Iron-containing produced water flocculant and method of making same

Abstract

This invention belongs to the field of wastewater treatment technology, specifically relating to a flocculant for iron-containing produced water and its preparation method. The preparation method is as follows: Under a nitrogen atmosphere, dodecylamine and allyl chloride undergo a substitution reaction in an ethanol solution with copper chloride as a catalyst to obtain a first functional monomer; under a nitrogen atmosphere, 12-aminododecanoic acid and allyl chloride undergo a substitution reaction in an ethanol solution with copper chloride as a catalyst to obtain a second functional monomer; the first and second functional monomers undergo a polymerization reaction through an initiator to obtain the flocculant. This invention features a simple synthesis process, low dosage, and good flocculation effect.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to an iron-containing produced water flocculant and its preparation method. Background Technology

[0002] Polymer flooding is a crucial technology for enhancing oil recovery in oilfields. It involves adding polymer flooding agents to aqueous solutions to increase the viscosity, thereby controlling mobility and improving oil recovery. In chemical flooding, increasing the viscosity of the polymer solution is key to expanding injection reach, improving the oil-water mobility ratio, and significantly enhancing oil recovery.

[0003] Sulfide and ferrous ions in the water used for polymer synthesis are the main water quality factors that cause a significant decrease in the viscosity of the polymer solution.

[0004] High iron ion content in produced water from some blocks such as Binnan, Dongxin, and Shengcai will significantly impact subsequent chemical flooding operations, necessitating effective removal or control of iron ions. Chemical flooding is about to commence in the Ying 8 Sha 2 8485 unit and Yong 8 block of Dongxin, where the iron ion content in the polymer preparation water exceeds 10 mg / L, affecting polymer viscosity and urgently requiring effective treatment. Iron-containing produced water from Binwulian, Yongyi, and 102 stations showed a more than 35% increase in polymer viscosity after iron removal treatment. Conducting research on iron-containing produced water treatment is of great significance for improving polymer viscosity and promoting the implementation of chemical flooding.

[0005] Adding flocculants to produced water is a relatively simple and effective method for iron removal.

[0006] CN114656064A discloses a method for removing ferric and ferrous ions from an ammonium sulfate solution, comprising the following steps: mixing the ammonium sulfate solution to be treated with an oxidant to carry out an oxidation reaction, obtaining a pretreated solution; mixing the pretreated solution with ammonia water to carry out a precipitation reaction, obtaining a suspension; and using diatomaceous earth to adsorb the precipitate in the suspension. This invention first mixes the ammonium sulfate solution with an oxidant to remove ferric and ferrous ions from the ammonium sulfate solution. 2+ Oxidized to Fe 3+ Then, ammonia water was used to remove Fe. 3+ The iron and ferrous ions in the ammonium sulfate solution are converted into Fe(OH)3 precipitate and then adsorbed by diatomaceous earth, thereby improving the removal efficiency. However, this invention requires the combined use of multiple processes such as oxidation, sedimentation, and adsorption, resulting in a lengthy and cumbersome process.

[0007] CN117205611A discloses a method for removing iron ions from electrolyte using resin, relating to the field of electrolytic hydrogen production technology, with the main objective of improving the efficiency of iron ion removal from electrolyte. The main technical solution of this invention is a method for removing iron ions from electrolyte using resin, comprising the following steps: Step 1, pretreating resin particles; Step 2, packing the resin particles into a chromatography column; Step 3, adding the electrolyte dropwise into the chromatography column using a burette, controlling the average flow rate of the electrolyte through the chromatography column to 22-25 m / h by controlling the dropping speed of the burette. However, the iron removal rate of this invention is only about 75.8-91.6%, and the iron content is still 0.44-1.28 mg / L, which cannot meet the needs of on-site applications. Furthermore, the resin requires regeneration after long-term use, increasing costs. Summary of the Invention

[0008] This invention addresses the shortcomings of existing technologies by providing a flocculant for iron-containing produced water and its preparation method. This invention features a simple synthesis process, low dosage, and excellent flocculation effect.

[0009] Therefore, in order to achieve the above objectives, on the one hand, the present invention provides a method for preparing an iron-containing produced water flocculant, the method comprising: (1) under a nitrogen atmosphere, in an ethanol solution, dodecylamine and allyl chloride undergo a substitution reaction under the condition of copper chloride as a catalyst to obtain a first functional monomer; (2) under a nitrogen atmosphere, in an ethanol solution, 12-aminododecanoic acid and allyl chloride undergo a substitution reaction under the condition of copper chloride as a catalyst to obtain a second functional monomer; (3) the first functional monomer and the second functional monomer undergo a polymerization reaction through an initiator to obtain a flocculant.

[0010] In another aspect, the present invention provides a flocculant for iron-containing produced water, the molecular structural formula of which is as follows:

[0011]

[0012] Where m = 5000 - 50000;

[0013] n = 5000 - 50000.

[0014] The flocculant for iron-containing produced water of this invention has a linear molecular structure with relatively long and flexible functional groups on its branches, forming a network structure that can sweep up iron ions and other particles in the solution, thus achieving an overall sedimentation effect. The carboxyl groups in the molecule can capture iron ions through chelation, while the amino groups (including primary and secondary amines) can adsorb iron ions through lone pair electrons, achieving a flocculation effect. This invention not only flocculates iron ions but also causes solid particles and colloids in the solution to settle out together.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0016] (1) The iron-containing produced water flocculant of the present invention has a wide range of raw material sources, simple synthesis process, strong adaptability, low dosage, and can meet the needs of environmental protection and oilfield development.

[0017] (2) The iron-containing produced water flocculant of the present invention has the characteristics of low concentration and high efficiency. When the concentration is 1 mg / L, it can completely flocculate simulated water containing 20 mg / L iron ions or produced water containing 15 mg / L iron ions. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] According to a first aspect of the present invention, a method for preparing an iron-containing produced water flocculant is disclosed, the method comprising:

[0020] (1) Under a nitrogen atmosphere, in an ethanol solution, dodecylamine and allyl chloride undergo a substitution reaction with copper chloride as a catalyst to obtain the first functional monomer.

[0021] (2) Under a nitrogen atmosphere, in an ethanol solution, 12-aminododecanoic acid and allyl chloride undergo a substitution reaction with copper chloride as a catalyst to obtain a second functional monomer.

[0022] (3) The first functional monomer and the second functional monomer undergo a polymerization reaction through an initiator to obtain a flocculant.

[0023] In this invention, preferably, the mass ratio of allyl chloride, ethanol, copper chloride and dodecylamine in step (1) is 0.3-0.45:10-20:0.02-0.04:1.

[0024] More preferably, the mass ratio of allyl chloride, ethanol, copper chloride and dodecylamine is 0.36-0.45:15-20:0.025-0.035:1.

[0025] In this invention, preferably, the substitution reaction temperature in step (1) is 50-60°C and the time is 30-60 min.

[0026] More preferably, the substitution reaction in step (1) is carried out at a temperature of 55-60°C for a time of 40-60 min.

[0027] In this invention, preferably, the mass ratio of allyl chloride, ethanol, copper chloride and 12-aminododecanoic acid in step (2) is 0.3-0.4:10-20:0.02-0.04:1.

[0028] More preferably, the mass ratio of allyl chloride, ethanol, copper chloride and 12-aminododecanoic acid is 0.32-0.4:10-15:0.03-0.04:1.

[0029] In this invention, preferably, the substitution reaction temperature in step (2) is 60-70°C and the time is 60-120 min.

[0030] More preferably, the substitution reaction in step (2) is carried out at a temperature of 65-70°C for a time of 80-120 min.

[0031] In this invention, preferably, the mass ratio of the first functional monomer, the second functional monomer, and the initiator in step (3) is 1-10:1-10:0.5-1.

[0032] More preferably, in step (3), the mass ratio of the first functional monomer, the second functional monomer, and the initiator is 3-9:8-10:0.6-0.9.

[0033] In this invention, preferably, the initiator in step (3) is a mixed solution of persulfate and sodium bisulfite, with concentrations of 8-12 wt% and 3-5 wt%, respectively.

[0034] More preferably, the persulfate is one of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0035] In this invention, preferably, the polymerization reaction temperature in step (3) is 50-60°C and the heat preservation reaction time is 30-60 min.

[0036] More preferably, the polymerization reaction temperature in step (3) is 55-60°C and the heat preservation reaction time is 40-60 min.

[0037] According to a more specific preferred embodiment, the preparation method of the iron-containing produced water flocculant specifically includes the following steps:

[0038] (1) Preparation of the first functional monomer

[0039] Dodecylamine, allyl chloride, ethanol, and copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid, and the pH was adjusted to 8-9. The reaction was carried out under heat and distilled under reduced pressure to obtain a viscous solid. The solid was then recrystallized with ethyl acetate to obtain the first functional monomer.

[0040] The heating and heat preservation reaction is carried out at a temperature of 50-60℃ for 30-60 minutes.

[0041] (2) Preparation of the second functional monomer

[0042] 12-Aminododecanoic acid, allyl chloride, ethanol, and copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid, and the pH was adjusted to 8-9. The reaction was carried out under heat and distilled under reduced pressure to obtain a viscous solid. The solid was then recrystallized with ethyl acetate to obtain the second functional monomer.

[0043] The heating and heat preservation reaction temperature is 60-70℃, and the time is 60-120min.

[0044] (3) Preparation of flocculants

[0045] Add the first functional monomer, the second functional monomer, water, and potassium dihydrogen phosphate to the reactor, purge with nitrogen to replace the air in the reactor, stir to dissolve, adjust the pH to 7-8, slowly add the initiator, the solution gradually becomes viscous, raise the temperature and keep it at the temperature to carry out the polymerization reaction, adjust the pH to 7-8, cool down to below 30°C, precipitate the product with ethanol, dry and granulate to obtain the flocculant.

[0046] The polymerization reaction temperature is 50-60℃, and the reaction time is 30-60 min.

[0047] The reaction equation for the synthesis of the iron-containing produced water flocculant of the present invention is as follows:

[0048]

[0049] Secondly, this invention discloses a flocculant for iron-containing produced water, the molecular structural formula of which is as follows:

[0050]

[0051] Where m = 5000 - 50000;

[0052] n = 5000 - 50000.

[0053] Preferably, the viscosity-average molecular weight of the flocculant is 2,000,000-1,000,000.

[0054] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0055] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

[0056] The present invention will be further described below with reference to specific embodiments.

[0057] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0058] Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available chemically pure reagents.

[0059] The present invention will be further described below with reference to specific embodiments:

[0060] Example 1

[0061] (1) Preparation of the first functional monomer

[0062] 10g dodecylamine, 3g allyl chloride, 100g ethanol, and 0.2g copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. The pH was adjusted to 8-9 with sodium hydroxide. The mixture was heated to 50°C and kept at that temperature for 60 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the first functional monomer.

[0063] (2) Preparation of the second functional monomer

[0064] 10g of 12-aminododecanoic acid, 3g of allyl chloride, 100g of ethanol, and 0.2g of copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. The pH was adjusted to 8-9 with sodium hydroxide. The mixture was heated to 70°C and kept at that temperature for 60 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the second functional monomer.

[0065] (3) Preparation of flocculants

[0066] Add 1g of the first functional monomer, 10g of the second functional monomer, 80g of water, and 0.1g of potassium dihydrogen phosphate to the reactor. Purge with nitrogen to replace the air in the reactor, stir to dissolve, adjust the pH to 7-8 with sodium hydroxide solution, and slowly add 0.5g of initiator containing 12wt% sodium persulfate and 5wt% sodium bisulfite. The solution gradually becomes viscous. Raise the temperature to 50℃ and keep the reaction at that temperature for 30 minutes to induce polymerization. Adjust the pH to 7-8 with sodium hydroxide solution, cool the temperature to below 30℃, precipitate the product with ethanol, dry and granulate to obtain the flocculant.

[0067] Example 2

[0068] (1) Preparation of the first functional monomer

[0069] 10g dodecylamine, 4.5g allyl chloride, 200g ethanol, and 0.25g copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. Sodium hydroxide was used to adjust the pH to 8-9. The mixture was heated to 60°C and kept at that temperature for 30 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the first functional monomer.

[0070] (2) Preparation of the second functional monomer

[0071] 10g of 12-aminododecanoic acid, 4g of allyl chloride, 200g of ethanol, and 0.25g of copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. The pH was adjusted to 8-9 with sodium hydroxide. The mixture was heated to 60℃ and kept at that temperature for 120 min. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the second functional monomer.

[0072] (3) Preparation of flocculants

[0073] Add 3g of the first functional monomer, 8g of the second functional monomer, 85g of water, and 0.12g of potassium dihydrogen phosphate to the reactor. Purge with nitrogen to replace the air in the reactor, stir to dissolve, adjust the pH to 7-8 with sodium hydroxide solution, and slowly add 0.6g of initiator containing 12wt% sodium persulfate and 5wt% sodium bisulfite. The solution gradually becomes viscous. Raise the temperature to 53℃ and maintain the reaction for 40min to induce polymerization. Adjust the pH to 7-8 with sodium hydroxide solution, cool to below 30℃, precipitate the product with ethanol, dry and granulate to obtain the flocculant.

[0074] Example 3

[0075] (1) Preparation of the first functional monomer

[0076] 10g dodecylamine, 3.3g allyl chloride, 150g ethanol, and 0.3g copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. Sodium hydroxide was used to adjust the pH to 8-9. The mixture was heated to 52°C and kept at that temperature for 50 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the first functional monomer.

[0077] (2) Preparation of the second functional monomer

[0078] 10g of 12-aminododecanoic acid, 3.2g of allyl chloride, 120g of ethanol, and 0.25g of copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. The pH was adjusted to 8-9 with sodium hydroxide. The mixture was heated to 65°C and kept at that temperature for 80 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the second functional monomer.

[0079] (3) Preparation of flocculants

[0080] Add 5g of the first functional monomer, 6g of the second functional monomer, 90g of water, and 0.14g of potassium dihydrogen phosphate to the reactor. Purge with nitrogen to replace the air in the reactor, stir to dissolve, adjust the pH to 7-8 with sodium hydroxide solution, and slowly add 0.7g of initiator containing 10wt% potassium persulfate and 4wt% sodium bisulfite. The solution gradually becomes viscous. Raise the temperature to 55℃ and maintain the reaction for 45min to induce polymerization. Adjust the pH to 7-8 with sodium hydroxide solution, cool to below 30℃, precipitate the product with ethanol, dry and granulate to obtain the flocculant.

[0081] Example 4

[0082] (1) Preparation of the first functional monomer

[0083] 10g dodecylamine, 4g allyl chloride, 180g ethanol, and 0.35g copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. Sodium hydroxide was used to adjust the pH to 8-9. The mixture was heated to 55°C and kept at that temperature for 45 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the first functional monomer.

[0084] (2) Preparation of the second functional monomer

[0085] 10g of 12-aminododecanoic acid, 3.8g of allyl chloride, 170g of ethanol, and 0.3g of copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. The pH was adjusted to 8-9 with sodium hydroxide. The mixture was heated to 68℃ and kept at that temperature for 90 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the second functional monomer.

[0086] (3) Preparation of flocculants

[0087] Add 7g of the first functional monomer, 4g of the second functional monomer, 95g of water, and 0.16g of potassium dihydrogen phosphate to the reactor. Purge with nitrogen to replace the air in the reactor, stir to dissolve, adjust the pH to 7-8 with sodium hydroxide solution, and slowly add 0.8g of initiator containing 10wt% potassium persulfate and 4wt% sodium bisulfite. The solution gradually becomes viscous. Raise the temperature to 55℃ and keep the reaction at that temperature for 60min to induce polymerization. Adjust the pH to 7-8 with sodium hydroxide solution, cool the temperature to below 30℃, precipitate the product with ethanol, dry and granulate to obtain the flocculant.

[0088] Example 5

[0089] (1) Preparation of the first functional monomer

[0090] 10g dodecylamine, 3.6g allyl chloride, 150g ethanol, and 0.4g copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. Sodium hydroxide was used to adjust the pH to 8-9. The mixture was heated to 60°C and kept at that temperature for 35 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the first functional monomer.

[0091] (2) Preparation of the second functional monomer

[0092] 10g of 12-aminododecanoic acid, 3.4g of allyl chloride, 150g of ethanol, and 0.35g of copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. The pH was adjusted to 8-9 with sodium hydroxide. The mixture was heated to 70°C and kept at that temperature for 70 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the second functional monomer.

[0093] (3) Preparation of flocculants

[0094] Add 9g of the first functional monomer, 2g of the second functional monomer, 100g of water, and 0.18g of potassium dihydrogen phosphate to the reactor. Purge with nitrogen to replace the air in the reactor, stir to dissolve, adjust the pH to 7-8 with sodium hydroxide solution, and slowly add 0.9g of initiator containing 8wt% ammonium persulfate and 3wt% sodium bisulfite. The solution gradually becomes viscous. Raise the temperature to 60℃ and keep the reaction at that temperature for 50min to induce polymerization. Adjust the pH to 7-8 with sodium hydroxide solution, cool the temperature to below 30℃, precipitate the product with ethanol, dry and granulate to obtain the flocculant.

[0095] Example 6

[0096] (1) Preparation of the first functional monomer

[0097] 10g dodecylamine, 3.8g allyl chloride, 156g ethanol, and 0.4g copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. Sodium hydroxide was used to adjust the pH to 8-9. The mixture was heated to 60°C and kept at that temperature for 40 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the first functional monomer.

[0098] (2) Preparation of the second functional monomer

[0099] 10g of 12-aminododecanoic acid, 3.6g of allyl chloride, 160g of ethanol, and 0.4g of copper chloride were added to a reactor. Nitrogen gas was introduced to replace the air in the reactor. The mixture was stirred to dissolve the solid. The pH was adjusted to 8-9 with sodium hydroxide. The mixture was heated to 70°C and kept at that temperature for 90 minutes. The solid was obtained by vacuum distillation and recrystallized with ethyl acetate to obtain the second functional monomer.

[0100] (3) Preparation of flocculants

[0101] Add 10g of the first functional monomer, 1g of the second functional monomer, 100g of water, and 0.2g of potassium dihydrogen phosphate to the reactor. Purge with nitrogen to replace the air in the reactor, stir to dissolve, adjust the pH to 7-8 with sodium hydroxide solution, and slowly add 1g of initiator containing 8wt% ammonium persulfate and 3wt% sodium bisulfite. The solution gradually becomes viscous. Raise the temperature to 58℃ and keep the reaction at this temperature for 30 minutes to induce polymerization. Adjust the pH to 7-8 with sodium hydroxide solution, cool the temperature to below 30℃, precipitate the product with ethanol, dry and granulate to obtain the flocculant.

[0102] Example 7: Evaluation of the effect of simulated water iron ion removal

[0103] Simulated water configuration:

[0104] Dissolve 3.55g of FeCl₂·4H₂O in distilled water and dilute to a volumetric flask (1000ml) to obtain a solution with a ferrous ion concentration of 1000mg / L. Dissolve 4.82g of FeCl₃·6H₂O in distilled water and dilute to a volumetric flask (1000ml) to obtain a solution with a ferric ion concentration of 1000mg / L. Add 10ml of each of the above two solutions to a volumetric flask and dilute to a volumetric flask (1000ml) to obtain a solution with a total ferric ion concentration of 20mg / L, of which the concentrations of ferrous and ferric ions are each 10mg / L.

[0105] The flocculant of the present invention (Examples 1-6) at concentrations of 0.2, 0.5, and 1 mg / L was added to the simulated water, respectively. After flocculation, the total iron ion content was tested, and the flocculation rate was calculated. The test results are shown in Table 1.

[0106] A comparative experiment was conducted using PAM.

[0107] As can be seen from Table 1:

[0108] (1) When the flocculant of the present invention (Examples 1-6) is used at a concentration of 0.2 mg / L, it can make the flocculation rate of simulated water containing 20 mg / L iron ions reach 90% or more, with a maximum of 94%, while the comparative example is 60%, which is significantly lower than that of the present invention.

[0109] (2) When the flocculant of the present invention (Examples 1-6) is used at a concentration of 0.5 mg / L, it can make the flocculation rate of simulated water containing 20 mg / L iron ions reach 95% or more, with a maximum of 98%, compared to 90% in the comparative example, which is significantly lower than that of the present invention.

[0110] (3) When the flocculant of the present invention (Examples 1-6) is used at a concentration of 1 mg / L, it can make the flocculation rate of simulated water containing 20 mg / L iron ions reach 99% or more, and up to 100%, compared to 95% in the comparative example, which is significantly lower than that of the present invention.

[0111] Example 8: Evaluation of Iron Ion Removal Effect in Field-Collected Water

[0112] The total iron ion content in the produced water of a certain block of Shengli Oilfield Dongxin Oil Production Plant was 15 mg / L. 1000 ml of the flocculant of the present invention with concentrations of 0.2, 0.5 and 1 mg / L were added respectively (Examples 1-6). After flocculation, the total iron ion content was tested and the flocculation rate was calculated. The test results are shown in Table 1.

[0113] A comparative experiment was conducted using PAM.

[0114] Table 1. Ferrous ion flocculation results (flocculation rate)

[0115]

[0116] As can be seen from Table 1:

[0117] (1) When the flocculant of the present invention (Examples 1-6) is used at a concentration of 0.2 mg / L, it can make the flocculation rate of the produced water containing 15 mg / L of iron ions reach 97% or more, and up to 99%, while the comparative example is 80%, which is significantly lower than that of the present invention.

[0118] (2) When the flocculant of the present invention (Examples 1-6) is used at a concentration of 0.5 mg / L, it can make the flocculation rate of produced water containing 15 mg / L of iron ions reach 99% or more, and up to 100%, compared with 93% in the comparative example, which is significantly lower than that of the present invention.

[0119] (3) When the flocculant of the present invention (Examples 1-6) is used at a concentration of 1 mg / L, it can achieve a flocculation rate of 100% for produced water containing 15 mg / L of iron ions, and the comparative example is 97%.

[0120] The flocculation effect of this invention is significantly better than that of PAM; at the same time, the flocculation effect of this invention on iron ions in field-extracted water is better than that in simulated water, because field-extracted water has more suspended solids and various impurities and a more complex composition, which plays an auxiliary sweeping role in the flocculation of iron ions.

[0121] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing an iron-containing produced water flocculant, characterized in that, The preparation method includes: (1) Under a nitrogen atmosphere, in an ethanol solution, dodecylamine and allyl chloride undergo a substitution reaction with copper chloride as a catalyst to obtain the first functional monomer. (2) Under a nitrogen atmosphere, in an ethanol solution, 12-aminododecanoic acid and allyl chloride undergo a substitution reaction with copper chloride as a catalyst to obtain a second functional monomer. (3) The first functional monomer and the second functional monomer undergo a polymerization reaction through an initiator to obtain a flocculant.

2. The method for preparing an iron-containing produced water flocculant as described in claim 1, characterized in that, The mass ratio of allyl chloride, ethanol, copper chloride and dodecylamine in step (1) is 0.3-0.45:10-20:0.02-0.04:

1.

3. The method for preparing an iron-containing produced water flocculant as described in claim 2, characterized in that, The mass ratio of allyl chloride, ethanol, copper chloride and dodecylamine is 0.36-0.45:15-20:0.025-0.035:

1.

4. The method for preparing an iron-containing produced water flocculant as described in claim 1, characterized in that, The heating and heat preservation reaction in step (1) is carried out at a temperature of 50-60℃ for 30-60 minutes.

5. The method for preparing an iron-containing produced water flocculant as described in claim 4, characterized in that, The heating and heat preservation reaction in step (1) is carried out at a temperature of 55-60℃ for 40-60 minutes.

6. The method for preparing an iron-containing produced water flocculant as described in claim 1, characterized in that, The mass ratio of allyl chloride, ethanol, copper chloride and 12-aminododecanoic acid in step (2) is 0.3-0.4:10-20:0.02-0.04:

1.

7. The method for preparing an iron-containing produced water flocculant as described in claim 6, characterized in that, The mass ratio of allyl chloride, ethanol, copper chloride and 12-aminododecanoic acid is 0.32-0.4:10-15:0.03-0.04:

1.

8. The method for preparing an iron-containing produced water flocculant as described in claim 1, characterized in that, The heating and heat preservation reaction temperature in step (2) is 60-70℃, and the time is 60-120min.

9. The method for preparing an iron-containing produced water flocculant as described in claim 8, characterized in that, The heating and heat preservation reaction temperature is 65-70℃, and the time is 80-120min.

10. The method for preparing an iron-containing produced water flocculant as described in claim 1, characterized in that, In step (3), the mass ratio of the first functional monomer, the second functional monomer, water, potassium dihydrogen phosphate, and the initiator is 1-10:1-10:80-100:0.1-0.2:0.5-1.

11. The method for preparing an iron-containing produced water flocculant as described in claim 10, characterized in that, The mass ratio of the first functional monomer, the second functional monomer, water, potassium dihydrogen phosphate, and the initiator is 3-9:8-10:90-100:0.15-0.2:0.6-0.

9.

12. The method for preparing an iron-containing produced water flocculant as described in claim 1, characterized in that, The initiator mentioned in step (3) is a mixed solution of persulfate and sodium bisulfite, with concentrations of 8-12 wt% and 3-5 wt%, respectively.

13. The method for preparing an iron-containing produced water flocculant as described in claim 12, characterized in that, The persulfate is one of sodium persulfate, potassium persulfate, or ammonium persulfate.

14. The method for preparing an iron-containing produced water flocculant as described in claim 1, characterized in that, The polymerization reaction temperature in step (3) is 50-60℃, and the reaction time is 30-60min.

15. The method for preparing an iron-containing produced water flocculant as described in claim 14, characterized in that, The polymerization reaction temperature in step (3) is 55-60℃, and the reaction time is 40-60min.

16. A flocculant for iron-containing produced water, characterized in that, The molecular structural formula of the flocculant is as follows: Where m = 5000 - 50000; n＝5000-50000。 17. The iron-containing produced water flocculant as described in claim 16, characterized in that, The viscosity-average molecular weight of the flocculant is 2,000,000-1,000,000.

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