A water pipe type pretreatment device and method for polymer flooding production

Abstract

The present invention discloses a pipe-type pretreatment device and method for polymer flooding production, including a pipe-type hydraulic mixing and flocculation device. A hydraulic mixing and flocculation device outlet pressure transmitter and a separator inlet sampling port are provided on the outlet pipeline of the pipe-type hydraulic mixing and flocculation device, and a chemical dosing assembly is provided in the front section of the pipe-type hydraulic mixing and flocculation device; the outlet pipeline of the pipe-type hydraulic mixing and flocculation device is processed by a low-shear dynamic vortex separator and then leads to a deoiling recovery unit and a produced water advanced treatment unit; the pipe-type hydraulic mixing and flocculation device includes a chemical injection pipe section, a mixing pipe section, and a flocculation trailing vortex plate spacer pipe connected in sequence from the inlet. A mixing trailing vortex plate is provided inside the inlet end of the chemical injection pipe section, and a chemical injection pipe is provided on the side wall. Flocculation trailing vortex plates are respectively provided inside both ends of the flocculation trailing vortex plate spacer pipe. Overall consideration is given to chemical dosing, mixing, flocculation, and rapid separation, and the fragmentation and emulsification of flocs and large oil droplets are avoided in terms of process and the selection of separation equipment.

Description

Technical Field

[0001] The present invention relates to a technology for adding medicine, mixing, flocculating and low-shear dynamic vortex separation of oilfield produced water, and particularly relates to a tubular pretreatment equipment and method for polymer flooding produced water, which can be widely used in the field of oilfield produced water treatment. Background Art

[0002] The produced sewage in oilfields is one of the main sources of industrial sewage. Polymer flooding is the best measure to improve the recovery rate of continental sedimentary oilfields in the high water cut period and the extra-high water cut period. After part of the polymer flooding agent returns, the dispersed oil droplet size in the produced water becomes small, the stability of the oil-water interface film is enhanced, the repulsive force increases, and the difficulty of oil-water separation increases significantly. In order to make the treated sewage meet the reinjection water quality standard, a flocculant is added to the water treatment system to flocculate small oil droplets into large-sized flocs to improve the oil-water separation efficiency. Measures to ensure the compliance of the effluent have been widely used in the polymer flooding oilfield produced water treatment process.

[0003] To give full play to the role of the flocculant, a mixing and flocculating device is needed to complete the full mixing of the medicine and the polymer flooding produced water and promote flocculation. However, the existing mixing and flocculating devices are large in size and long in action time. Most oilfields have to directly inject the medicine into the pipeline and increase the dosage of the medicine to offset the poor mixing effect.

[0004] In the prior art:

[0005] Patent applications such as "Integrated Mixing, Flocculating and Air Flotation Machine" with patent application number CN 109896669 A, "A Re-mixing and Flocculating Device for a Sludge Treatment System" with application number CN103159392A, "Air Flotation and Flocculation Reaction Turbulence Device" with application number CN 217498935 U, and "An Improved Flocculation Reaction Device" with application publication number 217437840U all use a motor-driven agitator paddle in a conventional mixing and flocculating tank to complete the mixing of the medicine and the continuous phase and promote flocculation. This type of mixing and flocculating device and method do not break away from the conventional stirring and mixing and flocculating methods. The mixing and flocculating device is not only large in size but also a moving device, with high operating costs.

[0006] "A Pulsating Medicine Adding, Mixing and Flocculating Precipitation Device" with application publication number CN 114212853 A generates pulses in a coagulation pipe using a bamboo joint-shaped pipe to achieve the mixing and flocculation of the medicine and the continuous medium through the pulses. "A Mixing and Flocculating Device and a Mixing and Flocculating Method" with application publication number CN113772793A completes mixing in a spiral pipe and flocculation in a diffuser pipe. The mixing pipe is up to 6.8 m long and the flocculation pipe has a diameter of 2 m. The device is large in size. For sewage that is prone to generating viscous flocs, the long spiral pipe is prone to fouling. In addition, the optimal hydraulic conditions for mixing and flocculation are not provided, and the process dimensions are given based on experience, making it difficult to promote and apply.

[0007] The flocs formed under the action of the flocculant are easily broken and emulsified again. The characteristic of small oil-water interface tension in the produced liquid of polymer flooding also leads to the easy breakage and emulsification of large oil droplets. In the existing production processes in oilfields, separation and mixing flocculation are regulated as two independent units. Therefore, there will be regulating valves for pressure, flow rate, etc. between the mixing flocculation unit and the separation unit. After the oil, water, and floc mixture after flocculation passes through these valves, under the throttling and shearing action of the valves, it will inevitably lead to the breakage and emulsification of the flocs and large oil droplets, thereby reducing the effect of the chemical agent and increasing the separation difficulty.

[0008] To sum up, the mechanical stirring and chemical dosing mixing flocculation equipment has a large volume, requires a power source, and has high operation and maintenance costs. While for the hydraulic mixing flocculation equipment, there is no clear calculation method for hydraulic conditions, and it is difficult to promote the size of the mixing equipment determined by empirical values. In terms of application, the current oilfield production water treatment process does not comprehensively consider the chemical dosing mixing flocculation and separation equipment, and it has become difficult to solve the new problems brought by polymer flooding oilfields.

[0009] In view of this, the present invention is specifically proposed. Summary of the Invention

[0010] The purpose of the present invention is to provide a tubular pretreatment equipment and method for polymer flooding production water to solve the above technical problems existing in the prior art.

[0011] The purpose of the present invention is achieved through the following technical solutions:

[0012] The tubular pretreatment equipment for polymer flooding production water of the present invention includes a tubular hydraulic mixing flocculator 7. An inlet flow regulating valve 1, an inlet flowmeter 2, and an inlet pressure transmitter 3 are successively arranged on the inlet pipeline of the tubular hydraulic mixing flocculator 7. A hydraulic mixing flocculator outlet pressure transmitter 9 and a separator inlet sampling port 10 are arranged on the outlet pipeline of the tubular hydraulic mixing flocculator 7. A chemical dosing assembly is arranged in the front section of the tubular hydraulic mixing flocculator 7;

[0013] The inlet pipeline of the tubular hydraulic mixing flocculator 7 is connected to the polymer flooding production water, and the outlet pipeline is branched into two branches after being separated by a low-shear dynamic vortex separator 15:

[0014] One branch goes to the decontaminated oil recovery unit, and an oil discharge port pressure transmitter 16 and an oil discharge port flow regulating valve 17 are arranged on the pipeline;

[0015] The other branch goes to the production water advanced treatment unit, and a water outlet flowmeter 11, a water outlet pressure transmitter 12, a water outlet flow regulating valve 13, and a water outlet sampling port 14 are arranged on the pipeline.

[0016] The method for realizing the pretreatment of polymer flooding production water by the above-mentioned tubular pretreatment equipment for polymer flooding production water includes:

[0017] The polymer flooding produced water entering the tubular hydraulic mixing and flocculation device 7 forms a strongly unstable Karman vortex street with a velocity gradient of 1430 s -1 after passing through the mixing trailing vortex plate 18. The chemical agent is injected at the first vortex street after the mixing trailing vortex plate 18, and rapid mixing is completed within a distance of 5d i by utilizing the strongly unstable vortex street;

[0018] The chemical agent is injected into the polymer flooding produced water. After mixing and passing through the flocculation trailing vortex plate 21, a weakly unstable Karman vortex street with a velocity gradient of 900 s -1 is formed to promote flocculation and enhance the density of the flocs;

[0019] The polymer flooding produced water containing flocs directly enters the low-shear dynamic vortex separator 15 to ensure the integrity of the easily broken flocs, improve the separation efficiency, and rapidly complete the separation of the flocs;

[0020] After separation, the water phase and the oil phase respectively enter the produced water advanced treatment unit and the waste oil recovery unit. A water outlet flow regulating valve 13 and an oil discharge port flow regulating valve 17 are respectively arranged on the water outlet pipeline and the oil discharge pipeline to regulate the water discharge volume and the oil discharge volume;

[0021] Sampling ports are respectively arranged on the inlet pipeline, the water outlet pipeline, and the oil discharge pipeline of the low-shear dynamic vortex separator 15 for sampling and analyzing the quality of the incoming liquid and the treated water quality.

[0022] Compared with the prior art, the polymer flooding produced water tubular pretreatment equipment and method provided by the present invention are based on hydraulic mixing and flocculation and low-shear dynamic vortex separation, overall considering chemical dosing, mixing, flocculation, and rapid separation, and avoiding the fragmentation and emulsification of flocs and large oil droplets in terms of process and separation equipment selection. Among them, the mixing and flocculation equipment can achieve rapid mixing and efficient flocculation of polymer flooding produced water and chemical agents, and has the characteristic of preventing fouling by viscous flocs. Description of the Drawings

[0023] Figure 1 is a schematic flow field diagram of the polymer flooding produced water tubular pretreatment equipment and method provided by the embodiment of the present invention.

[0024] Figure 2 is Figure 1 a sectional view of the tubular mixing and flocculation device 7 in

[0025] Figure 3 is Figure 2 a front view of the mixing trailing vortex plate 18 of the tubular mixing and flocculation device in

[0026] Figure 4 is Figure 3 a sectional view of the mixing trailing vortex plate in the A-A direction in

[0027] Figure 5 is Figure 2Front view of the flocculation trailing vortex plate 21 of the middle tube type mixing flocculator;

[0028] Figure 6 For Figure 5 Cross-sectional view of the middle flocculation trailing vortex plate in the B-B direction

[0029] The components corresponding to the labels in the figure are:

[0030] 1 - Inlet flow regulating valve, 2 - Inlet flowmeter, 3 - Inlet pressure transmitter, 4 - Pressure transmitter for chemical injection pipeline, 5 - Check valve, 6 - Chemical inlet on-off valve, 7 - Tube type hydraulic mixing flocculator, 8 - Diaphragm metering pump, 9 - Separator inlet pressure transmitter, 10 - Separator inlet sampling port, 15 - Low shear dynamic vortex separator, 11 - Separator water outlet flowmeter, 12 - Separator water outlet pressure transmitter, 13 - Separator water outlet flow regulating valve, 14 - Separator water outlet sampling port, 16 - Separator oil drain port pressure transmitter, 17 - Separator oil drain port flow regulating valve, 18 - Mixing trailing vortex plate, 19 - Chemical injection pipe, 20 - Mixing pipe section, 21 - Flocculation trailing vortex plate, 22 - Flocculation trailing vortex plate spacer tube. Specific embodiments

[0031] The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments, which does not constitute a limitation to the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0032] First, the following explanations are given for the terms that may be used in this article:

[0033] The term "and / or" means that either one of the two or both can be achieved. For example, X and / or Y means that it includes both the cases of "X" or "Y" and the case of "X and Y".

[0034] The description of terms such as "including", "containing", "having", or other similar semantics should be interpreted as non-exclusive inclusion. For example: including a certain technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction condition, processing condition, parameter, algorithm, signal, data, product or article, etc.) should be interpreted as not only including the clearly listed certain technical feature element, but also including other well-known technical feature elements in the art that are not clearly listed.

[0035] The term "consisting of" means excluding any technical feature elements not explicitly listed. If this term is used in a claim, the claim will be a closed - type claim, excluding technical feature elements other than those explicitly listed, except for conventional impurities related thereto. If this term only appears in a sub - clause of a claim, it only limits the elements explicitly listed in that sub - clause, and the elements described in other sub - clauses are not excluded from the overall claim.

[0036] Unless otherwise explicitly specified or limited, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this text can be understood according to specific circumstances.

[0037] The orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counter - clockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of description and simplification of the description, rather than explicitly or implicitly indicating that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to this text.

[0038] The content not described in detail in the embodiments of the present invention belongs to the prior art well - known to those of ordinary skill in the art. For those conditions not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the art or the conditions recommended by the manufacturer. For the reagents or instruments not indicating the manufacturer in the embodiments of the present invention, they are all conventional products that can be obtained through commercial purchase.

[0039] The polymer - flooding production water pipe - type pretreatment equipment of the present invention includes a tubular hydraulic mixing and flocculation device 7. An inlet flow regulating valve 1, an inlet flowmeter 2, and an inlet pressure transmitter 3 are successively arranged on the inlet pipeline of the tubular hydraulic mixing and flocculation device 7. A hydraulic mixing and flocculation device outlet pressure transmitter 9 and a separator inlet sampling port 10 are arranged on the outlet pipeline of the tubular hydraulic mixing and flocculation device 7. A chemical dosing assembly is arranged in the front section of the tubular hydraulic mixing and flocculation device 7;

[0040] The inlet pipeline of the tubular hydraulic mixing and flocculation device 7 is connected to the polymer - flooding production water, and the outlet pipeline is branched into two after passing through a low - shear dynamic vortex separator 15:

[0041] An oil removal and recovery unit, and an oil discharge port pressure transmitter 16 and an oil discharge port flow regulating valve 17 are provided on the pipeline;

[0042] Another one goes to the advanced treatment unit for production water, and a water outlet flowmeter 11, a water outlet pressure transmitter 12, a water outlet flow regulating valve 13, and a water outlet sampling port 14 are provided on the pipeline.

[0043] The chemical dosing assembly includes a chemical injection pressure transmitter 4, a check valve 5, a chemical inlet switch valve 6, and a diaphragm metering pump 8 connected in sequence.

[0044] The tubular hydraulic mixing and flocculation device 7 includes an injection pipe section, a mixing pipe section 20, and a flocculation trailing vortex plate spacer pipe 22 connected in sequence from the inlet;

[0045] The inner part of the inlet end of the injection pipe section is provided with a mixing trailing vortex plate 18, the side wall of the injection pipe section is provided with a chemical injection pipe 19, the chemical injection pipe 19 is connected to the chemical dosing assembly, and flocculation trailing vortex plates 21 are respectively arranged inside both ends 22 of the flocculation trailing vortex plate spacer pipe.

[0046] The distance L3 from the chemical injection pipe 19 to the inlet of the mixing trailing vortex plate 18 after the mixing trailing vortex plate 18 is 0 to d / 6; i / 6;

[0047] The flocculation trailing vortex plate 21 at the front end of the flocculation trailing vortex plate spacer pipe 22 is arranged after the mixing pipe section 20, and the distance L1 from the inlet of the mixing trailing vortex plate 18 is not less than 5d; i at;

[0048] The distance L2 between the flocculation trailing vortex plates 21 at both ends of the flocculation trailing vortex plate spacer pipe 22 is not less than 2d; i ;

[0049] d i is the inner diameter of the pipeline of the tubular hydraulic mixing and flocculation device 7, that is, the inner diameters of the mixing pipe section 20 and the flocculation trailing vortex plate spacer pipe 22.

[0050] The outer diameter of the mixing trailing vortex plate 18 is the same as the inner diameter d of the mixing pipe section 20, and S i is the area of the hollow region of the mixing trailing vortex plate in the axial projection: hm ;

[0051] At this time, the velocity gradient G = 1430 s -1 ; where Q is the treatment capacity, m 3 / s; ρ is the density of the mixed liquid, kg / m 3 ; μ is the viscosity of the mixed liquid, Pa·s;

[0052] The outer diameter of the flocculation trailing vortex plate 21 is the same as the inner diameter d of the flocculation trailing vortex plate spacer pipe 22i Same, S hc is the hollow area of the flocculation trailing vortex plate in the axial projection:

[0053] At this time, the velocity gradient G = 900 s -1 .

[0054] The mixing trailing vortex plate 18 is inclined 10° in the flow direction, and the flocculation trailing vortex plate 21 is inclined 30° in the flow direction.

[0055] The method for realizing the pretreatment of polymer flooding produced water by the above-mentioned polymer flooding produced water pipe-type pretreatment equipment includes:

[0056] The polymer flooding produced water entering the tubular hydraulic mixing and flocculation device 7 forms a strongly unstable Karman vortex street with a velocity gradient of 1430 s after passing through the mixing trailing vortex plate 18. The chemical agent is injected at the first vortex street after the mixing trailing vortex plate 18, and rapid mixing is completed within a distance of 5d by using the strongly unstable vortex street; -1 of the strongly unstable Karman vortex street. The chemical agent is injected into the polymer flooding produced water, and after mixing, it forms a weakly unstable Karman vortex street with a velocity gradient of 900 s after passing through the flocculation trailing vortex plate 21, promoting flocculation and enhancing the density of the flocs; i The polymer flooding produced water containing flocs directly enters the low-shear dynamic vortex separator 15 to ensure the integrity of the easily broken flocs, improve the separation efficiency, and quickly complete the separation of the flocs;

[0057] After separation, the water phase and the oil phase respectively enter the produced water advanced treatment unit and the waste oil recovery unit. A water outlet flow regulating valve 13 and an oil discharge port flow regulating valve 17 are respectively arranged on the water outlet pipeline and the oil discharge pipeline to regulate the drainage volume and the oil discharge volume; -1 The low-shear dynamic vortex separator 15 is provided with sampling ports on the inlet pipeline, the water outlet pipeline and the oil discharge pipeline respectively for sampling and analyzing the quality of the incoming liquid and the treated water quality.

[0058] No regulating valve is arranged between the tubular hydraulic mixing and flocculation device 7 and the low-shear dynamic vortex separator 15.

[0059] The processes of chemical addition and mixing, flocculation and separation are completed in the tubular hydraulic mixing and flocculation device 7 and the low-shear dynamic vortex separator 15, and the total hydraulic retention time does not exceed 20 s.

[0060] Sampling ports are respectively arranged on the inlet pipeline, the water outlet pipeline and the oil discharge pipeline of the low-shear dynamic vortex separator 15 for sampling and analyzing the quality of the incoming liquid and the treated water quality.

[0061] No regulating valve is arranged between the tubular hydraulic mixing and flocculation device 7 and the low-shear dynamic vortex separator 15.

[0062] The processes of chemical addition and mixing, flocculation and separation are completed in the tubular hydraulic mixing and flocculation device 7 and the low-shear dynamic vortex separator 15, and the total hydraulic retention time does not exceed 20 s.

[0063] In summary, the tube-type pretreatment equipment and method for polymer flooding production water according to the embodiments of the present invention are based on hydraulic mixing flocculation and low-shear dynamic vortex separation, comprehensively considering chemical dosing, mixing flocculation, and rapid separation. From the selection of the process and separation equipment, the crushing and emulsification of flocs and large oil droplets are avoided. The mixing flocculation equipment can achieve rapid mixing and efficient flocculation of polymer flooding produced water and chemicals, and has the characteristic of preventing fouling caused by viscous flocs.

[0064] The tube-type pretreatment process for polymer flooding production water based on hydraulic mixing flocculation and low-shear dynamic vortex separation according to the embodiments of the present invention completes the rapid mixing and efficient flocculation of polymer flooding production water and flocculant based on hydraulic conditions, and uses a low-shear dynamic vortex separator to complete the second-level separation of flocs. Taking the tube-type mixing flocculator and the low-shear dynamic vortex separator as a unit, without setting any regulating valves in the middle, and all regulating valves are set at the inlet of the tube-type mixing flocculator and the outlet of the low-shear dynamic vortex separator, effectively solving the problem that it is difficult to separate the flocs and oil droplets in polymer flooding production water due to easy breakage, and the total hydraulic retention time of chemical dosing, mixing flocculation, and pre-separation is not more than 20 s. The provided key design - the tube-type mixing flocculator uses the unstable Karman vortex street generated by the trailing vortex plate to complete mixing or flocculation. By adjusting the area of the hollow area of the trailing vortex plate, strong mixing vortex streets with a velocity gradient of 1430 s -1 and weak flocculation vortex streets with a velocity gradient of 900 s- 1 are respectively formed, and the flocculant is added after the mixing trailing vortex plate. By adopting the above structure, the tube-type mixing flocculator has only one mixing element and two flocculation elements. When a viscous colloid is produced after mixing, only one mixing element can be used to prevent fouling. Through the above structure, the hydraulic mixing and flocculation of chemicals and polymer flooding production water are realized, and the inner diameter of the equipment is the same as that of the process pipeline, realizing complete tubulation.

[0065] In order to more clearly show the technical solutions provided by the present invention and the technical effects produced, the following uses specific embodiments to describe in detail what is provided by the embodiments of the present invention.

[0066] Embodiment 1

[0067] As Figures 1 to 6 shown, the embodiment of the present invention provides a tube-type pretreatment process for polymer flooding production water based on hydraulic mixing flocculation and low-shear dynamic vortex separation, which can realize the rapid separation of chemical dosing, mixing flocculation, and low-shear of production water, including:

[0068] Inlet flow regulating valve 1, inlet flowmeter 2, inlet pressure transmitter 3, chemical injection pressure transmitter 4, check valve 5, chemical inlet switch valve 6, tubular hydraulic mixing flocculator 7, diaphragm metering pump 8, hydraulic mixing flocculator outlet pressure transmitter 9, separator inlet sampling port 10, low-shear dynamic vortex separator 15, water outlet flowmeter 11, water outlet pressure transmitter 12, water outlet flow regulating valve 13, water outlet sampling port 14, oil drain port pressure transmitter 16, oil drain port flow regulating valve 17; among them,

[0069] An inlet flow regulating valve (1), an inlet flowmeter 2, and an inlet pressure transmitter 3 are arranged on the inlet pipeline of the tubular hydraulic mixing flocculator 7. The diaphragm metering pump 8 is connected to the tubular hydraulic mixing flocculator 7 through a check valve 5 and a chemical inlet switch valve 6;

[0070] The inlet of the low-shear dynamic vortex separator 15 is connected to the outlet of the tubular hydraulic mixing flocculator 7. A hydraulic mixing flocculator outlet pressure transmitter 9 and a separator inlet sampling port 10 are arranged on the connecting pipeline. The water discharged from the low-shear dynamic vortex separator 15 is discharged into the production water advanced treatment unit. A water outlet flowmeter 11, a water outlet pressure transmitter 12, a water outlet flow regulating valve 13, and a water outlet sampling port 14 are arranged on the outlet pipeline. The high-water-content oil phase separated by the low-shear dynamic vortex separator 15 is discharged into the waste oil recovery unit. An oil drain port pressure transmitter 16 and an oil drain port flow regulating valve 17 are arranged on the drain pipeline;

[0071] The polymer flooding produced water entering the tubular hydraulic mixing flocculator 7 forms a strong unstable Karman vortex street with a velocity gradient of 1430 s -1 after passing through the mixing trailing vortex plate 18. The chemical is injected at the center of the first vortex street after the mixing trailing vortex plate 18, and the strong unstable Karman vortex street is used to complete rapid mixing within a distance of 5d i For example, for the produced water with a treatment capacity of 10000 m 3 / d, the diameter d i of the mixer is 250 mm, and the mixing distance is 1250 mm;

[0072] The mixture of the flocculant and the polymer flooding produced water forms a weaker unstable Karman vortex street with a velocity gradient of 900 s -1 after passing through the flocculation trailing vortex plate 21, and the hydraulic environment is used to promote flocculation and improve the density of the flocs;

[0073] The polymer flooding produced water containing flocs directly enters the low-shear dynamic vortex separator 15 to ensure the integrity of the easily broken flocs, and then realizes the efficient and rapid separation of the flocs;

[0074] After separation, the aqueous phase and the oil phase enter the advanced treatment unit for produced water and the waste oil recovery unit respectively. Water outlet flow regulating valves 13 and oil drain outlet flow regulating valves 17 are respectively arranged on the water outlet pipeline and the oil drain pipeline to regulate the water discharge and the oil discharge volume.

[0075] Sampling ports are respectively arranged on the inlet pipeline, the water outlet pipeline and the oil drain pipeline of the low-shear dynamic vortex separator 15 for sampling and analyzing the quality of the incoming liquid and the treated water quality.

[0076] In the above process, the tubular hydraulic mixing flocculator 7 and the low-shear dynamic vortex separator 15 are regarded as a unit, and the regulating valves are arranged at the inlet of the tubular hydraulic mixing flocculator 7 and the outlet of the low-shear dynamic vortex separator 15.

[0077] In the above process, no regulating valve is arranged on the pipeline between the tubular hydraulic mixing flocculator 7 and the low-shear dynamic vortex separator 15.

[0078] In the embodiment of the present invention, the key equipment for tubular pretreatment of polymer flooding production water based on hydraulic mixing flocculation and low-shear dynamic vortex separation is the tubular hydraulic mixing flocculator 7, including:

[0079] Mixed trailing vortex plate 18, chemical injection pipe 19, mixing pipe section 20, flocculation trailing vortex plate 21, flocculation trailing vortex plate spacer pipe 22;

[0080] The mixed trailing vortex plate 18 is fixedly installed at the inlet end of the tubular hydraulic mixing flocculator 7, and the flocculant injection pipe 19 is arranged at a distance L3 from the mixed trailing vortex plate 18 behind the mixed trailing vortex plate, and the distance is d i / 6;

[0081] The flocculation trailing vortex plate 21 is arranged after the mixing pipe section 20, and the distance L1 from the inlet of the mixed trailing vortex plate 18 is not less than 5d i ;

[0082] Both ends of the flocculation trailing vortex plate spacer pipe 22 are respectively installed with the flocculation trailing vortex plate 21, and the distance L2 between the flocculation trailing vortex plates is not less than 2di;

[0083] The outer diameter d of the mixed trailing vortex plate 18 i is the same as the inner diameter of the mixing pipe, and S hm is the hollow area of the mixed trailing vortex plate in the axial projection, and when a better mixing is achieved the velocity gradient G = 1430s -1 , where Q is the treatment volume, m 3 / s, ρ is the density of the mixed liquid, kg / m 3 , and μ is the viscosity of the mixed liquid, Pa·s;

[0084] The outer diameter di of the flocculation trailing vortex plate 21 is the same as the inner diameter of the process pipeline. Shc is the hollow area of the flocculation trailing vortex plate in the axial projection, achieving a better flocculation effect At this time, the velocity gradient G = 900 s -1 ;

[0085] The mixing trailing vortex plate of the mixing trailing vortex plate 18 is inclined 10° along the flow direction to obtain a strong unstable Karman vortex street for rapid mixing;

[0086] The flocculation trailing vortex plate of the flocculation trailing vortex plate 21 is inclined 30° along the flow direction to reduce the turbulent shear caused by the throttling effect, promote flocculation and avoid the breakage of the produced flocs.

[0087] In the above equipment, an unstable Karman vortex street is generated by the obstacle flow to complete mixing and promote flocculation.

[0088] In the above equipment, the exact calculation formula of the hollow area of the mixing trailing vortex plate and the flocculation trailing vortex plate after axial projection is obtained from the velocity gradient value.

[0089] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0090] (1) Considering the dosing mixing flocculation and pre-separation as a whole, the flocs do not break: The dispersed phase of the polymer flooding production water is severely emulsified. The flocs generated after dosing are more likely to break and once broken, they cannot be flocculated again. Therefore, a low-shear dynamic vortex separator is preferably used to avoid the breakage of the flocs caused by shear. The dosing mixing flocculation equipment is designed as an integrated process unit. The inlet control regulating valve is set at the inlet end of the tubular mixing flocculator, and the outlet control regulating valve is set at the outlet of the tubular low-shear vortex separator, avoiding the possibility of the flocs being sheared and broken during the transportation to the separator from the process.

[0091] (2) The treatment unit is completely tubular, with small floor area and low operating weight of the process equipment: Facing the rapid development of offshore oil, offshore oilfields have also begun to adopt polymer flooding technology. Tubular treatment can meet the requirements of small space and low load on offshore oil production platforms.

[0092] (3) Through the different velocity gradients required for mixing and flocculation, the exact calculation formula for the hollow area of the components in the mixing and flocculation zones is obtained: The strong unstable Karman vortex street with a velocity gradient of 1430 s generated by 1 simple mixing trailing vortex plate completes mixing, and the weak unstable Karman vortex street with a velocity gradient of 900 s generated by 2 flocculation trailing vortex plates promotes flocculation. The mixing and flocculation are separately regulated, with simple structure and low energy consumption. -1 to complete mixing, and the weak unstable Karman vortex street with a velocity gradient of 900 s generated by 2 flocculation trailing vortex plates promotes flocculation. The mixing and flocculation are separately regulated, with simple structure and low energy consumption. -1

[0093] As described above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims. The information disclosed in the background art part of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art known to those skilled in the art.

Claims

1. A water pipe type pretreatment device for polymer flooding production, characterized in that It includes a tubular hydraulic mixing and flocculation device (7). An inlet flow regulating valve (1), an inlet flowmeter (2), and an inlet pressure transmitter (3) are successively arranged on the inlet pipeline of the tubular hydraulic mixing and flocculation device (7). A hydraulic mixing and flocculation device outlet pressure transmitter (9) and a separator inlet sampling port (10) are arranged on the outlet pipeline of the tubular hydraulic mixing and flocculation device (7). A chemical dosing assembly is arranged in the front section of the tubular hydraulic mixing and flocculation device (7). The inlet pipeline of the tubular hydraulic mixing and flocculation device (7) is connected to polymer flooding produced water. The outlet pipeline is divided into two branches after being processed by a low-shear dynamic vortex separator (15): One branch goes to the decontaminated oil recovery unit, and an oil discharge port pressure transmitter (16) and an oil discharge port flow regulating valve (17) are arranged on the pipeline. The other branch goes to the produced water advanced treatment unit, and a water outlet flowmeter (11), a water outlet pressure transmitter (12), a water outlet flow regulating valve (13), and a water outlet sampling port (14) are arranged on the pipeline. The chemical dosing assembly includes a chemical injection pressure transmitter (4), a check valve (5), a chemical inlet switching valve (6), and a diaphragm metering pump (8) connected in sequence. The tubular hydraulic mixing and flocculation device (7) includes an injection pipe section, a mixing pipe section (20), and a flocculation trailing vortex plate spacer pipe (22) connected in sequence from the inlet. A mixing trailing vortex plate (18) is arranged inside the inlet end of the injection pipe section. A chemical injection pipe (19) is arranged on the side wall of the injection pipe section. The chemical injection pipe (19) is connected to the chemical dosing assembly. Flocculation trailing vortex plates (21) are respectively arranged inside both ends of the flocculation trailing vortex plate spacer pipe (22). The medicament injection pipe (19) is arranged behind the mixing wake plate (18), and the distance L3 from the inlet of the mixing wake plate (18) is 0 to d / 6; i / 6; The flocculation trailing vortex plate (21) at the front end of the flocculation trailing vortex plate spacer tube (22) is arranged behind the mixing pipe section (20), and the distance L1 from the entrance of the mixing trailing vortex plate (18) is not less than 5d i ; The distance L2 between the flocculation trailing vortex plates (21) at both ends of the flocculation trailing vortex plate spacer tube (22) is not less than 2d i ; d i is the inner diameter of the pipe of the tubular hydraulic mixing and flocculation device (7), i.e., the inner diameters of the mixing pipe section (20) and the flocculation trailing vortex plate spacer pipe (22); The outer diameter of the said hybrid wake vane (18) is the same as the inner diameter d of the hybrid pipe section (20). i S hm is the area of the hollow region in the axial projection of the hybrid wake vane: At this time, the velocity gradient G = 1430 s -1 ; where Q is the treatment volume, m 3 / s; ρ is the density of the mixed liquid, kg / m 3 ; μ is the viscosity of the mixed liquid, Pa·s; The outer diameter of the flocculation trailing vortex plate (21) is the same as the inner diameter d of the flocculation trailing vortex plate spacer tube (22). i S hc is the area of the hollow region in the axial projection of the flocculation trailing vortex plate: At this time, the velocity gradient G = 900 s -1 ; The mixing trailing vortex plate (18) is inclined 10° along the flow direction, and the flocculation trailing vortex plate (21) is inclined 30° along the flow direction.

2. A method for realizing pretreatment of polymer flooding production water by the tubular pretreatment equipment for polymer flooding production water according to claim 1, characterized in that, It includes: The polymer flooding produced water entering the tubular hydraulic mixing and flocculation device (7) forms a strongly unstable Karman vortex street with a velocity gradient of 1430 s -1 after passing through the mixing trailing vortex plate (18). The chemical agent is injected at the first vortex street after the mixing trailing vortex plate (18), and rapid mixing is completed within a distance of 5 d i by utilizing the strongly unstable vortex street; The medicament is injected into the polymer flooding produced water. After mixing, a relatively weak and unstable Karman vortex street with a velocity gradient of 900 s -1 is formed after passing through the flocculation trailing vortex plate (21), which promotes flocculation and improves the density of the flocs; The polymer flooding produced water containing flocs directly enters the low-shear dynamic vortex separator (15) to ensure the integrity of easily broken flocs, improve the separation efficiency, and quickly complete the separation of flocs. After separation, the water phase and the oil phase respectively enter the produced water advanced treatment unit and the decontaminated oil recovery unit. A water outlet flow regulating valve (13) and an oil discharge port flow regulating valve (17) are respectively arranged on the outlet water pipeline and the oil discharge pipeline to regulate the water discharge volume and the oil discharge volume. Sampling ports are respectively arranged on the inlet pipeline, the water outlet pipeline, and the oil discharge pipeline of the low-shear dynamic vortex separator (15) for sampling and analyzing the quality of the incoming liquid and the treated water quality.

3. The method for pre-treating produced water in polymer flooding production according to claim 2, wherein, No regulating valve is arranged between the tubular hydraulic mixing and flocculation device (7) and the low-shear dynamic vortex separator (15).

4. The method for pre-treating produced water in polymer flooding production according to claim 3, characterized in that The processes of chemical dosing and mixing, flocculation, and separation are completed in the tubular hydraulic mixing and flocculation device (7) and the low-shear dynamic vortex separator (15), and the total hydraulic retention time does not exceed 20 s.

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