A device and method for softening treatment of high-temperature oilfield wastewater

Abstract

This invention discloses a softening treatment device and method for high-temperature oilfield wastewater, relating to the field of wastewater treatment technology. Oilfield wastewater enters a pre-desorption tank for impurity removal. The barium-strontium adsorption tank contains, from top to bottom, a fine quartz sand layer, a chelating resin layer, and a coarse quartz sand layer. The silicate pre-desorption tank contains an acid-base regulator, a dispersant, and a magnesium oxide suspension. The carbonate softening tank contains a dispersant, a coagulant aid, a soda ash solution, and a chelating agent. The stabilizing tank contains, from top to bottom, a modified activated carbon layer and an exchange resin layer. This invention uses the pre-desorption tank to initially separate oil, suspended solids, and corrosion products. A specialized chelating resin selectively adsorbs barium-strontium ions. In the silicate pre-desorption tank, pH is precisely controlled and magnesium oxide is added to directionally generate settleable magnesium silicate flocs. In the carbonate softening tank, crystal form control and coagulation aid work synergistically to promote the precipitation of calcium and magnesium in the form of large calcite particles.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a softening treatment device and method for wastewater from high-temperature oilfields. Background Technology

[0002] During oil extraction, especially in thermal oil recovery operations, a large amount of high-temperature produced water is generated. This type of oilfield wastewater is typically characterized by high temperature, high mineralization, and high hardness. It contains high concentrations of scale-forming ions such as calcium ions, magnesium ions, bicarbonate ions, and sulfate ions. As the temperature rises, bicarbonate in the water easily decomposes to form carbonate ions, which then combine with calcium and magnesium ions to form insoluble precipitates such as calcium carbonate and magnesium carbonate. At the same time, high temperature also significantly accelerates the precipitation process of slightly soluble salts such as calcium sulfate. These inorganic scale deposits in pipelines, heat exchangers, water injection pumps, and formation pores, which not only reduce the heat transfer efficiency of equipment and increase flow resistance, but may also cause serious blockages, affecting the normal production and operation of the oilfield. In addition, conventional water treatment agents are prone to thermal decomposition or failure under high-temperature environments, and traditional softening processes are difficult to apply directly. This makes the treatment of high-temperature oilfield wastewater a technical challenge in oilfield water management. With increasingly stringent environmental regulations and rising demands for water resource recycling, efficient, stable, and economical softening treatment of high-temperature produced water has become an important link in ensuring the sustainable development of oilfields.

[0003] In practical applications, existing technologies often rely on single chemical softening or ion exchange resin treatments, lacking differentiated identification and treatment strategies for various scaling ions in oilfield wastewater, such as calcium, magnesium, barium, strontium, and activated silica. Due to the significant differences in scaling mechanisms, reaction conditions, and precipitation characteristics of different ions, the general use of uniform agents or fixed processes easily leads to the cross-precipitation of multiple types of scale, such as carbonates, sulfates, and silicates, forming dense, hard, and difficult-to-remove composite scale. At the same time, traditional sedimentation processes mainly rely on natural gravity sedimentation, resulting in small, loose flocs with slow sedimentation rates, leading to high turbidity and large fluctuations in suspended solids content in the effluent, which can easily cause clogging and contamination in subsequent filtration processes. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a softening treatment device and method for high-temperature oilfield wastewater.

[0005] The technical solution adopted to solve the above-mentioned technical problems is as follows: oilfield wastewater enters a pre-desorption and impurity removal tank for impurity and pollution removal. A high-temperature demulsifier, corrosion inhibitor, and biological stripping agent are added sequentially to the pre-desorption and impurity removal tank. The side wall output end of the pre-desorption and impurity removal tank is connected to the bottom inlet end of a barium-strontium adsorption tank via a first conveying pipe. The barium-strontium adsorption tank is equipped with a fixed-bed adsorption structure, which consists of a fine quartz sand layer, a chelating resin layer, and a coarse quartz sand layer arranged sequentially from top to bottom. The top outlet end of the barium-strontium adsorption tank is connected to a silicate... The top inlet ends of the pre-removal tanks are interconnected. Acid-base regulators, dispersants, and magnesium oxide suspensions are added to the silicate pre-removal tank. The side wall outlet end of the silicate pre-removal tank is interconnected with the top inlet end of the carbonate softening tank through a third conveying pipe. Dispersants, coagulants, soda ash solution, and chelating agents are added to the carbonate softening tank. The side wall outlet end of the carbonate softening tank enters the interior of the stabilizing tank through a fourth conveying pipe. The interior of the stabilizing tank is arranged from top to bottom with a modified activated carbon layer and an exchange resin layer. A discharge pipe interconnected with the interior of the stabilizing tank is provided at the bottom of the stabilizing tank.

[0006] Furthermore, the pre-desorption and impurity removal tank is equipped with, from top to bottom, interconnected inclined plate oil removal cylinders, an aeration and mixing zone, and a conical sludge hopper. A wastewater inlet pipe, connected to the inclined plate oil removal cylinder, is located at the top of the pre-desorption and impurity removal tank. Oilfield wastewater enters the pre-desorption and impurity removal tank through this inlet pipe. A demulsifier pipe, connected to the inclined plate oil removal cylinder, is located on the side wall of the pre-desorption and impurity removal tank. A corrosion inhibitor pipe, also connected to the demulsifier pipe, is located on the demulsifier pipe. High-temperature demulsifier enters the pre-desorption and impurity removal tank through the demulsifier pipe, and the corrosion inhibitor enters the pre-desorption and impurity removal tank sequentially through the corrosion inhibitor pipe and the demulsifier pipe. The pre-desorption and impurity removal process... The side wall of the waste tank is equipped with a stripping agent pipe that is connected to the aeration and mixing zone. The biological stripping agent enters the interior of the pre-desorption waste removal tank through the stripping agent pipe. The inner side wall of the aeration and mixing zone is equipped with a first annular aeration pipe. The side wall of the pre-desorption waste removal tank is equipped with a first air inlet pipe that is connected to the first annular aeration pipe. The first annular aeration pipe is uniformly machined with multiple aeration holes along the circumference. The side wall of the pre-desorption waste removal tank is equipped with a first coagulant aid pipe that is connected to the conical sludge hopper. The coagulant aid enters the interior of the pre-desorption waste removal tank through the first coagulant aid pipe. The bottom of the pre-desorption waste removal tank is equipped with a first sludge discharge pipe that is connected to the conical sludge hopper.

[0007] Furthermore, the top of the silicate pre-removal tank is equipped with a pH pipe, a first dispersant pipe, and a magnesium oxide suspension pipe that are interconnected with its interior. The acid-base adjuster enters the silicate pre-removal tank through the pH pipe, the dispersant enters the silicate pre-removal tank through the first dispersant pipe, and the magnesium oxide suspension enters the silicate pre-removal tank through the magnesium oxide suspension pipe. The bottom opening of the silicate pre-removal tank is equipped with a second drain pipe that is interconnected with its interior.

[0008] Furthermore, a first motor is installed on the top of the silicate pre-removal tank, and the output shaft of the first motor is fixedly connected to a gear. A scraper for scraping sludge from the inner wall of the silicate pre-removal tank is rotatably installed inside the silicate pre-removal tank. Multiple stirring rods are installed on the scraper, and a gear ring that meshes with the gear is installed on the top of the scraper.

[0009] Furthermore, the top of the carbonate softening tank is equipped with a second dispersant pipe, a second coagulant aid pipe, a chelating agent pipe, and a soda ash pipe that are interconnected with the interior. The dispersant enters the interior of the carbonate softening tank through the second dispersant pipe, the coagulant aid enters the interior of the carbonate softening tank through the second coagulant aid pipe, the soda ash solution enters the interior of the carbonate softening tank through the soda ash pipe, and the chelating agent enters the interior of the carbonate softening tank through the chelating agent pipe.

[0010] Furthermore, the carbonate softening tank is provided with interconnected mixing reaction zone, flocculation maturation zone and high-efficiency settling zone from top to bottom. The mixing reaction zone is provided with a central guide tube inside the carbonate softening tank. The flocculation maturation zone is provided with a sleeve inside the carbonate softening tank, and an upper filter screen is provided at the top of the sleeve. The high-efficiency settling zone is provided with a conical sludge sleeve at the bottom of the sleeve, which is interconnected with the upper filter screen. A lower filter screen is provided at the top of the conical sludge sleeve and connected to the bottom of the sleeve. The lower filter screen is located below the upper filter screen.

[0011] Furthermore, a second motor is installed at the top of the carbonate softening tank. The output shaft of the second motor is fixedly connected to a rotating rod. Multiple blades are installed on the rotating rod inside the central guide tube. A second annular aeration pipe is installed on the inner wall of the central guide tube. Multiple aeration holes are arranged along the circumference of the second annular aeration pipe. A second air inlet pipe is installed on the carbonate softening tank and communicates with the second annular aeration pipe. Multiple mixing rods are installed on the rotating rod inside the flocculation maturation zone. An upper limit block and a lower limit block are installed on the rotating rod. An electromagnet is installed at the bottom of the carbonate softening tank and located outside the conical sludge sleeve. A push plate is slidably connected to the rotating rod in the vertical direction. An iron block magnetically connected to the electromagnet is enclosed inside the push plate. The push plate is located between the upper limit block and the lower limit block. A bracket is installed on the rotating rod. A scraper is installed on the bracket to scrape the material on the inner wall of the conical sludge sleeve. A third drain pipe communicating with the inside of the conical sludge sleeve is installed at the bottom outlet end of the carbonate softening tank.

[0012] A method for softening wastewater from high-temperature oilfields includes the following steps: S1 is used for cooling pretreatment of produced water from high-temperature, high-silicon oilfields. S2. High-temperature oilfield wastewater enters the pre-desorption and impurity removal tank through the wastewater inlet pipe. High-temperature demulsifier enters the pre-desorption and impurity removal tank through the demulsifier pipe. Corrosion inhibitor enters the pre-desorption and impurity removal tank sequentially through the corrosion inhibitor pipe and the demulsifier pipe. The high-temperature demulsifier breaks down the emulsified oil interface film of the high-temperature oilfield wastewater, causing oil droplets to coalesce. The corrosion inhibitor forms a protective film on the inner wall of the pre-desorption and impurity removal tank to prevent corrosion. The biological stripper enters the pre-desorption and impurity removal tank through the stripper pipe. The biological stripper strips the biofilm in the high-temperature oilfield wastewater. The coagulant enters the pre-desorption and impurity removal tank through the first coagulant aid pipe. The coagulant causes suspended particles and corrosion products to coalesce into flocs, which settle in the conical sludge hopper. The settled sludge is discharged through the first sewage pipe. The pretreated high-temperature oilfield wastewater enters the barium strontium adsorption tank through the first conveying pipe. S3, the wastewater inside the barium and strontium adsorption tank passes sequentially through a coarse quartz sand layer, a chelating resin layer, and a fine quartz sand layer. The coarse quartz sand layer achieves uniform water distribution, the chelating resin layer adsorbs barium and strontium in the wastewater, and blocks the formation of barium sulfate and strontium sulfate scale in high-temperature oilfield wastewater. The fine quartz sand layer filters resin debris in the wastewater. The wastewater after the removal of barium and strontium enters the silicate pre-removal tank through the second conveying pipe. S4, the acid-base regulator enters the silicate pre-removal tank through the pH pipe, the dispersant enters the silicate pre-removal tank through the first dispersant pipe, and the magnesium oxide suspension enters the silicate pre-removal tank through the magnesium oxide suspension pipe. The wastewater, acid-base regulator, dispersant and magnesium oxide suspension are thoroughly stirred. The acid-base regulator adjusts the pH of the wastewater to 8.5-9.0. The magnesium ions in the magnesium oxide suspension cause the silicate ions in the wastewater to form magnesium silicate flocs. The dispersant prevents the magnesium silicate flocs in the wastewater from agglomerating. The settled magnesium silicate flows out through the second drain pipe. The desiliconized wastewater enters the carbonate softening tank through the third conveying pipe. S5. The dispersant enters the carbonate softening tank through the second dispersant pipe, the coagulant aid enters the carbonate softening tank through the second coagulant aid pipe, the soda ash solution enters the carbonate softening tank through the soda ash pipe, and the chelating agent enters the carbonate softening tank through the chelating agent pipe. The carbonate ions in the soda ash solution react with the calcium ions in the wastewater to form calcium carbonate precipitate. The chelating agent guides the ions to form large-particle crystals. The coagulant aid and dispersant are used to enhance the sedimentation effect of calcium carbonate. The output shaft of the second motor drives the rotating rod to rotate. Multiple blades on the rotating rod stir at high speed inside the central guide tube, thoroughly shearing and mixing the wastewater with dispersant, coagulant aid, soda ash solution, and chelating agent. Multiple mixing rods on the rotating rod rotate to thoroughly stir the mixed solution. The upper and lower filter screens intercept the fine particles that have not settled, accelerating the settling of the sediment inside the conical sludge sleeve. The rotating scraper on the rotating rod scrapes away impurities from the inner wall of the conical sludge sleeve. The sediment is discharged through the third drain pipe, and the purified wastewater flows into the stabilization tank through the fourth conveying pipe. S6, the water inside the stabilizing tank passes sequentially through a modified activated carbon layer and an exchange resin layer. The modified activated carbon layer captures residual active silicon, trace organic matter and colloidal particles in the water, while the exchange resin layer removes residual divalent metal ions such as calcium and magnesium, thus completing the softening treatment of the wastewater.

[0013] Furthermore, the method for fully stirring the wastewater, acid-base regulator, dispersant, and magnesium oxide suspension in S4 is as follows: the output shaft of the first motor drives the gear to rotate, the gear drives the gear ring to rotate through meshing with the gear ring, the gear ring drives the scraper to rotate, the scraper scrapes off impurities on the inner side wall of the silicate pre-removal tank, and multiple stirring rods on the scraper rotate to fully stir the wastewater, acid-base regulator, dispersant, and magnesium oxide suspension.

[0014] Furthermore, the method for accelerating the settling of sediment inside the conical sludge sleeve in S5 is as follows: through the magnetic connection between the electromagnet and the iron block inside the pusher plate, the iron block drives the pusher plate to slide vertically on the rotating rod. The pusher plate moves between the upper limit block and the lower limit block. When the pusher plate moves downward, it squeezes the sewage inside the conical sludge sleeve. After being squeezed, the sewage flows back upward from the lower filter screen. The lower filter screen filters the impurities in the water, and the impurities attached to the lower filter screen will settle downward, shortening the time consumed by natural settling. When the pusher plate moves upward, the sewage flows downward on the upper and lower filter screens, causing the impurities on the surface of the upper and lower filter screens to fall off.

[0015] The beneficial effects of the present invention are as follows: (1) The present invention introduces high-temperature oilfield wastewater into a pre-desorption tank, a barium strontium adsorption tank, a silicate pre-desorption tank, a carbonate softening tank and a stabilizing tank in sequence. The pre-desorption tank initially separates oil, suspended solids and corrosion products. A special chelating resin selectively adsorbs barium strontium ions to block the formation of sulfate scale from the source. In the silicate pre-desorption tank, the pH is precisely controlled and magnesium oxide is added to directionally generate sedimentable magnesium silicate flocs. In the carbonate softening tank, through crystal form control and coagulation assistance, calcium and magnesium are precipitated in the form of large calcite particles. The process is purified step by step, avoiding cross-interference and co-precipitation of ions and avoiding the problem of cross-precipitation of multiple types of scale caused by traditional single softening method. Different special agents are added to each tank and the large-particle, high-density crystals are guided to be generated instead of colloidal precipitates through zoned stirring. The reaction rate and sedimentation performance are significantly improved, and the problems of difficult removal of complex hard scale, waste of agents and unstable system operation are fundamentally solved.

[0016] (2) The present invention integrates a central guide tube, multi-stage stirring, inclined filter screen and magnetically driven push plate in the carbonate softening tank, realizing three functions: strong mixing, weak flocculation and fast settling. High-speed stirring ensures that the reagent is fully dispersed and crystal nuclei are generated. Low shear maturation promotes the growth of flocs. The inclined upper and lower filter screens intercept fine particles and use gravity for self-cleaning. The magnetically driven push plate accelerates the compaction and settling of sludge by periodically squeezing the water flow, and backwashes the filter screen surface to prevent clogging. With the help of the conical sludge hopper and sludge scraping mechanism, the sludge can be discharged in time, avoiding sludge back-mixing, greatly improving the solid-liquid separation efficiency, effectively ensuring the clarity of the effluent and preventing subsequent clogging, and significantly improving the reliability and treatment efficiency of the system's continuous operation.

[0017] (3) The present invention sets up a double layer of modified activated carbon and high temperature resistant cation exchange resin inside the stabilizing tank. The former efficiently adsorbs residual silicon and organic matter, while the latter deeply removes trace hardness ions, forming a double water quality insurance. The two work together to complete the deep removal of residual silicon, organic matter and hardness ions, ensuring that the effluent water quality is stable and meets the standards for reinjection or boiler feedwater. The packing layer is equipped with an anti-loss grid and a uniform water distribution structure to prevent channeling and penetration, ensuring long-term purification effect. The whole system thus realizes a closed loop from coarse treatment to fine stabilization, providing a reliable technical guarantee for the resource utilization of high temperature and high mineralization oilfield wastewater. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of one embodiment of the softening treatment device for high-temperature oilfield wastewater according to the present invention.

[0019] Figure 2 yes Figure 1 A schematic diagram of the internal structure.

[0020] Figure 3 This is a schematic diagram of the internal structure of the pre-desorption and impurity removal tank.

[0021] Figure 4 This is a schematic diagram of the internal structure of a barium-strontium adsorption tank.

[0022] Figure 5 This is a schematic diagram of the silicate pre-removal tank.

[0023] Figure 6 This is a schematic diagram of the internal structure of the silicate pre-removal tank.

[0024] Figure 7 This is a schematic diagram of the stirring rod and scraper.

[0025] Figure 8 This is a schematic diagram of the structure of a carbonate softening tank.

[0026] Figure 9 This is a schematic diagram of the internal structure of a carbonate softening tank.

[0027] Figure 10 This is a schematic diagram of the structure of the conical sludge sleeve, lower filter screen, sleeve, and upper filter screen.

[0028] Figure 11 This is a schematic diagram of the internal structure of the stabilizing tank.

[0029] Reference numerals: 1. Pre-desorption and impurity removal tank; 101. Wastewater inlet pipe; 102. Inclined plate oil removal cylinder; 103. Corrosion inhibitor pipe; 104. Demulsifier pipe; 105. First annular aeration pipe; 106. Stripping agent pipe; 107. First air inlet pipe; 108. First coagulant aid pipe; 109. Conical sludge hopper; 110. First discharge pipe; 111. Aeration and mixing zone; 2. First conveying pipe; 3. Barium-strontium adsorption tank; 301. Fine quartz sand layer; 302. Chelating resin layer; 303. Coarse quartz sand layer; 4. Second conveying pipe; 5. Silicate pre-removal tank; 501. First motor; 502. pH pipe; 503. First dispersant pipe; 504. Magnesium oxide suspension pipe; 505. Gear; 506. Gear ring; 507. Second discharge pipe; 508. Stirring rod; 509. 6. Scraper; 7. Third conveying pipe; 8. Carbonate softening tank; 9. Second dispersant pipe; 10. Second coagulant aid pipe; 11. Chelating agent pipe; 12. Soda ash pipe; 13. Second motor; 14. Rotating rod; 15. Central guide tube; 16. Blade; 17. Push plate; 18. Iron block; 19. Lower limit block; 20. Electromagnet; 10. Third drain pipe; 11. Support; 22. Conical sludge sleeve; 33. Sludge scraper; 44. Lower filter screen; 55. Sleeve; 66. Upper filter screen; 77. Mixing rod; 88. Second air inlet pipe; 99. Second annular aeration pipe; 10. Upper limit block; 11. Fourth conveying pipe; 12. Stabilizer; 13. Modified activated carbon layer; 14. Exchange resin layer; 15. Discharge pipe. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] like Figures 1 to 2 , Figure 4 , Figure 11 As shown, the softening treatment device for high-temperature oilfield wastewater in this embodiment is composed of a pre-desorption and impurity removal tank 1, a first conveying pipe 2, a barium strontium adsorption tank 3, a second conveying pipe 4, a silicate pre-removal tank 5, a third conveying pipe 6, a carbonate softening tank 7, a fourth conveying pipe 8, and a stabilizing tank 9 connected together.

[0032] Oilfield wastewater enters pre-desorption and impurity removal tank 1 for impurity and contamination removal. High-temperature demulsifier, corrosion inhibitor, and biological stripping agent are added sequentially to pre-desorption and impurity removal tank 1. The high-temperature demulsifier's main component is a polyoxyethylene-polyoxypropylene block copolymer, suitable for high-temperature environments above 120℃. The corrosion inhibitor's main component is an imidazoline quaternary ammonium salt compound, which can form a dense adsorption film on the surface of 316L stainless steel and carbon steel, effectively inhibiting H2S, CO2, and Cl-. - Corrosion caused by this. The active ingredient of the bio-stripping agent is a compound of quaternary ammonium salt cationic surfactant and organic acid, which can effectively penetrate and strip the biofilm formed by sulfate-reducing bacteria (SRB) without affecting the subsequent resin performance.

[0033] The side wall output end of the pre-desorption and impurity removal tank 1 is connected to the bottom inlet end of the barium-strontium adsorption tank 3 via the first conveying pipe 2. The barium-strontium adsorption tank 3 is made of duplex stainless steel 2205. The barium-strontium adsorption tank 3 has a fixed-bed adsorption structure inside, which consists of, from top to bottom, a fine quartz sand layer 301, a chelating resin layer 302, and a coarse quartz sand layer 303. The chelating resin layer 302 uses an aminophosphonic acid type special resin that is resistant to temperatures up to 120℃. The chelating resin layer 302 selectively adsorbs barium and strontium in wastewater, blocking the formation of barium sulfate and strontium sulfate scale at the source. This aminophosphonic acid type chelating resin reacts with Ca... 2+ Mg 2+ It maintains excellent selectivity even when coexisting and will not be poisoned or deactivated by the coagulant or corrosion inhibitor added in the previous stage.

[0034] The top outlet of the barium-strontium adsorption tank 3 is connected to the top inlet of the silicate pre-removal tank 5 via the second conveying pipe 4. The silicate pre-removal tank 5 is made of 316L stainless steel to ensure that the effluent water quality is consistently up to standard. Acid-base regulator, dispersant, and magnesium oxide suspension are added to the silicate pre-removal tank 5. The acid-base regulator is usually an industrial-grade NaOH solution with a concentration of 10-30%, or food-grade citric acid (for fine-tuning) to ensure that no additional hardness ions are introduced. The magnesium oxide suspension is prepared as a 5-10% slurry using lightly calcined MgO (purity ≥98%) with a particle size D50≈2-5 μm. It has high reactivity and does not introduce chloride ions. The main components of the dispersant are sodium polyacrylate (PAAS) or polymaleic acid (PMA) with a molecular weight of 5000-10000 Da, which can effectively stabilize the magnesium silicate colloid and prevent clogging of the subsequent resin bed.

[0035] The outlet end of the side wall of the silicate pre-removal tank 5 is connected to the top inlet end of the carbonate softening tank 7 via a third conveying pipe 6. Dispersant, coagulant aid, soda ash solution, and chelating agent are added to the carbonate softening tank 7. The soda ash solution is sodium carbonate with a concentration of 10-15%, used to precipitate Ca. 2+The chelating agent can be tetrasodium ethylenediaminetetraacetate or trisodium methylglycine diacetate. The latter is biodegradable, stable at high temperatures, and can guide the directional growth of CaCO3 crystals into dense calcite rather than loose aragonite, improving settling performance. It also reacts with residual Mg from the previous silicate treatment. 2+ No interference. The coagulant is also a high molecular weight CPAM (such as Superfloc). ® C444), the dispersant can be the same as Sokalan. ® CP5 and the two have a synergistic effect. CPAM bridges the flocs, and the dispersant prevents excessive aggregation, ensuring that the flocs are dense and easy to settle.

[0036] The carbonate softening tank 7's side wall outlet enters the stabilizing tank 9 through the fourth conveying pipe 8. The stabilizing tank 9 is made of 316L stainless steel. Inside the stabilizing tank 9, from top to bottom, there are a modified activated carbon layer 901 and an exchange resin layer 902. The modified activated carbon layer 901 is activated at high temperature and modified with surface functional groups, giving it strong adsorption capacity. It can effectively capture residual active silicon, trace organic matter, and colloidal particles in the water. This modified activated carbon is activated with phosphoric acid or ZnCl2 and loaded with a small amount of Fe. 3+ / Al 3+ The oxide enhances the affinity for silicic acid and humic acid, and is temperature resistant up to 120℃. The 902 cation exchange resin layer is a high-temperature resistant, strongly acidic cation exchange resin specifically designed to adsorb residual divalent metal ions such as calcium and magnesium that were not completely removed in the first four stages, achieving deep softening. This resin is a sulfonated styrene-divinylbenzene copolymer, temperature resistant up to 120℃, with an exchange capacity ≥1.8 eq / L, and is effective against Ca... 2+ Mg 2+ It exhibits high selectivity and is unaffected by residual trace amounts of dispersant or chelating agent from the upstream stage (due to their extremely low concentration). The bottom of the stabilizing tank 9 is equipped with a discharge pipe 903 that communicates with its interior.

[0037] like Figure 3 As shown, the pre-desorption and impurity removal tank 1 includes a wastewater inlet pipe 101, an inclined plate oil removal cylinder 102, a corrosion inhibitor pipe 103, a demulsifier pipe 104, a first annular aeration pipe 105, a stripping agent pipe 106, a first air inlet pipe 107, a first coagulant aid pipe 108, a conical sludge hopper 109, a first sewage discharge pipe 110, and an aeration and mixing zone 111.

[0038] The tank body of the pre-desorption and impurity removal tank 1 is made of 316L stainless steel. The inner wall of the pre-desorption and impurity removal tank 1 is coated with a PTFE anti-corrosion layer. The pre-desorption and impurity removal tank 1 is arranged from top to bottom with interconnected inclined plate oil removal cylinder 102, aeration and stirring zone 111, and conical sludge hopper 109. The inclined plate oil removal cylinder 102 is made of high temperature resistant modified PP board with an inclination angle of 60° to achieve the separation of oil droplets that have coalesced and floated upward. The tip of the conical sludge hopper 109 is located at the bottom, and the circular surface of the conical sludge hopper 109 is located at the top.

[0039] The pre-desorption and impurity removal tank 1 is equipped with a wastewater inlet pipe 101 at the top, which is connected to the inclined plate oil removal cylinder 102. Oilfield wastewater enters the pre-desorption and impurity removal tank 1 through the wastewater inlet pipe 101. The side wall of the pre-desorption and impurity removal tank 1 is equipped with a demulsifier pipe 104, which is connected to the inclined plate oil removal cylinder 102. A corrosion inhibitor pipe 103 is connected to the demulsifier pipe 104. High-temperature demulsifier enters the pre-desorption and impurity removal tank 1 through the demulsifier pipe 104. The corrosion inhibitor enters the pre-desorption and impurity removal tank 1 through the corrosion inhibitor pipe 103 and the demulsifier pipe 104 in sequence. The side wall of the pre-desorption and impurity removal tank 1 is equipped with a stripping agent pipe 106, which is connected to the aeration and stirring zone 111. Biological stripping agent enters the pre-desorption and impurity removal tank 1 through the stripping agent pipe 106. Aeration and stirring... A first annular aeration pipe 105 is provided on the inner wall of the mixing zone 111. A first air inlet pipe 107, which is connected to the first annular aeration pipe 105, is provided on the side wall of the pre-desorption and impurity removal tank 1. The first annular aeration pipe 105 is uniformly machined with multiple aeration holes along the circumference. Compressed air delivered by the first air inlet pipe 107 is introduced into the sewage in the form of microbubbles through the multiple aeration holes on the first annular aeration pipe 105 to achieve aeration and mixing, so that the agent and sewage are fully mixed. A first coagulant aid pipe 108, which is connected to the conical sludge hopper 109, is provided on the side wall of the pre-desorption and impurity removal tank 1. The coagulant aid is high molecular weight cationic polyacrylamide (CPAM) with a molecular weight ≥10, which enters the interior of the pre-desorption and impurity removal tank 1 through the first coagulant aid pipe 108. 7 Da, with a charge density of 30-50%, is suitable for high-mineralization, high-temperature water bodies. It has no chemical conflict with the aforementioned demulsifiers and corrosion inhibitors. The bottom of the pre-desorption and impurity removal tank 1 is equipped with a first sewage pipe 110 that is interconnected with the conical sludge hopper 109.

[0040] like Figures 5 to 7 As shown, the silicate pre-removal tank 5 includes a first motor 501, a pH pipe 502, a first dispersant pipe 503, a magnesium oxide suspension pipe 504, a gear 505, a gear ring 506, a second drain pipe 507, a stirring rod 508, and a scraper 509.

[0041] The top of the silicate pre-removal tank 5 is equipped with a pH pipe 502, a first dispersant pipe 503, and a magnesium oxide suspension pipe 504, which are interconnected with the tank's interior. The acid-base adjuster enters the silicate pre-removal tank 5 through the pH pipe 502, the dispersant enters the tank through the first dispersant pipe 503, and the magnesium oxide suspension enters the tank through the magnesium oxide suspension pipe 504. The bottom opening of the silicate pre-removal tank 5 is equipped with a second drain pipe 507, which is interconnected with the tank's interior.

[0042] A first motor 501 is installed on the top of the silicate pre-removal tank 5. The output shaft of the first motor 501 is fixedly connected to the gear 505. A scraper 509 for scraping sludge from the inner wall of the silicate pre-removal tank 5 is rotatably installed inside the silicate pre-removal tank 5. Multiple stirring rods 508 are installed on the scraper 509. A gear ring 506 that meshes with the gear 505 is installed on the top of the scraper 509.

[0043] like Figures 8 to 10 As shown, the carbonate softening tank 7 includes a second dispersant pipe 701, a second coagulant aid pipe 702, a chelating agent pipe 703, a soda ash pipe 704, a second motor 705, a rotating rod 706, a central guide tube 707, a blade 708, a push plate 709, an iron block 710, a lower limit block 711, an electromagnet 712, a third drain pipe 713, a support 714, a conical sludge sleeve 715, a scraper 716, a lower filter screen 717, a sleeve 718, an upper filter screen 719, a mixing rod 720, a second air inlet pipe 721, a second annular aeration pipe 722, and an upper limit block 723.

[0044] The carbonate softening tank 7 is made of Hastelloy C-276, which is resistant to strong alkali and high temperature corrosion. The top of the carbonate softening tank 7 is equipped with a second dispersant pipe 701, a second coagulant aid pipe 702, a chelating agent pipe 703, and a soda ash pipe 704, which are interconnected with the interior. The dispersant enters the interior of the carbonate softening tank 7 through the second dispersant pipe 701, the coagulant aid enters the interior of the carbonate softening tank 7 through the second coagulant aid pipe 702, the soda ash solution enters the interior of the carbonate softening tank 7 through the soda ash pipe 704, and the chelating agent enters the interior of the carbonate softening tank 7 through the chelating agent pipe 703.

[0045] The carbonate softening tank 7 contains, from top to bottom, interconnected mixing reaction zone, flocculation maturation zone, and high-efficiency settling zone. The mixing reaction zone is comprised of a central guide tube 707. The flocculation maturation zone is comprised of a sleeve 718 made of non-magnetic Hastelloy alloy, with its inner wall polished to reduce friction and ensure the reliability of the push plate 709's long-term reciprocating motion. An upper filter screen 719 is located at the top of the sleeve 718. The high-efficiency settling zone is comprised of a conical sludge sleeve 715 interconnected with the bottom of the sleeve 718. A lower filter screen 717, connected to the bottom of the sleeve 718, is located at the top of the conical sludge sleeve 715 and positioned below the upper filter screen 719. Both the upper and lower filters 719 are made of high-temperature resistant materials.

[0046] A second motor 705 is installed at the top of the carbonate softening tank 7. The output shaft of the second motor 705 is fixedly connected to a rotating rod 706. Multiple blades 708 are installed on the rotating rod 706 inside a central guide tube 707. A second annular aeration pipe 722 is installed on the inner wall of the central guide tube 707. Multiple aeration holes are arranged along the circumference of the second annular aeration pipe 722. A second air inlet pipe 721, which communicates with the second annular aeration pipe 722, is installed on the carbonate softening tank 7. The rotating rod... Multiple mixing rods 720 are installed on the 706 inside the flocculation maturation zone. The rotating rod 706 is equipped with an upper limit block 723 and a lower limit block 711. An electromagnet 712 is installed at the bottom of the carbonate softening tank 7 outside the conical sludge sleeve 715. The electromagnet 712 actually adopts a fully sealed, potted design. The shell is made of Hastelloy, and the coil is ceramic insulated and vacuum epoxy encapsulated. The electromagnet 712 does not directly contact the sewage. Its power supply is introduced from the external explosion-proof junction box with low-voltage DC power. A push plate 709 is slidably connected to the rotating rod 706 in the vertical direction. An iron block 710 magnetically connected to an electromagnet 712 is enclosed inside the push plate 709. The push plate 709 is located between the upper limit block 723 and the lower limit block 711. The upper limit block 723 and the lower limit block 711 limit the stroke of the push plate 709. A bracket 714 is provided on the rotating rod 706. A scraper 716 is provided on the bracket 714 to scrape the material on the inner wall of the conical sludge sleeve 715. A third drain pipe 713 is provided at the bottom outlet of the carbonate softening tank 7 and is interconnected with the inside of the conical sludge sleeve 715.

[0047] This embodiment of a softening treatment method for high-temperature oilfield wastewater includes the following steps: S1 is used for pre-treatment of produced water from high-temperature, high-silica oilfields to cool it down.

[0048] S2, high-temperature oilfield wastewater enters the pre-desorption and impurity removal tank 1 through the wastewater inlet pipe 101. High-temperature demulsifier enters the pre-desorption and impurity removal tank 1 through the demulsifier pipe 104. Corrosion inhibitor enters the pre-desorption and impurity removal tank 1 sequentially through the corrosion inhibitor pipe 103 and the demulsifier pipe 104. The high-temperature demulsifier breaks down the emulsified oil interface film of the high-temperature oilfield wastewater, causing oil droplets to coalesce. The corrosion inhibitor forms a protective film on the inner wall of the pre-desorption and impurity removal tank 1 to prevent corrosion. A biological stripping agent enters the pre-desorption and impurity removal tank 1 through the stripping agent pipe 106. The first air inlet pipe 10... 7. The compressed air delivered is introduced into the sewage in the form of microbubbles through multiple aeration holes on the first annular aeration pipe 105 to achieve aeration and stirring, so that the agent and sewage are fully mixed. The biological stripper removes the biofilm in the high-temperature oilfield sewage. The coagulant enters the pre-desorption and impurity removal tank 1 through the first coagulant aid pipe 108. The coagulant causes suspended particles and corrosion products to aggregate into flocs, which settle in the conical sludge hopper 109. The settled sludge is discharged through the first sewage pipe 110. The pretreated high-temperature oilfield sewage enters the barium strontium adsorption tank 3 through the first conveying pipe 2.

[0049] S3, the wastewater inside the barium and strontium adsorption tank 3 passes sequentially through the coarse quartz sand layer 303, the chelating resin layer 302, and the fine quartz sand layer 301. The countercurrent adsorption method can prolong the contact time between the wastewater and the resin and improve the adsorption efficiency. The coarse quartz sand layer 303 achieves uniform water distribution. The chelating resin layer 302 adsorbs barium and strontium in the wastewater and blocks the formation of barium sulfate and strontium sulfate scale in high-temperature oilfield wastewater. The fine quartz sand layer 301 filters resin debris in the wastewater. The wastewater after the removal of barium and strontium enters the silicate pre-removal tank 5 through the second conveying pipe 4.

[0050] S4, the acid-base regulator enters the silicate pre-removal tank 5 through the pH pipe 502, the dispersant enters the silicate pre-removal tank 5 through the first dispersant pipe 503, and the magnesium oxide suspension enters the silicate pre-removal tank 5 through the magnesium oxide suspension pipe 504. The wastewater, acid-base regulator, dispersant and magnesium oxide suspension are thoroughly stirred. The acid-base regulator adjusts the pH value of the wastewater to 8.5-9.0. The magnesium ions in the magnesium oxide suspension cause the silicate ions in the wastewater to form magnesium silicate flocs. The dispersant prevents the magnesium silicate flocs in the wastewater from agglomerating. The settled magnesium silicate flows out through the second drain pipe 507. The desiliconized wastewater enters the carbonate softening tank 7 through the third conveying pipe 6.

[0051] The method for fully mixing wastewater, acid-base regulator, dispersant and magnesium oxide suspension is as follows: the output shaft of the first motor 501 drives the gear 505 to rotate, the gear 505 drives the gear ring 506 to rotate through meshing with the gear ring 506, the gear ring 506 drives the scraper 509 to rotate, the scraper 509 scrapes away impurities from the inner side wall of the silicate pre-removal tank 5, and the multiple stirring rods 508 on the scraper 509 rotate to fully mix the wastewater, acid-base regulator, dispersant and magnesium oxide suspension.

[0052] S5, the dispersant enters the carbonate softening tank 7 through the second dispersant pipe 701, the coagulant aid enters the carbonate softening tank 7 through the second coagulant aid pipe 702, the soda ash solution enters the carbonate softening tank 7 through the soda ash pipe 704, and the chelating agent enters the carbonate softening tank 7 through the chelating agent pipe 703. The carbonate ions in the soda ash solution react with the calcium ions in the wastewater to form calcium carbonate precipitate. The chelating agent guides the ions to form large-particle crystals. The coagulant aid and dispersant are used to enhance the sedimentation effect of calcium carbonate.

[0053] The output shaft of the second motor 705 drives the rotating rod 706 to rotate. Multiple blades 708 on the rotating rod 706 are stirred at high speed inside the central guide tube 707, which fully shears and mixes the sewage with dispersant, coagulant, soda ash solution and chelating agent. Multiple mixing rods 720 on the rotating rod 706 rotate to fully stir the mixed solution. The upper filter screen 719 and the lower filter screen 717 intercept the fine particles that have not settled, and accelerate the settling of the sediment inside the conical sludge sleeve 715. The sludge scraper 716 rotating on the rotating rod 706 scrapes away the impurities on the inner wall of the conical sludge sleeve 715. The sediment is discharged through the third drain pipe 713, and the purified sewage flows into the stabilizing tank 9 through the fourth conveying pipe 8.

[0054] The method to accelerate the settling of sediment inside the conical sludge sleeve 715 is as follows: through the magnetic connection between the electromagnet 712 and the iron block 710 inside the pusher plate 709, the iron block 710 drives the pusher plate 709 to slide vertically on the rotating rod 706. The pusher plate 709 moves between the upper limit block 723 and the lower limit block 711. When the pusher plate 709 moves downward, it squeezes the sewage inside the conical sludge sleeve 715. After being squeezed, the sewage flows upward from the lower filter screen 717. The lower filter screen 717 filters impurities in the water, and the impurities attached to the lower filter screen 717 will settle downward, shortening the time consumed by natural settling. When the pusher plate 709 moves upward, the sewage flows downward on the upper filter screen 719 and the lower filter screen 717, causing the impurities on the surface of the upper filter screen 719 and the lower filter screen 717 to fall off.

[0055] S6, the water inside the stabilizing tank 9 passes sequentially through the modified activated carbon layer 901 and the exchange resin layer 902. The modified activated carbon layer 901 captures residual active silicon, trace organic matter and colloidal particles in the water, and the exchange resin layer 902 removes residual divalent metal ions such as calcium and magnesium, thus completing the softening treatment of the wastewater.

[0056] This embodiment focuses on the treatment of high-temperature oilfield wastewater. Before treatment, the wastewater had the following characteristics: suspended solids 60–80 mg / L, oil content 80–100 mg / L, barium ion content 35–45 mg / L, strontium ion content 25–35 mg / L, calcium ion content 350–450 mg / L, silica content 180–220 mg / L, and pH 7.2–7.8. A fixed process was used: pre-desorption and impurity removal → barium and strontium adsorption → silicate pre-removal → carbonate softening → deep purification in a stabilizing tank. After treatment, the wastewater had the following characteristics: suspended solids ≤10 mg / L, oil content ≤8 mg / L, barium ion content ≤0.5 mg / L, strontium ion content ≤0.3 mg / L, calcium ion content ≤30 mg / L, silica content ≤20 mg / L, and pH 7.5, as shown in Table 1.

[0057] Table 1 Comparison of water quality indicators before and after wastewater treatment As shown in the table above, this embodiment achieves significant removal of key indicators such as suspended solids, oil content, barium ions, strontium ions, calcium ions, and silica in high-temperature oilfield wastewater through synergistic treatment of pre-desorption and impurity removal, barium and strontium adsorption, silica pre-removal, carbonate softening, and deep purification in the stabilizing tank. The water quality after treatment is significantly better than before treatment, achieving the expected softening and purification effect.

[0058] The completion status of this embodiment is shown in Table 2.

[0059] Table 2 Comparison of Project Technical Objectives Achievement As shown in the table above, the technical objectives of this embodiment, including daily processing capacity, suspended solids removal rate, barium, strontium, and calcium ion removal rate, silica removal rate, water recovery rate, and continuous operation cycle, have all been achieved or exceeded, verifying that the process route of this invention is stable and reliable and has engineering application value.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A softening treatment device for high-temperature oilfield wastewater, characterized in that: Oilfield wastewater enters a pre-desorption and impurity removal tank (1) for impurity and pollution removal. High-temperature demulsifier, corrosion inhibitor, and biological stripping agent are added sequentially to the pre-desorption and impurity removal tank (1). The side wall output end of the pre-desorption and impurity removal tank (1) is connected to the bottom inlet end of a barium-strontium adsorption tank (3) via a first conveying pipe (2). The barium-strontium adsorption tank (3) is equipped with a fixed-bed adsorption structure, which consists of a fine quartz sand layer (301), a chelating resin layer (302), and a coarse quartz sand layer (303) arranged sequentially from top to bottom. The top outlet end of the barium-strontium adsorption tank (3) is connected to the top inlet end of a silicate pre-desorption tank (5) via a second conveying pipe (4). The silicate pre-removal tank (5) is connected to the top inlet of the carbonate softening tank (7) via a third conveying pipe (6). The silicate pre-removal tank (5) is connected to the top inlet of the carbonate softening tank (7) via a third conveying pipe (6). The carbonate softening tank (7) is connected to the top inlet of the carbonate softening tank (7) via a fourth conveying pipe (8). The carbonate softening tank (9) is connected to the bottom in a stabilizing tank (9) via a modified activated carbon layer (901) and an exchange resin layer (902) from top to bottom. The stabilizing tank (9) is connected to the bottom in a discharge pipe (903) via a third conveying pipe (6).

2. The softening treatment device for high-temperature oilfield wastewater according to claim 1, characterized in that: The pre-desorption and impurity removal tank (1) is provided with, from top to bottom, an inclined plate oil removal cylinder (102), an aeration and stirring zone (111), and a conical sludge hopper (109) that are interconnected. A wastewater inlet pipe (101) is provided at the top of the pre-desorption and impurity removal tank (1) and is interconnected with the inclined plate oil removal cylinder (102). Oilfield wastewater enters the pre-desorption and impurity removal tank (1) through the wastewater inlet pipe (101). A demulsifier pipe (104) is provided on the side wall of the pre-desorption and impurity removal tank (1) and is interconnected with the inclined plate oil removal cylinder (102). A corrosion inhibitor pipe (103) is provided on the demulsifier pipe (104) and is interconnected with it. High-temperature demulsifier enters the pre-desorption and impurity removal tank (1) through the demulsifier pipe (104), and corrosion inhibitor enters the pre-desorption and impurity removal tank (1) sequentially through the corrosion inhibitor pipe (103) and the demulsifier pipe (104). 1) A stripping agent pipe (106) is provided on the side wall and is connected to the aeration and mixing zone (111). The biological stripping agent enters the interior of the pre-desorption and impurity removal tank (1) through the stripping agent pipe (106). A first annular aeration pipe (105) is provided on the inner side wall of the aeration and mixing zone (111). A first air inlet pipe (107) is provided on the side wall of the pre-desorption and impurity removal tank (1) and is connected to the first annular aeration pipe (105). The first annular aeration pipe (105) is uniformly machined with multiple aeration holes along the circumference. A first coagulant aid pipe (108) is provided on the side wall of the pre-desorption and impurity removal tank (1) and is connected to the conical sludge hopper (109). The coagulant aid enters the interior of the pre-desorption and impurity removal tank (1) through the first coagulant aid pipe (108). A first sewage discharge pipe (110) is provided at the bottom of the pre-desorption and impurity removal tank (1) and is connected to the conical sludge hopper (109).

3. The softening treatment device for high-temperature oilfield wastewater according to claim 1, characterized in that: The silicate pre-removal tank (5) is provided with a pH pipe (502), a first dispersant pipe (503), and a magnesium oxide suspension pipe (504) connected to its interior at the top. The acid-base adjuster enters the silicate pre-removal tank (5) through the pH pipe (502), the dispersant enters the silicate pre-removal tank (5) through the first dispersant pipe (503), and the magnesium oxide suspension enters the silicate pre-removal tank (5) through the magnesium oxide suspension pipe (504). The bottom opening of the silicate pre-removal tank (5) is provided with a second drain pipe (507) connected to its interior.

4. The softening treatment device for high-temperature oilfield wastewater according to claim 3, characterized in that: The silicate pre-removal tank (5) is equipped with a first motor (501) at the top. The output shaft of the first motor (501) is fixedly connected to a gear (505). A scraper (509) for scraping sludge from the inner wall of the silicate pre-removal tank (5) is rotatably installed inside the silicate pre-removal tank (5). Multiple stirring rods (508) are provided on the scraper (509). A gear ring (506) that meshes with the gear (505) is provided on the top of the scraper (509).

5. The softening treatment device for high-temperature oilfield wastewater according to claim 1, characterized in that: The top of the carbonate softening tank (7) is provided with a second dispersant pipe (701), a second coagulant aid pipe (702), a chelating agent pipe (703), and a soda ash pipe (704) that are interconnected with the interior. The dispersant enters the interior of the carbonate softening tank (7) through the second dispersant pipe (701), the coagulant aid enters the interior of the carbonate softening tank (7) through the second coagulant aid pipe (702), the soda ash solution enters the interior of the carbonate softening tank (7) through the soda ash pipe (704), and the chelating agent enters the interior of the carbonate softening tank (7) through the chelating agent pipe (703).

6. The softening treatment device for high-temperature oilfield wastewater according to claim 5, characterized in that, The carbonate softening tank (7) is provided with interconnected mixing reaction zone, flocculation maturation zone and high-efficiency sedimentation zone from top to bottom. The mixing reaction zone is: the carbonate softening tank (7) is provided with a central guide tube (707). The flocculation maturation zone is: the carbonate softening tank (7) is provided with a sleeve (718), and the top of the sleeve (718) is provided with an upper filter screen (719). The high-efficiency sedimentation zone is: the bottom of the sleeve (718) is provided with a conical sludge sleeve (715) that is interconnected with it, and the top of the conical sludge sleeve (715) is provided with a lower filter screen (717) that is connected to the bottom of the sleeve (718). The lower filter screen (717) is located below the upper filter screen (719).

7. The softening treatment device for high-temperature oilfield wastewater according to claim 5, characterized in that: The carbonate softening tank (7) is equipped with a second motor (705) at the top. The output shaft of the second motor (705) is fixedly connected to a rotating rod (706). The rotating rod (706) is equipped with multiple blades (708) located inside a central guide tube (707). The inner wall of the central guide tube (707) is equipped with a second annular aeration pipe (722). The second annular aeration pipe (722) is equipped with multiple aeration holes along the circumferential direction. The carbonate softening tank (7) is equipped with a second air inlet pipe (721) that is interconnected with the second annular aeration pipe (722). The rotating rod (706) is equipped with multiple mixing rods (720) located inside the flocculation maturation zone. The rotating rod (706) is equipped with an upper limit block (723) and a lower limit block. (711) An electromagnet (712) is provided at the bottom of the carbonate softening tank (7) outside the conical sludge sleeve (715). A push plate (709) is slidably connected to the rotating rod (706) in the vertical direction. An iron block (710) magnetically connected to the electromagnet (712) is enclosed inside the push plate (709). The push plate (709) is located between the upper limit block (723) and the lower limit block (711). A bracket (714) is provided on the rotating rod (706). A scraper (716) is provided on the bracket (714) to scrape the material on the inner wall of the conical sludge sleeve (715). A third drain pipe (713) is provided at the bottom outlet end of the carbonate softening tank (7) and is interconnected with the inside of the conical sludge sleeve (715).

8. A method for softening wastewater from high-temperature oilfields, using the softening device for high-temperature oilfield wastewater as described in claim 1, characterized in that, Includes the following steps: S1 is used for cooling pretreatment of produced water from high-temperature, high-silicon oilfields. S2, high-temperature oilfield wastewater enters the pre-desorption and impurity removal tank (1) through the wastewater inlet pipe (101). High-temperature demulsifier enters the pre-desorption and impurity removal tank (1) through the demulsifier pipe (104). Corrosion inhibitor enters the pre-desorption and impurity removal tank (1) sequentially through the corrosion inhibitor pipe (103) and the demulsifier pipe (104). The high-temperature demulsifier breaks down the emulsified oil interface film of the high-temperature oilfield wastewater, causing oil droplets to coalesce. The corrosion inhibitor forms a protective film on the inner wall of the pre-desorption and impurity removal tank (1) to prevent corrosion of the pre-desorption and impurity removal tank (1). The biological stripper enters the pre-desorption and impurity removal tank (1) through the stripper pipe (106). The biological stripper strips the biofilm in the high-temperature oilfield wastewater. The coagulant enters the pre-desorption and impurity removal tank (1) through the first coagulant pipe (108). The coagulant causes suspended particles and corrosion products to aggregate into flocs, which settle in the conical sludge hopper (109). The settled sludge is discharged through the first sewage pipe (110). The pretreated high-temperature oilfield wastewater enters the barium strontium adsorption tank (3) through the first conveying pipe (2). S3, the wastewater inside the barium and strontium adsorption tank (3) passes through the coarse quartz sand layer (303), the chelating resin layer (302), and the fine quartz sand layer (301) in sequence. The coarse quartz sand layer (303) achieves uniform water distribution, the chelating resin layer (302) adsorbs barium and strontium in the wastewater, and blocks the formation of barium sulfate and strontium sulfate scale in the high-temperature oilfield wastewater. The fine quartz sand layer (301) filters resin debris in the wastewater. The wastewater after removing barium and strontium enters the silicate pre-removal tank (5) through the second conveying pipe (4). S4, the acid-base regulator enters the silicate pre-removal tank (5) through the pH pipe (502), the dispersant enters the silicate pre-removal tank (5) through the first dispersant pipe (503), and the magnesium oxide suspension enters the silicate pre-removal tank (5) through the magnesium oxide suspension pipe (504). The wastewater, acid-base regulator, dispersant and magnesium oxide suspension are thoroughly stirred. The acid-base regulator adjusts the pH value of the wastewater to 8.5-9.

0. The magnesium ions in the magnesium oxide suspension cause the silicate ions in the wastewater to form magnesium silicate flocs. The dispersant prevents the magnesium silicate flocs in the wastewater from agglomerating. The settled magnesium silicate flows out through the second drain pipe (507). The desiliconized wastewater enters the carbonate softening tank (7) through the third conveying pipe (6). S5, the dispersant enters the carbonate softening tank (7) through the second dispersant pipe (701), the coagulant aid enters the carbonate softening tank (7) through the second coagulant aid pipe (702), the soda ash solution enters the carbonate softening tank (7) through the soda ash pipe (704), and the chelating agent enters the carbonate softening tank (7) through the chelating agent pipe (703). The carbonate ions in the soda ash solution react with the calcium ions in the wastewater to form calcium carbonate precipitate. The chelating agent guides the ions to form large-particle crystals. The coagulant aid and dispersant are used to enhance the sedimentation effect of calcium carbonate. The output shaft of the second motor (705) drives the rotating rod (706) to rotate. Multiple blades (708) on the rotating rod (706) are stirred at high speed inside the central guide tube (707) to fully shear and mix the sewage with dispersant, coagulant, soda ash solution and chelating agent. Multiple mixing rods (720) on the rotating rod (706) rotate to fully stir the mixed solution. The upper filter screen (719) and the lower filter screen (717) intercept the fine particles that have not settled, and accelerate the settling of the sediment inside the conical sludge sleeve (715). The scraper (716) rotating on the rotating rod (706) scrapes off the impurities on the inner wall of the conical sludge sleeve (715). The sediment is discharged through the third drain pipe (713). The purified sewage flows into the stabilizer (9) through the fourth conveying pipe (8). S6, the water inside the stabilizing tank (9) passes through the modified activated carbon layer (901) and the exchange resin layer (902) in sequence. The modified activated carbon layer (901) captures the residual active silicon, trace organic matter and colloidal particles in the water, and the exchange resin layer (902) removes the residual calcium, magnesium and other divalent metal ions, thus completing the softening treatment of the sewage.

9. The softening treatment method for high-temperature oilfield wastewater according to claim 8, characterized in that: The method for fully stirring the wastewater, acid-base regulator, dispersant and magnesium oxide suspension in S4 is as follows: the output shaft of the first motor (501) drives the gear (505) to rotate, the gear (505) drives the gear ring (506) to rotate through meshing transmission, the gear ring (506) drives the scraper (509) to rotate, the scraper (509) scrapes off the impurities on the inner side wall of the silicate pre-removal tank (5), and the multiple stirring rods (508) on the scraper (509) rotate to fully stir the wastewater, acid-base regulator, dispersant and magnesium oxide suspension.

10. The softening treatment method for high-temperature oilfield wastewater according to claim 8, characterized in that: The method for accelerating the settling of sediment inside the conical sludge sleeve (715) in S5 is as follows: through the magnetic connection between the electromagnet (712) and the iron block (710) inside the push plate (709), the iron block (710) drives the push plate (709) to slide vertically on the rotating rod (706), and the push plate (709) moves between the upper limit block (723) and the lower limit block (711). When the push plate (709) moves downward, it squeezes the conical sludge sleeve (715). The sewage inside the sludge sleeve (715) is squeezed and flows back upward from the lower filter screen (717). The lower filter screen (717) filters impurities in the water. The impurities attached to the lower filter screen (717) will settle downward, shortening the time consumed by natural settling. When the push plate (709) moves upward, the sewage flows downward in the upper filter screen (719) and the lower filter screen (717), causing the impurities on the surface of the upper filter screen (719) and the lower filter screen (717) to fall off.

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