Basic separation unit and in-situ oil-water separation device using same

Abstract

The invention discloses a basic separation unit and an in-situ oil-water separation device using the same, each basic separation unit is suitable for oil-water separation of an oil field and / or a refinery site through modular assembly, the unit is used as a gravity settling module, and the unit comprises a tank body with a gas outlet at the top and a sand outlet at the bottom; a liquid inlet is formed in the upper part of the side wall of the tank body; an oil outlet is formed above the liquid inlet; the sensor is arranged at the height between the liquid inlet and the oil outlet in the tank body and is used for sensing whether an oil phase to flow out in the oil water at the height of the sensor reaches a preset value or not; one end of the connecting inclined pipe is communicated with the water outlet, and the other end of the connecting inclined pipe is communicated with the liquid inlet of the next basic separation unit. According to the modularized in-situ oil-water separation device, modularized assembly of separation equipment can be carried out according to on-site oil-water properties, large-scale and continuous oil-water separation can be carried out, and the occupied area of the equipment can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of oil-water separation in petroleum and petrochemical industry, and in particular to a basic separation unit used in an oil field or refinery and an on-site oil-water separation device using the unit. Background Art

[0002] Oil-water separation plays a vital role in the fields of petroleum and petrochemicals. Due to the strong mechanical disturbance or a large amount of chemical substances in the process of oil extraction or petrochemical production, crude oil or distillate oil forms a stable emulsion with liquid water. In order to obtain pure products, it is often necessary to demulsify the oil-water emulsion. Generally speaking, oil-water demulsification separation can be roughly divided into two methods: chemical method and physical method. At present, the physical oil-water separation method widely used in industry is gravity sedimentation method, which separates oil and water by gravity by placing the oil-water emulsion in a canned container. This method is simple to operate, but it takes a long time, and when processing a large amount of oil-water emulsion, a large-volume sedimentation tank is often required, which not only has limited processing capacity, but also occupies a large area. For oil-water separation problems that require a large amount of continuous processing and a small available operating area, it is more difficult to use gravity sedimentation separation.

[0003] In industrial practice, there are various physical demulsification methods such as electric demulsification, coalescence medium demulsification, microwave demulsification, ultra-gravity demulsification, and multi-field coupling demulsification. Although these demulsification methods can achieve good oil-water separation effects, they have certain limitations on the properties of the treated oil-water emulsions. Certain pre-treatment processes are often required for different oil-water properties, which limits the widespread use of a specific oil-water separation equipment.

[0004] In addition, for oil fields or refineries, the oil-water emulsion produced by the wellhead or reaction tower often contains a large amount of wastewater or waste oil, and the location of some oil field wellheads or refineries is often far away from the joint station or water treatment plant. Directly transporting the emulsion to the joint station or water treatment plant often causes a lot of waste, and the product transportation efficiency is very low in transporting the wastewater or waste oil in the emulsion. The industry needs to perform rough separation of the oil-water emulsion on-site at the wellhead, transfer station or refinery to remove most of the wastewater or waste oil as much as possible.

[0005] Since the available area at oil fields or refineries is generally small, it is difficult to install large gravity sedimentation equipment, resulting in a small processing capacity. In addition, the properties of oil and water flowing out of different wellheads and reactors are often very different. It is difficult to meet the separation requirements of different conditions by using a unified oil-water separation equipment. 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 equipment that can be used in oil fields or refineries, can effectively, massively and continuously separate different oil-water emulsions and has a small footprint.

[0007] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

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

[0009] To achieve the above-mentioned purpose, according to the first aspect of the present invention, there is provided a basic separation unit, each of which is suitable for oil-water separation in oil fields and / or refineries through modular assembly, and the unit is used as a gravity sedimentation module, comprising: a tank body, with an air outlet on the top and a sand outlet on the bottom; a liquid inlet on the upper part of the side wall of the tank body and a water outlet on the lower part of the side wall of the tank body; an oil outlet above the liquid inlet; a sensor, which is arranged at a height between the liquid inlet and the oil outlet in the tank body, and is used to sense whether the oil phase to be discharged in the oil and water at the height of the sensor reaches a preset value; a connecting inclined pipe, one end of which is connected to the water outlet, and the other end is connected to the liquid inlet of the next basic separation unit.

[0010] Furthermore, in the above technical solution, a heat-insulating interlayer may be provided inside the tank body; and a heater may be provided outside the connecting inclined pipe.

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

[0012] Furthermore, in the above technical solution, a coalescing medium and / or an electrode may be arranged between the liquid inlet and the water outlet in the tank body.

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

[0014] Furthermore, in the above technical solution, the bed of the coalescing medium may be of plate type, filler 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 an oil-in-water emulsion, the coalescing medium can be glass fiber, metal fiber or quartz sand, etc.

[0016] Furthermore, in the above technical solution, the electrodes may be rod-shaped electrodes or electrode plates.

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

[0018] According to the second aspect of the present invention, the present invention provides an on-site oil-water separation device, comprising any one of the basic separation units described above, the number of basic separation units can be multiple and arranged in a compact manner, and the number of basic separation units used and the type 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 arrangement can be designed as a horizontal arrangement or a herringbone arrangement; when four basic separation units are used, the compact arrangement can be designed as a square arrangement.

[0020] Furthermore, in the above technical solution, when the liquid to be treated is oily wastewater and the water phase contains salt, the basic separation units can all be coalescing medium modules and can be arranged in multiple stages. The multiple stages can be specifically: the first stage is provided with a polytetrafluoroethylene coalescing inclined plate, the second stage is provided with a polypropylene ball filler, and the third stage is provided with a woven polyethylene fiber.

[0021] Furthermore, in the above technical scheme, when the liquid to be treated is oilfield produced liquid, the on-site oil-water separation device is set at the oilfield transfer station; in the early stage of oilfield exploitation and when the oil-water emulsion is mainly oil-in-water emulsion, three-level basic separation units can be set and all of them are coalescence separation modules, and all three levels are filled with hydrophilic coalescence medium; in the middle stage of oilfield exploitation, three-level basic separation units are set and all of them are coalescence separation modules, among which the first two stages can be filled with hydrophilic coalescence medium, and the third stage can be filled with oleophilic coalescence medium; in the late stage of oilfield exploitation, two-level basic separation units can be set and all of them are coalescence separation modules, and both stages are filled with oleophilic coalescence medium.

[0022] Furthermore, in the above technical scheme, when the liquid to be treated is oilfield produced liquid and the produced oil needs to be separated on-site, the on-site oil-water separation device is used inverted, the original sand outlet is set as the air outlet, the original air 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.

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

[0024] 1) The present invention uses the basic separation unit as the smallest unit, sets internal components in the basic separation unit, and constructs separation modules of different physical separation types. The modular assembly of separation equipment can be carried out according to the oil and water properties at the oil field or refinery site. It can not only achieve multi-stage separation, achieve better oil-water separation effect, and perform large-scale and continuous oil-water separation, but also effectively reduce the floor space of the equipment;

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

[0026] 3) The present invention connects the modules in series by connecting oblique pipes, which makes installation and disassembly easier, and can be dynamically adjusted according to the conditions of the on-site treated fluid, with short downtime and simple operation;

[0027] 4) When the liquid to be treated is oilfield produced liquid, the water content of the produced liquid gradually increases with the increase of production time. Therefore, the modular device of the present invention can adjust the number and type of modules in the early, middle and late stages of production, so it has stronger adaptability and can dynamically treat the liquid to be treated, which can effectively increase the processing volume and processing capacity and reduce the subsequent oil and water treatment load;

[0028] 5) When the produced fluid of the oil field needs to be separated from the produced oil on site, the present invention can use the on-site oil-water separation device invertedly. By swapping the openings of each tank body, 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. Only by inverting the original normally used device, the original continuous treatment of sewage can be converted into continuous treatment of crude oil. The method is simple, does not require additional processing and manufacturing, and can minimize operating costs.

[0029] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, and to make the above and other purposes, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 is a schematic diagram of the structure of the basic separation unit of the present invention (wherein Figure 1-A Used as a gravity sedimentation module; Figure 1-B Used as a coalescence separation module; Figure 1-C Used as an electrical separation module; Figure 1-D Used as a multi-field cooperative separation module).

[0031] Figure 2It is a structural schematic diagram of the first combined implementation mode of the on-site oil-water separation device of the present invention (the four-stage separation uses a gravity sedimentation module, a coalescence separation module, an electrical separation module and a multi-field collaborative separation module respectively).

[0032] Figure 3 It is a structural schematic diagram of the second combination implementation mode of the on-site oil-water separation device of the present invention (all three stages use gravity sedimentation modules and the connecting inclined pipes do not use heaters).

[0033] Figure 4 It is a structural schematic diagram of the third combination implementation mode of the on-site oil-water separation device of the present invention (all three stages use a coalescence separation module).

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

[0035] Figure 6 It is a structural schematic diagram of the fifth combined implementation mode of the on-site oil-water separation device of the present invention (the basic separation units of the present invention are inverted and used in combination, which is suitable for the case where the liquid to be treated is oilfield produced liquid and the produced oil needs to be separated from water on-site).

[0036] FIG. 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 (where Figure 7-A Showing a square arrangement; Figure 7-B Showing the horizontal arrangement; Figure 7-C )

[0037] Description of main reference numerals:

[0038] 1-basic separation unit, 1A-gravity sedimentation module, 1B-coalescence separation module, 1C-electrical separation module, 1D-multi-field collaborative separation module, 10-tank body, 11-gas outlet, 12-sand outlet, 13-liquid inlet, 14-oil outlet, 15-water outlet, 16-coalescence medium bed, 17-electrode, 2-sensor, 3-connecting inclined pipe, 31-heater.

[0039] 100 - the first on-site oil-water separation device, 200 - the second on-site oil-water separation device, 300 - the third on-site oil-water separation device, 400 - the fourth on-site oil-water separation device, 500 - the fifth on-site oil-water separation device. DETAILED DESCRIPTION

[0040] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0041] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0042] In this document, for the convenience of description, spatial relative terms such as "below", "below", "down", "above", "above", "upper", etc. may be used to describe the relationship between one element or feature and another element or feature in the accompanying drawings. It should be understood that the spatial relative terms are intended to include different orientations of the object in use or operation in addition to the orientation depicted in the figure. For example, if the object in the figure is turned over, the element described as being "below" or "below" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both below and above. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used in this document 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 limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable.

[0044] As shown in FIG1 , the present invention provides a basic separation unit 1 for oil-water separation at an oil field and / or refinery site (i.e., on-site oil-water separation). Each basic separation unit 1 can be assembled in a modular manner according to site needs and the properties of oil and water to perform oil-water separation. The most basic basic separation unit can be used as a gravity sedimentation module 1A (see FIG1A ). Figure 1-A), including a tank body 10, a sensor 2 and a connecting inclined tube 3. Among them, the tank body 10 is provided with an air outlet 11 at the top and a sand outlet 12 at the bottom; the tank body 10 is provided with a liquid inlet 13 at the upper part of the side wall, and a water outlet 15 at the lower part of the side wall; and an oil outlet 14 is provided above the liquid inlet 13. The sensor 2 is arranged at a height between the liquid inlet 13 and the oil outlet 14 in the tank body 10, and is used to sense whether the oil phase to be discharged in the oil and water at the height of the sensor reaches a preset value. The sensor 2 is arranged between the liquid inlet and the oil outlet, and the oil phase flowing out of the oil outlet can reach the expected index by sensing the oil-water content at the sensor, so as to prevent the 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 body 10 can be a cylindrical metal tank body, which is the main shell of the basic separation unit 1. The tank body 10 is provided with a thermal insulation interlayer inside for temperature control of the tank body. The separated gas phase can flow out from the gas outlet 11; the separated solid phase particles can be discharged from the sand outlet 12; the oil outlet 14, the liquid inlet 13 and the water outlet 15 are arranged in sequence from top to bottom along both sides of the tank body 10, and the separated oil phase can be discharged from the oil outlet 14 after gravity sedimentation, and 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 can be discharged from the water outlet 15 after gravity sedimentation. Flow control valves are provided outside all openings on the tank body 10. Furthermore, a heater 31 can be provided outside the connecting inclined pipe 3, and the heater can adopt various heating forms such as electric heating, downstream / countercurrent heat exchange, combustion heating, radiation heating, etc. The specific heater type can be determined according to the conditions of the construction site.

[0045] like Figure 1-A The figure shows a basic module of the basic separation unit. The present invention uses the module as a gravity sedimentation module 1A. The present invention changes the module function by adding or removing the internal components of the module. In addition to the gravity sedimentation module 1A, it also includes a coalescence separation module 1B (refer to Figure 1-B )、Electrical separation module 1C (reference Figure 1-C ) and multi-field cooperative separation module 1D (reference Figure 1-D ) etc. By combining various modules, the purpose of efficient separation of oil-water emulsions with different properties can be achieved, and on-site oil-water separation at the oil field or refinery site can be realized to overcome the shortcomings of existing on-site oil-water separation equipment, such as small processing capacity, long processing time and poor processing effect.

[0046] Further Figure 1-B to Figure 1-D As shown, in order to construct more basic separation units, the present invention, based on the gravity sedimentation module 1A, sets a coalescing medium and / or an electrode between the liquid inlet and the water outlet in the tank body, thereby obtaining Figure 1-B The coalescence separation module 1B shown in the figure (which can realize the coupled demulsification separation of gravity field + coalescence field) is a coalescence medium bed 16 arranged between the liquid inlet 13 and the water outlet 15, and can also obtain Figure 1-C The electrical separation module 1C shown in the figure (which can realize the coupled demulsification separation of gravity field + electric field) is provided with an electrode 17 between the liquid inlet 13 and the water outlet 15, and can also obtain Figure 1-D The multi-field collaborative separation module 1D shown (that is, coupled demulsification separation of gravity field + coalescence field + electric field), that is, when the basic separation unit 1 is used as a multi-field collaborative separation module 1D, the electrode 17 is inserted in the coalescence medium bed 16. In summary, when the coalescence medium bed 16 is set between the liquid inlet 13 and the water outlet 15, the basic separation unit is used as a coalescence separation module 1B; when the electrode 17 is set between the liquid inlet 13 and the water outlet 15, the basic separation unit is used as an electric separation module 1C; when the coalescence medium and the electrode are set between the liquid inlet 13 and the water outlet 15, the basic separation unit is used as a multi-field collaborative separation module 1D. The present invention is not limited to this. In addition to constructing the aforementioned modules, magnetic plates can be added to the tank body 10 as needed to achieve electromagnetic demulsification; a stirring device can also be added to achieve ultra-gravity oil-water separation, etc., which will not be described in detail here.

[0047] Further, preferably but not restrictively, the coalescing medium bed can be a plate type, a packing type or a filter element type. In addition, different types of coalescing media can be selected according to 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 made of polytetrafluoroethylene or polypropylene, etc.; when the liquid to be treated is an oil-in-water emulsion, the coalescing medium can be made of glass fiber, metal fiber or quartz sand, etc. The electrodes in the above-mentioned electrical separation module 1C can be rod electrodes or electrode plates, etc.

[0048] The present invention also provides an on-site oil-water separation device using the aforementioned basic separation unit, in which the basic separation units are multiple and compactly arranged, and the number of basic separation units used and the types of modules can be combined and matched according to the properties of the oil and water to be separated. Figures 2 to 6 In addition to various combinations of lateral arrangements, in order to reduce the lateral space occupied, the present invention can also adopt a herringbone arrangement and a square arrangement and the like according to the needs of the site. When three basic separation units 1 are used, the compact arrangement can be a lateral arrangement (such as Figure 7-B as shown) or in a herringbone arrangement (as shown Figure 7-C When four basic separation units are used, the compact arrangement can be a square arrangement (as shown in FIG. Figure 7-A shown).

[0049] Further Figure 2 As shown, the present invention is Figure 2The combination mode in the embodiment (the first on-site oil-water separation device 100 arranged horizontally), that is, the four-module composition of "gravity sedimentation module + coalescence separation module + electrical separation module + multi-field collaborative separation module" is used as an example to illustrate the on-site oil-water separation process of the present invention:

[0050] First, the liquid to be treated enters the tank of the first module through the liquid inlet of the gravity sedimentation 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 gas outlet; the liquid in the tank is separated from oil and water under the action of gravity, and the sensor is used to determine whether the upper oil phase meets the separation standard (based on the preset value). If the standard is met, the oil outlet of the gravity sedimentation module is opened to discharge the separated oil phase; the lower water phase or the incompletely separated emulsion flows from bottom to top along the connecting inclined pipe through the water outlet, and is heated by the heater during the flow process to keep the fluid at a certain temperature, and the oil and water can be further separated by gravity during the rising process of the fluid; the solid impurities contained in the liquid to be treated fall to the bottom of the tank by gravity in the gravity sedimentation module and are discharged through the sand outlet;

[0051] Secondly, the oil-water emulsion flowing out of the gravity module enters the second module tank through the liquid inlet of the coalescence separation module, and the gas phase and solid phase that are 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, and when flowing through the coalescence medium bed, it is affected by the wettability of the bed medium surface, causing the dispersed oil droplets to coalesce on the medium surface, gradually forming larger oil droplets, thereby increasing the oil-water separation effect; the separated oil phase floats on the upper layer of the tank, and 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 pipe through the water outlet and enters the next module;

[0052] Again, the unseparated complete emulsion flowing out of the coalescence separation module enters the tank of the electrical separation module (the third module) through the liquid inlet, and the gas phase and solid phase that are 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, and when flowing 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 and collide with each other between the electrodes. After the collision of small oil droplets, the interfacial film ruptures to form large oil droplets, which are separated from the emulsion; the separated oil phase is discharged from the oil outlet, and the unqualified water phase further enters the next module for further separation.

[0053] Finally, the liquid enters the fourth module through the liquid inlet of the multi-field collaborative separation module. If there are still some unseparated gas and solid phases after the three-stage separation, they can still be discharged through the gas outlet and the sand outlet; the liquid to be treated flows from top to bottom in the fourth module, flows through the electric field and the coalescing medium bed, and under the coupling action 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, and sampling is carried out to detect whether it meets the standards. If not, further modules can be added, or the existing modules can be modified to increase the oil-water separation capacity.

[0054] Further Figure 3 As shown, the present invention adopts another embodiment of the second on-site oil-water separation device 200 (no heater is used outside the connecting inclined tube), that is, a three-module combination of gravity sedimentation modules is used to treat oily wastewater, which is suitable for oil-water separation with a low emulsification degree.

[0055] Further Figure 4 As shown, when the liquid to be treated is oily wastewater and the water phase contains salt, the present invention adopts another embodiment of the third on-site oil-water separation device 300. The basic separation units are all coalescing media modules and are arranged in multiple stages ( Figure 4 For example, a polytetrafluoroethylene coalescing inclined plate is provided in the first stage, a polypropylene ball filler is provided in the second stage, and a woven polyethylene fiber is provided in the third stage. Specifically, when the salt content of the aqueous phase is high, the use of electric demulsification is very likely to cause breakdown, so it is not suitable to use an electric separation module, and there are higher requirements for oil-water separation, so a multi-stage coalescing medium separation module is used for deep oil-water separation. Figure 4 Three separation modules are used, all of which are coalescence separation modules. Since the treated liquid contains more oil and a higher solid content, the use of high-density stacking fillers will cause blockage, so the first module uses polytetrafluoroethylene coalescence inclined plates; the oil-water emulsion after rough separation has less impurities, but the oil content is still high, and further separation is required, so the second module uses polypropylene ball fillers; the sewage after two-stage separation has basically met the standards, but there is still a small amount of microemulsion, so the third module uses polyethylene fibers woven according to a certain pattern. The sewage after three-stage separation can be discharged after being tested and meeting the standards.

[0056] Still Figure 4 For example, when the liquid to be treated is oilfield produced liquid, the water content of the produced liquid gradually increases with the increase of production time. Figure 4The on-site oil-water separation device 300 shown in the figure is also composed of three-stage coalescence separation modules. In the early stage of oilfield exploitation, the water content is small, and the oil-water emulsion is mainly oil-in-water emulsion. The three modules are filled with hydrophilic coalescence medium; as the exploitation progresses, the oilfield exploitation enters the middle stage, and the initial water content of the produced fluid is about 30%. The hydrophilic coalescence medium is still installed in the first module. The water content in the second module increases to about 70%, and the emulsion changes from being mainly oil-in-water type to being mainly water-in-oil type. Since the oilfield site pays more attention to the efficiency of crude oil water separation, the hydrophilic coalescence medium is still installed in the second module. More than 90% of the emulsion entering the third module is produced wastewater. In order to make the produced wastewater meet the reinjection standard and further separate the crude oil at the same time, the oleophilic coalescence medium is installed in the third module to achieve the purpose of purifying water quality and separating crude oil; when the oilfield exploitation enters the late stage, 90% of the produced fluid is water phase, and the three modules can be reduced to two modules, and all are filled with oleophilic coalescence medium. Since the on-site oil-water separation device 300 is composed of a plurality of modules, the operation of replacing the modules is simpler, the cost is lower, and the efficiency is higher.

[0057] Further Figure 5 As shown, the present invention adopts another embodiment of the fourth on-site oil-water separation device 400 (no heater is used on the outside of the connected inclined tube), that is, a three-module combination of multi-field collaborative 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 water phase.

[0058] Further Figure 6 As shown, the present invention adopts another embodiment of the fifth on-site oil-water separation device 500. This embodiment is significantly different from the aforementioned embodiment and is suitable for situations where oilfield produced fluid needs to separate water from produced oil on-site. Specifically, when the liquid to be treated is oilfield produced fluid and the produced oil needs to be separated water on-site, the aforementioned on-site oil-water separation device of the present invention is used inverted, the original sand outlet is set as the air outlet, the original air outlet is set as the sand outlet, the original water outlet is set as the oil outlet, 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. Figure 6 In the implementation method, the original continuous sewage treatment can be converted into continuous crude oil treatment by simply inverting the original normally used device. The method is simple, no additional processing and manufacturing are required, and the operating cost can be reduced to the maximum extent.

[0059] Example 1

[0060] refer to Figure 4Due to years of exploitation in Xinjiang Tahe Oilfield, the water content of some wellhead produced fluids is more than 90%. Due to the special geographical location of Tahe Oilfield, the distance between wells is large, and the distance from the wellhead to the joint station is long. If all the produced fluids are transported to the joint station, a lot of energy will be consumed in transporting produced wastewater, and the transport efficiency of produced oil is low. Therefore, the invention is installed at the wellhead or the meter transfer station. Figure 4 The combined deep in-situ oil-water separation device shown in the figure extracts most of the wastewater from the produced fluid in-situ, and after simple treatment to meet the reinjection standard, it is directly reinjected into the formation from the injection well.

[0061] Since the mineralization of the produced wastewater in the Tahe Oilfield reaches hundreds of thousands of milligrams per liter, it is very easy to break down when using electric demulsification separation. Figure 4 The in-situ oil-water separation device 300 of the three-stage coalescence separation module is shown. Since the crude oil in the Tahe Oilfield has a high viscosity, a high content of colloid asphaltene, and a high sand content in the produced fluid, a medium with low flow resistance, such as a polytetrafluoroethylene coalescence inclined plate, is used as the coalescence medium bed in the first-stage coalescence separation module. The produced fluid enters the first module tank through the liquid inlet, flows through the polytetrafluoroethylene coalescence inclined plate, and causes the dispersed oil droplets in the water phase to gather on the inclined plate, thereby separating the dispersed oil droplets from the water phase; the produced dry gas and sand particles are discharged from the gas outlet and the sand outlet, respectively. After passing through the first module, 80% of the sewage in the produced fluid is separated from the crude oil, and the separated sewage still contains a certain amount of impurities and oil droplets. The sewage flowing out of the first module enters the second module. In order to further reduce the impurity content of the oil phase in the sewage, polypropylene balls are used to fill the medium bed in the second module. The sewage flowing out of the second module basically does not contain micron-level oil droplets, but still contains a small amount of nano-level oil droplets and suspended impurities. In order to make the sewage meet the reinjection standard, the sewage needs to be further treated. The third module is equipped with polyethylene fibers woven in a certain pattern, which can further aggregate small oil droplets on the one hand, and filter out suspended impurities in the sewage on the other hand, so that the sewage meets the re-injection standard. The treated sewage is discharged from the outlet of the third module, realizing efficient on-site treatment of the wellhead produced fluid, reducing the additional cost of long-distance transportation of produced water, improving the efficiency of produced fluid treatment, and reducing the processing load of the oilfield joint station.

[0062] Example 2

[0063] Due to long-term water injection development, the sand particles in the reservoir rock of an offshore platform in Bohai Oilfield have been washed loose, and the produced fluid contains a lot of water and sand. The produced fluid needs to be separated and sanded on the platform. After research, a four-stage separation module combination of "gravity sedimentation + filtration + two-stage coalescence" is adopted, and the volume of each module is 60 cubic meters. However, due to the space limitation of the offshore platform, if the four modules are arranged in parallel (i.e., horizontal arrangement), the length can reach more than ten meters, plus the external pipeline valve and reserved operation and safety space, the total horizontal area of ​​the device will reach nearly 100 square meters, which is difficult to achieve on the offshore platform.

[0064] Therefore, by changing the arrangement of the four modules, refer to Figure 7-A , four modules are compactly arranged to form a square layout, and the central void space is used to design and install integrated oil drain pipes and valves to reduce the space occupied by the device. Figure 7-A The on-site oil-water separation device is arranged in a way that the total horizontal area is about 60 square meters, which greatly saves the device space.

[0065] Example 3

[0066] The comprehensive water content of a block in Tahe Oilfield reaches 30%. Due to the increase in production capacity, the processing load of the joint station has increased. It is necessary to separate the produced oil locally to share the load of the joint station. Therefore, Figure 6 The "inverted" implementation method.

[0067] Since the water content of this block is low, most of the produced water is dispersed in the crude oil in the form of emulsion, so the produced oil needs to be continuously treated to remove the emulsified water, reduce the viscosity of the crude oil, and improve the quality of the crude oil. The existing combined deep on-site oil-water separation device is mostly used for continuous treatment of oily wastewater, while the separate purchase, design, and manufacture of other on-site water separation devices requires a lot of time and economic costs.

[0068] Therefore, in order to meet the needs on site, the combined deep on-site oil-water separation device of the present invention is still used, without changing the structure or additional processing. The device is only placed upside down, and the original sand outlet becomes the gas outlet, the original gas outlet becomes the sand outlet, the original water outlet becomes the oil outlet, and the original oil outlet becomes the water outlet. The crude oil to be processed still enters from the liquid inlet and slowly fills the entire tank body. The produced dry gas and sand particles are discharged from the gas outlet and the sand outlet respectively. The produced liquid flows through the hydrophilic medium bed to improve the water separation efficiency. The separated water is discharged from the water outlet. The produced oil that does not meet the standard continues to tilt downward along the connecting inclined pipe to enter the next module to continue water separation until it reaches the external transmission standard. This embodiment converts the original continuous sewage treatment into continuous crude oil treatment only by inverting the device. The method is simple, no additional processing and manufacturing are required, and the operating cost is reduced.

[0069] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. Any simple modifications, equivalent changes and modifications made to the above 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 basic separation units is modularly assembled and suitable for oil-water separation at oil fields and / or refineries. The unit is used as a gravity sedimentation module and includes: The tank body has an air outlet on the top and a sand outlet on the bottom; a liquid inlet is provided on the upper part of the side wall of the tank body, and a water outlet is provided on the lower part of the side wall of the tank body; an oil outlet is provided 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 to sense whether the oil phase to be discharged in the oil-water at the height of the sensor reaches a preset value; A connecting inclined tube has one end connected to the water outlet and the other end connected to the liquid inlet of the next basic separation unit.

2. The basic separation unit according to claim 1, characterized in that: A heat-insulating interlayer is arranged inside the tank body; a heater is arranged outside the connecting inclined pipe.

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

4. The basic separation unit according to any one of claims 1 to 3, characterized in that: A coalescing medium and / or an electrode is arranged between the liquid inlet and the water outlet in the tank body.

5. The basic separation unit according to claim 4, characterized in that: When the coalescing medium is arranged between the liquid inlet and the water outlet, the basic separation unit is used as a coalescing separation module; when the electrode is arranged between the liquid inlet and the water outlet, the basic separation unit is used as an electrical separation module; when the coalescing medium and the electrode are arranged between the liquid inlet and the water outlet, the basic separation unit is used as a multi-field collaborative separation module.

6. The basic separation unit according to claim 5, characterized in that: The bed layer of the coalescing medium is of plate type, filler type or filter element type.

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

8. The basic separation unit according to claim 5, characterized in that: The electrodes are rod-shaped electrodes or electrode plates.

9. The basic separation unit according to claim 5, characterized in that: When the basic separation unit is used as a multi-field cooperative separation module, the electrodes are inserted in the coalescing medium bed.

10. An on-site oil-water separation device, characterized in that: It comprises a basic separation unit as described in any one of claims 1 to 9, wherein the basic separation units are in multiple number and 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.

11. The on-site oil-water separation device according to claim 10, characterized in that: When three of the basic separation units are used, the compact arrangement is a horizontal arrangement or a herringbone arrangement; when four of the basic separation units are used, the compact arrangement is a square arrangement.

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

13. The on-site oil-water separation device according to claim 12, characterized in that: The multi-stage arrangement is specifically as follows: a polytetrafluoroethylene agglomeration inclined plate is arranged at the first stage, a polypropylene ball filler is arranged at the second stage, and a woven polyethylene fiber is arranged at the third stage.

14. The on-site oil-water separation device according to claim 10, characterized in that: When the liquid to be treated is oilfield produced liquid, the on-site oil-water separation device is arranged at the oilfield metering station; in the early stage of oilfield exploitation and when the oil-water emulsion is mainly water-in-oil emulsion, three-stage basic separation units are arranged and all of them are coalescence separation modules, and all three stages are filled with hydrophilic coalescence medium; in the middle stage of oilfield exploitation, three-stage basic separation units are arranged and all of them are coalescence separation modules, wherein the first two stages are filled with hydrophilic coalescence medium, and the third stage is filled with oleophilic coalescence medium; in the late stage of oilfield exploitation, two-stage basic separation units are arranged and all of them are coalescence separation modules, and both stages are filled with oleophilic coalescence medium.

15. The on-site oil-water separation device according to claim 10, characterized in that: When the liquid to be treated is oilfield produced liquid and the produced oil needs to be separated on-site, the on-site oil-water separation device is used inverted, the original sand outlet is set as the air outlet, the original air outlet is set as the sand outlet, the original water outlet is set as the oil outlet, 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.

Images