Multi-component complex system nano oil displacement agent, preparation method and application thereof

Abstract

This invention discloses a multi-component compound system of nano-oil displacement agent, its preparation method, and its application. The multi-component compound system of nano-oil displacement agent comprises anionic surfactant and co-surfactant; the anionic surfactant is at least one compound having the general formula shown in formula (I): R1-Indole-O-(PO). n (EO) m CH2COOMa formula (I), where R1 is C1~C 20 The hydrocarbon group; n is any integer from 0 to 20; m is any integer from 0 to 30; and m and n are not both 0; M is an alkali metal or an alkaline earth metal, where a is 1 when M is an alkali metal and 0.5 when M is an alkaline earth metal; the co-surfactant is selected from at least one of zwitterionic surfactants and cationic surfactants. This multi-component compound system of nano-oil displacement agent can form nano-microemulsions with extremely low interfacial tension, strong solubilization ability, and micelle size reaching the nanoscale. It has strong anti-adsorption ability in formations and is suitable for low-permeability reservoirs with harsh conditions.

Description

Technical Field

[0001] This invention relates to the field of oil displacement agent technology, specifically to a multi-component compound system of nano-oil displacement agent, its preparation method, and its application. Background Technology

[0002] Low-permeability reservoirs have small pore throat radii and low permeability, making it difficult for conventional oil displacement agents to work effectively, resulting in problems such as insignificant recovery rate improvement and low oil displacement efficiency.

[0003] Conventional oil displacement methods include mixing nanoparticles with fluids to increase the fluid's wedge-shaped disintegration ability, or using modified nanoparticles to reduce oil-water interfacial tension and improve wettability. However, nanoparticles are prone to aggregation and it is difficult to achieve ultra-low oil-water interfacial tension. Therefore, how to more effectively improve the oil displacement efficiency of low-permeability reservoirs and provide an oil displacement agent suitable for harsh conditions in low-permeability reservoirs is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a multi-component compound system of nano-displacement agent, its preparation method, and its application. This multi-component compound system of nano-displacement agent can form nano-microemulsions, exhibiting extremely low interfacial tension, strong solubilization ability, and nanoscale micelle size. It also demonstrates strong anti-adsorption capacity in formations and is suitable for harsh, low-permeability oil reservoirs.

[0005] One objective of this invention is to provide a multi-component compound system of nano-oil displacement agent, comprising anionic surfactant and co-surfactant; wherein the anionic surfactant is at least one compound having the general formula shown in formula (I):

[0006] R1-Indole-O-(PO) n (EO) m CH2COOMa formula (I),

[0007] Where R1 is C1~C 20 The hydrocarbon group; n is any integer from 0 to 20; m is any integer from 0 to 30; and m and n are not both 0; M is an alkali metal or an alkaline earth metal, when M is an alkali metal, a is 1, and when M is an alkaline earth metal, a is 0.5; Indole is an indole group, and -R1 and -O attached to the indole group are independently at any substitution position of the indole group; PO is -CH2CH2CH2O-; EO is -CH2CH2O-;

[0008] The co-surfactant is selected from at least one of zwitterionic surfactants and cationic surfactants.

[0009] In a preferred embodiment of the present invention,

[0010] The anionic surfactant has the following structure:

[0011]

[0012] Where R1 is C1~C 20 The hydrocarbon group; n is any integer from 0 to 20; m is any integer from 0 to 30; and m and n are not both 0; M is an alkali metal or an alkaline earth metal. When M is an alkali metal, a is 1, and when M is an alkaline earth metal, a is 0.5.

[0013] In a preferred embodiment of the present invention,

[0014] R1 is C1~C 20 Alkyl groups, preferably C6-C6. 18 Alkyl groups, more preferably C6-C6. 12 Alkyl groups; and / or,

[0015] The n is any integer from 1 to 15, preferably any integer from 4 to 10, and more preferably any integer from 3 to 6; and / or,

[0016] The m is any integer from 0 to 20, preferably any integer from 2 to 15, more preferably any integer from 2 to 12, and most preferably any integer from 4 to 10.

[0017] In a preferred embodiment of the present invention,

[0018] m+n is any integer from 4 to 30, preferably any integer from 4 to 20, and more preferably any integer from 8 to 18.

[0019] The anionic surfactant of formula (I) described above can be a commercially available product from the prior art, or it can be prepared by a reaction method of the prior art, the preferred preparation method of which includes:

[0020] When either m or n is 0:

[0021] R1-Indole-OH, ethylene oxide, or propylene oxide are reacted in the presence of a base catalyst (reaction temperature 50–250 °C, reaction time 1–20 h, reaction pressure less than 0.4 MPa) to obtain R1-Indole-O-(EO). m H or R1-Indole-O-(PO) n H, then add an equimolar (or slightly excess) amount of NaOH for alkalization, and then add an equimolar (or slightly excess) amount of chloroacetate for carboxymethylation reaction (at ambient pressure, reaction temperature 40-150℃, reaction time 4-8h) to obtain the anionic surfactant described in formula (I).

[0022] When both m and n are not 0:

[0023] R1-Indole-OH and propylene oxide were reacted in the presence of a base catalyst (reaction temperature 50–250 °C, reaction time 1–20 h, reaction pressure less than 0.4 MPa) to obtain R1-Indole-O-(PO). n H, ethylene oxide is added to continue the alkylation reaction (reaction temperature 50-250℃, reaction time 1-20h, reaction pressure less than 0.4MPa) to obtain R1-Indole-O-(PO). n (EO) m H, then add an equimolar (or slightly excess) amount of NaOH for alkalization, and then add an equimolar (or slightly excess) amount of chloroacetate for carboxymethylation reaction (at ambient pressure, reaction temperature 40-150℃, reaction time 4-8h) to obtain the anionic surfactant described in formula (I).

[0024] The alkaline catalyst described above is at least one of NaOH, KOH, LiOH, CsOH, and RbOH; and / or, the chloroacetate is at least one of an alkali metal chloroacetate and an alkaline earth metal chloroacetate.

[0025] The molar ratio of R1-Indole-OH, ethylene oxide, propylene oxide and the base catalyst mentioned above is 1:0~30:0~20:0.1~1;

[0026] In the preparation method described above, the amounts of propylene oxide and ethylene oxide can be determined according to the structure of the target anionic surfactant. Specifically, propylene oxide is added in an amount that is 50-150% excess relative to the stoichiometric ratio, for example, 90-110%, and / or ethylene oxide is added in an amount that is 0.5-30% excess relative to the stoichiometric ratio, preferably 1-20%, more preferably 1-15%.

[0027] The preparation method described above allows for separation and purification using any known method in the art after the carboxymethylation reaction, thereby obtaining various product forms of the anionic surfactant described in this invention. For example, acid can be added to the reaction product after the carboxymethylation reaction to adjust the pH to 1-3, the organic phase can be separated, and after concentrating the organic phase, a base can be added to obtain the anionic surfactant shown in Formula I. Alternatively, after concentrating the organic phase, the acidic product form of the anionic surfactant shown in Formula I can be directly obtained.

[0028] In the preparation method described above, R1-Indole-OH can be a commercially available product from the prior art, or it can be prepared by any known method in the art. The preferred preparation method includes: heating hydroxyindole and R1-X (X represents halogen) under reflux in the presence of organic solvent and NaOH, followed by extraction and rapid column chromatography to obtain the product.

[0029] In a preferred embodiment of the present invention,

[0030] The zwitterionic surfactant is at least one of the compounds of the general formula shown in formula (II):

[0031] R2N(CH3)2CH2COO (Formula II)

[0032] Where R2 is C1 to C 20 Hydrocarbon group.

[0033] In a preferred embodiment of the present invention,

[0034] The zwitterionic surfactant is a betaine-type zwitterionic surfactant.

[0035] In a preferred embodiment of the present invention,

[0036] R2 is C1 to C 20 Alkyl groups, preferably C6-C6. 18 Alkyl groups, more preferably C14 groups. 10 ~C 14 Alkyl groups.

[0037] In a preferred embodiment of the present invention,

[0038] The cationic surfactant is at least one of the compounds of the general formula shown in formula (III):

[0039] R3NMe3X (III),

[0040] Where R3 is C1 to C 20 The hydrocarbon group; X is a halogen.

[0041] In a preferred embodiment of the present invention,

[0042] R3 is C1 to C 20 Alkyl groups, preferably C6-C6. 18 Alkyl groups, more preferably C8 to C96. 18 Alkyl groups, most preferably C 14 ~C 18 Alkyl groups.

[0043] In a preferred embodiment of the present invention,

[0044] The co-surfactant includes amphoteric surfactants and cationic surfactants; preferably, the ratio of the amount of amphoteric surfactant to cationic surfactant is (1-99):(99-1), more preferably (45-55):(55-45), and even more preferably 1:1.

[0045] In a preferred embodiment of the present invention,

[0046] The content of anionic surfactant in the multi-component compound system nano oil displacement agent is 99.9-50.1 wt%, preferably 80-55 wt%, more preferably 70-60 wt%, and most preferably 65-60 wt%.

[0047] In the above technical solutions, when the multi-component compound system nano-oil displacement agent is a mixture of the above-mentioned anionic surfactant, amphoteric surfactant and cationic surfactant, the proportion of anionic surfactant is 99.9-50.1 wt%, preferably 80-55 wt%, more preferably 70-60 wt%, and most preferably 65-60 wt%, the proportion of amphoteric surfactant is 1.0-25 wt%, preferably 1.0-20 wt%, the proportion of cationic surfactant is 25-49.9 wt%, preferably 30-49.9 wt%, and the total proportion of cationic and amphoteric surfactants does not exceed 50 wt%.

[0048] A second objective of this invention is to provide a method for preparing a multi-component compound system nano-oil displacement agent, which is one of the objectives of this invention. The method includes mixing components including the anionic surfactant and the co-surfactant to obtain the multi-component compound system nano-oil displacement agent.

[0049] The third objective of this invention is to provide a multi-component compound system nano-displacement agent for oil recovery in low-permeability reservoirs, which is either a multi-component compound system nano-displacement agent obtained by the preparation method of the second objective of this invention.

[0050] This invention has the following advantages:

[0051] (1) The multi-component compound surfactant of the present invention can still form 10 under alkali-free and high-temperature conditions. -3 With an ultra-low interfacial tension of mN / m, it has good solubilization effect, strong anti-adsorption capacity, and excellent oil displacement effect, which can improve crude oil recovery rate.

[0052] (2) The surfactant of the present invention can be used in tertiary oil recovery. No alkali needs to be added during use (it does not contain alkali), which can greatly reduce the huge damage of alkali to the formation and oil well, and meets the environmental protection requirements. Detailed Implementation

[0053] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0054] The cationic surfactant used in the embodiments of the present invention is hexadecyltrimethylammonium chloride (commercially available), and the amphoteric surfactant is lauryl betaine (commercially available).

[0055] The anionic surfactant used in the embodiments of this invention is C9H. 19 -Indole-O-(EO)7CH2COONa (The specific structural formula is: ), of which C9H 19 It is a straight-chain alkyl group, and its preparation process is as follows:

[0056] 1) Add 400 ml of dichloromethane, 133.2 g (1 mol) of 5-hydroxyindole, 170.8 g (1.05 mol) of 1-chlorononane and 60 g of NaOH to a reactor equipped with a reflux device. Heat under reflux at 70 °C for 8 hours. After cooling, extract with ethyl acetate. Remove the solvent by rotary evaporation after extraction. Obtain the final product using rapid column chromatography. 104g, yield 40%;

[0057] 2) Add 25.9 g (0.1 mol) of the above-mentioned material to a 200 mL pressure reactor equipped with a stirrer. Add 6g KOH, heat to 85℃, turn on the vacuum system, and dehydrate under high vacuum for 1 hour. Then, purge with nitrogen four times. Subsequently, adjust the reaction temperature to 140℃, slowly introduce 34.7g (0.79mol) ethylene oxide, and control the gauge pressure to be less than 0.4MPa. After the reaction (approximately 6 hours) is complete, cool to 90℃, remove low-boiling-point substances under vacuum, cool, neutralize, and remove water to obtain C9-Indole-(EO)7H (specific structural formula: 50g, yield 88%.

[0058] 3) Add 50g of C9-Indole-(EO)7H to a 1L reactor, dissolve it in 200mL of benzene, then add 4g (0.1 mol) of NaOH. After reacting at 80℃ for 4 hours, add 12g (approximately 0.1 mol) of sodium chloroacetate, maintain the reaction temperature, and react for 6 hours. Then acidify to pH 2 of the aqueous phase, wash with water, extract the organic phase, and dry by rotary evaporation to obtain C9H. 19 -Indole-O-(EO)7CH2COOH, approximately 52g, yield 94%. Finally, the resulting organic acid (C9H...) was... 19Adding an equimolar amount of NaOH to (-Indole-O-(EO)7CH2COOH) yields...

[0059] Two components:

[0060] Example 1: Interfacial Tension Test

[0061] The interfacial tension of cationic and anionic surfactant formulations with different compounding ratios was tested. A 0.1% total concentration solution was prepared using produced water from the Shengli Oilfield, and Shengli Oilfield crude oil was used as the oil phase. The interfacial tension experiment was conducted at 100℃. Experimental method: The 0.1% surfactant solution was used as the aqueous phase, and Shengli Oilfield crude oil was used as the oil phase. The oil-water interfacial tension (IFT) was measured using a Kruss SDT rotating drop interfacial tensiometer at 100℃ and a rotation speed of 4500 rpm / min.

[0062] Anionic:Cationic surfactant ratio Interfacial tension (mN / m) 9：1 0.2 8：2 0.06 7：3 0.04 65：35 <![CDATA[3*10 -3 ]]> 6：4 <![CDATA[2.4*10 -3 ]]> 55：45 <![CDATA[3.5*10 -3 ]]>

[0063] Comparative Example 1: Interfacial Tension Test

[0064] Except for the absence of cationic surfactants, the experimental procedures were the same as in Example 1.

[0065] Anionic:Cationic surfactant ratio Interfacial tension (mN / m) 10:0 0.8

[0066] Example 2: Phase Behavior and Solubilization Ability Test

[0067] The solubilizing ability of cationic and anionic surfactant formulations with different compounding ratios was tested. A 0.1% total concentration solution was prepared using produced water from the Shengli Oilfield. Shengli Oilfield crude oil was used as the oil phase, with an oil-to-water ratio of 1:1. Phase behavior and solubilizing ability experiments were conducted at 100℃. Experimental method: A glass capillary phase equilibrium experiment was used. The self-made anionic surfactant and other co-surfactants were dissolved in the corresponding produced water to prepare a surfactant mass fraction of 0.1%. These were then compounded according to the specified ratio and mixed thoroughly. 1 mL of the compounded solution was added to a pipette with a sealed bottom, followed by 1 mL of crude oil. The pipette was then sealed and placed in a Corning Gorilla Glass test tube, and silicone oil was added. The test tube was sealed and placed in a constant-temperature metal bath, heated to 100℃, and the solution was shaken to mix thoroughly. After two days of mixing, the solution remained in the constant-temperature metal bath, and the phase state experiment was photographed and recorded.

[0068]

[0069] Comparative Example 2: Phase Behavior and Solubilization Capacity Test

[0070] Except for the absence of cationic surfactants, the experimental procedures were the same as in Example 2.

[0071]

[0072] Example 3 Particle size test

[0073] The particle size of cationic and anionic surfactant formulations with different compounding ratios was tested. A 0.1% total concentration solution was prepared using produced water from the Shengli Oilfield, and the temperature was set at 80℃. Experimental procedure: A 0.1% concentration solution was prepared using produced water, placed in a Marvel particle size analyzer, heated to the required temperature, and then tested.

[0074]

[0075] Comparative Example 3 Particle Size Test

[0076] Except for the absence of cationic surfactants, the experimental procedures were the same as in Example 3.

[0077]

[0078] Example 4: Oil-washing ability test

[0079] The oil washing capacity of cationic and anionic surfactant formulations with different compounding ratios was tested. A 0.1% total concentration solution was prepared using produced water from the Shengli Oilfield at 100℃. Oil sands were prepared according to standard Q / SH10202191-2013, and then tested according to this standard. The oil washing rate was then calculated.

[0080]

[0081]

[0082] Comparative Example 4: Oil-washing ability test

[0083] Except for the absence of cationic surfactants, the experimental procedures are the same as in Example 4.

[0084]

[0085] Example 5 Adsorption Capacity Test

[0086] The adsorption capacity of cationic and anionic surfactant formulations with different compounding ratios was tested. A 0.1% total concentration solution was prepared using produced water from the Shengli Oilfield, and quartz sand was added for adsorption at 80℃. Experimental method: Prepare the appropriate concentration of compound surfactant solution using 60-80 mesh quartz sand at a mass ratio of 1:5. After adding the liquid, shake for 24 hours, then centrifuge and separate the layers. The supernatant was used to test the concentration of the remaining surfactant, and the adsorption loss was calculated.

[0087]

[0088] Comparative Example 5 Adsorption Capacity Test

[0089] Except for the absence of cationic surfactants, the experimental procedures are the same as in Example 5.

[0090]

[0091] Multi-component:

[0092] Example 6: Interfacial Tension Test

[0093] The interfacial tension capacity of multi-component surfactant formulations with different compounding ratios was tested. A solution with a total concentration of 0.1% was prepared using produced water from the Shengli Oilfield. Interfacial tension experiments were conducted using Shengli Oilfield crude oil as the oil phase at a temperature of 100℃. The experimental method was the same as in Example 1.

[0094]

[0095] Example 7: Solubilization Capacity Test

[0096] The interfacial tension of multi-component surfactant formulations with different compounding ratios was tested. A solution with a total concentration of 0.1% was prepared using produced water from the Shengli Oilfield. Shengli Oilfield crude oil was used as the oil phase, with an oil-water ratio of 1:1. Phase behavior and solubilization capacity experiments were conducted at 100℃. The experimental method was the same as in Example 2.

[0097]

[0098]

[0099] Example 8 Particle size test

[0100] The particle size of the multi-component surfactant formulations with different compounding ratios was tested. A solution with a total concentration of 0.1% was prepared using produced water from the Shengli Oilfield and the temperature was 80℃. The experimental procedure was the same as in Example 3.

[0101]

[0102] Example 9: Oil-washing ability test

[0103] The oil-washing ability of multi-component surfactant formulations with different compounding ratios was tested. A solution with a total concentration of 0.1% was prepared using produced water from the Shengli Oilfield and the temperature was 100℃. The test method was the same as in Example 4.

[0104]

[0105]

[0106] Example 10 Adsorption Capacity Test

[0107] The adsorption capacity of multi-component surfactant formulations with different compounding ratios was tested. A solution with a total concentration of 0.1% was prepared using produced water from the Shengli Oilfield, and quartz sand was added for adsorption at a temperature of 80°C. The experimental method was the same as in Example 5.

[0108] Anion:Zwitterion:Cation Ratio Adsorption loss (mg / g) 90：5：5 0.9 80：10：10 0.6 70：15：15 0.2 65：17.5：17.5 0.1 60：20：20 0.2 55：22.5：22.5 0.3

[0109] As can be seen from the examples and comparative examples, the multi-component compound system of the present invention exhibits lower CMC, lower adsorption capacity, stronger interfacial activity (low interfacial tension), and stronger wettability improvement ability due to the synergistic effect between the surfactants. Because it forms a nanoemulsion, the micelle radius is small, allowing it to enter regions with smaller pores, improving sweep efficiency, and making it suitable for oil displacement in low-permeability reservoirs to enhance oil recovery.

Claims

1. A multi-component compound system of nano-oil displacement agent, comprising anionic surfactant and co-surfactant; wherein the anionic surfactant is at least one compound having the general formula shown in formula (I): R1-Indole-O-(PO) n (EO) m CH2COOM a Formula (I), in, R1 is C6~C 18 Alkyl group; m+n is any integer from 7 to 18; M is an alkali metal or an alkaline earth metal, where a is 1 when M is an alkali metal and 0.5 when M is an alkaline earth metal; The co-surfactant is selected from at least one of zwitterionic surfactants and cationic surfactants; The zwitterionic surfactant is at least one of the compounds of the general formula shown in formula (II): R2N(CH3)2CH2COO formula (II). Where R2 is C1~C 20 hydrocarbon group; The cationic surfactant is at least one of the compounds of the general formula shown in formula (III): R3NMe3X (III) Where R3 is C1~C 20 The hydrocarbon group; X represents a halogen; Me represents a methyl group; The content of anionic surfactant in the multi-component compound system of nano-oil displacement agent is 99.9~50.1wt%.

2. The multi-component compound system nano-oil displacement agent as described in claim 1, characterized in that: The anionic surfactant has the following structure: Where R1 is C6~C 18 Alkyl group; m+n is any integer from 7 to 18; M is an alkali metal or an alkaline earth metal, where a is 1 when M is an alkali metal and 0.5 when M is an alkaline earth metal.

3. The multi-component compound system nano-oil displacement agent according to any one of claims 1-2, characterized in that: The n is any integer from 1 to 15.

4. The multi-component compound system nano-oil displacement agent as described in claim 3, characterized in that: R1 is C6~C 12 Alkyl groups; and / or, The n is any integer from 4 to 10; and / or, The value of m is any integer from 2 to 15.

5. The multi-component compound system nano-oil displacement agent as described in claim 4, characterized in that: The n is any integer from 3 to 6; and / or, The value of m is any integer from 2 to 12.

6. The multi-component compound system nano-oil displacement agent as described in claim 5, characterized in that: The value of m is any integer from 4 to 10.

7. The multi-component compound system nano-oil displacement agent as described in claim 1, characterized in that: m+n is any integer from 8 to 18.

8. The multi-component compound system nano-oil displacement agent as described in claim 1, characterized in that: R2 is C1~C 20 Alkyl groups.

9. The multi-component compound system nano-oil displacement agent as described in claim 8, characterized in that: R2 is C6~C 18 Alkyl groups.

10. The multi-component compound system nano-oil displacement agent as described in claim 9, characterized in that: R2 is C 10 ~C 14 Alkyl groups.

11. The multi-component compound system nano-oil displacement agent as described in claim 1, characterized in that: R3 is C1~C 20 Alkyl groups.

12. The multi-component compound system nano-oil displacement agent as described in claim 11, characterized in that: R3 is C6~C 18 Alkyl groups.

13. The multi-component compound system nano-oil displacement agent as described in claim 12, characterized in that: R3 is C8~C 18 Alkyl groups.

14. The multi-component compound system nano-oil displacement agent as described in claim 13, characterized in that: R3 is C 14 ~C 18 Alkyl groups.

15. The multi-component compound system nano-oil displacement agent as described in claim 1, characterized in that: The co-surfactants include zwitterionic surfactants and cationic surfactants.

16. The multi-component compound system nano-oil displacement agent as described in claim 15, characterized in that: The ratio of the amount of zwitterionic surfactant to cationic surfactant is (1~99):(99~1).

17. The multi-component compound system nano-oil displacement agent as described in claim 16, characterized in that: The ratio of the amount of zwitterionic surfactant to cationic surfactant is (45~55):(55~45).

18. The multi-component compound system nano-oil displacement agent as described in claim 1, characterized in that: The content of anionic surfactant in the multi-component compound system of nano-oil displacement agent is 80~55wt%.

19. The multi-component compound system nano-oil displacement agent as described in claim 18, characterized in that: The content of anionic surfactant in the multi-component compound system of nano-oil displacement agent is 70~60wt%.

20. A device as claimed in claim 1 The preparation method of the multi-component compound system nano-oil displacement agent according to any one of 19 includes mixing the components including the anionic surfactant and the co-surfactant to obtain the multi-component compound system nano-oil displacement agent.

21. The application of a multi-component compound system nano-displacement agent as described in any one of claims 1 to 19, or a multi-component compound system nano-displacement agent obtained by the preparation method described in claim 20, in oil production in low-permeability reservoirs.

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