A compound demulsifier for oil fields and preparation method thereof

Abstract

The present invention relates to the technical field of demulsifiers, specifically a compound demulsifier for oil fields and a preparation method thereof. The compound demulsifier for oil fields comprises the following components: 8 to 10 parts by weight of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine, 6 to 8 parts of propylene glycol polyoxypropylene polyoxyethylene ether, 5 to 7 parts of a branched demulsifier, 0.05 to 0.1 parts of silica gel powder, 17 to 23 parts of a small molecule additive, and 102 to 114 parts of an ethanol aqueous solution. The small molecule additive comprises the following components: 3 to 5 parts of sodium dodecylbenzenesulfonate, 8 to 10 parts of p-aminobenzenesulfonamide, and 6 to 8 parts of octanol; the ethanol aqueous solution has a concentration of 40 to 50 wt%.

Description

Technical Field

[0001] The invention relates to the technical field of demulsifiers, in particular to a compound demulsifier for oil fields and a preparation method thereof. Background Art

[0002] Oilfield demulsifiers are chemical reagents used to separate oil and water phases based on the principle of phase transfer and inverse deformation. Currently, commonly used demulsifiers include polyether demulsifiers, polyamide demulsifiers, polyacrylic acid demulsifiers, and compound demulsifiers. Compared to single demulsifiers, compound demulsifiers can achieve superior performance by leveraging the synergistic effects between the various components within the compound, thereby improving demulsification efficiency. They possess a variety of properties, including wettability, flocculation, and agglomeration, making them suitable for use with a variety of crude oil produced fluids from multiple oilfields, offering a broader spectrum of adaptability.

[0003] In the existing technology, although compound demulsifiers can improve the demulsification efficiency, the demulsification efficiency still needs to be improved; and their demulsification effect in different crude oils is unstable. This is because although traditional compound demulsifiers take into account the replacement of the stable water-oil interface film, they do not take into account the mass transfer problem of interfacial water molecules, resulting in low water molecule mass transfer efficiency, which makes the dehydration rate of compound demulsifiers in crude oil unstable, the dehydration time is long, and the dehydration efficiency is low.

[0004] Therefore, solving the above problems and preparing a composite demulsifier for oil fields with stronger adaptability and more stable dehydration efficiency have important application value. Summary of the Invention

[0005] The object of the present invention is to provide a composite demulsifier for oil fields and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A compound demulsifier for oil fields comprises the following components: by weight, 8 to 10 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine, 6 to 8 parts of propylene glycol polyoxypropylene polyoxyethylene ether, 5 to 7 parts of branched demulsifier aids, 0.05 to 0.1 parts of silica gel powder, 17 to 23 parts of small molecule aids, and 102 to 114 parts of ethanol aqueous solution.

[0008] More optimally, the propylene glycol polyoxypropylene polyoxyethylene ether includes but is not limited to one or more of L31, L64, L44, L68, L45, and L64.

[0009] More optimally, the small molecule auxiliary agent includes the following components: 3 to 5 parts of sodium dodecylbenzenesulfonate, 8 to 10 parts of p-aminobenzenesulfonamide, and 6 to 8 parts of octanol, by weight; the concentration of the ethanol aqueous solution is 40 to 50 wt%.

[0010] More optimally, the preparation method of the branched demulsifier comprises the following steps:

[0011] Step 1: Adding epigallocatechin gallate and aminopolyethylene glycol carboxyl group to methanol solvent in sequence and stirring evenly, then removing the methanol solvent by rotary evaporation; adding formaldehyde solution while stirring and stirring evenly; heating to 80-85° C. and reacting for 8-10 hours; rotary evaporation and low-temperature vacuum drying to obtain carboxyl branched epigallocatechin gallate;

[0012] Step 2: Carboxyl branched gallic acid catechin gallate and 1,2-epoxydodecane are sequentially added to isopropanol solvent, the temperature is raised to 70-75° C., N,N-dimethylbenzylamine catalyst and p-hydroxyanisole polymerization inhibitor are added, the temperature is raised to 85-95° C. and the mixture is reacted for 4-5 hours, and the mixture is distilled under reduced pressure to obtain a branched demulsifier.

[0013] More optimally, the raw materials of the carboxyl-branched catechin gallate include the following substances: 4 to 5 parts of catechin gallate, 21 to 22 parts of amino polyethylene glycol carboxyl, 5 to 6 parts of formaldehyde solution, and 120 parts of methanol, by weight.

[0014] More optimally, the raw materials of the branched demulsifier include the following substances: by weight, 5 to 5.6 parts of carboxyl branched gallic acid catechin gallate, 2.2 to 2.4 parts of 1,2-epoxydodecane, 0.24 to 0.25 parts of N,N-dimethylbenzylamine catalyst, and 0.005 to 0.008 parts of p-hydroxyanisole inhibitor.

[0015] More optimally, the average molecular weight of the amino polyethylene glycol carboxyl group is less than 500 g / mol.

[0016] More optimally, the propylene glycol polyoxypropylene polyoxyethylene ether is pre-modified; the modification process comprises the following steps:

[0017] Step 1: Add propylene glycol polyoxypropylene polyoxyethylene ether to xylene solvent, heat to 50-55°C under nitrogen atmosphere, and stir for 10-30 minutes; add p-toluenesulfonic acid catalyst, and add acrylic acid dropwise; heat to 110-115°C, and react for 7-8 hours to obtain an esterification product;

[0018] Step 2: adding the esterified product to xylene solvent, adding benzoyl peroxide initiator, heating to 60-90° C. and reacting for 2-6 hours, and evaporating the solvent to obtain modified propylene glycol polyoxypropylene polyoxyethylene ether.

[0019] More optimally, in the esterification product, the molar ratio of propylene glycol polyoxypropylene polyoxyethylene ether to acrylic acid is 1:

[0020] (3~3.5); p-toluenesulfonic acid accounts for 1~1.1wt% of the mass of propylene glycol polyoxypropylene polyoxyethylene ether; benzoyl peroxide initiator accounts for 1~2wt% of the mass of the esterification product.

[0021] More optimally, a method for preparing a compound demulsifier for oil fields comprises the following steps: adding an ethanol aqueous solution to a reactor, adding sodium dodecylbenzenesulfonate, p-aminobenzenesulfonamide, and octanol in sequence while stirring, and stirring for 10 to 20 minutes; adding silica gel powder while stirring, heating to 60 to 65°C and stirring for 10 to 15 minutes; adding one or two of propylene glycol polyoxypropylene polyoxyethylene ether or modified propylene glycol polyoxypropylene polyoxyethylene ether while stirring; then adding a branched demulsifier aid and polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence, heating to 70 to 75°C and continuing to stir for 30 to 40 minutes; cooling, and adding an ethanol aqueous solution to obtain a compound demulsifier for oil fields.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The main component is polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine, which contains multiple groups and has strong surface activity, capable of breaking the interfacial tension between water and oil. However, its equilibrium time is long, and the dehydration efficiency after demulsification is low. Using it alone as a demulsifier takes a long time to achieve the ideal effect, and the demulsification effect is limited. Therefore, in this scheme, first, propylene glycol polyoxypropylene polyoxyethylene ether is used to reduce surface tension, increase the hydrophilicity of the droplets, and promote the interaction of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine at the water-oil interface layer, thereby accelerating the demulsification process. Second, by introducing a branched demulsification aid, the permeability of the demulsifier at the oil-water interface is enhanced, thereby assisting in enhancing the demulsification rate and dehydration efficiency. Third, by introducing a small molecule adjuvant, the reciprocity and interfacial spatiality of the water-oil interface layer are increased, thereby promoting demulsification and water mass transfer and improving efficiency.

[0024] The propylene glycol polyoxypropylene polyoxyethylene ether in the scheme is modified through acrylic esterification and free radical polymerization to increase its molecular weight. At the same time, oxygen-containing groups are introduced to increase the hydrogen bonding energy with interfacial water molecules, thereby assisting the polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine to more quickly and effectively damage the water-oil interfacial film. This effectively improves the mass transfer efficiency of interfacial water molecules and promotes the transfer of water molecules at the water-oil interface, thereby improving demulsification and dehydration efficiency.

[0025] The branched demulsifier introduced in the scheme is based on epigallocatechin gallate. It is grafted with amino polyethylene glycol carboxyl groups using formaldehyde, and then 1,2-epoxydodecane is grafted via the reaction of the carboxyl groups with epoxy groups to obtain the branched demulsifier. The aromatic ring structure in epigallocatechin gallate helps to generate a π-π interaction, thereby enhancing the interfacial interaction with crude oil and reducing the resistance of the molecules to the oil-water interface. The dodecane chain segment has a strong hydrophobic effect, which makes it easier to improve compatibility with crude oil. The length of the carbon chain increases its solubility in the medium, thereby compromising the extension of the hydrophilic portion of the molecule, which is more soluble in water. The ethoxy group contained in the synergistically introduced polyethylene glycol segment improves the mass transfer of water molecules at the oil-water interface, thereby improving the demulsification ability and dehydration rate. At the same time, compared with other demulsifiers, due to the difference in branched structure, this substance has stronger penetration ability at the water-oil interface, faster dehydration effect, and the separated water is clearer.

[0026] To further enhance the diffusion efficiency of the compound demulsifier in crude oil, the solution introduces small molecule additives and silica gel powder, increasing the effectiveness of the compound demulsifier and synergistically improving performance. The introduction of small molecule additives not only reduces viscosity and improves rheological properties, but also helps other components with larger molecular weights to enhance reciprocity with the oil-water interface. This also creates spatiality between demulsifier molecules in the interfacial layer, thereby assisting in improving the mass transfer of water molecules and enhancing dehydration efficiency.

[0027] In summary, through the optimization and improvement of multiple substances, the mass transfer of water molecules in the water-oil interface film layer during the demulsification process was effectively improved, the interfacial transfer was enhanced, thereby improving the demulsification efficiency and dehydration performance; ultimately, the effective separation of dense oil and water was achieved. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0029] It should be noted that the purchasers of all raw materials involved in the present invention are exemplified without any special restrictions as follows: In the following examples, parts are by mass. The CAS number of epigallocatechin gallate is 4233-96-9, the average molecular weight of aminopolyethylene glycol carboxyl group is 350 g / mol; the concentration of formaldehyde solution is 37%; the model of propylene glycol polyoxypropylene polyoxyethylene ether is L64; polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine is provided by Shijiazhuang Juye Chemical Additive Co., Ltd.; the CAS number of sodium dodecylbenzenesulfonate is 25155-30-0, the CAS number of p-aminobenzenesulfonamide is 63-74-1, the CAS number of octanol is 111-87-5, and the mesh size of silica gel powder is 600 mesh.

[0030] Example 1: Preparation method of a composite demulsifier for oil fields:

[0031] Step 1: (1) 4.5 parts of gallic acid catechin gallate and 21 parts of amino polyethylene glycol carboxyl are added to 120 parts of methanol solvent in sequence and stirred evenly, and then the methanol solvent is removed by rotary evaporation; 5.7 parts of formaldehyde solution are added under stirring and stirred evenly; the temperature is raised to 80°C for reaction for 8 hours; rotary evaporation and vacuum drying at 50°C to obtain carboxyl branched gallic acid catechin gallate; 5.5 parts of carboxyl branched gallic acid catechin gallate and 2.4 parts of 1,2-epoxydodecane are added to 100 parts of isopropanol solvent in sequence, the temperature is raised to 75°C, 0.24 parts of N,N-dimethylbenzylamine catalyst and 0.006 parts of p-hydroxyanisole inhibitor are added, the temperature is raised to 90°C for reaction for 4 hours, and vacuum distillation is performed to obtain a branched demulsifier;

[0032] (2) Add propylene glycol polyoxypropylene polyoxyethylene ether to xylene solvent, heat to 50°C and stir for 20 minutes under nitrogen atmosphere; add p-toluenesulfonic acid catalyst and dropwise add acrylic acid; heat to 110°C and react for 8 hours to obtain an esterification product; add the esterification product to xylene solvent, add benzoyl peroxide initiator, heat to 90°C and react for 4 hours, evaporate and remove the solvent to obtain modified propylene glycol polyoxypropylene polyoxyethylene ether; the molar ratio of propylene glycol polyoxypropylene polyoxyethylene ether to acrylic acid is 1:3.2; p-toluenesulfonic acid accounts for 1wt% of the mass of propylene glycol polyoxypropylene polyoxyethylene ether; benzoyl peroxide initiator accounts for 1.2wt% of the mass of the esterification product;

[0033] Step 2: Add 106 parts of 50wt% ethanol aqueous solution to the reactor, add 4 parts of sodium dodecylbenzenesulfonate, 9 parts of p-aminobenzenesulfonamide, and 7 parts of octanol in sequence while stirring, and stir for 20 minutes; add 0.1 parts of silica gel powder while stirring, heat to 60°C and stir for 15 minutes; add 8 parts of modified propylene glycol polyoxypropylene polyoxyethylene ether, 6 parts of branched demulsifier, and 10 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence while stirring, heat to 70°C and continue stirring for 30 minutes; cool, add ethanol aqueous solution to 150 parts by weight, and obtain a compound demulsifier for oil fields.

[0034] Example 2: Preparation method of a composite demulsifier for oil fields:

[0035] Step 1: (1) 4.5 parts of gallic acid catechin gallate and 21 parts of amino polyethylene glycol carboxyl are added to 120 parts of methanol solvent in sequence and stirred evenly, and then the methanol solvent is removed by rotary evaporation; 5.7 parts of formaldehyde solution are added under stirring and stirred evenly; the temperature is raised to 80°C for reaction for 8 hours; rotary evaporation and vacuum drying at 50°C to obtain carboxyl branched gallic acid catechin gallate; 5.5 parts of carboxyl branched gallic acid catechin gallate and 2.4 parts of 1,2-epoxydodecane are added to 100 parts of isopropanol solvent in sequence, the temperature is raised to 75°C, 0.24 parts of N,N-dimethylbenzylamine catalyst and 0.006 parts of p-hydroxyanisole inhibitor are added, the temperature is raised to 90°C for reaction for 4 hours, and vacuum distillation is performed to obtain a branched demulsifier;

[0036] (2) Add propylene glycol polyoxypropylene polyoxyethylene ether to xylene solvent, heat to 50°C and stir for 20 minutes under nitrogen atmosphere; add p-toluenesulfonic acid catalyst and dropwise add acrylic acid; heat to 110°C and react for 8 hours to obtain an esterification product; add the esterification product to xylene solvent, add benzoyl peroxide initiator, heat to 90°C and react for 4 hours, evaporate and remove the solvent to obtain modified propylene glycol polyoxypropylene polyoxyethylene ether; the molar ratio of propylene glycol polyoxypropylene polyoxyethylene ether to acrylic acid is 1:3.2; p-toluenesulfonic acid accounts for 1wt% of the mass of propylene glycol polyoxypropylene polyoxyethylene ether; benzoyl peroxide initiator accounts for 1.2wt% of the mass of the esterification product;

[0037] Step 2: Add 108 parts of 50wt% ethanol aqueous solution to the reactor, add 3 parts of sodium dodecylbenzenesulfonate, 10 parts of p-aminobenzenesulfonamide, and 8 parts of octanol in sequence while stirring, and stir for 20 minutes; add 0.1 parts of silica gel powder while stirring, heat to 60°C and stir for 15 minutes; add 6 parts of modified propylene glycol polyoxypropylene polyoxyethylene ether, 7 parts of branched demulsifier, and 8 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence while stirring, heat to 70°C and continue stirring for 30 minutes; cool, add ethanol aqueous solution to 150 parts by weight, and obtain a compound demulsifier for oil fields.

[0038] Example 3: Preparation method of a composite demulsifier for oil fields:

[0039] Step 1: (1) 4.5 parts of gallic acid catechin gallate and 21 parts of amino polyethylene glycol carboxyl are added to 120 parts of methanol solvent in sequence and stirred evenly, and then the methanol solvent is removed by rotary evaporation; 5.7 parts of formaldehyde solution are added under stirring and stirred evenly; the temperature is raised to 80°C for reaction for 8 hours; rotary evaporation and vacuum drying at 50°C to obtain carboxyl branched gallic acid catechin gallate; 5.5 parts of carboxyl branched gallic acid catechin gallate and 2.4 parts of 1,2-epoxydodecane are added to 100 parts of isopropanol solvent in sequence, the temperature is raised to 75°C, 0.24 parts of N,N-dimethylbenzylamine catalyst and 0.006 parts of p-hydroxyanisole inhibitor are added, the temperature is raised to 90°C for reaction for 4 hours, and vacuum distillation is performed to obtain a branched demulsifier;

[0040] (2) Add propylene glycol polyoxypropylene polyoxyethylene ether to xylene solvent, heat to 50°C and stir for 20 minutes under nitrogen atmosphere; add p-toluenesulfonic acid catalyst and dropwise add acrylic acid; heat to 110°C and react for 8 hours to obtain an esterification product; add the esterification product to xylene solvent, add benzoyl peroxide initiator, heat to 90°C and react for 4 hours, evaporate and remove the solvent to obtain modified propylene glycol polyoxypropylene polyoxyethylene ether; the molar ratio of propylene glycol polyoxypropylene polyoxyethylene ether to acrylic acid is 1:3.2; p-toluenesulfonic acid accounts for 1wt% of the mass of propylene glycol polyoxypropylene polyoxyethylene ether; benzoyl peroxide initiator accounts for 1.2wt% of the mass of the esterification product;

[0041] Step 2: Add 108 parts of 50wt% ethanol aqueous solution to the reactor, add 5 parts of sodium dodecylbenzenesulfonate, 8 parts of p-aminobenzenesulfonamide, and 6 parts of octanol in sequence while stirring, and stir for 20 minutes; add 0.1 parts of silica gel powder while stirring, heat to 60°C and stir for 15 minutes; add 8 parts of modified propylene glycol polyoxypropylene polyoxyethylene ether, 5 parts of branched demulsifier, and 10 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence while stirring, heat to 70°C and continue stirring for 30 minutes; cool, add ethanol aqueous solution to 150 parts by weight, and obtain a compound demulsifier for oil fields.

[0042] Comparative Example 1: The modified propylene glycol polyoxypropylene polyoxyethylene ether was replaced with propylene glycol polyoxypropylene polyoxyethylene ether, and the rest was the same as Example 1; the specific changes were:

[0043] Step 2: Add 106 parts of 50wt% ethanol aqueous solution to the reactor, add 4 parts of sodium dodecylbenzenesulfonate, 9 parts of p-aminobenzenesulfonamide, and 7 parts of octanol in sequence while stirring, and stir for 20 minutes; add 0.1 parts of silica gel powder while stirring, heat to 60°C and stir for 15 minutes; add 8 parts of propylene glycol polyoxypropylene polyoxyethylene ether, 6 parts of branched demulsifier, and 10 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence while stirring, heat to 70°C and continue stirring for 30 minutes; cool, add ethanol aqueous solution to 150 parts by weight, and obtain a composite demulsifier for oil fields.

[0044] Comparative Example 2: The branched demulsifier was replaced with a polyene polyamine block polyether demulsifier JMP-1 of equal mass. The rest was the same as in Example 1, with the following specific changes:

[0045] Step 2: Add 106 parts of 50wt% ethanol aqueous solution to a reactor, add 4 parts of sodium dodecylbenzenesulfonate, 9 parts of p-aminobenzenesulfonamide, and 7 parts of octanol in sequence while stirring, and stir for 20 minutes; add 0.1 parts of silica gel powder while stirring, heat to 60°C and stir for 15 minutes; add 8 parts of modified propylene glycol polyoxypropylene polyoxyethylene ether, 6 parts of polyene polyamine block polyether demulsifier JMP-1, and 10 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence while stirring, heat to 70°C and continue stirring for 30 minutes; cool, add ethanol aqueous solution to 150 parts by weight, and obtain a composite demulsifier for oil fields.

[0046] Comparative Example 3: No multiple small molecule additives were introduced, and only octanol was used. The rest was the same as in Example 1. The specific changes were as follows:

[0047] Step 2: Add 106 parts of 50wt% ethanol aqueous solution to the reactor, add 20 parts of octanol in sequence while stirring, and stir for 20 minutes; add 0.1 parts of silica gel powder while stirring, heat to 60°C and stir for 15 minutes; add 8 parts of modified propylene glycol polyoxypropylene polyoxyethylene ether, 6 parts of branched demulsifier, and 10 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence while stirring, heat to 70°C and continue stirring for 30 minutes; cool, add ethanol aqueous solution to 150 parts by weight, and obtain a compound demulsifier for oil fields.

[0048] Comparative Example 4: The proportions of the components were changed, and the rest were the same as in Example 1; the specific changes were as follows:

[0049] Step 2: Add 106 parts of 50wt% ethanol aqueous solution to the reactor, add 4 parts of sodium dodecylbenzenesulfonate, 9 parts of p-aminobenzenesulfonamide, and 7 parts of octanol in sequence while stirring, and stir for 20 minutes; add 0.1 parts of silica gel powder while stirring, heat to 60°C and stir for 15 minutes; add 8 parts of modified propylene glycol polyoxypropylene polyoxyethylene ether, 10 parts of branched demulsifier, and 6 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence while stirring, heat to 70°C and continue stirring for 30 minutes; cool, add ethanol aqueous solution to 150 parts by weight, and obtain a compound demulsifier for oil fields.

[0050] Performance test: The prepared oilfield composite demulsifier was tested for demulsification performance according to SY / T5281-2000 Crude Oil Demulsifier Performance Test Method (Bottle Test Method); the oil from an oilfield in Xinjiang Uygur Autonomous Region was used as the experimental object; the density of crude oil is 903.5 kg / m 3 , which is an intermediate-petroleum-based crude oil. The demulsifier dosage is 80 mg / L, the experimental temperature is 50°C, and the specific test data are shown in the following table:

[0051]

[0052] Conclusion: The data in the table above, including those in Examples 1 to 3, demonstrate that the introduction of modified propylene glycol polyoxypropylene polyoxyethylene ether and a small molecule additive effectively improves the dehydration efficiency of a composite demulsifier for oilfield use. Example 1 is the most optimized solution, achieving a dehydration efficiency of 63.2% after 10 minutes and 93.6% after 30 minutes. Furthermore, the water quality after dehydration is clear, demonstrating excellent demulsification performance. Comparing the data of Example 1 with the performance of Comparative Examples 2 to 4, it can be found that: in Comparative Example 1, since the propylene glycol polyoxypropylene polyoxyethylene ether was not modified, the water mass transfer rate decreased and the demulsification performance decreased; in Comparative Example 2, since the branched demulsification aid was replaced by the polyene polyamine block polyether demulsifier JMP-1 of equal mass, the demulsification and dehydration performance decreased significantly, and the water quality was significantly reduced; in Comparative Example 3, since no multiple small molecule adjuvants were introduced and only a single octanol was used, the reciprocity of the water-oil layer was reduced, resulting in a decrease in the demulsification performance; in Comparative Example 4, due to the increase in the content of the branched demulsification aid, it is sensitive to water quality, salinity, etc. compared to polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine, and the demulsification activity is limited, which reduces the performance of the demulsifier.

[0053] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A composite demulsifier for oil fields, characterized by: The compound demulsifier for oil fields comprises the following components: by weight, 8 to 10 parts of polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine, 6 to 8 parts of modified propylene glycol polyoxypropylene polyoxyethylene ether, 5 to 7 parts of branched demulsifier, 0.05 to 0.1 parts of silica gel powder, 17 to 23 parts of small molecule additives, and 102 to 114 parts of ethanol aqueous solution; The small molecule auxiliary agent comprises the following components: 3 to 5 parts of sodium dodecylbenzenesulfonate, 8 to 10 parts of p-aminobenzenesulfonamide, and 6 to 8 parts of octanol, by weight; the concentration of the ethanol aqueous solution is 40 to 50 wt%; The preparation method of the branched demulsifying agent comprises the following steps: step 1: adding catechin gallate and amino polyethylene glycol carboxyl in sequence to a methanol solvent, stirring evenly, and then removing the methanol solvent by rotary evaporation; adding formaldehyde solution under stirring, stirring evenly; heating to 80-85° C. and reacting for 8-10 hours; rotary evaporation, and low-temperature vacuum drying to obtain carboxyl branched catechin gallate; step 2: adding carboxyl branched catechin gallate and 1,2-epoxydodecane in sequence to an isopropanol solvent, heating to 70-75° C., adding N,N-dimethylbenzylamine catalyst and p-hydroxyanisole polymerization inhibitor, heating to 85-95° C. and reacting for 4-5 hours, and distilling under reduced pressure to obtain the branched demulsifying agent; The preparation method of the modified propylene glycol polyoxypropylene polyoxyethylene ether comprises the following steps: step 1: adding propylene glycol polyoxypropylene polyoxyethylene ether to a xylene solvent, heating the mixture to 50-55° C. and stirring for 10-30 minutes under a nitrogen atmosphere; adding a p-toluenesulfonic acid catalyst and dropwise adding acrylic acid; heating the mixture to 110-115° C. and reacting for 7-8 hours to obtain an esterification product; and step 2: adding the esterification product to a xylene solvent, adding a benzoyl peroxide initiator, heating the mixture to 60-90° C. and reacting for 2-6 hours, and evaporating the solvent to obtain the modified propylene glycol polyoxypropylene polyoxyethylene ether.

2. The composite demulsifier for oil fields according to claim 1, characterized in that: The raw materials of the carboxyl branched catechin gallate include the following substances: by weight, 4 to 5 parts of catechin gallate, 21 to 22 parts of amino polyethylene glycol carboxyl, 5 to 6 parts of formaldehyde solution, and 120 parts of methanol.

3. The composite demulsifier for oil fields according to claim 1, characterized in that: The raw materials of the branched demulsifying agent include the following substances: by weight, 5 to 5.6 parts of carboxyl branched gallic acid catechin gallate, 2.2 to 2.4 parts of 1,2-epoxydodecane, 0.24 to 0.25 parts of N,N-dimethylbenzylamine catalyst, and 0.005 to 0.008 parts of p-hydroxyanisole inhibitor.

4. The composite demulsifier for oil fields according to claim 1, characterized in that: The average molecular weight of the amino polyethylene glycol carboxyl group is less than 500 g / mol.

5. The composite demulsifier for oil fields according to claim 1, characterized in that: The molar ratio of propylene glycol polyoxypropylene polyoxyethylene ether to acrylic acid is 1:(3-3.5); p-toluenesulfonic acid accounts for 1-1.1wt% of the mass of propylene glycol polyoxypropylene polyoxyethylene ether; and benzoyl peroxide initiator accounts for 1-2wt% of the mass of the esterification product.

6. A method for preparing the composite demulsifier for oil fields according to any one of claims 1 to 5, characterized in that: The following steps are involved: Add ethanol aqueous solution to the reactor, add sodium dodecylbenzenesulfonate, p-aminobenzenesulfonamide, and octanol in sequence while stirring, and stir for 10 to 20 minutes; add silica gel powder while stirring, heat to 60 to 65°C, and stir for 10 to 15 minutes; Add modified propylene glycol polyoxypropylene polyoxyethylene ether under stirring; then add branched demulsifier and polyoxypropylene polyoxyethylene polyoxypropylene pentaethylene hexamine in sequence, raise the temperature to 70-75°C and continue stirring for 30-40 minutes; cool, add ethanol aqueous solution to obtain a compound demulsifier for oil fields.

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