Low-temperature demulsifier as well as preparation method and application thereof

Abstract

The invention provides a low-temperature demulsifier and a preparation method and application thereof, and belongs to the technical field of oil-water emulsion treatment, the low-temperature demulsifier has the following structure: # imgabs0 #, in which R1 and R2 are alkyl groups with C8-C18 carbon atoms; n is an integer greater than or equal to 1. The demulsifier provided by the invention is a novel amphiphilic surfactant, has high surface activity and good thermal stability, has good dispersibility in an oil phase due to two long carbon chains and a hydrophilic center, and has stronger acting force with natural interfacial active substances, so that an interfacial film composed of asphaltene is destroyed, and the demulsification process is promoted. The demulsifying agent is especially suitable for petroleum crude oil emulsion, and has the advantages of high demulsifying efficiency, small injection dosage, high demulsifying speed, obvious demulsifying effect and clear separated water phase. The method for preparing the demulsifying agent is simple in step and low in raw material price, and does not need complex separation equipment and expensive instrument equipment, so that the production cost of the demulsifying agent can be greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of oil-water emulsion processing, and in particular to a low-temperature demulsifier and a preparation method and application thereof. Background Art

[0002] Crude oil contains a large amount of non-hydrocarbon impurities and inorganic salts. At the same time, for most oil fields in my country, they have entered the middle and late stages of development. The content of colloids and asphaltene in crude oil has increased significantly, which puts higher requirements on crude oil demulsification. In fact, it is very important to demulsify crude oil. The impurities contained in crude oil will increase the operating load of the transportation equipment, and the free water in crude oil will cause certain environmental pollution problems. Demulsification of crude oil has great economic and environmental value. At present, the commonly used demulsification technologies at home and abroad include electrical demulsification, thermal demulsification, biological demulsification, mechanical demulsification, membrane separation and chemical demulsification. Among them, chemical demulsification is a commonly used demulsification method due to its advantages of fast speed and low consumption.

[0003] There are many types of chemical demulsifiers, which can be mainly divided into six types: polymer type; derivative type; compound type; high molecular demulsifier, which is mainly composed of ethylene carbonate. Compared with ethylene oxide type demulsifier, it is found that the application effect of this type of demulsifier is relatively good; multi-component type, which has a relatively wide application range and a relatively wide concentration range during use; trimer type, which is mainly composed of acrylamide and methacrylate. Demulsifiers have both hydrophilic and hydrophobic amphiphilic properties. They can be adsorbed on the oil-water interface to break the rigid interface film between natural emulsifiers and surfactants, thereby reducing the stability of the emulsion and achieving the purpose of oil-water separation. Demulsifiers have properties similar to emulsifiers, but they have high surface activity and low interfacial tension. They can replace the role of emulsifiers at the oil-water interface, thereby promoting the flocculation and aggregation of droplets. In order to destroy the interfacial film formed by the emulsifier, the demulsifier needs to have high surface activity and low interfacial tension. However, these demulsifiers have complex preparation processes, high raw material costs, and complex synthesis processes. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present application provides a low-temperature demulsifier and a preparation method and application thereof, aiming to solve the technical problems of complex demulsifier preparation process and high raw material cost.

[0005] In the first aspect, the present application provides a low-temperature demulsifier having the following structure: ; Where R1 and R2 are both C8~C 18 Alkyl groups of carbon atoms; The n is an integer greater than or equal to 1.

[0006] In the second aspect, an embodiment of the present application provides a method for preparing a low-temperature demulsifier, comprising the following steps: using vinylamine compounds and alkyl acrylates as raw materials, mixing them in a first solvent and reacting them, wherein the molar ratio of the vinylamine compounds to the alkyl acrylates is 1:(1~4), and after the reaction is completed, the excess solvent is evaporated to obtain a low-temperature demulsifier, wherein the vinylamine compounds contain two or more vinyl groups.

[0007] Preferably, the vinylamine compound is polyethylene polyamine.

[0008] Preferably, the ethyleneamine compound includes one or more of triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

[0009] Preferably, the alkyl acrylate includes one or more of octyl acrylate, dodecyl acrylate and octadecyl acrylate.

[0010] Preferably, the first solvent includes one or more of methanol, xylene and diethyl ether.

[0011] Preferably, the reaction temperature is 60-80° C. and the reaction time is 22-24 h.

[0012] In a third aspect, an embodiment of the present application provides an application of a low-temperature demulsifier in demulsifying a crude oil emulsion, comprising the following steps: dispersing the demulsifier in a second solvent to obtain a mixed solution; the mixed solution is then evenly mixed with the crude oil emulsion, heated to 50-60°C and allowed to stand for 0.5-2.5 hours, thereby completing the demulsification of the crude oil emulsion.

[0013] Preferably, the second solvent includes one or more of water, ethanol and xylene.

[0014] Preferably, the mass fraction of the demulsifier in the mixed solution is 0.2-1%; and the volume ratio of the mixed solution to the crude oil emulsion is 1:(10-20).

[0015] Different from the existing technical solutions, the beneficial effects of this application include: The demulsifier of the present application is a new type of amphiphilic surfactant with high surface activity and good thermal stability. The two long carbon chains and the hydrophilic center make it well dispersed in the oil phase, and have a stronger interaction with natural surfactants, thereby destroying the interfacial film composed of asphaltene and promoting the demulsification process. It is particularly suitable for petroleum crude oil emulsions, with high demulsification efficiency, small injection dosage, fast demulsification rate, obvious demulsification effect, and clear separated water phase. The method for preparing the demulsifier of the present application is simple in steps, the raw materials are cheap, and no complex separation equipment and expensive instruments and equipment are required, so the production cost of the demulsifier can be greatly reduced.

[0016] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 The infrared spectrum of the demulsifier prepared in Example 1; Figure 2 This is a diagram showing the demulsification performance of the demulsifier prepared in Example 1. DETAILED DESCRIPTION

[0019] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0021] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0022] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0024] Demulsifiers have similar properties to emulsifiers, but they have high surface activity and low interfacial tension. They can replace the role of emulsifiers at the oil-water interface, thereby promoting the flocculation and aggregation of droplets. In order to destroy the interfacial film formed by the emulsifier, demulsifiers need to have high surface activity and low interfacial tension. However, these demulsifiers have complex preparation processes, high raw material costs, and complex synthesis processes.

[0025] In order to solve the technical problems of complex preparation process, high raw material cost and complex synthesis process of demulsifier, the present application provides a low-temperature demulsifier having the following structure: ; Where R1 and R2 are both C8~C 18 Alkyl groups of carbon atoms; The n is an integer greater than or equal to 1.

[0026] In the technical scheme of the embodiment of the present application, the demulsifier in the present application is a new type of amphoteric surfactant (hydrophilic center and two hydrophobic long carbon chains), which has strong dispersibility, can be well dissolved in solvents such as water, ethanol, xylene, and can effectively reduce the tension of the oil-water interface. By changing the wettability, surface tension and interfacial tension of oil and water, the regulation of the oil-water interfacial tension is achieved. The demulsifier has a simple preparation process, a low demulsification temperature and a high demulsification rate. It solves the problems of long emulsification time of petroleum crude oil, large amount of chemical demulsifier, and high demulsification temperature. Compared with conventional demulsifiers, its surface activity is significantly improved. The double hydrophobic long chain gives the polymer good dispersibility in the oil phase, and also enhances the adsorption capacity of natural surface active substances.

[0027] In the second aspect, an embodiment of the present application provides a method for preparing a low-temperature demulsifier, comprising the following steps: using ethyleneamine compounds and alkyl acrylates as raw materials, mixing them in a first solvent and reacting them, and after the reaction is completed, evaporating the excess solvent to obtain a low-temperature demulsifier, wherein the ethyleneamine compounds contain two or more vinyl groups.

[0028] In the technical solution of the embodiment of the present application, the reaction equation is as follows: .

[0029] The raw materials used in the above method are cheap and easy to obtain, the reaction process is simple, and the low-temperature demulsifier can be prepared in one step. The prepared demulsifier has good demulsification performance, which solves the problems of poor demulsification performance for crude oil, high cost of demulsifier raw materials, and poor adaptability in the prior art.

[0030] Preferably, the vinylamine compound is polyethylene polyamine.

[0031] Preferably, the ethyleneamine compound includes one or more of triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

[0032] Preferably, the alkyl acrylate includes one or more of octyl acrylate, dodecyl acrylate and octadecyl acrylate.

[0033] Preferably, the first solvent includes one or more of methanol, xylene and diethyl ether.

[0034] Preferably, the molar ratio of the vinylamine compound to the alkyl acrylate is 1:(1-4).

[0035] Preferably, the reaction temperature is 60-80° C. and the reaction time is 22-24 h.

[0036] In the technical scheme of the embodiment of the present application, in order to facilitate the understanding of the reaction process of the present invention, alkyl acrylate is replaced by dodecyl acrylate, and xylene is selected as the solvent. After mixing with polyethylene polyamine, a demulsifier is prepared under set conditions. The specific steps are as follows: Polyethylene polyamine and dodecyl acrylate are mixed into xylene at room temperature, and the mixture is reacted at 60° C. for 24 hours. After the reaction, xylene is removed by rotary evaporation to obtain a product, and the reaction formula is shown in Formula I:

[0037] (I).

[0038] In a third aspect, an embodiment of the present application provides an application of a low-temperature demulsifier in demulsifying a crude oil emulsion, comprising the following steps: dispersing the demulsifier in a second solvent to obtain a mixed solution; the mixed solution is then evenly mixed with the crude oil emulsion, heated to 50-60°C and allowed to stand for 0.5-2.5 hours, thereby completing the demulsification of the crude oil emulsion.

[0039] Preferably, the second solvent includes one or more of water, ethanol and xylene.

[0040] Preferably, the mass fraction of the demulsifier in the mixed solution is 0.2-1%; and the volume ratio of the mixed solution to the crude oil emulsion is 1:(10-20).

[0041] In the technical solution of the embodiment of the present application, the demulsifier in the present application is used to demulsify the crude oil emulsion. After the demulsification is completed, the water phase is clear, the oil-water interface is clear, the demulsification efficiency is high, and the demulsification time is short.

[0042] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0043] 1. Preparation method Example 1 A method for preparing a low-temperature demulsifier is obtained by the following steps: At room temperature, add 0.02 mol of dodecyl acrylate and 0.01 mol of polyethylene polyamine into 20 mL of xylene. After mixing, react at 60°C for 24 hours. After the reaction is completed, evaporate the excess xylene to obtain a demulsifier.

[0044] Example 2 The only difference from Example 1 is that the polyethylene polyamine is replaced by tetraethylene pentamine, and the other steps and conditions are the same as those in Example 1; specifically: At room temperature, add 0.02 mol of dodecyl acrylate and 0.01 mol of tetraethylenepentamine into 20 mL of xylene. After mixing, react at 60°C for 24 hours. After the reaction is completed, evaporate the excess xylene to obtain a demulsifier.

[0045] Example 3 The only difference from Example 1 is that the polyethylene polyamine is replaced by pentaethylene hexamine, and the other steps and conditions are the same as those in Example 1; specifically: At room temperature, add 0.02 mol of dodecyl acrylate and 0.01 mol of pentaethylenehexamine into 20 mL of xylene. After mixing, react at 60°C for 24 hours. After the reaction is completed, evaporate the excess xylene to obtain a demulsifier.

[0046] Example 4 The only difference from Example 1 is that octadecyl acrylate is used as dodecyl acrylate, and the other steps and conditions are the same as those in Example 1; specifically: At room temperature, add 0.02 mol of octadecyl acrylate and 0.01 mol of polyethylene polyamine into 20 mL of xylene. After mixing, react at 60°C for 24 hours. After the reaction is completed, evaporate the excess xylene to obtain a demulsifier.

[0047] Example 5 The only difference from Example 4 is that the solvent is replaced with ether, and the other steps and conditions are the same as those in Example 4; specifically: At room temperature, add 0.02 mol of octadecyl acrylate and 0.01 mol of polyethylene polyamine into 20 mL of ether. After mixing, react at 60°C for 24 hours. After the reaction is completed, evaporate the excess ether to obtain a demulsifier.

[0048] Example 6 The demulsifier prepared in Example 1 is used in a crude oil emulsion, comprising the following steps: 150 parts by weight of crude oil were added to 350 parts by weight of deionized water, stirred and mixed, heated to 60° C., and then stirred at a speed of 11000 r / min for 20 minutes to obtain a stable water-in-oil emulsion, namely, a crude oil emulsion.

[0049] The demulsifier prepared in Example 1 was added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%, namely, Experimental Group 1. Experimental Group 1 was added to the above crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0050] Example 7 The difference between Example 7 and Example 6 is that the demulsifier prepared in Example 2 is added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%, and Experimental Group 2 is obtained. Experimental Group 2 is added to the above-mentioned crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0051] Example 8 The difference between Example 8 and Example 6 is that the demulsifier prepared in Example 3 is added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%, thereby obtaining Experimental Group 3. Experimental Group 3 is added to the above-mentioned crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0052] Example 9 The difference between Example 9 and Example 6 is that the demulsifier prepared in Example 4 is added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%, thereby obtaining Experimental Group 4. Experimental Group 4 is added to the above-mentioned crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0053] Example 10 The difference between Example 10 and Example 6 is that the demulsifier prepared in Example 5 is added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%, and Experimental Group 5 is obtained. Experimental Group 5 is added to the above-mentioned crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0054] Embodiment 11 150 parts by weight of crude oil were added to 350 parts by weight of deionized water, stirred and mixed, heated to 60° C., and then stirred at a speed of 11000 r / min for 20 minutes to obtain a stable water-in-oil emulsion.

[0055] The demulsifier prepared in Example 1 was added to xylene / ethanol (75:25) to prepare a demulsifier with a mass fraction of 1%. The obtained samples were recorded as experimental group 6. 1 volume part of the above experimental group 6 was added to 19 volume parts of crude oil emulsion and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0056] Example 12 The difference between Example 12 and Example 11 is that the demulsifier prepared in Example 1 is added to xylene / ethanol (75:25) to prepare a demulsifier with a mass fraction of 0.8%, and the obtained samples are recorded as Experimental Group 7. 1 volume part of the above-mentioned Experimental Group 7 is added to 19 volume parts of crude oil emulsion and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0057] Embodiment 13 The difference between Example 13 and Example 11 is that the demulsifier prepared in Example 1 is added to xylene / ethanol (75:25) to prepare a demulsifier with a mass fraction of 0.6%, and the obtained samples are recorded as Experimental Group 8. 1 volume part of the above-mentioned Experimental Group 8 is added to 19 volume parts of crude oil emulsion and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0058] Embodiment 14 The difference between Example 14 and Example 11 is that the demulsifier prepared in Example 1 is added to xylene / ethanol (75:25) to prepare a demulsifier with a mass fraction of 0.4%, and the obtained samples are recorded as Experimental Group 9. 1 volume part of the above-mentioned Experimental Group 9 is added to 19 volume parts of crude oil emulsion and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0059] Embodiment 15 The difference between Example 15 and Example 11 is that the demulsifier prepared in Example 1 is added to xylene / ethanol (75:25) to prepare a demulsifier with a mass fraction of 0.2%, and the obtained samples are recorded as experimental group 10. 1 volume part of the above experimental group 10 is added to 19 volume parts of crude oil emulsion and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0060] Example 16 The difference between Example 16 and Example 11 is that the demulsifier prepared in Example 1 is added to xylene / ethanol (75:25) to prepare a demulsifier with a mass fraction of 0%, and the obtained samples are recorded as experimental group 11. 1 volume part of the above experimental group 11 is added to 19 volume parts of crude oil emulsion and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0061] Embodiment 17 150 parts by weight of crude oil were added to 350 parts by weight of deionized water, stirred and mixed, heated to 60° C., and then stirred at a speed of 11000 r / min for 20 minutes to obtain a stable water-in-oil emulsion.

[0062] The demulsifier prepared in Example 1 was added into xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%.

[0063] 1 volume part of the above demulsifier was added to 19 volume parts of crude oil emulsion and then fully shaken and mixed, and then transferred to a water bath pot at a temperature of 40° C. and allowed to stand, recorded as experimental group 12, to complete the demulsification of crude oil emulsion.

[0064] Embodiment 18 The difference between Example 18 and Example 17 is that 1 volume part of the above demulsifier is added to 19 volume parts of crude oil emulsion and then fully shaken and mixed, and then transferred to a water bath at a temperature of 45° C. and allowed to stand, which is recorded as Experimental Group 13, completing the demulsification of the crude oil emulsion.

[0065] Embodiment 19 The difference between Example 19 and Example 17 is that 1 part by volume of the above demulsifier is added to 19 parts by volume of the crude oil emulsion and then fully shaken and mixed, and then transferred to a water bath at a temperature of 50° C. and allowed to stand, which is recorded as Experimental Group 14, completing the demulsification of the crude oil emulsion.

[0066] Embodiment 20 The difference between Example 20 and Example 17 is that 1 part by volume of the above demulsifier is added to 19 parts by volume of the crude oil emulsion and then fully shaken and mixed, and then transferred to a water bath at a temperature of 55° C. and allowed to stand, which is recorded as Experimental Group 15, completing the demulsification of the crude oil emulsion.

[0067] Comparative Example 1 The difference between Comparative Example 1 and Example 6 is that a commercial demulsifier RI-14A is used and added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1% to obtain Comparative Group 1. Comparative Group 1 is added to the above-mentioned crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0068] Comparative Example 2 The difference between Comparative Example 2 and Example 6 is that a commercial demulsifier PE10100 is added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1% to obtain Comparative Group 2. Comparative Group 2 is added to the above-mentioned crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0069] Comparative Example 3 The difference between Comparative Example 3 and Example 6 is that a commercial demulsifier DI-18 is used and added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%, thereby obtaining Comparative Group 3. Comparative Group 3 is added to the above-mentioned crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0070] Comparative Example 4 The difference between Comparative Example 4 and Example 6 is that a commercial demulsifier K3800 is used and added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%, thereby obtaining Comparative Group 4. Comparative Group 4 is added to the above-mentioned crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours to complete the demulsification of the crude oil emulsion.

[0071] 2. Test Method Crude oil emulsion dehydration rate test method: The crude oil emulsion dehydration rate is tested using the distillation method in GBT8929-2006.

[0072] III. Analysis of test results of various embodiments and comparative examples (1) Figure 1 The infrared spectrum of the demulsifier prepared in Example 1 is Figure 1It can be seen that: 3285.16 cm -1 The peak at 2921.67 cm -1 and 2849.21 cm -1 The peaks at 1730.98 cm correspond to the asymmetric and symmetric stretching vibrations of CH, respectively. -1 The peak at 1641.21 cm is attributed to the vibration of C=O. -1 and 724.08 cm -1 The absorption peaks at 1462.38 cm -1 The peak at 1177.26 cm is caused by the bending vibration in the CH plane. -1 A peak appears at 1048.70 cm, representing the stretching vibration of COC. -1 The peak at corresponds to the stretching vibration of CN. This indicates that the demulsifier shown in Formula I is successfully prepared by the method in Example 1.

[0073] (2) The demulsifiers prepared in Examples 1 to 5 were added to xylene / ethanol (75:25) to prepare solutions with a mass fraction of 1%, i.e., experimental groups 1 to 5; the commercial demulsifiers RI-14A were used as comparative example 1, PE10100 was used as comparative example 2, DI-18 was used as comparative example 3, and K3800 was used as comparative example 4, respectively, as comparative examples 1 to 4 for comparative experiments, and the commercial demulsifiers in the comparative examples were added to xylene / ethanol (75:25) to prepare solutions with a mass fraction of 1%, i.e., comparative groups 1 to 4.

[0074] The experimental groups 1-5 and the comparative groups 1-4 were added to the above crude oil emulsion at a volume ratio of 1:19 and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours. The dehydration rate was measured, and the results are shown in Table 1.

[0075] Table 1 Demulsification results of experimental groups 1 to 5 and comparative groups 1 to 4

[0076] Note: "Demulsifier (mg / L)" in the table refers to the concentration of demulsifier in crude oil emulsion.

[0077] It can be seen from Table 1 that the demulsifiers prepared in Examples 1 to 3 all have very good demulsification performance, but the demulsification efficiency varies due to different preparation conditions. The demulsifiers prepared in Examples 4 and 5 have slightly lower efficiency than the previous three, and cannot better interact with natural surfactants to destroy the interface film. However, compared with the commercial demulsifiers in the comparison group, the demulsification ability of the demulsifier provided by the present invention also has a better effect.

[0078] (3) Solutions of different concentrations of the demulsifier prepared in Example 1 were used to characterize the demulsification performance of demulsifiers of different concentrations in crude oil emulsions. Different weight portions of the demulsifier prepared in Example 1 were added to xylene / ethanol (75:25) to prepare demulsifiers with mass fractions of 1%, 0.8%, 0.6%, 0.4%, and 0.2%, respectively. The obtained samples were recorded as experimental groups 6-10; the blank group was 0%, and the sample was recorded as experimental group 11.

[0079] One volume portion of the above experimental groups 6 to 11 was added to 19 volumes of crude oil emulsion and then fully shaken and mixed, and then transferred to a 45°C water bath and allowed to stand for 4 hours. The dehydration rate was measured. The results are shown in Table 2 and Figure 2 shown.

[0080] Table 2 Demulsification results of experimental groups 6 to 11

[0081] Note: "Demulsifier (mg / L)" in the table refers to the concentration of demulsifier in crude oil emulsion.

[0082] As shown in Table 2, the demulsifier provided by the present invention has good demulsification performance. A demulsification efficiency of 99.85% can be achieved with 300 mg / L of demulsifier. When the concentration is 400 mg / L and 500 mg / L, the demulsification efficiency reaches 100%.

[0083] like Figure 2 As shown, after the demulsification is completed, the water phase of the demulsifier provided by the present invention is clear, the oil-water interface is clear, and the water content of the oil phase is low; the demulsifier of the present invention has high demulsification efficiency and short demulsification time.

[0084] (4) Based on the demulsifier prepared in Example 1, experimental groups 12 to 15 were established in sequence to characterize the demulsification performance of the demulsifier at different temperatures and times.

[0085] The demulsifier prepared in Example 1 was added into xylene / ethanol (75:25) to prepare a solution with a mass fraction of 1%.

[0086] 1 part by volume of the above demulsifier was added to 19 parts by volume of crude oil emulsion and then fully shaken to mix evenly, and then transferred to water baths set at different temperatures and allowed to stand. The dehydration rates were measured at 30 min, 60 min, 90 min, 120 min, 180 min and 240 min. The results are shown in Table 3.

[0087] Table 3 Demulsification results of experimental groups 12 to 15

[0088] It can be seen from Table 3 that the demulsifier provided by the present invention can achieve a demulsification efficiency of 96.57% at 45°C for 180 minutes, and a demulsification efficiency of 100% at 50°C and 55°C for 120 minutes.

[0089] Therefore, the demulsifier has a simple preparation process, low demulsification temperature, high demulsification efficiency and fast demulsification rate. The demulsifier is a new type of amphiphilic surfactant that can change the wettability, surface tension and surface tension of water. This project intends to adopt chemical demulsification technology to accelerate the demulsification speed and improve the demulsification efficiency through chemical demulsification process. Compared with conventional demulsifiers, the surface activity of this demulsifier is significantly improved. By using two long carbon chains and hydrophilic centers, its dispersibility in the W / O emulsion system is improved, and the interaction with natural surface active substances is enhanced, thereby breaking the asphaltene interface layer and accelerating demulsification.

[0090] The method of the present invention has a simple preparation process and is easy to implement. The demulsifier of the present invention can quickly demulsify a stable oil-water emulsion, and the demulsification effect is obvious, and the separated water phase is clear.

[0091] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A low-temperature demulsifier, characterized in that: It has the following structure: ； Where R1 and R2 are both C8~C 18 Alkyl groups of carbon atoms; The n is an integer greater than or equal to 1.

2. The method for preparing a low-temperature demulsifier according to claim 1, characterized in that: The method comprises the following steps: using ethyleneamine compounds and alkyl acrylate as raw materials, mixing them in a first solvent and reacting them, wherein the molar ratio of the ethyleneamine compounds to the alkyl acrylate is 1:(1-4), and after the reaction is completed, removing the excess solvent by rotary evaporation to obtain a low-temperature demulsifier; The vinylamine compound contains two or more vinyl groups.

3. The method for preparing a low-temperature demulsifier according to claim 2, characterized in that: The vinylamine compound is polyethylene polyamine.

4. The method for preparing a low-temperature demulsifier according to claim 2, characterized in that: The ethyleneamine compound includes one or more of triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

5. The method for preparing a low-temperature demulsifier according to claim 2, characterized in that: The alkyl acrylate includes one or more of octyl acrylate, dodecyl acrylate and octadecyl acrylate.

6. The method for preparing a low-temperature demulsifier according to claim 2, characterized in that: The first solvent includes one or more of methanol, xylene and diethyl ether.

7. The method for preparing a low-temperature demulsifier according to claim 2, characterized in that: The reaction temperature is 60~80℃ and the reaction time is 22~24h.

8. Use of a low-temperature demulsifier in crude oil emulsion demulsification according to claim 1, characterized in that: The method comprises the following steps: dispersing a demulsifier in a second solvent to obtain a mixed solution; uniformly mixing the mixed solution with a crude oil emulsion, heating the mixture to 50-60° C. and standing the mixture for 0.5-2.5 hours to complete the demulsification of the crude oil emulsion.

9. Use of the low-temperature demulsifier according to claim 8 in demulsifying crude oil emulsion, characterized in that: The second solvent includes one or more of water, ethanol and xylene.

10. Use of the low-temperature demulsifier according to claim 8 in demulsifying crude oil emulsion, characterized in that: The mass fraction of the demulsifier in the mixed solution is 0.2-1%; the volume ratio of the mixed solution to the crude oil emulsion is 1:(10-20).

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