A demulsifier for eliminating the emulsified layer at the oil-water interface in the treatment of oilfield produced fluid and its preparation method

Abstract

The present invention belongs to the technical field of sewage treatment, and particularly relates to a demulsifier for eliminating the emulsified layer at the oil-water interface in the treatment of oilfield produced fluid and a preparation method thereof. The preparation method is as follows: acrylamide, 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, allyl tributyl phosphonium chloride and deionized water are added into a first reactor and heated to dissolve; allyl(diisopropylamino)dimethylsilane, butyl acrylate, deionized water, octylphenol polyoxyethylene ether-10, sodium dodecyl sulfate and potassium dihydrogen phosphate are added into a second reactor and stirred to form an emulsion; an initiator and sodium bisulfite are added into the second reactor, the temperature is raised, and the reaction is carried out under insulation. The mixed solution in the first reactor is poured in, the reaction is continued, the temperature is raised, and the insulation is continued to obtain a viscous liquid; the viscous liquid is dried and granulated to obtain the demulsifier. The demulsifier of the present invention has the characteristics of simple synthesis process and high demulsification rate.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a demulsifier for eliminating an emulsified layer at an oil-water interface for treating oilfield produced fluid and a preparation method thereof. Background Art

[0002] With the continuous advancement of oilfield mining technology and the extension of oilfield mining life, more and more oil wells have entered a high water content period, and the water content in oilfield produced fluid has increased significantly. The water content of some oilfield produced fluids even exceeds 90%. Oilfield produced fluids contain a large amount of suspended impurities, dissolved impurities (such as various gases and salts) and emulsified oil, which makes the treatment of oilfield produced fluids particularly complicated and difficult. In the treatment process, oil-water emulsification is a common problem. Because the produced fluid contains various surfactants, colloids, asphaltene and other components, these components will form a stable oil-water emulsion layer under certain conditions, making it difficult to effectively separate oil and water.

[0003] If emulsions are not properly handled, they can cause many serious problems. In crude oil processing, water and impurities can affect refining efficiency and product quality, leading to equipment corrosion, catalyst poisoning, etc.; in transportation, they can increase pipeline loads, increase transportation costs, and may cause pipeline blockages; in storage, they can reduce crude oil storage stability and shorten storage cycles. Therefore, efficient separation of oil-water emulsions has become a key issue that needs to be urgently addressed in the petroleum industry.

[0004] In order to solve the problem of oil-water emulsification, scientists have developed a variety of demulsifiers. Demulsifiers are chemicals that can destroy the emulsion layer at the oil-water interface and separate the oil-water mixture into two incompatible phases (oil phase and water phase). Demulsifiers achieve oil-water separation by changing the properties of the oil-water interface, reducing interfacial tension, and destroying the stability of the emulsion layer.

[0005] CN106565007A discloses a deoiling agent for produced water of ternary composite flooding, wherein the deoiling agent is prepared by reacting 2,5-pyridinediamine with formaldehyde and formic acid to generate an intermediate, and then reacting with sodium chlorododecanoate to generate a zwitterionic deoiling agent, wherein the molar ratio of the 2,5-pyridinediamine, formaldehyde, formic acid and sodium chlorododecanoate is 1:2.5-6:2.5-5.5:0.8-2.5, preferably 1:3:3:1.5. Although the invention has a relatively simple preparation process, strong adaptability, low cost, strong salt resistance and good deoiling effect, the agent uses pyridine in the preparation process, and the pyridine monomer is highly toxic, which will inevitably cause harm to the human body and the environment.

[0006] CN101113028A discloses a demulsifying purifying agent, characterized in that it is composed of the following raw materials by weight percentage: 2% - 68% of sewage purifier, 2% - 37% of polymeric ferric sulfate, 5% - 45% of polyaluminium chloride, 6% - 57% of anhydrous calcium chloride, and 19% - 47% of ferric trichloride; its preparation method is as follows: pour the sewage purifier, polymeric ferric sulfate and polyaluminium chloride into a mixer, then pour in anhydrous calcium chloride and add 50% of the total amount of water of these four raw materials, and stir thoroughly at a stirring speed of 60 revolutions per minute to ensure that the solid components are completely dissolved, and keep for 2 - 3 hours; then add ferric trichloride and continue to stir at a stirring speed of 50 - 80 revolutions per minute for half to 1 hour, and filter and pack into product packaging barrels after stopping for 6 - 10 hours. When the demulsifying agent of this invention is used for demulsification, the usage concentration of the agent is 300 - 500 mg / L, the dosage is large, the operation is cumbersome, and a large amount of scum will be generated. At the same time, a large amount of the agent remains in the water body, causing secondary pollution. Summary of the Invention

[0007] The present invention provides a demulsifying agent for eliminating the emulsified layer at the oil - water interface in the treatment of oil - field produced fluids and its preparation method in view of the deficiencies of the current existing technologies. The demulsifying agent of the present invention has the characteristics of simple synthesis process and high demulsification rate.

[0008] One of the purposes of the present invention is to disclose a demulsifying agent for eliminating the emulsified layer at the oil - water interface in the treatment of oil - field produced fluids. The molecular formula structural formula of the demulsifying agent is as follows:

[0009]

[0010] Wherein:

[0011] a = 20000 - 200000;

[0012] b = 2000 - 40000;

[0013] c = 4000 - 80000;

[0014] d = 2000 - 40000;

[0015] e = 4000 - 80000.

[0016] Preferably, the viscosity - average molecular weight of the demulsifying agent is 5000000 - 10000000.

[0017] Another purpose of the present invention is to disclose a preparation method of a demulsifying agent for eliminating the emulsified layer at the oil - water interface in the treatment of oil - field produced fluids. The specific steps of the preparation method are as follows:

[0018] (1)Add acrylamide, 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, allyl tributylphosphonium chloride, and deionized water into the first reactor, heat and dissolve them, and adjust the pH to 7-8 with sodium hydroxide solution;

[0019] (2)Purge the second reactor and the pipeline with nitrogen for 8-12 min, add allyl(diisopropylamino)dimethylsilane, butyl acrylate, deionized water, octylphenol polyoxyethylene ether-10, sodium dodecyl sulfate, and potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7-8 with sodium hydroxide solution;

[0020] (3)Add an initiator and sodium bisulfite into the second reactor, heat up to 50-60 °C, keep the temperature for reaction. When the viscosity starts to increase, pour the mixed solution in the first reactor into it, continue the reaction for 0.5-4 h, then heat up to 70-80 °C, keep the temperature for 1-2 h, and adjust the pH to 7-8 with sodium hydroxide solution to obtain a viscous liquid;

[0021] (4)Dry and granulate the viscous liquid to obtain a demulsifier.

[0022] In the present invention, preferably, based on 1 mole part of acrylamide, the amounts of 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, allyl tributylphosphonium chloride, allyl(diisopropylamino)dimethylsilane, and butyl acrylate are 0.1-0.2, 0.2-0.4, 0.1-0.2, and 0.2-0.4 mole parts respectively.

[0023] In the present invention, preferably, in step (1), the mass ratio of the deionized water to acrylamide is 6-8:1.

[0024] In the present invention, preferably, in step (2), the mass ratio of the deionized water, octylphenol polyoxyethylene ether-10, sodium dodecyl sulfate, potassium dihydrogen phosphate to acrylamide is 3-4:0.05-0.1:0.02-0.05:0.05-0.1:1.

[0025] In the present invention, preferably, in step (3), the initiator is one of sodium persulfate, potassium persulfate, and ammonium persulfate, and the mass ratio of the initiator, sodium bisulfite to acrylamide is 0.05-0.1:0.02-0.05:1.

[0026] The synthesis reaction equation of the demulsifier of the present invention is as follows:

[0027]

[0028]

[0029] The demulsifier of the present invention is a polymer demulsifier with polyethylene as the main chain and various long-chain functional groups as the side chains. The polyacrylamide as the main body can adsorb suspended particles and colloidal substances in water to form larger flocs. These flocs can entrap and sweep droplets during the sedimentation process, thus accelerating the oil-water separation; polyester molecules adsorb at the oil-water interface, destroying the stability of the interface film to achieve the effect of flocculation and demulsification; cationic quaternary phosphonium salts and imidazole salts neutralize the charges with negatively charged emulsion droplets, compress and destroy the double electric layer, weaken the strength of the interface film, causing the emulsion droplets to collide and coalesce with each other, making the oil droplets lose the repulsive force and aggregate with each other, and making the tiny oil droplets aggregate and release to form oil beads with larger particle sizes, thus achieving the purpose of demulsification; fluoroalkanes and silane molecules form a hydrophobic film at the oil-water interface, destroying the original emulsion film, and at the same time promoting droplet coalescence by reducing the interfacial tension; polyester molecules adsorb at the oil-water interface, destroying the stability of the interface film to achieve the effect of flocculation and demulsification.

[0030] The present invention has the following advantages and beneficial effects compared with the prior art:

[0031] The demulsifier of the present invention has good demulsification effect. For the emulsified oil in the gathering and transportation oil-water transition zone with a concentration of 32000 mg / L, when the use concentration is 50 mg / L, the water separation amount of 100 ml of emulsion reaches 91 ml or more in 90 min. The water phase after demulsification is clear, the oil content is not higher than 72 mg / L, and the oil-water interface is clear. Detailed implementation mode

[0032] The present invention will be further described in detail below with reference to specific examples and data. It should be understood that these examples are only for illustrating the present invention and do not limit the scope of the present invention in any way.

[0033] Example 1

[0034] (1) Add 0.5 mol of acrylamide, 0.05 mol of 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.2 mol of allyl tributyl phosphonium chloride, and 213 g of deionized water to the first reactor, heat and dissolve, and adjust the pH to 7-8 with sodium hydroxide solution;

[0035] (2) Purge the second reactor and pipelines with nitrogen for 10 min, add 0.05 mol of allyl(diisopropylamino)dimethylsilane, 0.2 mol of butyl acrylate, 142 g of deionized water, 3.55 g of octylphenol polyoxyethylene ether-10, 1.78 g of sodium dodecyl sulfate, and 3.55 g of potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7-8 with sodium hydroxide solution;

[0036] (3) Add 3.55 g of sodium persulfate and 1.78 g of sodium bisulfite to the second reactor, heat up to 50 °C, keep the temperature for reaction. When the viscosity starts to increase, pour the mixed liquid in the first reactor into it, continue the reaction for 0.5 h, then heat up to 80 °C and keep the temperature for 1 h. Adjust the pH to 7 - 8 with sodium hydroxide solution to obtain a viscous liquid;

[0037] (4) Dry and granulate the viscous liquid to obtain a demulsifier.

[0038] Example 2

[0039] (1) Add 0.5 mol of acrylamide, 0.06 mol of 1 - allyl - 3 - methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.19 mol of allyl tributylphosphonium chloride, and 228 g of deionized water to the first reactor, heat and dissolve, and adjust the pH to 7 - 8 with sodium hydroxide solution;

[0040] (2) Purge the second reactor and the pipeline with nitrogen for 8 min, add 0.05 mol of allyl(diisopropylamino)dimethylsilane, 0.18 mol of butyl acrylate, 133 g of deionized water, 3.13 g of octylphenol polyoxyethylene ether - 10, 1.58 g of sodium dodecyl sulfate, and 3.05 g of potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7 - 8 with sodium hydroxide solution;

[0041] (3) Add 3.14 g of sodium persulfate and 1.52 g of sodium bisulfite to the second reactor, heat up to 60 °C, keep the temperature for reaction. When the viscosity starts to increase, pour the mixed liquid in the first reactor into it, continue the reaction for 0.5 h, then heat up to 80 °C and keep the temperature for 2 h. Adjust the pH to 7 - 8 with sodium hydroxide solution to obtain a viscous liquid;

[0042] (4) Dry and granulate the viscous liquid to obtain a demulsifier.

[0043] Example 3

[0044] (1) Add 0.5 mol of acrylamide, 0.07 mol of 1 - allyl - 3 - methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.18 mol of allyl tributylphosphonium chloride, and 237 g of deionized water to the first reactor, heat and dissolve, and adjust the pH to 7 - 8 with sodium hydroxide solution;

[0045] (2) Purge the second reactor and the pipeline with nitrogen for 10 min, add 0.06 mol of allyl(diisopropylamino)dimethylsilane, 0.16 mol of butyl acrylate, 132 g of deionized water, 2.83 g of octylphenol polyoxyethylene ether - 10, 1.2 g of sodium dodecyl sulfate, and 2.75 g of potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7 - 8 with sodium hydroxide solution;

[0046] (3) Add 3.05 g of sodium persulfate and 1.33 g of sodium bisulfite to the second reactor, heat up to 50 °C, keep the temperature for reaction. When the viscosity starts to rise, pour the mixed liquid in the first reactor into it, continue the reaction for 4 h, then heat up to 80 °C and keep the temperature for 1.6 h. Adjust the pH to 7 - 8 with sodium hydroxide solution to obtain a viscous liquid;

[0047] (4) Dry and granulate the viscous liquid to obtain a demulsifier.

[0048] Example 4

[0049] (1) Add 0.5 mol of acrylamide, 0.08 mol of 1 - allyl - 3 - methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.16 mol of allyl tributylphosphonium chloride, and 243 g of deionized water to the first reactor, heat and dissolve, and adjust the pH to 7 - 8 with sodium hydroxide solution;

[0050] (2) Purge the second reactor and the pipeline with nitrogen for 9 min, add 0.07 mol of allyl(diisopropylamino)dimethylsilane, 0.15 mol of butyl acrylate, 125 g of deionized water, 2.55 g of octylphenol polyoxyethylene ether - 10, 1.08 g of sodium dodecyl sulfate, and 2.43 g of potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7 - 8 with sodium hydroxide solution;

[0051] (3) Add 3.15 g of potassium persulfate and 1.06 g of sodium bisulfite to the second reactor, heat up to 55 °C, keep the temperature for reaction. When the viscosity starts to rise, pour the mixed liquid in the first reactor into it, continue the reaction for 2 h, then heat up to 76 °C and keep the temperature for 1 h. Adjust the pH to 7 - 8 with sodium hydroxide solution to obtain a viscous liquid;

[0052] (4) Dry and granulate the viscous liquid to obtain a demulsifier.

[0053] Example 5

[0054] (1) Add 0.5 mol of acrylamide, 0.08 mol of 1 - allyl - 3 - methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.14 mol of allyl tributylphosphonium chloride, and 263 g of deionized water to the first reactor, heat and dissolve, and adjust the pH to 7 - 8 with sodium hydroxide solution;

[0055] (2) Purge the second reactor and the pipeline with nitrogen for 10 min, add 0.08 mol of allyl(diisopropylamino)dimethylsilane, 0.14 mol of butyl acrylate, 122 g of deionized water, 2.15 g of octylphenol polyoxyethylene ether - 10, 0.92 g of sodium dodecyl sulfate, and 2.1 g of potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7 - 8 with sodium hydroxide solution;

[0056] (3) Add 3.25 g of potassium persulfate and 0.78 g of sodium bisulfite to the second reactor, heat up to 58 °C, keep the temperature for reaction. When the viscosity starts to increase, pour the mixed solution in the first reactor into it, continue the reaction for 1 h, then heat up to 70 °C and keep the temperature for 1.2 h. Adjust the pH to 7 - 8 with sodium hydroxide solution to obtain a viscous liquid.

[0057] (4) Dry and granulate the viscous liquid to obtain a demulsifier.

[0058] Example 6

[0059] (1) Add 0.5 mol of acrylamide, 0.09 mol of 1 - allyl - 3 - methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.12 mol of allyl tributylphosphonium chloride, and 278 g of deionized water to the first reactor, heat to dissolve, and adjust the pH to 7 - 8 with sodium hydroxide solution.

[0060] (2) Purge the second reactor and the pipeline with nitrogen for 11 min, add 0.09 mol of allyl(diisopropylamino)dimethylsilane, 0.12 mol of butyl acrylate, 110 g of deionized water, 1.95 g of octylphenol polyoxyethylene ether - 10, 0.78 g of sodium dodecyl sulfate, and 1.98 g of potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7 - 8 with sodium hydroxide solution.

[0061] (3) Add 1.78 g of ammonium persulfate and 0.71 g of sodium bisulfite to the second reactor, heat up to 60 °C, keep the temperature for reaction. When the viscosity starts to increase, pour the mixed solution in the first reactor into it, continue the reaction for 1 h, then heat up to 72 °C and keep the temperature for 2 h. Adjust the pH to 7 - 8 with sodium hydroxide solution to obtain a viscous liquid.

[0062] (4) Dry and granulate the viscous liquid to obtain a demulsifier.

[0063] Example 7

[0064] (1) Add 0.5 mol of acrylamide, 0.1 mol of 1 - allyl - 3 - methylimidazolium bis(trifluoromethanesulfonyl)imide, 0.1 mol of allyl tributylphosphonium chloride, and 284 g of deionized water to the first reactor, heat to dissolve, and adjust the pH to 7 - 8 with sodium hydroxide solution.

[0065] (2) Purge the second reactor and the pipeline with nitrogen for 12 min, add 0.1 mol of allyl(diisopropylamino)dimethylsilane, 0.1 mol of butyl acrylate, 106.5 g of deionized water, 1.78 g of octylphenol polyoxyethylene ether - 10, 0.71 g of sodium dodecyl sulfate, and 1.78 g of potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7 - 8 with sodium hydroxide solution.

[0066] (3) Add 2.55 g of ammonium persulfate and 1.28 g of sodium bisulfite to the second reactor, heat up to 53 °C, and keep the temperature for reaction. When the viscosity starts to increase, pour the mixed liquid in the first reactor into it, continue the reaction for 4 h, then heat up to 70 °C and keep the temperature for another 1.5 h. Adjust the pH to 7 - 8 with sodium hydroxide solution to obtain a viscous liquid;

[0067] (4) Dry and granulate the viscous liquid to obtain a demulsifier.

[0068] Performance evaluation of the demulsifier in Example 8

[0069] Take the crude oil from the oil - water transition zone in the crude oil storage tank of a production plant in Shengli Oilfield to test the demulsification performance of the demulsifier of the present invention (Examples 1 - 7). The oil content of the emulsified oil in the oil - water transition zone is 32000 mg / L. The evaluation method refers to SY / T 5281 - 2000 "Testing Method for the Performance of Crude Oil Demulsifiers". The experimental temperature is 60 °C, and the dosing concentrations are 30 and 50 mg / L. Use the SP - 169 crude oil demulsifier from Hai'an Petrochemical Factory in Jiangsu Province for comparative experiments. The test results are shown in Table 1.

[0070] Table 1 Experimental results of crude oil demulsifiers

[0071]

[0072] It can be seen from Table 1 that:

[0073] (1) For the crude oil in the oil - water transition zone of the crude oil storage tank of the production plant with an oil content of 32000 mg / L, when the demulsifier of the present invention (Examples 1 - 7) is used at a concentration of 30 mg / L, the dehydration volume of 100 ml of the emulsion reaches 89 ml or more in 90 min. The water phase after demulsification is clear, the oil content is not higher than 76 mg / L, and the oil - water interface is clear; while for the SP - 169 crude oil demulsifier from Hai'an Petrochemical Factory in Jiangsu Province as the comparative example, the dehydration volume in 90 min is 70 ml, the oil - water interface after demulsification is blurred, the oil content is 250 mg / L, and the demulsification effect is significantly lower than that of the present invention;

[0074] (2) For the crude oil in the oil - water transition zone of the crude oil storage tank of the production plant with an oil content of 32000 mg / L, when the demulsifier of the present invention (Examples 1 - 7) is used at a concentration of 50 mg / L, the dehydration volume of 100 ml of the emulsion reaches 91 ml or more in 90 min. The water phase after demulsification is clear, the oil content is not higher than 72 mg / L, and the oil - water interface is clear; while for the SP - 169 crude oil demulsifier from Hai'an Petrochemical Factory in Jiangsu Province as the comparative example, the dehydration volume in 90 min is 82 ml, the oil - water interface after demulsification is clear, the oil content is 102 mg / L, and the demulsification effect is significantly lower than that of the present invention.

[0075] 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 technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A preparation method of a demulsifier for eliminating the emulsified layer at the oil-water interface in the treatment of oilfield produced fluid, characterized in that, The specific steps of the preparation method are as follows: (1) Add acrylamide, 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, allyl tributylphosphonium chloride, and deionized water into the first reactor, heat and dissolve, adjust the pH to 7-8 with sodium hydroxide solution. The mass ratio of the deionized water to acrylamide is 6-8:1; (2) Purge the second reactor and pipeline with nitrogen for 8-12 min, add allyl(diisopropylamino)dimethylsilane, butyl acrylate, deionized water, octylphenol polyoxyethylene ether-10, sodium dodecyl sulfate, and potassium dihydrogen phosphate, stir to form an emulsion, and adjust the pH to 7-8 with sodium hydroxide solution. The mass ratio of the deionized water, octylphenol polyoxyethylene ether-10, sodium dodecyl sulfate, and potassium dihydrogen phosphate to acrylamide is 3-4: 0.05-0.1：0.02-0.05：0.05-0.1：1； (3) Add an initiator and sodium bisulfite into the second reactor, heat up to 50-60 °C, keep the temperature for reaction. When the viscosity starts to increase, pour the mixed solution in the first reactor into it, continue the reaction for 0.5-4 h, then heat up to 70-80 °C, keep the temperature for 1-2 h, and adjust the pH to 7-8 with sodium hydroxide solution to obtain a viscous liquid. The mass ratio of the initiator, sodium bisulfite to acrylamide is 0.05-0.1:0.02-0.05:1; (4) Dry and granulate the viscous liquid to obtain a demulsifier; Based on 1 mole part of acrylamide, the dosages of 1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, allyl tributylphosphonium chloride, allyl(diisopropylamino)dimethylsilane, and butyl acrylate are 0.1-0.2, 0.2-0.4, 0.1-0.2, and 0.2-0.4 mole parts respectively.

2. The preparation method of a demulsifier for eliminating the emulsified layer at the oil-water interface in the treatment of oilfield produced fluid according to claim 1, characterized in that, The initiator is one of sodium persulfate, potassium persulfate, and ammonium persulfate.

3. A demulsifier for eliminating the emulsified layer at the oil-water interface in the treatment of oilfield produced fluids, characterized in that, The molecular formula structural formula of the demulsifier is as follows: Wherein: a=20000-200000； b=2000-40000； c=4000-80000； d=2000-40000； e=4000-80000。 4. The demulsifier according to claim 3, wherein, The viscosity-average molecular weight of the demulsifier is 5,000,000-10,000,000.

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