Gas pre-separation-water pre-separation high-frequency electric coalescence oil-water separation device as well as separation method and application thereof
By using a pre-gas-pre-water high-frequency electro-coalescing oil-water separation device, which combines gravity and electrostatic coalescence technologies, the problems of large footprint and low efficiency of oil-water separation equipment in oil fields have been solved. This device achieves efficient and continuous oil-water separation, and is suitable for both offshore and onshore oil fields.
Patent Information
- Application Number
- CN202511068578.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-31
- Publication Date
- 2025-10-31
AI Technical Summary
Existing oilfield oil-water separation equipment has a large footprint, low dehydration efficiency, and high energy consumption. It is also difficult to effectively process crude oil emulsions with high water content. Especially in the case of limited space on offshore platforms, conventional electro-dehydration processes have poor adaptability and are prone to "electric field collapse".
A pre-gas-pre-water high-frequency electro-coalescing oil-water separation device is adopted, which includes a vertically arranged gas-liquid separation tank and separation pipe. Combined with high-voltage AC insulated electrodes and a high-frequency power supply, oil-water separation is achieved through a combination of gravity separation and electrostatic coalescence.
It enables continuous and integrated processing of crude oil, with small size, short process, and high efficiency. It can effectively process crude oil with high water content, avoid electric field breakdown, and is suitable for both offshore and onshore oil fields.
Smart Images
Figure CN120867704A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of oilfield multiphase separation technology, specifically relating to a pre-gas-pre-water high-frequency electro-coalescing oil-water separation device and its separation method. Background Technology
[0002] As oilfields enter the later stages of extraction, water injection becomes the mainstream method, leading to a water content in the extracted crude oil that is generally around 90%. High water content crude oil brings numerous problems, such as increased fuel consumption in heating systems, increased transportation energy consumption due to excessive viscosity, corrosion and damage to oilfield metal pipelines and equipment, and negative impacts on the refining process. Therefore, crude oil dehydration is crucial for reducing economic losses, mitigating safety risks, and improving production efficiency.
[0003] In crude oil dehydration methods, gravity sedimentation or centrifugal separation are commonly used to remove free water and larger water droplets. However, for stable emulsions (especially small droplets), these methods are less efficient or require very long residence times or extremely high centrifugal forces. Electrostatic demulsification is often used for emulsions, promoting droplet coalescence in a high-voltage electric field, causing tiny droplets to merge into sufficiently large droplets that can be effectively removed by subsequent separation methods. Currently, oilfields generally use a "three-stage three-phase gravity separator + electrostatic dehydrator (salt collector)" for crude oil dehydration, but this equipment has a large footprint, low dehydration efficiency, and high energy consumption. Furthermore, with the increasing number of offshore oil extraction projects, the limited space on production platforms places even greater demands on the size and weight of dehydration equipment.
[0004] Furthermore, the high water content of the produced fluid at the oilfield site results in a persistently high water content in the crude oil entering the electrostatic dehydrator after initial separation in the three-phase separator. Conventional electrostatic dehydration processes are suitable for dehydrating low-water-content crude oil (below 30%), but their dehydration effect is poor, and the separated water is turbid. Simultaneously, ordinary power frequency power supplies and uninsulated high-voltage electrodes are poorly adapted to high-water-content crude oil emulsions, easily leading to phenomena such as "electric field collapse," which causes the dehydration equipment to malfunction and operate unstablely. Summary of the Invention
[0005] The purpose of this invention is to provide a high-frequency electro-coalescing oil-water separation device for pre-gas separation and pre-water separation, as well as its separation method and application, thereby overcoming the shortcomings of the prior art. It is applicable to the oil-water separation process of produced fluids in offshore and onshore oilfields, realizing continuous and integrated processing of crude oil. It has the characteristics of small size, short process, high efficiency, compact structure, and low puncture resistance.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a pre-gas-pre-water high-frequency electro-coalescence oil-water separation device, comprising a vertically arranged gas-liquid separation tank and a separation pipe, wherein a pre-gas separation section is provided inside the gas-liquid separation tank, and a liquid phase outlet pipe is provided on the side wall of the gas-liquid separation tank, and a certain distance is provided between the liquid phase outlet pipe and the top of the gas-liquid separation tank. The gas-liquid separator is connected to the separation pipe via a liquid phase outlet pipe. The separator is equipped with a high-voltage AC insulated electrode. The high-voltage AC insulated electrode is equipped with a high-voltage electrode insulated cover plate at both the upper and lower ends. The high-voltage electrode insulated cover plate divides the separator into three sections: the upper section is the purified oil outlet section, the middle section is the electrostatic coalescence section, and the lower section is the pre-water separation section. The electrostatic coalescence section is located above the liquid phase outlet pipe of the gas-liquid separator.
[0007] Crude oil-containing produced fluids are typically under high pressure in underground oil reservoirs, dissolving large amounts of natural gas (mainly methane, ethane, propane, etc.). When the produced fluid is brought to the surface, the pressure drops sharply, causing these dissolved gases to be released rapidly and expand dramatically in volume. If not separated in time, these high-pressure gases pose a significant explosion risk in sealed pipes or containers. This invention employs a vertically positioned gas-liquid separator to separate the gas and liquid in the produced fluid. The gas is discharged through a pre-separation section exhaust pipe at the top of the separator, while the degassed produced fluid enters the separation pipe for further separation through a liquid phase outlet pipe on the side wall of the separator. Simultaneously, a certain gap is maintained between the liquid phase outlet pipe and the top of the separator to provide space for gas separation, thereby improving the gas-liquid separation efficiency.
[0008] After degassing, the produced fluid enters the separation tube through the liquid phase outlet pipe of the gas-liquid separator. Under the influence of gravity and due to the density difference between oil and water, the degassed produced fluid automatically separates into three phases from top to bottom in the separation tube: an oil phase, an emulsion, and an aqueous phase. The aqueous phase exits through the lower pre-separation section, the oil phase exits through the upper purified oil outlet section, and the emulsion enters the electrostatic coalescence section where it undergoes separation and coalescence under the influence of an electric field. Small water droplets in the emulsion coalesce into larger droplets under the action of a radially unevenly distributed electric field, and exit from the pre-separation section. The oil in the emulsion, after electrostatic coalescence, exits through the upper purified oil outlet section. The electrostatic coalescence section is located at the upper part of the liquid phase outlet pipe of the gas-liquid separator, which facilitates better electrostatic coalescence of the emulsion and improves the separation efficiency of water and oil in the emulsion.
[0009] Furthermore, given the typically limited energy supply and space on offshore platforms, this invention employs a vertically mounted pre-gas-pre-water high-frequency electro-coalescence oil-water separation device, which is more suitable for the unique environment of offshore platforms and allows for simultaneous operation of multiple pipelines. This device features small size, short process flow, high efficiency, large processing capacity, and resistance to breakdown, enabling continuous and integrated crude oil processing.
[0010] In some other embodiments, there are multiple separation tubes, which are vertically arranged parallel to each other around the gas-liquid separation tank. The multiple gas-liquid separation tanks are connected to the multiple separation tubes through liquid phase outlet pipes. The gas-liquid separator includes a cylindrical vertical tube and a conical tube located at the lower end of the cylindrical vertical tube; The bottom of the gas-liquid separator is equipped with an L-shaped produced liquid inlet pipe, and a sample branch pipe for the produced liquid inlet pipe is provided on the produced liquid inlet pipe.
[0011] By installing multiple separation pipes around the gas-liquid separator, the separation efficiency of the degassed produced fluid can be improved. This type of gas-liquid separator offers higher separation efficiency, stronger resistance to fluctuations, more thorough drainage, lower maintenance costs, and a longer equipment lifespan.
[0012] In some other embodiments, the number of separation tubes is four, and the four separation tubes are arranged vertically and parallel to each other around the gas-liquid separator. The gas-liquid separator is equipped with a handle flange butterfly valve on the liquid phase outlet pipe. The gas-liquid separator and the separation pipe are connected via the liquid phase outlet pipe, which is also equipped with a handle flange butterfly valve. The produced liquid undergoes gas-liquid separation in the pre-gas separation section of the gas-liquid separator. After degassing, the produced liquid enters the separation pipe for further separation through the handle flange butterfly valve on the liquid phase outlet pipe.
[0013] The separation tube comprises a cylindrical vertical tube and a tapered tube located at the lower end of the cylindrical vertical tube, with the bottom of the separation tube connected to an L-shaped tube; the separation tube also comprises a cylindrical straight tube and a tapered tube located at the lower end of the cylindrical straight tube, with the bottom of the separation tube connected to an L-shaped tube. This structure of the separation tube offers higher separation efficiency, stronger resistance to fluctuations, more thorough drainage performance, lower maintenance costs, and a longer equipment lifespan.
[0014] The diameters of the cylindrical vertical pipes and conical pipes in the separation tube are smaller than those in the gas-liquid separator. After the produced fluid enters the pre-water separation section, under the action of gravity, the free water is concentrated in the lower half of the pre-water separation section and then discharged through the oily wastewater outlet pipe, while the crude oil enters the electrostatic coalescence section.
[0015] In some other embodiments, there are two separation tubes, which are vertically arranged parallel to each other on both sides of the gas-liquid separation tank. The gas-liquid separation tank is connected to the two separation tubes through liquid phase outlet pipes. The horizontal pipes in the L-shaped pipes at the bottom of the two separation tubes are connected to the oily wastewater outlet pipes. The oily wastewater outlet pipes are equipped with oily wastewater outlet pipe sampling branch pipes. The oily wastewater outlet pipe is connected to the wastewater treatment system.
[0016] By installing multiple separation pipes around the gas-liquid separator, the separation efficiency of the degassed produced fluid can be improved. This type of gas-liquid separator offers higher separation efficiency, stronger resistance to fluctuations, more thorough drainage, lower maintenance costs, and a longer equipment lifespan.
[0017] In some other embodiments, a purified oil outlet pipe is provided on the side wall of the purified oil outlet section, and a purified oil outlet pipe sampling branch pipe is provided on the purified oil outlet pipe. The electrostatic coalescence section includes a high-voltage AC insulated electrode and a high-voltage power supply, with the high-voltage AC insulated electrode connected to the high-voltage power supply.
[0018] After crude oil enters the electrostatic coalescence section, the high-voltage AC electrode at the center of the coalescer is energized. Small droplets are agglomerated into larger droplets due to the radially distributed non-uniform electric field. Under gravity, these larger droplets settle and are discharged from the lower oily wastewater outlet pipe along with the pre-separated water. The electrostatically coalesced crude oil is then discharged from the upper purified oil outlet pipe through the coalescer wiring section. The high-voltage electrode insulating cover is bolted to the electrostatic coalescence section. The pre-separation water section is flanged to the electrostatic coalescence section.
[0019] In some other embodiments, the length of the electrostatic coalescer does not exceed 10,000 mm.
[0020] In a second aspect, the present invention provides a pre-gas-pre-water electro-polymerization oil-water separation method, employing the pre-gas-pre-water high-frequency electro-polymerization oil-water separation device of the first aspect, comprising the following steps: The produced fluid enters the gas-liquid separator through the produced fluid inlet pipe for gas-liquid separation to obtain degassed produced fluid; After degassing, the produced fluid enters the separation tube through the liquid phase outlet pipe on the gas-liquid separator, where it is automatically separated to obtain oil phase, free water, and oil-water emulsion; the oil phase and free water are discharged through the purified oil outlet section and the pre-water separation section in the separation tube, respectively. The oil-water emulsion in the produced fluid is separated into oil and water phases under the action of the electric field in the electrostatic coalescence section of the separation tube, and then discharged through the purified oil outlet section and the pre-water separation section of the separation tube, respectively.
[0021] In the separation method of this application, the degassed produced fluid undergoes preliminary oil-water separation in the pre-water separation section within the separation pipe due to the density difference between oil and water. Under the influence of gravity, the denser water phase concentrates in the lower part of the pre-water separation section, while the less dense oil phase concentrates in the upper part. Under the influence of an electric field, the dispersed water particles in the oil-water emulsion become polarized. The positive and negative charges between the polarized water droplets attract and induce each other, causing the droplets to stretch and deform and move relative to each other. During this deformation process, due to the presence of the electric field, the water droplets arrange themselves in a chain-like pattern along the direction of the electric field, forming a "water chain." Adjacent water droplets attract each other with their positive and negative poles, eventually merging into larger droplets under this attraction. These droplets settle and separate from the crude oil, and are discharged along with the pre-separated water from the oily wastewater outlet pipe. The electro-aggregated crude oil is discharged from the upper purified oil outlet section.
[0022] In some other embodiments, the high-voltage power supply input voltage in the electrostatic coalescence section ranges from 6 kV to 15 kV, and the input electric field frequency ranges from 500 Hz to 20 kHz.
[0023] The pulsed electric field generated by the high-frequency pulsed power supply produces a smaller current, which is less likely to cause electrolysis of the aqueous phase. Therefore, applying a high-frequency, high-voltage pulsed electric field is less likely to cause breakdown of the electric field, thereby enhancing the polarization of the droplets. Furthermore, the pulsed electric field can effectively increase the number of droplet oscillations, creating more contact opportunities for the droplets and thus achieving a better droplet coalescence effect.
[0024] In some other embodiments, the sampled fluid is also taken through sampling branch pipes provided on the produced fluid inlet pipe. The purified oil is sampled by installing a sampling branch pipe on the purified oil outlet pipe. A sampling branch pipe is installed on the oily wastewater outlet pipe to sample the oily wastewater.
[0025] The sampling branch pipes at the inlet of produced fluid, the outlet of purified oil, and the outlet of oily wastewater are mainly used to periodically collect samples to determine parameters such as water content (distillation method) and sand content (gravimetric method), to verify whether the dehydration efficiency meets the design requirements. By comparing samples from different nodes, the changes in water content after adjusting the electric field strength and frequency are analyzed to determine the optimal combination of operating parameters.
[0026] Thirdly, the present invention provides the application of the pre-gas-pre-water high-frequency electro-coalescing oil-water separation device of the first aspect in the oil-water separation of produced oil in oilfields, wherein the water content of the produced oil is above 70%, and the water content of the purified oil discharged from the purified oil outlet section is below 20%.
[0027] The beneficial effects of this invention are: (1) The device of the present invention is composed of a gas-liquid separator and multiple separation pipes, which can realize the simultaneous operation of multiple pipes. The device has the characteristics of small size, short process, high efficiency, large processing capacity and not easy to break down, and can realize continuous and integrated processing of crude oil.
[0028] (2) The separation method of the present invention allows crude oil to first enter the pre-water separation section for pre-dehydration, and then the pre-dehydrated crude oil with lower water content enters the electro-coalescing section for efficient droplet coalescence. This achieves the purpose of shortening the processing flow, improving the front-end dehydration effect, reducing the residence time in the settling tank, increasing the dehydration rate, and reducing energy consumption.
[0029] In summary, this invention employs a "pre-gas separation + pre-water separation + high-frequency electrostatic coalescence" process. It is powered by a high-frequency power supply and uses high-voltage electrodes with insulation protection to avoid the "field collapse" phenomenon, effectively improving oil-water separation efficiency and reducing the residence time in the settling tank. The purified crude oil after treatment can meet the qualified indicators for transportation and is suitable for high water content land and offshore platforms. Attached Figure Description
[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0031] Figure 1 This is a schematic diagram of the overall structure of the pre-gas separation-pre-water separation high-frequency electro-coalescence oil-water separation device in Embodiment 1 of the present invention; Figure 2 This is a top view of the pre-gas-pre-water high-frequency electro-polymerization oil-water separation device in Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the pipeline-type electrostatic coalescence section structure in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the high-voltage insulating cover plate structure of the pipeline electrostatic coalescer in Embodiment 1 of the present invention; The components include: 1. Produced fluid inlet pipe; 2. Produced fluid inlet pipe sampling branch pipe; 3. Gas-liquid separator; 4. Pre-gas separation section; 5. Pre-gas separation section exhaust pipe; 6. Handle flange butterfly valve; 7. Pre-water separation section; 8. High-voltage electrode insulating cover plate; 9. Electrostatic coalescence section; 10. High-voltage AC insulating electrode; 11. Purified oil outlet pipe; 12. High-voltage power supply; 13. Purified oil outlet pipe sampling branch pipe; 14. Purified oil outlet section; 15. Oily wastewater outlet pipe; 16. Oily wastewater outlet pipe sampling branch pipe; and 17. Flange. Detailed Implementation
[0032] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Specific conditions not specified in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Components whose manufacturers are not specified are all commercially available conventional products.
[0033] The general process for crude oil dehydration is as follows: First, free water is removed from the crude oil through gravity sedimentation, reducing the water content. Then, electrostatic coalescence separation is used to further reduce the water content and improve the purity of the crude oil. Regarding the mechanism of electrostatic coalescence separation, the industry generally believes that parameters such as electric field strength and frequency affect the demulsification effect of W / O emulsions. Ultimately, four electrostatic coalescence mechanisms have been summarized: dipolar coalescence, oscillation coalescence, electrophoretic coalescence, and di-electrophoretic coalescence.
[0034] Dipolar coalescence refers to the polarization of dispersed water particles in crude oil emulsions under a high-voltage electric field. The positive and negative charges of the polarized water droplets attract and induce each other, causing the droplets to stretch and deform and move relative to each other. During this deformation, the presence of the electric field causes the water droplets to arrange themselves in a chain-like pattern along the direction of the electric field, forming a "water chain." Adjacent water droplets attract each other with their positive and negative poles, eventually merging into larger droplets under this attraction and settling out of the crude oil.
[0035] Oscillatory coalescence refers to the phenomenon where water droplets in an alternating electric field oscillate rapidly at excessively high frequencies, resulting in less deformation and preventing breakage even under strong electric fields. As the direction of the electric field constantly changes, the positive and negative ions in the droplets undergo continuous periodic reciprocating motion, causing constant impact and deformation of the interfacial film. This process facilitates coalescence between the droplets.
[0036] Electrophoretic coalescence refers to the movement of water particles along the electric field lines after polarization under the action of a DC electric field. Since the particle size of each dispersed phase droplet is different, the electrophoretic velocity of the droplets under the action of the electric field is different, which in turn causes the droplets to collide and coalesce with each other.
[0037] Dielectrophoretic coalescence refers to the coalescence that occurs when a droplet moves toward a direction with a denser electric field due to the uneven force exerted on the droplet under a non-uniform electric field caused by the difference in charge density inside and outside the droplet.
[0038] The crude oil dehydration process in the electrostatic coalescence section of this invention is based on the electric field polarization effect. Its core mechanism can be described as follows: when water-containing crude oil flows through the non-uniform electric field formed by high-voltage insulating electrodes, the dispersed phase water droplets undergo dipole coalescence under the action of alternating electric field force, and an attractive force is formed between adjacent droplets. (in the formula) The vacuum permittivity, The relative permittivity of crude oil, The ratio of the droplet dielectric constants, For electric field strength, Where is the droplet radius, (where the distance between the droplets is the distance between them), which causes the droplets to align along the electric field lines into a chain-like structure and collide.
[0039] After the pre-separation stage under gravity and the electrostatic coalescence process, the water content of the crude oil has been significantly reduced. Therefore, the crude oil can meet export standards after electrostatic coalescence. The selection of electric field parameters has a significant impact on the electrostatic coalescence parameters. In the electrostatic dehydration process, there is often a critical electric field parameter that optimizes the dehydration effect. These electric field parameters can be specifically expressed as electric field frequency and electric field strength. Electric field strength (… The polarization force directly determines the degree of droplet polarization and the driving force for coalescence. According to the polarization force formula... As the electric field strength increases, the attractive force between droplets increases quadratically, promoting chain aggregation. However, there exists a critical electric field strength. ( (Interfacial tension), exceeding which triggers electrodispersion, causing large water droplets to break down into microdroplets. Frequency ( The frequency of the electric field determines the mode of action. At low frequencies, breakdown is more likely to occur; high-frequency pulsed electric fields shorten the duration of a single pulse, making breakdown less likely, resulting in higher coalescence efficiency and reduced maintenance.
[0040] Besides the influence of electric field parameters, fluid flow regime also affects the coalescence process of emulsion droplets. Moderate turbulence leads to frequent droplet collisions, resulting in better coalescence than static or laminar flow. Excessive turbulence intensity causes large droplets to break up and disperse after coalescence, thus reducing the electrostatic coalescence effect. During demulsification, there is an optimal value for the turbulence intensity generated by the flow field. This optimal value represents the optimal flow state inside the electrostatic coalescer, resulting in the best demulsification effect. Therefore, it is necessary to correctly control the turbulence intensity during the design of the electrostatic coalescer.
[0041] The content of the present invention will be described below through specific embodiments: Example 1 A pre-gas-pre-water high-frequency electro-coalescence oil-water separation device, such as Figure 1 and Figure 2As shown, the system includes a gas-liquid separator 3 and parallel separation pipes on both sides of the separator 3. The gas-liquid separator 3 consists of a cylindrical straight pipe and a tapered pipe at the lower end of the cylindrical straight pipe. The combined structure of "column-section steady flow separation + tapered section liquid collection and drainage" provides higher separation efficiency, stronger resistance to fluctuations, more thorough drainage performance, lower maintenance costs, and longer equipment lifespan. The top of the gas-liquid separator 3 is equipped with a pre-separation section exhaust pipe 5, and a liquid phase outlet pipe is provided on the gas-liquid separator 3 to discharge the exhaust liquid phase. The bottom of the gas-liquid separator 3 is equipped with an L-shaped produced fluid inlet pipe 1, and a sampler branch pipe 2 is provided on the produced fluid inlet pipe 1. The gas-liquid separator 3 is used to separate the gas from the liquid (water and oil-water emulsion) in the produced fluid.
[0042] There are multiple separation tubes. The separation tubes are connected to the gas-liquid separator 3 through the liquid phase outlet pipe. A handle flange butterfly valve 6 is provided on the horizontal branch pipe. The handle flange butterfly valve 6 controls the opening and closing of the gas-liquid separator 3 and the separation tubes, so that the liquid in the gas-liquid separator 3 enters the separation tubes for further separation.
[0043] Taking two separation pipes as an example, the structure of the oil-water separation device is explained in detail. Two separation pipes are arranged parallel to each other on both sides of the gas-liquid separator 3. Each separation pipe includes a cylindrical straight pipe and a tapered pipe located at the lower end of the cylindrical straight pipe. The bottom of the separation pipe connects to an L-shaped straight pipe, and the L-shaped straight pipes at the bottom of the two separation pipes are connected and eventually converge to form an oily wastewater outlet pipe 15. A sampling branch pipe 16 is provided on the oily wastewater outlet pipe 15. The oily wastewater outlet pipe 15 is connected to the wastewater treatment system via a flange 17.
[0044] The separator is equipped with a high-voltage electrode insulating cover plate 8, which divides the separator into three sections. The lower section is the pre-water separation section 7, the middle section is the electrostatic coalescence section 9, and the upper section is the purified oil outlet section 14. The pre-water separation section 7 and the electrostatic coalescence section 9 are connected by a flange.
[0045] like Figure 3 As shown, the electrostatic coalescence section 9 includes a high-voltage AC insulated electrode 10 and a high-voltage power supply 12 connected thereto. The high-voltage AC insulated electrode 10 has high-voltage electrode insulating cover plates 8 on its upper and lower sides, and the high-voltage electrode insulating cover plates 8 are connected to the electrostatic coalescence section 9 by bolts.
[0046] The high-voltage electrode insulating cover 8 includes a top insulating cover and a bottom insulating cover. For example... Figure 4 As shown, the high-voltage electrode insulating cover is an existing flange structure. The outer ring of the high-voltage electrode insulating cover is a standard annular flange face, i.e., eight bolt holes are evenly distributed around the circumference, with the center of the holes located at the midpoint of the flange radius. The inner ring is a functional connecting ring.
[0047] When the high-voltage AC insulating electrode 10 in the electrostatic coalescence section 9 is energized, small droplets will coalesce into larger droplets due to the radially distributed non-uniform electric field. Under the action of gravity, they will settle and be discharged from the lower oily wastewater outlet pipe 15 along with the pre-separated water. The purified oil outlet section 14 is provided with a purified oil outlet pipe 11 on its side wall, and a purified oil outlet pipe sampling branch pipe 13 is provided on the purified oil outlet pipe 11.
[0048] Example 2 like Figure 2 This is a top view of the pre-gas-pre-water high-frequency electro-coalescence oil-water separation device. Unlike Embodiment 1, this device has four separation pipes, arranged parallel to each other around the gas-liquid separator 3. The four separation pipes are connected by L-shaped straight pipes at their bottoms, eventually converging to form an oily wastewater outlet pipe 15. A sampling branch pipe 16 is provided on the oily wastewater outlet pipe 15. The oily wastewater outlet pipe 15 is connected to the wastewater treatment system via a flange 17.
[0049] Example 3 A pre-gas separation-pre-water electro-coalescing oil-water separation method includes the following steps: The produced fluid enters the gas-liquid separator 3 through the produced fluid inlet pipe 1, where gas-liquid separation is achieved in the pre-gas separation section 4, and the gas is discharged from the pre-gas separation section exhaust pipe 5 to obtain the degassed produced fluid. Open the handle flange butterfly valve 6 to allow the degassed produced fluid to enter the pre-water separation section 7 through the liquid phase outlet pipe of the gas-liquid separator. Due to the density difference between oil and water, the degassed produced fluid undergoes preliminary oil-water separation in the separation pipe. Under the action of gravity, the denser water phase concentrates in the pre-water separation section 7, and the less dense oil phase concentrates in the purified oil outlet section 14. The oil-water emulsion is distributed in the electrostatic coalescence section 9.
[0050] When the high-voltage AC insulated electrode 10 is connected to the high-voltage power supply 12, the dispersed water particles in the oil-water emulsion will become polarized under the action of the electric field in the electrostatic coalescence section 9. The positive and negative charges between the polarized water droplets will attract and induce each other, causing the droplets to stretch and deform and move relative to each other. During the deformation process, due to the presence of the electric field, the water droplets will be arranged in a chain-like manner in the direction of the electric field, that is, forming a "water chain". The positive and negative poles of the adjacent water droplets will attract each other, and eventually merge into larger water droplets under this attraction, which will settle and separate from the crude oil and be discharged from the oily wastewater outlet pipe 15 along with the pre-separated water. The crude oil after electrostatic coalescence will be discharged from the purified oil outlet section 14 above.
[0051] In addition, samples can be taken from the produced fluid inlet pipe 1 via a sampling branch pipe 2, and the physicochemical properties of the produced fluid can be tested. Samples can also be taken from the purified oil outlet pipe 11 via a sampling branch pipe 13, and the physicochemical properties of the produced fluid can be tested. Finally, samples can be taken from the oily wastewater outlet pipe 15 via a sampling branch pipe 16, and the physicochemical properties of the oily wastewater can be tested.
[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A high-frequency electro-coalescing oil-water separation device for pre-gas separation and pre-water separation, characterized in that, It includes a vertically arranged gas-liquid separator and a separation pipe. The gas-liquid separator is provided with a pre-gas separation section. The top of the gas-liquid separator is provided with a pre-gas separation section exhaust pipe. The side wall of the gas-liquid separator is provided with a liquid phase outlet pipe. The liquid phase outlet pipe is spaced apart from the top of the gas-liquid separator. The gas-liquid separator is connected to the separation pipe via a liquid phase outlet pipe; The separation tube is equipped with a high-voltage AC insulated electrode, and the upper and lower ends of the high-voltage AC insulated electrode are equipped with high-voltage electrode insulated cover plates. The high-voltage electrode insulated cover plates divide the separation tube into three sections, wherein the upper section is the purified oil outlet section, the middle section is the electrostatic coalescence section, and the lower section is the pre-water separation section. The electrostatic coalescence section is located at the top of the liquid phase outlet pipe.
2. The high-frequency electro-coalescence oil-water separation device for pre-gas separation and pre-water separation according to claim 1, characterized in that, The number of separation tubes is multiple, and the multiple separation tubes are vertically arranged parallel to each other around the gas-liquid separation tank. The multiple gas-liquid separation tanks are respectively connected to the multiple separation tubes through liquid phase outlet pipes. The gas-liquid separator includes a cylindrical vertical pipe and a conical pipe disposed at the lower end of the cylindrical vertical pipe; The bottom of the gas-liquid separator is provided with an L-shaped produced liquid inlet pipe, and a sample sampling branch pipe is provided on the produced liquid inlet pipe.
3. The high-frequency electro-coalescence oil-water separation device for pre-gas separation and pre-water separation according to claim 2, characterized in that, The number of separation tubes is four, and the four separation tubes are arranged vertically around the gas-liquid separator in parallel with each other. The liquid phase outlet pipe of the gas-liquid separator is equipped with a handle flange butterfly valve; The separation tube includes a cylindrical vertical tube and a tapered tube disposed at the lower end of the cylindrical vertical tube, and the bottom of the separation tube is connected to an L-shaped tube; The diameters of the cylindrical vertical tube and the conical tube in the separation tube are smaller than the diameters of the cylindrical vertical tube and the conical tube in the gas-liquid separator.
4. The high-frequency electro-coalescence oil-water separation device for pre-gas separation and pre-water separation according to claim 2, characterized in that, The number of separation tubes is two, and the two separation tubes are vertically arranged parallel to each other on both sides of the gas-liquid separation tank. The gas-liquid separation tank is connected to the two separation tubes through liquid phase outlet pipes. The horizontal pipes in the L-shaped tubes at the bottom of the two separation tubes are connected to the oily wastewater outlet pipe. The oily wastewater outlet pipe is equipped with an oily wastewater outlet pipe sampling branch pipe. The oily wastewater outlet pipe is connected to the wastewater treatment system.
5. The high-frequency electro-coalescence oil-water separation device for pre-gas separation and pre-water separation according to claim 1, characterized in that, The purified oil outlet section is provided with a purified oil outlet pipe on its side wall, and a purified oil outlet pipe sampling branch pipe is provided on the purified oil outlet pipe. The electrostatic coalescence section includes a high-voltage AC insulated electrode and a high-voltage power supply, wherein the high-voltage AC insulated electrode is connected to the high-voltage power supply.
6. The high-frequency electro-coalescence oil-water separation device for pre-gas separation and pre-water separation according to claim 1, characterized in that, The electrostatic coalescing section and the pre-water separation section are connected by a flange; the length of the electrostatic coalescer does not exceed 10,000 mm.
7. A method for pre-gas separation-pre-water electro-coalescing oil-water separation, characterized in that, The pre-gas-pre-water high-frequency electro-coalescing oil-water separation device according to any one of claims 1-6 includes the following steps: The produced fluid enters the gas-liquid separator through the produced fluid inlet pipe for gas-liquid separation to obtain degassed produced fluid; After degassing, the produced fluid enters the separation tube through the liquid phase outlet pipe on the gas-liquid separator, where it is automatically separated to obtain oil phase, free water, and oil-water emulsion; the oil phase and free water are discharged through the purified oil outlet section and the pre-water separation section in the separation tube, respectively. The oil-water emulsion in the produced fluid is separated into oil and water phases under the action of the electric field in the electrostatic coalescence section of the separation tube, and then discharged through the purified oil outlet section and the pre-water separation section of the separation tube, respectively.
8. The pre-gas-pre-water electro-coalescing oil-water separation method according to claim 7, characterized in that, The high-voltage power supply input voltage range in the electrostatic coalescence section is 6 kV-15 kV, and the input electric field frequency range is 500 Hz-20 kHz.
9. The pre-gas-pre-water electro-coalescing oil-water separation method according to claim 7, characterized in that, It also includes sampling the produced fluid through sampling branch pipes installed on the produced fluid inlet pipe; The purified oil is sampled by installing a sampling branch pipe on the purified oil outlet pipe. A sampling branch pipe is installed on the oily wastewater outlet pipe to sample the oily wastewater.
10. The application of the pre-gas-pre-water high-frequency electro-coalescence oil-water separator according to any one of claims 1-6 in the oil-water separation of produced fluids in oilfields, characterized in that, The water content of the produced fluid from the oilfield is above 70%.