Ceramic particle proppant with porous single-permeable structure for hydraulic fracturing and preparation method of ceramic particle proppant

Abstract

The invention belongs to the technical field of shale gas exploitation, and provides a ceramic particle proppant with a porous single-permeable structure for hydraulic fracturing and a preparation method of the ceramic particle proppant. The preparation method comprises the following steps: pre-treating raw materials, and sequentially mixing, granulating, carrying out compression molding, sintering, crushing, screening and carrying out hydrophobic treatment to obtain the ceramic particle proppant with the porous one-way transparent structure. According to the preparation method, the ceramic particles are subjected to super-hydrophobic surface modification under the specific pore diameter of the ceramic particles, and the light water-blocking and methane-permeable porous particles are obtained. The porous ceramic particle proppant is low in density and can suspend in fracturing fluid, CH4 gas can penetrate through pores of the porous ceramic particle proppant, the fracturing fluid is impermeable, and the particle suspension and anti-reflection functions are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of shale gas exploitation, and particularly to a ceramic particle proppant with a porous unidirectional permeability structure for hydraulic fracturing and a preparation method thereof. Background Art

[0002] With the increasing demand for the development of unconventional oil and gas resources such as shale gas, hydraulic fracturing technology has become a key means to improve the reservoir conductivity. As the core material of the fracturing process, the performance of the proppant directly affects the fracture maintenance effect and gas seepage efficiency. However, there are still the following prominent problems in the application of existing proppants: Although traditional proppants such as bauxite-based ceramsite have relatively high compressive strength (for example, the crushing rate is <10% under a closing pressure of 69 MPa), their bulk density is generally on the high side (1.65 - 1.8 g / cm 3 ), resulting in too fast sedimentation speed in the fracturing fluid. High-density particles are prone to accumulate at the bottom of the fracture, causing uneven distribution of the proppant and even blocking the effective seepage channels, significantly reducing the conductivity and unable to achieve unidirectional permeability. For example, proppants with a wide particle size distribution can improve the packing permeability, but lack the design of a directional pore structure and cannot optimize the unidirectional seepage, resulting in blocked CH4 diffusion paths.

[0003] In summary, there are significant shortcomings in the existing proppants in terms of the coordinated optimization of density-strength-conductivity, resource sustainability, and process environmental protection. There is an urgent need to develop a new type of proppant with light weight, high strength, and unidirectional permeability structure. Through material design and preparation process innovation, the stable suspension of particles in the fracturing fluid, efficient support of the fracture space, and directional optimization of the CH4 seepage path can be achieved. Summary of the Invention

[0004] In view of this, the present invention provides a ceramic particle proppant with a porous unidirectional permeability structure for hydraulic fracturing and a preparation method thereof. Its purpose is to solve the problem of precipitation of proppant particles in the fracturing fluid during the hydraulic fracturing of shale gas exploitation; another purpose is to solve the problem that proppant particles block the fracture and affect CH4 seepage.

[0005] In order to achieve the above invention purposes, the present invention provides the following technical solutions:

[0006] The present invention provides a ceramic particle proppant with a porous unidirectional permeability structure for hydraulic fracturing, comprising the following raw materials in parts by weight:

[0007] 40 - 50 parts of kaolin, 15 - 25 parts of spherical metallic zinc particles, 1 - 2 parts of polyvinyl alcohol, 1 - 2 parts of carboxymethyl cellulose, 5 - 15 parts of nano - sized SiC, 1 - 3 parts of flux MoO3, 0.5 - 1.5 parts of graphene / PDMS composite material, 10 - 15 parts of hollow glass microspheres, 0.1 - 1 part of fluorosilane, 1 - 2 parts of nano - SiO2, 3 - 7 parts of aluminum silicate fiber.

[0008] Further, the particle size of the nano - sized SiC is 10 - 50 nm.

[0009] Further, the particle size of the spherical metallic zinc particles is 50 - 100 nm.

[0010] Further, the diameter of the hollow glass microspheres is 30 - 80 μm.

[0011] Further, the particle size of the nano - SiO2 is 10 - 50 nm.

[0012] The present invention provides a preparation method of the above - mentioned ceramic particle proppant with a porous single - permeable structure for hydraulic fracturing, including the following steps:

[0013] S1. Mix kaolin, nano - sized SiC, aluminum silicate fiber, flux MoO3 and spherical metallic zinc particles to obtain a dry powder mixture;

[0014] S2. Dissolve carboxymethyl cellulose and polyvinyl alcohol in water respectively to obtain a CMC solution and a PVA solution;

[0015] S3. Mix the dry powder mixture, the CMC solution and the PVA solution and then perform spray granulation to obtain particle products, and mix the particle products with hollow glass microspheres to obtain a mixture;

[0016] S4. Load the mixture into a ceramic particle mold and sequentially perform pre - pressing and cold isostatic pressing to obtain a dense green compact block;

[0017] S5. Sequentially perform sintering, crushing and screening on the dense green compact block to obtain a crude product;

[0018] S6. Immerse the crude product in a n - hexane solution of polydimethylsiloxane for vacuum - assisted impregnation, and then perform curing treatment to complete the surface hydrophobic coating; then perform the first heat treatment on the crude product in fluorosilane vapor to form a chemically - bonded hydrophobic layer and complete the deposition of the fluorosilane coupling agent; disperse nano - SiO2 in ethanol and spray it on the surface of the crude product for the second heat treatment to obtain the ceramic particle proppant with a porous single - permeable structure for hydraulic fracturing.

[0019] Further, in the step S2, the mass concentrations of the CMC solution and the PVA solution are both 1-10%; in the step S3, the temperature of spray granulation is 80-200 °C.

[0020] Further, in the step S4, the pressure of pre-pressing is 40-60 MPa and the time is 1-3 min; the pressure of cold isostatic pressing treatment is 180-220 MPa and the time is 8-12 min.

[0021] Further, in the step S5, the sintering treatment is divided into three stages. The temperature of the first stage is 450-550 °C and the heat preservation time is 1-3 h; the temperature of the second stage is 750-850 °C and the heat preservation time is 0.5-1.5 h; the temperature of the third stage is 1100-1200 °C and the heat preservation time is 2-4 h.

[0022] Further, in the step S6, the vacuum degree of vacuum-assisted impregnation is -0.1 to -0.2 MPa and the time is 20-40 min; the temperature of the curing treatment is 60-100 °C and the time is 1-3 h; the temperature of the first heat treatment is 120-180 °C and the time is 1-3 h; the temperature of the second heat treatment is 280-320 °C and the time is 40-80 min.

[0023] As can be seen from the above technical solutions, compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. In the present invention, after calcination, kaolinite mainly generates components such as mullite and aluminosilicate spinel. Carboxymethyl cellulose can enhance the cross-linking effect between particles and form hydrogen bonds between the polymer materials on the particle surface, improving the strength of the ceramic. During the firing process, metallic zinc powder will volatilize to form pores under a protective atmosphere, forming pores inside the ceramic and increasing the porosity of the ceramic. By controlling the particle size and content of metallic zinc particles, the pore size of the ceramic material is controlled to meet the requirement that the pores of the ceramic material can permeate CH4 gas while the fracturing fluid cannot permeate, realizing the suspension of the porous single-permeable ceramic proppant in the fracturing fluid, enhancing the air permeability of the ceramic proppant in the rock pores, and realizing the stable high production of shale gas.

[0025] 2. The present invention uses superhydrophobic surface modification of ceramic particles at a specific pore size of the ceramic particles to obtain lightweight water-blocking and methane-permeable porous particles. The porous ceramic particle proppant has a low density and can be suspended in the fracturing fluid. Its pores can permeate "CH4" gas while "fracturing fluid" cannot permeate, realizing the functions of particle suspension and permeability enhancement. Description of the Drawings

[0026] Figure 1Formal structure diagram of the ceramic particle proppant with a porous unidirectional permeable structure for hydraulic fracturing provided by the present invention, including surface pores, ceramic particle cross-section, ceramic particle surface, metal zinc particle pores, CH4 seepage channels, ceramic matrix, hollow glass microspheres;

[0027] Figure 2 Schematic diagram of the application of the ceramic particle proppant with a porous unidirectional permeable structure for hydraulic fracturing provided by the present invention in the process of shale gas exploitation;

[0028] Figure 3 Physical diagram of the ceramic particle proppant with a porous unidirectional permeable structure for hydraulic fracturing provided by the present invention. Detailed implementation manner

[0029] The present invention provides a ceramic particle proppant with a porous unidirectional permeable structure for hydraulic fracturing, comprising raw materials in the following parts by weight:

[0030] 40 - 50 parts of kaolin, 15 - 25 parts of spherical metal zinc particles, 1 - 2 parts of polyvinyl alcohol, 1 - 2 parts of carboxymethyl cellulose, 5 - 15 parts of nanoscale SiC, 1 - 3 parts of flux MoO3, 0.5 - 1.5 parts of graphene / PDMS composite material, 10 - 15 parts of hollow glass microspheres, 0.1 - 1 part of fluorosilane, 1 - 2 parts of nano-SiO2, 3 - 7 parts of aluminum silicate fiber.

[0031] In the present invention, the dosage of the raw materials is preferably as follows: 45 parts of kaolin, 20 parts of spherical metal zinc particles, 1.5 parts of polyvinyl alcohol, 1.5 parts of carboxymethyl cellulose, 10 parts of nanoscale SiC, 2 parts of flux MoO3, 1 part of graphene / PDMS composite material, 12 parts of hollow glass microspheres, 0.5 part of fluorosilane, 1.5 parts of nano-SiO2, 5 parts of aluminum silicate fiber.

[0032] In the present invention, the particle size of the nanoscale SiC is 10 - 50 nm. The nano-SiC particles can not only hinder crack propagation, extend the fracture path, but also form strong chemical bonds (Si - O - Si) with the matrix (mullite), improving the interface strength.

[0033] In the present invention, the particle size of the spherical metal zinc particles is 50 - 100 nm. During the firing process of the porous particles, the particles are jointly affected by the high-temperature shrinkage of the ceramic matrix, the densification of the flux, the high surface energy effect and the particle distribution limitation, and the final pore diameter is reduced to 0.35 - 0.4 nm, and the porosity is 45 - 50%, so as to realize the circulation of CH4 molecules (diameter 0.38 nm).

[0034] In the present invention, the diameter of the hollow glass microspheres is 30 - 80 μm, D90 / D10 < 1.5, the wall thickness is 2 μm, and the density is 0.6 g / cm3 , made of borosilicate material, with a softening point > 1200 °C.

[0035] In the present invention, the particle size of the nano-SiO₂ is 10 - 50 nm, and its functions are as follows: 1. Filling microcracks: During the sintering process, nano-SiO₂ migrates into the microcracks (<100 nm) of the matrix (mullite), fills the voids through surface diffusion and liquid-phase wetting, and reduces stress concentration points. 2. Promoting densification: SiO₂ reacts with Al₂O₃ in the matrix to form a low-melting glass phase (such as Al-Si-O), fills the grain boundary gaps, and further improves the material density.

[0036] In the present invention, carboxymethyl cellulose (CMC) is used as a binder to assist in forming and improve the green body strength. Its main function is to adsorb on the particle surface through hydrogen bonds and van der Waals forces to form a three-dimensional network structure, preventing drying cracks. Carboxymethyl cellulose (CMC) decomposes into CO₂ and H₂O at high temperatures, and a relatively low usage amount avoids the residual carbon from high-temperature decomposition blocking the pores; Polyvinyl alcohol (PVA) is used as a binder / plasticizer. The polymer chains entangle the particles, reduce the viscosity of the slurry, improve the fluidity and formability of the slurry, and facilitate injection molding or dry pressing. Polyvinyl alcohol (PVA) decomposes into CO₂ and H₂O at high temperatures, and a relatively low usage amount avoids the residual carbon from high-temperature decomposition blocking the pores.

[0037] In the present invention, the melting point of the flux MoO₃ is 795 °C, and it will melt at the liquid-phase sintering temperature of 1150 °C. It fills the matrix gaps through capillary action, promotes particle sliding and rearrangement, increases the density, and improves the material strength; MoO₃ forms a eutectic mixture with SiO₃ or Al₂O₃ in the matrix, further reducing the system melting point; The liquid phase of MoO₃ has a moderate viscosity at 1150 °C, buffers the thermal stress, and prevents the hollow glass microspheres (softening point > 1200 °C) from cracking.

[0038] In the present invention, aluminosilicate fibers are randomly distributed and intertwined to form a three-dimensional fiber skeleton, forming a three-dimensional network support to inhibit the shrinkage and deformation of the matrix.

[0039] The present invention provides a preparation method of the above-mentioned ceramic particle proppant with a porous single-permeable structure for hydraulic fracturing, including the following steps:

[0040] S1. Mix kaolin, nano-SiC, aluminosilicate fibers, the flux MoO₃, and spherical metal zinc particles to obtain a dry powder mixture;

[0041] S2. Dissolve carboxymethyl cellulose and polyvinyl alcohol in water respectively to obtain a CMC solution and a PVA solution;

[0042] S3. Mix the dry powder mixture, the CMC solution and the PVA solution, and then perform spray granulation to obtain granular products. Mix the granular products with hollow glass microspheres to obtain a mixture.

[0043] S4. Load the mixture into a ceramic particle mold and sequentially perform pre-pressing and cold isostatic pressing to obtain a dense green compact.

[0044] S5. Sequentially perform sintering, crushing and screening on the dense green compact to obtain a crude product.

[0045] S6. Immerse the crude product in a n-hexane solution of polydimethylsiloxane for vacuum-assisted impregnation, and then perform curing treatment to complete the surface hydrophobic coating. Then, perform the first heat treatment on the crude product in fluoro-silane vapor to form a chemically bonded hydrophobic layer and complete the deposition of the fluoro-silane coupling agent. Disperse nano-SiO2 in ethanol and spray it on the surface of the crude product for the second heat treatment to obtain the ceramic particle proppant with a porous single-permeable structure for hydraulic fracturing.

[0046] In the present invention, it also includes the pretreatment of raw materials. Mix nano-SiC (10%) with an ethanol medium (solid-liquid ratio 1:5), add 0.5% polyethylene glycol (PEG) dispersant, and ball mill for 6 hours (rotation speed 300 rpm, zirconia ball diameter 3 mm) to reduce agglomeration. After ball milling, transfer it to an ultrasonic processor (500 W, frequency 20 kHz) and process for 1 hour to further disperse the nano-particles. Cut the aluminosilicate fiber (5%) to an aspect ratio of 40 (length 200 μm, diameter 5 μm), then soak it in 5% dilute hydrochloric acid for 30 minutes and thoroughly rinse it with deionized water to remove surface impurities, ensuring no acidic residue on the surface of the aluminosilicate fiber and enhancing the bonding force with the matrix. Adopt air classification technology to select borosilicate microspheres with a diameter of 30 - 80 μm and a wall thickness of 2 μm (softening point > 1200 °C), immerse them in 10% HNO3 solution for 10 minutes, and after cleaning and drying, set aside for use.

[0047] Among them, the dispersion reaction of nano-SiC is:

[0048] SiC surface + PEG → SiC-PEG physical adsorption layer (preventing agglomeration)

[0049] (The hydroxyl group of PEG binds to the SiC surface through hydrogen bonds, improving the dispersibility)

[0050] The pickling treatment reaction of aluminosilicate fiber is:

[0051] Al-Si-O fiber + HCl → surface hydroxylation + Cl -

[0052] (Enhancing the interfacial bonding force between the fiber and the matrix and reducing sintering defects)

[0053] The hydroxylation pretreatment reaction of borosilicate microspheres is as follows:

[0054] The acid-base neutralization reaction of borosilicate glass (the composition is mainly SiO-B2O3, containing a small amount of impurities such as Na2O and CaO) with nitric acid is as follows:

[0055] Na2O + 2HNO3 → 2NaNO3 + H2O

[0056] CaO + 2HNO3 → Ca(NO3)2 + H2O

[0057] Remove the residual metal oxide impurities on the surface (such as Na + , Ca 2+ ), reduce the interface defects caused by impurity migration during the sintering process; expose SiO2 and B2O3 in the glass network and enhance the surface activity.

[0058] After nitric acid treatment, silanol groups (-Si-OH) and boranol groups (-B-OH) are formed on the glass surface through proton exchange:

[0059] ≡Si-O- + H + →≡Si-OH

[0060] ≡B-O- + H + →≡B-OH

[0061] Increase the surface hydroxyl density, improve the chemical bonding ability with matrix materials (such as kaolin and binder), and provide active sites for the subsequent deposition of fluorosilane coupling agent (to form Si-O-Si bonds).

[0062] In the present invention, in the step S2, the mass concentrations of the CMC solution and the PVA solution are both 1-10%, preferably 5%; in the step S3, the temperature of spray granulation is 80-200°C.

[0063] In the present invention, in the step S4, the pressure of pre-press forming is 40-60 MPa, preferably 50 MPa, the time is 1-3 min, preferably 2 min; the pressure of cold isostatic pressing treatment is 180-220 MPa, preferably 200 MPa, and the time is 8-12 min, preferably 10 min.

[0064] In the present invention, in the step S5, the sintering treatment is divided into three stages. The temperature of the first stage is 450-550°C, and the holding time is 1-3 h; the temperature of the second stage is 750-850°C, and the holding time is 0.5-1.5 h; the temperature of the third stage is 1100-1200°C, and the holding time is 2-4 h; the heating rate of each stage is preferably 1-5°C / min;

[0065] The reaction in the first stage is a dehydration reaction:

[0066] Al2Si2O5(OH)4 (kaolin) → Al2Si2O7 + 2H2O

[0067] Zn (solid state) → Zn (gaseous state) (fully volatilized)

[0068] The reaction in the second stage is the formation of mullite:

[0069] 3Al2Si2O7 → 2Al6Si2O 13 (mullite) + SiO2

[0070] The reaction in the third stage is the formation of the MoO3 liquid phase:

[0071] Fiber surface + Al2O3 (matrix) → Al - O - Si bond (enhanced bonding force).

[0072] In the present invention, in the step S6, the degree of vacuum for vacuum - assisted impregnation is - 0.1 to - 0.2 MPa, and the time is 20 to 40 min; the temperature for the curing treatment is 60 to 100 °C, preferably 80 °C, and the time is 1 to 3 h, preferably 2 h; the temperature for the first heat treatment is 120 to 180 °C, preferably 160 °C, and the time is 1 to 3 h, preferably 2 h; the temperature for the second heat treatment is 280 to 320 °C, preferably 300 °C, and the time is 40 to 80 min, preferably 60 min;

[0073] Among them, the curing reaction is:

[0074] Si - O - CH3 (PDMS precursor) + H2O → Si - O - Si (cross - linked network) + CH3OH

[0075] Filling macropores > 10 μm, contact angle > 150°, water - blocking and CH4 - permeable.

[0076] The deposition reaction of the fluorosilane coupling agent is:

[0077] CF3(CF2) n SiCl3 + surface - OH → CF3(CF2) n Si - O - matrix + HCl

[0078] Forming a chemically - bonded hydrophobic layer to enhance durability.

[0079] The sol - gel reaction for nano - SiO2 to fill micro - cracks is:

[0080] Si(OC2H5)4 + H2O → SiO2 (gel) + C2H5OH

[0081] Filling sintered micro - cracks, enhancing the compressive strength by + 5 MPa.

[0082] The technical principle applied in the present invention is as follows: under a protective atmosphere, zinc particles directly sublime / evaporate, leaving cavities; by controlling the size and content of metallic zinc particles, the pore size of the ceramic material is controlled, so that when the ceramic particles are under a specific pore size, their superhydrophobic surface is modified to obtain lightweight water-blocking and methane-permeable porous particles, achieving the single-permeability effect. While generating a certain buoyancy, it also meets the requirements of CH4 seepage.

[0083] Figure 2 It is a schematic diagram of the application of a ceramic particle proppant with a porous single-permeability structure in the process of shale gas exploitation. It can be seen that the advantage of achieving single-permeability for fracturing fluid and CH4 gas provides more channels for the seepage of shale gas in artificial fractures, enhances the CH4 seepage rate, and meets the requirements of continuous and efficient shale gas exploitation.

[0084] The technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0085] Example 1

[0086] Raw material ratio: 45 parts of kaolin, 20 parts of spherical metallic zinc particles, 1.5 parts of polyvinyl alcohol, 1.5 parts of carboxymethyl cellulose, 10 parts of nano-SiC, 2 parts of flux MoO3, 1 part of graphene / PDMS composite material, 12 parts of hollow glass microspheres, 0.5 part of fluorosilane, 1.5 parts of nano-SiO2, 5 parts of aluminum silicate fiber.

[0087] The preparation process is as follows: Mix nano-SiC with an ethanol medium (solid-liquid ratio 1:5), add 0.5% polyethylene glycol (PEG) dispersant, and ball mill for 6 hours (rotation speed 300 rpm, zirconia ball diameter 3 mm) to reduce agglomeration. After ball milling, transfer it to an ultrasonic processor (500 W, frequency 20 kHz) and process for 1 hour to further disperse the nano-particles; Cut the aluminum silicate fiber to an aspect ratio of 40 (length 200 μm, diameter 5 μm), then soak it in 5% dilute hydrochloric acid for 30 minutes and thoroughly rinse it with deionized water to remove surface impurities to ensure no acidic residue on the surface of the aluminum silicate fiber and enhance the bonding force with the matrix; Use air classification technology to select borosilicate microspheres with a diameter of 30 - 80 μm and a wall thickness of 2 μm (softening point > 1200 °C), immerse them in 10% HNO3 solution for 10 minutes, clean and dry them for standby.

[0088] Add kaolin, nano-SiC, aluminum silicate fiber, and flux MoO3 to a three-dimensional mixer and mix for 2 hours for ceramic matrix mixing; then add nano-zinc particles and continue to mix for 1 hour to ensure uniform dispersion and complete the mixing of the pore-forming agent to obtain a dry powder mixture.

[0089] Dissolve CMC in deionized water and stir at 60 °C until transparent to obtain a 5% CMC solution; dissolve PVA in deionized water, cool to room temperature after dissolving at 90 °C to obtain a 5% PVA solution.

[0090] Spray granulate the dry powder mixture and the binder solution (CMC + PVA) at a liquid-to-solid ratio of 1:4 (inlet temperature 200 °C, outlet temperature 80 °C) to form micron-sized particles with good fluidity (diameter 50 - 200 μm). After granulation, gently mix the particles with hollow glass microspheres to avoid breaking the microspheres and obtain a mixed material.

[0091] Load the mixed material into a ceramic particle mold, pre-press to 50 MPa, hold the pressure for 1 minute to complete pre-pressing and forming, then transfer it to a cold isostatic press, pressurize to 200 MPa, and hold the pressure for 10 minutes to obtain a dense green compact.

[0092] Perform sintering treatment on the dense green compact. The sintering is divided into 3 stages: 1. Low-temperature stage, under N2 protection (flow rate 5 L / min), heat to 500 °C at a heating rate of 5 °C / min, hold for 2 hours to completely volatilize zinc, form interconnected pores with a pore size of 0.35 - 0.4 nm, and avoid zinc oxidation. 2. Medium-temperature stage, heat the sample from 500 °C to 800 °C at a heating rate of 3 °C / min, hold for 1 hour to initially form a mullite phase skeleton, appropriately reduce the heating rate to avoid microsphere cracking caused by sudden temperature changes. 3. High-temperature stage, heat the sample from 800 °C to 1150 °C at a heating rate of 2 °C / min, hold for 3 hours, and the flux MoO3 promotes the formation of the liquid phase to fill microcracks. Finally, the sample is cooled in the furnace to 200 °C and then taken out to avoid cracking caused by residual stress. After sintering, mechanically crush the bulk material to the target particle size and obtain a crude product through screening and grading.

[0093] Immerse the crude product in a n-hexane solution containing 5% polydimethylsiloxane, perform vacuum-assisted impregnation (-0.1 MPa, 30 minutes) to fill macropores >10 μm, cure at 80 °C for 2 hours, and complete the surface hydrophobic coating when the contact angle >150°. Subsequently, place the material in a sealed container, inject fluorosilane vapor (heat at 150 °C for 2 hours) to form a chemically bonded hydrophobic layer and complete the deposition of the fluorosilane coupling agent. Then disperse nano-SiO2 in ethanol, spray it onto the material surface, and perform heat treatment at 300 °C for 1 hour to seal the sintering microcracks and complete the filling of microcracks with nano-SiO2.

[0094] Example 2

[0095] Raw material ratio: 44 parts of kaolin, 21 parts of spherical metallic zinc particles, 1.0 part of polyvinyl alcohol, 1.0 part of carboxymethyl cellulose, 11 parts of nanoscale SiC, 2 parts of flux MoO3, 1 part of graphene / PDMS composite material, 11 parts of hollow glass microspheres, 1.0 part of fluorosilane, 2.0 parts of nano-SiO2, 5 parts of aluminum silicate fiber.

[0096] The preparation process is the same as that of Example 1.

[0097] Example 3

[0098] Raw material ratio: 46 parts of kaolin, 19 parts of spherical metallic zinc particles, 1.5 parts of polyvinyl alcohol, 1.5 parts of carboxymethyl cellulose, 9 parts of nanoscale SiC, 3 parts of flux MoO3, 1 part of graphene / PDMS composite material, 13 parts of hollow glass microspheres, 0.5 part of fluorosilane, 1.5 parts of nano-SiO2, 4 parts of aluminum silicate fiber.

[0099] The preparation process is the same as that of Example 1.

[0100] Figure 3 This is the physical diagram of the proppant provided by the present invention. Using the Archimedes method, with anhydrous ethanol as the impregnation medium, the density of the ceramic particle proppants prepared in Examples 1 to 3 was measured to be between 1.05 and 1.15 g / cm 3 between.

[0101] Using a universal testing machine and according to the ASTM C773 standard, the compressive strength of the ceramic particle proppants prepared in Examples 1 to 3 was measured to be between 50 and 55 MPa.

[0102] The methane permeability was measured using a steady-state gas permeation instrument, and the result was a flux > 1×10 -6 mol / (m 2 ·s·Pa); for the water osmotic pressure test, it was pressurized to 10 kPa and maintained for 1 hour, and there was no osmosis phenomenon.

[0103] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A ceramic particle proppant for hydraulic fracturing with a porous single-permeable structure, characterized in that, Comprising the following raw materials in parts by weight: 40 - 50 parts of kaolin, 15 - 25 parts of spherical metallic zinc particles, 1 - 2 parts of polyvinyl alcohol, 1 - 2 parts of carboxymethyl cellulose, 5 - 15 parts of nano - sized SiC, 1 - 3 parts of flux MoO3, 0.5 - 1.5 parts of graphene / PDMS composite material, 10 - 15 parts of hollow glass microspheres, 0.1 - 1 part of fluorosilane, 1 - 2 parts of nano - sized SiO2, 3 - 7 parts of aluminosilicate fiber.

2. The lightweight porous single-permeable ceramic particle proppant for hydraulic fracturing according to claim 1, characterized in that, The particle size of the nano - sized SiC is 10 - 50 nm.

3. The lightweight porous single-permeable ceramic particle proppant for hydraulic fracturing according to claim 2, characterized in that, The particle size of the spherical metallic zinc particles is 50 - 100 nm.

4. The lightweight porous single-permeable ceramic particle proppant for hydraulic fracturing according to claim 3, characterized in that, The diameter of the hollow glass microspheres is 30 - 80 μm.

5. The lightweight porous single-permeable ceramic particle proppant for hydraulic fracturing according to claim 2, wherein The particle size of the nano - sized SiO2 is 10 - 50 nm.

6. The preparation method of the ceramic particle proppant with a porous single-permeable structure according to any one of claims 1 to 5, characterized in that, Comprising the following steps: S1. Mix kaolin, nano - sized SiC, aluminosilicate fiber, flux MoO3 and spherical metallic zinc particles to obtain a dry powder mixture; S2. Dissolve carboxymethyl cellulose and polyvinyl alcohol in water respectively to obtain CMC solution and PVA solution; S3. Mix the dry powder mixture, CMC solution and PVA solution and then carry out spray granulation to obtain granular products, and mix the granular products with hollow glass microspheres to obtain a mixture; S4. Load the mixture into a ceramic particle mold and successively carry out pre - pressing and cold isostatic pressing to obtain a dense green compact; S5. Carry out sintering treatment, crushing and screening on the dense green compact successively to obtain a crude product; S6. Immerse the crude product in a n - hexane solution of polydimethylsiloxane for vacuum - assisted impregnation, and then carry out curing treatment to complete the surface hydrophobic coating; then carry out the first heat treatment on the crude product in fluorosilane vapor to form a chemically bonded hydrophobic layer and complete the deposition of fluorosilane coupling agent; disperse nano - sized SiO2 in ethanol and spray it on the surface of the crude product for the second heat treatment to obtain a ceramic particle proppant with a porous single - permeable structure for hydraulic fracturing.

7. The preparation method of the ceramic particle proppant with a porous single-permeable structure for hydraulic fracturing according to claim 6, characterized in that, In the step S2, the mass concentrations of the CMC solution and the PVA solution are both 1 - 10%; in the step S3, the temperature of spray granulation is 80 - 200 °C.

8. The preparation method of the light porous single-permeable ceramic particle proppant for hydraulic fracturing according to claim 7, characterized in that, In the step S4, the pressure of pre - pressing is 40 - 60 MPa and the time is 1 - 3 min; the pressure of cold isostatic pressing is 180 - 220 MPa and the time is 8 - 12 min.

9. The preparation method of the lightweight porous single-permeable ceramic particle proppant for hydraulic fracturing according to claim 8, wherein, In the step S5, the sintering treatment is divided into three stages. The temperature of the first stage is 450 - 550 °C and the holding time is 1 - 3 h; the temperature of the second stage is 750 - 850 °C and the holding time is 0.5 - 1.5 h; the temperature of the third stage is 1100 - 1200 °C and the holding time is 2 - 4 h.

10. The preparation method of the lightweight porous single-permeable ceramic particle proppant for hydraulic fracturing according to any one of claims 6 to 9, characterized in that, In the step S6, the vacuum degree of vacuum - assisted impregnation is - 0.1 - - 0.2 MPa and the time is 20 - 40 min; the temperature of the curing treatment is 60 - 100 °C and the time is 1 - 3 h; the temperature of the first heat treatment is 120 - 180 °C and the time is 1 - 3 h; the temperature of the second heat treatment is 280 - 320 °C and the time is 40 - 80 min.

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