Preparation method of in-situ self-borne double-emulsion fracturing fluid with double-soluble micro-nano proppant with core-shell structure

Abstract

The application belongs to the technical field of petroleum fracturing proppant preparation, and particularly relates to a preparation method of an in-situ self-grown core-shell structure double-repellent micro-nano proppant double-emulsion fracturing fluid. The application uses sodium silicate, a silane coupling agent and ethyl lactate as proppant core material precursor materials, uses a thermosetting resin as a proppant shell layer precursor material, and uses double-repellent modification materials and a drag-reducing agent as precursor materials of the double-repellent surface, so that the cost is reduced, and the strength of the proppant and the flow permeation and drag reduction capacity thereof are improved.

Description

Technical Field

[0001] This invention belongs to the field of petroleum fracturing proppant preparation technology, specifically relating to a method for preparing an in-situ self-generated core-shell structure dual-hydrophobic micro-nano proppant dual-emulsion fracturing fluid. Background Technology

[0002] Horizontal well volumetric fracturing is an effective means of achieving economical development of shale oil. However, the differences in mineral composition and the widespread distribution of discontinuous interfaces within shale reservoirs result in strong heterogeneity, leading to more complex and tortuous fractures. Conventional solid proppant particles are large (>210μm), making it difficult to deliver them to the distal ends of the main fractures. The microfractures at the distal ends of the complex fracture network formed during fracturing cannot be effectively supported and are prone to re-closure under formation closure pressure, resulting in numerous fracture failures and severely impacting the release of reservoir productivity at the distal end of the wellbore. In-situ self-generated proppant, a special component of fracturing fluid, is in-situ transformed into solid particles through physical or chemical reactions under reservoir conditions to support the microfractures at the distal ends of the complex fracture network. This provides a high-conductivity channel for oil and gas flow, further improving the effectiveness of volumetric fracturing development in shale reservoirs.

[0003] In recent years, scholars at home and abroad have also conducted extensive research on in-situ self-generated proppants. Reference 1 (Qu Zhanqing et al. Preparation and evaluation of epoxy resin phase change proppant based on Pickering emulsification technology [J]. Journal of China University of Petroleum (Natural Science Edition), 2023, 47(4): 111-118.) selected polymer phase change materials or thermosetting resins such as phenolic and epoxy resins as raw materials, added curing agents and other additives, and prepared liquid systems that can generate proppants in situ through solution blending or emulsification; however, such organic proppants are prone to shrinkage, deformation or aging under deep high temperature and high pressure conditions, which will affect the long-term conductivity of cracks. Reference 2 (Fan J., et al. Development of self-generated proppant based on modified lowdensity and low-viscosity epoxy resin and its evaluation[J]. Petroleum Science, 2022, 19: 224-252.) investigated the effects of reinforcing materials such as elastic rubber particles, silica, and graphene particles on the strength of thermosetting epoxy resins, finding that 3 wt.% graphene particles could increase the compressive strength by more than 40%. Although this significantly improves the mechanical properties of in-situ self-generated proppants, the high cost of polymeric materials and nano-additives compared to inorganic materials severely limits the large-scale application of such proppants. Reference 3 (Tong S., et al. In situgenerated proppants for shale reservoirs[J]. Fuel, 2022, 319:123776.) utilizes calcite from shale as a calcium source, reacting in situ with phosphate components in fracturing fluid to generate hydroxyapatite crystals as a proppant on the fracture surface, thereby improving fracture conductivity. Although inorganic particles significantly improve the compressive strength of high-molecular-weight microspheres and substantially reduce material costs, fractures, as the reaction site for inorganic materials, are relatively large in scale, making it difficult to control the morphology and size of in-situ self-generated inorganic proppants. Furthermore, the migration of fragmented particles under high closure pressure poses a significant risk of blockage. Therefore, maintaining higher compressive strength and resistance to fragmentation while preserving the morphology of the in-situ self-generated proppant is crucial. Summary of the Invention

[0004] To address the aforementioned problems, this invention employs a two-step emulsification method to construct an in-situ self-generated core-shell structure dual-hydrophobic micro / nano proppant dual-emulsion fracturing fluid (such as...). Figure 1 As shown, the core-shell structure and double-hydrophobic surface maintain particle morphology and strength, reduce the proportion of organic materials, lower the cost of proppant, achieve seepage resistance reduction, and maintain the long-term conductivity of cracks.

[0005] To achieve the above objectives, this invention provides a method for preparing an in-situ self-generated core-shell structure dual-hydrophobic micro / nano proppant dual-emulsion fracturing fluid. By using sodium silicate, silane coupling agent, and ethyl lactate as precursor materials for the proppant core, a thermosetting resin as the precursor material for the proppant shell, and dual-hydrophobic modification materials and drag-reducing agents as precursor materials for the dual-hydrophobic surface, this method reduces costs while improving the strength of the proppant and its permeation drag-reducing ability. Specifically, this invention first constructs a water-in-oil (W / O) emulsion, then uses the W / O emulsion as the internal phase and a mixed solution of the dual-hydrophobic modification materials and drag-reducing agents as the external phase to construct a water-in-oil (W / O / W) dual emulsion, namely, an in-situ self-generated core-shell structure dual-hydrophobic micro / nano proppant dual-emulsion fracturing fluid.

[0006] This invention provides a method for preparing an in-situ self-generated core-shell structured dual-hydrophobic micro / nano proppant dual-emulsion hydraulic fracturing fluid, the preparation method comprising the following steps:

[0007] S1. Dissolve 1-5 parts of sodium silicate, 1-5 parts of ethyl lactate, and 0.1-1 parts of silane coupling agent in 10-20 parts of water to obtain the internal aqueous phase W1.

[0008] S2. Mix 10-20 parts of thermosetting resin with 2-10 parts of compound emulsifier A and 1-5 parts of curing agent, and stir at 500-800 rpm for 0.5-2 h to obtain oil phase O.

[0009] S3. Add the internal aqueous phase W1 dropwise to the oil phase O at a rate of 3-9 mL / min, set the rotation speed to 1000-1500 rpm, and stir for 0.5-2 h to form a W / O emulsion.

[0010] S4. Dissolve 0.1-1 parts of the dual-hydrophobic modification material, 0.01-0.5 parts of the drag reducer, 2-10 parts of the compound emulsifier B, and 1-5 parts of the reinforcing agent in 30-50 parts of water to form the external aqueous phase W2.

[0011] S5. Take the W / O emulsion formed in S3 and add it dropwise to the external aqueous phase W2 at a rate of 3-9 mL / min. Stir during the addition process at a speed of 700-1000 rpm and a temperature of 40-60℃. After the addition is complete, continue stirring for 10-60 min to obtain the in-situ self-generated core-shell structure dual hydrophobic micro-nano proppant dual emulsion fracturing fluid.

[0012] The silane coupling agent mentioned in step S1 of the present invention is one of KH-550, KH-560, and KH-570, preferably KH-550.

[0013] The thermosetting resin mentioned in step S2 of the present invention is one or more of phenolic resin, epoxy resin, and unsaturated polyester resin, preferably epoxy resin.

[0014] The number average molecular weight of the thermosetting resin is 350-550 g / mol.

[0015] In step S2 of this invention, the compound emulsifier A is a mixed solution of Span 80 and Tween 80 in a mass ratio of (1~4):1, used to construct a W / O emulsion. The curing agent is one or more of m-phenylenediamine, methylcyclohexanediamine, methyltetrahydrophthalic anhydride, and 4,4'-diaminodiphenyl sulfone, used for the curing and growth of the support at 80-100°C; preferably methylcyclohexanediamine.

[0016] The dual-hydrophobic modifier in step S4 of this invention is at least one of dodecafluoroheptyl methacrylate, tridecafluorooctyl methacrylate, and ethyl 2-perfluorooctyl acrylate, preferably ethyl 2-perfluorooctyl acrylate; the drag-reducing agent is at least one of cationic polyacrylamide, anionic polyacrylamide, and amphoteric polyacrylamide, preferably anionic polyacrylamide; the compound emulsifier B is a mixed solution of Tween 80 and op-10, preferably in a mass ratio of (5~9):1; the reinforcing agent is at least one of silica fume and attapulgite, preferably silica fume.

[0017] Preferably, the particle size of the reinforcing agent is no greater than 1250 mesh.

[0018] The in-situ self-generated core-shell structure dual-hydrophobic micro / nano proppant double emulsion hydraulic fracturing fluid was cured at 80-100℃ for 3-4 hours to obtain proppant-cured particles with a particle size of 80-150 μm and a bulk density of 1.1-1.5 g / cm³. 3 The water contact angle is 145-160°, the oil contact angle is 130-145°, and the breakage rate at 40MPa is 3.5-6.8%.

[0019] The beneficial effects of this invention are as follows:

[0020] (1) The fracturing fluid prepared by the present invention no longer requires a suspended solid proppant, which greatly reduces the amount of thickener, crosslinking agent and other components. This not only reduces the frictional resistance of the fracturing fluid and the wear on pipeline equipment, saving energy, but also reduces the thickener residue that damages the conductivity of the fracture, maximizing the seepage capacity of the fracture network.

[0021] (2) The present invention creatively achieves controllable particle size of proppant by changing the amount of emulsifier and the oil-water ratio of W / O emulsion. The solid particles formed by solidification have better migration ability than conventional solid proppant, which is more conducive to supporting microcracks at the far end of complex seam mesh.

[0022] (3) The fracturing fluid provided by the present invention can achieve in-situ self-generation, so that wherever the fracturing fluid flows, the proppant is generated in-situ, thus realizing the integration of fracturing and proppant, simplifying the injection process and reducing material costs.

[0023] (4) The fracturing fluid prepared by the present invention not only overcomes the problems of high cost and low strength after curing of conventional organic liquid proppant, but also significantly reduces the fluid seepage resistance of the micro-nano proppant filling layer, maintains the long-term flow capacity of the micro-cracks at the far end of the fracture network, and improves the fracturing effect. Attached Figure Description

[0024] Figure 1 Schematic diagram of in-situ self-generated core-shell structure dual-hydrophobic microsupporter dual-emulsion hydraulic fracturing fluid and filling microcracks;

[0025] Figure 2 Microscopic images of the W / O emulsion prepared in Example 1;

[0026] Figure 3 Microscopic images of the fracturing fluid prepared in Example 1;

[0027] Figure 4 The aqueous phase contact angles are those of Examples 1-3 and Comparative Example 4.

[0028] Figure 5 The contact angles of the oil phase in Examples 1-3 and Comparative Example 4 are given. Detailed Implementation

[0029] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention. However, the scope of protection of the present invention is not limited to these embodiments. All changes or equivalent substitutions that do not depart from the concept of the present invention are included within the scope of protection of the present invention.

[0030] In the following examples and comparative examples, sodium silicate, KH-550, and ethyl lactate were all analytical grade; silica powder, >98%, -1250 mesh, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; Span80, Tween80, and op-10 were all chemically pure from Sinopharm Chemical Reagent Co., Ltd.; anionic polyacrylamide, model BM73020, was purchased from Shandong Baomo Biochemical Co., Ltd.; ethyl 2-perfluorooctyl acrylate and methylcyclohexanediamine were both analytical grade from Shanghai Aladdin Biochemical Technology Co., Ltd.; epoxy resin was purchased from Kunshan Jiulimei Electronic Materials Co., Ltd., model GCC135, with an epoxy value of 0.57.

[0031] The technical solution of the present invention will be further described below with reference to the embodiments.

[0032] Example 1

[0033] A method for preparing an in-situ self-generated core-shell structured dual-hydrophobic micro / nano proppant dual-emulsion hydraulic fracturing fluid includes the following steps:

[0034] Take 2 g of sodium silicate, 0.5 g of KH-550 and 2 g of ethyl lactate and dissolve them in 15 g of water to obtain the internal aqueous phase W1;

[0035] Take 17 g of epoxy resin, 5 g of compound emulsifier A and 3.5 g of methylcyclohexanediamine and mix them. Stir at 700 rpm for 1 h to obtain oil phase O.

[0036] Under the conditions of stirring speed of 1000 rpm and emulsification temperature of 40℃, the inner aqueous phase W1 was added dropwise to the oil phase O at a rate of 5 mL / min and emulsified for 50 min to obtain a W / O emulsion.

[0037] Take 0.2 g of ethyl 2-perfluorooctyl acrylate, 4.8 g of compound emulsifier B, 0.1 g of anionic polyacrylamide, and 2.9 g of silica powder and dissolve them in 47 g of water to form the external aqueous phase W2;

[0038] Then, at a stirring speed of 800 rpm and an emulsification temperature of 45℃, the W / O emulsion was dropped into the external aqueous phase W2 at a rate of 5 mL / min, and the mixture was stirred and emulsified for 50 min to obtain an in-situ self-generated core-shell structured dual-hydrophobic micropropped fracturing fluid.

[0039] The compound emulsifier A is Span80 and Tween80 in a mass ratio of 1:1; the compound emulsifier B is Tween80 and op-10 in a mass ratio of 9:1.

[0040] After the fracturing fluid is evenly dispersed, it is cured at 90°C for 3 hours to obtain proppant-cured particles.

[0041] Example 2

[0042] A method for preparing an in-situ self-generated core-shell structured dual-hydrophobic micro / nano proppant dual-emulsion hydraulic fracturing fluid includes the following steps:

[0043] Take 2g of sodium silicate, 0.6g of KH-550 and 3g of ethyl lactate and dissolve them in 15g of water to obtain the internal aqueous phase W1;

[0044] Take 16g of epoxy resin, 6g of compound emulsifier A and 4g of methylcyclohexanediamine and mix them. Stir at 700rpm for 1h to obtain oil phase O.

[0045] Under the conditions of stirring speed of 1000 rpm and emulsification temperature of 40℃, the inner aqueous phase W1 was added dropwise to the oil phase O at a rate of 5 mL / min and emulsified for 50 min to obtain a W / O emulsion.

[0046] Take 0.3g of ethyl 2-perfluorooctyl acrylate, 4.8g of compound emulsifier B, 0.2g of anionic polyacrylamide, and 3.5g of silica powder and dissolve them in 46g of water to form the external aqueous phase W2;

[0047] Then, at a stirring speed of 800 rpm and an emulsification temperature of 45℃, the W / O emulsion was dropped into the external aqueous phase W2 at a rate of 5 mL / min, and the mixture was stirred and emulsified for 50 min to obtain an in-situ self-generated core-shell structured dual-hydrophobic micropropped fracturing fluid.

[0048] The compound emulsifier A is Span80 and Tween80 in a mass ratio of 1:1; the compound emulsifier B is Tween80 and op-10 in a mass ratio of 9:1.

[0049] After the fracturing fluid is evenly dispersed, it is cured at 100°C for 4 hours to obtain proppant cured particles.

[0050] Example 3

[0051] Take 2g of sodium silicate, 0.7g of KH-550 and 4g of ethyl lactate and dissolve them in 15g of water to obtain the internal aqueous phase W1;

[0052] Take 15g of epoxy resin, 7g of compound emulsifier A and 4.5g of methylcyclohexanediamine and mix them. Stir at 700rpm for 1h to obtain oil phase O.

[0053] Under the conditions of stirring speed of 1000 rpm and emulsification temperature of 40℃, the inner aqueous phase W1 was added dropwise to the oil phase O at a rate of 5 mL / min and emulsified for 50 min to obtain a W / O emulsion.

[0054] Take 0.3g of ethyl 2-perfluorooctyl acrylate, 4.8g of compound emulsifier B, 0.3g of anionic polyacrylamide, and 4g of silica powder and dissolve them in 45g of water to form the external aqueous phase W2;

[0055] Then, at a stirring speed of 800 rpm and an emulsification temperature of 45℃, the W / O emulsion was dropped into the external aqueous phase W2 at a rate of 8 mL / min, and the mixture was stirred and emulsified for 50 min to obtain a core-shell structured dual-proppant fracturing fluid.

[0056] The compound emulsifier A is Span80 and Tween80 in a mass ratio of 1:1; the compound emulsifier B is Tween80 and op-10 in a mass ratio of 9:1.

[0057] After the fracturing fluid is evenly dispersed, it is cured at 80°C for 4 hours to obtain proppant-cured particles.

[0058] Comparative Example 1

[0059] The preparation conditions for this comparative example are the same as in Example 1, except that the amount of sodium silicate used is 10g.

[0060] Comparative Example 2

[0061] The preparation conditions for this comparative example are the same as in Example 1, except that the mass of epoxy resin in the oil phase is 30g.

[0062] Comparative Example 3

[0063] The preparation conditions for this comparative example are the same as in Example 1, except that the mass of compound emulsifier A is 15g and the mass of compound emulsifier B is 15g.

[0064] Comparative Example 4

[0065] The preparation conditions for this comparative example are the same as in Example 1, except that the mass of KH-550 is 3g.

[0066] Test Example 1

[0067] This test example uses a microscope to observe the W / O emulsions and in-situ self-generated core-shell structure dual-hydrophobic micro / nano proppant dual-emulsion fracturing fluids prepared in each embodiment and comparative example, and performs particle size detection. Figure 2 , 3 Microscopic images of the W / O emulsion and fracturing fluid prepared in Example 1 are shown. Table 1 shows the median droplet size distribution of the W / O emulsion and fracturing fluid prepared in each example and comparative example. As can be seen from Table 1, the median droplet size of the fracturing fluid prepared in Examples 1-3 is 102~109 μm; the median droplet size of the fracturing fluid prepared in Comparative Examples 1 and 2 is much higher than that in Examples 1-3. This is because the adjustment of the oil-water ratio affects the particle size of the proppant.

[0068] Table 1. Droplet size distribution in W / O emulsions and fracturing fluids

[0069]

[0070] Test Example 2

[0071] The breakage rate of the proppant-cured particles prepared in Examples 1-3 and Comparative Examples 1-4 was tested. The test method referred to "SY / T5108-2014 Performance of Proppants for Hydraulic Fracturing and Gravel Packing Operations". The specific method was as follows: ① First, a certain mass (m1) of proppant-cured particle sample was weighed and added to the crushing chamber; ② The experiment was conducted under 40 MPa conditions, with the crushing chamber placed in the middle of the test platform; ③ The tested proppant-cured particles were placed in a sieve and vibrated for 10 min. The mass (m2) of the broken proppant-cured particles that were sieved was weighed. The breakage rate of the proppant-cured particles was obtained by comparing m1 and m2. The specific results are shown in Table 2.

[0072] Table 2. Test results of the breakage rate of proppant-cured particles

[0073]

[0074] Proppant is a primary material used in hydraulic fracturing, playing a decisive role in the success of fracturing operations, especially in supporting guiding fractures. Compressive strength is a crucial criterion for evaluating proppant performance; only with high compressive strength can it resist the pressure of overlying and formation pressures, effectively support microfractures at the distal end of complex fracture networks, and improve the fracturing effect in shale reservoirs. Table 2 shows that the solid proppant particles obtained by solidifying in-situ self-generated core-shell structure dual-hydrophobic micro-nano proppant with dual-emulsion fracturing fluid exhibit relatively high compressive strength. This may be due to the effective addition of silica powder, which enhances the compressive strength of the solidified proppant particles. Silica powder, as a filler, can effectively improve the various properties of the solidified product when added to organic resins. Furthermore, silica powder is relatively inexpensive, and its addition to resins can reduce overall costs without compromising product quality. Furthermore, compared to Examples 1-3, the breakage rate of the proppant cured particles obtained in Comparative Examples 1-3 was significantly improved. This is because the oil-water ratio of the W / O emulsion affects the droplet size of the emulsion and the stability of the two emulsions, thereby affecting the compressive strength of the cured proppant particles.

[0075] Test Example 3

[0076] The bulk density of the proppant-cured particles obtained from each embodiment and comparative example was tested. The test method referred to "SY / T5108-2014 Performance of Proppants for Hydraulic Fracturing and Gravel Packing Operations". The specific method was as follows: ① Prepare 3 samples of proppant-cured particles; ② Weigh the mass m of a 100 mL density bottle. g ③ Pack the sample into a density bottle, weigh the total mass m0 of the density bottle and the sample, and take the average value three times; ④ Calculate the bulk density of the proppant solidified particles according to the following formula.

[0077] (Equation 1)

[0078] In the formula —Prop curing particle bulk density, g·cm³ -3 ;

[0079] —Total mass of the density bottle and sample, in g;

[0080] —The mass of the density bottle, in grams;

[0081] —Volume of the density bottle, in cm³ 3 .

[0082] Table 3. Bulk density of proppant cured particles

[0083]

[0084] Bulk density refers to the mass of proppant per unit volume. The amount of proppant used during fracturing is determined by its bulk density. A higher bulk density means a higher proppant quantity is required, and vice versa. As shown in Table 3, the bulk density of the solidified proppant particles obtained in Examples 1-3 is relatively low. This is because the dual-emulsion emulsification effect is good, resulting in smaller emulsion droplet sizes. The smaller the solid particles formed after solidification, the lower the bulk density.

[0085] Test Example 4

[0086] Contact angle performance tests were performed on the proppant-cured particles obtained from each embodiment and comparative example. The droplet morphology on the surface of the tablets made from the proppant-cured particles was photographed using a contact angle meter. At room temperature, the instrument camera was adjusted until the image of the tablet slice was clear. Pure water / oil was drawn up, and the height of the sampler was adjusted so that the screen could display a clear needle image. 2 μL of water / oil was dropped onto the tablet, and the contact angle value was read after the liquid formed a stable phase contact angle on the tablet surface.

[0087] Table 4 Contact Angle Test Results

[0088]

[0089] like Figure 4 , 5 The aqueous phase contact angles and oil phase contact angles of Examples 1-3 and Comparative Example 4 are shown in Table 4, from left to right: Example 1, Example 2, Example 3, and Comparative Example 4. The test results are shown in Table 4. The contact angle test results indicate that Examples 1-3 successfully prepared bihydrophobic modified microproppanes, and the bihydrophobic properties of the modified microproppanes improved with increasing amounts of silane coupling agent KH-550 and bihydrophobic materials. However, the aqueous phase contact angle and oil phase contact angle of Comparative Example 4 were smaller than those of Examples 1-3. This is because the KH-550 silane coupling agent hydrolyzed under high concentration conditions underwent a self-polymerization reaction, resulting in fewer KH-550 molecules actually grafted onto the proppant surface. This manifests as weaker hydrophobicity on the surface of the solidified proppant particles and a weaker modification effect.

Claims

1. A method for preparing an in-situ self-generated core-shell structured dual-hydrophobic micro / nano-supported dual-emulsion hydraulic fracturing fluid, characterized in that, Includes the following steps: S1. Dissolve 1-5 parts of sodium silicate, 1-5 parts of ethyl lactate, and 0.1-1 parts of silane coupling agent in 10-20 parts of water to obtain the internal aqueous phase W1. S2. Mix 10-20 parts of thermosetting resin with 2-10 parts of compound emulsifier A and 1-5 parts of curing agent, and stir at 500-800 rpm for 0.5-2 h to obtain oil phase O. S3. Add the internal aqueous phase W1 dropwise to the oil phase O at a rate of 3-9 mL / min, set the rotation speed to 1000-1500 rpm, and stir for 0.5-2 h to form a W / O emulsion. S4. Dissolve 0.1-1 parts of the dual-hydrophobic modification material, 0.01-0.5 parts of the drag reducer, 2-10 parts of the compound emulsifier B, and 1-5 parts of the reinforcing agent in 30-50 parts of water to form the external aqueous phase W2. S5. Take the W / O emulsion formed in S3 and add it dropwise to the external aqueous phase W2 at a rate of 3-9 mL / min. Stir during the addition process at a speed of 700-1000 rpm and a temperature of 40-60℃. After the addition is complete, continue stirring for 10-60 min to obtain the in-situ self-generated core-shell structure dual hydrophobic micro-nano proppant dual emulsion fracturing fluid. The thermosetting resin mentioned in step S2 is epoxy resin; The compound emulsifier A is a mixed solution of Span80 and Tween80; The curing agent is one or more of m-phenylenediamine, methylcyclohexanediamine, methyltetrahydrophthalic anhydride, and 4,4'-diaminodiphenyl sulfone. The dihydrophobic modifier in step S4 is at least one of dodecafluoroheptyl methacrylate, tridecafluorooctyl methacrylate, and ethyl 2-perfluorooctyl acrylate; The drag-reducing agent is at least one of cationic polyacrylamide, anionic polyacrylamide, and amphoteric polyacrylamide; The compound emulsifier B is a mixed solution of Tween80 and op-10; The reinforcing agent is at least one of silica fume and attapulgite.

2. The preparation method according to claim 1, characterized in that, The silane coupling agent mentioned in step S1 is one of KH-550, KH-560, and KH-570.

3. The preparation method according to claim 1, characterized in that, The thermosetting resin mentioned in step S2 is epoxy resin.

4. The preparation method according to claim 1, characterized in that, The compound emulsifier A mentioned in step S2 is a mixed solution of Span80 and Tween80 with a mass ratio of (1~4):

1.

5. The preparation method according to claim 1, characterized in that, The curing agent mentioned in step S2 is methylcyclohexanediamine.

6. The preparation method according to claim 1, characterized in that, The bis-hydrophobic modifier in step S4 is ethyl 2-perfluorooctyl acrylate; The drag-reducing agent is anionic polyacrylamide.

7. The preparation method according to claim 1, characterized in that, The compound emulsifier B is a mixed solution of Tween80 and op-10 with a mass ratio of (5~9):

1.

8. The preparation method according to claim 1, characterized in that, The reinforcing agent is silica powder.

9. The preparation method according to claim 1, characterized in that, The particle size of the reinforcing agent is no greater than 1250 mesh.

10. The preparation method according to any one of claims 1-9, characterized in that, The in-situ self-generated core-shell structure dual-hydrophobic micro / nano proppant double emulsion hydraulic fracturing fluid was cured at 80-100℃ for 3-4 hours to obtain proppant-cured particles. The proppant-cured particles had a particle size of 80-150 μm and a bulk density of 1.1-1.5 g / cm³. 3 The water contact angle is 145-160°, the oil contact angle is 130-145°, and the breakage rate at 40MPa is 3.5-6.8%.

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