High-strength environment-friendly ceramic grain fracture proppant

Abstract

The application discloses a high-strength environment-friendly ceramsite fracture proppant, and the high-strength environment-friendly ceramsite fracture proppant is formed through chemical reaction and physical complementation among components, and a multi-level and fully-functional composite network structure is formed.The structure not only significantly improves the mechanical strength, corrosion resistance and conductivity of the material, but also realizes efficient utilization of resources and sustainable protection of the environment by utilizing industrial waste and renewable resources.The synergistic effect of the components at the molecular level makes the composite proppant find a perfect balance between high performance and environmental protection, meets multiple requirements of modern industry for efficient and environmentally-friendly materials, and has wide application prospect and significant market competitiveness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil exploitation, in particular to a high-strength environment-friendly ceramsite fracture proppant and a preparation method thereof. BACKGROUND

[0002] In modern oil exploitation processes, proppants, as key materials in hydraulic fracturing technology, play an important role in maintaining and supporting fracture cracks and ensuring smooth flow of oil and gas. Traditional proppants mainly use silica sand, ceramic particles and synthetic polymer materials. These materials are widely used in oil and gas exploitation operations under various geological conditions due to their excellent mechanical strength and stability. However, with the increasing awareness of environmental protection and the popularization of sustainable development concept, the environmental problems caused by traditional proppants in production, use and disposal are increasingly prominent. The exploitation of silica sand not only consumes a large amount of water resources and energy, but also causes damage to the ecological system, such as land degradation and destruction of biological habitats. In addition, the transportation process of silica sand involves high energy consumption and large carbon emissions, further aggravating the environmental burden. Although ceramic proppants have improved mechanical properties, their production process is complex and costly, making it difficult to achieve large-scale application. At the same time, synthetic polymer materials have shortcomings in environmental friendliness and cannot meet the increasingly stringent environmental requirements.

[0003] Under this background, the development of high-strength environment-friendly ceramsite fracture proppants with high strength and environmental friendliness has become a technical problem that needs to be solved in the field of material science. Environment-friendly proppants not only need to be comparable to traditional proppants in mechanical properties, but also need to surpass them in some aspects to meet the harsh requirements of high pressure and high temperature complex geological conditions, and need to realize environmental protection in material selection and preparation process. SUMMARY

[0004] To solve or partially solve the problems in the related art, the present application provides a high-strength environment-friendly ceramsite fracture proppant, which comprises the following components by weight fraction:

[0005] 57-63 parts of surface silane-modified fly ash;

[0006] 28-32 parts of surface-activated quartz sand;

[0007] 4-6 parts of surface-modified basalt fiber;

[0008] 2-4 parts of surface-carboxylated graphene nanoplatelets;

[0009] 1.5-2.5 parts of surface-carboxylated carbon nanotubes;

[0010] 1.5-2.5 parts of bio-based polyurethane with NCO and OH functional groups;

[0011] 0.8-1.2 parts of aluminum polyphosphate anti-corrosion agent;

[0012] 0.8-1.2 parts polyethylene glycol lubricant.

[0013] Furthermore, the preparation method of the surface silanized fly ash includes:

[0014] The particle size is 20-45μm and the specific surface area is 350-450m 2 / g of fly ash is vacuum dried at 80-100°C for 4-6 hours;

[0015] Disperse the dried fly ash in anhydrous ethanol, add 3-5wt% of silane coupling agent KH550, and stir the mixture at 60-70°C for 2-3 hours;

[0016] Filter, wash, and dry at 60-80° C. for 8-12 hours to obtain fly ash with surface silanization modification.

[0017] Furthermore, the preparation method of the surface-activated quartz sand includes:

[0018] Quartz sand with a particle size of 45-75 μm and a purity of ≥99.5% was ultrasonically cleaned with deionized water and anhydrous ethanol in sequence;

[0019] Soak the cleaned quartz sand in a 10-15wt% NaOH solution at 90-95°C for 1-2 hours;

[0020] Neutralize with dilute HCl to neutrality, wash with water and dry to obtain surface-activated quartz sand.

[0021] Furthermore, the preparation method of the surface-modified basalt fiber includes:

[0022] Basalt fiber with an aspect ratio of 100-150 is vacuum dried at 120-150°C for 2-3 hours;

[0023] The dried fiber was immersed in a 3-5wt% silane coupling agent KH560 solution and ultrasonically treated at room temperature for 30-60 minutes;

[0024] Filtering, washing, and drying at 80-100° C. for 4-6 hours to obtain surface-modified basalt fibers.

[0025] Furthermore, the preparation method of the surface carboxylated graphene nanosheets includes:

[0026] The specific surface area ≥800m 2 / g of graphene nanosheets were dispersed in a mixture of concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1);

[0027] Ultrasonic treatment at 60-70°C for 2-3 hours;

[0028] The mixture was filtered, washed with water until neutral, and vacuum dried at 60-80° C. for 12 hours to obtain surface carboxylated graphene nanosheets.

[0029] Furthermore, the method for preparing the surface carboxylated carbon nanotubes comprises:

[0030] The specific surface area ≥ 600m 2 / g of carbon nanotubes were dispersed in a mixture of concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1);

[0031] Ultrasonic treatment at 70-80°C for 3-4 hours;

[0032] The mixture was filtered, washed with water until neutral, and dried in vacuum at 80-100° C. for 12 hours to obtain surface carboxyl-grouped carbon nanotubes.

[0033] Furthermore, the preparation method of the bio-based polyurethane having NCO and OH functional groups includes:

[0034] Castor oil and polyethylene glycol are used as raw materials and mixed in a molar ratio of 1:1;

[0035] Add diisocyanate and stir the reaction at 60-70°C for 2-3 hours;

[0036] After cooling to room temperature, bio-based polyurethane with NCO and OH functional groups was obtained.

[0037] Furthermore, the particle size of the polyaluminum phosphate anti-corrosion agent is 0.5-1 μm.

[0038] Furthermore, the molecular weight of the polyethylene glycol lubricant is 2000-4000.

[0039] Furthermore, the preparation method of the composite proppant includes:

[0040] Mix the components in proportion and add 30-40% anhydrous ethanol by volume;

[0041] Mix well in a high-speed blender at a speed of 800-1000 rpm for 15-20 minutes;

[0042] The composite proppant is obtained by drying at 80-100° C. for 4-6 hours.

[0043] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention.

[0044] Beneficial technical effects of the present invention:

[0045] The high-strength environment-friendly ceramic proppant has a multi-level and fully functional composite network structure formed through chemical reaction and physical complementation between components. The structure not only significantly improves the mechanical strength, corrosion resistance and electrical conductivity of the material, but also realizes efficient use of resources and sustainable protection of the environment by using industrial waste and renewable resources. The synergistic effect of the components at the molecular level enables the composite proppant to find a perfect balance between high performance and environmental protection, meet the multiple needs of modern industry for efficient and environmentally friendly materials, and show broad application prospects and significant market competitiveness. DETAILED DESCRIPTION

[0046] Optional embodiments of the present application will be described in more detail below. Although optional embodiments of the present application are expressed, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments expressed herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0047] The terms used in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein means and includes any or all possible combinations of one or more associated listed items.

[0048] The present application provides a high-strength environment-friendly ceramic proppant, which comprises the following components by weight fraction:

[0049] 57-63 parts of surface silane-modified fly ash;

[0050] 28-32 parts of surface-activated quartz sand;

[0051] 4-6 parts of surface-modified basalt fiber;

[0052] 2-4 parts of surface carboxylated graphene nanoplatelets;

[0053] 1.5-2.5 parts of surface carboxylated carbon nanotubes;

[0054] 1.5-2.5 parts of bio-based polyurethane with NCO and OH functional groups;

[0055] 0.8-1.2 parts of polyaluminum phosphate corrosion inhibitor;

[0056] 0.8-1.2 parts of polyethylene glycol lubricant.

[0057] In one embodiment of the present invention, the method for preparing the surface silanized fly ash comprises:

[0058] The particle size is 20-45μm and the specific surface area is 350-450m 2 / g of fly ash is vacuum dried at 80-100°C for 4-6 hours;

[0059] Disperse the dried fly ash in anhydrous ethanol, add 3-5wt% of silane coupling agent KH550, and stir the mixture at 60-70°C for 2-3 hours;

[0060] Filter, wash, and dry at 60-80° C. for 8-12 hours to obtain fly ash with surface silanization modification.

[0061] In one embodiment of the present invention, the method for preparing the surface-activated quartz sand comprises:

[0062] Quartz sand with a particle size of 45-75 μm and a purity of ≥99.5% was ultrasonically cleaned with deionized water and anhydrous ethanol in sequence;

[0063] Soak the cleaned quartz sand in a 10-15wt% NaOH solution at 90-95°C for 1-2 hours;

[0064] Neutralize with dilute HCl to neutrality, wash with water and dry to obtain surface-activated quartz sand.

[0065] In one embodiment of the present invention, the preparation method of the surface-modified basalt fiber includes:

[0066] Basalt fiber with an aspect ratio of 100-150 is vacuum dried at 120-150°C for 2-3 hours;

[0067] The dried fiber was immersed in a 3-5wt% silane coupling agent KH560 solution and ultrasonically treated at room temperature for 30-60 minutes;

[0068] Filtering, washing, and drying at 80-100° C. for 4-6 hours to obtain surface-modified basalt fibers.

[0069] First, surface-silanized fly ash (57-63 parts) is treated with a silane coupling agent (such as KH550) to form silicon-oxygen bonds on its surface. This not only enhances the interfacial adhesion between the fly ash and other inorganic components (such as quartz sand and basalt fiber), but also effectively utilizes industrial waste and reduces environmental burden. Surface-activated quartz sand (28-32 parts) is treated with NaOH to increase its surface hydroxyl content, improving its chemical compatibility with the fly ash and polyurethane matrix, forming a more stable silicon-oxygen network structure, and significantly improving the mechanical strength and stability of the composite.

[0070] Surface-modified basalt fibers (4-6 parts) form covalent bonds with the NCO and OH functional groups in bio-based polyurethane (1.5-2.5 parts) through a silane coupling agent (such as KH560). This chemical bonding not only strengthens the interfacial bonding between the fiber and the matrix, but also improves the tensile and flexural properties of the material by dispersing stress. Nanoscale surface carboxylated graphene nanosheets (2-4 parts) and carbon nanotubes (1.5-2.5 parts) undergo carboxylation treatment to form more carboxyl groups that react with the functional groups in the polyurethane, promoting the uniform dispersion of the nanofillers in the matrix and significantly improving the mechanical strength, conductivity, and thermal stability of the composite material. In addition, the polyaluminum phosphate anti-corrosion agent (0.8-1.2 parts) effectively inhibits corrosion reactions by forming complexes with the metal ions in the composite material, extending the service life of the material. At the same time, its nanoscale particle size ensures the uniform distribution of the anti-corrosion effect.

[0071] The polyethylene glycol lubricant (0.8-1.2 parts) improves the fluidity and processing properties of the composite material through interaction with other components, ensuring uniform distribution of the components during high-temperature drying, and preventing stress concentration and cracking within the material. Furthermore, bio-based polyurethane, a renewable resource, contains NCO and OH functional groups in its molecular structure, which not only provide multiple cross-linking sites and enhance the stability of the overall network structure, but also reduces dependence on petroleum-based materials and reduces the carbon footprint through the use of renewable materials.

[0072] In one embodiment of the present invention, the method for preparing the surface carboxylated graphene nanosheets comprises:

[0073] The specific surface area ≥800m 2 / g of graphene nanosheets were dispersed in a mixture of concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1);

[0074] Ultrasonic treatment at 60-70°C for 2-3 hours;

[0075] The mixture was filtered, washed with water until neutral, and vacuum dried at 60-80° C. for 12 hours to obtain surface carboxylated graphene nanosheets.

[0076] In one embodiment of the present invention, the method for preparing the surface carboxylated carbon nanotubes comprises:

[0077] The specific surface area ≥ 600m 2 / g of carbon nanotubes were dispersed in a mixture of concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1);

[0078] Ultrasonic treatment at 70-80°C for 3-4 hours;

[0079] The surface carboxylated carbon nanotubes were obtained by suction filtration, water washing to neutral, and vacuum drying at 80-100℃ for 12 hours.

[0080] In an embodiment of the present application, the method for preparing the bio-based polyurethane having NCO and OH functional groups comprises:

[0081] Castor oil and polyethylene glycol were used as raw materials and mixed in a molar ratio of 1:1;

[0082] Diisocyanate was added and stirred at 60-70℃ for 2-3 hours;

[0083] Cooling to room temperature, the bio-based polyurethane having NCO and OH functional groups was obtained.

[0084] In an embodiment of the present application, the particle size of the aluminum polyphosphate corrosion inhibitor is 0.5-1μm.

[0085] In an embodiment of the present application, the molecular weight of the polyethylene glycol lubricant is 2000-4000.

[0086] In an embodiment of the present application, the method for preparing the composite proppant comprises:

[0087] The components were mixed in proportion, and anhydrous ethanol with a volume fraction of 30-40% was added;

[0088] Mixed uniformly in a high-speed mixer at a speed of 800-1000rpm for 15-20 minutes;

[0089] Dried at 80-100℃ for 4-6 hours to obtain the composite proppant.

[0090] For a clearer understanding, the following examples are described in detail below.

[0091] Example 1:

[0092] Formulation composition (by weight fraction):

[0093] Surface silane-modified fly ash: 57 parts

[0094] Surface-activated quartz sand: 28 parts

[0095] Surface-modified basalt fiber: 4 parts

[0096] Surface carboxylated graphene nanosheet: 2 parts

[0097] Surface carboxylated carbon nanotubes: 1.5 parts

[0098] Bio-based polyurethane having NCO and OH functional groups: 1.5 parts

[0099] Aluminum polyphosphate corrosion inhibitor: 0.8 parts

[0100] Polyethylene glycol lubricant: 0.8 parts

[0101] Preparation steps:

[0102] Fly ash treatment: the particle size is 20μm and the specific surface area is 350m 2 / g of fly ash is vacuum dried at 80°C for 4 hours; the dried fly ash is dispersed in anhydrous ethanol, 3wt% of KH550 silane coupling agent is added, and the mixture is stirred and reacted at 60°C for 2 hours; after filtration and washing, the mixture is dried at 60°C for 8 hours to obtain surface silanized fly ash.

[0103] Quartz sand treatment: Quartz sand with a particle size of 45 μm and a purity of 99.5% was ultrasonically cleaned with deionized water and anhydrous ethanol in sequence; immersed in a 10 wt % NaOH solution and treated at 90° C. for 1 hour; neutralized with dilute HCl to neutrality, washed with water, and dried to obtain surface-activated quartz sand.

[0104] Basalt fiber treatment: Basalt fiber with an aspect ratio of 100 was vacuum dried at 120°C for 2 hours; immersed in a 3wt% KH560 silane coupling agent solution and ultrasonically treated at room temperature for 30 minutes; filtered, washed, and dried at 80°C for 4 hours to obtain surface-modified basalt fiber.

[0105] Graphene nanosheet processing: Surface area of ​​800m 2 / g of graphene nanosheets were dispersed in concentrated sulfuric acid and concentrated nitric acid (volume ratio of 3:1), and ultrasonically treated at 60°C for 2 hours; filtered, washed with water until neutral, and vacuum dried at 60°C for 12 hours to obtain surface carboxylated graphene nanosheets.

[0106] Carbon nanotube processing: the specific surface area is 600m 2 / g of carbon nanotubes were dispersed in concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1), and ultrasonically treated at 70°C for 3 hours; filtered, washed with water until neutral, and vacuum dried at 80°C for 12 hours to obtain surface carboxyl carbon nanotubes.

[0107] Preparation of bio-based polyurethane: Castor oil and polyethylene glycol were mixed in a molar ratio of 1:1, diisocyanate was added, and the mixture was stirred at 60°C for 2 hours; then cooled to room temperature to obtain a bio-based polyurethane with NCO and OH functional groups.

[0108] Preparation of composite proppant: Mix the components according to the above weight ratio, add 30% anhydrous ethanol; stir at 800 rpm in a high-speed blender for 15 minutes to mix evenly; dry at 80°C for 4 hours to obtain a high-strength environmentally friendly ceramsite fracture proppant.

[0109] Example 2:

[0110] Formula composition (by weight):

[0111] Surface silanized fly ash: 60 parts

[0112] Surface activated quartz sand: 30 parts

[0113] Surface modified basalt fiber: 5 parts

[0114] Surface carboxylated graphene nanosheets: 3 parts

[0115] Surface carboxylated carbon nanotubes: 2 parts

[0116] Bio-based polyurethane with NCO and OH functional groups: 2 parts

[0117] Aluminum polyphosphate anti-corrosion agent: 1 part

[0118] Polyethylene glycol lubricant: 1 part

[0119] Preparation steps:

[0120] Fly ash treatment: the particle size is 30μm and the specific surface area is 400m 2 / g of fly ash was vacuum dried at 90°C for 5 hours; the dried fly ash was dispersed in anhydrous ethanol, 4wt% of KH550 silane coupling agent was added, and the mixture was stirred and reacted at 65°C for 2.5 hours; after filtration and washing, the mixture was dried at 70°C for 10 hours to obtain surface silanized fly ash.

[0121] Quartz sand treatment: Quartz sand with a particle size of 60 μm and a purity of 99.5% was ultrasonically cleaned with deionized water and anhydrous ethanol in sequence; immersed in a 12.5 wt % NaOH solution at 92.5° C. for 1.5 hours; neutralized to neutrality with dilute HCl, washed with water, and dried to obtain surface-activated quartz sand.

[0122] Basalt fiber treatment: Basalt fiber with an aspect ratio of 125 was vacuum dried at 135°C for 2.5 hours; immersed in a 4wt% KH560 silane coupling agent solution and ultrasonically treated at room temperature for 45 minutes; filtered, washed, and dried at 90°C for 5 hours to obtain surface-modified basalt fiber.

[0123] Graphene nanosheet processing: the specific surface area is 900m 2 / g of graphene nanosheets were dispersed in concentrated sulfuric acid and concentrated nitric acid (volume ratio of 3:1), ultrasonically treated at 65°C for 2.5 hours; filtered, washed with water until neutral, and vacuum dried at 70°C for 12 hours to obtain surface carboxylated graphene nanosheets.

[0124] Carbon nanotube treatment: carbon nanotubes with specific surface area 700 m 2 / g were dispersed in concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1) and ultrasonically treated at 75℃ for 3.5 hours; suction filtered, washed with water to neutral, and vacuum dried at 90℃ for 12 hours to obtain surface carboxylated carbon nanotubes.

[0125] Bio-based polyurethane preparation: castor oil and polyethylene glycol were mixed at a molar ratio of 1:1, diisocyanate was added, and stirred at 65℃ for 2.5 hours; cooled to room temperature to obtain bio-based polyurethane with NCO and OH functional groups.

[0126] Composite proppant preparation: the components were mixed in the above weight ratio, 35% anhydrous ethanol was added; stirred in a high-speed blender at 900 rpm for 17 minutes, uniformly mixed; dried at 90℃ for 5 hours to obtain high-strength environmentally friendly ceramsite fracture proppant.

[0127] Example 3:

[0128] Formulation composition (by weight fraction):

[0129] Surface silane-modified fly ash: 63 parts

[0130] Surface-activated quartz sand: 32 parts

[0131] Surface-modified basalt fiber: 6 parts

[0132] Surface carboxylated graphene nanosheet: 4 parts

[0133] Surface carboxylated carbon nanotubes: 2.5 parts

[0134] Bio-based polyurethane with NCO and OH functional groups: 2.5 parts

[0135] Polyaluminum phosphate corrosion inhibitor: 1.2 parts

[0136] Polyethylene glycol lubricant: 1.2 parts

[0137] Preparation steps:

[0138] Fly ash treatment: fly ash with particle size 45 μm and specific surface area 450 m 2 / g was vacuum dried at 100℃ for 6 hours; the dried fly ash was dispersed in anhydrous ethanol, 5wt% KH550 silane coupling agent was added, and stirred at 70℃ for 3 hours; suction filtered, washed, and dried at 80℃ for 12 hours to obtain surface silane-modified fly ash.

[0139] Quartz sand treatment: Quartz sand with particle size of 75 μm and purity of 99.5% was sequentially cleaned with deionized water and anhydrous ethanol by ultrasonic washing; soaked in 15 wt% NaOH solution, treated at 95℃ for 2 hours; neutralized to neutral with dilute HCl, washed with water and dried to obtain surface-activated quartz sand.

[0140] Basalt fiber treatment: Basalt fiber with aspect ratio of 150 was vacuum dried at 150℃ for 3 hours; soaked in 5 wt% KH560 silane coupling agent solution, ultrasonically treated at room temperature for 60 minutes; filtered, washed and dried at 100℃ for 6 hours to obtain surface-modified basalt fiber.

[0141] Graphene nanoplatelet treatment: Graphene nanoplatelets with specific surface area of 1000 m 2 / g were dispersed in concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1) and ultrasonically treated at 70℃ for 3 hours; suction filtered, washed with water to neutral and vacuum dried at 80℃ for 12 hours to obtain surface-carboxylated graphene nanoplatelets.

[0142] Carbon nanotube treatment: Carbon nanotubes with specific surface area of 800 m 2 / g were dispersed in concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1) and ultrasonically treated at 80℃ for 4 hours; suction filtered, washed with water to neutral and vacuum dried at 100℃ for 12 hours to obtain surface-carboxylated carbon nanotubes.

[0143] Bio-based polyurethane preparation: Castor oil and polyethylene glycol were mixed in a molar ratio of 1:1, diisocyanate was added, and the mixture was stirred at 70℃ for 3 hours; cooled to room temperature to obtain bio-based polyurethane with NCO and OH functional groups.

[0144] Composite proppant preparation: The components were mixed in the above weight ratio, 40% anhydrous ethanol was added; stirred in a high-speed blender at 1000 rpm for 20 minutes to mix uniformly; dried at 100℃ for 6 hours to obtain high-strength environmentally friendly ceramsite fracture proppant.

[0145] Test Example 1

[0146] Objective: To evaluate the physical stability of high-strength environmentally friendly ceramsite fracture proppant in higher temperature and high-pressure reservoir environments, and to ensure its reliability and effectiveness in various practical applications.

[0147] Methods: High-temperature and high-pressure reaction kettles were used for high-temperature and high-pressure soaking tests in different reservoir environments.

[0148] Steps:

[0149] Sample preparation:

[0150] The high-strength environmentally friendly ceramsite fracture proppant (Example 2) and traditional silica sand were sieved according to the standard particle size range (20-40 mesh).

[0151] Prepare a certain number of particle samples (e.g., 100 particles).

[0152] Equipment calibration:

[0153] Calibrate high-temperature and high-pressure reactors to ensure accurate temperature and pressure control.

[0154] Testing process:

[0155] The proppant particles are placed in a reactor and a fracturing fluid (such as an aqueous solution containing an appropriate amount of salt and a pH regulator) is added.

[0156] Set up multiple test conditions:

[0157] Test group 1: 200°C, 1000ps i, 72 hours

[0158] Test Group 2: 250°C, 1500ps i, 72 hours

[0159] Test Group 3: 300°C, 2000ps i, 72 hours

[0160] Test each group of conditions separately.

[0161] After the test, the particles were taken out, cleaned and dried, and the morphological changes and mass loss of the particles were recorded.

[0162] Data Analysis:

[0163] The mass loss percentage (MLP) and particle breakage rate were calculated to evaluate its stability under different high temperature and high pressure environments.

[0164] Experimental data:

[0165]

[0166]

[0167]

[0168] Result analysis:

[0169] Composite proppant:

[0170] 200℃ / 1000psi: The average mass loss rate is 0.2%, and the particle breakage rate is 1.5%, showing extremely high stability.

[0171] 250℃ / 1500psi: The mass loss rate is 0.8% on average, and the particle breakage rate is 1.85%, which increases slightly but still maintains good stability.

[0172] 300℃ / 2000psi: The average mass loss rate is 1.8%, and the particle breakage rate is 2.75%. It still has strong stability under high temperature and high pressure conditions.

[0173] Traditional silica sand:

[0174] Under all test conditions, the mass loss rate and particle breakage rate were significantly higher than those of the composite proppant, especially at 300°C / 2000 psi, where the breakage rate reached 28%.

[0175] in conclusion:

[0176] By increasing the test temperature to 200°C, 250°C, and 300°C, the experimental results further verified the excellent performance of the high-strength, environmentally friendly ceramsite fracture proppant of the present invention under higher temperature and high pressure environments:

[0177] High temperature and high pressure stability: The composite proppant can still maintain low mass loss rate and particle breakage rate under conditions as high as 300℃ and 2000psi, which is significantly better than traditional silica sand.

[0178] Strong adaptability: Composite proppants are suitable for a wider range of reservoir environments, especially high-temperature and high-pressure oil wells, ensuring their reliability and effectiveness under various extreme conditions.

[0179] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to fall within the scope of protection claimed in the present invention.

Claims

1. A high-strength environmentally friendly ceramsite fracture proppant, characterized in that: The following components are included in parts by weight: Surface silanized fly ash: 60 parts; Surface activated quartz sand: 30 parts; Surface modified basalt fiber: 5 parts; Surface carboxylated graphene nanosheets: 3 parts; Surface carboxylated carbon nanotubes: 2 parts; Bio-based polyurethane with NCO and OH functional groups: 2 parts; Aluminum polyphosphate anti-corrosion agent: 1 part; Polyethylene glycol lubricant: 1 part; The preparation method of the surface silanized fly ash comprises: Dry fly ash with a particle size of 20-45 μm and a specific surface area of ​​350-450 m² / g in vacuum at 80-100°C for 4-6 hours; Disperse the dried fly ash in anhydrous ethanol, add 3-5wt% of silane coupling agent KH550, and stir the mixture at 60-70°C for 2-3 hours; Filtering, washing, and drying at 60-80° C. for 8-12 hours to obtain fly ash with surface silanization modification; The preparation method of the surface-activated quartz sand comprises: Quartz sand with a particle size of 45-75 μm and a purity of ≥99.5% was ultrasonically cleaned with deionized water and anhydrous ethanol in sequence; Soak the cleaned quartz sand in 10-15wt% NaOH solution at 90-95℃ for 1-2 hours; Neutralize with dilute HCl to neutrality, wash with water, and dry to obtain surface-activated quartz sand; The preparation method of the surface-modified basalt fiber comprises: Basalt fiber with an aspect ratio of 100-150 is vacuum dried at 120-150°C for 2-3 hours; The dried fiber was immersed in a 3-5wt% silane coupling agent KH560 solution and ultrasonically treated at room temperature for 30-60 minutes; Filtering, washing, and drying at 80-100° C. for 4-6 hours to obtain surface-modified basalt fibers; The preparation method of the proppant comprises: Mix the components in proportion and add 30-40% anhydrous ethanol by volume; Mix well in a high-speed blender at a speed of 800-1000 rpm for 15-20 minutes; The proppant is obtained by drying at 80-100° C. for 4-6 hours.

2. The high-strength, environmentally friendly ceramsite fracture proppant according to claim 1, characterized in that: The preparation method of the surface carboxylated graphene nanosheets comprises: Graphene nanosheets with a specific surface area of ​​≥800 m² / g are dispersed in a mixture of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1; Ultrasonic treatment at 60-70°C for 2-3 hours; The mixture was filtered, washed with water until neutral, and vacuum dried at 60-80° C. for 12 hours to obtain surface carboxylated graphene nanosheets.

3. The high-strength environmentally friendly ceramsite fracture proppant according to claim 1, characterized in that: The preparation method of the surface carboxylated carbon nanotubes comprises: Dispersing carbon nanotubes with a specific surface area of ​​600 m² / g or more in a mixture of concentrated sulfuric acid and concentrated nitric acid at a volume ratio of 3:1; Ultrasonic treatment at 70-80°C for 3-4 hours; The mixture was filtered, washed with water until neutral, and dried in vacuum at 80-100° C. for 12 hours to obtain surface carboxyl-grouped carbon nanotubes.

4. The high-strength, environmentally friendly ceramsite fracture proppant according to claim 1, characterized in that: The preparation method of the bio-based polyurethane having NCO and OH functional groups comprises: Castor oil and polyethylene glycol are used as raw materials and mixed in a molar ratio of 1:1; Add diisocyanate and stir the reaction at 60-70°C for 2-3 hours; After cooling to room temperature, bio-based polyurethane with NCO and OH functional groups was obtained.

5. The high-strength, environmentally friendly ceramsite fracture proppant according to claim 1, characterized in that: The particle size of the polyaluminum phosphate anti-corrosion agent is 0.5-1 μm.

6. The high-strength, environmentally friendly ceramsite fracture proppant according to claim 1, characterized in that: The molecular weight of the polyethylene glycol lubricant is 2000-4000.

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