Membrane-method seawater deoxidation treatment system and method for offshore oil platform

Abstract

The invention discloses a membrane-method seawater deoxidation treatment system and method for an offshore oil platform, and relates to the field of ocean engineering. According to the method, the turbidity of the seawater is reduced to be less than or equal to 0.1 NTU and the like through precision filtration, more than or equal to 99.9% of microorganisms are removed through microorganism killing, and then treatment is performed through a three-stage vacuum deoxidation membrane module, so that the dissolved oxygen of the seawater is less than or equal to 50ppb, and the total deoxidation efficiency is more than or equal to 99.8%. The system comprises a precise filtering device, a microorganism killing device, a three-stage vacuum deoxidation membrane assembly and the like, integrates seawater softening, active oxidation substance removal and a purge gas regeneration circulation system, solves the problems of huge equipment, low deoxidation efficiency, membrane pollution and the like in the prior art, realizes miniaturization, low cost and long-period efficient operation, and meets the strict requirements of an offshore platform.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ocean engineering, in particular to a membrane seawater deoxidation treatment system and method for offshore oil platforms. BACKGROUND

[0002] Offshore oil platforms need to continuously inject deoxidized seawater to prevent pipeline and equipment corrosion and the breeding of aerobic bacteria. The breeding of bacteria caused by excessive dissolved oxygen in the reinjection seawater will block the underground oil production pipelines and oil reservoir pores, reducing the oilfield production rate. The existing seawater deoxidation methods have many defects: vacuum tower deoxidation is currently the most widely used method on offshore oil platforms, but it has low deoxidation efficiency, large and heavy equipment, high auxiliary reagent consumption and high operating cost. In addition, it is difficult for the oxygen content of the outlet water to meet the quality standard requirements of the reinjection water, and a large amount of deoxidation reagent is consumed for deep deoxidation of seawater. Chemical reagent deoxidation relies on the addition of deoxidation reagents in seawater to achieve deoxidation, but it has the problems of large reagent consumption and high operating cost, and is usually used as an auxiliary means and rarely used alone. Supergravity deoxidation uses the supergravity field generated by the high-speed rotation of a centrifuge to achieve gas-liquid intensified mass transfer, thereby achieving seawater deoxidation. However, the supergravity deoxidation equipment has the disadvantages of large maintenance workload and large unit vibration. Although membrane deoxidation has potential for deoxidation in the field of ultrapure water, it still faces technical bottlenecks such as membrane assembly pollution, rapid deoxidation efficiency decay and large purge gas consumption when applied to the seawater reinjection conditions of offshore oil platforms. SUMMARY

[0003] To solve the above problems, the present application aims to provide a membrane seawater deoxidation treatment system and method for offshore oil platforms, which integrates precise filtration, microbial killing, three-stage membrane deoxidation and gas regeneration systems. The problems of severe membrane pollution, low deoxidation efficiency and large purge gas consumption under seawater conditions are solved. On the one hand, the characteristics of small size and light weight of the deoxidation membrane assembly are utilized to meet the harsh requirements of equipment layout on offshore oil platforms. On the other hand, the integration of precise filtration to remove particulate matter, microbial killing to remove bacteria and three-stage high-efficiency membrane deoxidation methods, as well as innovative design of the device, effectively solve the problems of severe membrane pollution, rapid efficiency decay and large purge gas consumption in membrane seawater deoxidation. The purpose of low-cost, long-period and high-efficiency operation of membrane seawater deoxidation is ultimately achieved.

[0004] To achieve the above purpose, the technical solution of the present application is as follows: A membrane seawater deoxidation treatment system for offshore oil platforms, comprising a precise filtration device, a microbial killing device, a first-stage vacuum deoxidation membrane assembly, a second-stage vacuum deoxidation membrane assembly, a third-stage vacuum deoxidation membrane assembly, a purge gas storage and supply device and a vacuum pumping device. The vacuum deoxidation membrane assembly comprises a seawater flow cavity, a gas flow cavity and a deoxidation membrane. The seawater flow cavity and the gas flow cavity are located on both sides of the deoxidation membrane and are separated by the deoxidation membrane. The precision filtration device has an inlet connected to a seawater supply pipeline, an outlet connected to a microbial sterilization device, an outlet connected to the seawater flow chamber in the primary vacuum deoxygenation membrane assembly, an outlet connected to the seawater flow chamber in the secondary vacuum deoxygenation membrane assembly, an outlet connected to the seawater flow chamber in the tertiary vacuum deoxygenation membrane assembly, and an outlet connected to the deoxygenated seawater pipeline. The inlet of the purge gas storage and supply device is connected to the purge gas supply pipeline, and the outlet of the purge gas storage and supply device is connected to the inlet of the gas flow chamber of the first-stage vacuum deoxygenation membrane assembly, the gas flow chamber of the second-stage vacuum deoxygenation membrane assembly, and the gas flow chamber of the third-stage vacuum deoxygenation membrane assembly, respectively. The outlets of the gas flow chambers of the first-stage, second-stage, and third-stage vacuum deoxygenation membrane assemblies are directly connected to the vacuum pumping device.

[0005] Furthermore, it also includes a seawater softening device and an active oxidizing substance removal device. The inlet of the seawater softening device is connected to the outlet of the precision filtration device, and the outlet of the seawater softening device is connected to the inlet of the microbial sterilization device. The seawater softening device adopts one of nanofiltration membrane filtration, reverse osmosis membrane filtration, or ion exchange resin filtration. The active oxidizing substance removal device is installed at the outlet of the microbial sterilization device, and the active oxidizing substance removal device adopts activated carbon filtration or sodium sulfite dosing device.

[0006] Furthermore, it also includes a deoxygenation regeneration device, which includes a pressurization device and a purge gas regeneration device. The inlet of the pressurization device is connected to the outlet of the vacuum device, the outlet of the pressurization device is connected to the inlet of the purge gas regeneration device, and the outlet of the purge gas regeneration device is connected to the inlet of the purge gas storage and supply device. The oxygen-enriched purge gas can be returned to the deoxygenation membrane module for reuse after being processed by the pressurization device and the purge gas regeneration device.

[0007] Furthermore, the purge gas regeneration device includes a shell, a deoxygenated particle filling area, a retractable perforated packing pressure plate, a retractable perforated packing support rod, and a purge gas distribution area. The lower outer part of the shell is provided with a discharge port for pulverized deoxidizing particles, a purge gas inlet, and a deoxidizing particle outlet. The upper outer part of the shell is provided with a purge gas outlet and a deoxidizing particle inlet. A perforated ventilated support plate is horizontally fixed in the lower inner part of the shell. The perforation diameter of the perforated ventilated support plate is smaller than the minimum particle size of the deoxidizing particles. A deoxidizing particle filling area is provided at the upper part of the perforated ventilated support plate, and a purge gas distribution area is provided at the lower part. A perforated ventilated pressure plate is horizontally arranged above the deoxidizing particle filling area. A cylinder is provided inside the shell to control the up and down movement of the perforated ventilated pressure plate. The upper part of the cylinder is installed on the top of the shell and connected to the shell through a hanging column. The lower end of the cylinder is connected and fixed to the perforated ventilated pressure plate. The perforated air pressure plate is connected to the top of the shell through two retractable support guide devices. The deoxidizing particle inlet is lower than the highest point of the stroke of the perforated air pressure plate and is connected to the deoxidizing particle filling area. The deoxidizing particle outlet is higher than the perforated air support plate and is connected to the deoxidizing particle filling area. The side wall of the deoxidizing particle filling area is provided with two or three layers of gas redistribution ring plates. The purge gas distribution area is provided with several purge gas releasers evenly distributed along the circumference of the cross section. One end of each purge gas releaser is closed, and the other end is connected to each other through a gas collection box at the center of the cross section of the shell. The gas collection box is connected to the purge gas inlet through a purge gas distribution pipe. The upper part of the side wall of the purge gas releaser is provided with a gas release nozzle.

[0008] Furthermore, the precision filtration device includes a filter element mounting plate, a housing, copper electrodes, a wastewater chamber, a DC control power supply, aluminum electrodes, filter elements, and a clean water chamber; The sewage chamber is equipped with a seawater inlet for a precision filtration device, and the water purification chamber is equipped with a seawater outlet for a precision filtration device. The sewage chamber and the water purification chamber are located on both sides of the filter element. The copper electrode is located at the seawater inlet of the precision filtration device in the sewage chamber, and the aluminum electrode is located on the other layer symmetrical to the copper electrode in the sewage chamber. The copper electrode and the aluminum electrode are connected to the positive terminal of the DC control power supply, and the negative terminal of the DC control power supply is connected to the outer casing. The microbial sterilization device is equipped with a medium-pressure ultraviolet germicidal lamp and a transparent quartz baffle perpendicular to the water flow direction. The length of the transparent quartz baffle is greater than the inlet and outlet pipe diameters. The primary, secondary, and tertiary vacuum deoxygenation membrane components all include a seawater inlet, a seawater outlet, a seawater flow chamber, a deoxygenation membrane, a gas flow chamber, a purge gas inlet, and a purge gas outlet. The seawater flow chamber is equipped with baffles, each with a notch for seawater flow. The notches of adjacent baffles are symmetrically arranged on both sides. Seawater needs to vertically scour the deoxygenation membrane between the baffles to flow to the notches of adjacent baffles.

[0009] To achieve the above objectives, the present invention also discloses a treatment method for a membrane-based seawater deoxygenation system used on offshore oil platforms, comprising the following steps: S1: Seawater enters the precision filtration device, where the turbidity of the seawater is reduced to ≤0.1NTU, the silt density index (SDI) is reduced to ≤3, the total suspended solids concentration is reduced to ≤5mg / L, and the maximum particle diameter is ≤1μm. S2: Seawater enters the microbial sterilization device, where ≥99.9% of bacteria, viruses, and microorganisms in the seawater are killed through microbial sterilization treatment; S3: Seawater enters the membrane deoxygenation unit, which includes a three-stage vacuum deoxygenation membrane module. After treatment by the membrane deoxygenation unit, the dissolved oxygen content in the seawater is ≤50ppb, and the total deoxygenation efficiency is ≥99.8%. The seawater flow chamber and the gas flow chamber are located on both sides of the deoxygenation membrane and separated by the deoxygenation membrane. The working conditions are as follows: seawater enters the seawater flow chamber on the side of the deoxygenation membrane, with an inlet dissolved oxygen content of 8000~10000 ppb. The seawater flow chamber operates under positive pressure, with a pressure of 0.15~0.6MPa and a temperature of 5~40℃. The gas flow chamber operates under vacuum, with a pressure of 8~15kPa. The purge gas enters the vacuum gas flow chamber, with an inlet purge gas oxygen content of ≤0.1%. The deoxygenation membrane is made of hydrophobic microporous membrane material with a pore size of 60~90μm. Utilizing the water-blocking and air-permeable properties of the deoxygenation membrane, dissolved oxygen in the seawater permeates through the deoxygenation membrane and enters the gas flow chamber from the seawater flow chamber. The oxygen-enriched purge gas carrying oxygen is discharged from the system through a vacuum device.

[0010] Furthermore, before S2, a seawater softening device is installed at the outlet of the precision filtration device to control the total concentration of calcium and magnesium ions in the seawater to ≤100ppm; before S3, an active oxidizing substance removal device is installed at the outlet of the microbial killing device to control the oxidation-reduction potential (ORP) in the seawater to ≤250~350mV.

[0011] Furthermore, the oxygen-enriched purge gas discharged from the vacuum pump enters the pressurization device, where the pressure is increased to 0.6~0.8MPa. The oxygen-enriched purge gas discharged from the pressurization device then enters the deoxygenation and regeneration device. After deoxygenation and regeneration, the dissolved oxygen content in the purge gas is ≤0.1%, and the pressure is 0.4~0.8MPa. The regenerated gas is then regulated in pressure and flow rate before entering the three-stage vacuum deoxygenation membrane assembly, ultimately achieving the recycling of the purge gas.

[0012] Furthermore, the deoxygenation regeneration device employs a carbon molecular sieve adsorption device, or a catalytic reaction device including a gas heater, a catalytic reactor, and a gas cooler. When a carbon molecular sieve adsorption device is used, after deoxygenation by carbon molecular sieve adsorption, the purge gas enters the vacuum deoxygenation membrane module after the flow rate is adjusted, which can reduce the purge gas consumption by ≥90%. When a catalytic reaction device is used, the high-pressure oxygen-enriched purge gas entering the deoxygenation and regeneration device first enters the gas heater, then enters the catalytic reaction device. After deoxygenation and regeneration, it enters the gas cooler, where the temperature is reduced to 35°C. Then, the purge gas enters the vacuum deoxygenation membrane module, which can reduce purge gas consumption by ≥95%. Within the catalytic reaction device, the oxygen-enriched purge gas is mixed with associated methane gas from the oilfield and undergoes a catalytic oxidation reaction using an alumina-supported nickel-based catalyst. The gas heater operates at a temperature of 760~960°C and a pressure of 0.6~0.8 MPa. Alternatively, the oxygen-enriched purge gas is mixed with hydrogen and undergoes a catalytic oxidation reaction using an alumina-supported palladium catalyst. The gas heater operates at a temperature of 150~250°C and a pressure of 0.6~0.8 MPa.

[0013] Furthermore, the precision filtration device in S1 has a filtration accuracy of ≤1μm, and the filter material is one of glass fiber, polysulfone, polyacrylonitrile, silicon dioxide, and aluminum oxide. The microbial sterilization device in S2 is equipped with a medium-pressure ultraviolet germicidal lamp, with an internal air pressure of 1×10⁻⁶. 5 ~1×10 6 Pa, seawater residence time 0.5~1.5 seconds, radiation intensity ≥30mW / cm 2 ; The vacuum deoxidation membrane material in S3 is one of polytetrafluoroethylene, polyvinylidene fluoride and polypropylene, with an inner diameter of 200~300μm and a wall thickness of 50~100μm. The purge gas in S3 is associated gas from the oilfield. By adjusting the purge gas flow rate, the dissolved oxygen content of the purge gas at the outlet of the gas flow chamber is controlled to be ≤1%. Alternatively, the purging gas in S3 may be nitrogen with a purity of ≥99.9%.

[0014] Beneficial effects: 1. Miniaturization and Lightweight Requirements: The membrane-based seawater deoxygenation method of this invention can achieve efficient deoxygenation under positive pressure operating conditions, with a seawater pressure drop ≤50kPa. It consumes only electricity, resulting in low operating costs and low energy consumption. Furthermore, leveraging the miniaturization and lightweight characteristics of the deoxygenation membrane modules, the membrane-based seawater deoxygenation equipment has a small footprint, is lightweight, and can be flexibly arranged using a modular approach, requiring no dedicated infrastructure investment. This solves the problems of low efficiency, bulky and heavy equipment, and high consumption of auxiliary reagents associated with current vacuum tower deoxygenation methods used on platforms, ultimately meeting the stringent requirements for equipment layout on offshore oil platforms.

[0015] 2. Zero deoxygenating agent consumption and high deoxygenation efficiency: Currently used methods such as vacuum tower deoxygenation and high-gravity deoxygenation generally have a deoxygenation efficiency of ≤97%, and the dissolved oxygen in the outlet seawater is generally ≥200 ppb. Large amounts of deoxygenating agents are needed to meet the requirement of ≤50 ppb for seawater reinjection from offshore oil platforms, which not only causes severe corrosion to equipment but also results in high operating costs. The method of this invention can control the dissolved oxygen in seawater to ≤50 ppb, and can even control it as low as 10 ppb, with a high deoxygenation efficiency of ≥99.8%, and requires no additional deoxygenating agents.

[0016] 3. High operational flexibility and good operational stability: Currently used vacuum packed towers and ultra-gravity deoxygenation equipment cannot achieve independent control of the gas and liquid phases, and are prone to flooding and mist entrainment, resulting in low operational flexibility. The method of this invention can achieve non-direct contact between the gas and liquid phases, truly realizing independent control of the gas and liquid phases. It can achieve efficient deoxygenation of seawater under positive pressure conditions in the aqueous phase and high vacuum conditions in the gas phase, and has the advantages of high operational flexibility and good operational stability.

[0017] 4. Low membrane fouling and long service life: While membrane deoxygenation has some applications in ultrapure water, its application in seawater reinjection on offshore oil platforms still faces technical bottlenecks such as severe membrane fouling, rapid degradation of deoxygenation efficiency, and short service life. This invention proposes a novel membrane-based seawater deoxygenation method and device suitable for seawater reinjection on offshore oil platforms. It integrates precision filtration, microbial sterilization, and a three-stage membrane deoxygenation system. Furthermore, the method of this invention also integrates seawater hardness control and seawater oxidation-reduction potential (ORP) control, effectively solving the above-mentioned problems.

[0018] 5. Low operating cost: The method and apparatus of this invention are equipped with a deoxygenation regeneration device for the purging gas, which can reduce purging gas consumption by more than 90%, thereby reducing the cost of purchasing high-purity nitrogen for offshore oil operation platforms. Furthermore, this invention develops a deoxygenation membrane module suitable for associated gas from oil fields, utilizing the abundant associated gas resources of offshore oil platforms to replace high-purity nitrogen and achieve low-cost operation of seawater deoxygenation.

[0019] 6. The membrane module is equipped with multi-stage baffles to enhance the gas-liquid mass transfer process. The membrane module device design is more compact and efficient, making it more suitable for the demanding space utilization requirements of offshore oil platforms.

[0020] 7. The seawater precision filter is equipped with electrolytic copper and aluminum devices. Copper ions effectively kill microorganisms in seawater, while aluminum ions hydrolyze to form aluminum hydroxide flocs, which combine with copper ions and adhere to the surface of the precision filter element. As seawater passes through the filter element, it undergoes highly efficient sterilization, extending the filter element's lifespan. Furthermore, the electrolytic copper ions are located near the precision filter inlet. With the help of water flow, the bactericidal copper ions are evenly diffused throughout the seawater and enter the downstream treatment system, providing long-lasting sterilization.

[0021] 8. The ultraviolet microbial sterilization device uses a high-efficiency medium-pressure ultraviolet lamp and is equipped with a turbulent light-transmitting quartz baffle inside. This device not only effectively removes viruses and microorganisms in seawater, but also carries out secondary sterilization of bacteria and larvae, preventing microbial contamination of the deoxygenation membrane components.

[0022] 9. The purge gas regeneration device is equipped with a deoxygenated particulate filling and compaction mechanism, which not only ensures more uniform filling of deoxygenated particles but also facilitates the replacement of deoxygenated particles in the regeneration device. In addition, the internal sidewall of the regeneration device is equipped with a short-flow prevention baffle, and the lower part of the purge gas is equipped with a gas equalization device, which allows the purge gas to pass through the deoxygenated particle filling area more evenly and make full contact with the deoxygenated particles, thereby improving the deoxygenation efficiency of the device. Attached Figure Description

[0023] 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 undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the precision filtration device in the membrane-based seawater deoxygenation system for offshore oil platforms according to an embodiment of the present invention; Figure 2 This refers to the microbial eradication device in the membrane-based seawater deoxygenation system for offshore oil platforms described in this embodiment of the invention. Figure 3 This is a schematic diagram of the vacuum deoxygenation membrane module in the membrane-based seawater deoxygenation system for offshore oil platforms according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the purge gas regeneration device in the membrane-based seawater deoxygenation system for offshore oil platforms according to an embodiment of the present invention. Figure 5 This is a process flow diagram of the membrane-based seawater deoxygenation treatment method for offshore oil platforms according to an embodiment of the present invention.

[0024] In the diagram, 1-Precision filtration device, 101-Filter element mounting plate, 102-Outer shell, 103-Copper electrode, 104-Sewage chamber, 105-DC control power supply, 106-Aluminum electrode, 107-Filter element, 108-Clean water chamber, 11-Seawater inlet of precision filtration device, 12-Seawater outlet of precision filtration device, 2-Microbial sterilization device, 201-Medium-pressure ultraviolet germicidal lamp, 202-Transparent quartz baffle, 21-Inlet of microbial sterilization device, 22-Outlet of microbial sterilization device, 3-Vacuum deoxygenation membrane assembly, 301-Seawater inlet, 302-Seawater outlet, 303-Seawater flow chamber, 304-Deoxygenation membrane, 305-Gas flow chamber, 306-Purge gas inlet, 307-Purge gas outlet, 308- Baffle, 309-Notch, 4-Purge gas regeneration device, 401-Shell, 402-Powdered deoxidizing particle residue discharge port, 403-Purge gas inlet, 404-Perforated ventilated support plate, 405-Deoxidizing particle outlet, 406-Gas redistribution ring plate, 407-Deoxidizing particle inlet, 408-Purge gas outlet, 409-Deoxidizing particle, 410-Hanging column, 411-Cylinder, 412-Perforated ventilated pressure plate, 413-Supporting guide device, 414-Purge gas release device, 415-Gas collection box, 416-Purge gas distribution pipe, 417-Gas release nozzle, 5-Purge gas storage and supply device, 6-Vacuum device, 7-Seawater softening device, 8-Active oxidizing substance removal device, 9-Pressure booster device. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] Example 1 See Figures 1-4 A membrane-based seawater deoxygenation system for offshore oil platforms includes a precision filtration device 1, a microbial sterilization device 2, a primary vacuum deoxygenation membrane assembly 3, a secondary vacuum deoxygenation membrane assembly 3, a tertiary vacuum deoxygenation membrane assembly 3, a purge gas storage and supply device 5, and a vacuum pumping device 6. The vacuum deoxygenation membrane assembly 3 includes a seawater flow chamber 303, a gas flow chamber 305, and a deoxygenation membrane 304. The seawater flow chamber 303 and the gas flow chamber 305 are located on both sides of the deoxygenation membrane 304 and are separated by the deoxygenation membrane 304. The precision filter device 1 is connected to the seawater supply pipeline at its inlet, and to the microbial sterilization device 2 at its outlet. The microbial sterilization device outlet 22 is connected to the seawater flow chamber 303 inlet of the first-stage vacuum deoxygenation membrane assembly 3. The seawater flow chamber 303 outlet of the first-stage deoxygenation membrane assembly 3 is connected to the seawater flow chamber 303 inlet of the second-stage vacuum deoxygenation membrane assembly 3. The seawater flow chamber 303 outlet of the second-stage vacuum deoxygenation membrane assembly 3 is connected to the seawater flow chamber 303 inlet of the third-stage vacuum deoxygenation membrane assembly 3. The seawater flow chamber 303 outlet of the third-stage vacuum deoxygenation membrane assembly 3 is connected to the deoxygenated seawater pipeline. The inlet of the purge gas storage and supply device 5 is connected to the purge gas supply pipeline, and the outlet of the purge gas storage and supply device 5 is connected to the gas flow chamber 305 inlet of the first-stage vacuum deoxygenation membrane assembly 3, the gas flow chamber 305 inlet of the second-stage vacuum deoxygenation membrane assembly 3, and the gas flow chamber 305 inlet of the third-stage vacuum deoxygenation membrane assembly 3, respectively. The gas flow chamber 305 outlet of the first-stage vacuum deoxygenation membrane assembly 3, the gas flow chamber 305 outlet of the second-stage vacuum deoxygenation membrane assembly 3, and the gas flow chamber 305 outlet of the third-stage vacuum deoxygenation membrane assembly 3 are directly connected to the vacuum pumping device 6.

[0027] This embodiment clarifies the core components and connections of the system. By connecting three-stage vacuum deoxygenation membrane components in series, high-efficiency deoxygenation is achieved by utilizing the water-blocking and air-permeable characteristics of the deoxygenation membrane and the pressure difference between the gas and liquid sides (0.15~0.6MPa positive pressure on the seawater side and 8~15kPa vacuum on the gas side). The dissolved oxygen in seawater can be controlled at ≤50ppb, and can be controlled as low as 10ppb. The deoxygenation efficiency is high, ≥99.8%, and no auxiliary deoxygenation agents are required. This solves the problems of low deoxygenation efficiency and bulky equipment of traditional vacuum towers. In addition, the gas and liquid phases are controlled independently, avoiding problems such as flooding, and the operation is highly stable.

[0028] In a specific example, the system also includes a seawater softening device 7 and an active oxidizing substance removal device 8. The inlet of the seawater softening device 7 is connected to the outlet of the precision filtration device 1, and the outlet of the seawater softening device 7 is connected to the inlet of the microbial sterilization device 2. The seawater softening device 7 employs one of nanofiltration membrane filtration, reverse osmosis membrane filtration, or ion exchange resin filtration. The active oxidizing substance removal device 8 is installed at the outlet of the microbial sterilization device 2, and the active oxidizing substance removal device 8 employs activated carbon filtration or a sodium sulfite dosing device.

[0029] This embodiment adds a seawater softening device and an active oxidant removal device. Seawater softening can reduce the concentration of calcium and magnesium ions to ≤100ppm, reducing membrane fouling; active oxidant removal controls the ORP to ≤250~350mV, avoiding damage to the membrane by oxidants, further alleviating membrane fouling, extending the membrane module life, and improving system adaptability.

[0030] In a specific example, a deoxygenation regeneration device is also included, which includes a pressurizing device 9 and a purge gas regeneration device 4. The inlet of the pressurizing device 9 is connected to the outlet of the vacuum device 6, the outlet of the pressurizing device 9 is connected to the inlet of the purge gas regeneration device 4, and the outlet of the purge gas regeneration device 4 is connected to the inlet of the purge gas storage and supply device 5. The oxygen-enriched purge gas can be returned to the deoxygenation membrane assembly 3 for reuse after being processed by the pressurizing device 9 and the purge gas regeneration device 4.

[0031] This embodiment introduces a deoxygenation regeneration device (including a pressurization device 9 and a purge gas regeneration device 4) to realize the recycling of oxygen-enriched purge gas, significantly reduce purge gas consumption, reduce external purchase costs, and is especially suitable for resource-constrained scenarios on offshore platforms, thereby improving the system's economic efficiency.

[0032] In a specific example, the purge gas regeneration device 4 includes a housing 401, a deoxygenated particle filling area, a telescopic perforated packing pressure plate, a telescopic perforated packing support rod, and a purge gas distribution area. The lower outer part of the shell 401 is provided with a pulverized deoxidation particle residue discharge port 402, a purging gas inlet 403, and a deoxidation particle discharge port 405. The upper outer part of the shell 401 is provided with a purging gas outlet 408 and a deoxidation particle inlet 407. A perforated ventilated support plate 404 is horizontally fixed in the lower inner part of the shell 401. The perforation diameter of the perforated ventilated support plate 404 is smaller than the minimum particle size of the deoxidation particles 409. A deoxidation particle filling area is provided on the upper part of the perforated ventilated support plate 404, and a purging gas distribution area is provided on the lower part. A perforated ventilated pressure plate 412 is horizontally provided above the deoxidation particle filling area. A cylinder 411 is provided inside the shell 401 to control the up and down movement of the perforated ventilated pressure plate 412. The upper part of the cylinder 411 is installed on the top of the shell 401 and connected to the shell 401 through a hanging column 410. The lower end of the cylinder 411 is connected to the perforated ventilated pressure plate 412. 12. The perforated and breathable pressure plate 412 is connected to the top of the shell 401 via two retractable support guide devices 413. The deoxidizing particle inlet 407 is lower than the highest point of the stroke of the perforated and breathable pressure plate 412 and is connected to the deoxidizing particle filling area. The deoxidizing particle outlet 405 is higher than the perforated and breathable support plate 404 and is connected to the deoxidizing particle filling area. The side wall of the deoxidizing particle filling area is provided with two or three layers of gas redistribution ring plates 406. The purge gas distribution area is provided with several purge gas releasers 414 evenly distributed along the circumference of the cross section. One end of each purge gas releaser 414 is closed, and the other end is connected to each other at the center of the cross section of the shell 401 via a gas collection box 415. The gas collection box 415 is connected to the purge gas inlet 403 via a purge gas distribution pipe 416. The upper part of the side wall of the purge gas releaser 414 is provided with a gas release nozzle 417.

[0033] This embodiment refines the structure of the purge gas regeneration device. The deoxygenated particles are flattened and compacted through perforated gas-permeable pressure plates and cylinders. The gas redistribution ring plate and purge gas release device ensure uniform gas contact with the particles, thereby improving regeneration efficiency. At the same time, it facilitates particle replacement, ensures long-term efficient operation of the regeneration device, and supports the stability of purge gas recycling.

[0034] In a specific example, the precision filtration device includes a filter element mounting plate 101, a housing 102, a copper electrode 103, a wastewater chamber 104, a DC control power supply 105, an aluminum electrode 106, a filter element 107, and a purified water chamber 108. The sewage chamber 104 is equipped with a seawater inlet 11 for a precision filtration device, and the water purification chamber 108 is equipped with a seawater outlet 12 for a precision filtration device. The sewage chamber 104 and the water purification chamber 108 are located on both sides of the filter element 107. The copper electrode 103 is located at the seawater inlet of the precision filtration device 11 in the sewage chamber 104, and the aluminum electrode 106 is located on the other side of the copper electrode 103 in the sewage chamber 104. The copper electrode 103 and the aluminum electrode 106 are connected to the positive terminal of the DC control power supply 105, and the negative terminal of the DC control power supply 105 is connected to the outer casing 102. The microbial sterilization device 2 is equipped with a medium-pressure ultraviolet germicidal lamp 201 and a transparent quartz baffle 202 perpendicular to the water flow direction. The length of the transparent quartz baffle 202 is greater than the inlet and outlet pipe diameters. This embodiment clearly demonstrates that the precision filtration device integrates electrolytic copper-aluminum electrodes, with copper ions sterilizing and aluminum ions forming flocs to protect the filter element and extend its lifespan; the medium-pressure ultraviolet lamp and quartz baffle of the microbial sterilization device enhance the sterilization effect; the baffle design of the vacuum deoxygenation membrane component forces seawater to vertically wash the membrane surface, enhancing mass transfer, making the device more compact, and adapting to platform space requirements.

[0035] The first-stage vacuum deoxygenation membrane assembly 3, the second-stage vacuum deoxygenation membrane assembly 3, and the third-stage vacuum deoxygenation membrane assembly 3 all include a seawater inlet 301, a seawater outlet 302, a seawater flow chamber 303, a deoxygenation membrane 304, a gas flow chamber 305, a purge gas inlet 306, and a purge gas outlet 307. The seawater flow chamber 303 is provided with a baffle 308 inside, and the baffle 308 has a notch 309 for seawater to flow through. The notches 309 of adjacent baffles 308 are symmetrically arranged on both sides. The seawater needs to vertically scour the deoxygenation membrane 304 between the baffles 308 to flow to the notch 309 of the adjacent baffles 308.

[0036] It should be noted that in this embodiment, the three-stage vacuum deoxygenation membrane assembly 3 is connected in series via the seawater flow chamber 303: The outlet of the seawater flow chamber 303 of the primary vacuum deoxygenation membrane assembly 3 is connected to the inlet of the seawater flow chamber 303 of the secondary vacuum deoxygenation membrane assembly 3. The outlet of the seawater flow chamber 303 of the secondary vacuum deoxygenation membrane module 3 is connected to the inlet of the seawater flow chamber 303 of the tertiary vacuum deoxygenation membrane module 3. After pretreatment (precision filtration, microbial sterilization, etc.), the seawater flows sequentially through the seawater flow chambers 303 of the first, second and third stage components, and is finally discharged from the outlet of the seawater flow chamber 303 of the third stage component and enters the deoxygenated seawater pipeline.

[0037] The core function of the three-stage components is to utilize the water-blocking and air-permeable properties of the deoxygenation membrane 304 to allow dissolved oxygen in the seawater to permeate through the membrane into the gas flow chamber 305 via the pressure difference between the positive pressure on the seawater side (0.15~0.6MPa) and the vacuum on the gas side (8~15kPa), and then be carried out by the purge gas.

[0038] Stepwise deoxygenation is achieved through a three-stage series connection: The primary component mainly removes most of the dissolved oxygen from seawater, completing the initial deoxygenation process; The secondary component further deoxygenates the seawater after primary treatment, reducing the dissolved oxygen concentration. The three-stage component, as a deep processing unit, ultimately controls the dissolved oxygen in seawater to ≤50ppb, ensuring a total deoxygenation efficiency of ≥99.8%, meeting the stringent standards for seawater reinjection from offshore oil platforms.

[0039] The three-stage components have identical structures, each including a seawater flow chamber 303, a gas flow chamber 305, a deoxygenation membrane 304 (a hydrophobic microporous membrane with a pore size of 60-90 μm), and internal baffles 308 that enhance mass transfer (the notches 309 of adjacent baffles 308 are symmetrically arranged, forcing seawater to vertically scour the membrane surface). This structural consistency ensures the stability of the three-stage treatment process, while the series design, through a "gradual deepening" approach, compensates for the limitation of single-stage components in achieving ultra-low dissolved oxygen levels in one go, ultimately achieving the goal of highly efficient deoxygenation.

[0040] In summary, the three-stage vacuum deoxygenation membrane module 3 forms a progressive treatment process through series connection. By utilizing the synergistic effect of components with the same structure, the dissolved oxygen content in seawater is gradually reduced. This is the key design for achieving the core indicators of this invention: "total deoxygenation efficiency ≥ 99.8% and dissolved oxygen ≤ 50 ppb".

[0041] Example 2 To achieve the above objectives, referring to Figure 5: This embodiment also discloses a treatment method for a membrane-based seawater deoxygenation system used on offshore oil platforms, including the following steps: S1: Seawater enters the precision filtration device 1, and through precision filtration, the turbidity of the seawater is reduced to ≤0.1NTU, the silt density index (SDI) is reduced to ≤3, the total suspended solids concentration is reduced to ≤5mg / L, and the maximum particle diameter is ≤1μm; S2: Seawater enters the microbial sterilization device 2, where ≥99.9% of bacteria, viruses, and microorganisms in the seawater are killed through microbial sterilization treatment; S3: Seawater enters the membrane deoxygenation unit, which includes a three-stage vacuum deoxygenation membrane module 3. After treatment by the membrane deoxygenation unit, the dissolved oxygen content in the seawater is ≤50ppb, and the total deoxygenation efficiency is ≥99.8%. The seawater flow chamber 303 and the gas flow chamber 305 are located on both sides of the deoxygenation membrane 304 and separated by the deoxygenation membrane 304. The operating conditions are as follows: seawater enters the seawater flow chamber 303 on the side of the deoxygenation membrane 304; the dissolved oxygen content of the inlet seawater is 8000~10000ppb; the seawater flow chamber 303 operates under positive pressure. The pressure is 0.15~0.6MPa, the temperature is 5~40℃, the gas flow chamber 305 is in vacuum operation, the pressure is 8~15kPa, the purge gas enters the vacuum gas flow chamber, the oxygen content of the inlet purge gas is ≤0.1%, the deoxygenation membrane 304 is made of hydrophobic microporous membrane material, the pore size of the deoxygenation membrane 304 is 60~90μm, utilizing the water-blocking and air-permeable characteristics of the deoxygenation membrane 304, the dissolved oxygen in the seawater passes through the deoxygenation membrane 304 and enters the gas flow chamber 305 through the seawater flow chamber 303, and the oxygen-enriched purge gas carrying oxygen is discharged from the system through the vacuum device 6.

[0042] This embodiment specifies the core processing steps and parameters. Precision filtration controls turbidity and other indicators to lay the foundation for membrane protection; microbial sterilization ensures that more than 99.9% of microorganisms are removed; three-stage deoxygenation ensures dissolved oxygen ≤50ppb and total efficiency ≥99.8%, directly meeting the reinjection standards of offshore platforms. The steps are clear and operable, ensuring the stability of the treatment effect.

[0043] In a specific example, before S2, the method further includes: setting a seawater softening device 7 at the outlet of the precision filtration device 1 to control the total concentration of calcium and magnesium ions in the seawater to ≤100ppm; before S3, the method further includes: setting an active oxidizing substance removal device 8 at the outlet of the microbial killing device 2 to control the oxidation-reduction potential (ORP) in the seawater to ≤250~350mV.

[0044] This embodiment adds seawater softening and active oxidant removal steps to specifically address the problems of high seawater hardness and oxidant damage to the membrane. It is a supplement and optimization to the core method, further enhancing the system's antifouling capability and ensuring long-term efficient operation.

[0045] In a specific example, the oxygen-enriched purge gas discharged from the vacuum device 6 enters the pressurization device 9, where the pressure is increased to 0.6~0.8MPa. The oxygen-enriched purge gas discharged from the pressurization device 9 then enters the deoxygenation and regeneration device 4. After deoxygenation and regeneration, the dissolved oxygen content in the purge gas is ≤0.01% (volume fraction), and the pressure is 0.4~0.8MPa. The regenerated gas is then regulated in pressure and flow rate before entering the three-stage vacuum deoxygenation membrane assembly 3, ultimately achieving the recycling of the purge gas.

[0046] This embodiment specifies the exact parameters for purge gas circulation (pressurized to 0.6~0.8MPa, oxygen content ≤0.01% after regeneration), making the recycling process quantifiable and easy to control, ensuring that the purge gas quality meets the reuse requirements, and guaranteeing low-cost operation from an operational perspective.

[0047] In a specific example, the deoxygenation regeneration device 4 employs a carbon molecular sieve adsorption device, or a catalytic reaction device including a gas heater, a catalytic reactor, and a gas cooler; When a carbon molecular sieve adsorption device is used, after deoxygenation by carbon molecular sieve adsorption, the purge gas enters the vacuum deoxygenation membrane module 3 after the flow rate is adjusted, which can reduce the purge gas consumption by ≥90%. When a catalytic reaction device is used, the high-pressure oxygen-enriched purge gas entering the deoxygenation regeneration device 4 first enters the gas heater, then enters the catalytic reaction device. After deoxygenation and regeneration, it enters the gas cooler, where the temperature is reduced to 35°C. Then, the purge gas enters the vacuum deoxygenation membrane assembly 3, which can reduce the purge gas consumption by ≥95%. In the catalytic reaction device, the oxygen-enriched purge gas is mixed with associated methane gas from the oilfield and undergoes a catalytic oxidation reaction with an alumina-supported nickel-based catalyst. The gas heater is heated to a temperature of 760~960°C and a pressure of 0.6~0.8MPa. Alternatively, the oxygen-enriched purge gas is mixed with hydrogen and undergoes a catalytic oxidation reaction with an alumina-supported palladium catalyst. The gas heater is heated to a temperature of 150~250°C and a pressure of 0.6~0.8MPa.

[0048] This embodiment refines two implementation methods for the deoxygenation and regeneration device: carbon molecular sieve adsorption reduces purge gas consumption by ≥90%, and catalytic reaction device (reacting with methane or hydrogen) reduces consumption by ≥95%, providing diversified options to adapt to different platform resource conditions (such as whether there is associated gas) and maximizing the reduction of operating costs.

[0049] In a specific example, the precision filtration device 1 in S1 has a filtration accuracy of ≤1μm, and the filter material is one of glass fiber, polysulfone, polyacrylonitrile, silicon dioxide and aluminum oxide; The microbial sterilization device 2 in S2 is equipped with a medium-pressure ultraviolet germicidal lamp 201, with an internal air pressure of 1×10⁻⁶. 5 ~1×10 6Pa, seawater residence time 0.5~1.5 seconds, radiation intensity ≥30mW / cm 2 ; The vacuum deoxidation membrane 3 in S3 is made of one of polytetrafluoroethylene, polyvinylidene fluoride and polypropylene, with an inner diameter of 200~300μm and a wall thickness of 50~100μm. The purge gas in S3 is associated gas from the oilfield. By adjusting the purge gas flow rate, the dissolved oxygen content of the purge gas at the outlet of the gas flow chamber 305 is controlled to be ≤1% (volume fraction). Alternatively, the purging gas in S3 may be nitrogen with a purity of ≥99.9% (volume fraction).

[0050] This embodiment clearly defines the key parameters of each device (such as filtration accuracy ≤1μm, UV lamp parameters, membrane material and size, and purge gas type), providing a clear basis for equipment selection and operation, ensuring stable and controllable system performance, and using associated gas from oilfields to replace nitrogen, further reducing external purchase costs. The associated gas from oilfields is specified to have a dissolved oxygen content of ≤1% (volume fraction) in the outlet gas. Experimental testing and verification have confirmed that this not only meets the gas explosion safety requirements but also takes into account the small scale of purge gas consumption, enhancing the practicality of membrane-based seawater deoxygenation on offshore oil platforms.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A membrane process seawater deoxygenation treatment system for offshore oil platforms, characterized by, The device comprises a precision filtering device, a microorganism killing device, a first vacuum deoxidizing membrane assembly, a second vacuum deoxidizing membrane assembly, a third vacuum deoxidizing membrane assembly, a purge gas storage and supply device, and a vacuum pumping device, wherein the vacuum deoxidizing membrane assembly comprises a seawater flow cavity and a gas flow cavity on both sides of a deoxidizing membrane. The inlet of the precision filtering device is connected with a seawater supply pipeline, the outlet of the precision filtering device is connected with the microorganism killing device, the outlet of the microorganism killing device is connected with the inlet of the seawater flow cavity of the first vacuum deoxidizing membrane assembly, the outlet of the seawater flow cavity of the first vacuum deoxidizing membrane assembly is connected with the inlet of the seawater flow cavity of the second vacuum deoxidizing membrane assembly, the outlet of the seawater flow cavity of the second vacuum deoxidizing membrane assembly is connected with the inlet of the seawater flow cavity of the third vacuum deoxidizing membrane assembly, and the outlet of the seawater flow cavity of the third vacuum deoxidizing membrane assembly is connected with a seawater pipeline after deoxidization. The inlet of the purge gas storage and supply device is connected with a purge gas supply pipeline, the outlets of the purge gas storage and supply device are respectively connected with the inlets of the gas flow cavities of the first, second, and third vacuum deoxidizing membrane assemblies, and the outlets of the gas flow cavities of the first, second, and third vacuum deoxidizing membrane assemblies are directly connected with the vacuum pumping device.

2. The membrane process seawater deoxygenation treatment system for offshore oil platforms according to claim 1, characterized by, The device further comprises a seawater softening device and an active oxidizing substance removal device, the inlet of the seawater softening device is connected with the outlet of the precision filtering device, the outlet of the seawater softening device is connected with the inlet of the microorganism killing device, the seawater softening device adopts one of a nanofiltration membrane filter, a reverse osmosis membrane filter, and an ion exchange resin filter device, and the active oxidizing substance removal device is installed at the outlet of the microorganism killing device and adopts an activated carbon filter or a sodium sulfite dosing device.

3. The membrane process seawater deoxygenation treatment system for offshore oil platforms according to claim 1, characterized by, The device further comprises a deoxidizing regeneration device, which comprises a pressurizing device and a purge gas regeneration device, the inlet of the pressurizing device is connected with the outlet of the vacuum pumping device, the outlet of the pressurizing device is connected with the inlet of the purge gas regeneration device, the outlet of the purge gas regeneration device is connected with the inlet of the purge gas storage and supply device, and oxygen-enriched purge gas can be reused in the deoxidizing membrane assembly after being treated by the pressurizing device and the purge gas regeneration device.

4. The membrane process seawater deoxygenation treatment system for offshore oil platforms according to claim 3, characterized by, The purge gas regeneration device comprises a shell, a deoxidizing particle filling area, an extendable perforated filler pressing plate, an extendable perforated filler supporting rod, and a purge gas uniform distribution area. The lower part of the shell is provided with a powderized deoxidized particle residue emptying port, a purging gas inlet and a deoxidized particle discharge port, the upper part of the shell is provided with a purging gas outlet and a deoxidized particle feeding port, the lower part of the shell is horizontally fixed with a perforated gas-permeable support plate, the perforated gas-permeable support plate has a hole diameter smaller than the minimum particle size of the deoxidized particles, the upper part of the perforated gas-permeable support plate is provided with a deoxidized particle filling area, and the lower part is provided with a purging gas uniform distribution area, the upper part of the deoxidized particle filling area is horizontally provided with a perforated gas-permeable pressing plate, a gas cylinder for controlling the up-down movement of the perforated gas-permeable pressing plate is arranged in the shell, the upper section of the gas cylinder is mounted on the top of the shell and connected with the shell through a hanger column, the lower end of the gas cylinder is fixedly connected with the perforated gas-permeable pressing plate, the perforated gas-permeable pressing plate is connected with the top of the shell through two telescopic support guide devices, the deoxidized particle feeding port is lower than the highest point of the travel of the perforated gas-permeable pressing plate and connected with the deoxidized particle filling area, and the deoxidized particle discharge port is higher than the perforated gas-permeable support plate and connected with the deoxidized particle filling area; the side wall of the deoxidized particle filling area is provided with two or three layers of gas redistribution ring plates; the purging gas uniform distribution area is provided with a plurality of purging gas release devices uniformly distributed along the cross-sectional circumference, one end of the purging gas release device is closed, the other end is connected with each other through a gas collecting box at the center of the cross-sectional circle of the shell, the gas collecting box is connected with the purging gas inlet through a purging gas distribution pipe, and the side wall of the purging gas release device is provided with a gas release nozzle.

5. The membrane process seawater deoxygenation treatment system for offshore oil platforms according to claim 1, characterized by, The precision filtration device comprises a filter core mounting flower plate, a shell, a copper electrode, a sewage cavity, a direct current control power supply, an aluminum electrode, a filter core and a clean water cavity. A seawater inlet of the precision filtration device is arranged on the sewage cavity, and a seawater outlet of the precision filtration device is arranged on the clean water cavity. A medium-pressure ultraviolet germicidal lamp and a transparent quartz baffle are arranged in the microbial killing device and are perpendicular to the water flow direction. The first, second and third vacuum deoxidized membrane assemblies each comprise a seawater inlet, a seawater outlet, a seawater flow cavity, a deoxidized membrane, a gas flow cavity, a purging gas inlet and a purging gas outlet.

6. A treatment method using the membrane method seawater deoxidation treatment system for offshore oil platforms according to any one of claims 1 to 5, characterized by, The method comprises the following steps: S1: seawater enters the precision filtration device, and the turbidity of the seawater is reduced to ≤0.1 NTU, the sludge density index SDI is reduced to ≤3, the total suspended substance concentration is reduced to ≤5 mg / L, and the maximum particle diameter is ≤1 μm through precision filtration; S2: seawater enters the microbial killing device, and ≥99.9% of bacteria, viruses and microorganisms in the seawater are killed through microbial killing treatment; S3: seawater enters a membrane deoxidizing device, the membrane deoxidizing device comprises a three-stage vacuum deoxidizing membrane assembly, after the seawater is treated by the membrane deoxidizing device, the content of dissolved oxygen in the seawater is less than or equal to 50 ppb, and the total deoxidizing efficiency is greater than or equal to 99.8%; The seawater flow cavity and the gas flow cavity are located on both sides of the deoxidizing membrane and are separated by the deoxidizing membrane; the working conditions are as follows: seawater enters the seawater flow cavity on one side of the deoxidizing membrane, the dissolved oxygen content of the inlet seawater is 8000-10000 ppb, the seawater flow cavity is operated under positive pressure, the pressure is 0.15-0.6 MPa, the temperature is 5-40 DEG C, the gas flow cavity is operated under vacuum, the pressure is 8-15 kPa, the sweep gas enters the vacuum gas flow cavity, the oxygen content of the inlet sweep gas is less than or equal to 0.1%, the deoxidizing membrane is made of a hydrophobic microporous membrane material, the pore size of the deoxidizing membrane is 60-90 mu m, the dissolved oxygen in the seawater penetrates the deoxidizing membrane and enters the gas flow cavity from the seawater flow cavity by utilizing the water-blocking and gas-permeating characteristics of the deoxidizing membrane, and the oxygen-enriched sweep gas carrying oxygen is discharged from the system by the vacuum pumping device.

7. The membrane process for seawater deoxygenation treatment for offshore oil platforms according to claim 6, characterized by, The S2 further comprises a seawater softening device arranged at the outlet of the precision filtering device to control the total concentration of calcium and magnesium ions in the seawater to be less than or equal to 100 ppm; and the S3 further comprises an active oxidizing substance removal device arranged at the outlet of the microorganism killing device to control the oxidation-reduction potential (ORP) in the seawater to be less than or equal to 250-350 mV.

8. The membrane process for seawater deoxygenation treatment for offshore oil platforms according to claim 6, characterized by, The oxygen-enriched sweep gas discharged from the vacuum pumping device enters a pressure boosting device, the pressure is increased to 0.6-0.8 MPa, the oxygen-enriched sweep gas discharged from the pressure boosting device enters a deoxidizing regeneration device, the dissolved oxygen content in the sweep gas is less than or equal to 0.1% after the deoxidizing regeneration treatment, the pressure is 0.4-0.8 MPa, and the regenerated gas enters the three-stage vacuum deoxidizing membrane assembly after being adjusted in pressure and flow rate, so that the recycling of the sweep gas is finally realized.

9. The membrane process for seawater deoxygenation treatment for offshore oil platforms according to claim 8, characterized by, The deoxidizing regeneration device adopts a carbon molecular sieve adsorption device or a catalytic reaction device comprising a gas heater, a catalytic reactor and a gas cooler; When the carbon molecular sieve adsorption device is adopted, after the deoxidizing adsorption by the carbon molecular sieve, the sweep gas enters the vacuum deoxidizing membrane assembly after being adjusted in flow rate, so that the sweep gas consumption can be reduced by greater than or equal to 90%; When the catalytic reaction device is adopted, the high-pressure oxygen-enriched sweep gas entering the deoxidizing regeneration device first enters the gas heater, then enters the catalytic reaction device, is treated by the deoxidizing regeneration, enters the gas cooler, the temperature is reduced to 35 DEG C, and then the sweep gas enters the vacuum deoxidizing membrane assembly, so that the sweep gas consumption can be reduced by greater than or equal to 95%; wherein, in the catalytic reaction device, the oxygen-enriched sweep gas is mixed with the oilfield associated methane gas and is subjected to catalytic oxidation reaction by the alumina-supported nickel-based catalyst, the heating temperature of the gas heater is 760-960 DEG C, and the pressure is 0.6-0.8 MPa; or, the oxygen-enriched sweep gas is mixed with hydrogen and is subjected to catalytic oxidation reaction by the alumina-supported palladium catalyst, the heating temperature of the gas heater is 150-250 DEG C, and the pressure is 0.6-0.8 MPa.

10. The membrane process for seawater deoxygenation treatment for offshore oil platforms according to claim 6, characterized by, The precision filtering device in the S1 has a filtering precision of less than or equal to 1 mu m, and the filtering material is one of glass fiber, polysulfone, polyacrylonitrile, silicon oxide and aluminum oxide; The microbial sterilization device in S2 is equipped with a medium-pressure ultraviolet germicidal lamp, with an internal air pressure of 1×10⁻⁶. 5 ~1×10 6 Pa, seawater residence time 0.5~1.5 seconds, radiation intensity ≥30mW / cm 2 ; The vacuum deoxidizing film material in S3 is one of polytetrafluoroethylene, polyvinylidene fluoride and polypropylene, the film inner diameter is 200-300 μm, and the wall thickness is 50-100 μm; The purge gas in S3 is oilfield associated gas, and by adjusting the purge gas flow, the dissolved oxygen content of the purge gas at the outlet of the gas flow cavity is controlled to be ≤1%; Or the purge gas in S3 is nitrogen with a purity of ≥99.9%.

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