CN110240675A - Demulsifier and preparation method thereof and application in demulsification of produced fluid from binary composite flooding - Google Patents

Abstract

The invention relates to the field of demulsification of produced fluid from binary composite flooding, in particular to a demulsifier and a preparation method thereof, and the application of produced fluid from binary composite flooding in demulsification. The preparation method of the demulsifier comprises: (1) reacting an initiator, ethylene oxide and propylene oxide to obtain a block polyether in the presence of an etherification catalyst; (2) in the presence of an esterification catalyst and a polymerization inhibitor Under the following conditions, the block polyether and the unsaturated carboxylate are subjected to a transesterification reaction, so that the end of the block polyether has an unsaturated carboxylate, and then the alcohol is distilled off under reduced pressure to obtain an esterified product; (3) The esterification product is polymerized with a cationically unsaturated monomer in the presence of a free radical initiator and a polymerization assistant. The demulsifier provided by the invention can obtain excellent demulsification effect on the produced fluid of binary composite flooding at a lower dosage.

Description

Demulsifier and preparation method thereof and application in demulsification of produced fluid from binary composite flooding

technical field

The invention relates to the field of demulsification of produced fluid from binary composite flooding, in particular to a demulsifier and a preparation method thereof and its application in the demulsification of produced fluid from binary composite flooding.

Background technique

Binary composite flooding refers to the technology of using polymers and surfactants to enhance oil recovery. Due to the use of more efficient surfactants, polymers and improved reservoir models, the role of binary composite flooding has received more and more attention . But it follows that demulsification is very difficult due to the high concentration of surfactants and polymers in the produced fluid of binary composite flooding.

People try traditional non-ionic demulsifiers to break demulsifiers, but the effect is not ideal, and the dosage of conventional crude oil demulsifiers is tens to hundreds of times larger. , but it is still not ideal for the demulsification of the produced fluid in the binary compound flooding of heavy oil. Aluminium salts and traditional cationic polymer flocculants are also added, but they produce a sticky precipitate at the bottom of the oil phase and contaminate the oil phase.

CN1621123A reported the reaction of block polyether with nucleating nanomaterials containing aluminum salt or ethyl silicate to prepare demulsifier with nuclear membrane structure, which is used for demulsification of chemical flooding produced fluid, but the demulsifier containing silicon remains in the oil phase It may have an impact on subsequent processing; CN102233249A and CN104479731A use dendritic polyamide-amine cationic compounds, which can be used as inverse demulsifiers for oilfield sewage to break demulsification of binary flooding heavy oil produced fluids with high surfactant content. volume is still large.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a demulsifier that avoids the problem of viscous sediment caused by conventional cationic flocculants, while reducing the added amount, and its preparation method and application in the demulsification of produced fluid from binary composite flooding.

In order to achieve the above object, one aspect of the present invention provides a preparation method of a demulsifier, the method comprising:

(1) in the presence of an etherification catalyst, a block polyether is obtained by reacting an initiator, ethylene oxide and propylene oxide; wherein, the block polyether comprises a polyether segment combined with the initiator, The polyether segment is a block copolymer formed by the reaction of ethylene oxide and propylene oxide; the initiator is an organic compound with one or more groups in hydroxyl, carboxyl and amine groups;

(2) in the presence of an esterification catalyst and a polymerization inhibitor, the block polyether is subjected to a transesterification reaction with an unsaturated carboxylate, so that the end of the block polyether has an unsaturated carboxylate, and then the pressure is reduced The alcohol is distilled off to obtain an esterified product;

(3) in the presence of a free radical initiator and a polymerization assistant, the esterification product is subjected to a polymerization reaction with a cationic unsaturated monomer, so that the unsaturated carboxylate end of the block polyether is connected by a cationic unsaturated mono The polymerized segment formed by the body, thereby obtaining the demulsifier;

The weight ratio of the esterification product and the amount of the cationic unsaturated monomer is 1:1-10.

A second aspect of the present invention provides a demulsifier prepared by the above method.

The third aspect of the present invention provides the application of the above-mentioned demulsifier in the demulsification of produced fluid of binary compound flooding.

The demulsifier provided by the invention can obtain superior demulsification effect on the produced fluid of binary composite flooding at a lower dosage, and can avoid the problem of sticky sediment caused by conventional cationic flocculants and avoid the pollution of oil products.

Detailed ways

The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

One aspect of the present invention provides a preparation method of a demulsifier, the method comprising:

(1) in the presence of an etherification catalyst, a block polyether is obtained by reacting an initiator, ethylene oxide and propylene oxide; wherein, the block polyether comprises a polyether segment combined with the initiator, The polyether segment is a block copolymer formed by the reaction of ethylene oxide and propylene oxide; the initiator is an organic compound with one or more groups in hydroxyl, carboxyl and amine groups;

(2) in the presence of an esterification catalyst and a polymerization inhibitor, the block polyether is subjected to a transesterification reaction with an unsaturated carboxylate, so that the end of the block polyether has an unsaturated carboxylate, and then the pressure is reduced The alcohol is distilled off to obtain an esterified product;

(3) in the presence of a free radical initiator and a polymerization assistant, the esterification product is subjected to a polymerization reaction with a cationic unsaturated monomer, so that the unsaturated carboxylate end of the block polyether is connected by a cationic unsaturated mono The polymerized segment formed by the body, thereby obtaining the demulsifier;

The weight ratio of the esterification product and the amount of the cationic unsaturated monomer is 1:1-10.

According to the present invention, in step (1), the initiator is polymerized with ethylene oxide or propylene oxide so that the polymerized block of ethylene oxide or propylene oxide is connected to the initiator, and then the ring is added step by step. Ethylene oxide or propylene oxide, continue to form a new block based on the previous block. Such blocks may be diblock or multiblock. Of course, multiple such block structures may be bonded per molecule of initiator.

In a preferred embodiment of the present invention, the initiator is first connected to the polymerized block of propylene oxide, and the polymerized block of propylene oxide is connected to the polymerized block of ethylene oxide, and the ring The polymerized block of ethylene oxide is then connected with the new polymerized block of propylene oxide to form the initiator - the polymerized block of propylene oxide - the polymerized block of ethylene oxide - the polymerized block of propylene oxide. Triblock structure.

In another preferred embodiment of the present invention, the initiator is first connected with the polymerized block of propylene oxide, and the polymerized block of propylene oxide is connected with the polymerized block of ethylene oxide to form Diblock structure of initiator - polymeric block of propylene oxide - polymeric block of ethylene oxide.

According to the present invention, preferably, the weight ratio of the amount of ethylene oxide and propylene oxide used is 0.1-10:1, preferably 0.25-2.5:1.

According to the present invention, the initiator can be one or more of alcohols, amines, phenols, carboxylic acids, amides, phenolic resins, phenolamine resins and polyvinylpolyamines, preferably monohydric alcohols, dihydric alcohols, One or more of alkylphenolic resin, alkylphenolamine resin and polyvinylpolyamine, more preferably alkylphenolic resin and/or polyvinylpolyamine. Wherein, the alkyl phenolic resin may be, for example, one or more of nonylphenolic resin, octylphenolic resin, and the like. The polyethylene polyamine can be, for example, one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and the like.

According to the present invention, preferably, the weight ratio of the initiator to the total amount of ethylene oxide and propylene oxide is 1:10-700.

According to the present invention, the etherification catalyst refers to a catalyst that can catalyze the polymerization of ethylene oxide and/or propylene oxide to obtain a polyether polymer, and such a catalyst can be a basic catalyst, such as sodium hydroxide, hydrogen One or more of potassium oxide, metal sodium, metal lithium and metal potassium; it can also be a Lewis acid, such as BF ₃ , AlCl ₃ , etc.; it can also be a catalyst for coordination cation polymerization, such as a catalyst with a metal-oxygen bond compounds and alkaline earth metal compounds, etc. Preferably, the etherification catalyst is an alkali catalyst, more preferably one or more of sodium hydroxide, potassium hydroxide, metallic sodium, metallic lithium and metallic potassium. Preferably, based on the total amount of ethylene oxide and propylene oxide, the amount of the etherification catalyst is 0.1-2% by weight.

According to the present invention, the conditions for preparing the block polyether can adopt the conditions of the polymerization reaction of ethylene oxide and propylene oxide conventional in the art, for example, it can be carried out at 100-150 ° C. In order to prepare the block polymer, it can be The next monomer is added after each monomer reaction is substantially complete.

According to the present invention, in step (2), the hydroxyl group of the block polyether can be reacted with the unsaturated carboxylate by means of transesterification to generate by-product alcohol, and the unsaturated carboxylate can be reacted with the block polymer. The ends of the ether are connected by ester bonds to obtain the block polyether with unsaturated carboxylate at the end required by the present invention, and then the alcohol can be easily removed by distillation under reduced pressure to obtain the esterified product.

According to the present invention, preferably, the block polyether used in step (2) is a block polyether A obtained by using an alkyl phenolic resin as a starting agent and a block polyether A obtained by using polyvinyl polyamine as a starting agent A combination of ether B. More preferably, the weight ratio of the block polyether A and the block polyether B is 1:0.2-5, preferably 1:0.5-1.

According to the present invention, preferably, the unsaturated carboxylic acid ester is methyl or ethyl ester of unsaturated carboxylic acid, preferably methyl ester, more preferably methyl acrylate, methyl methacrylate, dimethyl maleate , one or more of monomethyl maleate, dimethyl fumarate, monomethyl fumarate, dimethyl itaconate and monomethyl itaconate.

Wherein, the ratio of the block polyether to the unsaturated carboxylate can be varied within a wide range, preferably, the weight ratio of the block polyether to the unsaturated carboxylate is 100:0.5- 100, preferably 100:0.8-50, more preferably 100:1-10.

According to the present invention, the esterification catalyst is a catalyst that can catalyze the above-mentioned transesterification reaction, preferably an acid catalyst, more preferably one or more of sulfuric acid, phosphoric acid and p-toluenesulfonic acid. Preferably, based on the total weight of the block polyether and the unsaturated carboxylic acid ester, the amount of the esterification catalyst used is 0.1-8% by weight, preferably 0.4-1.5% by weight.

According to the present invention, the polymerization inhibitor can prevent the polymerization reaction between the unsaturated carboxylic acid esters. Preferably, the polymerization inhibitor is hydroquinone and/or p-hydroxyanisole. More preferably, based on the total weight of the block polyether and the unsaturated carboxylate, the amount of the polymerization inhibitor used is 0.1-1 wt %, preferably 0.2-0.6 wt %.

According to the present invention, preferably, in step (2), the conditions of the transesterification reaction include: a temperature of 80-120° C. and a time of 1-10 h.

According to the present invention, in step (3), the added cationic unsaturated monomer will undergo a free radical polymerization reaction with the unsaturated bond of the unsaturated carboxylic acid ester connected to the esterification product, so that after the unsaturated carboxylic acid ester A polymerized segment formed from a cationically unsaturated monomer is attached to obtain the demulsifier of the present invention.

According to the present invention, the weight ratio of the amount of the esterified product to the cationic unsaturated monomer needs to be in the range of 1:1-10, preferably, the weight ratio of the amount of the esterified product to the amount of the cationic unsaturated monomer is 1:2-4.

According to the present invention, the cationic unsaturated monomer is allyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, 2-(methacrylamido)ethyltrimethylammonium chloride One or more of ammonium chloride and (3-acrylamidopropyl)trimethylammonium chloride.

According to the present invention, the free radical initiator can be any initiator capable of initiating the above-mentioned polymerization reaction of the present invention, preferably, the free radical initiator is potassium persulfate, ammonium persulfate, dicumyl peroxide and One or more of dibenzoyl peroxide.

Wherein, the amount of the free radical initiator can be varied within a wide range, preferably, based on the total weight of the esterification product and the cationic unsaturated monomer, the amount of the free radical initiator is 1- 10% by weight, preferably 6-8% by weight.

According to the present invention, preferably, the polymerization assistant is one or more of Na ₄ EDTA, Na ₂ EDTA, EDTA and DTPA.

Wherein, the amount of the polymerization assistant can be varied within a wide range, preferably, based on the total weight of the esterified product and the cationic unsaturated monomer, the amount of the polymerization assistant is 0.5-5 by weight %, preferably 0.8-1.2% by weight.

According to the present invention, the polymerization reaction is preferably carried out in the presence of water, preferably, based on the total weight of the esterified product and the cationically unsaturated monomer, the amount of water used is 30-80% by weight, preferably 40% by weight. -70% by weight.

According to the present invention, preferably, in step (3), the polymerization reaction includes: firstly reacting at 40-60° C. for 1-10 hours, and then reacting at 60-90° C. for 1-10 hours. More preferably, the polymerization reaction includes: firstly reacting at 45-55°C for 2-5h, and then reacting at 65-80°C for 2-5h.

A second aspect of the present invention provides a demulsifier prepared by the above method.

The third aspect of the present invention provides the application of the above-mentioned demulsifier in the demulsification of produced fluid of binary compound flooding.

When the above-mentioned demulsifier of the present invention is used in the demulsification of the produced fluid of the binary compound flooding, it can obtain a more superior demulsification effect with less dosage, and will not cause oil pollution.

The present invention will be described in detail below by means of examples.

Polyether Preparation Example 1

In the autoclave, add 15g nonyl phenolic resin (relative molecular mass is 1090) and 0.9g potassium hydroxide, drip 36.2g propylene oxide, control the reaction temperature 130 ℃, when the reaction pressure is no longer reduced (as the reaction is complete. ), then add 65.8g of ethylene oxide dropwise, control the temperature to 130°C and the pressure to 2.3kg/cm ² , when the ethylene oxide reaction is complete, add 72.5g of propylene oxide at this temperature, continue the reaction for 0.5h, wait for the kettle The pressure drop is 0kg/m ² , and the material is cooled and discharged to obtain block polyether A1.

Polyether Preparation Example 2

Add 5g tetraethylenepentamine, 2.4g potassium hydroxide and 400g propylene oxide to the autoclave, replace with nitrogen three times, heat up to 115°C, keep the temperature until the pressure is 0, continue to react for 0.5h, then heat up to 130°C, 200 g of ethylene oxide was added dropwise until the pressure no longer decreased to obtain block polyether A2.

Example 1

This example is used to illustrate the demulsifier of the present invention and its preparation method.

(1) 50 g of block polyether A1 and 50 g of block polyether A2, 0.9 g of p-toluenesulfonic acid and 0.34 g of hydroquinone were added to the reaction vessel, stirred and heated to 105° C., and added dropwise. 1.18 g of methyl methacrylate was added dropwise, and the reaction was kept at 105° C. for 4 hours, and methanol was distilled off under reduced pressure to obtain the esterified product B1.

(2) 6.5g of esterification product B1, 13.1g of cationic monomer methacryloyloxyethyltrimethylammonium chloride, 8.4g of deionized water, 1.5g of ammonium persulfate and 0.2g of Na ₄ EDTA were added Put it into the reaction vessel, stir and mix, pass N ₂ in the reaction system to deoxygenate for 20 minutes, first heat up to 50 °C for 3 hours, then to 70 °C for 3 hours, cool and discharge to get the polymer product, which is demulsifier C1.

Example 2

This example is used to illustrate the demulsifier of the present invention and its preparation method.

(1) 60g of block polyether A1 and 40g of block polyether A2, as well as 1.2g of sulfuric acid and 0.5g of p-hydroxyanisole were added to the reaction vessel, and the temperature was raised to 110°C with stirring, and 2g of methyl methacrylate was added dropwise. After the dropwise addition of methyl methacrylate, the reaction was kept at 110° C. for 4 hours, and methanol was distilled off under reduced pressure to obtain the esterified product B2.

(2) 6.5g of esterification product B2, 18g of cationic monomer (3-acrylamidopropyl)trimethylammonium chloride, 10g of deionized water, 1.6g of ammonium persulfate and 0.2g of Na ₄ EDTA were added to the The reaction vessel was stirred and mixed, and N ₂ was passed through the reaction system to deoxygenate for 20 minutes. The temperature was first heated to 55 °C for 2.5 hours, and then to 80 °C for 2 hours. The polymer product was cooled and discharged, which was demulsifier C2.

Example 3

This example is used to illustrate the demulsifier of the present invention and its preparation method.

According to the method described in Example 1, the difference is that in step (1), an equal weight of block polyether A1 is used instead of block polyether A2, thereby preparing demulsifier C3.

Example 4

This example is used to illustrate the demulsifier of the present invention and its preparation method.

According to the method described in Example 1, the difference is that in step (1), block polyether A2 of equal weight is used instead of block polyether A1, thereby preparing demulsifier C4.

Example 5

This example is used to illustrate the demulsifier of the present invention and its preparation method.

According to the method described in Example 1, the difference is that in step (2), the consumption of methacryloyloxyethyltrimethylammonium chloride is 6.5g, the consumption of deionized water is 5.6g, and the consumption of ammonium persulfate is 6.5g. The amount of Na 4 EDTA is 1 g, and the amount of Na ₄ EDTA is 0.13 g; thus the demulsifier C5 is prepared.

Example 6

This example is used to illustrate the demulsifier of the present invention and its preparation method.

According to the method described in Example 1, the difference is that in step (2), the consumption of methacryloyloxyethyltrimethylammonium chloride is 50g, the consumption of deionized water is 24g, and the consumption of ammonium persulfate The amount of Na 4 EDTA was 4.3 g, and the amount of Na ₄ EDTA was 0.57 g; thus, the demulsifier C6 was prepared.

Comparative Example 1

The esterified product B1 obtained in step (1) of Example 1 was used as the demulsifier DC1.

Comparative Example 2

(1) Add 4.2g of acrylic acid, 50g of block polyether A1, 0.62g of p-toluenesulfonic acid, 0.012g of hydroquinone and 60mL of toluene into the reactor, install a water separator, stir and heat up to 125-130°C , the reflux reaction is 8h, and the esterification product solution is obtained;

(2) 9.3g of acrylic acid, 3.1g of benzoyl peroxide and 50mL of toluene were added to the above esterification product solution, reacted under _N2 environment and 85°C for 8h, and the solvent was evaporated to obtain a polymer product, which was used as a demulsifier DC2.

Comparative Example 3

According to the method described in Example 1, the difference is that in step (2), the consumption of methacryloyloxyethyltrimethylammonium chloride is 2g, the consumption of deionized water is 3.6g, and the consumption of ammonium persulfate is 2g. The dosage is 0.65 g, and the dosage of Na ₄ EDTA is 0.09 g; thus the demulsifier DC3 is prepared.

Comparative Example 4

According to the method described in Example 1, the difference is that in step (2), the consumption of methacryloyloxyethyltrimethylammonium chloride is 78g, the consumption of deionized water is 36g, and the consumption of ammonium persulfate is 6.5 g, and the amount of Na ₄ EDTA is 0.9 g; thus the demulsifier DC4 is prepared.

test case

The produced fluid from Gudao Oil Production Plant of Shengli Oilfield was used as the evaluation object to investigate the demulsification effect of the demulsifier. In the test, the oil phase and water phase were separated from the stratified produced fluid. After preheating, re-mix with an emulsifying machine. Take the well-mixed extraction solution, add 50 μg/g of the above demulsifier (that is, 50 μg of demulsifier per g of emulsion), mix by hand, and place it in a turbiscan emulsion stability analyzer. The water-phase height and water-phase light transmittance were measured using the method of , and the results are shown in Table 1. Among them, the higher the water-phase height and the greater the water-phase light transmittance, the better the demulsification effect.

Table 1

It can be seen that the demulsifier of the present invention can obtain superior demulsification effect on the produced fluid of binary composite flooding at a lower dosage.

The preferred embodiments of the present invention have been described above in detail, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (10)

1. a preparation method of demulsifier, is characterized in that, the method comprises: (1) in the presence of an etherification catalyst, a block polyether is obtained by reacting an initiator, ethylene oxide and propylene oxide; wherein, the block polyether comprises a polyether segment combined with the initiator, The polyether segment is a block copolymer formed by the reaction of ethylene oxide and propylene oxide; the initiator is an organic compound with one or more groups in hydroxyl, carboxyl and amine groups; (2) in the presence of an esterification catalyst and a polymerization inhibitor, the block polyether is subjected to a transesterification reaction with an unsaturated carboxylate, so that the end of the block polyether has an unsaturated carboxylate, and then the pressure is reduced The alcohol is distilled off to obtain an esterified product; (3) in the presence of a free radical initiator and a polymerization assistant, the esterification product is subjected to a polymerization reaction with a cationic unsaturated monomer, so that the unsaturated carboxylate end of the block polyether is connected by a cationic unsaturated mono The polymerized segment formed by the body, thereby obtaining the demulsifier; The weight ratio of the esterification product and the amount of the cationic unsaturated monomer is 1:1-10. 2. The method according to claim 1, wherein the initiator is one or more of monohydric alcohol, dihydric alcohol, alkylphenolic resin, alkylphenolamine resin and polyvinylpolyamine, preferably Alkylphenolic resin and/or polyvinylpolyamine; Preferably, the weight ratio of the initiator to the total amount of ethylene oxide and propylene oxide is 1:10-700; Preferably, the amount of ethylene oxide and propylene oxide is used in a weight ratio of 0.1-10:1, preferably 0.25-2.5:1. 3. The method according to claim 1 or 2, wherein the etherification catalyst is an alkaline catalyst, preferably one or more of sodium hydroxide, potassium hydroxide, metallic sodium, metallic lithium and metallic potassium ; Preferably, based on the total amount of ethylene oxide and propylene oxide, the amount of the etherification catalyst is 0.1-2% by weight. 4. method according to claim 1 and 2, wherein, the block polyether that adopts in step (2) is the block polyether A that obtains with alkyl phenolic resin as initiator and with polyvinyl polyamine as The combination of block polyether B obtained by the initiator; Preferably, the weight ratio of the block polyether A and the block polyether B is 1:0.2-5, preferably 1:0.5-1. 5. The method according to any one of claims 1-4, wherein the unsaturated carboxylic acid ester is methyl acrylate, methyl methacrylate, dimethyl maleate, monomethyl maleate , one or more of dimethyl fumarate, monomethyl fumarate, dimethyl itaconate and monomethyl itaconate; Preferably, the weight ratio of the amount of the block polyether to the unsaturated carboxylate is 100:0.5-100, preferably 100:0.8-50, more preferably 100:1-10. 6. The method according to any one of claims 1-5, wherein the esterification catalyst is one or more of sulfuric acid, phosphoric acid and p-toluenesulfonic acid; Preferably, based on the total weight of the block polyether and the unsaturated carboxylate, the amount of the esterification catalyst used is 0.1-8% by weight, preferably 0.4-1.5% by weight; Preferably, the polymerization inhibitor is hydroquinone and/or p-hydroxyanisole; Preferably, based on the total weight of the block polyether and the unsaturated carboxylate, the amount of the polymerization inhibitor used is 0.1-1% by weight, preferably 0.2-0.6% by weight; Preferably, in step (2), the conditions for the transesterification reaction include: a temperature of 80-120° C. and a time of 1-10 h. 7. The method according to any one of claims 1-6, wherein the weight ratio of the esterification product and the consumption of the cationic unsaturated monomer is 1:2-4; Preferably, the cationic unsaturated monomer is allyl trimethyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, 2-(methacrylamido) ethyl trimethyl chloride One or more of ammonium chloride and (3-acrylamidopropyl)trimethylammonium chloride. 8. The method according to any one of claims 1-7, wherein the free radical initiator is one of potassium persulfate, ammonium persulfate, dicumyl peroxide and dibenzoyl peroxide one or more; Preferably, based on the total weight of the esterified product and the cationic unsaturated monomer, the amount of the free radical initiator used is 1-10% by weight, preferably 6-8% by weight; Preferably, the polymerization assistant is one or more of Na ₄ EDTA, Na ₂ EDTA, EDTA and DTPA; Preferably, based on the total weight of the esterified product and the cationic unsaturated monomer, the amount of the polymerization assistant is 0.5-5% by weight, preferably 0.8-1.2% by weight; Preferably, in step (3), the polymerization reaction includes: firstly reacting at 40-60° C. for 1-10 hours, and then reacting at 60-90° C. for 1-10 hours; more preferably, the polymerization reaction includes: firstly reacting at 40-60° C. for 1-10 hours React at 45-55°C for 2-5h, then at 65-80°C for 2-5h. 9. A demulsifier prepared by the method of any one of claims 1-8. 10. The application of the demulsifier of claim 9 in the demulsification of produced fluid from binary composite flooding.