Eutectic ionic liquid as well as preparation method and application thereof

Abstract

The invention provides eutectic ionic liquid and a preparation method and application thereof, the eutectic ionic liquid is binary or ternary system ionic liquid composed of a hydrogen bond donor and a hydrogen bond acceptor, the hydrogen bond donor is an amide compound, and the hydrogen bond acceptor is a metal salt hydrate. The preparation method comprises the following steps: mixing a hydrogen bond donor and a hydrogen bond acceptor, stirring and heating until a clear and transparent homogeneous solution is formed, thereby obtaining the eutectic ionic liquid. The eutectic ionic liquid provided by the invention can promote slight chemical cracking of asphaltene in thickened oil, effectively reduce the viscosity of the thickened oil and promote stripping of an oil film, so that the recovery rate of crude oil is improved, the eutectic ionic liquid is combined with water flooding, the oil-water interfacial tension can be reduced, the water flooding effect is improved, and the oil-water flooding effect is improved. And meanwhile, the eutectic ionic liquid has biodegradability, is low in production cost and is beneficial to large-scale popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of oil field development and relates to an ionic liquid, in particular to a eutectic ionic liquid and a preparation method and application thereof. Background Art

[0002] In recent years, my country has experienced a high degree of dependence on foreign crude oil, and the country boasts abundant proven, untapped, and remaining oil reserves. Even under the net-zero emissions target, the large-scale application of carbon capture and storage (CCS) means that traditional fuels like oil will continue to play a key role in the energy transition. Therefore, improving oil recovery is a perennial challenge in oilfield development and a cornerstone of my country's energy security.

[0003] Ionic liquids are substances composed of ions that are liquid at room temperature. Due to their excellent properties, such as high temperature resistance, a wide operating temperature range, non-flammability, and good solubility in many organic and inorganic compounds, they are increasingly used in catalysis and separation. As a new type of surfactant, ionic liquids can adhere to the oil-water interface, weakening and destroying the interfacial film, thereby reducing interfacial tension and altering wettability. Therefore, they also have potential applications in oil recovery.

[0004] Studies have shown that different alkyl chain lengths of the same ionic liquid have a greater effect on the oil-water interfacial tension, and the longer the alkyl chain, the more significantly it can improve the oil-water interfacial activity, thereby improving the recovery rate (Alkylation Waste Acid Treatment Technology, Li Rui, Contemporary Chemical Industry, 2020, 49 (2): 178-184). Other experiments have shown that ionic liquids can achieve the effect of reducing IFT even under high temperature and high salinity conditions, which is unattainable by traditional surfactants (Effect of different families (imidazolium and pyridinium) of ionic liquids-based surfactants on interfacialtension of water / crude oil system. AZ Hezave, S. Dorostkar, S. Ayatollahi, et al. Fluid Phase Equilibrium, 2013, 360: 139-145). However, ionic liquids have problems such as difficult biodegradation and high production costs, which hinder their application in the field of oil production.

[0005] Therefore, how to provide an ionic liquid and its preparation method to achieve targeted exploitation of heavy oil reservoirs, improve crude oil recovery, and at the same time have biodegradability and reduce production costs has become an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a low-melting ionic liquid and its preparation method and application. The low-melting ionic liquid realizes the targeted exploitation of heavy oil reservoirs, improves the crude oil recovery rate, and is biodegradable, reducing production costs, which is conducive to large-scale promotion and application.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a eutectic ionic liquid, wherein the eutectic ionic liquid is a binary or ternary ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor.

[0009] The hydrogen bond donor is an amide compound, and the hydrogen bond acceptor is a metal salt hydrate.

[0010] The present invention uses an amide compound as a hydrogen bond donor and a metal salt hydrate as a hydrogen bond acceptor. The resulting eutectic ionic liquid can promote slight chemical cracking of asphaltenes in heavy oil, effectively reducing the viscosity of the heavy oil and promoting the stripping of the oil film, thereby improving the crude oil recovery rate. Combining the eutectic ionic liquid with water flooding can reduce the oil-water interfacial tension and improve the water flooding effect. At the same time, the eutectic ionic liquid is biodegradable and has a low production cost, which is conducive to large-scale promotion and application.

[0011] Preferably, the amide compound includes any one of benzamide, phenylacetamide, terephthalamide or caprolactam, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of benzamide and phenylacetamide, a combination of phenylacetamide and terephthalamide, a combination of terephthalamide and caprolactam, a combination of benzamide, phenylacetamide and terephthalamide, a combination of phenylacetamide, terephthalamide and caprolactam, or a combination of benzamide, phenylacetamide, terephthalamide and caprolactam.

[0012] Preferably, the metal salt hydrate comprises any one or a combination of at least two of nickel chloride hexahydrate, copper chloride dihydrate, cobalt chloride hexahydrate or ferric chloride hexahydrate. Typical but non-limiting combinations include a combination of nickel chloride hexahydrate and copper chloride dihydrate, a combination of copper chloride dihydrate and cobalt chloride hexahydrate, a combination of cobalt chloride hexahydrate and ferric chloride hexahydrate, a combination of nickel chloride hexahydrate, copper chloride dihydrate and cobalt chloride hexahydrate, a combination of copper chloride dihydrate, cobalt chloride hexahydrate and ferric chloride hexahydrate, or a combination of nickel chloride hexahydrate, copper chloride dihydrate, cobalt chloride hexahydrate and ferric chloride hexahydrate.

[0013] In a second aspect, the present invention provides a method for preparing the low-melting ionic liquid as described in the first aspect, the preparation method comprising: mixing a hydrogen bond donor and a hydrogen bond acceptor, stirring and heating them until a clear and transparent homogeneous solution is formed to obtain a low-melting ionic liquid.

[0014] Preferably, the mixing molar ratio of the hydrogen bond donor and the hydrogen bond acceptor is (1-10):1, for example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, and more preferably (1-5):1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0015] Preferably, the stirring and heating method includes: magnetically stirring the mixed solution in a water bath environment.

[0016] Preferably, the stirring and heating temperature is 40-90°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C, and more preferably 60-80°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0017] Preferably, the stirring and heating time is 10-60 min, for example, it can be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, more preferably 20-40 min, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0018] As a preferred technical solution of the second aspect of the present invention, the preparation method comprises: mixing a hydrogen bond donor and a hydrogen bond acceptor in a molar ratio of (1-5):1, magnetically stirring the mixed solution in a water bath environment at 60-80°C for 20-40 minutes until a clear and transparent homogeneous solution is formed to obtain a low eutectic ionic liquid.

[0019] In a third aspect, the present invention provides a use of the eutectic ionic liquid as described in the first aspect, wherein an aqueous solution of the eutectic ionic liquid is used as a water flooding and oil displacement system.

[0020] Preferably, the concentration of the eutectic ionic liquid in the water flooding and oil displacement system is 1-10wt%, for example, it can be 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt% or 10wt%, more preferably 1-5wt%, but is not limited to the listed values, and other values ​​not listed within this numerical range are equally applicable.

[0021] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention uses an amide compound as a hydrogen bond donor and a metal salt hydrate as a hydrogen bond acceptor. The resulting eutectic ionic liquid can promote slight chemical cracking of asphaltenes in heavy oil, effectively reducing the viscosity of the heavy oil and promoting the stripping of the oil film, thereby improving the crude oil recovery rate. Combining the eutectic ionic liquid with water flooding can reduce the oil-water interfacial tension and improve the water flooding effect. At the same time, the eutectic ionic liquid is biodegradable and has a low production cost, which is conducive to large-scale promotion and application. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0025] Example 1

[0026] This embodiment provides a eutectic ionic liquid and a preparation method thereof. The eutectic ionic liquid is a binary system ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor, wherein the hydrogen bond donor is benzamide and the hydrogen bond acceptor is nickel chloride hexahydrate.

[0027] In this embodiment, the preparation method of the low-melting ionic liquid is as follows: a hydrogen bond donor and a hydrogen bond acceptor are mixed in a molar ratio of 2:1, and the mixed solution is magnetically stirred in a water bath environment at 70°C for 30 minutes until a clear and transparent homogeneous solution is formed to obtain a low-melting ionic liquid.

[0028] Example 2

[0029] This embodiment provides a eutectic ionic liquid and a preparation method thereof. The eutectic ionic liquid is a binary system ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor, wherein the hydrogen bond donor is phenylacetamide and the hydrogen bond acceptor is nickel chloride hexahydrate.

[0030] In this embodiment, the preparation method of the low-melting ionic liquid is as follows: a hydrogen bond donor and a hydrogen bond acceptor are mixed in a molar ratio of 1:1, and the mixed solution is magnetically stirred in a water bath environment at 60°C for 40 minutes until a clear and transparent homogeneous solution is formed to obtain a low-melting ionic liquid.

[0031] Example 3

[0032] This embodiment provides a eutectic ionic liquid and a preparation method thereof. The eutectic ionic liquid is a binary system ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor, wherein the hydrogen bond donor is benzamide and the hydrogen bond acceptor is cobalt chloride hexahydrate.

[0033] In this embodiment, the preparation method of the low-melting ionic liquid is as follows: a hydrogen bond donor and a hydrogen bond acceptor are mixed in a molar ratio of 5:1, and the mixed solution is magnetically stirred in an 80°C water bath environment for 20 minutes until a clear and transparent homogeneous solution is formed to obtain a low-melting ionic liquid.

[0034] Example 4

[0035] This embodiment provides a eutectic ionic liquid and a preparation method thereof. The eutectic ionic liquid is a binary system ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor, wherein the hydrogen bond donor is phenylacetamide and the hydrogen bond acceptor is cobalt chloride hexahydrate.

[0036] In this embodiment, the preparation method of the low-melting ionic liquid is as follows: a hydrogen bond donor and a hydrogen bond acceptor are mixed in a molar ratio of 10:1, and the mixed solution is magnetically stirred in a 40°C water bath environment for 60 minutes until a clear and transparent homogeneous solution is formed to obtain a low-melting ionic liquid.

[0037] Example 5

[0038] This embodiment provides a eutectic ionic liquid and a preparation method thereof. The eutectic ionic liquid is a binary system ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor, wherein the hydrogen bond donor is terephthalamide and the hydrogen bond acceptor is nickel chloride hexahydrate.

[0039] In this embodiment, the preparation method of the low-melting ionic liquid is as follows: a hydrogen bond donor and a hydrogen bond acceptor are mixed in a molar ratio of 10:1, and the mixed solution is magnetically stirred in a 90°C water bath environment for 10 minutes until a clear and transparent homogeneous solution is formed to obtain a low-melting ionic liquid.

[0040] Example 6

[0041] This embodiment provides a eutectic ionic liquid and a preparation method thereof. The eutectic ionic liquid is a ternary system ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor, wherein the hydrogen bond donor is a composition of equimolar amounts of benzamide and phenylacetamide, and the hydrogen bond acceptor is nickel chloride hexahydrate.

[0042] In this embodiment, the preparation method of the low-melting ionic liquid is as follows: a hydrogen bond donor and a hydrogen bond acceptor are mixed in a molar ratio of 2:1, and the mixed solution is magnetically stirred in a water bath environment at 70°C for 30 minutes until a clear and transparent homogeneous solution is formed to obtain a low-melting ionic liquid.

[0043] Example 7

[0044] This embodiment provides a eutectic ionic liquid and a preparation method thereof. The eutectic ionic liquid is a ternary system ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor, wherein the hydrogen bond donor is phenylacetamide, and the hydrogen bond acceptor is a composition of equimolar amounts of nickel chloride hexahydrate and cobalt chloride hexahydrate.

[0045] In this embodiment, the preparation method of the low-melting ionic liquid is as follows: a hydrogen bond donor and a hydrogen bond acceptor are mixed in a molar ratio of 2:1, and the mixed solution is magnetically stirred in a water bath environment at 70°C for 30 minutes until a clear and transparent homogeneous solution is formed to obtain a low-melting ionic liquid.

[0046] Comparative Example 1

[0047] This comparative example provides a binary ionic liquid and a preparation method thereof. Except for replacing the hydrogen bond donor with ethylene glycol, the remaining steps and conditions are the same as those in Example 1, and therefore are not described in detail here.

[0048] Comparative Example 2

[0049] This comparative example provides a binary ionic liquid and a preparation method thereof. Except for replacing the hydrogen bond acceptor with choline chloride, the remaining steps and conditions are the same as those in Example 1, and therefore are not described in detail here.

[0050] Comparative Example 3

[0051] This comparative example provides a ternary ionic liquid and a preparation method thereof. Except that the hydrogen bond acceptor is replaced by a combination of choline chloride and betaine in equimolar amounts, the remaining steps and conditions are the same as those in Example 6 and are therefore not described in detail here.

[0052] Comparative Example 4

[0053] This comparative example provides a ternary ionic liquid and a preparation method thereof. Except that the hydrogen bond donor is replaced by a composition of ethylene glycol and butanediol in equimolar amounts, the remaining steps and conditions are the same as those in Example 7 and are therefore not described in detail here.

[0054] Performance Testing

[0055] (1) 1 cc of each of the ionic liquids obtained in Examples 1-7 and Comparative Examples 1-4 was added to 100 cc of a heavy oil sample. The samples were allowed to stand at 90° C. for 4 days. The viscosity, specific gravity, and asphaltene content of the samples were analyzed. The analytical results are shown in Table 1 below.

[0056] Table 1

[0057]

[0058]

[0059] (2) The ionic liquids obtained in Examples 1-7 and Comparative Examples 1-4 were respectively selected to prepare 2 wt% aqueous ionic liquid solutions as water flooding and oil displacement systems for core displacement experiments, and the recovery factors were calculated (see Table 2 below).

[0060] Table 2

[0061]

[0062]

[0063] It can be seen that the present invention uses an amide compound as a hydrogen bond donor and a metal salt hydrate as a hydrogen bond acceptor. The resulting eutectic ionic liquid can promote slight chemical cracking of asphaltenes in heavy oil, effectively reduce the viscosity of the heavy oil, promote the stripping of the oil film, and thus improve the crude oil recovery rate. Combining the eutectic ionic liquid with water flooding can reduce the oil-water interfacial tension and improve the water flooding effect. At the same time, the eutectic ionic liquid is biodegradable and has a low production cost, which is conducive to large-scale promotion and application.

[0064] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A eutectic ionic liquid, characterized in that The eutectic ionic liquid is a binary or ternary ionic liquid consisting of a hydrogen bond donor and a hydrogen bond acceptor; The hydrogen bond donor is an amide compound, and the hydrogen bond acceptor is a metal salt hydrate.

2. The eutectic ionic liquid according to claim 1, characterized in that The amide compound includes any one of benzamide, phenylacetamide, terephthalamide or caprolactam, or a combination of at least two thereof.

3. The eutectic ionic liquid according to claim 1 or 2, characterized in that The metal salt hydrate includes any one of nickel chloride hexahydrate, cobalt chloride hexahydrate, ferric chloride hexahydrate or manganese chloride tetrahydrate, or a combination of at least two thereof.

4. A method for preparing the eutectic ionic liquid according to any one of claims 1 to 3, characterized in that: The preparation method comprises: mixing a hydrogen bond donor and a hydrogen bond acceptor, stirring and heating the mixture until a clear and transparent homogeneous solution is formed to obtain a eutectic ionic liquid.

5. The preparation method according to claim 4, characterized in that The mixing molar ratio of the hydrogen bond donor and the hydrogen bond acceptor is (1-10):1, more preferably (1-5):

1.

6. The preparation method according to claim 4 or 5, characterized in that The stirring and heating method includes: magnetically stirring the mixed solution in a water bath environment.

7. The preparation method according to any one of claims 4 to 6, characterized in that The stirring and heating temperature is 40-90°C, more preferably 60-80°C; Preferably, the stirring and heating time is 10-60 min, more preferably 20-40 min.

8. The preparation method according to any one of claims 4 to 7, characterized in that The preparation method comprises: mixing a hydrogen bond donor and a hydrogen bond acceptor in a molar ratio of (1-5):1, magnetically stirring the mixed solution in a water bath environment at 60-80°C for 20-40 minutes until a clear and transparent homogeneous solution is formed, thereby obtaining a eutectic ionic liquid.

9. A use of the eutectic ionic liquid according to any one of claims 1 to 3, characterized in that: The aqueous solution of the eutectic ionic liquid is used as a water flooding and oil displacement system.

10. The use according to claim 9, characterized in that The concentration of the eutectic ionic liquid in the water flooding and oil displacement system is 1-10 wt %, more preferably 1-5 wt %.

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