Emulsifier, response agent, thickened oil viscosity reduction method and application

Abstract

The invention relates to the technical field of oilfield chemistry, and discloses an emulsifier, a response agent, a thick oil viscosity reduction method and application. The emulsifier is prepared from nano aluminum oxide, zwitterionic polyacrylamide and alkyl diethylenetriamine according to the mass ratio of 1 to (0.1 to 3) to (7 to 25); wherein the average particle size of the nano aluminum oxide is 30 to 300 nm. When the emulsifier provided by the invention is used for reducing the viscosity of the heavy oil, a stable emulsion can be obtained in the presence of CO2, quick demulsification can be realized by discharging CO2, the stability and quick response effect can still be kept after multiple cycles, and the emulsifier is particularly suitable for reducing the viscosity of the heavy oil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil field chemistry, in particular to an emulsifier and a response agent and a method for reducing viscosity of thick oil and application thereof. BACKGROUND

[0002] At present, the exploitation of oil has entered into the third stage, and the exploited crude oil is mainly thick oil. Thick oil has the characteristics of high viscosity and complex composition. Scholars have adopted different methods for reducing viscosity. Chemical viscosity reduction has great advantages in the methods for reducing viscosity of thick oil. The emulsifier matched with thick oil can greatly reduce the viscosity of thick oil.

[0003] Emulsion refers to a dispersion system in which one liquid phase is dispersed in the form of droplets in another immiscible liquid phase. The formation of this dispersion system often means a sharp increase in interfacial area and interfacial energy. In order to maintain the relative stability of the interface, it is usually necessary to add an emulsifier to reduce the interfacial tension or form an interfacial film with steric hindrance effect. The emulsifier can be a traditional surfactant, an amphiphilic polymer (high molecular surfactant) or a solid particle (solid surfactant). The emulsion stabilized by traditional surfactants or water-soluble polymers is called ordinary emulsion, and the emulsion stabilized by solid particles is called Pickering emulsion. According to the size and stability of the dispersed phase of the emulsion, the emulsion can be divided into ordinary emulsion (>0.4 μm, thermodynamic instability) and microemulsion (<0.1 μm, thermodynamic stability). Emulsion plays an important role in the field of oil exploitation, and people hope to obtain a temporarily stable emulsion so as to quickly break the emulsion and realize product separation after the emulsion plays its role. Therefore, how to balance the relationship between the long-term stability and the quick breaking of the emulsion has become the research focus of the emulsion.

[0004] The emergence of environmentally responsive emulsion systems offers a solution to this problem. Environmentally responsive emulsions refer to systems that can rapidly switch between a stable state and demulsification under minor stimuli from the external environment. In recent years, there have been many reports on research into environmentally responsive emulsions, but the stimuli used typically focus on temperature, pH, light, redox reactions, and magnetic fields. CO2 gas, as a novel stimuli, has attracted widespread attention since its initial proposal by Jessop et al. due to its advantages such as being green, pollution-free, inexpensive, readily available, and biocompatible. It has been successfully applied to the intelligent regulation of properties related to surfactants, solvents, viscoelastic fluids, polymers, emulsions, and microemulsions. The essence of CO2 response is that CO2 gas dissolves in water to form carbonic acid, thereby causing a change in the pH of the system. However, unlike traditional acid / base regulation, (1) CO2 enters the system in the form of gas and will not cause changes in the concentration of components in the system due to the introduction of solvent; (2) CO2 in the system can be removed by simply bubbling in inert gases such as N2 / Ar or air under certain conditions, and will not leave acid-base neutralization products in the system.

[0005] However, current environmentally responsive emulsions still suffer from problems such as complex emulsifier preparation, poor emulsion stability, limited number of cycles, and slow emulsification-demulsification transition, which restrict their application. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned problems existing in the prior art and to provide an emulsifier, a responsive agent, and a method and application for reducing the viscosity of heavy oil. When using the emulsifier provided by this invention to reduce the viscosity of heavy oil, a stable emulsion can be obtained in the presence of CO2. Rapid demulsification can be achieved by removing CO2. Stability and rapid response can be maintained even after multiple cycles, making it particularly suitable for reducing the viscosity of heavy oil.

[0007] To achieve the above objectives, the first aspect of the present invention provides an emulsifier comprising nano-alumina, zwitterionic polyacrylamide, and alkyl diethylenetriamine in a mass ratio of 1:(0.1-3):(7-25).

[0008] The average particle size of the nano-alumina is 30-300 nm.

[0009] A second aspect of the present invention provides the use of the emulsifier described above in reducing the viscosity of heavy oil.

[0010] A third aspect of the present invention provides a method for reducing the viscosity of heavy oil, the method comprising: mixing an emulsifier, heavy oil and carbon dioxide as described in the first aspect in a third mixture.

[0011] A fourth aspect of the present invention provides a responsive agent comprising an emulsifier as described in the first aspect.

[0012] When using the emulsifier provided by this invention for thick oil viscosity reduction, a stable emulsion can be obtained in the presence of CO2. Rapid demulsification can be achieved by removing CO2, and the stability and rapid response effect are maintained even after multiple cycles, making it particularly suitable for thick oil viscosity reduction. The responsive agent provided by this invention can achieve a rapid and repeated response to CO2. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] In a first aspect, the present invention provides an emulsifier comprising nano-alumina, zwitterionic polyacrylamide, and alkyl diethylenetriamine in a mass ratio of 1:(0.1-3):(7-25);

[0015] The average particle size of the nano-alumina is 30-300 nm.

[0016] The inventors of this invention discovered during their research that a CO2-responsive O / W type emulsion (Pickering type) can be prepared using an emulsifier with the above composition. When the emulsifier is mixed with heavy oil, a stable emulsion can be obtained in the presence of CO2, thus significantly reducing the viscosity of the heavy oil. When CO2 is removed (e.g., by introducing nitrogen gas to remove CO2), the emulsion can be rapidly and completely demulsified, and it maintains its stability and rapid response even after multiple cycles. This makes it particularly suitable for use in reducing the viscosity of heavy oil.

[0017] According to the present invention, preferably, the mass ratio of nano-alumina, zwitterionic polyacrylamide, and alkyldiethylenetriamine is 1:(0.4-2):(9-18). The mass ratio of nano-alumina to zwitterionic polyacrylamide can be 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, or 1:2. The mass ratio of nano-alumina to alkyldiethylenetriamine can be 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, or 1:18.

[0018] Preferably, the average particle size of the nano-alumina is 50-200 nm (for example, it can be 50, 80, 100, 120, 150, 180, 200, or any two of the above values ​​within a range of 50, 80, 100, 120, 150, 180, 200, or any value within a range of 50, 80, 100, 120, 150, 180, 200, or any two of the above values). The inventors of this invention have particularly discovered that, under the above conditions, the above-mentioned effects of the emulsifier can be further guaranteed. The nano-alumina can be spherical.

[0019] Preferably, the zwitterionic polyacrylamide comprises structural units derived from acrylamide, structural units derived from anionic group donors, and structural units derived from cationic group donors. There is no particular limitation on the content of these three structural units; for example, the mass ratio of structural units derived from acrylamide, structural units derived from anionic group donors, and structural units derived from cationic group donors can be 2:(0.8-1.2):(0.8-1.2). It is understood that the zwitterionic polyacrylamide is a copolymer of acrylamide, anionic donors, and cationic donors, and its structure contains both anionic and cationic groups.

[0020] Preferably, the anion donor is selected from sodium acrylate and / or acrylic acid, with sodium acrylate being the most preferred.

[0021] Preferably, the cation donor is selected from methacryloyloxyethyltrimethylammonium chloride and / or dimethylaminoethyl methacrylate, and more preferably dimethylaminoethyl methacrylate.

[0022] Preferably, the zwitterionic polyacrylamide has a weight-average molecular weight of 8 million to 10 million g / mol.

[0023] This invention does not impose any particular limitation on the specific substance of the zwitterionic polyacrylamide; it can be a commercially available product or something prepared in-house. For example, it can be purchased from Zibo Lanerqing Polymer Materials Co., Ltd.

[0024] Preferably, the alkyl group in the alkyl diethylenetriamine is a C12-C15 alkyl group, and the alkyl diethylenetriamine is preferably tetradecyl diethylenetriamine (C12-C15 alkyl group). 14 DETA).

[0025] Preferably, the emulsifier further contains a solvent, and the solvent is preferably water.

[0026] Preferably, the amount of solvent used results in a nano-alumina mass content of 0.01wt%-0.03wt%.

[0027] According to the present invention, preferably, the method for preparing the emulsifier includes: first mixing nano-alumina and an aqueous solution of zwitterionic polyacrylamide, and then second mixing with alkyl diethylenetriamine. The solvent in the emulsifier is water.

[0028] Preferably, the first mixing method includes: stirring at 23-28 °C (for example, it can be any value within the range formed by any two of the above values, such as 23, 24, 25, 26, 27, 28, and any value within the range) and 2000-6000 rpm (for example, it can be any value within the range formed by any two of the above values, such as 2000, 3000, 4000, 5000, 6000, and any value within the range) for 8-12 hours;

[0029] Preferably, the second mixing method includes stirring at 23-28 °C (for example, it can be any value within the range formed by any two of the above values, such as 23, 24, 25, 26, 27, 28, and any value within the range) and 2000-6000 rpm (for example, it can be any value within the range formed by any two of the above values, such as 2000, 3000, 4000, 5000, 6000, and any value within the range) for 20-60 minutes.

[0030] A second aspect of the present invention provides the use of the emulsifier described above in reducing the viscosity of heavy oil.

[0031] A third aspect of the present invention provides a method for reducing the viscosity of heavy oil, the method comprising: mixing an emulsifier, heavy oil and carbon dioxide as described in the first aspect in a third mixture;

[0032] Preferably, the volume ratio of emulsifier to heavy oil is 1:(0.8-2), for example, it can be 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2.

[0033] The emulsifier and heavy oil can be mixed first, and then carbon dioxide can be introduced to obtain a stable emulsion. The introduction rate is not particularly limited; for example, relative to 1L of the emulsifier and heavy oil mixture, the carbon dioxide introduction rate can be 0.2-0.5L / min. The total amount of carbon dioxide introduced relative to 1L of the emulsifier and heavy oil mixture can be 8-20L. After introduction, stirring or ultrasonic treatment (power 120-180W, time 0.5-2min) can be performed to ensure thorough and uniform mixing of the materials, while also preventing localized excessively high or low concentrations.

[0034] This invention does not impose any particular limitation on the type and properties of the heavy oil. For example, the kinematic viscosity of the heavy oil (which may be crude oil) may be 100-50000 mPa·s (e.g., it may be 100, 500, 1000, 1500, 2000, 2500, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 15000, 20000, 25000, 30000, 40000, 50000, or any value within the range formed by any two of the above values). Its density at 20°C may be (0.95-1) g·cm³. -3 .

[0035] A fourth aspect of the present invention provides a responsive agent comprising an emulsifier as described in the first aspect.

[0036] Preferably, the responsive agent further contains oil. The oil can be heavy oil, such as crude oil, with a kinematic viscosity of 100-50000 mPa·s and a density of (0.95-1) g·cm³ at 20°C. -3 .

[0037] Preferably, the emulsifier in the response agent has a volume content of 30-60 wt% (for example, it can be 30, 35, 40, 45, 55, 60, or any value within the range formed by any two of the above values).

[0038] The responder can be obtained by mixing an emulsifier and an oil. In the presence of carbon dioxide, the responder can form an emulsion, thus achieving a response to carbon dioxide. Introducing other gases (such as nitrogen) can demulsify the emulsion; after demulsification, introducing carbon dioxide again can rapidly form an emulsion. As described above, such a responder maintains stability and rapid response even after multiple cycles.

[0039] According to a particularly preferred embodiment of the present invention, the following emulsifiers further ensure that multiple cycles, stability, and rapid response can be achieved:

[0040] Nano-alumina (spherical, with an average particle size of 180-200 nm) was added to an aqueous solution of zwitterionic polyacrylamide (9.8-10 million g / mol, with sodium acrylate as the anionic donor and dimethylaminoethyl methacrylate as the cationic donor). The mixture was stirred at room temperature and 5500-6000 rpm for 11.5-12 h to ensure uniform dispersion. Then, tetradecyl diethylenetriamine was added, and the mixture was stirred at room temperature and 5500-6000 rpm for 55-60 min to obtain an emulsifier with an alumina mass concentration of 0.025-0.03 wt% and a mass ratio of nano-alumina, zwitterionic polyacrylamide, and alkyl diethylenetriamine of 1:(1.5-1.7):(15-17).

[0041] The present invention will be described in detail below through embodiments.

[0042] Unless otherwise specified, in the following examples and comparative examples, nano-alumina was purchased from Hangzhou Hengna New Materials Co., Ltd. In the following examples, the mass ratio of structural units from acrylamide, structural units from anionic group donors, and structural units from cationic group donors in the zwitterionic polyacrylamide was 2:1:1.

[0043] Example 1

[0044] Nano-sized alumina (spherical, average particle size 50 nm) was added to an aqueous solution of zwitterionic polyacrylamide (8 million g / mol, purchased from Zibo Lanerqing Polymer Materials Co., Ltd., with sodium acrylate as the anionic donor and dimethylaminoethyl methacrylate as the cationic donor). The mixture was stirred at room temperature (approximately 25°C) and 2000 rpm for 8 hours to ensure uniform dispersion. Then, tetradecyl diethylenetriamine was added, and the mixture was stirred at room temperature and 4000 rpm for 30 minutes to obtain an emulsifier with an alumina mass concentration of 0.01 wt%, a zwitterionic polyacrylamide mass concentration of 0.005 wt%, and a tetradecyl diethylenetriamine mass concentration of 0.1 wt%.

[0045] Example 2

[0046] Nano-sized alumina (spherical, average particle size 120 nm) was added to an aqueous solution of zwitterionic polyacrylamide (8 million g / mol, purchased from Zibo Lanerqing Polymer Materials Co., Ltd., with sodium acrylate as the anionic donor and dimethylaminoethyl methacrylate as the cationic donor). The solution was stirred at room temperature and 4000 rpm for 10 h to disperse it evenly. Then, tetradecyl diethylenetriamine was added and stirred at room temperature and 2000 rpm for 45 min to obtain an emulsifier with an alumina mass concentration of 0.02 wt%, a zwitterionic polyacrylamide mass concentration of 0.04 wt%, and tetradecyl diethylenetriamine mass concentration of 0.3 wt%.

[0047] Example 3

[0048] Nano-sized alumina (spherical, average particle size 200 nm) was added to an aqueous solution of zwitterionic polyacrylamide (10 million g / mol, purchased from Zibo Lanerqing Polymer Materials Co., Ltd., with sodium acrylate as the anionic donor and dimethylaminoethyl methacrylate as the cationic donor). The mixture was stirred at room temperature and 6000 rpm for 12 h to disperse it evenly. Then, tetradecyl diethylenetriamine was added and stirred at room temperature and 6000 rpm for 60 min to obtain an emulsifier with an alumina mass concentration of 0.03 wt%, a zwitterionic polyacrylamide mass concentration of 0.05 wt%, and tetradecyl diethylenetriamine mass concentration of 0.5 wt%.

[0049] Comparative Example 1

[0050] The emulsifier was prepared according to the method in Example 2, except that the average particle size of the nano-alumina used was 450 nm. The results are shown in Table 1.

[0051] Comparative Example 2

[0052] The emulsifier was prepared according to the method in Example 2, except that the zwitterionic polyacrylamide concentration was 0.001 wt%. The results are shown in Table 1.

[0053] Comparative Example 3

[0054] The emulsifier was prepared according to the method of Example 2, except that the mass concentration of tetradecyldiethylenetriamine was 0.6 wt%. The results are shown in Table 1.

[0055] Comparative Example 4

[0056] The emulsifier was prepared according to the method in Example 2, except that nano-alumina (spherical, average particle size 120 nm) was replaced with silica (spherical, average particle size 120 nm). The results are shown in Table 1.

[0057] Comparative Example 5

[0058] The emulsifier was prepared according to the method in Example 2, except that the zwitterionic polyacrylamide was replaced with anionic polyacrylamide (10 million g / mol, purchased from Zibo Lanerqing Polymer Materials Co., Ltd., with acrylic acid as the anionic donor). The results are shown in Table 1.

[0059] Test Example 1

[0060] The emulsifiers prepared in the above examples and comparative examples were used to conduct the following experiments:

[0061] The emulsifier and the substance with a kinematic viscosity of 10000 mPa·s and a density of 0.97 g·cm³ at 20°C were used. -3The crude oil was mixed at a volume ratio of 1:1, and then carbon dioxide was introduced at a rate of 0.3 L / min relative to 1 L of the emulsifier and heavy oil mixture for 40 min.

[0062] After injection, sonicate at 150W for 1 minute. Then take 300μL of the liquid and dilute it with distilled water by 1:1. Take one drop of the diluted liquid on a glass slide, gently cover it with a coverslip, adjust the focus until the image is clear, and observe whether an emulsion has formed.

[0063] Then, N2 was introduced at a rate of 0.3 L / min relative to 1 L of the emulsifier and heavy oil mixture for 40 min. Then, 300 μL was taken from the system and diluted with distilled water by 1:1. One drop of the diluted emulsion was placed on a glass slide, a coverslip was gently placed on it, the microscope was adjusted to focus until the image was clear, the morphology was observed, and the time of demulsification was recorded.

[0064] Repeat the above steps until no emulsion is formed 3.5 minutes after the carbon dioxide is introduced. Furthermore, during the test, for each emulsion formed, take 30 mL, let it stand, and observe and record the time when layering just begins; this is the settling time.

[0065] The test records are shown in Table 1. In Table 1, "whether CO2 is introduced to form an emulsion" and "whether N2 is introduced to break the emulsion" refer to whether the formation of an emulsion or the breaking of the emulsion occurs during the first introduction of CO2 and the first introduction of N2.

[0066] After emulsion formation, the emulsion was collected, and its viscosity was measured using a viscosity-temperature analyzer. Each measurement was repeated three times, and the arithmetic mean of the three results was taken. As the number of cycles increased, the viscosity value increased. The "viscosity" in Table 1 refers to the average viscosity value over these cycles. In each embodiment, the difference between the viscosity value at the last emulsion formation and the average viscosity value was no more than 15% of the average viscosity value.

[0067] "CO2 induction emulsion formation time" refers to the average time for emulsion formation after CO2 induction over these cycles. As the number of cycles increases, the "CO2 induction emulsion formation time" increases, but in each embodiment, the difference between the last CO2 induction emulsion formation time and the average CO2 induction emulsion formation time is less than 35% of the average CO2 induction emulsion formation time.

[0068] "Time to break down after N2 infusion" refers to the average time to break down over these cyclic cycles. As the number of cycles increases, the "time to break down after N2 infusion" will increase, but in each embodiment, the difference between the time to break down after the last N2 infusion and the average time to break down is within 15 seconds (which is also the maximum difference between the time to break down after N2 infusion across all cycles).

[0069] "Settlement time" refers to the average settling time over these number of cycles. As the number of cycles increases, the settling time decreases, but in each embodiment, the difference between the final settling time and the average settling time is within 2.5 hours (which is also the maximum difference in settling time across all cycles).

[0070] Table 1

[0071]

[0072]

[0073] As shown in Table 1, the viscosity reduction method provided by this invention has a significantly better viscosity reduction effect. This indicates that the specific proportions and composition of the emulsifier provided by this invention allow for better synergistic effects among the various substances, achieving optimal viscosity reduction. The emulsifier provided by this invention has good compatibility and is relatively stable. In the embodiments using this invention, a stable emulsion can be obtained in the presence of CO2. Rapid demulsification can be achieved by removing CO2, and stability and rapid response can be maintained even after multiple cycles, making it particularly suitable for viscosity reduction of heavy oils.

[0074] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An emulsifier, characterized in that, The emulsifier comprises nano-alumina, zwitterionic polyacrylamide, and alkyl diethylenetriamine in a mass ratio of 1:(0.1-3):(7-25). The average particle size of the nano-alumina is 30-300 nm.

2. The emulsifier according to claim 1, wherein, The mass ratio of nano-alumina, zwitterionic polyacrylamide and alkyl diethylenetriamine is 1:(0.4-2):(9-18).

3. The emulsifier according to claim 1 or 2, wherein, The average particle size of nano-alumina is 50-200 nm.

4. The emulsifier according to claim 1, wherein, The zwitterionic polyacrylamide includes structural units derived from acrylamide, structural units derived from anionic group donors, and structural units derived from cationic group donors. Preferably, the anion donor is selected from sodium acrylate and / or acrylic acid, and more preferably sodium acrylate; Preferably, the cation donor is selected from methacryloyloxyethyltrimethylammonium chloride and / or dimethylaminoethyl methacrylate, and more preferably dimethylaminoethyl methacrylate.

5. The method according to claim 1 or 4, wherein, The zwitterionic polyacrylamide has a weight-average molecular weight of 8 million to 10 million g / mol.

6. The emulsifier according to claim 1, wherein, The alkyl group in the alkyl diethylenetriamine is a C12-C15 alkyl group, and the alkyl diethylenetriamine is preferably tetradecyl diethylenetriamine.

7. The emulsifier according to claim 1 or 6, wherein, The emulsifier also contains a solvent, preferably water; Preferably, the amount of solvent used results in a nano-alumina mass content of 0.01wt%-0.03wt%.

8. The emulsifier according to claim 7, wherein, The method for preparing the emulsifier includes: first mixing nano-alumina and an aqueous solution of zwitterionic polyacrylamide, and then second mixing with alkyl diethylenetriamine; Preferably, the first mixing method includes: stirring at 23-28℃ and 2000-6000 rpm for 8-12 hours; Preferably, the second mixing method includes stirring at 23-28°C and 2000-6000 rpm for 20-60 minutes.

9. The use of the emulsifier according to any one of claims 1-8 in reducing the viscosity of heavy oil.

10. A method for reducing the viscosity of heavy oil, characterized in that, The method includes: a third mixing of the emulsifier, heavy oil, and carbon dioxide as described in any one of claims 1-8; Preferably, the volume ratio of emulsifier to heavy oil is 1:(0.8-2).

11. A responsive agent, characterized in that, The responsive agent contains an emulsifier as described in any one of claims 1-8.

12. The responsive agent according to claim 11, wherein, The responsive agent also contains oil; Preferably, the volume content of the emulsifier in the responsive agent is 30-60 wt%.

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