Surfactant composition as well as preparation method and application thereof

Abstract

The invention relates to the field of colloid and interface chemistry, in particular to a surfactant composition for composite oil displacement, which comprises a surfactant A, a surfactant B, a surfactant aid and water, wherein the surfactant A is a gemini surfactant, and the surfactant B is a polyoxyethylene ether monomer surfactant. Extremely low oil-water interfacial tension exists between the surfactant composition and an oil phase, so that crude oil drops can be automatically stretched into a cylindrical state in a surfactant composition solution. The oil recovery rate can be improved and the oil extraction energy consumption can be reduced when the oil extraction agent is applied to a chemical combination flooding technology.

Description

Technical Field

[0001] The invention belongs to the field of chemical oil recovery and relates to a surfactant composition and a preparation method and application thereof. Background Art

[0002] Chemical composite flooding is an important technology for improving oil recovery in my country. The composite flooding system consists of a polymer (partially hydrolyzed polyacrylamide) with a concentration of 1500-2500 mg / L and a surfactant with a concentration of 0.2%-0.6%. Its technical characteristics are that the polymer provides a higher system viscosity, and the surfactant can reduce the oil-water interfacial tension between the flooding system and crude oil, thereby achieving the dual effects of expanding the sweep and improving the oil recovery efficiency, and achieving the purpose of significantly improving oil recovery. Under normal circumstances, the surfactant in the composite flooding system can reduce the oil-water interfacial tension to an ultra-low level, and the interfacial tension is less than 0.01mN / m, which is the so-called ultra-low interfacial tension.

[0003] At present, the spinning drop method is used to measure the oil-water interfacial tension of surfactants used for oil displacement. During the measurement, the surfactant solution is injected into a glass capillary tube (measuring tube) with an inner diameter of 2 mm. The measuring tube is kept horizontal and an oil drop is added to the measuring tube through a syringe with a long needle. Under the action of the oil-water interfacial tension and the density difference, the oil drop will remain in the upper part of the measuring tube. Figure 1 Start the measuring instrument and rotate the measuring tube at high speed (5000 rpm). Under the action of the oil-water density difference, oil-water interfacial tension and high-speed centrifugal force, the oil droplet moves to the axial center of the measuring tube and gradually stretches along the axial direction into a slender cylindrical state, as shown in Figure 1. Figure 2 As shown. When the length and diameter of the slender oil column reach a stable state, the oil-water interfacial tension is calculated based on the diameter of the slender cylinder. The ultra-low interfacial tension feature of the surfactant in the existing composite oil recovery system is that the oil droplets are stretched into a slender cylindrical state under the centrifugal force generated by high-speed rotation, that is, the surfactant can only stretch the oil droplets into a slender cylindrical state under the action of high-speed centrifugal force. Summary of the invention

[0004] The purpose of the present invention is to solve the problem in the prior art that surfactants must be subjected to high-speed centrifugal force to stretch oil droplets therein into an elongated cylindrical state, and to provide a surfactant composition for composite oil recovery and a preparation method and application thereof, thereby reducing oil recovery energy consumption while improving oil recovery rate.

[0005] The inventor of the present invention has found in research that a composition obtained by mixing some surfactants, additives and water in a certain proportion can greatly reduce the oil-water interfacial tension. Without the need for external high-speed centrifugal force, the surfactant composition can automatically stretch the oil droplets in the measuring tube of the spinning drop interfacial tension meter into a slender cylindrical state, which can be used in chemical composite flooding technology to improve oil recovery and reduce oil production energy consumption. Based on the above findings, the present invention is proposed.

[0006] The first aspect of the present invention provides a surfactant composition for composite oil displacement, wherein the composition comprises surfactant A, surfactant B, surfactant adjuvant and water;

[0007] Wherein, the surfactant A is a gemini surfactant;

[0008] Wherein, the surfactant B is a polyvinyl ether surfactant.

[0009] A second aspect of the present invention provides a method for preparing a surfactant composition, wherein the method comprises:

[0010] (1) dissolving surfactant B into aqueous solution B;

[0011] (2) mixing a surfactant adjuvant and the aqueous solution B to obtain an aqueous solution A;

[0012] (3) mixing the surfactant A and the aqueous solution A to obtain a mixture;

[0013] (4) heating and stirring the mixture until it completely becomes a transparent and uniform liquid;

[0014] Wherein, the surfactant A is a gemini surfactant, and the surfactant B is a polyoxyethylene ether monomer surfactant.

[0015] The third aspect of the present invention provides the use of the surfactant composition of the present invention in chemical composite flooding technology.

[0016] Through the above technical scheme, the surfactant composition provided by the present invention has ultra-low oil-water interfacial tension. Without the need for external high-speed centrifugal force, the surfactant composition can automatically stretch oil droplets into a slender cylindrical state, thereby improving the oil recovery rate in chemical composite flooding technology and reducing oil production energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a photograph of the phenomenon that crude oil droplets in the prior art field cannot automatically stretch and spread in a surfactant solution and appear in the shape of small droplets;

[0018] Figure 2This is a photograph of the phenomenon in which a surfactant solution containing crude oil droplets is stretched and spread under high-speed rotation (5000 rpm) in the field of the prior art, and the cylindrical shape is formed;

[0019] Figure 3 This is a photograph showing the phenomenon that a crude oil droplet automatically stretches and spreads in the aqueous solution of the surfactant composition prepared in Example 1 of the present invention to form a cylindrical shape;

[0020] Figure 4 This is a photograph showing the phenomenon that a crude oil droplet automatically stretches and spreads in the aqueous solution of the surfactant composition prepared in Example 2 of the present invention to form a cylindrical shape;

[0021] Figure 5 This is a photograph showing the phenomenon that a crude oil droplet automatically stretches and spreads in the aqueous solution of the surfactant composition prepared in Example 3 of the present invention to form a cylindrical shape;

[0022] Figure 6 This is a photograph showing the phenomenon that crude oil droplets cannot automatically stretch and spread in the aqueous solution of the surfactant composition prepared in Comparative Example 1 of the present invention, and appear in the form of small droplets.

[0023] Figure 7 This is a photograph showing the phenomenon that a crude oil droplet cannot automatically stretch and spread in the aqueous solution of the surfactant composition prepared in Comparative Example 2 of the present invention, and takes on an elliptical shape.

[0024] Description of Reference Numerals

[0025] 1: crude oil drop; 2: surfactant composition aqueous solution; 3: surfactant composition aqueous solution liquid surface. DETAILED DESCRIPTION

[0026] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0027] The first aspect of the present invention provides a surfactant composition for composite oil displacement, wherein the composition comprises surfactant A, surfactant B, surfactant adjuvant and water;

[0028] Wherein, the surfactant A is a gemini surfactant;

[0029] Wherein, the surfactant B is a polyvinyl ether surfactant.

[0030] In some preferred embodiments of the present invention, preferably, the type of the Gemini surfactant includes at least one of anionic, cationic, nonionic and zwitterionic, preferably a nonionic surfactant. For example, the Gemini surfactant is the CO-EM / DWS series low tension surfactant produced by Dalian Davis Chemical Co., Ltd.

[0031] In some preferred embodiments of the present invention, the CO-EM / DWS series low tension surfactant has a low surface tension (less than 24 mN / m at 45°C, by hanging plate method), a CMC of about 0.06%, a pH of 6-8, and a milky white viscous liquid appearance.

[0032] Preferably, the polyoxyethylene ether surfactant is a castor oil polyoxyethylene ether series surfactant.

[0033] More preferably, the castor oil polyoxyethylene ether series surfactant is at least one of EL-40, HEL-40, EL-60, EL-80 and EL-90.

[0034] More preferably, the castor oil polyoxyethylene ether series surfactant is EL-80.

[0035] In some preferred embodiments of the present invention, preferably, the mass ratio of the surfactant A to the surfactant B is 10: 1-5: 1. Within this mass ratio range, the composition provided by the present invention can achieve the automatic stretching of oil droplets into slender cylindrical shapes.

[0036] In some preferred embodiments of the present invention, preferably, the surfactant adjuvant is selected from ethylene glycol butyl ether and / or diethylene glycol butyl ether, which can bring better solubility to the composition and realize automatic stretching and deformation of the oil droplets.

[0037] In some preferred embodiments of the present invention, preferably, in the composition, the total mass concentration of the surfactant A, the surfactant B and the surfactant adjuvant is 30-40%, preferably 25-40%.

[0038] In some preferred embodiments of the present invention, preferably, the total mass concentration of the surfactant A and the surfactant B is 20-30%.

[0039] In some preferred embodiments of the present invention, preferably, the mass concentration of the surfactant adjuvant is 5-15%.

[0040] In some preferred embodiments of the present invention, preferably, the added amount of the surfactant adjuvant is 20-40% of the total mass of the surfactant A and the surfactant B, preferably 15-40%.

[0041] In the present invention, the content of the above-mentioned components in the composition can ensure that the aqueous solution of the surfactant composition and the oil phase have extremely low oil-water interfacial tension, and the technical effect of oil droplets automatically stretching into slender cylindrical shapes in the surfactant solution is obtained. When it is not within the above-mentioned range, the oil droplets cannot automatically stretch into slender cylindrical shapes in the surfactant solution, but are in the shape of elliptical oil droplets.

[0042] In some preferred embodiments of the present invention, the surfactant composition can reduce the oil-water interface to an ultra-low level. Preferably, the oil-water interfacial tension of the surfactant composition is less than 0.005 mN / m.

[0043] A second aspect of the present invention provides a method for preparing a surfactant composition, the method comprising:

[0044] (1) dissolving surfactant B into aqueous solution B;

[0045] (2) mixing a surfactant adjuvant and the aqueous solution B to obtain an aqueous solution A;

[0046] (3) mixing the surfactant A and the aqueous solution A to obtain a mixture;

[0047] (4) heating and stirring the mixture until it completely becomes a transparent and uniform liquid;

[0048] Wherein, the surfactant A is a gemini surfactant, and the surfactant B is a polyoxyethylene ether monomer surfactant.

[0049] Wherein, in the mixture in step (3), the mass concentration of the surfactant B is 1-10%, preferably 2-5%.

[0050] Wherein, in the mixture in step (3), the mass concentration of the surfactant A is 10-29% and the mass concentration of the surfactant B is 20-25%.

[0051] Wherein, in the mixture in step (3), the mass concentration of the surfactant adjuvant is 5-15%, preferably 5-8%.

[0052] In step (4), the mixture is heated to 30-60°C, preferably to 40°C.

[0053] In the present invention, preferably, the stirring speed is 200-400 rpm.

[0054] The third aspect of the present invention provides the use of the surfactant composition of the present invention in chemical composite flooding technology.

[0055] The present invention will be described in detail below through examples.

[0056] The test method for the oil-water interface performance of the surfactant composition is as follows.

[0057] (1) The surfactant composition is diluted into solutions of different concentrations (greater than 0.1%), and the aqueous solutions of the surfactant composition are loaded into the measuring tube of a spinning drop interfacial tension meter.

[0058] (2) Add a drop of crude oil to the aqueous solution of the surfactant composition in the measuring tube.

[0059] (3) The measuring tube of step (2) is then placed in a constant temperature instrument, and the automatic stretching and spreading phenomenon of the oil droplets in the aqueous solution of the surfactant composition is observed on a computer display screen.

[0060] Gemini surfactant is a low tension surfactant (CO-EM / DWS) produced by Dalian Davis Chemical Co., Ltd.

[0061] Example 1

[0062] Table 1

[0063] Components Gemini surfactants EL-80 Diethylene glycol butyl ether Mass concentration / % 20 3 6

[0064] (1) 3 g of EL-80 was added to 51 g of water to dissolve into an aqueous solution, and then 6 g of an auxiliary agent, diethylene glycol butyl ether, was added thereto, and finally 40 g of a Gemini surfactant with an effective content of 50% was added to prepare a mixture; the mixture was heated to 40° C. and slowly stirred (250 rpm) until the mixture was completely dissolved into a transparent and uniform liquid, to obtain 100 g of a surfactant composition; the mass concentrations of the components in the obtained surfactant composition are shown in Table 1;

[0065] (2) diluting the surfactant composition into a solution with a mass concentration of 0.2 wt %, and loading the solution into a measuring tube of a spinning drop interfacial tension meter;

[0066] (3) A drop of crude oil is added to the measuring tube described in step (2), and the tube is placed in a constant temperature instrument. Under the condition of a rotation speed of 0 rpm, the phenomenon of the oil drop automatically stretching and spreading in the aqueous solution of the surfactant composition to become a slender cylindrical state is observed on the computer display screen.

[0067] Step (3) The oil droplets in the aqueous solution of the surfactant composition are stretched and spread automatically to become elongated cylindrical states. Figure 3 shown.

[0068] The interfacial tension between the surfactant composition solution with a concentration of 0.2% and crude oil is 0.00032 mN / m.

[0069] Example 2

[0070] Table 2

[0071] Components Gemini surfactants EL-80 Diethylene glycol butyl ether Mass concentration / % 20 2 8

[0072] The surfactant composition aqueous solution was prepared according to the method of Example 1, except that in step (1), the mass concentrations of the components in the surfactant composition were as shown in Table 2; in step (2), the surfactant composition was diluted to a solution with a concentration of 0.3 wt%, and the oil-water interfacial tension of the surfactant solution was 0.00014 mN / m. The phenomenon that the obtained oil droplets in the surfactant composition aqueous solution automatically stretched and spread to become a slender cylindrical state is shown in FIG. Figure 4 shown.

[0073] Example 3

[0074] Table 3

[0075] Components Gemini surfactants EL-80 Diethylene glycol butyl ether Mass concentration / % 25 3 5

[0076] The surfactant composition aqueous solution was prepared according to the method of Example 1, except that in step (1), the mass concentrations of the components in the surfactant composition were as shown in Table 3. The phenomenon that the obtained oil droplets in the surfactant composition aqueous solution automatically stretched and spread to become elongated cylindrical states is shown in Figure 5 shown.

[0077] Comparative Example 1

[0078] Table 4

[0079] Components Gemini surfactants EL-80 Diethylene glycol butyl ether Mass concentration / % 20 0 0

[0080] (1) Directly use only the Gemini surfactant (mass concentration is shown in Table 4) and dilute it into a solution with a concentration of 0.2 wt%, and put the solution into the measuring tube of the spinning drop interfacial tension meter;

[0081] (2) A drop of crude oil is added to the measuring tube described in step (1), and the tube is placed in a constant temperature instrument. Under the condition of a rotation speed of 0 rpm, it is observed on the computer screen that the oil droplets in the surfactant aqueous solution cannot automatically stretch and spread, and appear in the form of small droplets.

[0082] (3) The oil droplets in the aqueous solution of the surfactant composition cannot automatically stretch and spread, and are in the form of small droplets. Figure 6 shown.

[0083] Comparative Example 2

[0084] Table 5

[0085] Components Sodium dodecylbenzenesulfonate EL-80 Diethylene glycol butyl ether Mass concentration / % 20 3 6

[0086] (1) diluting the surfactant composition in Table 5 into a solution with a concentration of 0.3 wt%, and placing the solution into a measuring tube of a spinning drop interfacial tension meter;

[0087] (2) A drop of crude oil was added to the measuring tube described in step (1), and the tube was placed in a constant temperature instrument. Under the condition of a rotation speed of 0 rpm, the phenomenon that the oil droplet in the aqueous solution of the surfactant composition could not automatically stretch and spread, and was elliptical, was observed on the computer display screen ( Figure 7 ).

[0088] Combination Figure 3-7 The results show that by comparing Examples 1-3 with Comparative Examples 1 and 2, when the type and mass of crude oil droplets added are the same, the surfactant composition solutions prepared in Examples 1-3 have extremely low oil-water interfacial tension with the oil phase, which can make the oil droplets automatically stretch and spread therein to become a slender cylindrical state. Applying it to chemical composite flooding technology can improve oil recovery and reduce oil production energy consumption.

[0089] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A surfactant composition for composite oil displacement, wherein: The composition comprises surfactant A, surfactant B, surfactant adjuvant and water; Wherein, the surfactant A is a gemini surfactant, and the surfactant B is a polyoxyethylene ether monomer surfactant.

2. The composition according to claim 1, wherein The type of the gemini surfactant includes at least one of anionic, cationic, nonionic and zwitterionic, preferably a nonionic surfactant.

3. The composition according to claim 1 or 2, wherein The polyoxyethylene ether monomer surfactant is a castor oil polyoxyethylene ether series surfactant; preferably at least one of EL-40, HEL-40, EL-60, EL-80, and EL-90; ​​preferably EL-80.

4. The composition according to any one of claims 1 to 3, wherein The mass ratio of the surfactant A to the surfactant B is 10:1-5:

1.

5. The composition according to any one of claims 1 to 4, wherein The surfactant adjuvant is selected from ethylene glycol butyl ether and / or diethylene glycol butyl ether.

6. The composition according to any one of claims 1 to 5, wherein In the composition, the total mass concentration of the surfactant A, the surfactant B and the surfactant adjuvant is 30-40%; Wherein, the total mass concentration of the surfactant A and the surfactant B is 20-30%; Wherein, the mass concentration of the surfactant auxiliary agent is 5-15%.

7. The composition according to any one of claims 1 to 6, wherein The added amount of the surfactant adjuvant is 20-40% of the total mass of the surfactant A and the surfactant B.

8. The composition according to any one of claims 1 to 7, wherein The oil-water interfacial tension of the surfactant composition is less than 0.005 mN / m.

9. A method for preparing a surfactant composition, characterized in that: The method comprises: (1) dissolving surfactant B into aqueous solution B; (2) mixing a surfactant adjuvant and the aqueous solution B to obtain an aqueous solution A; (3) mixing the surfactant A and the aqueous solution A to obtain a mixture; (4) heating and stirring the mixture until it completely becomes a transparent and uniform liquid; Wherein, the surfactant A is a gemini surfactant, and the surfactant B is a polyoxyethylene ether monomer surfactant.

10. The method according to claim 9, wherein: In the mixture, the mass concentration of the surfactant B is 1-10%, preferably 2-5%.

11. The method according to claim 9, wherein: In the mixture, the mass concentration of the surfactant A is 10-29%, preferably 20-25%.

12. The method according to claim 9, wherein: In the mixture, the mass concentration of the surfactant adjuvant is 5-15%, preferably 5-8%.

13. The method according to claims 9-12, wherein: In step (4), the mixture is heated to 30-60° C.; Preferably, the stirring speed is 200-400 rpm.

14. Use of the surfactant composition according to any one of claims 1 to 8 in chemical combined flooding technology.

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