Composite high-flash-point demulsifier and preparation method thereof

Abstract

The present application relates to the oil field chemical technology field, it is a kind of composite high flash point demulsifier and its preparation method, preparation method includes preparation polyether A: preparation polyether B: polyether A and polyether B are mixed, propylene carbonate, methanol and water are sequentially added, after being mixed uniformly, composite high flash point demulsifier is obtained.The composite high flash point demulsifier of the present application has the characteristics of safety and environmental protection, product flash point is more than 60 DEG C, storage and transport and on-site use safety.Drug dosage is low, dilute oil normal temperature 25 DEG C can be high-efficiency demulsification, thick oil dehydration temperature is also significantly optimized, energy consumption is lower.It is excellent in applicability to dilute oil and thick oil, dilute oil dehydration rate is close to 100%, thick oil dehydration rate can reach more than 97.5%, oil-water interface is neat, the ability of removing crude oil suspended matter is outstanding, the comprehensive use cost is low, multiple advantages of safety, environmental protection and high-efficiency dehydration are considered.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically a composite high flash point demulsifier and its preparation method. Background Technology

[0002] As major oilfields across China enter their mid-to-late stages of development, the water content of crude oil is increasing year by year. Domestic oilfields are entering a high-water-cut phase, with some regions seeing average water content in heavy oil exceeding 90% and light oil approaching 80%. The application of various enhanced oil recovery technologies, such as steam flooding, polymer flooding, multi-component composite flooding, and fracturing, has increased the stability of crude oil emulsions, making demulsification and dehydration more difficult. Simultaneously, a negative list requirement for additives has been introduced to prevent toxic and harmful chemicals from entering the crude oil extraction system, making the use of environmentally friendly materials to assist in crude oil extraction a necessity for the industry.

[0003] To address the challenge of crude oil dehydration, oilfields currently employ methods such as increasing crude oil processing temperature and demulsifier dosage, which inevitably leads to energy waste and higher processing costs. Simultaneously, in an effort to save costs, raw materials often contain toxic and harmful substances. However, in accordance with the requirements of CNPC (China National Petroleum Corporation), the use of highly hazardous raw materials listed in the negative list is strictly prohibited to ensure the environmental friendliness and economic efficiency of oilfield additives. Reducing dehydration temperature and demulsifier dosage while ensuring that crude oil water content meets standards has become a pressing issue for oilfields. Therefore, research into environmentally friendly, high-flash-point, and efficient dehydration technology is imperative.

[0004] Chemical demulsification and dehydration involves adding surfactants to crude oil to remove water. Currently, block copolymers or random copolymers of polyoxyethylene ether and polyoxypropylene ether are commonly used. However, polyether-based demulsifiers exhibit strong selectivity for crude oil and require high demulsification temperatures, which cannot fully meet the demands of industrial applications. my country has developed an environmentally friendly, high-flash-point composite demulsifier synthesized by ring-opening polymerization of polyols under alkali catalysis. This demulsifier is prepared using a "bone-addition, cross-linking, and compounding" process. Modifying the "bone-addition, cross-linking, and compounding" process and designing and synthesizing highly active initiators with good demulsification properties plays a crucial role in the demulsifier's synthesis. The synthesized demulsifier must meet the requirements of safety and environmental friendliness, high flash point, good dehydration effect, broad application range, and minimal risk of combustion or explosion.

[0005] However, existing demulsifier technologies have significant shortcomings, making it difficult to simultaneously meet the requirements of environmental protection, safety, and efficient dehydration. Chinese patent document CN112745890A discloses an oil-soluble demulsifier for oilfield use and its preparation method. The solvent is polyoxymethylene dimethyl ether with a degree of polymerization of 3 and / or polyoxymethylene dimethyl ether with a degree of polymerization of 4; the drying agent is polyoxyethylene polyoxypropylene octadecyl alcohol ether and / or polyoxyethylene polyoxypropylene polyether. This scheme uses polyether as the main agent and polyoxymethylene dimethyl ether and methanol as a mixed solvent. Although suitable for heavy oils with high water content, the flash point of the mixed solvent is only 28°C to 32°C, still classifying it as flammable and failing to meet the safety requirements of "non-hazardous chemicals." Furthermore, the methanol it contains is a precursor to toxic substances, polyoxymethylene dimethyl ether has poor biodegradability, insufficient environmental compliance, and the solvent rapidly evaporates at high temperatures (>80°C), causing a sharp drop in the flash point and a significant increase in safety risks.

[0006] Chinese patent document CN102492460A discloses a method for preparing a low-temperature demulsifier for crude oil and its application. This method uses a compound of polyethylene polyamine polyether and alkylphenol polyether to achieve low-temperature demulsification at 34°C to 38°C. However, it is only effective for light oil with low water content (<40%). For heavy oil with high water content (>70%), the dehydration rate is less than 60% when the temperature is below 60°C. More importantly, the alkylphenol polyether (APEO) it contains is difficult to degrade and has high ecotoxicity. At the same time, it settles slowly at low temperatures, requiring 4 to 6 hours to reach the standard, resulting in low processing efficiency and failing to meet the current oilfield's demand for efficient and environmentally friendly extraction.

[0007] In summary, there is still an urgent need for a composite demulsifier that is safe and environmentally friendly, has a high flash point, high low-temperature dehydration efficiency, low dosage, is applicable to both light and heavy oils, and fully complies with the negative list requirements of CNPC's oilfield chemical components, in order to meet the actual production needs of oilfields for efficient, low-consumption, green, and safe demulsification and dehydration during the high water-cut period. Summary of the Invention

[0008] This invention provides a composite high flash point demulsifier and its preparation method, which overcomes the shortcomings of the prior art. It can effectively solve the problems of existing demulsifiers, such as low flash point, lack of environmental protection, high dehydration temperature, large dosage, and poor adaptability to high water content crude oil.

[0009] One of the technical solutions of this invention is achieved through the following measures: a method for preparing a composite high flash point demulsifier, comprising the following steps: Step S1, Preparation of polyether A: S101, under the protection of an inert gas, the required amount of polyethylene polyamine, propylene oxide and formaldehyde are added to the reactor and stirred thoroughly. The mixture is then heated to react and polyether A initiator is obtained. S102, add propylene oxide, ethylene oxide and potassium hydroxide to polyether A initiator, carry out polymerization reaction, terminate the reaction after the reaction is completed, and obtain polyether A (XK-1). Step S2, Preparation of polyether B: S201, under the protection of an inert gas, the required amounts of glycerol, propylene oxide and potassium hydroxide are added to the reactor in sequence and stirred thoroughly. The mixture is then heated to react and polyether B initiator is obtained. S202, add propylene oxide, ethylene oxide and potassium hydroxide to the polyether B initiator, mix thoroughly and carry out the polymerization reaction. After the reaction is completed, terminate the reaction to obtain polyether B (XK-2). Step S3, Preparation of demulsifier: Polyether A and polyether B are mixed, and propylene carbonate, methanol and water are added in sequence. After mixing evenly, a composite high flash point demulsifier is obtained.

[0010] The following are further optimizations and / or improvements to the above-mentioned technical solution: In step S101 above, the polyethylene polyamine is tetraethylenepentamine.

[0011] In step S101 above, the mass ratio of polyethylene polyamine, propylene oxide and potassium hydroxide is 1:(8 to 12):(0.03 to 0.05).

[0012] In step S102 above, the mass ratio of polyether A initiator, propylene oxide, ethylene oxide and potassium hydroxide is (40 to 48): (450 to 490): (190 to 210): (1).

[0013] In step S101 above, the reaction temperature is 135℃ to 145℃, and the reaction time is 90min to 120min.

[0014] In step S102 above, the polymerization temperature is 135°C to 145°C, and the reaction time is 210 min to 240 min.

[0015] In step S201 above, the mass ratio of glycerol, propylene oxide and potassium hydroxide is (25 to 30): (240 to 260): (1).

[0016] In step S202 above, the mass ratio of polyether B initiator, propylene oxide, ethylene oxide and potassium hydroxide is (28 to 35): (270 to 300): (150 to 160): (1).

[0017] In step S201 above, the reaction temperature is 135℃ to 145℃, and the reaction time is 90min to 120min.

[0018] In step S202 above, the polymerization temperature is 135°C to 145°C, and the reaction time is 150 min to 180 min.

[0019] In step S3 above, the mass ratio of polyether A to polyether B is (6 to 8): (2 to 4).

[0020] In step S3 above, the amount of propylene carbonate added is 15% to 20% of the total mass of polyether A and polyether B, the amount of methanol added is 3% to 5% of the total mass of polyether A and polyether B, and the amount of water added is 30% to 50% of the total mass of polyether A and polyether B.

[0021] In step S3 above, the mixing temperature is 50°C to 65°C.

[0022] The second technical solution of the present invention is achieved by the following measures: a composite high flash point demulsifier prepared by a method of preparing a composite high flash point demulsifier according to one of the technical solutions.

[0023] This invention provides a composite high flash point demulsifier, synthesized by ring-opening addition of polyethylene polyamine, formaldehyde, and propylene oxide. It is safe and environmentally friendly, contains no prohibited raw materials, and has a flash point exceeding 60°C, ensuring safety during storage, transportation, and on-site use. The dosage is low, achieving efficient demulsification of light oils at room temperature (25°C) and significantly optimizing the dehydration temperature of heavy oils, resulting in lower energy consumption. It exhibits excellent applicability to both light and heavy oils, achieving near 100% dehydration for light oils and over 97.5% for heavy oils. It maintains a regular oil-water interface, demonstrates outstanding ability to remove suspended solids from crude oil, and boasts low overall operating costs, combining safety, environmental friendliness, and highly efficient dehydration. Detailed Implementation

[0024] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.

[0025] The present invention will be further described below with reference to embodiments: Example 1: The preparation method of this composite high flash point demulsifier includes the following steps: Step S1, Preparation of polyether A: S101, under the protection of an inert gas, the required amount of polyethylene polyamine, propylene oxide and formaldehyde are added to the reactor and stirred thoroughly. The mixture is then heated to react and polyether A initiator is obtained. S102, add propylene oxide, ethylene oxide and potassium hydroxide to polyether A initiator, carry out polymerization reaction, terminate the reaction after the reaction is completed, and obtain polyether A (XK-1). Step S2, Preparation of polyether B: S201, under the protection of an inert gas, the required amounts of glycerol, propylene oxide and potassium hydroxide are added to the reactor in sequence and stirred thoroughly. The mixture is then heated to react and polyether B initiator is obtained. S202, add propylene oxide, ethylene oxide and potassium hydroxide to the polyether B initiator, mix thoroughly and carry out the polymerization reaction. After the reaction is completed, terminate the reaction to obtain polyether B (XK-2). Step S3, Preparation of demulsifier: Polyether A and polyether B are mixed, and propylene carbonate, methanol and water are added in sequence. After mixing evenly, a composite high flash point demulsifier is obtained.

[0026] Example 2: As an optimization of the above example, in step S101, the polyethylene polyamine is tetraethylenepentamine.

[0027] Example 3: As an optimization of the above example, in step S101, the mass ratio of polyethylene polyamine, propylene oxide and potassium hydroxide is 1:(8 to 12):(0.03 to 0.05).

[0028] Example 4: As an optimization of the above example, in step S102, the mass ratio of polyether A initiator, propylene oxide, ethylene oxide and potassium hydroxide is (40 to 48): (450 to 490): (190 to 210): (1).

[0029] Example 5: As an optimization of the above example, in step S101, the reaction temperature is 135°C to 145°C and the reaction time is 90 min to 120 min.

[0030] Example 6: As an optimization of the above example, in step S102, the polymerization temperature is 135°C to 145°C and the reaction time is 210 min to 240 min.

[0031] Example 7: As an optimization of the above example, in step S201, the mass ratio of glycerol, propylene oxide and potassium hydroxide is (25 to 30): (240 to 260): (1).

[0032] Example 8: As an optimization of the above example, in step S201, the mass ratio of polyether B initiator, propylene oxide, ethylene oxide and potassium hydroxide is (28 to 35): (270 to 300): (150 to 160): (1).

[0033] Example 9: As an optimization of the above example, in step S201, the reaction temperature is 135°C to 145°C and the reaction time is 90 min to 120 min.

[0034] Example 10: As an optimization of the above example, in step S202, the polymerization temperature is 135°C to 145°C and the reaction time is 150 min to 180 min.

[0035] Example 11: As an optimization of the above example, in step S3, the mass ratio of polyether A to polyether B is (6 to 8): (2 to 4).

[0036] Example 12: As an optimization of the above example, in step S3, the amount of propylene carbonate added is 15% to 20% of the total mass of polyether A and polyether B, the amount of methanol added is 3% to 5% of the total mass of polyether A and polyether B, and the amount of water added is 30% to 50% of the total mass of polyether A and polyether B.

[0037] Example 13: As an optimization of the above example, in step S3, the mixing temperature is 50°C to 65°C.

[0038] Example 14: The preparation process of this composite high flash point demulsifier is as follows: Step S1, Preparation of polyether A: S101. Clean the reactor thoroughly and isolate it from air. Purge with nitrogen for 10 minutes. Add 1 part of polyethylene polyamine, 10 parts of propylene oxide (PO), and 0.035 parts of formaldehyde to the reactor in sequence. Stir thoroughly and mix well. Heat to 140℃ and react for 90 minutes to obtain polyether A initiator (polyamine-10). S102, the reactor containing polyether A initiator was isolated from air again, and 478 parts of propylene oxide, 200 parts of ethylene oxide and 1 part of potassium hydroxide were added and mixed thoroughly. The temperature was controlled at 140℃ and the polymerization reaction was carried out for 210 minutes. After the reaction was completed, a small amount of glacial acetic acid was added to neutralize the catalyst potassium hydroxide and terminate the reaction, and polyether A (XK-1) was obtained.

[0039] Step S2, Preparation of polyether B: S201. Clean the synthesis reactor thoroughly and isolate it from air. Purge with nitrogen for 10 minutes. Add 28 parts of glycerol, 250 parts of propylene oxide and 1 part of potassium hydroxide to the reactor in sequence. Stir well and mix thoroughly. Heat to 140℃ and react for 90 minutes to obtain polyether B initiator. S202, the reactor containing polyether B initiator is isolated from air again, and 285 parts of propylene oxide, 158 parts of ethylene oxide and 1 part of potassium hydroxide are added and mixed thoroughly. The temperature is controlled at 140℃ and the polymerization reaction is carried out for 150 minutes. After the reaction is completed, a small amount of glacial acetic acid is added to neutralize the catalyst potassium hydroxide and terminate the reaction, and polyether B (XK-2) is obtained.

[0040] Step S3, Preparation of demulsifier: Polyether A and polyether B were added to a compounding vessel in a weight ratio of 7:3, followed by the addition of 17% propylene carbonate and 3% methanol. The mixture was heated to 60°C and stirred for 30 minutes. Heating was then stopped, and 50% soft water was added. After stirring for half an hour, a composite high flash point demulsifier was obtained, denoted as demulsifier S1.

[0041] Example 15: The preparation process of this composite high flash point demulsifier is as follows: Step S1, Preparation of polyether A: S101. Clean the reactor thoroughly and isolate it from air. Purge with nitrogen for 10 minutes. Add 1 part of polyethylene polyamine, 10 parts of propylene oxide (PO), and 0.035 parts of formaldehyde to the reactor in sequence. Stir thoroughly and mix well. Heat to 140℃ and react for 90 minutes to obtain polyether A initiator (polyamine-10). S102, the reactor containing polyether A initiator is isolated from air again, and 485 parts of propylene oxide, 200 parts of ethylene oxide and 1 part of potassium hydroxide are added and mixed thoroughly. The temperature is controlled at 140℃ and the polymerization reaction is carried out for 210 minutes. After the reaction is completed, a small amount of glacial acetic acid is added to neutralize the catalyst potassium hydroxide and terminate the reaction, and polyether A (XK-1) is obtained.

[0042] Step S2, Preparation of polyether B: S201. Clean the synthesis reactor thoroughly and isolate it from air. Purge with nitrogen for 10 minutes. Add 28 parts of glycerol, 240 parts of propylene oxide and 1 part of potassium hydroxide to the reactor in sequence. Stir well and mix thoroughly. Heat to 145℃ and react for 90 minutes to obtain polyether B initiator. S202, the reactor containing polyether B initiator is isolated from air again, and 280 parts of propylene oxide, 150 parts of ethylene oxide and 1 part of potassium hydroxide are added and mixed thoroughly. The temperature is controlled at 140℃ and the polymerization reaction is carried out for 150 minutes. After the reaction is completed, a small amount of glacial acetic acid is added to neutralize the catalyst potassium hydroxide and terminate the reaction, and polyether B (XK-2) is obtained.

[0043] Step S3, Preparation of demulsifier: Polyether A and polyether B were added to a compounding vessel in a weight ratio of 8:2, followed by the addition of 17% propylene carbonate and 3% methanol. The mixture was heated to 60°C and stirred for 30 minutes. Heating was then stopped, and 50% soft water was added. After stirring for half an hour, a composite high flash point demulsifier was obtained, denoted as demulsifier S2.

[0044] Example 16: The preparation process of this composite high flash point demulsifier is as follows: Step S1, Preparation of polyether A: S101. Clean the reactor thoroughly and isolate it from air. Purge with nitrogen for 10 minutes. Add 1 part of polyethylene polyamine, 10 parts of propylene oxide (PO), and 0.035 parts of formaldehyde to the reactor in sequence. Stir thoroughly and mix well. Heat to 135℃ and react for 90 minutes to obtain polyether A initiator (polyamine-10). S102, the reactor containing polyether A initiator is isolated from air again, and 470 parts of propylene oxide, 200 parts of ethylene oxide and 1 part of potassium hydroxide are added and mixed thoroughly. The temperature is controlled at 135℃ and the polymerization reaction is carried out for 210 minutes. After the reaction is completed, a small amount of glacial acetic acid is added to neutralize the catalyst potassium hydroxide and terminate the reaction, and polyether A (XK-1) is obtained.

[0045] Step S2, Preparation of polyether B: S201. Clean the synthesis reactor thoroughly and isolate it from air. Purge with nitrogen for 10 minutes. Add 25 parts of glycerol, 250 parts of propylene oxide and 1 part of potassium hydroxide to the reactor in sequence. Stir well and mix thoroughly. Heat to 145℃ and react for 90 minutes to obtain polyether B initiator. S202, the reactor containing polyether B initiator is isolated from air again, and 300 parts of propylene oxide, 158 parts of ethylene oxide and 1 part of potassium hydroxide are added and mixed thoroughly. The temperature is controlled at 145℃ and the polymerization reaction is carried out for 150 minutes. After the reaction is completed, a small amount of glacial acetic acid is added to neutralize the catalyst potassium hydroxide and terminate the reaction, and polyether B (XK-2) is obtained.

[0046] Step S3, Preparation of demulsifier: Polyether A and polyether B were added to a compounding vessel in a weight ratio of 8:4, followed by the addition of 17% propylene carbonate and 3% methanol. The mixture was heated to 60°C and stirred for 30 minutes. Heating was then stopped, and 50% soft water was added. After stirring for half an hour, a composite high flash point demulsifier was obtained, which was designated as demulsifier S3.

[0047] Comparative Example: The difference from Example 14 is that no propylene carbonate was added, and the resulting demulsifier is designated as D1.

[0048] Test example: Crude oil No. 1 and crude oil No. 2 were selected to test S1 to S3 and D1 obtained from the above examples and comparative examples.

[0049] Crude oil No. 1 is a thin oil sample (a thin oil sample from the No. 2 Oil Production Plant of the oilfield using a composite high flash point demulsifier; the water content of crude oil No. 1 is 35.5%). Crude oil No. 2 is a heavy oil sample (a heavy oil sample from the X City Oilfield using a composite high flash point demulsifier). (Due to the use of high temperature and high pressure steam extraction during the development of the X City extra-heavy crude oil, the crude oil contains a large amount of suspended solids and impurities). The water content of crude oil No. 2 is 77%.

[0050] Demulsifiers S1 to S3 and D1 to D3 were added to crude oil No. 1 and crude oil No. 2, respectively, so that the concentrations of demulsifiers in crude oil No. 1 and crude oil No. 2 were 90 mg / L and 110 mg / L, respectively. Dehydration tests were conducted on crude oil No. 1 and crude oil No. 2 with added demulsifiers. At the same time, on-site demulsifiers were used as a control. The dehydration test of crude oil was carried out in accordance with the method specified in SY / T 5280-2018 "General Technical Conditions for Crude Oil Demulsifiers". The dehydration temperature was controlled at 25℃ and 90℃ during the test. The shaking method of the dehydration test bottle was artificial shaking.

[0051] The dehydration rate of crude oil No. 1 after adding the above demulsifier is shown in Table 1, and the dehydration rate of crude oil No. 2 after adding the above demulsifier is shown in Table 2. As can be seen from Tables 1 and 2, the composite high flash point demulsifier of the present invention achieves a demulsification and dehydration rate of 100% for crude oil No. 1, and a demulsification and dehydration rate of 97.5% for crude oil No. 2. This indicates that the composite high flash point demulsifier of the present invention has superior demulsification and dehydration performance, and the optimal mass ratio of polyether A and polyether B is 7:3.

[0052] In summary, the composite high flash point demulsifier of this invention has excellent demulsification performance, with a flash point of over 60°C. Its crude oil dehydration performance exceeds the requirements of the national standard (SY / T 5280-2018 "General Technical Conditions for Crude Oil Demulsifiers"). Crude oil treated with this invention has a clear oil-water interface, low demulsifier dosage, strong ability to remove suspended solids, and good demulsification and dehydration effect. It is economical, safe, and environmentally friendly.

[0053] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A method for preparing a composite high flash point demulsifier, characterized in that... Includes the following steps: Step S1, Preparation of polyether A: S101, under the protection of an inert gas, the required amount of polyethylene polyamine, propylene oxide and formaldehyde are added to the reactor and stirred thoroughly. The mixture is then heated to react and polyether A initiator is obtained. S102, add propylene oxide, ethylene oxide and potassium hydroxide to polyether A initiator, carry out polymerization reaction, terminate the reaction after the reaction is completed, and obtain polyether A; Step S2, Preparation of polyether B: S201, under the protection of an inert gas, the required amounts of glycerol, propylene oxide and potassium hydroxide are added to the reactor in sequence and stirred thoroughly. The mixture is then heated to react and polyether B initiator is obtained. S202, add propylene oxide, ethylene oxide and potassium hydroxide to the polyether B initiator, mix thoroughly and carry out the polymerization reaction. After the reaction is completed, terminate the reaction to obtain polyether B. Step S3, Preparation of demulsifier: Polyether A and polyether B are mixed, and propylene carbonate, methanol and water are added in sequence. After mixing evenly, a composite high flash point demulsifier is obtained.

2. The preparation method of the composite high flash point demulsifier according to claim 1, characterized in that... In step S101, the polyethylene polyamine is tetraethylenepentamine.

3. The preparation method of the composite high flash point demulsifier according to claim 1 or 2, characterized in that... In step S101, the mass ratio of polyethylene polyamine, propylene oxide, and potassium hydroxide is 1:8 to 12:0.03 to 0.05; Or / and, in step S102, the mass ratio of polyether A initiator, propylene oxide, ethylene oxide and potassium hydroxide is 40 to 48: 450 to 490: 190 to 210:

1.

4. The method for preparing the composite high flash point demulsifier according to any one of claims 1 to 3, characterized in that... In step S101, the reaction temperature is 135°C to 145°C, and the reaction time is 90 min to 120 min.

5. The method for preparing the composite high flash point demulsifier according to any one of claims 1 to 4, characterized in that... In step S102, the polymerization temperature is 135°C to 145°C, and the reaction time is 210 min to 240 min.

6. The method for preparing the composite high flash point demulsifier according to any one of claims 1 to 5, characterized in that... In step S201, the mass ratio of glycerol, propylene oxide and potassium hydroxide is 25 to 30: 240 to 260:

1. Or / and, in step S202, the mass ratio of polyether B initiator, propylene oxide, ethylene oxide and potassium hydroxide is 28 to 35: 270 to 300: 150 to 160:

1.

7. The method for preparing the composite high flash point demulsifier according to any one of claims 1 to 6, characterized in that... In step S201, the reaction temperature is 135℃ to 145℃, and the reaction time is 90 min to 120 min. Or / and, in step S202, the polymerization temperature is 135°C to 145°C, and the reaction time is 150 min to 180 min.

8. The method for preparing the composite high flash point demulsifier according to any one of claims 1 to 7, characterized in that... In step S3, the mass ratio of polyether A to polyether B is 6 to 8: 2 to 4.

9. The method for preparing the composite high flash point demulsifier according to any one of claims 1 to 8, characterized in that: In step S3, the amount of propylene carbonate added is 15% to 20% of the total mass of polyether A and polyether B, the amount of methanol added is 3% to 5% of the total mass of polyether A and polyether B, and the amount of water added is 30% to 50% of the total mass of polyether A and polyether B. Or / and, in step S3, the mixing temperature is 50°C to 65°C.

10. A composite high flash point demulsifier prepared by the method according to any one of claims 1 to 9.

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