Two-section double-gradient three-electric-field enhanced demulsification three-phase separator and method

Abstract

The invention discloses a two-section double-gradient three-electric-field enhanced demulsification three-phase separator and method. The separator comprises a tank body, a tubular distributor, a crude oil pipeline, a dosing pipeline, an oil outlet pipeline, a gas outlet pipeline, a multi-electric-field power supply device and heating equipment (optional), a first section, a second section, a crude oil collecting section and other crude oil treatment areas are arranged in the separator. The high-frequency / high-voltage insulated electrode is located in the oil-rich layer and the emulsion layer and located in the middle of the section; the ultrahigh-frequency / low-voltage bare electrode is positioned in the liquid phase layer of one section; the high-frequency / high-voltage bipolar bare electrode is positioned in the oil-rich layer of the second section; the existing thermochemical treatment process of the crude oil is simplified, the three electric fields can perform effective electric field demulsification and electrostatic coalescence dehydration on the crude oil with corresponding water content in the tank, the chemical demulsification process in the electric fields can be enhanced, the retention time of conventional high-frequency pulsed electric field treatment of the crude oil is shortened, and closed, efficient and low-cost treatment of the crude oil can be realized.

Description

Technical Field

[0001] The present invention relates to a three-phase separation technology, and in particular to a two-stage double-gradient three-electric field enhanced demulsification three-phase separator and method, which are used for demulsifying and dehydrating crude oil so that the treated crude oil meets the external transmission standard in the mine or meets the relevant requirements of the subsequent processing standard in the refinery. Background Art

[0002] As the economy enters a stage of rapid development, the demand for energy continues to increase, and the exploitable life of oil and gas resources is getting shorter and shorter. It is urgent to find new alternative energy sources. Once discovered, oil shale, as an alternative energy source to petroleum, has become the focus of world attention.

[0003] Shale oil refers to the oil resources contained in shale formations (mainly shale), which mainly exist in rock pores, cracks, adjacent layers and interlayers. Shale oil has the characteristics of high freezing point, high wax content, high wax precipitation point, small droplet size in emulsion, and high emulsification degree. Therefore, shale oil produced fluid has problems such as demulsification and dehydration difficulties during the treatment process. In order to meet the needs of shale oil mine product measurement, mine processing, commercial crude oil quality requirements, crude oil storage and pipeline (or other transportation methods) transportation, the gas and liquid phases must be separated, and the crude oil and associated water in the liquid phase must be separated. Therefore, three-phase separation treatment has become the primary processing procedure for shale oil processing in mines.

[0004] Oil, gas and water have different physical and chemical properties, such as density and viscosity. The oil, gas and water three-phase separator uses a certain method (such as gravity sedimentation, centrifugal method, packing separation method, etc.) to make use of the different properties of the three phases to achieve a certain degree of separation of oil, gas and water. However, due to the different properties of the produced fluids in various oil fields, the degree of separation required for the three phases of oil, gas and water is also different. Therefore, domestic and foreign scholars and engineering and technical personnel continue to study, design and improve the oil, gas and water three-phase separator according to the requirements of production and mining environment, making it more reasonable, effective, economical and environmentally friendly.

[0005] Since 2017, Professor Chen Jiaqing's research group at Beijing Institute of Petrochemical Technology has been committed to the localization of the third-generation VIEC technology and products. After more than two years, on the basis of fully digesting and absorbing the third-generation VIEC electric field demulsification technology from abroad, the transformer non-built-in VIEC electrostatic agglomeration module was independently developed. The module consists of metal electrodes, insulating electrodes, stainless steel pipes and collection balls, and the insulating electrode plate is integrally molded by epoxy resin material. The technology was pilot-tested at the Zhuanxi 106 transfer station of Shengli Oilfield in January 2019. The water content at the inlet of the three-phase separator was 97.3%, the crude oil density was 0.932g / cm3, and the viscosity was 328mPa·s. The experimental results show that under the action of high-frequency / high-voltage pulsed AC electric field, the VIEC electric field demulsification technology can reduce the water content of oil well produced fluid with a water content of 97% to about 4% or even lower after electrostatic agglomeration and dehydration. The electric field demulsification effect is significant, which provides valuable experience for subsequent industrial field application experimental research.

[0006] In 2020, Liu Cunxin and others from Jinbiao Intelligent Technology Co., Ltd. proposed a new type of high-frequency electrostatic coalescer. When working, the high-water crude oil emulsion enters from the tangential inlet of the gas-liquid cyclone separator. After the internal cyclone centrifugation, the gas is discharged from the upper exhaust pipe, and the liquid flows into the electric field area from the lower part of the device. The crude oil emulsion is subjected to electric field demulsification by the first-level high-frequency coalescing device, so that the high-water crude oil emulsion can achieve the purpose of oil-water separation: the second-layer coalescing device in the device can effectively cut the bubbles, improve the transfer rate and utilization efficiency of oxygen, so that the organic matter in the water can be effectively treated. In the same year, Sun Longlong and others from Shengli Oilfield Longxi Petroleum Engineering Service Co., Ltd. designed a high-frequency coalescing device to address the problems of strong emulsification and difficult treatment of high-water crude oil production fluid. During the treatment process, the crude oil emulsion enters through the inlet and is evenly dispersed in the tank through the oil hole distributor, flows through the electric field area, and under the action of the electric field of the electrode grid, the oil and water phases are separated, and the oil phase is discharged from the tank through the oil outlet. Field test results show that after treatment, the water content of crude oil emulsion with a water content of more than 90% can be reduced to 5%, and the effect of electric field demulsification and pre-water separation is significant.

[0007] In summary, in the existing three-phase separation process of crude oil, the thermochemical process has high cost, long processing flow, and is difficult to seal, resulting in large oil and gas losses, prominent environmental problems, and it is difficult for the treated oil and water to meet the standard requirements. Objectively speaking, compared with chemical demulsification, thermochemical demulsification and other oil-water emulsion treatment methods, electric field demulsification has received great attention from domestic and foreign researchers in recent years due to its high treatment efficiency and no side effects. The electric field used by most of the three-phase separators in service is still the industrial frequency / high voltage AC electric field, and a large number of engineering operation results to date have shown that the industrial frequency electric dehydration equipment is prone to electrical breakdown, resulting in the destruction of the electric field and electrodes, and problems such as difficulty in powering on. At present, the conventional high-frequency pulse electric field equipment treats shale oil, and the residence time is more than twice that of conventional crude oil treatment. Therefore, there is an urgent need to improve the effectiveness of the electric field used in shale oil electric field separators.

[0008] In view of this, the present invention is proposed. Summary of the invention

[0009] The purpose of the present invention is to provide a two-stage double-gradient three-electric field enhanced demulsification three-phase separator and method to solve the above technical problems existing in the prior art.

[0010] The objective of the present invention is achieved through the following technical solutions:

[0011] The two-stage double-gradient three-electric field enhanced demulsification three-phase separator and method of the present invention comprises a separator tank body, the separator tank body is connected with a crude oil pipeline 5, a water injection pipeline 6, a drug addition pipeline 7, an oil outlet pipeline 20, an air outlet pipeline 24, and a drainage pipeline 22, and the side branch of the drainage pipeline 22 is connected to the separator tank body through a water pump and a mud and sand flushing water pipeline 23;

[0012] The separator tank is provided with a tubular distributor 11 connected to the crude oil pipeline. The direction from the tubular distributor 11 to the oil outlet pipeline 20 is divided into one section and two sections in sequence. Each section is provided with a crude oil processing area. The one section and the two sections are connected by a pipeline located outside the tank between flange 1 27 and flange 28.

[0013] Alternatively, a crude oil gathering section is provided after the second section;

[0014] The first section is composed of gas phase layer 1, oil-rich layer 2, emulsion layer 3, and water-rich layer 4 from top to bottom;

[0015] The second section is oil-rich layer 2 and water-rich layer 4 from top to bottom;

[0016] The crude oil collecting section comprises a gas phase layer 1 and an oil-rich layer 2 from top to bottom.

[0017] The above-mentioned method for realizing crude oil separation and processing by the two-stage double-gradient three-electric-field enhanced demulsification three-phase separator comprises the following steps:

[0018] A. The crude oil mixture enters from the inlet of the tubular distributor outside the tank, and is processed by the tubular distributor to perform preliminary oil and gas separation and change the direction and speed of the fluid. The liquid phase is distributed to the ultra-high frequency / low voltage electric field below the liquid surface;

[0019] B. During the working process of the separator, a double-gradient electric field is a high-frequency / high-voltage pulse electric field in the oil-rich layer and the emulsion layer and an ultra-high-frequency / low-voltage electric field in the liquid phase layer, which respectively provide appropriate electric field parameters for electric field demulsification of crude oil and dehydration treatment;

[0020] C. During the operation of the separator, a section of crude oil with high water content that has not been fully demulsified and dehydrated flows from the pipeline between flange 1 27 and flange 2 28 outside the tank to section 2. Flange 1 27 is located in the crude oil collection section, and then undergoes electric field demulsification and electrostatic agglomeration dehydration through a high-frequency / high-voltage bipolar electric field to further reduce the water content in the crude oil.

[0021] Compared with the prior art, the two-stage double-gradient three-electric-field enhanced demulsification three-phase separator and method provided by the present invention simplifies the existing thermochemical treatment process of crude oil. The three electric fields can effectively perform electric field demulsification and electrostatic agglomeration dehydration on crude oil with corresponding water content in the tank, and can strengthen the chemical demulsification process in the electric field, shortening the residence time of conventional high-frequency pulse electric field treatment of crude oil, and realizing closed, efficient and low-cost treatment of crude oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the structure of a two-stage double-gradient three-electric-field enhanced demulsification three-phase separator provided in Example 1 of the present invention (excluding the crude oil collection section);

[0023] Figure 2 A schematic diagram of the structure of a two-stage double-gradient three-electric-field enhanced demulsification three-phase separator provided in Example 2 of the present invention;

[0024] Figure 3 a. Figure 3 b. Figure 3 C are schematic diagrams of the front view, top view and side view of the integrated mounting electrode provided in an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the structure of a simple electrode plate provided in an embodiment of the present invention;

[0026] The symbols in the figure represent the following:

[0027] 1-gas phase layer, 2-oil-rich layer, 3-emulsion layer, 4-water-rich layer, 5-crude oil pipeline, 6-water injection pipeline, 7-dosing pipeline, 8-heat exchanger, 9-static mixer, 10-mixing valve, 11-tubular distributor, 12-ultra-high frequency / low voltage bare electrode, 13-ground electrode (matching with ultra-high frequency / low voltage bare electrode), 14-high frequency / high voltage insulated electrode, 15-ground electrode (matching with high frequency / high voltage insulated electrode), 16-high frequency / high voltage bipolar bare electrode, 17-ground electrode (matching with high frequency / high voltage bipolar bare electrode), 18-power supply control cabinet, 19-transformer (matching with separator), 20-oil outlet pipeline, 21-sediment flushing pipeline, 22-drainage pipeline, 23-sediment flushing water pipeline, 24-gas outlet pipeline, 25-weir plate 1, 26-weir plate 2, 27 flange 1, 28-flange 2;

[0028] 31-screw, 32-plate, 33-terminal, 34-insulating ceramic ring, 35-nut;

[0029] 41- angle steel, 42- pole plate, 43- angle code. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0031] First, the terms that may be used in this article are explained as follows:

[0032] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0033] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0034] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0035] The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in the field. If no specific conditions are specified in the examples of the present invention, the conditions are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used in the examples of the present invention, they are all conventional products that can be purchased commercially.

[0036] The two-stage double-gradient three-electric field enhanced demulsification three-phase separator and method of the present invention comprises a separator tank body, the separator tank body is connected with a crude oil pipeline 5, a water injection pipeline 6, a drug addition pipeline 7, an oil outlet pipeline 20, an air outlet pipeline 24, and a drainage pipeline 22, and the side branch of the drainage pipeline 22 is connected to the separator tank body through a water pump and a mud and sand flushing water pipeline 23;

[0037] The separator tank is provided with a tubular distributor 11 connected to the crude oil pipeline. The direction from the tubular distributor 11 to the oil outlet pipeline 20 is divided into one section and two sections in sequence. Each section is provided with a crude oil processing area. The one section and the two sections are connected by a pipeline located outside the tank between flange 1 27 and flange 28.

[0038] Alternatively, a crude oil gathering section is provided after the second section;

[0039] The first section is composed of gas phase layer 1, oil-rich layer 2, emulsion layer 3, and water-rich layer 4 from top to bottom;

[0040] The second section is oil-rich layer 2 and water-rich layer 4 from top to bottom;

[0041] The crude oil collecting section comprises a gas phase layer 1 and an oil-rich layer 2 from top to bottom.

[0042] The separator tank is provided with a weir plate 1 25 and a weir plate 26, the first section is arranged between the tubular distributor 11 and the weir plate 1 25, the second section is arranged in the area between the weir plate 26 and the oil outlet, and the crude oil collecting section is arranged in the oil-rich layer 2 between the weir plate 1 25 and the weir plate 26.

[0043] The separator tank body is provided with an electric field power supply device for supporting use, and the electric field power supply device includes a power control cabinet 18 and a transformer 19;

[0044] The separator tank is provided with a high-frequency / high-voltage insulated electrode 14, an ultra-high-frequency / low-voltage bare electrode 12, and a high-frequency / high-voltage bipolar bare electrode 16; or, a heating device is also provided;

[0045] The high-frequency / high-voltage insulated electrode 14 is located in the middle of the first section; the ultra-high-frequency / low-voltage bare electrode 12 is located in the liquid phase layer of the first section, and covers the entire liquid phase layer of the first section when the installation conditions are met; the high-frequency / high-voltage bipolar bare electrode 16 is located in the oil-rich layer of the second section;

[0046] The UHF / LV bare electrodes 12 in the separator tank are installed in an integrated manner, and the pole plates are longitudinal inclined plates with inclined plate sedimentation effect. Several pairs of electrodes are integrated as a whole, and mounting brackets of the electrodes are arranged at corresponding positions in the tank; the electrodes of the same polarity are connected by cables, the UHF / LV bare electrodes 12 are connected to the UHF LV port of the transformer 19, and the grounding electrode 17 is connected to the ground wire, and insulating materials are arranged between the pole plates of different polarities;

[0047] The ultra-high frequency / low voltage bare electrode 12 in the separator tank is also easy to install. The four corners of each electrode plate in one group are connected by four angle steels, and the electrode plates and the angle steels are fixed by angle codes. A mounting bracket for the electrode is arranged at a corresponding position in the tank. Two angle steels on one side of a group of electrodes are connected to the ultra-high frequency / low voltage transformer, and two angle steels on the other side are grounded. In this method, the electrode plates are spliced ​​by metal electrodes and insulating materials of appropriate size, so that the insulating side of the grounded electrode plate is directly fixed to the angle steel on the power-connected side, and the insulating side of the electrode plate is directly fixed to the angle steel on the grounded side.

[0048] The above-mentioned method for realizing crude oil separation and processing by the two-stage double-gradient three-electric-field enhanced demulsification three-phase separator comprises the following steps:

[0049] A. The crude oil mixture enters from the inlet of the tubular distributor outside the tank, and is processed by the tubular distributor to perform preliminary oil and gas separation and change the direction and speed of the fluid. The liquid phase is distributed to the ultra-high frequency / low voltage electric field below the liquid surface;

[0050] B. During the working process of the separator, a double-gradient electric field is a high-frequency / high-voltage pulse electric field in the oil-rich layer and the emulsion layer and an ultra-high-frequency / low-voltage electric field in the liquid phase layer, which respectively provide appropriate electric field parameters for electric field demulsification of crude oil and dehydration treatment;

[0051] C. During the operation of the separator, a section of crude oil with high water content that has not been fully demulsified and dehydrated flows from the pipeline between flange 1 27 and flange 2 28 outside the tank to section 2. Flange 1 27 is located in the crude oil collection section, and then undergoes electric field demulsification and electrostatic agglomeration dehydration through a high-frequency / high-voltage bipolar electric field to further reduce the water content in the crude oil.

[0052] In the step A, the crude oil mixture to be processed enters the tubular distributor from the crude oil pipeline. Since there are many small holes on the side of the vertical tubular distributor, after the mixed crude oil enters the distributor, the gas overflows into the gas phase layer in the tank through the small holes. Due to the effect of gravity, the liquid phase is led to the ultra-high frequency / low voltage electric field in the liquid phase of a section in the tank;

[0053] In the step B, the liquid phase after the preliminary separation of oil and gas in the first section is separated into oil and water layers by relying on the oil-water density difference, the bottom is the separated water-rich layer, the upper part is the oil-rich layer and the emulsion layer containing dispersed water droplets, so a double gradient electric field is provided in the first section; an ultra-high frequency / low voltage electric field is provided in the liquid phase layer of the first section, through which electric field can effectively carry out electric field demulsification treatment and electrostatic aggregation dehydration of crude oil with high water content, and no electric field collapse is achieved; a high frequency / high voltage electric field is provided in the oil-rich layer and the emulsion layer in the middle of the first section, through which electric field can carry out electric field demulsification treatment and electrostatic aggregation dehydration of oil-rich layers and emulsion layers with low water content.

[0054] In the step C, after the crude oil treated by the tubular distributor comes out from its outlet, it first passes through an ultra-high frequency / low voltage electric field for preliminary electrostatic aggregation and dehydration, and the high-water-content crude oil is distributed downward, and the low-water-content crude oil continues to pass through a high-frequency / high-voltage insulating electric field in the middle of the upper part of the liquid phase, and the high-water-content crude oil is subjected to targeted demulsification and dehydration treatment. Thereafter, the crude oil treated by the previous electric field passes through a high-frequency / high-voltage bipolar electric field again, and the crude oil is continuously dehydrated.

[0055] In summary, the two-stage double-gradient three-electric field enhanced demulsification three-phase separator and method of the embodiment of the present invention, in view of the difficult problem of crude oil demulsification and separation treatment, fully utilizes the volume space of the separator, sets two-stage double-gradient three-electric field, and combines demulsifier to strengthen the chemical demulsification effect of crude oil, improves the oil-water separation efficiency, and fully shortens the treatment time. The existing thermochemical treatment process of crude oil is simplified. The three electric fields can effectively perform electric field demulsification and electrostatic agglomeration dehydration on the crude oil with corresponding water content in the tank, and can strengthen the chemical demulsification process in the electric field, shortening the residence time of conventional high-frequency pulse electric field treatment of crude oil, and can realize closed, efficient and low-cost treatment of crude oil.

[0056] The two-stage double-gradient three-electric field enhanced demulsification three-phase separator and method provided in the embodiment of the present invention, on the one hand, use high-frequency / high-voltage electric field, ultra-high-frequency / low-voltage electric field and high-frequency / high-voltage bipolar electric field to replace the conventional industrial frequency / high-voltage AC power supply system to perform electric field demulsification and enhance chemical demulsification, thereby improving the monomer processing efficiency of the separator; on the other hand, ultra-high-frequency / low-voltage electric field is used to replace the conventional high-frequency / high-voltage electric field to treat high-water-content crude oil emulsions, which can achieve effective dehydration of high-water-content emulsions without collapsing the electric field; three electric fields are used to treat crude oil emulsions with different water contents instead of the conventional single high-frequency / high-voltage electric field unified treatment method, so that the crude oil emulsions are fully treated, and the water content of the treated crude oil production liquid is further reduced, thereby ensuring that the quality of the exported crude oil meets the standards and reducing the oil concentration of the water cut, and at the same time, the reagent cost and heating cost can be greatly reduced.

[0057] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the embodiments of the present invention are described in detail with specific embodiments below.

[0058] The main equipment involved in the present invention includes a separator tank, a tubular distributor, a crude oil pipeline, a dosing pipeline, an oil outlet pipeline, an air outlet pipeline, an electric field power supply device, and a heating device (optional). The crude oil produced liquid to be treated, the dilution water (optional), and the demulsifier are heated by the heat exchanger and fully mixed under the action of the static mixer and the mixing valve, and then enter the inlet of the tubular distributor in the separator. The dilution water (optional) extracts the salt in the crude oil during the mixing process. The oil-water mixture enters through the inlet of the tubular distributor outside the tank body, and is sprayed from the vertical pipe inside the tank body toward the outlet hole on one side of the adjacent head, and then collides with the head. In this process, the oil and gas are initially separated and the direction and speed of the fluid are changed. Then the liquid phase is led to a section below the liquid surface, and the oil and water are separated by the difference in oil-water density. The bottom is the separated water-rich layer, and the upper part is the oil-rich layer and the emulsion layer containing dispersed water droplets. Since shale oil has the characteristics of high freezing point, high wax content, high wax precipitation point, small droplet size in emulsion, high emulsification degree, and shale oil and dilution water (optional) are easily emulsified under mixed shearing, part of the emulsion cannot be fully demulsified within the limited hydraulic retention time of the separator, and then an oil-water emulsion layer is formed between the upper oil zone and the lower water zone; and a single electric field cannot effectively treat the emulsion in shale oil, and the water layer will also contain some emulsion, so an ultra-high frequency / low voltage electrode is set in the liquid phase layer of the first stage to effectively treat the high water emulsion in the water-rich layer of the first stage, and a high frequency / high voltage bipolar bare electrode is set in the oil-rich layer of the second stage to effectively treat the low water emulsion in the oil-rich layer of the first stage. Through the above process, the emulsion in the separator can be effectively treated.

[0059] In order to improve the processing efficiency of the separator, the present invention also adopts the electric field to enhance the chemical demulsification effect of the demulsifier, that is, the demulsifier is added to the inlet crude oil and the dilution water (optional) while being mixed, and the temperature is increased by passing through a heat exchanger before entering the external inlet of the tubular distributor, so that the electric field and the demulsifier can achieve a higher demulsification efficiency under the coupling synergistic effect of a certain temperature.

[0060] The two-stage double-gradient three-electric field enhanced demulsification three-phase separator and method of the present invention, on the one hand, use high-frequency / high-voltage electric field, ultra-high-frequency / low-voltage electric field and high-frequency / high-voltage bipolar electric field to replace the conventional single power frequency / high-voltage AC power supply system, strengthen the electric field effect, and improve the monomer processing efficiency of the separator; on the other hand, ultra-high-frequency / low-voltage electric field is used to replace the conventional high-frequency / high-voltage electric field to treat high-water crude oil emulsions, and the required field strength is lower, and the electric field can be stabilized without collapse, and stable dehydration can be achieved; three electric fields are used to treat shale oil emulsions in a segmented and targeted manner instead of the conventional single high-frequency / high-voltage electric field to treat crude oil, so that the water content of the treated shale oil is further reduced. This process can effectively remove the high-water emulsion and low-water emulsion dispersed in the tank caused by the conventional three-phase separation process, make full use of the separator volume space, set two-stage double-gradient three-electric field, strengthen the chemical demulsification effect of the shale oil demulsifier, improve the oil-water separation efficiency, and fully shorten the processing time.

[0061] Example 1

[0062] like Figure 1 , Figure 2 and Figure 3 a. Figure 3 b. Figure 3As shown in c, the crude oil to be treated in the crude oil pipeline 5 and the dilution water (optional) in the water injection pipeline 6 are mixed through the static mixer 9 and the mixing valve 10. At the same time, in order to ensure that the separator has a relatively good demulsification effect, an appropriate amount of demulsifier is added to the mixed liquid through the reagent pipeline 7, and then the mixed liquid is appropriately heated through the heat exchange device 8. The mixed liquid enters through the inlet of the tubular distributor 11 outside the tank body, and is sprayed out from the vertical pipe inside the tank body toward the outlet hole on the side of the adjacent head, and then collides with the head. In this process, the oil and gas are initially separated and the direction and speed of the fluid are changed. The gas floats to the top of the tank to form a gas phase layer 1, and then the liquid phase is led below the liquid surface. The oil and water are separated by the difference in oil and water density. The bottom is the separated water-rich layer 4, and the upper part is the oil-rich layer 2 and the emulsion layer 3 containing dispersed water droplets. An ultra-high frequency / low voltage electric field is provided in a liquid phase layer, and this electric field can effectively enhance the high-content Chemical demulsification and dehydration of water-crude oil, and can achieve no electric field collapse; a high-frequency / high-voltage electric field is provided in a section of the oil-rich layer and the emulsion layer, and the chemical demulsification and dehydration of the oil-rich layer and the emulsion layer with low water content can be strengthened by the electric field; in order to prevent the adjacent poles of the high-frequency / high-voltage electrode from short-circuiting and breaking down under the action of strong voltage, the high-voltage pole 14 can be insulated, that is, a layer of insulating material is coated on the high-voltage electrode 14, and the insulating material can be selected from polytetrafluoroethylene (PTFE), polyperfluoroethylene propylene (FEP), fluororubber, ceramics, etc. The crude oil containing low-water emulsion after the first stage of treatment flows along the tank external pipeline between flange 1 27 and flange 2 28, and the liquid flows to the oil-rich layer of the second section, and the low-water emulsion is further demulsified in the electric field area formed between the separator high-frequency / high-voltage bipolar bare electrode 16 and the grounded bare electrode 17. After the above treatment, the oil in the crude oil collection section (optional) of the tank is transported out through the external transmission pipeline 20, and the water at the bottom is transported to the sewage treatment process through the pipeline 22, of which part of the water is circulated to the sand flushing water pipeline 23 as a sand flushing water source, and the sand flushing manifold 21 is used to blow away the sediment at the bottom of the separator tank.

[0063] In order to further improve the processing efficiency, the crude oil produced liquid is heated to a certain extent by a heating device or a heat exchanger before entering the separator tubular distributor, and at the same time, an appropriate amount of demulsifier is added to the incoming liquid through the reagent pipeline.

[0064] Compared with other process improvement solutions in the field, the present invention has the following advantages:

[0065] 1. Compared with the treatment methods such as centrifugal method, chemical demulsification method and flash evaporation method, the electric field demulsification requires fewer treatment units and has higher treatment efficiency. It does not require large-scale temperature increase and large amounts of chemical agents, which can significantly save treatment costs and ensure the smooth and efficient operation of the separator on the basis of improving treatment efficiency.

[0066] 2. Use high-frequency / high-voltage electric field, ultra-high-frequency / low-voltage electric field and high-frequency / high-voltage bipolar electric field to replace conventional power frequency / high-voltage AC electric field. The electric field strengthens the effect of chemical agents and improves the monomer processing efficiency of the separator;

[0067] 3. Use ultra-high frequency / low voltage electric field instead of conventional high frequency / high voltage electric field to effectively treat high water content crude oil emulsion, which can achieve stable dehydration without electric field collapse;

[0068] 4. Two-stage double-gradient three-electric field is used to replace the conventional single high-frequency / high-voltage electric field to treat crude oil emulsion, and crude oil and emulsions with various water contents in the separator are treated in a targeted manner, so that the water content of the treated crude oil production liquid is further reduced. The two-stage three-electric field treatment process ensures that the quality of exported crude oil meets the standards, and can also further reduce the cost of reagents and heating costs.

[0069] The above is only a 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 any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section 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 in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A two-stage double-gradient three-electric field enhanced demulsification three-phase separator and method, characterized in that: The separator tank body comprises a crude oil pipeline (5), a water injection pipeline (6), a drug addition pipeline (7), an oil outlet pipeline (20), an air outlet pipeline (24), and a drainage pipeline (22), wherein a side branch of the drainage pipeline (22) is connected to the separator tank body via a water pump and a mud and sand flushing water pipeline (23); The separator tank is provided with a tubular distributor (11) connected to the crude oil pipeline. The direction from the tubular distributor (11) to the oil outlet pipeline (20) is divided into one section and two sections in sequence. Each section is provided with a crude oil processing area. The first section and the second section are connected by a pipeline located outside the tank between flange 1 (27) and flange 2 (28); Alternatively, a crude oil gathering section is provided after the second section; The first section comprises, from top to bottom, a gas phase layer (1), an oil-rich layer (2), an emulsion layer (3), and a water-rich layer (4); The two sections are, from top to bottom, an oil-rich layer (2) and a water-rich layer (4); The crude oil collecting section comprises a gas phase layer (1) and an oil-rich layer (2) from top to bottom.

2. The two-stage double-gradient three-electric-field enhanced demulsification three-phase separator according to claim 1 is characterized in that: The separator tank is provided with a weir plate 1 (25) and a weir plate 2 (26), the first section is provided between the tubular distributor (11) and the weir plate 1 (25), the second section is provided in the area between the weir plate 2 (26) and the oil outlet, and the crude oil collecting section is provided in the oil-rich layer (2) between the weir plate 1 (25) and the weir plate 2 (26).

3. The two-stage double-gradient three-electric-field enhanced demulsification three-phase separator according to claim 2 is characterized in that: The separator tank is provided with an electric field power supply device for matching use, and the electric field power supply device includes a power control cabinet (18) and a transformer (19); The separator tank is provided with a high-frequency / high-voltage insulated electrode (14), an ultra-high-frequency / low-voltage bare electrode (12), and a high-frequency / high-voltage bipolar bare electrode (16); or, a heating device is also provided; The high-frequency / high-voltage insulated electrode (14) is located in the middle of the first section; the ultra-high-frequency / low-voltage bare electrode (12) is located in the liquid phase layer of the first section, and covers the entire liquid phase layer of the first section when the installation conditions are met; the high-frequency / high-voltage bipolar bare electrode (16) is located in the oil-rich layer of the second section; The ultra-high frequency / low voltage bare electrodes (12) in the separator tank are installed in an integrated manner, and the pole plates are longitudinal inclined plates with inclined plate sedimentation effect. Several pairs of electrodes are integrated as a whole, and mounting brackets for the electrodes are arranged at corresponding positions in the tank; electrodes of the same polarity are connected by cables, the ultra-high frequency / low voltage bare electrodes (12) are connected to the ultra-high frequency low voltage port of the transformer (19), and the grounding electrode (17) is connected to the ground wire, and insulating materials are arranged between pole plates of different polarities; The ultra-high frequency / low voltage bare electrode (12) in the separator tank is also easy to install, wherein the four corners of each electrode plate in one group are connected by four angle steels, and the electrode plates and the angle steels are fixed by angle codes. A mounting bracket for the electrode is provided at a corresponding position in the tank, wherein two angle steels on one side of a group of electrodes are connected to the ultra-high frequency / low voltage transformer, and two angle steels on the other side are grounded. In this method, the electrode plates are spliced ​​by metal electrodes and insulating materials of appropriate size, so that the insulating side of the grounded electrode plate is directly fixed to the angle steel on the power-connected side, and the insulating side of the electrode plate is directly fixed to the angle steel on the grounded side.

4. A method for separating crude oil using a two-stage double-gradient three-electric-field enhanced demulsification three-phase separator according to any one of claims 1 to 3, characterized in that: Includes steps: A. The crude oil mixture enters from the inlet of the tubular distributor outside the tank, and is processed by the tubular distributor to perform preliminary oil and gas separation and change the direction and speed of the fluid. The liquid phase is distributed to the ultra-high frequency / low voltage electric field below the liquid surface; B. During the working process of the separator, a double-gradient electric field is a high-frequency / high-voltage pulse electric field in the oil-rich layer and the emulsion layer and an ultra-high-frequency / low-voltage electric field in the liquid phase layer, which respectively provide appropriate electric field parameters for electric field demulsification of crude oil and dehydration treatment; C. During the operation of the separator, a section of crude oil with high water content that has not been fully demulsified and dehydrated flows from the pipeline between flange 1 (27) and flange 2 (28) outside the tank to section 2. Flange 1 (27) is located in the crude oil collection section, and then undergoes electric field demulsification and electrostatic agglomeration dehydration through a high-frequency / high-voltage bipolar electric field to further reduce the water content in the crude oil.

5. The method for realizing crude oil separation and treatment by using a two-stage double-gradient three-electric-field enhanced demulsification three-phase separator according to claim 4, characterized in that: In the step A, the crude oil mixture to be processed enters the tubular distributor from the crude oil pipeline. Since there are many small holes on the side of the vertical tubular distributor, after the mixed crude oil enters the distributor, the gas overflows into the gas phase layer in the tank through the small holes. Due to the effect of gravity, the liquid phase is led to the ultra-high frequency / low voltage electric field in the liquid phase of a section in the tank; In the step B, the liquid phase after the preliminary separation of oil and gas in the first stage is separated into oil and water layers by the density difference between oil and water, the bottom is the separated water-rich layer, the upper part is the oil-rich layer and the emulsion layer containing dispersed water droplets, so a double gradient electric field is provided in the first stage; An ultra-high frequency / low voltage electric field is set in a liquid phase layer, through which electric field demulsification and electrostatic aggregation dehydration of crude oil with high water content can be effectively carried out without electric field collapse; A high frequency / high voltage electric field is provided in the oil-rich layer and the emulsion layer in the middle of a section, through which the electric field can be used for electric field demulsification treatment and electrostatic coalescence dehydration of the oil-rich layer and the emulsion layer with low water content.

6. The method for realizing crude oil separation and processing by using a two-stage double-gradient three-electric-field enhanced demulsification three-phase separator according to claim 5, characterized in that: In the step C, after the crude oil treated by the tubular distributor comes out from its outlet, it first passes through an ultra-high frequency / low voltage electric field for preliminary electrostatic aggregation and dehydration, and the high-water-content crude oil is distributed downward, and the low-water-content crude oil continues to pass through a high-frequency / high-voltage insulating electric field in the middle of the upper part of the liquid phase, and the high-water-content crude oil is subjected to targeted demulsification and dehydration treatment. Thereafter, the crude oil treated by the previous electric field passes through a high-frequency / high-voltage bipolar electric field again, and the crude oil is continuously dehydrated.

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