Macromolecular demulsifier as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to a macromolecular demulsifier as well as a preparation method and application thereof. The preparation method comprises the following steps: adding N-methylallylamine and a catalyst into a high-pressure reaction kettle, purging the reaction kettle with nitrogen, vacuumizing, slowly introducing ethylene oxide, heating, and carrying out heat preservation reaction; the preparation method comprises the following steps: adding distilled water, adjusting the pH value to 7-8 by using hydrochloric acid, adding (3-acryloyloxypropyl) tri (trimethylsiloxy) silane, methacryloyloxyethyl trimethyl ammonium chloride, buffer salt and lauryl sodium sulfate, and adjusting the pH value to 7-8; and adding an initiator, carrying out heat preservation reaction, cooling to below 40 DEG C to obtain a viscous liquid, filtering and drying to obtain the product demulsifier. The demulsifier disclosed by the invention has a relatively high demulsification rate, and when the use concentrations are respectively 20 mg / L and 40 mg / L, the dehydration rates can respectively reach 92.9% and 95.6%; the sterilizing agent disclosed by the invention has a relatively high sterilizing rate, and the sterilizing rate can reach 100% when the use concentration is 10mg / L.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil exploitation, and particularly relates to a high-molecular demulsifier as well as a preparation method and application thereof. BACKGROUND

[0002] In many industrial fields such as oil exploitation, oil refining and chemical industry, sewage treatment, food processing and mechanical lubrication, stable emulsion systems, especially oil-in-water (O / W) or water-in-oil (W / O) emulsions, are often encountered. Although the formation of these emulsions is sometimes required by the process, in most separation, purification or environmental protection links, it is necessary to efficiently destroy them to achieve rapid and thorough separation of the oil and water phases.

[0003] Demulsifiers are key chemicals for realizing this process. The demulsifiers traditionally used are mostly low-molecular surfactants (such as polyether type, alcohol type, acid salt type, etc.), which, by adsorbing on the oil-water interface, reduce the interfacial tension and destroy the stability of the interfacial film, thereby achieving the purpose of demulsification. However, such low-molecular demulsifiers generally have the following limitations: limited demulsification efficiency: for some emulsions with extremely high stability and large interfacial film strength, especially in the middle and late stages of oilfield exploitation, the composition of produced liquid is complex and emulsification is serious, and the traditional demulsifiers often have large dosage, slow dehydration speed and unclearly separated water. Poor adaptability: the properties of crude oil, water quality and exploitation process (such as after chemical flooding, polymer flooding) of different oilfields differ greatly, leading to variable characteristics of emulsions. The low-molecular demulsifiers with single structure are not strong in universality and are difficult to cope with complex and variable working conditions.

[0004] In order to overcome these shortcomings, high-molecular demulsifiers have gradually become the focus of research and application. High-molecular demulsifiers have the characteristics of large molecular weight, strong designability of molecular structure, ability to form stronger adsorption film on the interface or stronger flocculation and coalescence, and exhibit potential advantages of high efficiency, rapidness and strong adaptability.

[0005] CN106565007 discloses an oil removal agent for produced water of ternary combination flooding, which is prepared by reacting 2,5-pyridine diamine with formaldehyde and formic acid to generate an intermediate, and then reacting the intermediate with sodium chlorododecanoate to generate an amphoteric ion type oil removal agent. The molar ratio of 2,5-pyridine diamine, formaldehyde, formic acid and sodium chlorododecanoate is 1:2.5-6:2.5-5.5:0.8-2.5, and is preferably 1:3:3:1.5. The oil removal agent of the invention has the characteristics of simple preparation, strong adaptability, low cost, strong salt resistance and good oil removal effect, and the salt resistance reaches 2.3 x 10 4 mg / L, and the oil removal rate of the produced water of ternary combination flooding reaches 97% or more. The recovered oil produced by separation does not affect subsequent crude oil dehydration, and therefore the invention can be widely applied to the oil removal process of produced water of ternary combination flooding. However, pyridine is used in the synthesis of the product of the invention, which has high toxicity and is easy to cause environmental pollution.

[0006] CN 109575984 A relates to a crude oil demulsifier for normal and low temperature, which is composed of 10-50% of siloxane polyether with viscosity of 200-300 cSt, HLB value of 7-10, and closed flash point of more than 60℃, and 50-90% of one or more mixtures as solvents. The siloxane polyether in the composition of the crude oil demulsifier has different structures and molecular weight distribution, has high efficient oil-water demulsification effect, and the siloxane has low surface tension, low cohesive energy and low temperature sensitivity, so that the demulsification can be realized at low temperature of 30℃, and the addition amount is reduced by more than 50% than using polyether surfactant alone, the dehydration rate is fast, the demulsification effect is good, and the comprehensive cost is reduced. However, the dehydration rate of the crude oil is only 40% in 120 min, the effect is poor, and the dehydration effect needs to be improved. SUMMARY

[0007] The present application provides a high molecular weight demulsifier, a preparation method and application thereof, and the demulsifier has the characteristics of demulsification and sterilization.

[0008] The first object of the present application is to provide a preparation method of a high molecular weight demulsifier, which comprises the following steps: (1) adding N-methylallylamine and a catalyst into a high-pressure reaction kettle, purging the reaction kettle with nitrogen, vacuumizing, slowly introducing ethylene oxide, and heating and keeping warm; (2) adding distilled water, adjusting pH to 7-8 with hydrochloric acid, adding (3-acryloyloxypropyl) tris(trimethylsiloxy) silane, methacryloyloxyethyl trimethyl ammonium chloride, buffer salt, and sodium dodecyl sulfate, adjusting pH to 7-8 with sodium hydroxide solution, and stirring uniformly; (3) purging the reactor with nitrogen, adding an initiator, keeping warm, cooling to below 40℃, obtaining a viscous liquid, adding ethanol, precipitating a solid, filtering and drying to obtain the product demulsifier.

[0009] Based on 1 mole of N-methylallylamine, the amounts of ethylene oxide, (3-acryloyloxypropyl) tris(trimethylsiloxy) silane, and methacryloyloxyethyl trimethyl ammonium chloride are 2-50 moles, 0.1-0.2 moles, and 0.2-0.4 moles, respectively.

[0010] Preferably, in step (1), the weight ratio of the catalyst to N-methylallylamine is 0.02-0.06:1, and the catalyst is one of sodium hydroxide and potassium hydroxide.

[0011] Preferably, in step (1), the heating and keeping warm temperature is 80-130℃, and the time is 0.5-4h.

[0012] Preferably, in step (2), the weight ratio of distilled water, buffer salt, sodium dodecyl sulfate and N-methyl allylamine is 10-40:0.1-0.5:0.2-0.5:1.

[0013] Preferably, the buffer salt is one of sodium dihydrogen phosphate and potassium dihydrogen phosphate.

[0014] Preferably, in step (3), the initiator is a mixed solution of persulfate and sodium bisulfite, wherein the concentration of persulfate is 8-10wt%, the concentration of sodium bisulfite is 3-5wt%, and the weight ratio of initiator to N-methyl allylamine is 1-5:1.

[0015] Preferably, the persulfate is one of potassium persulfate, ammonium persulfate and sodium persulfate.

[0016] Preferably, in step (3), the reaction temperature is 60-90℃, and the reaction time is 1-4h.

[0017] The synthesis reaction equation of the high molecular demulsifier of the present application is as follows:

[0018]

[0019]

[0020] Another object of the present application is to provide a high molecular demulsifier, and the molecular formula structure of the demulsifier is as follows: , Wherein: x=3000-30000; y=300-6000; z=600-12000; n=2-50.

[0021] The viscosity average molecular weight of the demulsifier is 2000000-3000000.

[0022] The third object of the present application discloses the application of the above demulsifier in oilfield produced liquid treatment.

[0023] The demulsifier provided by the application is a high-molecular surfactant, which is polymerized from three functional monomers and has the functions of water-phase oil removal, oil-phase demulsification and sterilization. The urethane polyether can capture a large amount of small oil droplets, has high flexibility, can easily rotate internally, increases the collision opportunities of the oil droplets, and makes the oil droplets easy to coalesce and float to achieve the demulsification purpose. The silicone demulsifier is efficiently adsorbed on the oil-water interface due to its unique surface activity, low surface tension and super hydrophobicity, replaces or destroys the stable interface film formed by the original natural emulsifier, promotes the collision, coalescence and sedimentation of small water droplets, and finally realizes the separation of oil and water. The quaternary ammonium salt has positive electricity and can neutralize the negatively charged oil droplets, compress and destroy the double electric layer, weaken the interface film strength, make the emulsion droplets collide and coalesce with each other, make the oil droplets lose the repulsion between each other and gather together, make the small oil droplets gather and release to form large oil droplets, and thus achieve the demulsification purpose. The quaternary ammonium salt can destroy the cell membrane / cell wall structure of microorganisms due to its unique cationic surface activity, cause the leakage of cell contents, protein denaturation and enzyme system inactivation, and thus kill the microorganisms.

[0024] Compared with the prior art, the application has the following advantages and beneficial effects: (1) The application has high demulsification rate, and the dehydration rates can reach 92.9% and 95.6% when the use concentrations are 20 mg / L and 40 mg / L respectively. (2) The application has high sterilization rate, and the sterilization rate can reach 100% when the use concentration is 10 mg / L. DETAILED DESCRIPTION

[0025] The technical scheme of the application will be further described below in combination with examples: Example 1 (1) 0.2 mol of N-methylallylamine and 0.28 g of sodium hydroxide are added into a high-pressure reaction kettle, the reaction kettle is purged with nitrogen, vacuumized, slowly purged with 0.4 mol of ethylene oxide, heated to 80℃, and kept for 0.5 h; (2) 142 g of distilled water is added, the pH is adjusted to 7-8 by using hydrochloric acid, 0.02 mol of (3-acryloyloxypropyl) tris(trimethylsiloxy) silane, 0.04 mol of methyl acryloyloxyethyl trimethyl ammonium chloride, 1.42 g of potassium dihydrogen phosphate and 2.84 g of sodium dodecyl sulfate are added, the pH is adjusted to 7-8 by using sodium hydroxide solution, and the mixture is stirred uniformly; (3) the reaction kettle is purged with nitrogen, 14.2 g of initiator is added, the initiator contains 10 wt% of sodium persulfate and 5 wt% of sodium bisulfite, heated to 60℃, kept for 4 h, cooled to below 40℃, a viscous liquid is obtained, ethanol is added, solid is precipitated, filtration and drying are performed, and the product demulsifier is obtained.

[0026] Example 2 (1) In a high-pressure reactor, 0.2 mol of N-methylallylamine and 0.41 g of sodium hydroxide were added, the reactor was purged with nitrogen, vacuumized, 1 mol of ethylene oxide was slowly introduced, heated to 90°C, and reacted for 1 h; (2) 216 g of distilled water was added, the pH was adjusted to 7-8 with hydrochloric acid, 0.025 mol of (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 0.05 mol of methacryloyloxyethyltrimethylammonium chloride, 2.88 g of potassium dihydrogen phosphate, and 3.69 g of sodium dodecyl sulfate were added, the pH was adjusted to 7-8 with sodium hydroxide solution, and stirred uniformly; (3) The reactor was purged with nitrogen, 27.3 g of initiator was added, the initiator contained 9 wt% of sodium persulfate and 4 wt% of sodium bisulfite, heated to 70°C, reacted for 3 h, cooled to below 40°C, a viscous liquid was obtained, ethanol was added, solid was precipitated, filtered and dried to obtain the product demulsifier.

[0027] Example 3 (1) In a high-pressure reactor, 0.2 mol of N-methylallylamine and 0.56 g of sodium hydroxide were added, the reactor was purged with nitrogen, vacuumized, 2 mol of ethylene oxide was slowly introduced, heated to 90°C, and reacted for 4 h; (2) 318 g of distilled water was added, the pH was adjusted to 7-8 with hydrochloric acid, 0.03 mol of (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 0.05 mol of methacryloyloxyethyltrimethylammonium chloride, 4.42 g of potassium dihydrogen phosphate, and 4.84 g of sodium dodecyl sulfate were added, the pH was adjusted to 7-8 with sodium hydroxide solution, and stirred uniformly; (3) The reactor was purged with nitrogen, 40.7 g of initiator was added, the initiator contained 8 wt% of potassium persulfate and 3 wt% of sodium bisulfite, heated to 90°C, reacted for 1 h, cooled to below 40°C, a viscous liquid was obtained, ethanol was added, solid was precipitated, filtered and dried to obtain the product demulsifier.

[0028] Example 4 (1) In a high-pressure reactor, 0.2 mol of N-methylallylamine and 0.62 g of sodium hydroxide were added, the reactor was purged with nitrogen, vacuumized, 4 mol of ethylene oxide was slowly introduced, heated to 110°C, and reacted for 2 h; (2) 406 g of distilled water was added, the pH was adjusted to 7-8 with hydrochloric acid, 0.03 mol of (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 0.06 mol of methacryloyloxyethyltrimethylammonium chloride, 7.1 g of potassium dihydrogen phosphate, and 5.16 g of sodium dodecyl sulfate were added, the pH was adjusted to 7-8 with sodium hydroxide solution, and stirred uniformly; (3) Purge the reactor with nitrogen, add 50.1g of initiator containing 9wt% sodium persulfate and 4wt% sodium bisulfite, heat to 70°C, keep the reaction at 70°C for 2 hours, cool down to below 40°C to obtain a viscous liquid, add ethanol to precipitate the solid, filter and dry to obtain the product demulsifier.

[0029] Example 5 (1) Add 0.2 mol N-methylallylamine and 0.74 g potassium hydroxide to a high-pressure reactor, purge the reactor with nitrogen, evacuate, slowly introduce 6 mol ethylene oxide, heat to 120°C, and keep the reaction at this temperature for 4 h. (2) Add 500g of distilled water, adjust the pH to 7-8 with hydrochloric acid, add 0.035mol of (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 0.07mol of methacryloyloxyethyltrimethylammonium chloride, 6.2g of sodium dihydrogen phosphate, and 6.33g of sodium dodecyl sulfate, adjust the pH to 7-8 with sodium hydroxide solution, and stir well; (3) Purge the reactor with nitrogen, add 58g of initiator containing 10wt% ammonium persulfate and 4wt% sodium bisulfite, heat to 80℃, keep the reaction at this temperature for 2h, cool down to below 40℃ to obtain a viscous liquid, add ethanol, precipitate the solid, filter and dry to obtain the product demulsifier.

[0030] Example 6 (1) Add 0.2 mol N-methylallylamine and 0.85 g potassium hydroxide to a high-pressure reactor, purge the reactor with nitrogen, evacuate, slowly introduce 10 mol ethylene oxide, heat to 130 °C, and keep the reaction at this temperature for 4 h. (2) Add 568g of distilled water, adjust the pH to 7-8 with hydrochloric acid, add 0.04mol of (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 0.08mol of methacryloyloxyethyltrimethylammonium chloride, 5.62g of sodium dihydrogen phosphate, and 7.1g of sodium dodecyl sulfate, adjust the pH to 7-8 with sodium hydroxide solution, and stir evenly; (3) Purge the reactor with nitrogen, add 71g of initiator containing 10wt% ammonium persulfate and 5wt% sodium bisulfite, heat to 80℃, keep the reaction at 80℃ for 3h, cool down to below 40℃ to obtain a viscous liquid, add ethanol, precipitate solid, filter and dry to obtain the product demulsifier.

[0031] Example 7 Evaluation of demulsification effect Water sample to be tested: Heavy oil emulsion from a joint station of an oil production plant in Shengli Oilfield, with an oil content of 250,000 mg / L and a crude oil viscosity of 8,600 mPa.s.

[0032] Evaluation method: Refer to SY / T 5280-2018 "General Technical Conditions for Crude Oil Demulsifiers". Demulsifier concentration: 20, 40 mg / L.

[0033] Test indicators: dehydration rate, oil content in the dehydrated water, and clarity of the oil-water interface.

[0034] A comparative experiment was conducted using crude oil demulsifier from Tianjin Xiongguan Technology Development Co., Ltd., and the results are shown in Table 1.

[0035] Table 1 Results of demulsification experiment

[0036] As can be seen from Table 1, the demulsifier of the present invention (Examples 1-7), when used at concentrations of 20 and 40 mg / L, achieved dehydration rates of over 90% and 92% respectively for heavy oil emulsions with a crude oil viscosity of 8600 mPa·s and an oil content of 250000 mg / L, with the highest rates reaching 92.9% and 95.6% respectively; while the dehydration rates of the comparative examples were 69% and 80%, significantly lower than those of the present invention.

[0037] Example 8 Evaluation of sterilization effect Water sample to be tested: Water sample after oil-water separation from a joint station in Shengli Oilfield, with a mineralization of 18000 mg / L. 10 and 20 mg / L of the demulsifier of this invention (Examples 1-6) were added to the above water sample. After standing for 1 hour, the total bacterial count was tested using the plate coating method. A blank sample was also prepared, and the sterilization rate was calculated. Glutaraldehyde was used as a comparative experiment.

[0038] The culture medium formula and preparation method for the plates are as follows: peptone, 2g; sodium lactate, 2g; magnesium sulfate, 1g; ammonium chloride, 1g; potassium dihydrogen phosphate, 0.5g; calcium chloride, 0.05g; sodium chloride, 5g; ferrous sulfate, 0.005g; yeast extract, 0.5g; agar, 20g; distilled water, 1000ml. Autoclave at 121℃ for 20 minutes.

[0039] Culture method: static culture at 40℃. The experimental results are shown in Table 2.

[0040] Table 2. Results of sterilization experiment (sterilization rate, %) 10 mg / L, 20 mg / L, Example 1 95 99 Example 2 96 99 Example 3 98 100 Example 4 99 100 Example 5 100 100 Example 6 100 100 Comparative Example 74 90 As can be seen from Table 2, the demulsifier of the present invention (Examples 1-6) achieved a sterilization rate of 95% or higher and 99% or higher, respectively, with a maximum of 100%, when used at concentrations of 10 and 20 mg / L, respectively; while the sterilization rates of the comparative examples were 70% and 90%, respectively. These are significantly lower than those of the present invention.

[0041] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. 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, and these simple modifications all fall within the protection scope of the present invention.

[0042] 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.

[0043] 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.

Claims

1. A method for preparing a polymeric demulsifier, characterized in that, The preparation method includes the following steps: (1) Add N-methylallylamine and catalyst to the high-pressure reactor, purge the reactor with nitrogen, evacuate, slowly introduce ethylene oxide, and heat and keep the reaction at the temperature; (2) Add distilled water, adjust the pH to 7-8 with hydrochloric acid, add (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, methacryloyloxyethyltrimethylammonium chloride, buffer salt, sodium dodecyl sulfate, adjust the pH to 7-8 with sodium hydroxide solution, and stir well; (3) Purge the reactor with nitrogen, add initiator, keep the reaction at the temperature, cool down to below 40°C to obtain a viscous liquid, add ethanol, precipitate solid, filter and dry to obtain the product demulsifier; Based on 1 mole of N-methylallylamine, the amounts of ethylene oxide, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, and methacryloyloxyethyltrimethylammonium chloride are 2-50 moles, 0.1-0.2 moles, and 0.2-0.4 moles, respectively.

2. The preparation method according to claim 1, characterized in that, In step (1), the weight ratio of the catalyst to N-methylallylamine is 0.02-0.06:1, and the catalyst is either sodium hydroxide or potassium hydroxide.

3. The preparation method according to claim 1, characterized in that, In step (1), the heating and heat preservation reaction temperature is 80-130℃ and the time is 0.5-4h; in step (3), the heat preservation reaction temperature is 60-90℃ and the time is 1-4h.

4. The preparation method according to claim 1, characterized in that, In step (2), the weight ratio of distilled water, buffer salt, sodium dodecyl sulfate, and N-methylallylamine is 10-40: 0.1-0.5：0.2-0.5：1。 5. The preparation method according to claim 1, characterized in that, The buffer salt is one of sodium dihydrogen phosphate or potassium dihydrogen phosphate.

6. The preparation method according to claim 1, characterized in that, In step (3), the initiator is a mixed solution of persulfate and sodium bisulfite, wherein the concentration of persulfate is 8-10 wt%, the concentration of sodium bisulfite is 3-5 wt%, and the weight ratio of initiator to N-methylallylamine is 1-5:

1.

7. The preparation method according to claim 6, characterized in that, The persulfate mentioned is one of potassium persulfate, ammonium persulfate, and sodium persulfate.

8. The demulsifier prepared by the preparation method according to any one of claims 1-7.

9. The demulsifier according to claim 8, characterized in that, The molecular formula of the demulsifier is as follows: ， in: x=3000-30000； y=300-6000； z=600-12000； n=2-50； The viscosity-average molecular weight of the demulsifier is 2,000,000-3,000,000.

10. The application of the demulsifier according to claim 8 or 9 in the treatment of produced fluids in oilfields.

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