Evaluation method for demulsification performance of cationic aromatic side chain demulsifier

Abstract

The invention relates to a method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier, which comprises the following steps: S1, synthesizing 4-bromobutyltriethylammonium bromide, 4-bromobutylbenzalkonium bromide and 4-bromobutylquinolammonium bromide, then taking polysuccinimide as a main chain, and synthesizing target products including triethylamine-polysuccinimide, N, N-dimethyl formamide and N, N-dimethyl formamide through chemical modification; the catalyst is N, N-dimethyl benzylamine-polysuccinimide, and quinoline-polysuccinimide. According to the evaluation method for the demulsification performance of the cationic aromatic side chain demulsifier, the synthesized TEA-PS I, BZK-PS I and QA-PS I demulsifiers can efficiently demulsify under different pH value conditions, especially under an acidic condition (such as pH = 2.0), the demulsification effect is particularly remarkable, in practical application, the demulsification effect can be ensured even under a severe condition, and the demulsifiers not only can effectively demulsify, but also can effectively improve the demulsification performance of the cationic aromatic side chain demulsifier. The scale formation can be inhibited to a certain extent, so that the equipment corrosion is reduced, the service life of the equipment is prolonged, the production cost is reduced, and meanwhile, good biocompatibility and environmental friendliness are realized.

Description

Technical Field

[0001] The invention relates to the technical field of demulsification performance evaluation, in particular to a method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier. Background Art

[0002] The natural active substances in crude oil mainly include asphaltene, colloid, cyclohexane acid, carbonate and solid particles (clay or wax). The presence of these natural active substances and the effect of shear force inevitably lead to the production of a large number of crude oil emulsions. In recent years, with the development and application of tertiary oil recovery technology, the content of asphaltene and colloid, the main factors affecting the stability of emulsions in crude oil, has continued to increase, which not only makes the performance of crude oil emulsions more stable, but also always causes problems such as equipment corrosion, greatly increasing the cost of production and operation, and untreated wastewater will endanger human health and the social environment. Therefore, the preparation of a low-temperature, efficient and environmentally friendly demulsifier for O / W emulsions has become an urgent problem to be solved. The current demulsification technologies include physical demulsification, chemical demulsification and biological demulsification. Among them, chemical demulsification technology has the advantages of high efficiency, flexibility, controllability, multi-function and economy, and is currently the most commonly used demulsification method.

[0003] With the development and application of tertiary oil recovery technology, the content of asphaltene and colloids in crude oil, which are the main factors affecting the stability of emulsions, continues to increase, which not only makes the performance of crude oil emulsions more stable, but also brings problems such as equipment corrosion, and increases the cost of production and operation. Therefore, traditional demulsification technology may be inefficient under low temperature conditions, especially in the demulsification process of oil / water (O / W) type crude oil emulsions. Secondly, untreated or improperly treated emulsions may cause harm to the environment, such as equipment corrosion and environmental pollution. At the same time, traditional demulsifiers may be expensive and may increase the cost of production and operation during the treatment process. Some demulsifiers may only be effective for specific types of emulsions and lack versatility. Some demulsifiers may not work well under extreme pH values ​​or other environmental conditions. The present invention aims to overcome the limitations of the prior art and provide a more effective, more environmentally friendly, and more cost-effective demulsifier, as well as a comprehensive evaluation method to ensure that its performance meets the needs of industrial applications. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier, which has the advantages of being more effective, more environmentally friendly, and more cost-effective. It solves the problems that some demulsifiers may only be effective for specific types of emulsions, lack versatility, and some demulsifiers may not be effective under extreme pH values ​​or other environmental conditions.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier, comprising the following steps:

[0006] S1. Synthesize 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br), and then use polysuccinimide (PSI) as the main chain to synthesize the target products triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI) through chemical modification;

[0007] S2, using infrared spectroscopy to determine whether the synthesized product contains the expected functional groups, and then using nuclear magnetic resonance hydrogen spectrum to verify the structural integrity of the product;

[0008] S3. The demulsification ability of different doses of demulsified sample solutions on O / W crude oil emulsions was evaluated by bottle test method, the demulsification efficiency under different pH conditions was determined, and the demulsification efficiency of demulsifiers under different grafting rates was determined;

[0009] S4, calculating the grafting ratio of products at different grafting ratios by hydrogen nuclear magnetic resonance spectrum, and calculating the HLB value of the demulsifier based on the grafting ratio;

[0010] S5. Evaluate the scale inhibition performance of demulsifier through static scale inhibition test;

[0011] S6. Determine the interfacial tension of the demulsifier at the oil-water interface using the hanging drop method;

[0012] S7. Observe the microscopic morphology changes of the emulsion during the demulsification process using a polarizing microscope.

[0013] Further, the steps of synthesizing 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br) in step S1 are as follows:

[0014] 1) Prepare the raw materials: add 13 ml of 1,4-dibromobutane into a double-necked round-bottom flask equipped with a cooling system, and purge the system with nitrogen;

[0015] 2) Adding an amine compound: slowly add 3 ml of N,N-dimethylbenzylamine into 50 ml of acetonitrile;

[0016] 3) Heating reaction: Heat the mixture to 50°C, stir for 16 hours, and then reflux for 1 hour;

[0017] 4) Isolation of the product: The product was precipitated by adding acetone to the reaction mixture, followed by freeze drying.

[0018] Furthermore, the steps of chemical modification synthesis in step S1 are as follows:

[0019] 1) Dissolve PSI in a suitable organic solvent to prepare the monomer for grafting;

[0020] 2) The dissolved PSI solution was added to the reaction bottles containing 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br), and an appropriate amount of potassium carbonate catalyst was added to promote the grafting reaction;

[0021] 3) After the reaction is completed, a non-polar solvent such as acetone or ether is added to precipitate the product so that the product is precipitated from the solution;

[0022] 4) filtering and collecting the precipitate, and then washing it several times with a solvent to remove unreacted monomers and other impurities;

[0023] 5) The product is placed in a vacuum drying oven and dried to obtain pure target products triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI).

[0024] Furthermore, the use of infrared spectra in S2 to determine whether the synthetic product contains the expected functional groups is specifically as follows: the infrared spectrum of the synthetic product is compared with a known standard spectrum to find the position and intensity of the characteristic absorption peak, the absorption peaks in the infrared spectrum are used to identify the functional groups in the product, and the changes in specific absorption peaks in the infrared spectrum are observed to verify the grafting reaction.

[0025] Furthermore, in step S2, the infrared spectra of triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI) are compared with the spectrum of the original PSI. The appearance of a new absorption peak at a specific wave number or the change in the intensity of the original absorption peak indicates that the grafting reaction is successful.

[0026] Furthermore, the structural integrity of the product is verified by using hydrogen nuclear magnetic resonance spectrum:

[0027] 1) For each synthetic product triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), quinoline-polysuccinimide (QA-PSI), record its 1 H NMR spectrum;

[0028] 2) The product 1 The H NMR spectrum is compared with the standard spectrum or the theoretically predicted spectrum to identify the characteristic peaks of each major proton;

[0029] 3) Analyze the peaks in the spectrum to confirm whether they conform to the expected structure;

[0030] 4) Compare the spectra of each product with the theoretical values ​​to confirm whether all expected proton peaks are present and their positions are correct;

[0031] 5) The grafting rate was calculated by hydrogen nuclear magnetic resonance spectrum.

[0032] Further, the step S3 is specifically as follows:

[0033] S31 selects O / W crude oil emulsion as the experimental object, sets different pH conditions according to needs, prepares demulsifier solutions of different concentrations, and selects demulsifier samples with different grafting rates;

[0034] S32 adds a selected concentration of demulsifier to a certain volume of O / W crude oil emulsion for mixing, allows the mixture to stand, allows the demulsification process to occur, and records the demulsification effect;

[0035] S33 calculates the demulsification efficiency according to the reduction degree of oil content in the water phase, and compares the demulsification efficiency of demulsifiers on emulsions at different dosages, different pH conditions and different grafting rates.

[0036] Further, the grafting rate formula of step S4 is:

[0037] Grafting rate = integrated area of ​​proton peak of grafted part / total integrated area of ​​all proton peaks in polymer × 100%;

[0038] The calculation formula of the HLB value in step S4 can be expressed as:

[0039] HLB=∑(contribution value of the hydrophilic group)-∑(contribution value of the hydrophobic group)+correction value.

[0040] Further, the specific steps of step S5 are as follows:

[0041] S51 is configured with a solution containing a certain concentration of calcium sulfate (CaSO4) as the source of simulated scaling substances;

[0042] S52 adding demulsifiers of different concentrations to the above solution to form a series of demulsifier solutions with different dosages;

[0043] S53 placing the above solution under static conditions, i.e., in a non-flowing state, to simulate the scale inhibition environment in actual working conditions;

[0044] S54 After a certain period of time, the precipitation of calcium sulfate was observed and recorded, and the scale inhibition performance of the demulsifier was evaluated by comparing the blank control group without demulsifier and the test group with demulsifier;

[0045] The S55 quantifies the amount of calcium sulfate precipitation by turbidity measurement or gravimetric method, and then calculates the scale inhibition efficiency.

[0046] Further, the formula for calculating the interfacial tension in step S6 is:

[0047] Where P is the pressure difference of the oil droplet, Dmax and Dmin are the maximum and minimum diameters of the oil droplet, respectively.

[0048] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0049] The evaluation method of the demulsification performance of the cationic aromatic side chain demulsifier is that the synthesized TEA-PSI, BZK-PSI and QA-PSI demulsifiers can effectively demulsify under different pH conditions, especially under acidic conditions (such as pH=2.0), the demulsification effect is particularly significant, and in practical applications, the demulsification effect can be guaranteed even under harsh conditions. The demulsifier can not only effectively demulsify, but also inhibit the formation of scale to a certain extent, thereby reducing equipment corrosion, extending the service life of equipment, and reducing production costs. At the same time, it has good biocompatibility and environmental friendliness, can effectively demulsify at low temperatures, and avoids the environmental pollution problems that may be caused by traditional demulsifiers. By adjusting the grafting rate and optimizing the formula, the dosage of the demulsifier can be reduced, thereby reducing the demulsification treatment cost. The demulsifier can maintain good demulsification performance under different pH conditions, is suitable for a variety of working conditions, and provides The application scope of the demulsifier is improved, the product is characterized by means of nuclear magnetic resonance hydrogen spectrum and infrared spectrum to ensure the structural integrity of the synthetic product, simplify the experimental operation process, and observe the microscopic morphology changes of the emulsion during the demulsification process through a polarizing microscope, revealing the action mechanism of the demulsifier and providing a theoretical basis for the design of the demulsifier. It is found through static scale inhibition test that BZK-PSI has outstanding performance in scale inhibition. The benzene ring functional groups contained in it can effectively disperse and stabilize metal ions and reduce scale formation. The interfacial tension of the demulsifier at the oil-water interface is significantly reduced, which is helpful for the demulsification process. Through a series of experimental methods, such as bottle test method, static scale inhibition test, hanging drop method, etc., the various performance indicators of the demulsifier are quantitatively evaluated to ensure the effectiveness and reliability of the demulsifier. These beneficial effects jointly enhance the practical value of the demulsifier and contribute to the environmental protection and economic benefits of the crude oil processing industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the structure of the present invention;

[0051] Figure 2 It is the infrared spectra of PSI, TEA-PSI, BZK-PSI and QA-PSI of the present invention;

[0052] Figure 3is the hydrogen nuclear magnetic resonance spectrum of TEA-Br, BZK-Br and QA-Br of the present invention;

[0053] Figure 4 It is the scale inhibition efficiency of PSI, TEA-PSI, BZK-PSI and QA-PSI of the present invention. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] See also Figure 1 , a method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier in this embodiment comprises the following steps:

[0056] S1. Synthesize 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br), and then use polysuccinimide (PSI) as the main chain to synthesize the target products triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI) through chemical modification;

[0057] S2, using infrared spectroscopy to determine whether the synthesized product contains the expected functional groups, and then using nuclear magnetic resonance hydrogen spectrum to verify the structural integrity of the product;

[0058] S3. The demulsification ability of different doses of demulsified sample solutions on O / W crude oil emulsions was evaluated by bottle test method, the demulsification efficiency under different pH conditions was determined, and the demulsification efficiency of demulsifiers under different grafting rates was determined;

[0059] S4, calculating the grafting ratio of products at different grafting ratios by hydrogen nuclear magnetic resonance spectrum, and calculating the HLB value of the demulsifier based on the grafting ratio;

[0060] S5. Evaluate the scale inhibition performance of demulsifier through static scale inhibition test;

[0061] S6. Determine the interfacial tension of the demulsifier at the oil-water interface using the hanging drop method;

[0062] S7. Observe the microscopic morphology changes of the emulsion during the demulsification process using a polarizing microscope.

[0063] Wherein, the steps of synthesizing 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br) in step S1 are as follows:

[0064] 1) Prepare the raw materials: add 13 ml of 1,4-dibromobutane into a double-necked round-bottom flask equipped with a cooling system, and purge the system with nitrogen;

[0065] 2) Adding an amine compound: slowly add 3 ml of N,N-dimethylbenzylamine into 50 ml of acetonitrile;

[0066] 3) Heating reaction: Heat the mixture to 50°C, stir for 16 hours, and then reflux for 1 hour;

[0067] 4) Isolation of the product: The product was precipitated by adding acetone to the reaction mixture, followed by freeze drying.

[0068] The steps of chemical modification synthesis in step S1 are as follows:

[0069] 1) Dissolve PSI in a suitable organic solvent to prepare the monomer for grafting;

[0070] 2) The dissolved PSI solution was added to the reaction bottles containing 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br), and an appropriate amount of potassium carbonate catalyst was added to promote the grafting reaction;

[0071] 3) After the reaction is completed, a non-polar solvent such as acetone or ether is added to precipitate the product so that the product is precipitated from the solution;

[0072] 4) filtering and collecting the precipitate, and then washing it several times with a solvent to remove unreacted monomers and other impurities;

[0073] 5) The product is placed in a vacuum drying oven and dried to obtain pure target products triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI).

[0074] Among them, S2 uses infrared spectra to determine whether the synthetic product contains the expected functional groups. Specifically, the infrared spectrum of the synthetic product is compared with the known standard spectrum to find the position and intensity of the characteristic absorption peak, and the absorption peaks in the infrared spectrum are used to identify the functional groups in the product. The changes in specific absorption peaks in the infrared spectrum are observed to verify the grafting reaction.

[0075] Among them, in step S2, the infrared spectra of triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI) are compared with the spectrum of the original PSI. The appearance of a new absorption peak at a specific wave number or the change in the intensity of the original absorption peak indicates that the grafting reaction is successful.

[0076] Among them, the structural integrity of the product was verified by using nuclear magnetic resonance hydrogen spectrum:

[0077] 1) For each synthetic product triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), quinoline-polysuccinimide (QA-PSI), record its 1 H NMR spectrum;

[0078] 2) The product 1 The H NMR spectrum is compared with the standard spectrum or the theoretically predicted spectrum to identify the characteristic peaks of each major proton;

[0079] 3) Analyze the peaks in the spectrum to confirm whether they conform to the expected structure;

[0080] 4) Compare the spectra of each product with the theoretical values ​​to confirm whether all expected proton peaks are present and their positions are correct;

[0081] 5) The grafting rate was calculated by hydrogen nuclear magnetic resonance spectrum.

[0082] Wherein, step S3 is specifically as follows:

[0083] S31 selects O / W crude oil emulsion as the experimental object, sets different pH conditions according to needs, prepares demulsifier solutions of different concentrations, and selects demulsifier samples with different grafting rates;

[0084] S32 adds a selected concentration of demulsifier to a certain volume of O / W crude oil emulsion for mixing, allows the mixture to stand, allows the demulsification process to occur, and records the demulsification effect;

[0085] S33 calculates the demulsification efficiency according to the reduction degree of oil content in the water phase, and compares the demulsification efficiency of demulsifiers on emulsions at different dosages, different pH conditions and different grafting rates.

[0086] Wherein, the grafting rate formula of step S4 is:

[0087] Grafting rate = integrated area of ​​proton peak of grafted part / total integrated area of ​​all proton peaks in polymer × 100%;

[0088] The calculation formula of step S4HLB value can be expressed as:

[0089] HLB=∑(contribution value of the hydrophilic group)-∑(contribution value of the hydrophobic group)+correction value.

[0090] The specific steps of step S5 are as follows:

[0091] S51 is configured with a solution containing a certain concentration of calcium sulfate (CaSO4) as the source of simulated scaling substances;

[0092] S52 adding demulsifiers of different concentrations to the above solution to form a series of demulsifier solutions with different dosages;

[0093] S53 placing the above solution under static conditions, i.e., in a non-flowing state, to simulate the scale inhibition environment in actual working conditions;

[0094] S54 After a certain period of time, the precipitation of calcium sulfate was observed and recorded, and the scale inhibition performance of the demulsifier was evaluated by comparing the blank control group without demulsifier and the test group with demulsifier;

[0095] The S55 quantifies the amount of calcium sulfate precipitation by turbidity measurement or gravimetric method, and then calculates the scale inhibition efficiency.

[0096] As the dosage of demulsifier increases, its scale inhibition performance for calcium sulfate gradually increases. When the dosage is 5.0 mg / L, the scale inhibition efficiency of the three demulsifiers for calcium sulfate is about 50.0%, among which QA-PSI has the highest scale inhibition efficiency, reaching 51.6%, which is 11.1% higher than PSI. When the dosage is further increased to 10.0 mg / L, the scale inhibition efficiency of BZK-PSI can increase to about 68.0%, and when the dosage is increased to 25.0 mg / L, the scale inhibition efficiency for calcium sulfate is close to about 90.0%, and it remains almost unchanged as the dosage continues to increase.

[0097] The formula for calculating the interfacial tension in step S6 is:

[0098] I-π(D max / D min +D max / D min ), where P is the pressure difference of the oil droplet, and Dmax and Dmin are the maximum and minimum diameters of the oil droplet, respectively.

[0099] It should be noted that the interfacial tension will be different under different pH conditions. The experimental results show that at pH = 2.0, the interfacial tension value drops the most. This may be because under acidic conditions, the surface of the oil / water interface film in the emulsion is usually negatively charged, and the cationic demulsifier can better interact with the negatively charged interface film, thereby better dispersing and separating the emulsion.

[0100] Grafting rate: The grafting rate will also affect the interfacial tension. Under neutral conditions, the interfacial tension of TEA-PSI, BZK-PSI and QA-PSI demulsifiers dropped to 39.51, 37.12 and 40.10 mN / m respectively; and at pH = 2.0, the interfacial tension value dropped more, to 37.90, 36.51 and 38.73 mN / m respectively. This shows that with the increase of grafting rate, the interfacial activity of demulsifier increases.

[0101] Results Analysis

[0102] Reduction of interfacial tension: With the increase of dosage, the interfacial tension of the three demulsifiers gradually decreased, which shows that the demulsifier can effectively reduce the tension of the oil-water interface and is beneficial to the demulsification process.

[0103] Demulsifier performance: Under different pH conditions, BZK-PSI performed better in reducing interfacial tension, which may be due to the fact that it contains more benzene rings, has stronger hydrophobicity and dispersibility, and can quickly migrate to the oil-water interface and interact with it.

[0104] The beneficial effects of the above embodiments are as follows: the TEA-PSI, BZK-PSI and QA-PSI demulsifiers synthesized in the present application can demulsify efficiently under different pH conditions, especially under acidic conditions (such as pH = 2.0), the demulsification effect is particularly significant, and in practical applications, the demulsification effect can be guaranteed even under harsh conditions. The demulsifier can not only effectively demulsify, but also inhibit the formation of scale to a certain extent, thereby reducing equipment corrosion, extending the service life of equipment, and reducing production costs. At the same time, it has good biocompatibility and environmental friendliness, can demulsify efficiently at low temperatures, and avoids the environmental pollution problems that may be caused by traditional demulsifiers. By adjusting the grafting rate and optimizing the formula, the dosage of the demulsifier can be reduced, thereby reducing the demulsification treatment cost. The demulsifier can maintain good demulsification performance under different pH conditions, is suitable for a variety of working conditions, and improves the demulsification performance. The applicable scope of the emulsion, the product was characterized by means of nuclear magnetic resonance hydrogen spectrum and infrared spectrum to ensure the structural integrity of the synthetic product, simplify the experimental operation process, and observe the microscopic morphology changes of the emulsion during the demulsification process through a polarizing microscope, revealing the action mechanism of the demulsifier, and providing a theoretical basis for the design of the demulsifier. Through the static scale inhibition test, it was found that BZK-PSI has outstanding scale inhibition performance. The benzene ring functional groups it contains can effectively disperse and stabilize metal ions and reduce scale formation. The interfacial tension of the demulsifier at the oil-water interface is significantly reduced, which is helpful for the demulsification process. Through a series of experimental methods, such as bottle test method, static scale inhibition test, hanging drop method, etc., the various performance indicators of the demulsifier are quantitatively evaluated to ensure the effectiveness and reliability of the demulsifier. These beneficial effects have jointly improved the practical value of the demulsifier and contributed to the environmental protection and economic benefits of the crude oil processing industry.

[0105] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0106] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier, characterized in that: The following steps are involved: S1. Synthesize 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br), and then use polysuccinimide (PSI) as the main chain to synthesize the target products triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI) through chemical modification; S2, using infrared spectroscopy to determine whether the synthesized product contains the expected functional groups, and then using nuclear magnetic resonance hydrogen spectrum to verify the structural integrity of the product; S3. The demulsification ability of different doses of demulsified sample solutions on O / W crude oil emulsions was evaluated by bottle test method, the demulsification efficiency under different pH conditions was determined, and the demulsification efficiency of demulsifiers under different grafting rates was determined; S4, calculating the grafting ratio of products at different grafting ratios by hydrogen nuclear magnetic resonance spectrum, and calculating the HLB value of the demulsifier based on the grafting ratio; S5. Evaluate the scale inhibition performance of demulsifier through static scale inhibition test; S6. Determine the interfacial tension of the demulsifier at the oil-water interface using the hanging drop method; S7. Observe the microscopic morphology changes of the emulsion during the demulsification process using a polarizing microscope.

2. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: The steps of synthesizing 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br) in step S1 are as follows: 1) Prepare the raw materials: add 13 ml of 1,4-dibromobutane into a double-necked round-bottom flask equipped with a cooling system, and purge the system with nitrogen; 2) Adding an amine compound: slowly add 3 ml of N,N-dimethylbenzylamine into 50 ml of acetonitrile; 3) Heating reaction: Heat the mixture to 50°C, stir for 16 hours, and then reflux for 1 hour; 4) Isolation of the product: The product was precipitated by adding acetone to the reaction mixture, followed by freeze drying.

3. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: The steps of chemical modification synthesis in step S1 are as follows: 1) Dissolve PSI in a suitable organic solvent to prepare the monomer for grafting; 2) The dissolved PSI solution was added to the reaction bottles containing 4-bromobutyltriethylammonium bromide (TEA-Br), 4-bromobutylbenzalkonium bromide (BZK-Br) and 4-bromobutylquinol ammonium bromide (QA-Br), and an appropriate amount of potassium carbonate catalyst was added to promote the grafting reaction; 3) After the reaction is completed, a non-polar solvent such as acetone or ether is added to precipitate the product so that the product is precipitated from the solution; 4) filtering and collecting the precipitate, and then washing it several times with a solvent to remove unreacted monomers and other impurities; 5) The product is placed in a vacuum drying oven and dried to obtain pure target products triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI).

4. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: The method of using the infrared spectrum in S2 to determine whether the synthetic product contains the expected functional group is as follows: comparing the infrared spectrum of the synthetic product with a known standard spectrum, finding the position and intensity of the characteristic absorption peak, using the absorption peak in the infrared spectrum to identify the functional group in the product, and observing the change of the specific absorption peak in the infrared spectrum to verify the grafting reaction.

5. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: In the step S2, the infrared spectra of triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), and quinoline-polysuccinimide (QA-PSI) are compared with the spectrum of the original PSI. The appearance of a new absorption peak at a specific wave number or the change in the intensity of the original absorption peak indicates that the grafting reaction is successful.

6. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: The structural integrity of the product is verified by using hydrogen nuclear magnetic resonance spectrum: 1) For each synthetic product triethylamine-polysuccinimide (TEA-PSI), N,N-dimethylbenzylamine-polysuccinimide (BZK-PSI), quinoline-polysuccinimide (QA-PSI), record its 1 H NMR spectrum; 2) The product 1 The H NMR spectrum is compared with the standard spectrum or the theoretically predicted spectrum to identify the characteristic peaks of each major proton; 3) Analyze the peaks in the spectrum to confirm whether they conform to the expected structure; 4) Compare the spectra of each product with the theoretical values ​​to confirm whether all expected proton peaks are present and their positions are correct; 5) The grafting rate was calculated by hydrogen nuclear magnetic resonance spectrum.

7. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: The step S3 is specifically as follows: S31 selects O / W crude oil emulsion as the experimental object, sets different pH conditions according to needs, prepares demulsifier solutions of different concentrations, and selects demulsifier samples with different grafting rates; S32 adds a selected concentration of demulsifier to a certain volume of O / W crude oil emulsion for mixing, allows the mixture to stand, allows the demulsification process to occur, and records the demulsification effect; S33 calculates the demulsification efficiency according to the reduction degree of oil content in the water phase, and compares the demulsification efficiency of demulsifiers on emulsions at different dosages, different pH conditions and different grafting rates.

8. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: The grafting rate formula of step S4 is: Grafting rate = integrated area of ​​proton peak of grafted part / total integrated area of ​​all proton peaks in polymer × 100%; The calculation formula of the HLB value in step S4 can be expressed as: HLB=∑(contribution value of the hydrophilic group)-∑(contribution value of the hydrophobic group)+correction value.

9. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: The specific steps of step S5 are as follows: S51 is configured with a solution containing a certain concentration of calcium sulfate (CaSO4) as the source of simulated scaling substances; S52 adding demulsifiers of different concentrations to the above solution to form a series of demulsifier solutions with different dosages; S53 placing the above solution under static conditions, i.e., in a non-flowing state, to simulate the scale inhibition environment in actual working conditions; S54 After a certain period of time, the precipitation of calcium sulfate was observed and recorded, and the scale inhibition performance of the demulsifier was evaluated by comparing the blank control group without demulsifier and the test group with demulsifier; The S55 quantifies the amount of calcium sulfate precipitation by turbidity measurement or gravimetric method, and then calculates the scale inhibition efficiency.

10. The method for evaluating the demulsification performance of a cationic aromatic side chain demulsifier according to claim 1, characterized in that: The formula for calculating the interfacial tension in step S6 is: Where P is the pressure difference of the oil droplet, Dmax and Dmin are the maximum and minimum diameters of the oil droplet, respectively.

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