A nonionic surfactant microemulsion and preparation method thereof

Abstract

The present invention proposes a nonionic surfactant microemulsion and a preparation method thereof, wherein the raw materials of the microemulsion are 100% by weight, including: 0.090%-0.154% of lipophilic nonionic surfactant, 0.069%-0.122% of lipophilic hydrophilic surfactant, 0.030%-0.040% of auxiliary agent, and the balance is water. The preparation method includes adding lipophilic nonionic surfactant, lipophilic hydrophilic nonionic surfactant and auxiliary agent in water, mixing uniformly, and obtaining final product. The microemulsion of the present invention can produce a middle phase with Jiangsu crude oil, and the total recovery rate of microfluidic test reaches 84.30%. The microemulsion flooding recovery rate is increased by 12.40% compared with water flooding, and the oil displacement effect is obvious; in the microemulsion, the surfactant accounts for less than 0.32% of the total weight, and there is no need to add salt and alcohol, and the use cost is low, which is conducive to promotion and application.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, in particular to a nonionic surfactant microemulsion and a preparation method thereof. Background Art

[0002] Tertiary oil recovery technology is the most effective means to improve oil recovery rate. For low-permeability and ultra-low-permeability oil reservoirs, in recent years, with the demand for "substantially improving oil recovery rate", the middle phase microemulsion is an oil-water bicontinuous structure that can solubilize both oil and water, and has good crude oil solubilization and emulsification effects; at the same time, the interfacial tension between the oil and water phases reaches ultra-low, activating the residual oil, thereby significantly improving the oil displacement efficiency.

[0003] In 2023, Zhao Xuezhi et al. proposed a new understanding of "micelle solubilization and emulsification oil carrying" in "New Progress in the Study of Surfactant Oil Flooding Mechanism: Micellar Solubilization and In Situ Emulsification". Surfactant micelles can improve the recovery rate by solubilizing part of the crude oil; it was found that in situ emulsification mainly improves the recovery rate by blocking large pores and emulsification oil carrying, and the solubilization effect of the middle phase microemulsion on the oil phase is the main way to improve the recovery rate, which increases the recovery rate by about 12% compared with water drive; when the surfactant concentration is high, the displacement efficiency can be increased by about 40% compared with water drive, of which 21% is due to the solubilization effect of the microemulsion on the oil, and 19% is due to the trapped oil startup effect caused by the ultra-low IFT caused by the middle phase microemulsion.

[0004] In 2023, Zhou Bingling et al. published a study on the effect of medium-phase microemulsion flooding. They used anionic surfactant sodium dodecyl sulfate (SDS) and orthogonal experiments to obtain the optimal microemulsion system formula: C SDS =4.34%, C 正丁醇 =6.95%,C Na2CO3 =2.17%; oil recovery rate increased by 44.5%, and the water content was also reduced to a very low level.

[0005] In 1997, Hao Jingcheng et al. published "Formation and Properties of Cationic Surfactant-Based Microemulsions," describing a system composed of a quaternary ammonium salt cationic surfactant, sodium chloride, and n-butanol. The main surfactant was a mixture of two cationic surfactants, dioctadecyldimethylammonium chloride and decylpyridinium bromide. The auxiliary agents were 1.3% to 2.2% sodium chloride and at least 1% n-butanol.

[0006] In 1996, Li Fang et al. published a study on the middle phase microemulsion of anionic / cationic surfactant compound system. The anionic surfactant sodium bis-2-ethylhexyl sulfosuccinate (AOT) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) can form a multiphase microemulsion in the presence of alcohol, n-octane and brine. When the molar ratio of AOT to CTAB is 1:7, a middle phase microemulsion is formed.

[0007] Patent CN 116024047: A method for cleaning contaminated oil sand based on a middle phase microemulsion, characterized in that it comprises the following steps: (1) uniformly mixing water, diesel, sodium dodecylbenzene sulfonate, NaCl and n-octanol, and forming a microemulsion phase after stabilization to obtain a middle phase microemulsion; characterized in that the amount of diesel added is 13% of the mass of the water; the amount of sodium dodecylbenzene sulfonate added is 8% of the mass of the water; the amount of NaCl added is 1.5% of the mass of the water; the amount of n-octanol added is 6.0% of the mass of the water; and the amount of sodium silicate added is 0.06% of the mass of the water.

[0008] In the above existing technologies, the middle phase microemulsion usually requires the use of a relatively high concentration of surfactant to be prepared. However, a higher amount of surfactant will lead to higher costs, resulting in an increase in recovery costs. Therefore, how to reduce the amount of surfactant has become one of the technical problems that need to be solved urgently. Summary of the Invention

[0009] In view of this, the present invention proposes a nonionic surfactant microemulsion and a preparation method thereof, aiming to provide a microemulsion that can reduce the amount of surfactant used while maintaining a high recovery rate.

[0010] The technical solution of the present invention is achieved as follows: the present invention provides a nonionic surfactant microemulsion, wherein the raw materials of the microemulsion are 100% by weight and include: 0.090%-0.154% of a lipophilic nonionic surfactant, 0.069%-0.122% of a lipophilic and hydrophilic surfactant, 0.030%-0.040% of an auxiliary agent, and the balance is water.

[0011] In some embodiments, the lipophilic nonionic surfactant in the raw materials includes at least one of fatty amine polyoxyethylene ether, alkyl pyrrolidone and fatty alcohol polyoxyethylene ether.

[0012] In some embodiments, the fatty amine polyoxyethylene ether includes at least one of laurylamine polyoxyethylene ether (AC1202) with an EO addition number of 2, laurylamine polyoxyethylene ether (AC1203) with an EO addition number of 3, octadecylamine polyoxyethylene ether (AC1804) with an EO addition number of 4, and octadecylamine polyoxyethylene ether (AC1805) with an EO addition number of 5.

[0013] In some embodiments, the alkyl pyrrolidone includes at least one of N-octyl pyrrolidone and N-dodecyl pyrrolidone.

[0014] In some embodiments, the fatty alcohol polyoxyethylene ether includes at least one of laurylamine polyoxyethylene ether with an EO addition number of 2 (AEO-2), laurylamine polyoxyethylene ether with an EO addition number of 3 (AEO-3), laurylamine polyoxyethylene ether with an EO addition number of 4 (AEO-4), and laurylamine polyoxyethylene ether with an EO addition number of 5 (AEO-5).

[0015] In some embodiments, the lipophilic and hydrophilic nonionic surfactant includes fatty amine polyoxyethylene ether.

[0016] In some embodiments, the fatty amine polyoxyethylene ether includes at least one of laurylamine polyoxyethylene ether (AC1205) having an EO addition number of 5 and octadecylamine polyoxyethylene ether (AC1810) having an EO addition number of 10.

[0017] In some embodiments, the adjuvant includes isomeric alcohol ethers.

[0018] In some embodiments, the isomeric alcohol ethers include at least one of isomeric decanol polyoxyethylene ether with an EO addition number of 5 (E1005), isomeric decanol polyoxyethylene ether with an EO addition number of 6 (E1006), isomeric decanol polyoxyethylene ether with an EO addition number of 7 (E1007), isomeric decanol polyoxyethylene ether with an EO addition number of 8 (E1008), isomeric decanol polyoxyethylene ether with an EO addition number of 9 (E1009), isomeric tridecanol polyoxyethylene ether with an EO addition number of 7 (E1307), isomeric tridecanol polyoxyethylene ether with an EO addition number of 8 (E1308), isomeric tridecanol polyoxyethylene ether with an EO addition number of 10 (E1310), and isomeric tridecanol polyoxyethylene ether with an EO addition number of 12 (E1312).

[0019] In some embodiments, the water has a salinity of 10,000 mg / L to 90,000 mg / L.

[0020] In a second aspect, the preparation method of the nonionic surfactant microemulsion of the present invention comprises the following steps: adding a lipophilic nonionic surfactant, a lipophilic and hydrophilic nonionic surfactant and an auxiliary agent into water, and mixing them uniformly to obtain the nonionic surfactant microemulsion.

[0021] The present invention has the following beneficial effects compared to the prior art:

[0022] The nonionic surfactant microemulsion of the present invention can generate an intermediate phase with Jiangsu crude oil, and the total recovery rate in the test reaches 84.30%, which is 12.40% higher than that of water flooding, and has a significant oil displacement effect. At the same time, the amount of surfactant used in the microemulsion accounts for less than 0.32% of the total weight, which greatly reduces the amount of surfactant used and the cost of raw materials, is conducive to the practical application and implementation of the microemulsion, and no salt or alcohol needs to be added to the microemulsion, so the cost is low and it is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 Phase diagram of the microemulsion prepared in Example 2 and Jiangsu crude oil;

[0025] Figure 2 This is a cryo-scanning electron micrograph of the mid-phase produced by the microemulsion prepared in Example 2 and Jiangsu crude oil (scale bar is 250 nm);

[0026] Figure 3 This is a photo of the microemulsion flooding prepared in Example 2. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0029] Unless otherwise specified, the methods used in the following examples are conventional methods. The materials, reagents, and instruments used are conventional materials, reagents, and instruments in the art, unless otherwise specified, and can be obtained commercially by those skilled in the art.

[0030] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range. In the present specification and claims, range definitions may be combined and / or interchanged, and if not otherwise stated, such ranges include all subranges contained therein.

[0031] The water used in the following examples and comparative examples was obtained by artificial preparation, and the ion composition of water of various salinities is shown in the following table:

[0032]

[0033] Example 1.

[0034] A nonionic surfactant microemulsion, the raw materials are composed of the following components by weight percentage:

[0035]

[0036] The preparation method of the microemulsion comprises the following steps: adding laurylamine polyoxyethylene ether (AC1203), N-dodecyl pyrrolidone, octadecylamine polyoxyethylene ether (AC1810) and isomeric tridecanol polyoxyethylene ether (E1307) into water and mixing them uniformly to obtain the microemulsion.

[0037] Example 2

[0038] A nonionic surfactant microemulsion, the raw materials are composed of the following components by weight percentage:

[0039]

[0040]

[0041] The preparation method of the microemulsion comprises the following steps: adding laurylamine polyoxyethylene ether (AC1202), N-octyl pyrrolidone, laurylamine polyoxyethylene ether (AC1205) and isomeric decanol polyoxyethylene ether (E1006) into water and mixing them uniformly to obtain the microemulsion.

[0042] Example 3

[0043] A nonionic surfactant microemulsion, the raw materials are composed of the following components by weight percentage:

[0044]

[0045] The preparation method of the microemulsion comprises the following steps: adding octadecylamine polyoxyethylene ether (AC1804), N-octyl pyrrolidone, dodecylamine polyoxyethylene ether (AC1205) and isomeric tridecanol polyoxyethylene ether (E1312) into water and mixing them uniformly to obtain the microemulsion.

[0046] Example 4

[0047] A nonionic surfactant microemulsion, the raw materials are composed of the following components by weight percentage:

[0048]

[0049] The preparation method of the microemulsion comprises the following steps: adding octadecylamine polyoxyethylene ether (AC1805), N-octyl pyrrolidone, octadecylamine polyoxyethylene ether (AC1810) and isomeric decanol polyoxyethylene ether (E1006) into water and mixing them uniformly to obtain the microemulsion.

[0050] Example 5

[0051] A nonionic surfactant microemulsion, the raw materials are composed of the following components by weight percentage:

[0052]

[0053] The preparation method of the microemulsion includes the following steps: adding fatty alcohol polyoxyethylene ether (AEO-5), N-octyl pyrrolidone, dodecylamine polyoxyethylene ether (AC1205) and isomeric decanol polyoxyethylene ether (E1007) into water and mixing them evenly to obtain the microemulsion.

[0054] Comparative Example 1

[0055] A nonionic surfactant microemulsion, the raw materials are composed of the following components by weight percentage:

[0056]

[0057] The preparation method of the microemulsion comprises the following steps: adding dodecylamine polyoxyethylene ether (AC1204), N-dodecyl pyrrolidone, octadecylamine polyoxyethylene ether (AC1810) and isomeric tridecanol polyoxyethylene ether (E1307) into water and mixing them uniformly to obtain the microemulsion.

[0058] Comparative Example 2

[0059] A nonionic surfactant microemulsion, the raw materials are composed of the following components by weight percentage:

[0060]

[0061] The preparation method of the microemulsion comprises the following steps: adding laurylamine polyoxyethylene ether (AC1203), N-dodecyl pyrrolidone, octadecylamine polyoxyethylene ether (AC1809) and isomeric tridecanol polyoxyethylene ether (E1307) into water and mixing them uniformly to obtain the microemulsion.

[0062] Comparative Example 3

[0063] A nonionic surfactant microemulsion, the raw materials are composed of the following components by weight percentage:

[0064]

[0065] The preparation method of the microemulsion comprises the following steps: adding laurylamine polyoxyethylene ether (AC1203), N-dodecyl pyrrolidone, octadecylamine polyoxyethylene ether (AC1810) and isomeric tridecanol polyoxyethylene ether (E1304) into water and mixing them uniformly to obtain the microemulsion.

[0066] Experimental Example 1

[0067] The interfacial tension and wetting properties of the above nonionic surfactant microemulsion were tested respectively, and the results are shown in the following table.

[0068] Grouping Interfacial tension / (mN / m) Contact angle / ° Example 1 0.0048 15.6 Example 2 0.0038 14.5 Example 3 0.0056 16.3 Example 4 0.0043 13.7 Example 5 0.0064 17.6 Comparative Example 1 0.0148 22.4 Comparative Example 2 0.0126 23.1 Comparative Example 3 0.0157 21.8

[0069] The interfacial tension test was conducted in accordance with the oil and gas industry standards. The interfacial tension of the microemulsion prepared with Jiangsu crude oil and Examples 1-5 reached 10 -3 mN / m, reaching ultra-low interface.

[0070] Wettability testing was conducted according to the petroleum and natural gas industry standard, "SY / T 5153: Determination of Wettability of Reservoir Rocks." Using Jiangsu crude oil and the microemulsions prepared in Examples 1-5, wetting reversal was achieved within 24 hours, with contact angles of less than 18°, transforming the oil-wet surface into a strongly water-wet surface.

[0071] Experimental Example 2

[0072] Using a tightly graduated colorimetric tube, Jiangsu crude oil and the microemulsion prepared in Example 2 were added in a volume ratio of 1:1. After gently shaking up and down 50 times, the mixture was placed in a 55°C constant temperature oven and allowed to stand for 3 days. The interface stratification was observed to form a distinct middle phase, as shown in FIG. Figure 1 shown.

[0073] Experimental Example 3

[0074] The middle phase produced by the microemulsion prepared in Example 2 and Jiangsu crude oil was characterized by cryo-scanning electron microscopy. A sponge-like oil-water bicontinuous structure was observed under cryo-scanning electron microscopy, i.e., the middle phase was formed. The observation photos are as follows: Figure 2 shown.

[0075] Experimental Example 4

[0076] Microfluidic testing (2D random microfluidics):

[0077] Displacing phase: microemulsion prepared in Example 2;

[0078] Displaced phase: Jiangsu crude oil, filtered with a 0.8 μm filter membrane.

[0079] The displacement phase injection rate was 10 μL / min, the injection volume was 2.5 ml, the test temperature was 55 °C, and the displacement results were as follows: Figure 3 The displacement can also drive out a large amount of crude oil from the mainstream channel. Crude oil in the non-mainstream channel can also be driven out, but there is a small amount of residual oil. The total recovery rate reaches 84.30%.

[0080] Experimental Example 5

[0081] The method specified in the petroleum and natural gas industry standard "SY / T 5862 Technical Requirements for Oil Displacement Polymers" was followed. Simulated formation water was injected at a flow rate of 0.1 mL / min until the water cut at the production end exceeded 98%. After injecting 1 PV of the microemulsion prepared in Example 2 at a flow rate of 0.1 mL / min, subsequent water flooding was performed until the water cut exceeded 98%. The oil displacement efficiency was then calculated.

[0082] A natural rock core with a length of 8 cm and a diameter of 2.5 cm was used. The core had a porosity of 16.5%, a permeability of 20.3 mD, and a temperature of 55°C. The test was carried out according to the core flooding method. The core water flooding recovery rate was 43.2%. After adding the microemulsion flooding agent, the recovery rate could reach 55.6%, which was 12.4% higher than that of water flooding, and the oil flooding effect was obvious.

[0083] The above description is only a preferred embodiment of the present invention and is 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 nonionic surfactant microemulsion, characterized in that The raw materials of the microemulsion are 100% by weight, including: 0.090%-0.154% of a lipophilic nonionic surfactant, 0.069%-0.122% of a lipophilic and hydrophilic nonionic surfactant, 0.030%-0.040% of an auxiliary agent, and the balance being water. The lipophilic nonionic surfactant is a fatty amine polyoxyethylene ether and an alkyl pyrrolidone, or a fatty alcohol polyoxyethylene ether and an alkyl pyrrolidone, and the fatty amine polyoxyethylene ether is at least one of laurylamine polyoxyethylene ether with an EO addition number of 2 or 3 and octadecylamine polyoxyethylene ether with an EO addition number of 4 or 5. One method comprises the following steps: the alkyl pyrrolidone is at least one of N-octyl pyrrolidone and N-dodecyl pyrrolidone; the fatty alcohol polyoxyethylene ether is at least one of fatty alcohol polyoxyethylene ethers having an EO addition number of 2, 3, 4, or 5; the lipophilic and hydrophilic nonionic surfactant is at least one of dodecylamine polyoxyethylene ether having an EO addition number of 5 and octadecylamine polyoxyethylene ether having an EO addition number of 10; and the auxiliary agent is at least one of isomeric decanol polyoxyethylene ethers having an EO addition number of 5-9 and isomeric tridecanol polyoxyethylene ethers having an EO addition number of 7, 8, 10, or 12.

2. The nonionic surfactant microemulsion according to claim 1, wherein The water has a mineralization degree of 10000 mg / L-90000 mg / L.

3. The method for preparing the nonionic surfactant microemulsion according to any one of claims 1 to 2, characterized in that: The method comprises the following steps: adding a lipophilic nonionic surfactant, a lipophilic and hydrophilic nonionic surfactant and an auxiliary agent into water, and mixing them evenly to obtain the product.

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