An oil displacement surfactant and its preparation method

Abstract

This invention provides an oil displacement surfactant and its preparation method, relating to the field of surfactant technology. An oil displacement surfactant comprises the following raw materials in parts by weight: 10-30 parts of modified sulfonate surfactant, 5-10 parts of modified filler, 3-5 parts of lower alcohol, and 700-1000 parts of water. The preparation method of the modified sulfonate surfactant includes: under a protective atmosphere, stirring and reacting sodium olefin sulfonate, fatty alcohol polyoxyethylene ether, and solvent at temperature T1; adding maleic anhydride and an initiator; adjusting the pH at temperature T2; and rotary evaporation to obtain the final product. The oil displacement surfactant provided by this invention exhibits excellent stability, wettability, and oil recovery rate.

Description

Technical Field

[0001] This invention relates to the field of surfactant technology, and in particular to a surfactant for oil displacement and its preparation method. Background Technology

[0002] Petroleum is a fossil fuel formed from ancient organic matter under long-term high pressure and high temperature in the Earth's crust. Its main components are a mixture of alkanes, cycloalkanes, and aromatics. Its extraction generally involves three stages: primary oil recovery relies on natural energy, with a recovery rate of approximately 15%-20%; secondary oil recovery maintains pressure through water or gas injection, increasing the recovery rate to 25%-40%. However, after the first two stages, about 60% of the crude oil remains in the reservoir, therefore, developing efficient tertiary oil recovery technologies has significant economic value.

[0003] Tertiary oil recovery is primarily chemical flooding, in which surfactants are a key component. Surfactants significantly reduce the interfacial tension between oil, water, and rock surfaces by altering the interactions between them, thereby driving the migration of residual crude oil and improving recovery rates. Surfactants are diverse, including anionic, cationic, zwitterionic, and nonionic types. Currently, sulfonate anionic surfactants are widely used due to their low cost, good water solubility, and excellent interfacial activity, achieving ultra-low interfacial tension even at relatively low concentrations. However, existing surfactants generally face technical challenges such as insufficient salt tolerance and limited recovery efficiency. Therefore, the development of a surfactant for oil displacement and its preparation method is urgently needed, which is of great significance for oil extraction. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes a surfactant for oil displacement and its preparation method.

[0005] The present invention proposes an oil displacement surfactant comprising the following raw materials in parts by weight: 10-30 parts of modified sulfonate surfactant, 5-10 parts of modified filler, 3-5 parts of low carbon alcohol, and 700-1000 parts of water.

[0006] Preferably, the preparation method of the modified sulfonate surfactant includes: stirring sodium olefin sulfonate, fatty alcohol polyoxyethylene ether, and solvent under a protective atmosphere at temperature T1, adding maleic anhydride and initiator to react, adjusting the pH at temperature T2, and rotary evaporating to obtain the product.

[0007] More preferably, T1 is 70-80℃ and T2 is 20-40℃.

[0008] More preferably, the protective gas is selected from one or more of nitrogen and argon.

[0009] More preferably, the sodium olefin sulfonate is selected from one or more of C14-16 α-olefin sulfonate, C16-18 α-olefin sulfonate, and C16-18 intraolefin sulfonate.

[0010] More preferably, the fatty alcohol polyoxyethylene ether is a C12-18 fatty alcohol polyoxyethylene ether.

[0011] More preferably, the solvent is selected from one or more of isopropanol and water.

[0012] More preferably, the volume ratio of isopropanol to water is (1-2):(1-2).

[0013] More preferably, the initiator is dicumyl peroxide.

[0014] More preferably, the pH adjustment is 7-8.

[0015] More preferably, the amount of the initiator is 1.0-1.5 wt% of the total mass of sodium olefin sulfonate, fatty alcohol polyoxyethylene ether, and maleic anhydride.

[0016] More preferably, the mass of the solvent is 2-3 times the total mass of sodium olefin sulfonate and fatty alcohol polyoxyethylene ether.

[0017] More preferably, the molar ratio of sodium olefin sulfonate, fatty alcohol polyoxyethylene ether, and maleic anhydride is 1:(0.8-0.9):(1.1-1.2).

[0018] Preferably, the method for preparing the modified filler includes: heating and mixing ammonium molybdate, thiourea, and water until uniform, then adding silica and silane coupling agent and mixing until uniform, and drying to obtain the filler.

[0019] More preferably, the molar ratio of ammonium molybdate to thiourea is 1:(2-3).

[0020] More preferably, the heating temperature is 200-220°C, and the heating time is 8-10 hours.

[0021] More preferably, the silane coupling agent is selected from one or more of KH550 and KH570.

[0022] More preferably, the mass ratio of the silica to the silane coupling agent is 100:(1-3).

[0023] More preferably, the particle size of the silicon dioxide is 15-200 nm.

[0024] More preferably, the mass ratio of the total mass of ammonium molybdate and thiourea to the mass of silicon dioxide is (10-30):100.

[0025] More preferably, the drying is spray drying.

[0026] Preferably, the lower alcohol is selected from one or more of isopropanol, tert-amyl alcohol, and octanediol.

[0027] The present invention also proposes a method for preparing a surfactant for oil displacement, comprising the following steps: mixing a modified sulfonate surfactant, a modified filler, a low-carbon alcohol, and water evenly to obtain the surfactant.

[0028] The beneficial effects of this invention are as follows:

[0029] In this invention, the modified sulfonate surfactant for oil displacement utilizes a double bond in the MAH group that may exist in the IOS molecule or is grafted via a free radical reaction. Its anhydride ring undergoes ring-opening under alkaline conditions and esterifies with the terminal hydroxyl group of AEO. In the final product, the sulfonate group provides charge and initial hydrophilicity, while the long polyoxyethylene chain resists salt ion attack through steric hindrance and hydration, enhancing its spreading and adsorption on oil-wet rock surfaces. The modified filler facilitates synergistic effects with the modified sulfonate surfactant, improving the oil recovery rate of the oil displacement surfactant. The oil displacement surfactant provided by this invention exhibits excellent stability, wettability, and oil recovery. Attached Figure Description

[0030] Figure 1 This is a bar chart showing the oil recovery rate of the embodiments and comparative examples of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be described in detail through specific embodiments.

[0032] Unless otherwise specified, all materials and reagents used in the following examples and comparative examples are commercially available.

[0033] Example 1

[0034] An oil displacement surfactant comprises the following raw materials in parts by weight: 20 parts modified sulfonate surfactant, 8 parts modified filler, 4 parts isopropanol, and 800 parts water.

[0035] The preparation method of the modified sulfonate surfactant includes: under a nitrogen atmosphere, stirring sodium C14-16 alkenyl sulfonate, fatty alcohol polyoxyethylene ether AEO-9, and solvent at 75°C, adding maleic anhydride and dicumyl peroxide, adjusting the pH to 7 at 30°C, and rotary evaporating to obtain the surfactant; the amount of initiator is 1.0 wt% of the total mass of sodium C14-16 alkenyl sulfonate, fatty alcohol polyoxyethylene ether, and maleic anhydride; the solvent is composed of isopropanol and water in a volume ratio of 1:1, and the mass of the solvent is twice the total mass of sodium C14-16 alkenyl sulfonate and fatty alcohol polyoxyethylene ether; the molar ratio of sodium olefin sulfonate, fatty alcohol polyoxyethylene ether, and maleic anhydride is 1:0.85:1.15.

[0036] The method for preparing the modified filler includes: adding ammonium molybdate and thiourea to water at a molar ratio of 1:2.5 and mixing evenly, hydrothermally treating at 205℃ for 8 hours, adding silica with a particle size of 20nm and KH550 silane coupling agent and mixing evenly, and spray drying to obtain the filler; the mass ratio of silica to silane coupling agent is 100:2; the mass ratio of the total mass of ammonium molybdate and thiourea to the mass of silica is 20:100.

[0037] Example 2

[0038] An oil displacement surfactant comprises the following raw materials in parts by weight: 19 parts modified sulfonate surfactant, 9 parts modified filler, 4 parts octanediol, and 800 parts water.

[0039] The preparation method of the modified sulfonate surfactant includes: under a nitrogen atmosphere, stirring and reacting C16-18 sodium lactone sulfonate, fatty alcohol polyoxyethylene ether, and solvent at 75°C, adding maleic anhydride and dicumyl peroxide, adjusting the pH to 7 at 30°C, and rotary evaporating to obtain the surfactant; the amount of initiator is 1.0 wt% of the total mass of C16-18 sodium lactone sulfonate, fatty alcohol polyoxyethylene ether, and maleic anhydride; the solvent is composed of isopropanol and water in a volume ratio of 1:1, and the mass of the solvent is twice the total mass of C16-18 sodium lactone sulfonate and fatty alcohol polyoxyethylene ether; the molar ratio of sodium lactone sulfonate, fatty alcohol polyoxyethylene ether, and maleic anhydride is 1:0.85:1.15.

[0040] The preparation method of the modified filler is the same as that in Example 1.

[0041] Example 3

[0042] An oil displacement surfactant comprises the following raw materials in parts by weight: 21 parts modified sulfonate surfactant, 7 parts modified filler, 4 parts isopropanol, and 800 parts water.

[0043] The preparation method of the modified sulfonate surfactant is the same as that in Example 1.

[0044] The method for preparing the modified filler includes: adding ammonium molybdate and thiourea to water at a molar ratio of 1:2 and mixing evenly; hydrothermally treating at 200℃ for 8 hours; adding silica with a particle size of 20nm and KH570 silane coupling agent and mixing evenly; and spray drying to obtain the filler; the mass ratio of silica to silane coupling agent is 100:2; and the mass ratio of the total mass of ammonium molybdate and thiourea to the mass of silica is 20:100.

[0045] Comparative Example 1

[0046] The only difference between Comparative Example 1 and Example 1 is that the "modified sulfonate surfactant" in Example 1 is changed to "C14-16 alkenyl sulfonate sodium", and the rest is the same as Example 1.

[0047] Comparative Example 2

[0048] The only difference between Comparative Example 2 and Example 1 is that the "modified filler" in Example 1 is changed to "silica with a particle size of 20nm", and the rest is the same as Example 1.

[0049] The raw materials for the above-mentioned oil displacement surfactant were mixed evenly to obtain the oil displacement surfactant. The above-mentioned oil displacement surfactant was subjected to stability testing, contact angle testing, and oil recovery testing. Specific test conditions were as follows: Stability test: After nitrogen deoxygenation, the sample was sintered and sealed, and aged at 80℃ for 5 days. The presence of precipitation was observed. Contact angle test: The sandstone end face was polished smooth with mirror sandpaper, and the sandstone was washed with toluene and ethanol. After cleaning, it was placed in crude oil, sealed, and stored. It was then placed in a 60℃ constant temperature oven for 40 hours, and the contact angle was measured using a fully automatic contact angle meter. Oil recovery was tested according to the SY-T 6424-2014 standard. The test results are shown in Table 1. Figure 1 As shown.

[0050] Table 1

[0051]

[0052] As shown in Table 1, the oil displacement surfactant prepared by this invention showed no precipitation after aging at 80℃ for 5 days, indicating that the oil displacement surfactant prepared by this invention has excellent stability. The oil displacement surfactant prepared by this invention has a small contact angle, indicating that the oil displacement surfactant prepared by this invention has excellent wettability. The oil displacement surfactant prepared by this invention has a high recovery rate, meaning that the recovery rate is high even with a small amount of oil displacement surfactant used. Comparative Example 1 shows that changing the "modified sulfonate surfactant" to "C14-16 alkenyl sulfonate sodium" significantly increased the contact angle and decreased the recovery rate; Comparative Example 2 shows that changing the "modified filler" to "silica with a particle size of 20 nm" led to precipitation.

[0053] In summary, the oil displacement surfactant provided by this invention has excellent stability, wettability, and oil recovery rate.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A surfactant for oil displacement, characterized in that, The raw materials include the following parts by weight: 10-30 parts modified sulfonate surfactant, 5-10 parts modified filler, 3-5 parts low alcohol, and 700-1000 parts water; The preparation method of the modified sulfonate surfactant includes: stirring sodium olefin sulfonate, fatty alcohol polyoxyethylene ether, and solvent under a protective atmosphere at temperature T1, adding maleic anhydride and initiator, adjusting the pH at temperature T2, and then rotary evaporating to obtain the product.

2. The surfactant for oil displacement according to claim 1, characterized in that, The T1 is 70-80℃, and the T2 is 20-40℃.

3. The surfactant for oil displacement according to claim 1, characterized in that, The protective gas is selected from one or more of nitrogen and argon; the sodium olefin sulfonate is selected from one or more of C14-16 α-olefin sulfonate, C16-18 α-olefin sulfonate, and C16-18 inner olefin sulfonate; the fatty alcohol polyoxyethylene ether is a C12-18 fatty alcohol polyoxyethylene ether.

4. The surfactant for oil displacement according to claim 1, characterized in that, The solvent is selected from one or more of isopropanol and water; the volume ratio of isopropanol to water is (1-2):(1-2); the initiator is dicumyl peroxide; and the pH is adjusted to 7-8.

5. The surfactant for oil displacement according to claim 1, characterized in that, The amount of the initiator is 1.0-1.5 wt% of the total mass of sodium olefin sulfonate, fatty alcohol polyoxyethylene ether, and maleic anhydride; the mass of the solvent is 2-3 times the total mass of sodium olefin sulfonate and fatty alcohol polyoxyethylene ether; the molar ratio of sodium olefin sulfonate, fatty alcohol polyoxyethylene ether, and maleic anhydride is 1:(0.8-0.9):(1.1-1.2).

6. The surfactant for oil displacement according to claim 1, characterized in that, The method for preparing the modified filler includes: heating and mixing ammonium molybdate, thiourea, and water until uniform, then adding silica and silane coupling agent and mixing until uniform, and drying to obtain the filler.

7. The surfactant for oil displacement according to claim 6, characterized in that, The molar ratio of ammonium molybdate to thiourea is 1:(2-3); the heating temperature is 200-220℃, and the heating time is 8-10h; the silane coupling agent is selected from one or more of KH550 and KH570.

8. The surfactant for oil displacement according to claim 6, characterized in that, The mass ratio of silica to silane coupling agent is 100:(1-3); the particle size of silica is 15-200nm; the mass ratio of the total mass of ammonium molybdate and thiourea to silica is (10-30):100; the drying is spray drying.

9. The surfactant for oil displacement according to claim 1, characterized in that, The lower alcohol is selected from one or more of isopropanol, tert-amyl alcohol, and octanediol.

10. A method for preparing an oil displacement surfactant according to any one of claims 1-9, characterized in that, Includes the following steps: The modified sulfonate surfactant, modified filler, low carbon alcohol, and water are mixed evenly to obtain the final product.

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