Separation and structural characterization method of oil field demulsifier polyether

Abstract

The application belongs to the IPC classification number G01N5 / 04, and particularly relates to a separation and structural characterization method of an oil field demulsifier polyether. An oil field demulsifier polyether sample is separated by column separation or GPC separation to obtain sample components, and the sample components obtained by separation are subjected to molecular weight determination and analysis of starting species of the synthetic sample components. Through the determination method of the application, the molecular weight of the polyether can be known, and the starting agent of the synthetic polyether can also be known.

Description

TECHNICAL FIELD

[0001] The present application belongs to the IPC classification number G01N5 / 04, and specifically relates to a separation and structural characterization method of oil field demulsifier polyether. TECHNICAL BACKGROUND

[0002] In the process of oil field exploitation, some demulsifiers are added to remove the emulsified water in crude oil. At present, polyether demulsifiers are mainly used. However, due to the complexity of the components in crude oil, the dehydration effect of a single emulsifier is not ideal, and the spectrum adaptability of different types of crude oil is poor. Therefore, a compounded polyether demulsifier is often used. If the structure of the compounded polyether demulsifier can be known clearly, it is very helpful for the modification of the subsequent demulsifier.

[0003] The analysis method of GPC in patent CN109917029A can determine the functionality distribution of aliphatic polyether polyol. However, the resolution of the GPC method is low, especially for some polyethers with small molecular weight, and the accuracy of the test results is low. SUMMARY

[0004] The first aspect of the present application provides a separation method of oil field demulsifier polyether. The oil field demulsifier polyether sample is separated by column separation or GPC separation to obtain sample components.

[0005] When the oil field demulsifier polyether is a solid component, the oil field demulsifier polyether sample is used as the sample to be separated.

[0006] Some oil field demulsifier polyethers may contain water and / or organic solvent components in the actual use process. In some embodiments, the oil field demulsifier polyether sample is dried to obtain the sample to be separated.

[0007] In some embodiments, the separation of the oil field demulsifier polyether further comprises preliminary qualitative analysis of the sample to be separated. In some embodiments, the method of preliminary qualitative analysis is one or more of FTIR, HNMR, MS, and Maldi-Tof, preferably FTIR. In some embodiments, the FTIR test uses a smearing method.

[0008] Column separation

[0009] The column separation refers to the separation of different types of polyethers in the sample to be separated due to the different adsorption capacities of the polyethers on the stationary phase.

[0010] GPC separation

[0011] The GPC separation is a chromatographic column with a porous gel as a carrier in a GPC instrument. The surface and interior of the gel contain a large number of cavities of different sizes which are penetrated by each other. When the sample solution of the sample to be separated flows through the chromatographic column, the sample is separated according to the molecular weight, so that the mixed components finally form different bands or zones, and the different sample components obtained by separation are collected according to the different bands or zones.

[0012] In some embodiments, the solvent used for dissolving the sample to be separated is one or more of water, methanol, chloroform and tetrahydrofuran (preferably tetrahydrofuran).

[0013] In some embodiments, in the GPC separation, the chromatographic column is S-X3 gel packing, the mobile phase is tetrahydrofuran, and the flow rate is 5-8 ml / min.

[0014] In the present application, the number of collected sample components is the number of finally formed bands or zones.

[0015] In the present application, the GPC separation is preferred.

[0016] In some embodiments, the method further comprises a step of preliminarily qualitatively determining the different sample components, and the preliminary qualitative determination method is one or more of FTIR, HNMR, MS and Maldi-Tof, preferably FTIR. The selection of FTIR can not only determine the sample to be polyether according to the characteristic peak of ether bond, but also preliminarily determine the amount of CH3 in the sample according to the peak strength. For polyether without fatty alcohol initiator, the content of CH3 corresponds to the content of PO monomer, and in the fatty alcohol initiator polyether, especially the polyether with small molecular weight, a considerable proportion of CH3 may come from the end methyl and branched methyl of the fatty alcohol.

[0017] The second aspect of the present application provides a structure characterization method of oil field demulsifier polyether, which comprises determining the molecular weight of the sample components obtained by separation and analyzing the starting species of the synthetic sample components.

[0018] Determination of molecular weight

[0019] In some embodiments, the characterization means for determining the molecular weight is one or more of MS, Maldi-Tof and GPC.

[0020] In some preferred embodiments, the characterization means for molecular weight determination is MS, Maldi-Tof, GPC combined use, in some embodiments, MS test is performed first, then Maldi-Tof test, and finally Maldi-Tof, GPC (Gel Permation Chromatograph) test is performed to determine the molecular weight of the sample component; in other embodiments, Maldi-Tof test is used to determine the molecular weight of the sample component; in other embodiments, Maldi-Tof test and GPC (Gel Permation Chromatograph) test are used to determine the molecular weight of the sample component.

[0021] MS test

[0022] MS determination uses spray (ESI) ionization source, quadrupole detector.

[0023] In some embodiments, when the adjacent characteristic peaks in the peak cluster of MS are significantly different by 14 or 16 characteristics, the molecular weight obtained by the test is the molecular weight of the sample component; when the characteristic peaks of MS are not obvious, and the peaks are very dense, Maldi-Tof test is performed again.

[0024] Maldi-Tof test

[0025] The sample component is dissolved in a solvent (selected from one or more of water, methanol, chloroform, tetrahydrofuran, acetonitrile, preferably acetonitrile) to form a sample solution with a concentration of 15-40 mg / mL, and then the sample solution is tested in the Maldi-Tof instrument.

[0026] Maldi-Tof is a matrix-assisted laser desorption ionization source, Time off light detector,

[0027] The mode of the detector in the Maldi-Tof mode is Linear mode or Reflector mode; preferably, Reflector mode is used.

[0028] In some embodiments, the sample component is tested using Linear mode and Reflector mode respectively, when the test results of Linear mode and Reflector mode are the same, Reflector mode is used to determine the molecular weight of the polyether sample; when there are peak clusters in Linear mode that do not appear in Reflector mode, Linear mode is used to determine the molecular weight of the polyether sample.

[0029] GPC test

[0030] GPC (Gel Permation Chromatograph) is a relative molecular weight determination method, that is, the molecular weight is determined by comparing the retention time of the sample to be tested with the retention time of the standard sample

[0031] In some embodiments, the standard sample for GPC test is polyethylene glycol, that is, a series of polyethylene glycol is used as a standard sample.

[0032] In some embodiments, the preparation of the standard sample solution is as follows: polyethylene glycol with Mp = 590, 610, 700, 840, 975, 985, 1000, 1050, 1150, 1500, 1670, 2010, 2200, 2500, 3300, 3770, 5250, 5800, 10225, 10730, 15000, 30000 is dissolved in tetrahydrofuran (THF) respectively as a standard sample solution, and a series of standard sample solutions with a concentration of 0.5-2 mg / mL are prepared.

[0033] The conditions for GPC test are as follows: cross-linked polystyrene gel chromatographic column, differential refractive index detector, tetrahydrofuran as mobile phase, tetrahydrofuran as mobile phase, flow rate 0.8-1.2 mL / min, column temperature: 35°C.

[0034] Specifically, the above series of standard sample solutions are analyzed one by one using the GPC test conditions, and then the sample components are dissolved in a solvent (selected from one or more of water, methanol, chloroform, tetrahydrofuran, acetonitrile, preferably tetrahydrofuran) to form a sample solution with a concentration of 15-40 mg / mL, which is then subjected to GPC test, and the molecular weight is determined by comparing the retention time of the sample solution with the retention time of the standard sample.

[0035] The inventors found that the use of MS test in the present application can better detect polyether with smaller molecular weight, but the accuracy of the determination is poor for some polyether with larger molecular weight. Then some MS tests are low in resolution and sensitivity, and theoretically the theoretical mass range of the Maldi-Tof detector has no upper limit, but in experiments it is found that some polyether sample components may not appear peaks when measured. It is found in tests that the resolution is low when using linear mode in Maldi-Tof test, which may be because the kinetic energy of the initial ion is dispersed. The reflection mode of Maldi-Tof test can significantly improve the resolution of mass spectrum, but will reduce the sensitivity of the instrument. In experiments, it is often found that polyether with higher molecular weight does not appear peaks in reflection mode. Finally, GPC can determine whether there is polyether with higher molecular weight.

[0036] In some embodiments, the sample component is a polyether synthesized from one or more initiators selected from the group consisting of fatty alcohols, glycerol, triethanolamine, trimethylolpropane, pentaerythritol, and ethylenediamine.

[0037] Analysis of the starting species used to synthesize the sample component

[0038] In some embodiments, the sample component includes a polyether synthesized from one or more initiators selected from the group consisting of fatty alcohols, glycerol, trimethylolpropane, pentaerythritol, and ethylenediamine.

[0039] In some preferred embodiments, the sample component includes a polyether synthesized from one or more initiators selected from the group consisting of fatty alcohols, glycerol, trimethylolpropane, and pentaerythritol.

[0040] The analysis step of the starting species used to synthesize the sample component includes:

[0041] (1) contacting the catalyst with an acid anhydride to obtain a mixed acid anhydride;

[0042] (2) adding the sample component to the mixed acid anhydride and refluxing to obtain an ether cleavage product;

[0043] (3) taking an appropriate amount of the ether cleavage product in a centrifuge tube, slowly adding saturated NaHCO3 aqueous solution drop by drop, and gently shaking and standing until no bubbles are generated;

[0044] (4) adding pentyl acetate to the centrifuge tube in step (3), shaking, centrifuging, and then taking the upper organic solution, and then washing the aqueous phase with pentyl acetate, and combining the organic phases;

[0045] (5) drying the organic phase using a drying agent, and then passing through a 0.2-0.3 μm filter membrane, and then using solvent-based GC-MS with extracted ion methods to qualitatively analyze the initiator derivatives in the sample component.

[0046] The catalyst in step (1) is selected from one or more of sulfuric acid, p-toluenesulfonic acid, o-toluenesulfonic acid, trifluoromethanesulfonic acid, and a blocked sulfuric acid catalyst, and is preferably p-toluenesulfonic acid. The acid anhydride in step (1) is selected from one or more of formic anhydride, acetic anhydride, propionic anhydride, tetrachlorophthalic anhydride, and phthalic anhydride, and is preferably acetic anhydride.

[0047] In some embodiments, the p-toluenesulfonic acid and acetic anhydride in the present application react as shown in Figure 1 .

[0048] In some embodiments, the weight ratio of the catalyst to the acid anhydride in step (1) is (2-3):(4-5), preferably 2.5:4.3.

[0049] In some embodiments, the conditions for the contact reaction in step (1) are 120-130°C, and the reaction is refluxed for 0.1-1h (preferably 0.3-0.8h).

[0050] The sample component in step (2) is added dropwise for 0.5h, and after the dropwise addition is completed, the reaction is refluxed at 120-130°C for 2-4h.

[0051] In some embodiments, the weight ratio of the sample component to the catalyst is (2-3):1, preferably 2.5:1.

[0052] In some embodiments, the reaction in step (2) of the analysis of the polyether initiator species occurs as shown in the following reaction scheme. Figure 2

[0053] In step (3), the appropriate amount refers to an amount that is suitable for general laboratory operations, such as 1mL, 2mL, 3mL, etc.; and the volume of the saturated NaHCO3 aqueous solution in step (3) is 1:(1-1.5) times the volume of the ether cleavage product.

[0054] In step (4), the water phase is washed with pentyl acetate for greater than or equal to 1 time.

[0055] The inventors have found that the analysis method for the polyether initiator species in the present application can accurately determine what the initiator of the sample component is, possibly because the mixed acid anhydride generated in the present application is an ether bond cleavage reagent that acetylates the monomers and initiators in the sample component that are linked by ether bonds, and through the control of the mass of the materials, the number of acetylated groups and ether bonds should be substantially equivalent, and the products after derivatization are small molecules that can be detected in GC-MS, and the GC-MS structure of the initiator derivative can determine the type of initiator in the sample component.

[0056] Advantages:

[0057] 1. In the present application, GPC separation is preferably used, which not only can well separate and purify the oilfield demulsifier polyether, but also can roughly determine the approximate range of the molecular weight of the oilfield demulsifier polyether, thereby laying a foundation for the determination of the molecular weight of each sample component, and enabling the molecular weight test method to be more simple and accurate.

[0058] ​2. The application further comprises preliminary characterization of the sample to be separated, which can preliminarily analyze whether the tested sample is a polyether sample, and can preliminarily judge the amount of CH3 in the sample according to the strength of the separation;

[0059] 3. Polystyrene is often used as a standard in the prior art, but in the present application, it is found that the molecular weight determined by using polystyrene is too high, and the inventors have unexpectedly found that the molecular weight determined by using polyethylene glycol is more accurate;

[0060] 4. In the present application, the initiator of the synthesized polyether can also be well determined, which lays a foundation for the subsequent modification synthesis of the polyether;

[0061] 5. In the present application, the product after derivatization is a small molecule, which can be detected in GC-MS, thereby further increasing the accuracy of detection. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 Chemical equation for the reaction of toluenesulfonic acid with acetic anhydride in an embodiment of the present application;

[0063] Figure 2 Chemical equation for the reaction of toluenesulfonic acid with acetic anhydride in an embodiment of the present application;

[0064] Figure 3 FTIR test result graph of sample component A in Example 1;

[0065] Figure 4 Reflection mode Maldi-Tof spectrum of sample component B in Example 1;

[0066] Figure 5 Linear mode Maldi-Tof spectrum of sample component C in Example 1;

[0067] Figure 6 Reflection mode Maldi-Tof spectrum of sample component C in Example 1;

[0068] Figure 7 GPC result graph of sample component C in Example 1. DETAILED DESCRIPTION

[0069] Example 1

[0070] The oilfield demulsifier polyether used in the present embodiment is a mixture of polyether L44 (nominal molecular weight 1850, initiator ethylene glycol) 17 wt %, polyether L44 (nominal molecular weight 1950, initiator ethylene glycol) 10 wt %, polyether L44 (nominal molecular weight 8750, initiator ethylene glycol) 8 wt %, methanol 25 wt %, and water 40 wt %.

[0071] The first aspect of this embodiment 1 provides a method for separating oilfield demulsifier polyether:

[0072] The oilfield demulsifier polyether was dried to obtain the sample to be separated (and the solid content of the oilfield demulsifier polyether was calculated to be 38.5 wt%, that is, the content of the sample component in the oilfield demulsifier polyether was 38.5 wt%).

[0073] The sample to be separated was dissolved in tetrahydrofuran and then subjected to GPC separation (GPC separation: S-X3 gel packing column, tetrahydrofuran mobile phase, flow rate 6 ml / min). The final GPC chromatogram showed 3 regions, and sample components A, B and C were collected according to the corresponding regions.

[0074] Determination of component A in sample:

[0075] FTIR testing of sample component A was performed using a smear method, and the test results are as follows: Figure 3 As shown, through Figure 3 It can be obtained that 500 cm⁻¹ is the number of associated terminal hydroxyl groups. V OH, 2800-3000 cm⁻¹, represents methyl or methylene. v CH, 1456cm-1 and 1374cm-1 represent δC-H of methyl and methylene groups, 1348cm-1, 1297cm-1, 1251cm-1 and 1111cm-1 represent ether bonds. v CO, thus we can know that component A is polyether.

[0076] Sample component A was dissolved in acetonitrile to form a sample solution A with a concentration of 16 mg / mL, which was then tested in a Maldi-Tof instrument. The Maldi-Tof instrument is a matrix-assisted laser desorption / ionization source with a time-of-flight detector. The detector mode in the Maldi-Tof instrument is reflector mode. The molecular weight of component A was found to be 2000.

[0077] The steps for analyzing the type of initiator in the synthetic sample component A include:

[0078] (1) Weigh p-toluenesulfonic acid and acetic anhydride into a three-necked flask, add a small amount of boiling stones, and reflux p-toluenesulfonic acid and acetic anhydride in an oil bath at 125°C for 0.5 h to obtain a mixed acid anhydride;

[0079] (2) Take sample component A in constant pressure separatory funnel, add sample component (0.5 h drop completion) to mixed acid anhydride, after drop completion, reflux at 125℃ for 3 h to obtain ether cleavage product;

[0080] (3) Take 2 mL ether cleavage product in centrifuge tube, add saturated 2.5 mL NaHCO3 aqueous solution drop by drop slowly, slightly shake, and place until no bubble is generated;

[0081] (4) Add 2 mL amyl acetate to centrifuge tube in step (3), shake, centrifuge, take upper organic solution, then add 1 mL amyl acetate to wash water phase, and combine organic phases;

[0082] (5) Dry organic phase using anhydrous Na2SO4 desiccant, then pass through 0.22 μm filter membrane, and send to solvent method GC-MS to qualitatively determine starting agent derivative in sample component.

[0083] The weight ratio of p-toluenesulfonic acid, acetic anhydride, and sample component A is 2.5:4.3:1; by derivative qualitative determination, it can be obtained that the starting agent for synthesizing sample component A is ethylene glycol.

[0084] Determination of sample component B:

[0085] Use smearing method to perform FTIR test on sample component B, and it can be known from FTIR test result that component B is polyether.

[0086] Dissolve sample component B into sample solution B with a concentration of 16 mg / mL using acetonitrile, and send into Maldi-Tof instrument for test, Maldi-Tof is matrix-assisted laser desorption ionization source, Time off light detector, and the mode of detector in Maldi-Tof mode is reflector mode, reflector mode Maldi-Tof spectrum is as shown in Figure 4 , and Maldi-Tof result shows that the molecular weight is in Poisson distribution, and the peak value is about 1800, that is, the molecular weight is 1800.

[0087] The steps for analyzing the type of starting agent for synthesizing sample component B include:

[0088] (1) Take p-toluenesulfonic acid and acetic anhydride in three-necked flask, add a small amount of zeolite, and reflux p-toluenesulfonic acid and acetic anhydride in oil bath pot at 125℃ for 0.5 h to obtain mixed acid anhydride;

[0089] (2) Take sample component B in constant pressure separatory funnel, add sample component (0.5h drop completion) to mixed anhydride, after drop completion, reflux reaction at 125℃ for 3h, to obtain ether cleavage product;

[0090] (3) Take 2mL ether cleavage product in centrifuge tube, add saturated 2.5mL NBHCO3 aqueous solution drop by drop slowly, slightly shake, and place until no bubble is generated;

[0091] (4) Add 2mL ethyl acetate to centrifuge tube in step (3), shake, centrifuge, take upper organic solution, then add 1mL ethyl acetate to wash water phase, and combine organic phase;

[0092] (5) Dry organic phase using anhydrous Na2SO4 drying agent, then pass through 0.22μm filter membrane, and send to solvent method GC-MS to extract ion method to qualitatively determine starting agent derivative in sample component.

[0093] The weight ratio of p-toluenesulfonic acid, acetic anhydride and sample component B is 2.5:4.3:1; through derivative qualitative determination, it can be obtained that the starting agent for synthesizing sample component B is ethylene glycol.

[0094] Determination of sample component C:

[0095] Use smearing method to perform FTIR test on sample component C, and it can be known from FTIR test result that component C is polyether.

[0096] Dissolve sample component C into sample solution C with a concentration of 16mg / mL using acetonitrile, and send into Maldi-Tof instrument to perform test, Maldi-Tof is matrix-assisted laser desorption ionization source, Time offlight detector, the mode of detector in Maldi-Tof mode is linear mode, and linear mode Maldi-Tof spectrum is as shown in Figure 5 , and Maldi-Tof result shows that the molecular weight thereof is distributed in 7000-11000 according to the judgment;

[0097] Dissolve sample component C into sample solution C with a concentration of 16mg / mL using acetonitrile, and send into Maldi-Tof instrument to perform test, Maldi-Tof is matrix-assisted laser desorption ionization source, Time offlight detector, the mode of detector in Maldi-Tof mode is reflection mode, and reflection mode Maldi-Tof spectrum is as shown in Figure 6There is no obvious peak around 7000-11000 molecular weight, but there are two low abundance peak clusters around 1500 and 3000, which may be fragment peaks or impurity peaks;

[0098] Preparation of standard sample solution: polyethylene glycol with Mp = 590, 610, 700, 840, 975, 985, 1000, 1050, 1150, 1500, 1670, 2010, 2200, 2500, 3300, 3770, 5250, 5800, 10225, 10730, 15000, 30000 were dissolved in tetrahydrofuran (THF) respectively as standard sample solution, a series of standard sample solutions with a concentration of 1 mg / mL were prepared; the GPC test conditions were: using crosslinked polystyrene gel chromatographic column, differential refractive index detector, tetrahydrofuran as mobile phase, tetrahydrofuran as mobile phase, flow rate 1 mL / min, column temperature: 35℃; using the above GPC test conditions, the above series of standard sample solutions were analyzed one by one, then sample component C was dissolved in tetrahydrofuran to prepare a sample solution with a concentration of 16 mg / mL, and the sample solution was subjected to GPC test according to the above GPC test, the molecular weight was determined by comparing the retention time of the sample solution with the retention time of the standard sample, and the GPC result is shown in Figure 7 The molecular weight peak is about 9000.

[0099] The distribution of the spectrum obtained by the above method is that the molecular weight of sample component C is 9000 according to the GPC test.

[0100] The steps of analyzing the initiator species of the synthesized sample component C include:

[0101] (1) Weigh p-toluenesulfonic acid and acetic anhydride into a three-necked flask, add a small amount of zeolite, reflux the p-toluenesulfonic acid and acetic anhydride in the oil bath at 125℃ for 0.5h to obtain a mixed anhydride;

[0102] (2) Weigh sample component C into a constant pressure separatory funnel, add sample component to the mixed anhydride dropwise (0.5h dropwise), and then reflux at 125℃ for 3h after dropwise addition to obtain an ether cleavage product;

[0103] (3) Take 2mL of the ether cleavage product into a centrifuge tube, slowly add saturated 2.5mL NaHCO3 aqueous solution dropwise, and gently shake and stand until no bubbles are generated;

[0104] (4) Add 2mL of amyl acetate to the centrifuge tube in step (3), shake, centrifuge, and then add 1mL of amyl acetate to wash the aqueous phase, and combine the organic phases;

[0105] (5) The organic phase was dried with anhydrous Na2SO4dry reagent, then filtered through a 0.22 μm filter membrane, and sent to solvent GC-MS for qualitative analysis of the initiator derivative in the sample component by extraction ion method.

[0106] The weight ratio of p-toluenesulfonic acid, acetic anhydride, and sample component C was 2.5:4.3:1; and the initiator for synthesizing sample component C was ethylene glycol, which was determined by derivative qualitative analysis.

[0107] Example 2

[0108] Sample component A in Example 1 was dissolved into a sample solution A with a concentration of 16 mg / mL using tetrahydrofuran for GPC test, and the test conditions were the same as those in Example 1, except that water was used as the flowability, and the molecular weight of the component A sample was 1000, which was determined by the test.

[0109] Example 3

[0110] Sample component A in Example 1 was dissolved into a sample solution A with a concentration of 16 mg / mL using acetonitrile for test in a Maldi-Tof instrument, which was a Matrix-assisted laser desorption ionization source with a Time off light detector, and the detector mode in the Maldi-Tof mode was a Linear mode, and the molecular weight of the component A sample was 2000, which was determined by the test.

Claims

1. A method for structural characterization of oilfield demulsifier polyether, characterized in that, The oilfield demulsifier polyether sample was separated into sample components by column separation or GPC. Before separating the oilfield demulsifier polyether, the preliminary characterization of the sample to be separated is also included. The preliminary characterization method is one or more of FTIR, HNMR, MS, and Maldi-Tof. During the GPC separation, the chromatographic column was an S-X3 gel packing material, the mobile phase was tetrahydrofuran, and the flow rate was 5-8 mL / min. The molecular weight of each sample component was determined and the starting species used to synthesize the sample components were analyzed. The molecular weight determination is characterized by one or more of MS, Maldi-Tof, and GPC. The standard sample used in the GPC test was polyethylene glycol. The Maldi-Tof is a matrix-assisted laser desorption / ionization source and a time-of-flight detector. The detector mode in the Maldi-Tof mode is a linear mode. The sample components include polyethers synthesized from one or more initiators selected from fatty alcohols, glycerol, triethanolamine, trimethylolpropane, pentaerythritol, and ethylenediamine; The analytical steps for synthesizing sample components using starting materials include: (1) The catalyst reacts with the acid anhydride to obtain a mixed acid anhydride; (2) The sample components were added to the mixed acid anhydride and refluxed to obtain the ether cleavage product; (3) Take an appropriate amount of ether pyrolysis product into a centrifuge tube, slowly add saturated NaHCO3 aqueous solution drop by drop and shake gently until no bubbles are generated; (4) Add amyl acetate to the centrifuge tube in step (3), shake, centrifuge, aspirate the upper organic solution, then wash the aqueous phase with amyl acetate and combine the organic phases; (5) Dry the organic phase with a desiccant, then filter it through a 0.2-0.3 μm filter membrane, and send it to solvent-based GC-MS for ion extraction to characterize the initiator derivatives in the sample components; The acid anhydride is one or more of formic anhydride, acetic anhydride, propionic anhydride, tetrachlorophthalic anhydride, and phthalic anhydride; The weight ratio of the catalyst to the acid anhydride is (2-3):(4-5); The weight ratio of the sample component to the catalyst is (2-3):

1.

2. The structural characterization method for oilfield demulsifier polyether according to claim 1, characterized in that, In step (1), the catalyst is selected from one or more of sulfuric acid, p-toluenesulfonic acid, o-toluenesulfonic acid, trifluoromethanesulfonic acid, and blocked sulfuric acid catalyst.

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