Acidic microemulsion mixed solution, preparation method and application

Abstract

The invention discloses an acidic microemulsion mixed solution which comprises the following components in percentage by mass: 25-50% of an organic solvent, 15-25% of a surfactant, 4-20% of a cosurfactant, 5-30% of organic acid, 5-20% of inorganic salt, 0.3-2% of a stabilizer and the balance of water. The carbonate rock minerals are selectively dissolved through slow ionization and hydrolysis of the internal organic acid and inorganic salt, the surface roughness of the rock is increased, the hardness of the rock is reduced, then induced cracks are generated, and the permeability-increasing oil displacement effect is further improved by increasing the permeability of the low-permeability compact oil reservoir in a manner of increasing the permeability of the low-permeability compact oil reservoir.

Description

Technical Field

[0001] The invention relates to the technical field of synthesis of compounds for exploitation of low-permeability tight oil reservoirs, and in particular to an acidic microemulsion mixed liquid, a preparation method and application thereof. Background Art

[0002] In recent years, with the deepening of oil and gas exploration, unconventional oil and gas reservoirs have become the key areas of exploration and development, and imbibition and displacement have become important means to increase the production of unconventional oil reservoirs. At present, microemulsion enhanced oil recovery technology has attracted attention and is widely used to improve the performance of injected fluids and achieve the effect of improving oil recovery. The effective components of microemulsions mainly include surfactants, co-surfactants and oil phase solvents, which can improve the wetting of low-permeability tight reservoirs by physical adsorption, reduce surface tension, and interact with organic matter. Patent CN 113214815 uses a mixture of water, oil, surfactants, isopropanol and sodium chloride to provide a nano-microemulsion oil displacement agent with a bicontinuous structure, which can increase the crude oil recovery rate by more than 10 percentage points compared with water flooding.

[0003] However, the chemical agents used to enhance oil recovery reported so far can only change the interface properties to increase the fluidity of crude oil through adsorption, but cannot further increase the flow channels of crude oil. Overall, the effect of permeability enhancement and oil recovery is limited. Summary of the invention

[0004] The purpose of the present invention is to provide an acidic microemulsion mixture, a preparation method and an application thereof, which selectively dissolves carbonate minerals through the slow ionization and hydrolysis of internal organic acids and inorganic salts to increase the roughness of the rock surface, reduce the hardness of the rock and thus induce cracks, and further enhance the permeability and oil recovery effect by increasing the permeability of low-permeability and tight oil reservoirs.

[0005] To achieve the above object, the present invention provides an acidic microemulsion mixture, comprising: 25-50% by mass of an organic solvent, 15-25% by mass of a surfactant, 4-20% by mass of a co-surfactant, 5-30% by mass of an organic acid, 5-20% by mass of an inorganic salt, 0.3-2% by mass of a stabilizer, and the balance being water.

[0006] Optionally, the acidic microemulsion mixture is W / O single-phase droplets, and the particle size of the droplets ranges from 10 to 100 nm.

[0007] The present invention also provides a method for preparing an acidic microemulsion mixture, comprising:

[0008] adding an organic solvent into a system in which the surfactant and the co-surfactant are mixed to obtain an oil phase micelle solution;

[0009] Adding organic acid, inorganic salt and stabilizer into water, stirring and dissolving to obtain an acidic aqueous phase mixed liquid;

[0010] The acidic aqueous phase mixed solution is added into the oil phase micelle solution to obtain an acidic microemulsion mixed solution.

[0011] Optionally, the organic solvent includes at least one or more of the following: limonene, palm oil, turpentine, diesel, white oil, kerosene, n-heptane, toluene, and xylene.

[0012] Optionally, the surfactant includes at least one or more of the following: sorbitan fatty acid ester, nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, polyoxyethylene lauryl ether, polyoxypropylene stearate, hexaethylene glycol monostearate.

[0013] Optionally, the co-surfactant is a small molecule solvent of C4 to C10, wherein the co-surfactant includes at least one or more of the following: ethanol, n-propanol, n-butanol, propylene glycol methyl ether, and triethylene glycol butyl ether.

[0014] Optionally, the organic acid is a weak acid, wherein the organic acid includes at least one or more of the following: formic acid, acetic acid, lactic acid, glyceric acid, butyric acid, oxalic acid, malonic acid, glutaric acid, and chloroacetic acid.

[0015] Optionally, the inorganic salt is a strong acid and weak base salt, wherein the inorganic salt includes at least one or more of the following: ammonium chloride, ammonium nitrate, aluminum chloride, and aluminum nitrate.

[0016] Optionally, the stabilizer includes at least one or more of the following: ethylenediaminetetraacetic acid, nitrilotriacetic acid, and isoascorbic acid.

[0017] Optionally, the mass ratio of the surfactant to the co-surfactant is 5:4 to 4:1.

[0018] Optionally, the mass ratio of the organic acid to the inorganic salt is 3:4 to 2:1.

[0019] The present invention also provides an application of an acidic microemulsion mixed liquid, wherein the acidic microemulsion mixed liquid is applied in a hydraulic fracturing process and a later displacement oil production process in a low-permeability tight oil reservoir.

[0020] Optionally, the application of the acidic microemulsion mixture in the hydraulic fracturing process and subsequent displacement oil recovery of low-permeability tight oil reservoirs includes:

[0021] adding the acidic microemulsion mixture as an additive into the injection liquid;

[0022] injecting the injection liquid into the formation;

[0023] Wherein, the addition amount of the acidic microemulsion mixture is 1-8% of the injected liquid.

[0024] Technical effects and advantages of the present invention:

[0025] 1. The acidic microemulsion mixture provided by the present invention is added with organic acid, and its distribution at the oil-water interface can promote the formation of W / O microemulsion and enhance the stability of the W / O interface film.

[0026] 2. The acidic microemulsion mixed solution provided by the present invention can achieve deep penetration and has a triple slow acidification effect. First, the internal acidic aqueous phase mixed solution is protected by the external organic solvent; second, the ionization of the internal organic acid and the hydrolysis of the strong acid and weak base salt inhibit each other, and the rate of hydrogen ion generation can be reduced by controlling the chemical reaction balance; third, the surfactant will be adsorbed on the rock surface to form a shielding layer, partially inhibiting the contact between the acid and the rock surface. The multiple effects work together to increase the treatment range and the effect.

[0027] 3. The acidic microemulsion mixture provided by the present invention can achieve further permeability enhancement and oil displacement. Compared with conventional microemulsions, it has three modes of increasing reservoir permeability. First, the internal micelles, oil phase and acidic water phase can efficiently dissolve pollutants inside the reservoir and clear the flow channel; second, it can increase the roughness of the rock surface to promote imbibition and replacement; third, it can reduce the hardness of the rock and induce microcracks in other parts to form new flow channels.

[0028] 4. The acidic microemulsion mixed liquid provided by the present invention has a wide range of raw materials to choose from, a simple preparation method, can be quickly dissolved in the injection fluid of the oil reservoir, has low process requirements, has a good permeability enhancement and oil displacement effect, and can be industrially produced and applied.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention is a flow chart of the preparation method of the acidic microemulsion mixture. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings provided by the present invention, and the described embodiments are only part of the embodiments of the present invention, rather than 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 work are within the scope of protection of the present invention.

[0032] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0033] To solve the deficiencies of the prior art, the present invention discloses a W / O acidic microemulsion mixture with an acidic aqueous phase mixture as a dispersed phase and an organic solvent as a continuous phase. In order to better understand the present invention, the principle of improving crude oil recovery rate by the acidic microemulsion mixture is first briefly introduced.

[0034] The acidic microemulsion mixture is a stable W / O microemulsion droplet, which is used as an additive for oil well injection fluid. Due to its small size and large number, it can enter the deep reservoir to play a role. The internal organic acid ionization and inorganic salt hydrolysis can gradually and slowly produce H ions at a controllable speed under formation conditions, selectively and slowly dissolve carbonate minerals in the rock, and further improve the reservoir porosity and permeability conditions by increasing the surface roughness and reducing the rock hardness to induce microcracks without destroying the rock skeleton structure, increase the fluid seepage channel, and change the interface properties and increase the fluidity of crude oil to maximize the interaction between "oil-water imbibition" and "water drive oil" during the development of unconventional oil reservoirs, thereby improving the crude oil recovery rate.

[0035] The acidic microemulsion mixture and its preparation method are introduced in detail below.

[0036] The invention provides an acidic microemulsion mixed liquid, comprising: 25-50% by mass of an organic solvent, 15-25% by mass of a surfactant, 4-20% by mass of an auxiliary surfactant, 5-30% by mass of an organic acid, 5-20% by mass of an inorganic salt, 0.3-2% by mass of a stabilizer, and the balance being water.

[0037] The acidic microemulsion mixture is a stable W / O single-phase droplet with a droplet particle size of 10 to 100 nm.

[0038] The present invention also provides a method for preparing an acidic microemulsion mixture, such as Figure 1 As shown, including:

[0039] 1. Add an organic solvent into the system after the surfactant and the co-surfactant are mixed to obtain an oil phase micelle solution.

[0040] Specifically: at room temperature, the active system of the surfactant and the co-surfactant is evenly mixed in a reaction container, and then an organic solvent is added and magnetically stirred for 10 minutes to evenly mix the internal components to obtain a dispersed and stable oil phase micelle solution.

[0041] Wherein, the organic solvent is one or a combination of limonene, palm oil, turpentine, diesel, white oil, kerosene, n-heptane, toluene and xylene.

[0042] Wherein, the surfactant is a nonionic surfactant with an HLB value between 6 and 10. Preferably, the surfactant is one or a combination of sorbitan fatty acid ester (Span80), nonylphenol polyoxyethylene ether (NP-10), fatty alcohol polyoxyethylene ether (AEO-5), polyoxyethylene lauryl ether, polyoxypropylene stearate, and hexaethylene glycol monostearate.

[0043] The cosurfactant is a small molecule solvent of C4-C10, which can be dissolved in water and polar organic solvents at the same time. Preferably, the cosurfactant is one or a combination of ethanol, n-propanol, n-butanol, propylene glycol methyl ether, triethylene glycol butyl ether.

[0044] Wherein, the mass ratio of the surfactant to the co-surfactant is 5:4 to 4:1.

[0045] 2. Add organic acid, inorganic salt and stabilizer into water, stir and dissolve to obtain acidic aqueous phase mixture.

[0046] Wherein, the organic acid is a weak acid that is not completely ionized in aqueous solution. Preferably, the organic acid is one or a combination of formic acid, acetic acid, lactic acid, glyceric acid, n-butyric acid, oxalic acid, malonic acid, glutaric acid, and chloroacetic acid.

[0047] Wherein, the inorganic salt is a strong acid weak base salt that hydrolyzes in an aqueous solution to generate an acid. Preferably, the inorganic salt is one or a combination of ammonium chloride, ammonium nitrate, aluminum chloride, and aluminum nitrate.

[0048] Wherein, the stabilizer is one or more of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA) and isoascorbic acid.

[0049] Wherein, the mass ratio of the organic acid to the inorganic salt is 3:4 to 2:1.

[0050] 3. Add the acidic aqueous phase mixed solution into the oil phase micelle solution to obtain an acidic microemulsion mixed solution.

[0051] Specifically, under stirring conditions, the acidic aqueous phase mixed solution prepared in step 2 is added dropwise to the oil phase micelle solution prepared in step 1 until the solution begins to change from turbid to transparent, and the acidic microemulsion mixed solution is obtained by aging at room temperature for 24 hours.

[0052] Among them, in the present invention, the amount of clean water has a large selection range, in order to achieve the purpose of dissolving various preparation raw materials.

[0053] The present invention also provides an application of an acidic microemulsion mixture, specifically, the application of the acidic microemulsion mixture in the hydraulic fracturing process and later displacement oil recovery of low-permeability tight oil reservoirs. The specific steps are: adding the acidic microemulsion mixture as an additive to an injection liquid; injecting the injection liquid into a formation; wherein the addition amount of the acidic microemulsion mixture is 1-8% of the injection liquid.

[0054] In order to better explain the present invention, examples are also provided below.

[0055] Example 1

[0056] At room temperature, in a reaction container, 15 g of anhydrous sorbitan fatty acid ester (Span80) surfactant and 5 g of n-propanol co-surfactant are mixed evenly, and then 35 g of limonene organic solvent is added, and magnetic stirring is performed for 10 minutes to mix the internal components evenly to obtain a dispersed and stable oil phase micelle solution; 10 g of acetic acid organic acid, 10 g of inorganic salt aluminum chloride and 1 g of ethylenediaminetetraacetic acid (EDTA) stabilizer are added to 24 g of clean water, and the mixture is stirred until all the raw materials are completely dissolved to obtain an acidic aqueous phase mixed solution; under stirring, the obtained acidic aqueous phase mixed solution is added dropwise to the oil phase micelle solution until the solution begins to change from turbid to clear, and the acidic microemulsion mixed solution formula is obtained by aging at room temperature for 24 hours.

[0057] Example 2

[0058] At room temperature, in a reaction container, 18g of a surfactant (10g of fatty alcohol polyoxyethylene ether AEO-5+8g of anhydrous sorbitan fatty acid ester Span80) and 7g of a propylene glycol methyl ether co-surfactant active system are mixed evenly, and then 30g of an organic solvent (15g of white oil+15g of diesel) is added, and magnetic stirring is performed for 10 minutes to mix the internal components evenly to obtain a dispersed and stable oil phase micelle solution; 18g of lactic acid organic acid, 10g of ammonium chloride inorganic salt and 1.2g of isoascorbic acid stabilizer are added to 15.8g of water, and the mixture is stirred until all the raw materials are completely dissolved to obtain an acidic aqueous phase mixed solution; under stirring, the obtained acidic aqueous phase mixed solution is added dropwise to the oil phase micelle solution until the solution begins to change from turbid to clear, and the acidic microemulsion mixed solution formula is obtained by aging at room temperature for 24h.

[0059] Example 3

[0060] At room temperature, add 20g of a surfactant (10g of fatty alcohol polyoxyethylene ether AEO-5 + 10g of polyoxyethylene lauryl ether) and 8g of an active system of a co-surfactant (4g of ethanol + 4g of triethylene glycol butyl ether) into a reaction container and mix them evenly, then add 20g of an organic solvent (8g of palm oil + 12g of turpentine), and stir magnetically for 10 minutes to mix the internal components evenly to obtain a dispersed and stable oil phase micelle solution; add 15g of an organic acid (10g of formic acid + 5g of n-butyric acid), 8g of an inorganic ammonium nitrate and 1g of an ethylenediaminetetraacetic acid stabilizer into 28g of water, stir until all the raw materials are completely dissolved, and obtain an acidic aqueous phase mixed solution; under stirring, add the obtained acidic aqueous phase mixed solution dropwise into the oil phase micelle solution until the solution begins to change from turbid to clear, and age at room temperature for 24h to obtain an acidic microemulsion mixed solution formula.

[0061] Example 4

[0062] At room temperature, in a reaction container, 18g of nonylphenol polyoxyethylene ether (NP-10) surfactant and 5g of co-surfactant (3g of ethanol + 4g of n-propanol) are mixed evenly, and then 32g of toluene organic solvent is added, and magnetic stirring is performed for 10 minutes to mix the internal components evenly to obtain a dispersed and stable oil phase micelle solution; 20g of formic acid organic acid, 10g of inorganic salt (5g of ammonium chloride + 5g of ammonium nitrate) and 1g of nitrilotriacetic acid (NTA) stabilizer are added to 14g of water, and the mixture is stirred until all the raw materials are completely dissolved to obtain an acidic aqueous phase mixed solution; under stirring, the obtained acidic aqueous phase mixed solution is added dropwise to the oil phase micelle solution until the solution begins to change from turbid to clear, and the acidic microemulsion mixed solution formula is obtained by aging at room temperature for 24h.

[0063] Example 5

[0064] At room temperature, in a reaction container, 20 g of a surfactant (8 g of polyoxyethylene lauryl ether + 12 g of polyoxypropylene stearate) and 5 g of a co-surfactant (2 g of ethanol + 3 g of n-propanol) were mixed evenly, and then 30 g of a limonene organic solvent was added, and magnetic stirring was performed for 10 minutes to mix the internal components evenly to obtain a dispersed and stable oil phase micelle solution; 7.5 g of formic acid organic acid, 10 g of an inorganic salt (5 g of ammonium chloride + 5 g of aluminum chloride) and 1 g of a nitrilotriacetic acid (NTA) stabilizer were added to 26.5 g of water, and the mixture was stirred until all the raw materials were completely dissolved to obtain an acidic aqueous phase mixed solution; under stirring, the obtained acidic aqueous phase mixed solution was added dropwise to the oil phase micelle solution until the solution began to change from turbid to clear, and the acidic microemulsion mixed solution formula was obtained by aging at room temperature for 24 hours.

[0065] Example 6

[0066] At room temperature, in a reaction container, 20 g of an active system of a fatty alcohol polyoxyethylene ether (AEO-5) surfactant and 16 g of a co-surfactant (10 g of propylene glycol methyl ether + 6 g of n-propanol) are mixed evenly, and then 28 g of a turpentine organic solvent is added, and magnetic stirring is performed for 10 minutes to mix the internal components evenly to obtain a dispersed and stable oil phase micelle solution; 10 g of n-butyric acid organic acid, 6 g of an inorganic salt (3 g of ammonium chloride + 7 g of ammonium nitrate) and 1 g of ethylenediaminetetraacetic acid (EDTA) stabilizer are added to 19 g of water, and the mixture is stirred until all the raw materials are completely dissolved to obtain an acidic aqueous phase mixed solution; under stirring, the obtained acidic aqueous phase mixed solution is added dropwise to the oil phase micelle solution until the solution begins to change from turbid to clear, and the acidic microemulsion mixed solution formula is obtained by aging at room temperature for 24 hours.

[0067] In order to further simulate the effect of the acidic microemulsion in hydraulic fracturing and injection fluid displacement of low-permeability tight oil reservoirs, four test fluids were prepared as follows, and the imbibition and oil displacement effects were measured and compared. Among them, the degelling fluid of the polymer fracturing fluid was prepared in accordance with the industry standard SY / T 7627-2021 "Technical Requirements for Water-Based Fracturing Fluids", and the one without adding the acidic microemulsion mixture was used as a blank control.

[0068] Test liquid 1: water

[0069] Test solution 2: water + 1% acid microemulsion mixture

[0070] Test fluid 3: 0.3% polymer fracturing fluid degelling fluid

[0071] Test fluid 4: 0.3% polymer fracturing fluid degelling fluid + 1% acid microemulsion mixed liquid

[0072] Test of the imbibition effect: After the core is dried, its mass m1 is weighed and placed in an intermediate container. The core is saturated with crude oil by vacuum pressure saturation method. The density of crude oil is ρ, and then placed in a 70°C oven for aging for two weeks. After taking it out, wipe the oil sample attached to the surface of the core with oil-absorbing paper, and weigh its mass m2 after drying. The cores are placed in Amott imbibition bottles containing four test liquids to carry out static imbibition experiments. By recording the discharge volume V of the oil phase at different imbibition times t, the imbibition recovery degree R1 of the core is calculated according to the following formula. At the same time, the surface hardness of the core before and after imbibition is measured by a load tester, and the surface roughness of the core before and after imbibition is measured by an atomic mechanics microscope.

[0073]

[0074] Oil displacement effect test: dry the core and put it into the core holder, saturate it with crude oil until all the oil comes out from the outlet, calculate the saturated crude oil volume V1, establish the bound water environment and age it for two weeks. Then inject four prepared test liquids respectively, and when all the outflowing liquid from the outlet is water, measure the cumulative oil output V2 from the outlet, and calculate the displacement recovery rate R2 of the core according to the following formula.

[0075]

[0076] The test results are shown in Table 1.

[0077] Table 1 Test results

[0078]

[0079] It can be clearly seen from the experimental results in Table 1 that the acidic microemulsion mixed solution embodiments (test liquid 2 and test liquid 4) are compared with the blank control examples (test liquid 1 and test liquid 3). Since the acidic medium is contained inside, the surface roughness of the core surface is increased and the surface hardness is reduced after treatment, which can increase the fluid seepage channel and thus improve the recovery rate. The displacement recovery R1 and displacement recovery R2 of the embodiments are increased by 21.9-35.7% compared with the blank control examples. In general, the acidic microemulsion mixture provided by the present invention has a significant permeability-enhancing oil displacement effect.

[0080] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An acidic microemulsion mixture, characterized in that: include: The mass fraction comprises 25-50% organic solvent, 15-25% surfactant, 4-20% co-surfactant, 5-30% organic acid, 5-20% inorganic salt, 0.3-2% stabilizer and the balance is water.

2. The acidic microemulsion mixture according to claim 1, characterized in that The acidic microemulsion mixed liquid is W / O single-phase droplets, and the particle size of the droplets ranges from 10 to 100 nm.

3. A method for preparing an acidic microemulsion mixture, characterized in that: include: adding an organic solvent into a system in which the surfactant and the co-surfactant are mixed to obtain an oil phase micelle solution; Adding organic acid, inorganic salt and stabilizer into water, stirring and dissolving to obtain an acidic aqueous phase mixed liquid; The acidic aqueous phase mixed solution is added into the oil phase micelle solution to obtain an acidic microemulsion mixed solution.

4. The method according to claim 3, characterized in that The organic solvent includes at least one or more of the following: limonene, palm oil, turpentine, diesel, white oil, kerosene, n-heptane, toluene, and xylene.

5. The method according to claim 3, characterized in that: The surfactant includes at least one or more of the following: sorbitan fatty acid ester, nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, polyoxyethylene lauryl ether, polyoxypropylene stearate, hexaethylene glycol monostearate.

6. The method according to claim 3, characterized in that: The co-surfactant is a small molecule solvent of C4-C10, wherein the co-surfactant includes at least one or more of the following: ethanol, n-propanol, n-butanol, propylene glycol methyl ether, and triethylene glycol butyl ether.

7. The method according to claim 3, characterized in that The organic acid is a weak acid, wherein the organic acid includes at least one or more of the following: formic acid, acetic acid, lactic acid, glyceric acid, butyric acid, oxalic acid, malonic acid, glutaric acid, and chloroacetic acid.

8. The method according to claim 3, characterized in that The inorganic salt is a strong acid and weak base salt, wherein the inorganic salt includes at least one or more of the following: ammonium chloride, ammonium nitrate, aluminum chloride, and aluminum nitrate.

9. The method according to claim 3, characterized in that: The stabilizer includes at least one or more of the following: ethylenediaminetetraacetic acid, nitrilotriacetic acid, and isoascorbic acid.

10. The method according to claim 3, characterized in that: The mass ratio of the surfactant to the co-surfactant is 5:4 to 4:

1.

11. The method according to claim 3, characterized in that The mass ratio of the organic acid to the inorganic salt is 3:4 to 2:

1.

12. An application of an acidic microemulsion mixture, characterized in that: The acidic microemulsion mixed liquid is used in the hydraulic fracturing process and later displacement oil production of low-permeability tight oil reservoirs.

13. The use according to claim 12, characterized in that: The application of the acidic microemulsion mixed liquid in the hydraulic fracturing process and later displacement oil recovery of low-permeability tight oil reservoirs includes: adding the acidic microemulsion mixture as an additive into the injection liquid; injecting the injection liquid into the formation; Wherein, the addition amount of the acidic microemulsion mixture is 1-8% of the injected liquid.

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