield metering station; in the early stage of oilfield development and when the oil-water emulsion is mainly a water-in-oil emulsion, a three-stage basic separation unit is set up, all of which are coalescing separation modules, and all three stages are filled with hydrophilic coalescing media; in the middle stage of oilfield development, a three-stage basic separation unit is set up, all of which are coalescing separation modules, with the first two stages filled with hydrophilic coalescing media and the third stage filled with oleophilic coalescing media; in the later stage of oilfield development, a two-stage basic separation unit is set up, both of which are coalescing separation modules, and both stages are filled with oleophilic coalescing media.

13. The on-site oil-water separation device according to claim 8, characterized in that, When the fluid to be treated is oilfield produced fluid and on-site water separation of the produced oil is required, the on-site oil-water separation device is used inverted.

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