Oil-water separating agent for oil field and preparation method of oil-water separating agent

Abstract

The invention discloses an oil-water separating agent for an oil field, and relates to the technical field of oilfield chemistry. The invention discloses a water-based composite flocculant, which is prepared from the following raw materials in parts by weight: 150 to 250 parts of polyaluminum chloride, 80 to 120 parts of polyacrylamide, 50 to 100 parts of modified starch, 30 to 60 parts of sodium dodecyl benzene sulfonate, 20 to 40 parts of polyoxyethylene hydrophobic sorbitol fatty acid ester, 10 to 30 parts of simethicone, 5 to 15 parts of sodium hydroxide, 3 to 10 parts of hydrochloric acid and 300 to 500 parts of deionized water. The invention further discloses a preparation method of the oil-water separating agent for the oil field, the oil-water separating agent for the oil field and the preparation method of the oil-water separating agent remarkably improve the oil-water separating efficiency through raw material proportioning, the problem that a traditional oil-water separating agent is not ideal in separating effect is effectively solved, and the oil-water separating agent is simple in preparation process and low in cost. The oil-water separating agent has the advantages of easily available raw materials and relatively low cost, is beneficial to wide application in oilfield exploitation, reduces the exploitation cost, pays attention to the environmental protection concept in the preparation process, and avoids the generation of harmful byproducts.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, in particular to an oil-water separation agent used in oilfields and a preparation method thereof. Background Art

[0002] In the process of oilfield exploitation, oil-water separation is a crucial link, which is directly related to the quality and exploitation efficiency of crude oil. As a key chemical auxiliary agent, oil-water separator can effectively promote the separation of oil-water mixture and improve the recovery rate of crude oil. However, there are many types of oil-water separators on the market with different performances, and there are generally problems such as unsatisfactory separation effect, poor stability, and low environmental friendliness. Therefore, it is of great significance to develop an efficient, stable and environmentally friendly oil-water separator.

[0003] Specifically, traditional oil-water separators often have the problem of low separation efficiency, which leads to a large amount of water resources being wasted, and also increases the difficulty and cost of subsequent treatment. In addition, some oil-water separators will produce harmful byproducts during use, causing environmental pollution, which is not in line with the green and sustainable development concept of modern industry. Some oil-water separators are difficult to be widely used in oil field exploitation due to their complex preparation process and high cost. In addition, the existing oil-water separators also have the problem of poor applicability. Different oil field geological conditions and crude oil properties often require the use of different oil-water separators, which undoubtedly increases the complexity and cost of oil field exploitation. In this regard, we propose an oil-water separator for oil fields and a preparation method thereof. Summary of the invention

[0004] In order to solve the above technical problems, an oil-water separator for oil fields and a preparation method thereof are provided. The technical solution solves the problems that the above-mentioned traditional oil-water separators often have low separation efficiency, some oil-water separators will produce harmful by-products during use, the preparation process is complicated, the cost is high and the applicability is poor.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] An oil-water separator for oil fields is composed of the following raw materials in parts by weight: 150-250 parts of polyaluminium chloride, 80-120 parts of polyacrylamide, 50-100 parts of modified starch, 30-60 parts of sodium dodecylbenzene sulfonate, 20-40 parts of polyoxyethylene hydrophobic sorbitol fatty acid ester, 10-30 parts of dimethyl silicone oil, 5-15 parts of sodium hydroxide, 3-10 parts of hydrochloric acid and 300-500 parts of deionized water.

[0007] Preferably, the oil-water separator is specifically composed of the following raw materials in parts by weight: 200 parts of polyaluminium chloride, 100 parts of polyacrylamide, 70 parts of modified starch, 40 parts of sodium dodecylbenzene sulfonate, 30 parts of polyoxyethylene hydrophobic sorbitan fatty acid ester, 20 parts of dimethyl silicone oil, 10 parts of sodium hydroxide, 6 parts of hydrochloric acid, and 400 parts of deionized water.

[0008] Preferably, the preparation method of the polyaluminium chloride is: adding bauxite, hydrochloric acid and water in a mass ratio of 1:(2-3):(5-8) into a reaction kettle, reacting at 90-110° C. for 3-5 hours, and stirring continuously during the reaction to fully dissolve the bauxite;

[0009] After the reaction is completed, the insoluble impurities are removed by filtration to obtain a polyaluminium chloride solution, which is then concentrated to an aluminium oxide content of 20% to 30%.

[0010] Preferably, the preparation method of the polyacrylamide is as follows: adding acrylamide monomer and deionized water into a reaction container to prepare an aqueous solution with a concentration of 20%-30%, then adding 0.05%-0.15% of the mass of acrylamide monomer as an initiator ammonium persulfate, and initiating a polymerization reaction at 40-60° C. for 4-6 hours;

[0011] After the polymerization reaction is completed, the product is granulated, dried and crushed to obtain polyacrylamide powder with a molecular weight of 8 million to 12 million.

[0012] Preferably, the preparation method of the modified starch is: preparing corn starch and an appropriate amount of water into starch milk, wherein the concentration of the starch milk is 30%-40%;

[0013] Add 5%-10% sodium hydroxide solution to the starch mass, stir and alkalize at 40-60°C for 30-60 minutes;

[0014] Add 10%-20% of epichlorohydrin by weight of starch and react at 50-70°C for 2-4 hours to carry out etherification modification;

[0015] After the reaction is completed, the solution is neutralized with dilute hydrochloric acid to a pH value of 6-8, filtered, washed and dried to obtain modified starch.

[0016] Preferably, the purity of the sodium dodecylbenzene sulfonate is not less than 90%, the degree of polymerization of the polyoxyethylene segment in the polyoxyethylene hydrophobic sorbitan fatty acid ester is 20-30, and the viscosity of the dimethyl silicone oil is 500-1000 mPa·s.

[0017] A method for preparing an oil-water separation agent for oil fields comprises the following steps:

[0018] S1. Raw material preparation: 200 parts of polyaluminium chloride, 100 parts of polyacrylamide, 70 parts of modified starch, 40 parts of sodium dodecylbenzene sulfonate, 30 parts of polyoxyethylene hydrophobic sorbitan fatty acid ester, 20 parts of dimethyl silicone oil, 10 parts of sodium hydroxide, 6 parts of hydrochloric acid, and 400 parts of deionized water;

[0019] S2, preliminary dissolution: add polyaluminium chloride, sodium dodecylbenzene sulfonate, polyoxyethylene hydrophobic sorbitan fatty acid ester and sodium hydroxide into a reaction kettle, add 40%-60% of the total amount of deionized water, stir at a speed of 200-400r / min for 30-60 minutes to fully dissolve the raw materials to obtain solution A;

[0020] S3, starch gelatinization: slowly add the modified starch into solution A, increase the stirring speed to 400-600 r / min, and stir and gelatinize at 70-90°C for 30-60 minutes to form starch gelatin;

[0021] S4. Adding polymer: slowly add polyacrylamide to the starch gelatinized material, stirring while adding, maintaining the stirring speed at 300-500 r / min, and stirring for 60-90 minutes to ensure that the polyacrylamide is fully dispersed and dissolved to obtain solution B;

[0022] S5. pH adjustment: slowly add hydrochloric acid to solution B, and monitor the pH value of the solution in real time with a pH meter, and adjust the pH value of the solution to 6-8 to obtain solution C;

[0023] S6, defoaming treatment: add dimethyl silicone oil to solution C, stir at a speed of 100-300 r / min for 15-30 minutes to make it evenly dispersed in the solution, and perform defoaming treatment;

[0024] S7, water replenishment and volume adjustment: add the remaining deionized water to the solution, stir evenly, and make the total volume of the solution reach a predetermined scale to obtain a crude oil-water separation agent;

[0025] S8, filtering and removing impurities: filtering the crude oil-water separation agent through an 80-120 mesh filter to remove insoluble impurities and unreacted particles therein to obtain a finished oil-water separation agent;

[0026] S9. Quality inspection: Conduct quality inspection on the finished oil-water separation agent. Inspection items include appearance, active ingredient content, oil-water separation effect, pH value, etc.

[0027] S10. Packaging and storage: Pack the qualified oil-water separator products in sealed containers and store them in a cool, dry and well-ventilated environment.

[0028] Preferably, in step S2, the reactor is made of stainless steel, has jacket heating and cooling functions, and the stirring blades are double-layer three-blade type, the ratio of the upper blade diameter to the inner diameter of the reactor is 0.4-0.5, and the ratio of the lower blade diameter to the inner diameter of the reactor is 0.3-0.4;

[0029] During the initial dissolution process, the stirring speed and temperature can be appropriately adjusted according to the dissolution of the raw materials. When the raw materials dissolve slowly, the speed can be increased by 50-100r / min and the temperature can be increased by 5-10°C.

[0030] Preferably, the addition rate of the modified starch in step S3 is 5-10 g / min, and the modified starch needs to be sieved through a 60-80 mesh sieve before addition to prevent agglomeration;

[0031] During the gelatinization process, if the viscosity of the starch gelatinize shows abnormal changes, the stirring speed and temperature can be adjusted appropriately. When the viscosity increases, reduce the speed by 50-100r / min and increase the temperature by 3-5℃; when the viscosity decreases, increase the speed by 30-60r / min and reduce the temperature by 2-4℃.

[0032] Preferably, when adding polyacrylamide in step S4, pause for 3-5 minutes for each 20-30 g of polyacrylamide added, and continue adding after it is initially dispersed;

[0033] In order to improve the dissolution effect of polyacrylamide, it can be prepared into a 10%-15% aqueous solution before adding, and ultrasonic treatment is performed every 15-20 minutes during stirring, with an ultrasonic power of 200-300W and an ultrasonic time of 3-5 minutes.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The oil-water separator for oil fields and the preparation method thereof proposed in the present invention significantly improve the oil-water separation efficiency through the raw material ratio, effectively solve the problem of unsatisfactory separation effect of traditional oil-water separators, the preparation process of the oil-water separator is simple, the raw materials are easily available, and the cost is relatively low, which is conducive to being widely used in oil field exploitation and reducing the exploitation cost. The oil-water separator pays attention to the environmental protection concept in the preparation process, avoids the generation of harmful by-products, is highly environmentally friendly, meets the green and sustainable development requirements of modern industry, and is used in the oil field exploitation process to reduce environmental pollution and protect the ecological environment. It can adapt to the requirements of different oil field geological conditions and crude oil properties, reduce the complexity and cost caused by the use of different oil-water separators, and ensure the stability of the quality and performance of the oil-water separator by finely controlling the conditions and parameters of each step, thereby improving the reliability and service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1Prepare a flow chart for an oil-water separator for use in oil fields. DETAILED DESCRIPTION

[0037] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0038] An oil-water separation agent for oil fields, composed of the following raw materials in parts by weight: polyaluminium chloride: 150-250 parts. As a core flocculant, polyaluminium chloride is hydrolyzed in an aqueous solution to generate a multi-nuclear hydroxy complex, which has a dense positive charge and can strongly adsorb oil droplets and suspended particles, compress the double electrical layer, and promote the aggregation of tiny oil droplets into large oil droplets, thereby accelerating the oil-water separation process. In practical applications, 200 parts are often used. This amount can achieve an ideal flocculation effect under most oil field conditions, balancing separation efficiency and cost.

[0039] Polyacrylamide: 80-120 parts. This is a highly efficient coagulant. With its long-chain molecular structure, it can play a bridging role in the flocculation process, connecting multiple oil droplets and floccules, significantly increasing the size and weight of the floccules, accelerating the sedimentation rate, and improving the separation effect. Generally, 100 parts are selected, which is suitable for common oil-water systems to ensure good coagulant performance.

[0040] Modified starch: 50-100 parts. The specially modified starch has both hydrophilicity and a certain degree of lipophilicity, which can effectively adsorb the oil phase, while enhancing the viscosity and stability of the system, assisting flocculation and sedimentation, and preventing the separated oil phase from emulsifying and dispersing again. The dosage of 70 parts can better meet the actual production needs and optimize the separation process.

[0041] Sodium dodecylbenzene sulfonate: 30-60 parts. As an anionic surfactant, it can reduce the oil-water interfacial tension, make it easier for oil droplets to separate from the water phase, promote the demulsification of the oil-water emulsion system, and improve the separation efficiency. The addition amount of 40 parts is more appropriate.

[0042] Polyoxyethylene sorbitan fatty acid ester: 20-40 parts. It has good emulsification and dispersing properties, can assist other ingredients to be evenly dispersed in the system, and synergistically enhance the oil-water separation effect. Usually 30 parts can achieve a stable dispersion effect.

[0043] Dimethyl silicone oil: 10-30 parts. Mainly used to eliminate foam generated by stirring or chemical reaction, to prevent the foam from carrying oil droplets and affecting the separation effect. The amount of 20 parts can effectively maintain the foam volume of the system at a low level.

[0044] Sodium hydroxide: 5-15 parts. It is used to adjust the pH value in the system, create a suitable reaction environment, promote the hydrolysis or reaction of certain components, and ensure the stability of the separation agent. Generally, 10 parts can maintain the appropriate pH.

[0045] Hydrochloric acid: 3-10 parts. It works synergistically with sodium hydroxide to accurately adjust the pH value of the system to the optimal range (6-8) to ensure the activity and stability of each component. Usually 6 parts can meet the pH adjustment requirements.

[0046] Deionized water: 300-500 parts. As a solvent and diluent, it provides a medium for the dissolution, reaction and dispersion of each component, ensuring the fluidity and uniformity of the system. 400 parts of deionized water can make the separation agent form a stable and uniform solution.

[0047] Preparation of polyaluminium chloride: Add bauxite, hydrochloric acid and water in a specific ratio of 1:(2-3):(5-8) to a corrosion-resistant reactor. Stir continuously at 90-110°C for 3-5 hours. During this process, bauxite and hydrochloric acid react violently, aluminum ions gradually dissolve and undergo hydrolysis and polymerization. After the reaction is completed, filter while hot, use the filter medium to intercept insoluble impurities, and obtain polyaluminium chloride solution. Then use vacuum distillation or evaporation concentration technology to accurately control the alumina content at 20%-30%, ensuring that the product flocculation performance meets the standards and meets the production needs of oil-water separators.

[0048] Preparation of polyacrylamide: In a clean reaction container, prepare acrylamide monomer and deionized water into an aqueous solution with a concentration of 20%-30%, and stir thoroughly. Then add 0.05%-0.15% of the mass of acrylamide monomer as initiator ammonium persulfate, raise the temperature to 40-60°C, and initiate free radical polymerization. This process requires strict temperature control for 4-6 hours to ensure that the polymerization reaction proceeds fully to generate high molecular weight polyacrylamide. After the reaction is completed, the product is successively granulated, dried (temperature 60-80°C, duration 4-6 hours), and crushed to obtain polyacrylamide powder with a molecular weight of 8 million to 12 million. The powder has good water solubility and coagulant properties, and is one of the key components of oil-water separation agents.

[0049] Preparation of modified starch: First, mix corn starch with an appropriate amount of water to make a 30%-40% starch milk, stir evenly, add 5%-10% sodium hydroxide solution to the starch mass, heat to 40-60℃ for alkalization for 30-60 minutes to activate the starch molecules and enhance the reaction activity. Then, add 10%-20% epichlorohydrin to the starch mass, react at 50-70℃ for 2-4 hours for etherification modification, and introduce ether bonds to improve the starch lipophilicity and stability. After the reaction, neutralize with dilute hydrochloric acid to pH 6-8, and obtain modified starch after multiple filtration, washing (using deionized water, each washing ratio is 1:3-5), and drying (50-60℃, 3-5 hours). Its unique properties can effectively improve the performance of oil-water separators.

[0050] Reference Figure 1 As shown, a method for preparing an oil-water separation agent for oil fields, the process is:

[0051] S1: Careful preparation of raw materials: According to the optimized formula, accurately weigh 200 parts of polyaluminium chloride, 100 parts of polyacrylamide, 70 parts of modified starch, 40 parts of sodium dodecylbenzene sulfonate, 30 parts of polyoxyethylene hydrophobic sorbitan fatty acid ester, 20 parts of dimethyl silicone oil, 10 parts of sodium hydroxide, 6 parts of hydrochloric acid, and 400 parts of deionized water. All raw materials are strictly tested for quality to ensure that the purity, activity and other indicators meet the requirements, and to ensure product quality from the source.

[0052] S2: Efficient initial dissolution: Use a stainless steel reactor with jacket heating and cooling functions for precise temperature control. Built-in double-layer three-blade stirring blades, the ratio of the upper blade diameter to the inner diameter of the reactor is 0.4-0.5, and the lower layer is 0.3-0.4, to ensure uniform stirring. Add polyaluminum chloride, sodium dodecylbenzene sulfonate, polyoxyethylene hydrophobic sorbitan fatty acid ester and sodium hydroxide to the reactor, add 40%-60% deionized water, and stir at 200-400r / min for 30-60 minutes. During stirring, flexibly adjust the parameters according to the dissolution of the raw materials. When the dissolution is slow, appropriately increase the speed by 50-100r / min and the temperature by 5-10°C to ensure that the raw materials are fully dissolved to form solution A.

[0053] S3: Precise gelatinization of starch: After the modified starch is sieved through a 60-80 mesh sieve, slowly add solution A at a rate of 5-10g / min, and simultaneously increase the stirring speed to 400-600r / min, and heat to 70-90℃ for gelatinization for 30-60 minutes. During gelatinization, closely monitor the viscosity of the starch gelatin. If abnormal, adjust the parameters according to the viscosity change law. If the viscosity increases, reduce the speed by 50-100r / min and increase the temperature by 3-5℃; if the viscosity decreases, increase the speed by 30-60r / min and reduce the temperature by 2-4℃ to ensure the formation of stable starch gelatin.

[0054] S4: Scientific addition of polymer: Polyacrylamide is prepared into a 10%-15% aqueous solution before use to facilitate dispersion. It is slowly added to the starch gelatinized material, stirring while adding, maintaining a speed of 300-500r / min, pausing for 3-5min after adding 20-30g for preliminary dispersion and then continuing. During stirring, 200-300W ultrasonic treatment is performed for 3-5min every 15-20min to enhance the dissolution and dispersion effect. After 60-90 minutes of operation, solution B is obtained.

[0055] S5: Precise pH adjustment: Slowly add hydrochloric acid to solution B, and monitor in real time with a pH meter with an accuracy of 0.01. Dynamically adjust the dripping speed according to pH changes. When the pH deviates greatly from the target range, increase the dripping speed; when it is close to 6-8, slow down the dripping speed to 1-2 drops / minute for fine adjustment to ensure that the solution pH is accurately stable at 6-8 to form solution C.

[0056] S6: High-efficiency defoaming treatment: Add dimethyl silicone oil to solution C and stir at 100-300r / min for 15-30 minutes to make it evenly dispersed. Observe the foam elimination during the stirring process, and if necessary, appropriately extend the stirring time or increase the amount of dimethyl silicone oil to effectively eliminate the foam and optimize the stability of the system.

[0057] S7: Add water to the system and adjust the volume appropriately: Add the remaining deionized water to the system and stir evenly to make the total volume of the solution reach the predetermined scale to obtain the crude oil-water separation agent. During the water replenishment process, the flow rate and stirring intensity are strictly controlled to prevent the solution from splashing or generating too many bubbles, and to ensure that the product concentration and volume meet the standards.

[0058] S8: Strict filtration and impurity removal: The crude product is filtered through an 80-120 mesh filter, and the filter is cleaned or replaced regularly to maintain the filtration efficiency. This process effectively intercepts insoluble impurities, unreacted particles and agglomerates, ensuring the purity and stability of the finished oil-water separator.

[0059] S9: Comprehensive quality inspection: Conduct multi-dimensional quality inspection on finished products. The appearance should be a uniform transparent or translucent liquid without precipitation, stratification and suspended matter. Use chemical analysis or instrumental analysis to determine the content of effective ingredients such as polyaluminium chloride and polyacrylamide, and the deviation should be controlled within ±5%. According to the standard oil-water separation experiment, the oil-water separation effect is determined, the oil-water interface is clear, and the oil content of the water phase after separation is less than 50mg / L. The pH value detected by the pH meter should be in the range of 6-8. If any indicator does not meet the standard, immediately analyze the cause and adjust and optimize the production process.

[0060] S10: Proper packaging and storage: Qualified products are packaged in corrosion-resistant sealed containers, marked with key information such as product name, specifications, production date, shelf life, etc. Store in a cool (temperature 10-30℃), dry (relative humidity 40%-60%), well-ventilated environment, avoid direct sunlight, high temperature and humidity, and near fire and heat sources, and conduct regular spot checks to ensure stable and reliable performance of the product during the shelf life.

[0061] The use process of the present invention is: S1: careful preparation of raw materials; S2: efficient initial dissolution; S3: precise gelatinization of starch; S4: scientific addition of polymers; S5: precise pH adjustment; S6: efficient defoaming treatment; S7: reasonable water replenishment and volume setting; S8: strict filtration and impurity removal; S9: comprehensive quality inspection; S10: proper packaging and storage.

[0062] In summary, the advantages of the present invention are: the oil-water separation agent can react quickly with oil or oily substances to separate the original mixture into layers, which is convenient for separating and recovering oil substances without changing their physical and chemical properties. The preparation method is simple, easy to operate and control, and can effectively reduce production costs. In addition, the use of the separation agent can also reduce the limitations of traditional oil-water separation methods, such as reducing membrane clogging, reducing energy consumption, etc., while improving the oil-water treatment effect, meeting environmental protection requirements, and realizing the effective utilization of resources, which is of great significance to the effective development and sustainable development of oil fields.

[0063] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. An oil-water separation agent for oil fields, characterized in that: The invention is composed of the following raw materials in parts by weight: 150-250 parts of polyaluminium chloride, 80-120 parts of polyacrylamide, 50-100 parts of modified starch, 30-60 parts of sodium dodecylbenzene sulfonate, 20-40 parts of polyoxyethylene hydrophobic sorbitan fatty acid ester, 10-30 parts of dimethyl silicone oil, 5-15 parts of sodium hydroxide, 3-10 parts of hydrochloric acid and 300-500 parts of deionized water.

2. The oil-water separation agent for oil fields according to claim 1, characterized in that: The oil-water separator is specifically composed of the following raw materials in parts by weight: 200 parts of polyaluminium chloride, 100 parts of polyacrylamide, 70 parts of modified starch, 40 parts of sodium dodecylbenzene sulfonate, 30 parts of polyoxyethylene hydrophobic sorbitan fatty acid ester, 20 parts of dimethyl silicone oil, 10 parts of sodium hydroxide, 6 parts of hydrochloric acid and 400 parts of deionized water.

3. The oil-water separation agent for oil fields according to claim 1, characterized in that: The preparation method of polyaluminium chloride is as follows: bauxite, hydrochloric acid and water are added into a reaction kettle in a mass ratio of 1:(2-3):(5-8), reacted at 90-110° C. for 3-5 hours, and stirred continuously during the reaction to fully dissolve the bauxite; After the reaction is completed, the insoluble impurities are removed by filtration to obtain a polyaluminium chloride solution, which is then concentrated to an aluminium oxide content of 20% to 30%.

4. The oil-water separation agent for oil fields according to claim 1, characterized in that: The preparation method of polyacrylamide comprises: adding acrylamide monomer and deionized water into a reaction container to prepare an aqueous solution with a concentration of 20%-30%, then adding ammonium persulfate as an initiator accounting for 0.05%-0.15% of the mass of the acrylamide monomer, and initiating a polymerization reaction at 40-60° C. for 4-6 hours; After the polymerization reaction is completed, the product is granulated, dried and crushed to obtain polyacrylamide powder with a molecular weight of 8 million to 12 million.

5. The oil-water separation agent for oil fields according to claim 1, characterized in that: The preparation method of the modified starch is as follows: corn starch and an appropriate amount of water are mixed into starch milk, wherein the concentration of the starch milk is 30%-40%; Add 5%-10% sodium hydroxide solution to the starch mass, stir and alkalize at 40-60°C for 30-60 minutes; Add 10%-20% epichlorohydrin by weight of starch and react at 50-70°C for 2-4 hours for etherification modification; After the reaction is completed, the solution is neutralized with dilute hydrochloric acid to a pH value of 6-8, filtered, washed and dried to obtain modified starch.

6. The oil-water separation agent for oil fields according to claim 1, characterized in that: The purity of the sodium dodecylbenzene sulfonate is not less than 90%, the polymerization degree of the polyoxyethylene chain segment in the polyoxyethylene hydrophobic sorbitan fatty acid ester is 20-30, and the viscosity of the dimethyl silicone oil is 500-1000 mPa·s.

7. A method for preparing an oil-water separation agent for oil fields, characterized in that: The following steps are involved: S1. Raw material preparation: 200 parts of polyaluminium chloride, 100 parts of polyacrylamide, 70 parts of modified starch, 40 parts of sodium dodecylbenzene sulfonate, 30 parts of polyoxyethylene hydrophobic sorbitan fatty acid ester, 20 parts of dimethyl silicone oil, 10 parts of sodium hydroxide, 6 parts of hydrochloric acid, and 400 parts of deionized water; S2, preliminary dissolution: add polyaluminium chloride, sodium dodecylbenzene sulfonate, polyoxyethylene hydrophobic sorbitan fatty acid ester and sodium hydroxide into a reaction kettle, add 40%-60% of the total amount of deionized water, stir at a speed of 200-400r / min for 30-60 minutes to fully dissolve the raw materials to obtain solution A; S3, starch gelatinization: slowly add the modified starch into solution A, increase the stirring speed to 400-600 r / min, and stir and gelatinize at 70-90°C for 30-60 minutes to form starch gelatin; S4. Adding polymer: slowly add polyacrylamide to the starch gelatinized material, stirring while adding, maintaining the stirring speed at 300-500 r / min, and stirring for 60-90 minutes to ensure that the polyacrylamide is fully dispersed and dissolved to obtain solution B; S5. pH adjustment: slowly add hydrochloric acid to solution B, and monitor the pH value of the solution in real time with a pH meter, and adjust the pH value of the solution to 6-8 to obtain solution C; S6, defoaming treatment: add dimethyl silicone oil to solution C, stir at a speed of 100-300 r / min for 15-30 minutes to make it evenly dispersed in the solution, and perform defoaming treatment; S7, water replenishment and volume adjustment: add the remaining deionized water to the solution, stir evenly, and make the total volume of the solution reach a predetermined scale to obtain a crude oil-water separation agent; S8, filtering and removing impurities: filtering the crude oil-water separation agent through an 80-120 mesh filter to remove insoluble impurities and unreacted particles therein to obtain a finished oil-water separation agent; S9. Quality inspection: Conduct quality inspection on the finished oil-water separation agent. Inspection items include appearance, active ingredient content, oil-water separation effect, pH value, etc. S10. Packaging and storage: Pack the qualified oil-water separator products in sealed containers and store them in a cool, dry and well-ventilated environment.

8. The method for preparing an oil-water separation agent for oil fields according to claim 7, characterized in that: In step S2, the reactor is made of stainless steel and has jacket heating and cooling functions. The stirring blades are double-layer three-blade, the ratio of the upper blade diameter to the inner diameter of the reactor is 0.4-0.5, and the ratio of the lower blade diameter to the inner diameter of the reactor is 0.3-0.4; During the initial dissolution process, the stirring speed and temperature can be appropriately adjusted according to the dissolution of the raw materials. When the raw materials dissolve slowly, the speed can be increased by 50-100r / min and the temperature can be increased by 5-10°C.

9. The method for preparing an oil-water separation agent for oil fields according to claim 7, characterized in that: In step S3, the addition rate of the modified starch is 5-10 g / min, and the modified starch needs to be sieved through a 60-80 mesh sieve before addition to prevent agglomeration; During the gelatinization process, if the viscosity of the starch gelatinize shows abnormal changes, the stirring speed and temperature can be adjusted appropriately. When the viscosity increases, reduce the speed by 50-100r / min and increase the temperature by 3-5℃; when the viscosity decreases, increase the speed by 30-60r / min and reduce the temperature by 2-4℃.

10. The method for preparing an oil-water separation agent for oil fields according to claim 7, characterized in that: When adding polyacrylamide in step S4, pause for 3-5 minutes after adding 20-30g, and continue adding after it is initially dispersed; In order to improve the dissolution effect of polyacrylamide, it can be prepared into a 10%-15% aqueous solution before adding, and ultrasonic treatment is performed every 15-20 minutes during stirring, with an ultrasonic power of 200-300W and an ultrasonic time of 3-5 minutes.

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