Oil field produced water pre-separation method and device capable of reducing occupied area

Abstract

The invention discloses an oilfield produced water pre-separation method and device capable of reducing the occupied area, in the produced water pre-separation device, independent and mutually communicated treatment spaces are isolated in a tank body by a separation module, produced water passes through the arranged treatment spaces one by one, and the particle sizes of obtained oil drops are gradually increased; an oil phase layer and a water phase layer are formed in the corresponding treatment space and are finally output respectively; the produced water pre-separation devices can be connected and combined according to needs, and the separation modules in the produced water pre-separation devices can be independently installed or installed in the tank body in a combined mode according to needs. The oil field produced water is subjected to a step-by-step and graded modular oil removal method, coalescence of oil drops with different particle sizes before and after treatment in different treatment spaces is realized step by step in sequence, the coalescence efficiency of the oil drops is improved on the whole, and the oil field produced water pre-separation treatment device is a device for removing oil from the oil field produced water under the same produced water pre-separation treatment effect. And a device which is more compact and can reduce the occupied area of equipment can be adopted.

Description

Technical Field

[0001] The invention belongs to the field of oil-water separation equipment used in the petroleum industry, and in particular relates to an oilfield produced water pre-separation method and device capable of reducing floor space. Background Art

[0002] Common treatment devices for removing oil from produced water of heavy oil fields are inclined plate deoilers and aerated flotation devices. The disadvantage of both devices is that the separation effect is positively correlated with the floor area, and the floor area is the main determining factor for the separation effect. Therefore, improving the separation effect of such devices will lead to an increase in their floor area, and for offshore oil platforms that need to control the floor area, the separation effect is difficult to improve. The separation equipment and separation effect that can be used for produced water from oil fields with limited floor area such as offshore platforms are a problem to be solved.

[0003] The traditional treatment process for produced water from offshore oilfield platforms is: oil well produced fluid - three-phase separator - inclined plate deoiler - aerated flotation device - walnut shell filter - standard treatment.

[0004] In the above-mentioned produced water treatment device, the inclined plate deoiler and aerated flotation device are large in size and occupy a large area. However, the space on the offshore platform is small, and the equipment in the above-mentioned treatment process occupies a large area, and the space on the built platform is usually not suitable for production expansion.

[0005] In addition, in order to ensure that the oil content of produced water meets the standards, a certain amount of demulsifiers, flocculants and other chemical agents need to be added to the aerated flotation device, which will have a certain impact on the marine ecological environment.

[0006] Therefore, offshore oil platforms require a method and device for pre-separating oilfield produced water that is small in size, low in maintenance cost, and high in separation efficiency.

[0007] After searching, there are several patent technologies for produced water treatment devices like this: Authorization announcement number CN215365332U discloses an offshore platform produced water treatment device, which is equipped with a sedimentation tank, a degradation tank and a membrane biological reaction tank. The device can filter, degrade and purify offshore produced water, and can regenerate the oil contained in the produced water.

[0008] However, the above-mentioned device occupies a large area and takes a long time to process, and is not suitable for produced water treatment with a larger production scale.

[0009] Authorization announcement number CN213085649U discloses a combined rapid oil-water separation device, in which a cyclone assembly, a coalescer assembly and an inclined plate assembly are sequentially installed to form a primary separation cabin, a secondary separation cabin and a tertiary separation cabin respectively to perform three stages of oil-water separation. The device has a large separation capacity and high efficiency for produced water treatment.

[0010] However, due to the built-in inclined plate assembly, the length of the device will be relatively long while ensuring efficiency, and the liquid level is controlled within the tank body, resulting in a larger tank diameter; in addition, the three separation cabins are not completely isolated, independent, and connected.

[0011] The above-mentioned combined device is not suitable for water treatment of heavy oil with a high oil-water ratio. The light phase separated by the cyclone assembly arranged therein is directly discharged into the oil-water separation chamber, and then overflows from the weir plate to the right space for discharge. In this process, the light phase discharged from the cyclone assembly contains a water phase with oil droplets, so the oil-water separation effect is not good.

[0012] CN110078236A discloses a water treatment system and a treatment method suitable for offshore oil field platforms. The system includes a production separator, a pre-filter, a deep coalescing oil remover and a fiber ball filter. The system has a small space requirement while ensuring that produced water meets discharge standards.

[0013] However, since the above system relies on coalescence to remove oil, it cannot handle oil with a viscosity above 1000 mPa·s and a density above 900kg / m 3 The above heavy oils are limited in their scope of application. Summary of the invention

[0014] In order to reduce the floor space occupied by oilfield produced water separation equipment, the present application provides a method and device for pre-separation of oilfield produced water that can reduce the floor space occupied, so that its separation efficiency and maintenance cost can meet the use requirements of working places such as offshore platforms, and provide a separation method and separation equipment for oilfield produced water with limited floor space in working places such as offshore platforms.

[0015] The technical solution of the present invention is: a method for pre-separating produced water from an oil field which can reduce the floor space occupied: in a produced water pre-separation device, a separation module isolates independent and interconnected processing spaces in a tank body, allowing produced water to pass through the set processing spaces one by one and the obtained oil droplet particle size increases step by step, and an oil phase layer and a water phase layer are formed in the corresponding processing space and finally output separately; the produced water pre-separation devices can be connected and combined as needed, and the separation modules in the produced water pre-separation devices can also be installed independently or in combination in the tank body as needed.

[0016] A produced water pre-separation device for an oilfield produced water pre-separation method capable of reducing floor space, comprises a tank body, wherein a water inlet and a water outlet are arranged in the tank body, wherein: the tank body is mainly divided into independent and mutually connected cyclone processing space, processing space 2, processing space 3 and processing space 4 by enhanced separation module 1, coalescence separation module and enhanced separation module 2; a cyclone separation module connected to the water inlet is arranged in the cyclone processing space, and light phase discharge structure 1 and light phase discharge structure 2 are respectively arranged in processing space 2 and processing space 4; the cyclone separation module is provided with a liquid inlet pipe and a cyclone mechanism in which a cyclone is arranged, and the inlet is provided with a cyclone mechanism, wherein a cyclone is arranged in the cyclone processing space; The liquid pipe is connected with the water inlet, and the cyclone mechanism is installed in the liquid inlet pipe; the produced water from the oil field enters from the water inlet, and successively enters the cyclone processing space equipped with the cyclone separation module, the processing space 2 equipped with the light phase discharge structure 1, the processing space 3 and the processing space 4 equipped with the light phase discharge structure 2; the oil phase layer formed in the processing space 2 and the processing space 4 is output by the light phase discharge structure 1 and the light phase discharge structure 2, and the separated water is finally output from the drain port; the produced water pre-separation devices can be installed independently or in combination; the separation modules in the produced water pre-separation device can also be installed independently or in combination in the tank body as needed.

[0017] Preferably, the cyclone mechanism connected to the liquid inlet pipe is arranged at one or more and is connected in series or in parallel with the water inlet through the liquid inlet pipe; the cyclone mechanism is also provided with a steady flow pipe, a water collecting pipe and a cyclone pipe, the water collecting pipe is provided with a dehydration inner pipe, the steady flow pipe can be inserted into the dehydration inner pipe, and the cyclone is fixed at the lower part of the tube body of the cyclone pipe; the steady flow pipe, the water collecting pipe and the cyclone pipe are connected from top to bottom by flanges.

[0018] Preferably, flanges are provided at both ends of the tube body of the water collecting tube, the dehydration inner tube is a tapered tube that is small at the top and large at the bottom and is arranged in an outer sleeve, the pipe openings at both ends of the tube body of the dehydration inner tube are respectively connected to the central holes of the flanges at both ends of the water collecting tube and a dehydration cavity is formed between the flanges at both ends of the tube body and the outer sleeve; a water outlet is provided in the tube body of the dehydration inner tube and the upper end of the tube body is an oil phase outlet, and a water phase outlet is provided in the outer sleeve; the flow stabilizing tube can be inserted into the dehydration inner tube from the oil phase outlet.

[0019] Preferably, the water outlet holes are arranged longitudinally in the tube body of the dehydration inner tube and there are more than six water outlet holes in each row; the aperture of the water outlet holes is smaller than the aperture of the water phase outlet, and the inclination angle β between the dehydration inner tube and the flange end face is 80-85°; the water phase outlet in the outer sleeve is arranged at more than two.

[0020] Preferably, a flange is provided on the upper part of the pipe body of the flow stabilizing pipe, and the pipe body is divided into an outlet section and a flow stabilizing section by the flange; the length of the flow stabilizing section in the flow stabilizing pipe is greater than the length of the dehydration inner pipe in the water collecting pipe.

[0021] Preferably, the cyclone is interference fit with the inner circle of the tube body of the cyclone tube, the upper and lower parts of the cyclone are respectively a baffle section and a guide section, the outer wall of the body between the baffle section and the guide section is a spiral blade, the outer diameter of the baffle section is smaller than the outer diameters of the spiral blade and the guide section; the outer wall of the body of the guide section is provided with a longitudinal straight groove connected to the spiral groove in the spiral blade; the angle α between the longitudinal straight groove and the spiral groove in the spiral blade is set between 30 degrees and 60 degrees.

[0022] Preferably, the coalescence and separation module is a multi-gap oil-coagulating structure formed by weaving oleophilic and hydrophobic fibers or hydrophilic and oleophobic fibers singly or mixedly.

[0023] Preferably, aeration tube one is fixed on the liquid inlet side of the coalescence and separation module, and aeration tube two is fixed on the liquid outflow side of the coalescence and separation module; the lower ends of aeration tube one and aeration tube two are air inlets, and jet holes or grooves are provided in the tube bodies above the air inlets; the tube bodies with jet holes or grooves in aeration tube one and aeration tube two face the coalescence and separation module.

[0024] Preferably, the light phase discharge structure 1 and the light phase discharge structure 2 are both oil bags, and an oil baffle is also provided at the lower side of the light phase discharge structure 1 in the processing space 2 close to the agglomeration and separation module; an exhaust port is provided on the tank body at the cyclone processing space, and a sewage port is provided at the bottom of the tank body at the position of the cyclone processing space close to the enhanced separation module 1.

[0025] Preferably, a backwash water inlet is arranged at the bottom of the tank body near the enhanced separation module 3 at the bottom of the processing space 4; the enhanced separation module 1 and the enhanced separation module 2 are oil removal structures composed of multi-layer straight plates or inclined plates or modified corrugated plates.

[0026] Preferably, the modified corrugated plate is placed at an inclined angle of 45° and adopts a lateral water inlet method; the total length of the processing space in the tank body is L and is set between 6500mm and 6900mm, and the diameter of the tank body is set between 1800mm and 2200mm; the oil-water specific gravity of the produced water entering through the water inlet is set between 0.935 and 0.967; the water inlet of the produced water pre-separation device is connected to the water outlet of the three-phase separator and the drain outlet is connected to the filter.

[0027] The remarkable effects of the present invention are as follows: 1. The present invention adopts a step-by-step, graded, modular oil removal method for oil field produced water, which realizes the agglomeration of oil droplets of different particle sizes before and after treatment in each different treatment space step by step and in sequence, thereby improving the overall agglomeration efficiency of oil droplets. It is a more compact device that can be used with the same produced water pre-separation treatment effect and can reduce the equipment footprint.

[0028] 2. The cyclone mechanism of the present invention uses a flow stabilizing tube. Since the flow stabilizing tube can be inserted into a water collecting tube provided with an inner dehydration tube, and the length of the flow stabilizing tube is greater than the length of the inner dehydration tube, the oil phase in the produced water that passes through the cyclone and ascends along the tube wall of the cyclone tube and gathers at the center of the tube wall can enter the flow stabilizing tube, thereby alleviating the problem of oil droplet divergence caused by the attenuation of the cyclone intensity in the later stage and solving the problem of unstable separation effect caused by further divergence of oil droplets.

[0029] 3. The inner dehydration pipe in the water collecting pipe is a tapered pipe with a small top and a large bottom. The inlet area at the lower end is large and the processing capacity is large. At the same time, multiple cyclone mechanisms can be set in the liquid inlet pipe and multiple liquid inlet pipes equipped with cyclone mechanisms can be connected in parallel with the water inlet, so that the present invention has a higher operating flexibility and adjustment range for the processing capacity of produced water.

[0030] 4. The device of the present invention has the characteristics of compact structure, high separation efficiency for produced water, stable separation effect, etc. It can meet the rapid pretreatment process of produced water short process in offshore oil platforms and other areas and spaces with limited area, is suitable for the petroleum and petrochemical industry and can achieve significant use effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 Schematic diagram of the device of the present invention.

[0032] Figure 2 Cross-sectional view and schematic diagram of the appearance structure of the swirl mechanism.

[0033] Figure 3 Schematic diagram of the structure of the cyclone in the cyclone tube of the cyclone mechanism.

[0034] Figure 4 Schematic diagram of the three-dimensional structure and plane cross-section diagram of the water collecting pipe in the cyclone mechanism.

[0035] Figure 5 Schematic diagram of the structure and three-dimensional structure of the flow stabilizing tube in the swirl mechanism.

[0036] Figure 6 This is a schematic block diagram of the application of the device of the present invention in the produced water treatment process in an offshore platform.

[0037] In the figure: tank body 1, cyclone separation module 2, enhanced separation module 1 3, coalescence separation module 4, aeration pipe 1 41, aeration pipe 2 42, enhanced separation module 2 5; produced water inlet 10, cyclone treatment space 11, sewage outlet 110, treatment space 2 12, treatment space 3 13, treatment space 4 14, sewage outlet 140, drainage outlet 15, light phase discharge structure 1 16, light phase discharge structure 2 17, exhaust port 18, oil baffle 19; cyclone mechanism 20, steady flow pipe 200, water collecting pipe 201, water phase outlet 2011, dehydration inner pipe 2012, water outlet 2013, oil phase outlet 2014, cyclone pipe 202, cyclone 2021, guide section 20211, baffle section 20212, liquid inlet pipe 21; three-phase separator 6, filter 7. Implementation

[0038] The accompanying drawings are for reference and illustration only and are not intended to limit the scope of protection of the present invention. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, in the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0041] See also Figure 1 - Figure 6 , a method for pre-separation of produced water from an oil field that can reduce the floor space is: In the produced water pre-separation device, the separation module isolates independent and interconnected processing spaces in the tank body, allowing the produced water to pass through the set processing spaces one by one and the obtained oil droplet particle size increases step by step, and oil phase layers and water phase layers are formed in the corresponding processing spaces and finally output separately; the produced water pre-separation devices can be connected and combined as needed, and the separation modules in the produced water pre-separation devices can also be installed independently or in combination in the tank body as needed.

[0042] A produced water pre-separation device for an oilfield produced water pre-separation method capable of reducing floor space, comprising a tank body 1, wherein the tank body 1 is provided with a water inlet 10 and a drain outlet 15, wherein: the tank body 1 is mainly divided into independent and interconnected cyclone processing space 11, processing space 2 12, processing space 3 13 and processing space 4 14 by enhanced separation module 1 3, coalescence separation module 4 and enhanced separation module 2 5; the cyclone processing space 11 is provided with a cyclone separation module 2 connected with the water inlet 10, and the processing space 2 12 and the processing space 4 14 are respectively provided with a light phase discharge structure 1 16 and a light phase discharge structure 2 17; the cyclone separation module 2 is provided with a liquid inlet pipe 21 and a cyclone mechanism 2 in which a cyclone 20 is installed. 0, the liquid inlet pipe 21 is connected with the water inlet 10, and the cyclone mechanism 20 is installed in the liquid inlet pipe 21; the produced water of the oil field enters from the water inlet 10, and successively enters the cyclone processing space 11 equipped with the cyclone separation module 2, the processing space 2 12 equipped with the light phase discharge structure 1 16, the processing space 3 13 and the processing space 4 14 equipped with the light phase discharge structure 2 17; the oil phase layer is formed in the processing space 2 12 and the processing space 4 14 and is discharged by the light phase discharge structure 1 16 and the light phase discharge structure 2 17, and the separated water is finally discharged from the drain port 15; the produced water pre-separation devices can be installed independently or in combination; the separation modules in the produced water pre-separation device can also be installed independently or in combination in the tank body 1 as needed.

[0043] Since the cyclone mechanism 20 in the cyclone separation module 2 is equipped with a cyclone 2021, the produced water from the oil field can pass through the cyclone mechanism 20 in a cyclone shape, which can improve the separation effect of oil, gas and water, and the devices of the present invention can be arranged and combined as needed, and the separation modules in the tank body 1 can also be installed independently or in combination, which can significantly reduce the volume of the device of the present invention and greatly reduce its footprint. For example: each separation module is independently installed in the tank body 1, and then connected in series or in parallel by the tank body 1; the separation modules are installed in series or in parallel in the tank body 1, and the tank bodies 1 are connected in series or in parallel; different separation modules are installed in combination in the tank body 1, and the tank bodies 1 are connected in series or in parallel.

[0044] That is, the cyclone separation module 2, enhanced separation module one 3, coalescence separation module 4 and enhanced separation module two 5 can be installed in one tank body 1 or combined in one tank body 1 according to the space that can be occupied by the pre-separation device and the processing capacity of produced water. For example, when four tank bodies 1 are set, the cyclone separation module 2, enhanced separation module one 3, coalescence separation module 4 and enhanced separation module two 5 can be respectively arranged in four tank bodies 1 and connected by pipelines.

[0045] When two tank bodies 1 are provided, the cyclone separation module 2 and the enhanced separation module 1 3 can be arranged in one tank body 1 , and the coalescence separation module 4 and the enhanced separation module 2 5 can be arranged in the other tank body 1 .

[0046] The assembly relationship between each tank body 1 and the separation module installed in the tank body 1 can be further integrated, and the number of any one of the cyclone separation module 2, enhanced separation module 1 3, condensation separation module 4 and enhanced separation module 2 5 installed in the tank body 1 can also be set to be more.

[0047] When the device of the present invention is used in a space-constrained workplace such as an offshore platform, the multiple separation modules in one tank body 1 can achieve the purpose of oil and water separation and separate output, which significantly reduces the floor space and space occupied.

[0048] Since the device of the present invention is provided with a cyclone separation module 2, an enhanced separation module 1 3, a coalescence separation module 4 and an enhanced separation module 2 5, and the inside of the tank body 1 is divided into four completely independent and interconnected processing spaces by the enhanced separation module 1 3, the coalescence separation module 4 and the enhanced separation module 2 5, and three separation modules with different structures and working principles are used for drainage and oil removal, it can process the viscosity of more than 1000 mPa·s and the density of more than 900 kg / m 3 The above heavy oils have very good use effects.

[0049] On the basis of the above-mentioned embodiment 1, the present invention also has the following embodiments: a preferred embodiment: the cyclone mechanism 20 connected to the liquid inlet pipe 21 is arranged at one or more and is connected in series or in parallel with the water inlet 10 through the liquid inlet pipe 21; the cyclone mechanism 20 is also provided with a steady flow pipe 200, a water collecting pipe 201 and a cyclone pipe 202, the water collecting pipe 201 is provided with a dehydration inner pipe 2012, the steady flow pipe 200 can be inserted into the dehydration inner pipe 2012, and the cyclone 2021 is fixed to the lower part of the tube body of the cyclone pipe 202; the steady flow pipe 200, the water collecting pipe 201 and the cyclone pipe 202 are connected from top to bottom by flanges, and the cyclone separation module 2 can be composed of sub-modules consisting of the liquid inlet pipe 21 and the cyclone mechanism 20 in parallel.

[0050] A preferred embodiment: flanges are provided at both ends of the tube body of the water collecting tube 201, the dehydration inner tube 2012 is a tapered tube that is small at the top and large at the bottom and is arranged in an outer sleeve, the two end pipe openings of the tube body of the dehydration inner tube 2012 are respectively connected to the central holes of the flanges at both ends of the water collecting tube 201 and a dehydration cavity is formed between the flanges at both ends of the tube body and the outer sleeve; a water outlet 2013 is provided in the tube body of the dehydration inner tube 2012 and the upper end of the tube body is an oil phase outlet 2014, and a water phase outlet 2011 is provided in the outer sleeve; the flow stabilizing tube 200 can be inserted into the dehydration inner tube 2012 from the oil phase outlet 2014.

[0051] A preferred embodiment: the water outlet holes 2013 are arranged longitudinally in the tube body of the dehydration inner tube 2012 and there are more than six water outlet holes 2013 in each row; the aperture of the water outlet holes 2013 is smaller than the aperture of the water phase outlet 2011, and the inclination angle β between the dehydration inner tube 2012 and the flange end face is 80-85°; the water phase outlet 2011 in the outer sleeve is arranged in more than two.

[0052] A preferred embodiment: a flange is provided on the upper part of the pipe body of the flow stabilizing pipe 200 and the pipe body is divided into an outlet section and a flow stabilizing section by the flange; the length of the flow stabilizing section in the flow stabilizing pipe 200 is greater than the length of the dehydration inner pipe 2012 in the water collecting pipe 201.

[0053] A preferred embodiment: the cyclone 2021 is interference fit with the inner circle of the tube body of the cyclone tube 202, the upper and lower parts of the cyclone 2021 are respectively the deflection section 20212 and the guide section 20211, the outer wall of the body between the deflection section 20212 and the guide section 20211 is a spiral blade, the outer diameter of the deflection section 20212 is smaller than the outer diameters of the spiral blade and the guide section 20211; the outer wall of the body of the guide section 20211 is provided with a longitudinal straight groove connected to the spiral groove in the spiral blade; the angle α between the longitudinal straight groove and the spiral groove in the spiral blade is set between 30 degrees and 60 degrees.

[0054] A preferred embodiment: the coalescence and separation module 4 is a multi-gap oil-aggregating structure formed by weaving oleophilic and hydrophobic fibers or hydrophilic and oleophobic fibers alone or in combination. The multi-gap oil-aggregating structure refers to a multi-gap oil-aggregating structure formed by a porous structure, a multi-groove structure, and a multi-hollow structure, so that small-sized oil droplets in the water phase can fully contact the coalescence and separation module 4, adsorb on the coalescence and separation module 4, and can effectively coalesce into larger-sized oil droplets to further improve the coalescence efficiency. The oleophilic and hydrophobic fibers or hydrophilic and oleophobic fibers are prior art, and reference can be made to the weaving methods and weaving materials disclosed in, for example, CN103952852B or CN103952853B. The coalescence and separation module 4 is an oleophilic and hydrophobic material with a porous structure / multi-hollow structure / multi-gap structure or an interstitial woven material with oleophilic and hydrophobic properties, which can effectively coalesce into larger-sized oil droplets.

[0055] A preferred embodiment: an aeration pipe 1 41 is fixed on the liquid inflow side of the coalescence and separation module 4, and an aeration pipe 2 42 is fixed on the liquid outflow side of the coalescence and separation module 4; the lower ends of the aeration pipe 1 41 and the aeration pipe 2 42 are air inlets, and jet holes or grooves are provided in the pipe bodies above the air inlets; the pipe bodies provided with jet holes or grooves in the aeration pipe 1 41 and the aeration pipe 2 42 face the coalescence and separation module 4.

[0056] By positively pumping air into the air inlet of aeration pipe 1 41, the coalescence separation module 4 can be unblocked; the gas pumped into aeration pipe 2 42 can backwash the coalescence separation module 4 and stir the oil-water separation liquid in the treatment space 3 13, thereby improving the local turbulence capacity during backwashing, enhancing the backwashing effect, and reducing the amount of backwashing liquid required.

[0057] A preferred embodiment: the light phase discharge structure 16 and the light phase discharge structure 2 17 are both oil bags, and an oil baffle 19 is also provided below the side of the light phase discharge structure 16 in the processing space 2 12 close to the coalescence separation module 4; during use, the interface between the oil phase layer and the water phase layer in the processing space 2 12 can be kept not lower than the lowest point of the oil baffle 19. At this time, only the water phase layer below the oil baffle 19 is allowed to pass, and the oil phase layer can be discharged from the light phase discharge structure 16 in front of the oil baffle 19. Similarly, when the precipitated gas exists, the gas is a light phase and is also blocked by the oil baffle 19, so that it is discharged from the light phase discharge structure 16 without entering the next level of processing space. The tank body 1 at the cyclone treatment space 11 is provided with an exhaust port 18. When the produced water passes through the cyclone separation module 2, the pressure is reduced, so that the natural gas in the produced water is precipitated. The exhaust port 18 is provided to discharge the precipitated gas. After the produced water passes through the cyclone separation module 2, the solid suspended matter in the produced water is discharged downward and deposited in the lower part of the cyclone treatment space 11. The bottom of the tank body 1 at the position of the cyclone treatment space 11 near the enhanced separation module 3 is provided with a sewage outlet 110.， To facilitate dredging.

[0058] A preferred embodiment: a backwash water inlet 140 is provided at the bottom of the tank body 1 near the position of the enhanced separation module 3 5 at the bottom of the treatment space 4 14, so as to backwash the treatment space 4 14; the enhanced separation module 1 3 and the enhanced separation module 2 5 are oil removal structures composed of multi-layer straight plates or inclined plates or modified corrugated plates. Among them, the use of modified corrugated plates as the oil removal structure is the best choice. The tortuous channels between the modified corrugated plates can force the water flow to form a special flow state that increases the probability of oil droplet collision, so as to promote the aggregation of small oil droplets.

[0059] A preferred embodiment: the modified corrugated plate is placed at an angle of 45° and adopts a lateral water inlet method to increase the coalescence area; the total length of the treatment space in the tank body 1 is L and is set between 6500mm-6900mm, and the diameter of the tank body 1 is set between 1800mm-2200mm. Among them: the length L1 of the enhanced separation module 1 3, the length L2 of the coalescence separation module 4 and the length L3 of the enhanced separation module 2 5 are consistent and the length of each separation module is set between 10%-15% of the total length L of the treatment space in the tank body 1, so that the treatment efficiency and the overall specifications of the equipment can be better taken into account.

[0060] The oil-water specific gravity of the produced water entering through the water inlet 10 is set between 0.935 and 0.967; the water inlet 10 of the produced water pre-separation device is connected to the water outlet of the three-phase separator 6 and the drain outlet 15 is connected to the filter 7.

[0061] The produced water first enters the three-phase separator 6, and in the present invention, the oil is discharged through the light phase discharge structure 16 and the light phase discharge structure 2 17, and then the water is discharged to the filter 7 through the drain port 15, and then the water is discharged to the production process after filtering. The device of the present invention can replace the existing inclined plate oil remover and aerated flotation device, significantly reducing the floor area and space occupied by the produced water treatment device, and the use effect is remarkable.

[0062] The embodiments described above are only typical embodiments, but the present invention is not limited to these embodiments, and those skilled in the art can make modifications without departing from the spirit and enlightenment of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the creative spirit and creative concept of the present invention should be included in the protection scope of the present invention. Therefore, the protection scope is not limited to the above description.

Claims

1. A method for pre-separating produced water from an oil field which can reduce floor space, characterized in that: In the produced water pre-separation device, the separation module isolates independent and interconnected processing spaces in the tank body, allowing the produced water to pass through the set processing spaces one by one and the obtained oil droplet particle size increases step by step, and forms oil phase layers and water phase layers in the corresponding processing spaces and are finally output separately; the produced water pre-separation devices can be connected and combined as needed, and the separation modules in the produced water pre-separation devices can also be installed independently or in combination in the tank body as needed.

2. A produced water pre-separation device for an oilfield produced water pre-separation method capable of reducing floor space, comprising a tank body (1), wherein the tank body (1) is provided with a water inlet (10) and a water outlet (15), wherein: The tank body (1) is mainly divided into independent and interconnected cyclone processing space (11), processing space 2 (12), processing space 3 (13) and processing space 4 (14) by enhanced separation module 1 (3), coalescence separation module (4) and enhanced separation module 2 (5); the cyclone processing space (11) is provided with a cyclone separation module (2) connected to the water inlet (10); the processing space 2 (12) and the processing space 4 (14) are respectively provided with a light phase discharge structure 1 (16) and a light phase discharge structure 2 (17); the cyclone separation module (2) is provided with a liquid inlet pipe (21) and a cyclone mechanism (20) in which a cyclone (2021) is installed; the liquid inlet pipe (21) is connected to the water inlet (10); the cyclone mechanism (20) is provided with a liquid inlet pipe (21) and a cyclone mechanism (20) in which a cyclone (2021) is installed; Installed in a liquid inlet pipe (21); produced water from the oil field enters from the water inlet (10), and sequentially enters a cyclone processing space (11) equipped with a cyclone separation module (2), a processing space two (12) equipped with a light phase discharge structure one (16), a processing space three (13), and a processing space four (14) equipped with a light phase discharge structure two (17); an oil phase layer is formed in the processing space two (12) and the processing space four (14), and is discharged by the light phase discharge structure one (16) and the light phase discharge structure two (17), and the separated water is finally discharged from the drain port (15); the produced water pre-separation devices can be installed independently or in combination; the separation modules in the produced water pre-separation devices can also be installed independently or in combination in the tank body (1) as required.

3. The produced water pre-separation device according to claim 2, characterized in that: The cyclone mechanism (20) connected to the liquid inlet pipe (21) is arranged at one or more and is connected in series or in parallel with the water inlet (10) through the liquid inlet pipe (21); the cyclone mechanism (20) is further provided with a flow stabilizing pipe (200), a water collecting pipe (201) and a cyclone pipe (202); the water collecting pipe (201) is provided with a dehydration inner pipe (2012); the flow stabilizing pipe (200) can be inserted into the dehydration inner pipe (2012); the cyclone (2021) is fixed to the lower part of the pipe body of the cyclone pipe (202); the flow stabilizing pipe (200), the water collecting pipe (201) and the cyclone pipe (202) are connected from top to bottom via flanges.

4. The produced water pre-separation device according to claim 3, characterized in that: The pipe bodies at both ends of the water collecting pipe (201) are provided with flanges; the dehydration inner pipe (2012) is a tapered pipe that is smaller at the top and larger at the bottom and is arranged in an outer sleeve; the pipe openings at both ends of the pipe body of the dehydration inner pipe (2012) are respectively connected to the central holes of the flanges at both ends of the water collecting pipe (201) and a dehydration cavity is formed between the flanges at both ends of the pipe body and the outer sleeve; the pipe body of the dehydration inner pipe (2012) is provided with a water outlet (213) and the upper end of the pipe body is an oil phase outlet (2014); the outer sleeve is provided with a water phase outlet (211); the flow stabilizing pipe (200) can be inserted into the dehydration inner pipe (2012) from the oil phase outlet (2014).

5. The produced water pre-separation device according to claim 4, characterized in that: The water outlet holes (2013) are arranged longitudinally in the tube body of the dehydration inner tube (2012), and the number of water outlet holes (2013) in each row is more than six; the aperture of the water outlet holes (2013) is smaller than the aperture of the water phase outlet (2011), and the inclination angle β between the dehydration inner tube (2012) and the flange end face is 80-85°; and the number of water phase outlets (2011) in the outer sleeve is more than two.

6. The produced water pre-separation device according to claim 5, characterized in that: The upper part of the pipe body of the flow stabilizing pipe (200) is provided with a flange, and the pipe body is divided into an outlet section and a flow stabilizing section by the flange; the length of the flow stabilizing section in the flow stabilizing pipe (200) is greater than the length of the dehydration inner pipe (212) in the water collecting pipe (201).

7. The produced water pre-separation device according to claim 6, characterized in that: The cyclone (2021) is interference-fitted with the inner circumference of the tube body of the cyclone tube (202); the upper part and the lower part of the cyclone (2021) are respectively a deflection section (20212) and a guide section (20211); the outer wall of the body between the deflection section (20212) and the guide section (20211) is a spiral blade; the outer diameter of the deflection section (20212) is smaller than the outer diameters of the spiral blade and the guide section (20211); the outer wall of the body of the guide section (20211) is provided with a longitudinal straight groove connected to the spiral groove in the spiral blade; the angle α between the longitudinal straight groove and the spiral groove in the spiral blade is set between 30 degrees and 60 degrees.

8. The produced water pre-separation device according to claim 7, characterized in that: The coalescence separation module (4) is a multi-gap oil-coagulating structure formed by weaving oleophilic and hydrophobic fibers or hydrophilic and oleophobic fibers singly or in combination.

9. The produced water pre-separation device according to claim 8, characterized in that: An aeration pipe 1 (41) is fixed to the liquid inflow side of the coalescence separation module (4), and an aeration pipe 2 (42) is fixed to the liquid outflow side of the coalescence separation module (4); the lower ends of the aeration pipe 1 (41) and the aeration pipe 2 (42) are air inlets, and jet holes or grooves are provided in the pipe bodies above the air inlets; the pipe bodies of the aeration pipe 1 (41) and the aeration pipe 2 (42) with the jet holes or grooves face the coalescence separation module (4).

10. The produced water pre-separation device according to claim 9, characterized in that: The light phase discharge structure 1 (16) and the light phase discharge structure 2 (17) are both oil bags, and an oil baffle (19) is also provided below the light phase discharge structure 1 (16) in the processing space 2 (12) on one side close to the agglomeration separation module (4); an exhaust port (18) is provided on the tank body (1) at the cyclone processing space (11), and a sewage outlet (110) is provided at the bottom of the tank body (1) at the position of the enhanced separation module 1 (3) in the cyclone processing space (11).

11. The produced water pre-separation device according to claim 10, characterized in that: A backwash water inlet (140) is provided at the bottom of the tank body (1) near the position of the enhanced separation module (3) at the bottom of the processing space (14); the enhanced separation module (3) and the enhanced separation module (2) (5) are oil removal structures composed of multi-layer straight plates or inclined plates or modified corrugated plates.

12. The produced water pre-separation device according to claim 11, characterized in that: The modified corrugated plate is placed at an angle of 45° and adopts a lateral water inlet method; the total length of the processing space in the tank body (1) is L and is set between 6500 mm and 6900 mm, and the diameter of the tank body (1) is set between 1800 mm and 2200 mm; the oil-water specific gravity of the produced water entering through the water inlet (10) is set between 0.935 and 0.967; the water inlet (10) of the produced water pre-separation device is connected to the water outlet of the three-phase separator (6), and the water outlet (15) is connected to the filter (7).

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