Petroleum fracturing sand with multi-layer composite structure and preparation method thereof

Abstract

The invention discloses petroleum fracturing sand with a multi-layer composite structure and a preparation method of the petroleum fracturing sand, and belongs to the technical field of oil and gas exploitation, and the petroleum fracturing sand is prepared by adopting a three-layer composite structure of a high-strength inner core, an interface transition layer and a high-toughness shell. By means of the structural design, the product has the high compressive strength (larger than or equal to 8000 psi) of the inner core and the high toughness and low breakage rate (smaller than 3%) of the outer shell at the same time, and the long-term flow conductivity of fractured cracks is remarkably improved. The hydraulic fracturing fluid is especially suitable for hydraulic fracturing operation of unconventional reservoirs such as deep wells, ultra-deep wells and shale oil and gas.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development engineering technology, specifically relating to a petroleum fracturing sand with a multi-layered composite structure and its preparation method. Background Technology

[0002] Fracturing sand is a key material used in hydraulic fracturing technology to support fractures in underground rock formations. Its performance directly determines the conductivity of the fractures and the recovery rate of oil and gas wells. As oil and gas exploration and development shifts to deeper and tighter reservoirs, the performance requirements for fracturing sand are becoming increasingly stringent. Traditional single natural quartz sand or ceramsite proppants have significant drawbacks: natural quartz sand has relatively low strength and is easily broken in deep wells with high closure pressure, leading to a sharp decline in conductivity; while ceramsite has high strength, it has high density, high cost, and is relatively brittle.

[0003] While existing technologies employ resin coatings to improve the performance of fracturing sand, these methods are mostly limited to sand control or improved dispersion. The coatings are typically thin and functionally singular, failing to fundamentally resolve the inherent contradiction between strength and toughness. In deep-well high-pressure environments, a single rigid structure is still prone to brittle fracture, while a single flexible structure cannot effectively support the fractures.

[0004] Therefore, there is an urgent need in this field for a new type of fracturing sand that can withstand extremely high closure pressure and has excellent toughness and low fragmentation rate in order to maintain the long-term high conductivity of the fracture. Summary of the Invention

[0005] In view of the above-mentioned prior art, the purpose of this invention is to provide an oil fracturing sand with a multi-layered composite structure and its preparation method. The oil fracturing sand provided by this invention achieves both high compressive strength and high toughness through an innovative "rigid-flexible" structural design.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a fracturing sand with a multi-layered composite structure, the fracturing sand comprising: a mineral core; an interface transition layer covering the surface of the mineral core; and a modified resin-based shell covering the surface of the interface transition layer; wherein the mineral core is a solid particle formed by rapid cooling and solidification of nickel-iron alloy molten slag after water quenching or air quenching.

[0007] The term "petroleum fracturing sand" refers to a key support material used in hydraulic fracturing operations in oil and gas wells. Its main function is to fill fractures, maintain formation fracture opening, and thus improve oil and gas flow efficiency.

[0008] The interface transition layer is formed by encapsulating the surface of the mineral core with an interface transition layer solution. The preparation method of the interface transition layer solution is as follows: Weigh γ-glycidoxypropyltrimethoxysilane (KH-560), add it to anhydrous ethanol, add a few drops of glacial acetic acid (0.5-1 g), and stir until completely dissolved to obtain an interfacial transition layer solution. Preferably, the prepared interfacial transition layer solution is used within 4 hours.

[0009] The modified resin-based shell is formed by curing a modified resin-based shell coating liquid, which is a phenolic resin / alumina organic-inorganic hybrid material prepared by a sol-gel method using phenolic resin and aluminum isopropoxide. This hybrid material combines the toughness of resin with the rigidity and heat resistance of inorganic materials. The preparation method of the modified resin-based shell coating liquid is as follows: (1) Dissolve aluminum isopropoxide in anhydrous ethanol, heat in a water bath and stir until completely clear to obtain a mixed solution of aluminum isopropoxide and ethanol. Slowly add the mixed solution of aluminum isopropoxide and ethanol to the phenolic resin ethanol solution and stir to obtain component A solution. (2) Mix deionized water with concentrated nitric acid to obtain a 0.1 mol / L dilute nitric acid catalytic hydrolysis solution. Under continuous high-speed stirring, slowly add the dilute nitric acid catalytic hydrolysis solution to component A solution. The entire addition process is carried out in a water bath at 35-40℃ and is completed in 1-1.5 hours. (3) Continue stirring at a water bath temperature of 35-40℃ for 2-3 hours to obtain the modified resin-based shell coating solution. Preferably, the prepared modified resin-based shell coating solution is used within 8 hours.

[0010] The phenolic resin ethanol solution contains 60-80% phenolic resin solids by mass.

[0011] The nickel-iron alloy molten slag contains, by mass percentage, the following components: Ni 0.03-0.04%, Al2O3 3.5-4.5%, Cr2O3 1-2%, TFe 4.5-5.5%, CaO 1-2%, MgO 30-35%, SiO2 50-55%, MnO 0.5-0.7%, TiO2 0.1-0.2%, CO 0.005-0.009%, and Cu 0.001-0.0034%.

[0012] Preferably, the nickel-iron alloy molten slag contains the following components by mass percentage: Ni 0.038%, Al2O3 4.048%, Cr2O3 1.115%, TFe 4.929%, CaO 1.818%, MgO 33.188%, SiO2 52.343%, MnO 0.586%, TiO2 0.158%, CO 0.008%, and Cu 0.002%.

[0013] The mineral core may also be one of quartz sand, ceramsite, or sintered bauxite.

[0014] The mass of the interface transition layer is 0.1%-0.5% of the mass of the high-strength mineral core; the mass of the modified resin-based shell is 1.5%-4% of the mass of the high-strength mineral core.

[0015] The types of oil fracturing sand include 16 / 30 mesh, 20 / 40 mesh, 30 / 50 mesh, 40 / 70 mesh, or 70 / 140 mesh.

[0016] In a second aspect, the present invention provides a method for preparing the above-mentioned oil fracturing sand, comprising the following steps: (1) Use the solid particles formed by water quenching or air quenching of nickel-iron alloy molten slag as the mineral core, and heat the mineral core to 150-220℃; (2) Under high-speed stirring, spray the interface transition layer solution into the hot core of step (1) so that it can uniformly coat the core surface and form an interface transition layer. (3) Based on the treatment in step (2), add modified resin-based shell coating liquid to uniformly coat the surface of the mineral core that has been wrapped with the interface transition layer, so as to form a modified resin-based shell. (4) Based on the processing in step (3), the coated product is cooled to room temperature and screened to obtain oil fracturing sand of the target particle size.

[0017] In step (1), heating the high-strength mineral core to 150-220℃ is a key parameter. In a large number of preliminary experiments, when the temperature is too low (<150℃), the reaction rate between the interfacial transition layer solution and the sand grain surface is slow, and a dense interfacial transition layer cannot be formed. When the temperature is too high (>220℃), the interfacial transition layer solution will be over-coked upon contact with the sand grain surface, affecting the coupling effect and causing the sand grain to turn yellow.

[0018] In step (2), an atomizing spray gun with an aperture of 0.5-1.0 mm can be used to uniformly and finely spray the prepared interface transition layer solution onto the hot sand surface within 1-2 minutes. After spraying, continue high-speed stirring at 150-220℃ (preferably 180℃) for 5 minutes. During this process, ethanol vapor can be observed to evaporate, accompanied by a slight silane condensation odor. This period is the critical reaction window to ensure that the silane coupling agent fully reacts with the mineral core surface and completes the condensation. After the reaction in step (2) is completed, the sand particles should remain in a free-flowing, loose state without any lumps or adhesion. When the sand particles are removed, their surface color should be pure white; if they are yellow, it indicates that the preheating temperature is too high or the reaction time is too long.

[0019] In a third aspect, the present invention provides the application of the above-mentioned petroleum fracturing sand in hydraulic fracturing operations of oil and gas wells.

[0020] The term "hydraulic fracturing" refers to the injection of high-pressure fluid into the underground formation of an oil and gas well to create artificial fractures in the tight rock. Proppants are then used to maintain these fractures, thereby opening pathways for oil and gas flow and improving recovery rates. It targets tight formations, primarily used in shale, tight sandstone, and other reservoirs where oil and gas flow is difficult, allowing for the effective extraction of oil and gas resources that would otherwise be challenging to access.

[0021] The petroleum fracturing sand prepared by this invention is suitable for hydraulic fracturing operations in oil and gas wells, including deep wells and ultra-deep wells with depths exceeding 3000 meters, and for the exploitation of shale gas and tight sandstone oil and gas reservoirs. The beneficial effects of this invention are: 1. This invention pioneers a composite structure of "high-strength core - interface layer - high-toughness outer shell". The core is responsible for bearing pressure, while the outer shell is responsible for impact resistance and energy absorption. The two work together through the interface layer to achieve a balance between high strength and low breakage rate.

[0022] 2. Due to the synergistic effect of the composite structure, this product maintains high compressive strength (≥8000psi) while significantly reducing the breakage rate to below 3%, far exceeding the API standard requirements for high-quality proppant. This means that in long-term production, fractures can maintain higher conductivity, thereby increasing oil and gas production.

[0023] 3. The fracturing sand provided by this invention is particularly suitable for harsh downhole environments, such as deep wells, ultra-deep wells and shale formations. Its excellent comprehensive performance can effectively cope with the challenges brought about by formation creep and stress fluctuations, providing key material support for the economical and efficient development of unconventional oil and gas resources. Detailed Implementation

[0024] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0025] The specific embodiments of the present invention will be described in further detail below with reference to examples. The following detailed descriptions are illustrative and intended to provide further explanation of this application, rather than limiting the scope of the invention.

[0026] Example 1: Preparation of oil fracturing sand 1. Preparation of mineral cores The nickel-iron alloy molten slag produced during the nickel-iron alloy smelting process is taken. The slag temperature of the nickel-iron alloy molten slag is 1600 degrees Celsius, and the slag discharge rate is 2 tons / minute. The nickel-iron alloy molten slag contains the following components by mass percentage: Ni 0.038%, Al2O3 4.048%, Cr2O3 1.115%, TFe 4.929%, CaO 1.818%, MgO 33.188%, SiO2 52.343%, MnO 0.586%, TiO2 0.158%, CO 0.008%, and Cu 0.002%.

[0027] High-pressure water pumps (performance parameters: flow rate ≥ 1800 m³ / h, pressure ≥ 0.45 MPa, head ≥ 45 m) simultaneously spray high-speed water jets on both sides of the molten slag outlet to impact and rapidly cool the molten slag. Under hydraulic action, the molten slag is pulverized and instantly cooled, solidifying into solid particles of varying sizes. 20 / 40 mesh solid particles are then screened as mineral nuclei.

[0028] 2. Preparation of interfacial transition layer solution Accurately weigh 20 g (0.2% of the core mass) of γ-glycidoxypropyltrimethoxysilane (KH-560). Add the weighed γ-glycidoxypropyltrimethoxysilane to 980 g of anhydrous ethanol, add 0.5 g of glacial acetic acid dropwise, and stir with a glass rod until completely dissolved to prepare a 2.0 wt% interfacial transition layer solution.

[0029] 3. Preparation of modified resin-based shell coating liquid (1) Dissolve 120.2 g of aluminum isopropoxide in 480.8 g of anhydrous ethanol, heat in a water bath at 40 °C and stir until completely clear to obtain a 20 wt% aluminum isopropoxide and ethanol mixed solution. Under mechanical stirring at 500 rpm, slowly add the 20 wt% aluminum isopropoxide and ethanol mixed solution dropwise to 200.0 g (2% of the core mass) of thermosetting phenolic resin ethanol solution with a solid content of 70% (of which the solid mass of phenolic resin is 140.0 g). After the addition is complete, continue stirring for 30 minutes to obtain component A solution; (2) Mix deionized water with concentrated nitric acid to obtain a 0.1 mol / L dilute nitric acid catalytic hydrolysis solution. Under continuous high-speed stirring at 500 rpm, slowly add the dilute nitric acid catalytic hydrolysis solution to component A solution. The entire addition process is carried out in a water bath at 40℃ and is completed within 1 hour. (3) Continue stirring at 40℃ water bath temperature for 2.5 hours. At this time, the solution remains uniform and transparent or opalescent, indicating that a stable pre-hybridized sol has been formed, and the modified resin-based shell coating liquid is obtained.

[0030] 4. Preparation of petroleum fracturing sand (1) Weigh 10 kg of mineral core, then heat it to 180°C and keep it there for 1 hour to fully dry and activate the surface; (2) Spray all the prepared interfacial transition layer solution continuously and evenly onto the mineral core under high-speed stirring at 180°C and 800 rpm using a spray gun. After all the interfacial transition layer solution has been sprayed, keep the temperature at 180°C and continue stirring for 15 minutes to ensure full solidification and formation of the interfacial transition layer.

[0031] (3) Based on the treatment in step (2), spray all the modified resin-based shell coating liquid continuously and evenly onto the mineral core that coats the interface transition layer under high-speed stirring at 180°C and 800 rpm using a spray gun. After all the coating liquid has been sprayed, keep the temperature at 180°C and continue stirring for 15 minutes to ensure full curing and form the modified resin-based shell.

[0032] (4) Based on the processing in step (3), the coated product is cooled to room temperature and then screened through a 20 / 40 mesh standard sieve to obtain oil fracturing sand of the target particle size.

[0033] Example 2: Preparation of oil fracturing sand In this embodiment, the mineral core is made of quartz sand.

[0034] 1. Preparation of interfacial transition layer solution Accurately weigh 10 g (0.1% of the core mass) of γ-glycidoxypropyltrimethoxysilane (KH-560). Add the weighed γ-glycidoxypropyltrimethoxysilane to 490 g of anhydrous ethanol, add 0.25 g of glacial acetic acid dropwise, and stir with a glass rod until completely dissolved to prepare a 2.0 wt% interfacial transition layer solution.

[0035] 2. Preparation of modified resin-based shell coating liquid (1) Dissolve 126.2 g of aluminum isopropoxide in 504.8 g of anhydrous ethanol, heat in a water bath at 40 °C and stir until completely clear to obtain a 20 wt% aluminum isopropoxide and ethanol mixed solution. Under mechanical stirring at 500 rpm, slowly add the 20 wt% aluminum isopropoxide and ethanol mixed solution to 300.0 g (accounting for 2.1% of the core mass) of thermosetting phenolic resin ethanol solution with a solid content of 70% (of which the solid mass of phenolic resin is 210.0 g). After the addition is complete, continue stirring for 30 minutes to obtain component A solution; (2) Mix deionized water with concentrated nitric acid to obtain a 0.1 mol / L dilute nitric acid catalytic hydrolysis solution. Under continuous high-speed stirring at 500 rpm, slowly add the dilute nitric acid catalytic hydrolysis solution to component A solution. The entire addition process is carried out in a water bath at 40℃ and is completed within 1 hour. (3) Continue stirring at 40℃ water bath temperature for 2.5 hours. At this time, the solution remains uniform and transparent or opalescent, indicating that a stable pre-hybridized sol has been formed, and the modified resin-based shell coating liquid is obtained.

[0036] 3. Preparation of petroleum fracturing sand (1) Weigh 10 kg of 20 / 40 mesh quartz sand core, clean and dry it, then heat it to 190°C and keep it for 1 hour to fully dry and activate the surface; (2) Spray all the prepared interfacial transition layer solution continuously and evenly onto the quartz sand core under high-speed stirring at 190°C and 800 rpm using a spray gun. After all the interfacial transition layer solution has been sprayed, keep the temperature at 190°C and continue stirring for 15 minutes to ensure full curing and formation of the interfacial transition layer.

[0037] (3) Based on the treatment in step (2), spray all the modified resin-based shell coating liquid continuously and evenly onto the quartz sand coating the interface transition layer under high-speed stirring at 190°C and 800 rpm using a spray gun. After all the coating liquid has been sprayed, keep the temperature at 190°C and continue stirring for 15 minutes to ensure full curing and form the modified resin-based shell.

[0038] (4) Based on the processing in step (3), the coated product is cooled to room temperature and then screened through a 20 / 40 mesh standard sieve to obtain oil fracturing sand of the target particle size.

[0039] Comparative Example 1: Preparation of Petroleum Fracturing Sand The difference between the preparation methods of Comparative Example 1 and Example 1 lies in that the modified resin-based shell is not formed by the coating liquid without a modified resin-based shell. The specific preparation method is as follows: 1. Preparation of mineral cores Same as Example 1.

[0040] 2. Preparation of interfacial transition layer solution Accurately weigh 20 g (0.2% of the core mass) of γ-glycidoxypropyltrimethoxysilane (KH-560). Add the weighed γ-glycidoxypropyltrimethoxysilane to 980 g of anhydrous ethanol, add 0.5 g of glacial acetic acid dropwise, and stir with a glass rod until completely dissolved to prepare a 2.0 wt% interfacial transition layer solution.

[0041] 3. Preparation of petroleum fracturing sand (1) Weigh 10 kg of mineral core, heat to 180°C and keep for 1 hour to fully dry and activate the surface; (2) Spray all the prepared interfacial transition layer solution continuously and evenly onto the mineral core under high-speed stirring at 180°C and 800 rpm using a spray gun. After all the interfacial transition layer solution has been sprayed, keep the temperature at 180°C and continue stirring for 15 minutes to ensure full solidification and formation of the interfacial transition layer.

[0042] (3) Based on the processing in step (2), the coated product is cooled to room temperature and then screened through a 20 / 40 mesh standard sieve to obtain oil fracturing sand of the target particle size.

[0043] Comparative Example 2: Preparation of Petroleum Fracturing Sand The difference between the preparation methods of Comparative Example 2 and Example 1 is that the solution without an interface transition layer forms an interface transition layer. The specific preparation method is as follows: 1. Preparation of mineral cores Same as Example 1.

[0044] 2. Preparation of modified resin-based shell coating liquid (1) Dissolve 120.2 g of aluminum isopropoxide in 480.8 g of anhydrous ethanol, heat in a water bath at 40 °C and stir until completely clear to obtain a 20 wt% aluminum isopropoxide and ethanol mixed solution. Under mechanical stirring at 500 rpm, slowly add the 20 wt% aluminum isopropoxide and ethanol mixed solution dropwise to 200.0 g (2% of the core mass) of thermosetting phenolic resin ethanol solution with a solid content of 70% (of which the solid mass of phenolic resin is 140.0 g). After the addition is complete, continue stirring for 30 minutes to obtain component A solution; (2) Mix deionized water with concentrated nitric acid to obtain a 0.1 mol / L dilute nitric acid catalytic hydrolysis solution. Under continuous high-speed stirring at 500 rpm, slowly add the dilute nitric acid catalytic hydrolysis solution to component A solution. The entire addition process is carried out in a water bath at 40℃ and is completed in 1 hour. (3) Continue stirring at 40℃ water bath temperature for 2.5 hours. At this time, the solution remains uniform and transparent or opalescent, indicating that a stable pre-hybridized sol has been formed, and the modified resin-based shell coating liquid is obtained.

[0045] 3. Preparation of petroleum fracturing sand (1) Weigh 10 kg of mineral core, then heat it to 180°C and keep it there for 1 hour to fully dry and activate the surface; (2) Spray all the modified resin-based shell coating liquid continuously and evenly onto the mineral core under high-speed stirring at 180°C and 800 rpm using a spray gun. After all the coating liquid has been sprayed, keep the temperature at 180°C and continue stirring for 15 minutes to ensure full curing and formation of the modified resin-based shell.

[0046] (3) Based on the processing in step (2), the coated product is cooled to room temperature and then screened through a 20 / 40 mesh standard sieve to obtain oil fracturing sand of the target particle size.

[0047] Experimental Example: Performance Testing A 20 / 40 mesh mineral core prepared in Example 1, which was neither coated with an interfacial transition layer solution to form an interfacial transition layer nor coated with a modified resin-based shell coating liquid to form a modified resin-based shell, was used as a control group. The petroleum fracturing sands prepared in the control group, Example 1, Comparative Example 1, and Comparative Example 2 were tested for compressive strength, conductivity, and fragmentation rate according to API RP 19C standards at a closure pressure of 69 MPa. The results are shown in Table 1. Table 1: Performance Measurement The test results show that the fracturing sand provided by this invention (Example 1) is significantly superior to the comparative example in terms of compressive strength, fracturing rate, and key indicator conductivity. The uncoated mineral core has the lowest conductivity. Coating only with an interface transition layer produces a slight reinforcing effect, but the improvement is not significant. Coating only with a modified resin-based shell provides the main compressive and fracturing resistance, but due to weak interfacial bonding, the shell is easily peeled or detached from the smooth mineral core surface under extremely high pressure, limiting the upper limit of performance. When both an interface transition layer and a modified resin-based shell are coated, the interface transition layer avoids interfacial peeling caused by stress concentration, and the hard, rigid modified resin-based shell provides highly efficient compressive and fracturing resistance. The two work synergistically, producing a synergistic effect and maximizing performance.

[0048] The above description is merely a preferred embodiment of this application and is not intended to limit the application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications made within the spirit and principles of this application are not permitted. Equivalent substitutions and improvements should all be included within the scope of protection of this application.

Claims

1. A petroleum fracturing sand with a multi-layered composite structure, characterized in that, The oil fracturing sand comprises: a mineral core; an interface transition layer covering the surface of the mineral core; and a modified resin-based shell covering the surface of the interface transition layer; wherein the mineral core is a solid particle formed by rapid cooling and solidification of nickel-iron alloy molten slag after water quenching or air quenching.

2. The fracturing sand according to claim 1, characterized in that, The interface transition layer is formed by encapsulating the surface of the mineral core with an interface transition layer solution. The preparation method of the interface transition layer solution is as follows: Weigh out γ-glycidoxypropyltrimethoxysilane, add it to anhydrous ethanol, add a few drops of glacial acetic acid, and stir until completely dissolved to obtain an interfacial transition layer solution.

3. The oil fracturing sand according to claim 1, characterized in that, The modified resin-based shell is formed by curing a modified resin-based shell coating liquid, and the preparation method of the modified resin-based shell coating liquid is as follows: (1) Dissolve aluminum isopropoxide in anhydrous ethanol, heat in a water bath and stir until completely clear to obtain a mixed solution of aluminum isopropoxide and ethanol. Slowly add the mixed solution of aluminum isopropoxide and ethanol to the phenolic resin ethanol solution and stir to obtain component A solution. (2) Mix deionized water with concentrated nitric acid to obtain a 0.1 mol / L dilute nitric acid catalytic hydrolysis solution. Under continuous high-speed stirring, slowly add the dilute nitric acid catalytic hydrolysis solution to component A solution. The entire addition process is carried out in a water bath at 35-40℃ and is completed in 1-1.5 hours. (3) Continue stirring at a water bath temperature of 35-40℃ for 2-3 hours to obtain the modified resin-based shell coating liquid.

4. The oil fracturing sand according to claim 3, characterized in that, The phenolic resin ethanol solution contains 60-80% phenolic resin solids by mass.

5. The oil fracturing sand according to claim 1, characterized in that, The nickel-iron alloy molten slag contains, by mass percentage, the following components: Ni 0.03-0.04%, Al2O3 3.5-4.5%, Cr2O3 1-2%, TFe 4.5-5.5%, CaO 1-2%, MgO 30-35%, SiO2 50-55%, MnO 0.5-0.7%, TiO2 0.1-0.2%, CO 0.005-0.009%, and Cu 0.001-0.0034%.

6. The oil fracturing sand according to claim 1, characterized in that, The mass of the interface transition layer is 0.1%–0.5% of the mass of the mineral core; the mass of the modified resin-based shell is 1.5%–4% of the mass of the high-strength mineral core.

7. The petroleum fracturing sand according to any one of claims 1-6, characterized in that, The types of oil fracturing sand include: 16 / 30 mesh, 20 / 40 mesh, 30 / 50 mesh, 40 / 70 mesh, or 70 / 140 mesh.

8. The method for preparing petroleum fracturing sand according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Use the solid particles formed by water quenching or air quenching of nickel-iron alloy molten slag as the mineral core, and heat the mineral core to 150-220℃; (2) Under high-speed stirring, the interface transition layer solution of claim 2 is sprayed into the mineral core of step (1) so that it uniformly coats the core surface and forms an interface transition layer. (3) Based on the treatment in step (2), the modified resin-based shell coating liquid of claim 3 is added to make the modified resin-based shell coating liquid uniformly coated on the surface of the mineral core that has been wrapped with the interface transition layer to form a modified resin-based shell. (4) Based on the processing in step (3), the coated product is cooled to room temperature and screened to obtain oil fracturing sand of the target particle size.

9. The application of the petroleum fracturing sand according to any one of claims 1-7 in hydraulic fracturing operations of oil and gas wells.

10. The application according to claim 9, characterized in that, The aforementioned petroleum fracturing sand is applicable to deep wells and ultra-deep wells with depths exceeding 3000 meters, as well as the exploitation of shale gas and tight sandstone oil and gas reservoirs, in hydraulic fracturing operations of oil and gas wells.

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