Fracturing propping agent with quantum dot tracing function and preparation method and application thereof

Abstract

The invention provides a fracturing propping agent with a quantum dot tracing function for oil and gas exploitation as well as application and a preparation method of the fracturing propping agent. The fracturing propping agent sequentially comprises a matrix layer, a fluorescent layer and a microgel layer from inside to outside, wherein the matrix layer is coated with the fluorescent layer, and the fluorescent layer is coated with the microgel layer; the fluorescent layer comprises a light-cured resin composition and a quantum dot tracing composition; the quantum dot tracing composition comprises modified fluorescent quantum dots, the modified fluorescent quantum dots are obtained by grafting a silane coupling agent on the surfaces of the fluorescent quantum dots, and the silane coupling agent is gamma-methacryloxypropyltrimethoxysilane; the microgel layer comprises a pH / mineralization degree dual-response hydrogel system. The modified quantum dots and the light-cured resin composition are covalently cross-linked, a three-layer composite structure is adopted, the functions of supporting, quantum dot tracing and pH / mineralization degree response are provided, the method is suitable for low-temperature reservoirs, the energy consumption is low, the stability is high, the coding tracing capacity is high, and accurate monitoring and flow guide dynamic regulation and control of multi-section fracturing productivity are achieved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, specifically relating to a fracturing proppant with quantum dot tracer function, its preparation method, and its application. Background Technology

[0002] In the modern oil and gas industry, horizontal well multi-stage fracturing technology is a key core technology in the development of unconventional oil and gas resources. To accurately analyze the production capacity of each subsurface segment after hydraulic fracturing operations, as well as the location and geometry of the resulting hydraulic fractures, tracers are typically mixed with fracturing proppant. The relative content of the tracer in the proppant of each segment is detected to determine the oil and gas characteristics in the analyzed oilfield well network, such as downhole fracture morphology, the proportion of oil production contribution along the fracturing line, and inter-well interference. Traditional tracers have limitations. Chemical tracers are easily affected by complex subsurface fluids (such as high-salinity brine and sulfur-containing fluids), resulting in large monitoring deviations, poor sensitivity, and decomposition of compounds at excessively high downhole temperatures. Furthermore, the limited variety of compounds makes them unsuitable for multi-stage monitoring. Isotope tracers pose radiation safety risks, have high costs for storage, transportation, and construction management, present safety and compliance risks, and cause significant environmental pollution. Micro-tracers (such as nanoparticle tracers) are expensive, prone to aggregation, complex to use, and costly to detect, posing risks of aggregation and blockage, and cannot achieve long-term continuous monitoring.

[0003] In summary, although tracer-type fracturing proppants have great application potential in horizontal well development, many problems still exist regarding tracer coating processing methods and tracer performance. The core issues of existing quantum dot tracer proppants are: In recent years, publicly disclosed quantum dot proppant technologies have all adopted thermosetting or solvent evaporation methods for preparation. These methods have several significant drawbacks: low process efficiency and high energy consumption. Thermosetting requires a high-temperature environment of 120-150℃, with a reaction cycle of 4-8 hours and a unit energy consumption of 1.2 kWh / kg. Furthermore, high temperatures can easily lead to fluorescence quenching of quantum dots (fluorescence intensity loss of over 15%). Solvent evaporation requires large amounts of organic solvents (such as toluene and ethyl acetate), causing environmental pollution after volatilization, and residual solvents can reduce the mechanical properties of the proppant. Quantum dots have poor stability; the bond between quantum dots and the proppant matrix is ​​mostly physical, without chemical bonds. Under long-term immersion in formation fluids, the shedding rate reaches 3%-5%, and the monitoring cycle is only 2-4 years, which cannot meet the "long-cycle development" requirements of unconventional oil and gas reservoirs. Environmental adaptability is also limited: thermosetting processes do not cure completely in low-temperature reservoirs ≤80℃ (such as the Linfen tight gas reservoir and shallow shale gas reservoirs in the Sichuan Basin), causing a sharp drop in proppant compressive strength of over 40%, easily leading to breakage and crack blockage, thus affecting development results. Furthermore, existing quantum dot proppants mostly employ physical mixing methods, leading to easy detachment of quantum dots and short monitoring cycles. Therefore, developing a quantum dot fracturing proppant that can stably bind to proppant, is suitable for cryogenic environments, and supports multi-segment coded tracing is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and provide a fracturing proppant with quantum dot tracer function for oil and gas development, which can realize accurate monitoring and dynamic control of multi-stage fracturing capacity and is suitable for unconventional oil and gas resource development.

[0005] This invention is achieved through the following technical solution: A fracturing proppant with quantum dot tracer function used in oil and gas development comprises, from the inside out, a matrix layer, a fluorescent layer coated on the matrix layer, and a microgel layer coated on the fluorescent layer; the fluorescent layer comprises a photocurable resin composition and a quantum dot tracer composition; the quantum dot tracer composition comprises modified fluorescent quantum dots, wherein the modified fluorescent quantum dots are obtained by grafting a silane coupling agent onto the surface of the fluorescent quantum dots, and the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane; the microgel layer comprises a pH / mineralization dual-responsive hydrogel system.

[0006] This invention provides a fracturing proppant with quantum dot tracer function for oil and gas development. It employs a three-layer composite structure, sequentially comprising a matrix layer, a fluorescent layer coating the matrix layer, and a microgel layer coating the fluorescent layer. The matrix layer provides support, the fluorescent layer contains the quantum dot tracer and a photocurable resin, and the microgel layer exhibits pH / mineralization response. The fluorescent quantum dots are surface-modified with γ-methacryloyloxypropyltrimethoxysilane to introduce acryloyl groups, facilitating covalent cross-linking with the photocurable resin composition. This ensures a tight bond between the quantum dot tracer composition and the photocurable resin composition, reducing the shedding rate of the quantum dot tracer composition. Furthermore, the fluorescent layer can be formed at room temperature using a photocuring process, making it suitable for low-temperature reservoirs. The resulting fracturing proppant exhibits low energy consumption, high stability, and strong coding tracer capability with quantum dot tracer function. The fracturing proppant provided by this invention enables precise monitoring and dynamic control of multi-stage fracturing capacity, making it suitable for unconventional oil and gas resource development.

[0007] Furthermore, the mass ratio of silane coupling agent to fluorescent quantum dots is 1:1 to 2:1. The ratio of silane coupling agent to fluorescent quantum dots is controlled to graft a sufficient amount of polymerizable acryloyl groups onto the fluorescent quantum dots.

[0008] Furthermore, the fluorescent quantum dots include at least one of CdSe / ZnS core-shell quantum dots, carbon quantum dots, graphene quantum dots, perovskite quantum dots, and CdTe / CdS quantum dots, with a particle size of 2-10 nm.

[0009] Furthermore, the photocurable resin composition includes a photocurable resin, a photoinitiator, and a reactive diluent; the photocurable resin includes a thermosensitive polymer formed by the polymerization of thermosensitive monomers, wherein the thermosensitive monomers include at least one selected from N-isopropylacrylamide and poly(D,L-lactide-co-ε-caprolactone) acrylate. The photocurable resin, comprising a thermosensitive polymer formed by the polymerization of thermosensitive monomers, enables the fluorescent layer to possess thermally induced shape memory function after photocuring, allowing it to undergo volume expansion or structural recovery under formation temperature to repair microcracks.

[0010] Furthermore, in the photocurable resin composition, the photocurable resin is 50-70 parts by weight, the photoinitiator is 2-5 parts by weight, and the diluent is 10-20 parts by weight.

[0011] Furthermore, the pH / mineralization dual-responsive hydrogel system comprises an acrylic acid-N-isopropylacrylamide-dimethylaminoethyl methacrylate terpolymer microgel.

[0012] Furthermore, the matrix layer accounts for 70-90% of the total weight of the fracturing proppant; the fluorescent layer accounts for 5-25% of the total weight of the fracturing proppant; and the microgel layer accounts for 1-5% of the total weight of the fracturing proppant.

[0013] Furthermore, the thickness of the fluorescent layer is 1-100 μm; the thickness of the microgel layer is 100-500 nm.

[0014] This invention also provides the application of the fracturing proppant with quantum dot tracer function used in the above-mentioned oil and gas development in the multi-stage fracturing production monitoring of horizontal wells. Different coded fracturing proppants are injected into different fracturing sections, and by exciting the fluorescence of the fluorescent layer and detecting the returned drainage spectrum, the segmented production capacity of different fracturing sections can be identified.

[0015] This invention also provides a method for preparing quantum dot tracers for oil and gas development, comprising the following steps: dispersing quantum dots in a solvent, adding a silane coupling agent, stirring and reacting, centrifuging, and drying, wherein the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane, to obtain quantum dot tracer composition particles; mixing a photocurable resin, a photoinitiator, and a diluent to obtain a photocurable slurry; adding the quantum dot tracer composition particles to the photocurable slurry, adding an antioxidant and a hydrophobic modifier to uniformly disperse the quantum dot tracer composition particles, to obtain a fluorescent layer slurry; spraying the fluorescent layer slurry onto the surface of the matrix particles, irradiating the fluorescent layer slurry with a photocurable light source to photocur and coat the surface of the matrix particles, to obtain matrix particles coated with a fluorescent layer; immersing the matrix particles coated with the fluorescent layer in a microgel solution, depositing a microgel outer layer on the surface of the matrix particles coated with the fluorescent layer, to obtain composite particles; drying, dispersing, cooling, and sieving the composite particles to obtain a fracturing proppant.

[0016] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the fracturing proppant with quantum dot tracer function used in the oil and gas development of Example 1.

[0018] Figure 2 This is a flowchart of the preparation of fracturing proppant in Example 4. Detailed Implementation

[0019] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the embodiments of the present invention, and not all structures.

[0020] Example 1 This embodiment provides a fracturing proppant with quantum dot tracer function for use in oil and gas development. Figure 1This is a structural diagram of fracturing proppant. Please refer to [link / reference]. Figure 1 The fracturing proppant comprises, from the inside out, a matrix layer 1, a fluorescent layer 2 coated on the matrix layer 1, and a microgel layer 3 coated on the fluorescent layer 2. The fluorescent layer 2 comprises a photocurable resin composition and a quantum dot tracer composition. The quantum dot tracer composition comprises modified fluorescent quantum dots, which are obtained by grafting a silane coupling agent onto the surface of the fluorescent quantum dots. The silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane. The microgel layer 3 comprises a pH / mineralization dual-responsive hydrogel system.

[0021] This embodiment provides a fracturing proppant with quantum dot tracer function for oil and gas development. It employs a three-layer composite structure, sequentially comprising a matrix layer 1, a fluorescent layer 2 coating the matrix layer 1, and a microgel layer 3 coating the fluorescent layer 2 from the inside out. The matrix layer 1 provides support, the fluorescent layer 2 contains the quantum dot tracer and a photocurable resin, and the microgel layer 3 has dual pH / mineralization response. The fluorescent quantum dots are surface-modified with γ-methacryloyloxypropyltrimethoxysilane to introduce acryloyl groups, facilitating covalent cross-linking with the photocurable resin composition. This ensures a tight bond between the quantum dot tracer composition and the photocurable resin composition, reducing the shedding rate of the quantum dot tracer composition. Furthermore, the fluorescent layer 2 can be formed at room temperature using a photocuring process, making it suitable for low-temperature reservoirs. The resulting fracturing proppant exhibits low energy consumption, high stability, and strong coding tracer capability with quantum dot tracer function. The fracturing proppant provided in this embodiment enables precise monitoring and dynamic control of multi-stage fracturing capacity, making it suitable for unconventional oil and gas resource development.

[0022] In this embodiment, the matrix layer 1, as a low-density, high-strength skeleton particle, accounts for 70-90% of the total weight of the fracturing proppant. The matrix layer 1 is selected from one or more of quartz sand, ceramsite, silicone resin microspheres or polymethyl methacrylate particles, with a particle size range of 50-200 mesh, a bulk density of 0.9-2 g / cm³, and a breakage rate of less than 10% in the 60MPa fracture resistance test.

[0023] In this embodiment, the mass ratio of silane coupling agent to fluorescent quantum dots is 1:1-2:1. The ratio of silane coupling agent to fluorescent quantum dots is controlled to introduce a sufficient amount of polymerizable acryloyl groups onto the fluorescent quantum dots. In fluorescent layer 2, silane is grafted onto the surface of the quantum dots using a silane coupling agent γ-methacryloyloxypropyltrimethoxysilane (such as KH-570), introducing polymerizable acryloyl groups to obtain modified fluorescent quantum dots. The acryloyl groups on the surface of the modified fluorescent quantum dots can undergo a crosslinking reaction with the photocurable resin in the photocurable resin composition under the action of an initiator, and copolymerize via free radical polymerization (such as AIBN initiation).

[0024] In one embodiment, the mass ratio of silane coupling agent to fluorescent quantum dots is 1:1. In another embodiment, the mass ratio of silane coupling agent to fluorescent quantum dots is 2:1.

[0025] In this embodiment, the fluorescent quantum dots include at least one of CdSe / ZnS core-shell quantum dots, carbon quantum dots, graphene quantum dots, and perovskite quantum dots, with a particle size of 2-10 nm and an emission wavelength that is tunable in the range of 450-680 nm.

[0026] In one embodiment, the fluorescent quantum dots are CdSe / ZnS core-shell structures, covalently connected to a temperature-sensitive shape memory polymer network to achieve dual-wavelength emission (450-680nm), and different particle size combinations can form ≥1000 tracer codes.

[0027] In this embodiment, the photocurable resin composition includes a photocurable resin, a photoinitiator, and a reactive diluent. The photocurable resin comprises a thermosensitive polymer formed by the polymerization of thermosensitive monomers, wherein the thermosensitive monomers include at least one of N-isopropylacrylamide and poly(D,L-lactide-co-ε-caprolactone) acrylate. In the fluorescent layer 2, quantum dots form a cross-linked thermosensitive polymer network with the photocurable resin. The quantum dots are covalently bonded therein as cross-linking points, exhibiting excellent mechanical properties. The quantum dots are uniformly distributed in the polymer, enabling the linkage between thermosensitive response (such as swelling / shrinkage) and fluorescence performance in a bottom-hole environment.

[0028] In this embodiment, the photocurable resin composition comprises 50-70 parts by weight of photocurable resin, 2-5 parts by weight of photoinitiator, and 10-20 parts by weight of diluent.

[0029] In this embodiment, the pH / mineralization dual-responsive hydrogel system comprises an acrylic acid (AA)-N-isopropylacrylamide (NIPAM)-dimethylaminoethyl methacrylate (DMAEMA) ternary copolymer microgel. The microgel layer 3 exhibits both pH and mineralization responses, with a volume change rate ≥100% in acid, alkali, and salt solutions, enabling dynamic control of the flow channels.

[0030] In this embodiment, the thickness of the fluorescent layer 2 is 1-100 μm; the thickness of the microgel layer 3 is 100-500 nm.

[0031] In this embodiment, the matrix layer 1 accounts for 70-90% of the total weight of the fracturing proppant; the fluorescent layer 2 accounts for 5-25% of the total weight of the fracturing proppant; and the microgel layer 3 accounts for 1-5% of the total weight of the fracturing proppant.

[0032] The fracturing proppant provided in this embodiment utilizes the nano-size effect of fluorescent quantum dots and their stability advantages as inorganic materials. After modification with a coupling agent, the fluorescent quantum dots are cross-linked with a photocurable resin, allowing the modified fluorescent quantum dots to be incorporated into the photocurable resin network. This enables its application as a fracturing proppant and in horizontal well staged production monitoring. The strong covalent bond between the fluorescent quantum dots and the photocurable resin endows the fracturing proppant with excellent stability. Its structure is difficult to disrupt even in underground environments with high temperature, high humidity, high pressure, and unknown acidity / alkalinity. The emission wavelength and full width at half maximum (FWHM) of the fluorescent quantum dots are difficult to alter, demonstrating excellent stability. Therefore, quantitative monitoring can be achieved in complex well site environments. As a highly efficient stimulated photoluminescence material, fluorescent quantum dots exhibit extremely high detection sensitivity. Only a small amount of ultraviolet light is needed to excite them, causing them to emit strong fluorescence. At this point, a simple handheld spectrometer can be used to analyze the wavelength and FWHM characteristics of the fluorescent quantum dots, enabling real-time online detection. The fracturing proppant provided in this embodiment features a novel polymer network multilayer cross-linking process, which is faster and simpler to operate than thermosetting, and has broad application prospects. This invention overcomes the shortcomings of existing technologies where the physical bond between photocured quantum dots and the proppant matrix is ​​prone to detachment. A stable structure is formed through robust covalent bonding, extending the monitoring period to over 5 years. It is suitable for the ultra-high pressure, high temperature, and high salinity conditions of downhole oil and gas wells, ensuring integrity and tracer stability. Furthermore, the fracturing proppant provided in this embodiment can achieve coded monitoring of multi-stage fracturing in horizontal wells by adjusting the proportion of different quantum dots, with a production contribution identification error ≤1.5%. Compared to existing technologies, the fracturing proppant provided in this embodiment does not require well shut-in monitoring. The emission wavelength and full width at half maximum (FWHM), two quantitative characteristics of quantum dots, provide more accurate and sensitive detection than the single element or functional group characteristics of other types of tracers. Moreover, the emission wavelength and FWHM can be varied within a wide range, allowing for the creation of various quantum dot tracers suitable for different coded monitoring needs.

[0033] Example 2 This embodiment provides a method for preparing the fracturing proppant with quantum dot tracer function used in oil and gas development as described in Example 1. Figure 2 This is a flowchart of the preparation of the fracturing proppant in Example 1. Please refer to [link / reference]. Figure 2 This includes the following steps: Step S1: Disperse quantum dots in a solvent, add a silane coupling agent, stir to react, centrifuge, and dry. The silane coupling agent is γ-methacryloxypropyltrimethoxysilane. Quantum dot tracer composition particles are obtained. Step S2: Mix the photocurable resin, photoinitiator, and diluent to obtain the photocurable slurry; Step S3: Add the quantum dot tracer composition particles to the photocurable slurry, add antioxidants and hydrophobic modifiers to make the quantum dot tracer composition particles uniformly dispersed, and obtain the fluorescent layer 2 slurry; Step S4: Spray fluorescent layer 2 slurry onto the surface of the matrix layer 1 particles, and use a light curing light source to irradiate the fluorescent layer 2 slurry to light-cur and coat the surface of the matrix layer 1 particles, thus obtaining matrix layer 1 particles coated with fluorescent layer 2. Step S5: Immerse the matrix layer 1 particles coated with fluorescent layer 2 into the microgel solution, and deposit the microgel outer layer on the surface of the matrix layer 1 particles coated with fluorescent layer 2 to obtain composite particles. Step S6: Dry, disperse, cool and sieve the composite particles to obtain fracturing proppant.

[0034] In one embodiment, in step S1, fluorescent quantum dots are dispersed in a solvent, a silane coupling agent is added, the mixture is stirred, centrifuged, and dried to obtain quantum dot tracer composition particles. The silane coupling agent is γ-methacryloxypropyltrimethoxysilane. Specifically, CdSe / ZnS fluorescent quantum dots are dispersed in anhydrous ethanol to form a 0.5%-1% quantum dot ethanol solution. The silane coupling agent γ-methacryloxypropyltrimethoxysilane (KH-570) is added, with a mass ratio of silane coupling agent to fluorescent quantum dots of 1:1-2:1. The mixture is stirred in a constant temperature water bath at 50-60℃ for 1-2 hours to graft double bonds onto the surface of the fluorescent quantum dots, thus modifying them. After the reaction, the modified fluorescent quantum dots are separated by high-speed centrifugation (8000 r / min, 10 minutes) and dried in a vacuum drying oven at 60℃ for 2 hours to obtain quantum dot tracer composition particles. The modified fluorescent quantum dots have acryloyl groups grafted onto their surface, which facilitates cross-linking with photocurable resins, reduces the shedding rate of fluorescent quantum dots in fracturing proppant, and avoids the problem of easy shedding due to physical mixing.

[0035] In one embodiment, the mass-to-volume ratio of fluorescent quantum dots to anhydrous ethanol is 1:200-1:400 (g / mL).

[0036] In one embodiment, the fluorescent quantum dots include at least one of CdSe / ZnS quantum dots, carbon quantum dots, graphene quantum dots, or perovskite quantum dots, with a particle size of 2-10 nm, an emission wavelength of 450-680 nm, and a full width at half maximum (FWHM) of 15-30 nm.

[0037] In one embodiment, the fluorescent quantum dots include CdSe / ZnS red-green quantum dots with dual emission wavelengths of 530nm / 620nm.

[0038] In step S2, the photocurable resin, photoinitiator and reactive diluent are mixed to obtain a photocurable slurry, wherein the photocurable resin is 50-70 parts by weight, the photoinitiator is 2-5 parts by weight, and the reactive diluent is 10-20 parts by weight.

[0039] In one embodiment, the photocurable resin comprises a thermosensitive polymer formed by polymerizing a thermosensitive monomer, which includes at least one of N-isopropylacrylamide and poly(D,L-lactide-co-ε-caprolactone) acrylate. This enables the fluorescent layer 2 to possess thermally induced shape memory function after curing, allowing it to undergo volume expansion or structural recovery under formation temperature to repair microcracks. In the fluorescent layer 2, modified quantum dots form a cross-linked thermosensitive polymer network with the photocurable resin. The modified quantum dots are covalently bonded therein as cross-linking points, exhibiting excellent mechanical properties. The modified quantum dots are uniformly distributed in the photocurable resin, enabling the linkage between thermosensitive response (such as swelling / shrinkage) and fluorescence performance at the bottom of the well.

[0040] In one embodiment, the photoinitiator is selected from type 1173 photoinitiator or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and the reactive diluent is selected from trimethylolpropane triacrylate or isoborneol acrylate.

[0041] In one embodiment, the photocurable resin, photoinitiator, and diluent are mixed and stirred at a speed of 1500 r / min for 10 minutes.

[0042] In step S3, the quantum dot tracer composition particles prepared in step S1 are added to the photocurable slurry prepared in step S2, and antioxidants and hydrophobic modifiers are added to disperse the quantum dot tracer composition particles evenly, thereby obtaining fluorescent layer 2 slurry. In this slurry, the antioxidant is 0.5-1 parts by weight and the hydrophobic modifier is 3-5 parts by weight.

[0043] In one embodiment, the antioxidant is a type 1010 antioxidant, and the hydrophobic modifier is a fluorinated acrylate with a fluorine content of ≥15%.

[0044] In this embodiment, in step S3, the quantum dot tracer composition particles prepared in step S1 are added to the photocurable slurry prepared in step S2, and antioxidants and hydrophobic modifiers are added. The mixture is then dispersed at high speed at a rotation speed of 3000 r / min for 30 minutes to ensure that the quantum dot tracer composition particles are uniformly dispersed in the photocurable slurry.

[0045] In this embodiment, in step S4, a fluorescent layer 2 slurry is sprayed onto the surface of the matrix layer 1 particles. The fluorescent layer 2 slurry is then irradiated with a photocuring light source to photocur and coat the surface of the matrix layer 1 particles, resulting in matrix layer 1 particles coated with a fluorescent layer 2. Specifically, the proppant particles are preheated to 35-50°C, and the fluorescent layer 2 slurry is coated onto the surface of the matrix layer 1 particles using a fluidized bed spraying process. The particles are then irradiated with a photocuring light source at 35-60°C to achieve a crosslinking degree of ≥90% for the photocurable resin, thus achieving low-temperature curing. This process allows the fluorescent layer 2 slurry to photocur and coat the surface of the matrix layer 1, resulting in a matrix layer 1 coated with a fluorescent layer 2.

[0046] In one embodiment, a UV LED light source (365nm wavelength, power 400-500mW / cm²) is used to irradiate the resin at 35°C for 10-30 minutes, achieving a resin crosslinking degree ≥90% and realizing low-temperature complete curing. The coating thickness of the fluorescent layer 2 is controlled to ensure that the coating thickness of the fluorescent layer 2 is 1-100μm.

[0047] In one embodiment, the proppant particles are selected from 20-40 mesh quartz sand, ceramsite, or polymer particles.

[0048] In step S5, the substrate layer 1 particles coated with fluorescent layer 2 are immersed in a microgel solution, and a microgel outer layer is deposited on the surface of the substrate layer 1 particles coated with fluorescent layer 2 to obtain composite particles. Among them, acrylic acid (AA)-N-isopropylacrylamide (NIPAM)-dimethylaminoethyl methacrylate (DMAEMA) ternary copolymer microgel is used as a pH / mineralization dual-responsive hydrogel system to prepare a 5-20 w / w% pH / mineralization responsive microgel aqueous solution. Using layer-by-layer self-assembly technology, the substrate layer 1 particles coated with fluorescent layer 2 are immersed in the solution and deposited at 25-35℃ for 10-15 min, controlling the thickness of the microgel coating to be 100-500 nm.

[0049] Step S6: Dry, disperse, cool and sieve the composite particles to obtain fracturing proppant. The composite particles are placed in a 120℃ drying oven for evaporation for 2-3 hours, then immersed in 50ml of deionized water for ultrasonic dispersion for 30 minutes, cooled to room temperature and sieved using a 10-40 mesh standard sieve.

[0050] The fracturing proppant prepared in this embodiment can be mixed with fracturing fluid and injected into the formation as a single-wavelength quantum dot proppant (such as 520nm). It enters the target fracture segment with the fracturing fluid, and the fluorescence intensity is measured at the wellhead to invert the production.

[0051] In another embodiment, two to three different wavelength quantum dots are combined in a mass ratio (e.g., 470nm:530nm:620nm = 1:1:2) to prepare various modified quantum dots, forming pressure proppants with different codes, which are then mixed and injected into the system. Depending on the number of fracturing stages, a corresponding dual- or multi-wavelength coded pressure proppant is selected, with each stage matched with a unique tracer code combination. Using a downhole ultraviolet fiber optic system, the flowback fluid spectral signal is monitored in real time through controlled segmented irradiation from the ground, analyzing the production contribution of each fracturing stage. Under formation temperature, the thermosensitive polymer in the fluorescent layer 2 automatically recovers its three-dimensional structure, repairing micro-damage in the fractures. The outer microgel layer dynamically swells and contracts according to formation pH / mineralization, thereby regulating the cross-sectional area of ​​the flow channel.

[0052] The fracturing proppant in this embodiment adopts a three-layer composite structure of "matrix layer 1 - fluorescent layer 2 - microgel layer 3". The matrix layer 1 is a high-strength skeleton particle. The fluorescent layer 2 plays a photocuring tracer role. In the fluorescent layer 2, quantum dots are covalently embedded in the temperature-sensitive polymer network through a silane coupling agent, which solves the problems of easy detachment in traditional physical mixing and fluorescence quenching caused by thermal curing. The microgel layer 3 is a pH / mineralization responsive microgel system, which can dynamically adjust the conductivity according to the formation environment.

[0053] The fracturing proppant in this embodiment remains intact under simulated high-pressure closure pressure in oil and gas wells, with a fragmentation rate of ≤2%. After immersion in simulated 150°C, high-salinity formation water for 7 days, the fluorescence retention rate remains above 95%, and the temperature-sensitive shape memory polymer can automatically repair micro-damage in fractures. This durability index far exceeds the effects achievable by existing thermosetting technologies and ink technologies in the display field, demonstrating that the molecular-level covalent bond structure formed by the modified fluorescent quantum dots of the tracer and the photocurable resin network in the fluorescent layer 2 of the fracturing proppant enables long-term tracking in the downhole environment. Furthermore, the fluorescent quantum dots in this embodiment can also employ dual-wavelength quantum dot encoding technology, allowing for ≥1000 tracer combinations and resisting fluorescence interference from formation fluids.

[0054] Example 3 This embodiment provides a method for preparing fracturing proppant, including the following steps: Step S1: Disperse fluorescent quantum dots in a solvent, add a silane coupling agent, stir the reaction, centrifuge, and dry. The silane coupling agent is γ-methacryloxypropyltrimethoxysilane, to obtain a quantum dot tracer composition.

[0055] In this embodiment, the fluorescent quantum dots selected are CdSe / ZnS core-shell structured red and green quantum dots with dual emission wavelengths of 530nm / 620nm. The fluorescent quantum dots are dispersed in anhydrous butyl acetate (mass concentration 0.5%-1%), KH-570 is added (mass ratio of KH-570 to quantum dots 1:1-2:1), the mixture is stirred at 50-60℃ for 1-2 hours, centrifuged at 8000r / min for 10 minutes, and vacuum dried at 60℃ for 2 hours to obtain surface-modified quantum dots, thus obtaining the quantum dot tracer.

[0056] Step S2: Mix the photocurable resin, photoinitiator, and diluent to obtain the photocurable slurry.

[0057] In this embodiment, the photocurable resin includes a thermosensitive shape memory polymer, which is formed by the polymerization of a thermosensitive monomer, including N-isopropylacrylamide; the crosslinking agent includes N,N'-methylenebisacrylamide (MBA); and the photoinitiator includes 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0058] Step S3: Add the quantum dot tracer composition to the photocurable slurry, add antioxidants and hydrophobic modifiers to make the quantum dot tracer composition uniformly dispersed, and obtain the fluorescent layer 2 slurry.

[0059] In this embodiment, the photocurable slurry from step S2 and the modified red and green quantum dots obtained in step S1 are mixed at a mass ratio of 10:1 and dispersed using an ultrasonic instrument for 25 minutes to obtain a uniform fluorescent layer 2 slurry.

[0060] Step S4: Spray fluorescent layer 2 slurry onto the surface of substrate layer 1, and use a light curing light source to irradiate fluorescent layer 2 slurry to light-cur and coat the surface of substrate layer 1, thus obtaining substrate layer 1 coated with fluorescent layer 2.

[0061] In one embodiment, 60-100 mesh quartz sand (bulk density 1.2-1.6 g / cm³) is selected as the matrix layer 1 particles. 80 parts of quartz sand are placed in a forced-air drying oven and heated to 100°C. The mixture is then transferred to a sand mixing container, and 20 parts by weight of fluorescent layer 2 slurry is added. The mixture is stirred at 50 r / min for 20 min to coat the surface. The mixture is then irradiated under 120 mW / cm², 365 nm ultraviolet light for 20-30 min to photocur the fluorescent layer 2 slurry and coat the surface of the matrix layer 1, thus obtaining a matrix layer 1 coated with fluorescent layer 2. The thickness of fluorescent layer 2 is 1-100 μm.

[0062] Step S5: Immerse the substrate layer 1 coated with fluorescent layer 2 into the microgel solution, and deposit the outer layer of microgel on the surface of the substrate layer 1 coated with fluorescent layer 2 to obtain composite particles.

[0063] In this embodiment, acrylic acid (AA)-N-isopropylacrylamide (NIPAM)-dimethylaminoethyl methacrylate (DMAEMA) ternary copolymer microgel was used as a pH / mineralization dual-responsive hydrogel system to prepare a 5-20 w / w% pH / mineralization responsive microgel aqueous solution. Using a layer-by-layer self-assembly technique, the substrate layer 1, which is coated with fluorescent layer 2, was immersed in the solution, and a microgel coating was deposited on the surface of fluorescent layer 2 at 25-35℃ for 10-15 min, with the deposition thickness of the microgel coating controlled to be 100-500 nm.

[0064] Step S6: Dry, disperse, cool and sieve the composite particles to obtain fracturing proppant.

[0065] In this embodiment, the composite particles were placed in a 120°C drying oven and evaporated for 2.5 hours to remove residual moisture; then they were immersed in 50 ml of deionized water, dispersed using an ultrasonic instrument for 30 minutes, and passed through a 40-60 mesh sieve to obtain quantum dot fracturing proppant.

[0066] Six fracturing stages were performed on a horizontal well in a tight oil reservoir, resulting in six fracturing stages. Each stage used a different dual-wavelength coded proppant. The coding of the proppant was achieved by adjusting the composition of the fluorescent quantum dots. In this embodiment, the coding of the dual-wavelength fluorescent quantum dots for the six fracturing stages is as follows: Segment 1: 480nm / 532nm, Segment 2: 480nm / 625nm, Segment 3: 532nm / 650nm, Segment 4: 550nm / 625nm, Segment 5: 550nm / 650nm, Segment 6: 532nm / 680nm.

[0067] During fracturing, proppant was mixed with conventional ceramic aggregate at a ratio of 10% and injected into the target fracture segment along with the fracturing fluid. Six fracturing segments were obtained after fracturing. These segments were irradiated separately using a downhole ultraviolet fiber optic system (wavelength 365nm, power 120mW / cm²), and the flowback fluid spectral signal was monitored in real time using a handheld fluorescence spectrometer (detection accuracy 0.1ppb) on the surface. The contribution of each segment to the production was identified within 30 seconds (the third segment had the highest contribution rate, reaching 35%). Continuous monitoring for six months after fracturing showed that the proppant conductivity was maintained at 85%, the polymer residue in the formation fluid was <0.1mg / L, and the degradation rate reached 92%.

[0068] Example 4 According to the preparation method of fracturing proppant in Example 2, six proppants with unique codes were prepared by using three different emission wavelengths of quantum dots (450nm blue, 520nm green, and 650nm red) in different mass ratios of fluorescent quantum dots. Table 1 is the coding table for fracturing proppant, and the specific coding scheme is shown in Table 1:

[0069] Six types of coded proppant were injected into six fracturing sections of a horizontal well. Wellhead samples were taken continuously for 180 days post-fracturing, and fluorescence intensity at each wavelength was detected using a fluorescence spectrometer. Testing showed that the decoding accuracy of the six codes reached 99.2%, with an error of ≤1.5% in the production contribution percentage of each section. Continuous monitoring could be achieved without shutting in the well, representing a three-fold increase in efficiency compared to traditional production logging.

[0070] Example 5 This embodiment provides a fracturing proppant with quantum dot tracer function for oil and gas development, which includes, from the inside out, a matrix layer 1, a fluorescent layer 2 covering the matrix layer 1, and a microgel layer 3 covering the fluorescent layer 2; the fluorescent layer 2 includes a photocurable resin composition and a quantum dot tracer composition; the quantum dot tracer composition includes modified fluorescent quantum dots, which are obtained by grafting a silane coupling agent onto the surface of the fluorescent quantum dots, and the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane; the microgel layer 3 includes a pH / mineralization dual-responsive hydrogel system.

[0071] In this embodiment, the matrix layer 1, as a low-density, high-strength skeleton particle, accounts for 70% of the total weight of the fracturing proppant. The matrix layer 1 is selected from one or more of quartz sand, ceramsite, silicone resin microspheres or polymethyl methacrylate particles, with a particle size range of 50-200 mesh, a bulk density of 0.9-2 g / cm³, and a breakage rate of less than 10% in the 60MPa fracture resistance test.

[0072] In this embodiment, the mass ratio of silane coupling agent to fluorescent quantum dots is 1:1. The fluorescent quantum dots include carbon quantum dots with a particle size of 2-10 nm and an emission wavelength that is adjustable in the range of 450-680 nm.

[0073] In this embodiment, the photocurable resin composition includes a photocurable resin, a photoinitiator, and an active diluent; the photocurable resin includes a thermosensitive polymer formed by polymerizing a thermosensitive monomer, the thermosensitive monomer including N-isopropylacrylamide. In the photocurable resin composition, the photocurable resin is 50 parts by weight, the photoinitiator is 2 parts by weight, and the diluent is 10 parts by weight.

[0074] In this embodiment, the pH / mineralization dual-responsive hydrogel system includes an acrylic acid (AA)-N-isopropylacrylamide (NIPAM)-dimethylaminoethyl methacrylate (DMAEMA) ternary copolymer microgel.

[0075] In this embodiment, the thickness of the fluorescent layer 2 is 1 μm; the thickness of the microgel layer 3 is 100 nm.

[0076] In this embodiment, the matrix layer 1 accounts for 70% of the total weight of the fracturing proppant; the fluorescent layer 2 accounts for 25% of the total weight of the fracturing proppant; and the microgel layer 3 accounts for 5% of the total weight of the fracturing proppant.

[0077] Example 6 This embodiment provides a fracturing proppant with quantum dot tracer function for oil and gas development, which includes, from the inside out, a matrix layer 1, a fluorescent layer 2 covering the matrix layer 1, and a microgel layer 3 covering the fluorescent layer 2; the fluorescent layer 2 includes a photocurable resin composition and a quantum dot tracer composition; the quantum dot tracer composition includes modified fluorescent quantum dots, which are obtained by grafting a silane coupling agent onto the surface of the fluorescent quantum dots, and the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane; the microgel layer 3 includes a pH / mineralization dual-responsive hydrogel system.

[0078] In this embodiment, the matrix layer 1, as a low-density, high-strength skeleton particle, accounts for 70% of the total weight of the fracturing proppant. The matrix layer 1 is selected from ceramsite with a particle size range of 50-200 mesh, a bulk density of 0.9-2 g / cm³, and a breakage rate of less than 10% in the 60MPa fracture resistance test.

[0079] In this embodiment, the mass ratio of silane coupling agent to fluorescent quantum dots is 2:1. The fluorescent quantum dots include graphene quantum dots with a particle size of 2-10 nm and an emission wavelength that is adjustable in the range of 450-680 nm.

[0080] In this embodiment, the photocurable resin composition includes a photocurable resin, a photoinitiator, and an active diluent; the photocurable resin includes a thermosensitive polymer formed by polymerizing a thermosensitive monomer, the thermosensitive monomer including N-isopropylacrylamide. In the photocurable resin composition, the photocurable resin is 50 parts by weight, the photoinitiator is 2 parts by weight, and the diluent is 10 parts by weight.

[0081] In this embodiment, the pH / mineralization dual-responsive hydrogel system includes an acrylic acid (AA)-N-isopropylacrylamide (NIPAM)-dimethylaminoethyl methacrylate (DMAEMA) ternary copolymer microgel.

[0082] In this embodiment, the thickness of the fluorescent layer 2 is 100 μm; the thickness of the microgel layer 3 is 500 nm.

[0083] In this embodiment, the matrix layer 1 accounts for 90% of the total weight of the fracturing proppant; the fluorescent layer 2 accounts for 5% of the total weight of the fracturing proppant; and the microgel layer 3 accounts for 5% of the total weight of the fracturing proppant.

[0084] Example 7 This embodiment provides a fracturing proppant with quantum dot tracer function for oil and gas development, which includes, from the inside out, a matrix layer 1, a fluorescent layer 2 covering the matrix layer 1, and a microgel layer 3 covering the fluorescent layer 2; the fluorescent layer 2 includes a photocurable resin composition and a quantum dot tracer composition; the quantum dot tracer composition includes modified fluorescent quantum dots, which are obtained by grafting a silane coupling agent onto the surface of the fluorescent quantum dots, and the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane; the microgel layer 3 includes a pH / mineralization dual-responsive hydrogel system.

[0085] In this embodiment, the matrix layer 1, as a low-density, high-strength skeleton particle, accounts for 70% of the total weight of the fracturing proppant. The matrix layer 1 is selected from ceramsite with a particle size range of 50-200 mesh, a bulk density of 0.9-2 g / cm³, and a breakage rate of less than 10% in the 60MPa fracture resistance test.

[0086] In this embodiment, the mass ratio of silane coupling agent to fluorescent quantum dots is 2:1. The fluorescent quantum dots include graphene quantum dots with a particle size of 2-10 nm and an emission wavelength that is adjustable in the range of 450-680 nm.

[0087] In this embodiment, the photocurable resin composition includes a photocurable resin, a photoinitiator, and an active diluent; the photocurable resin includes a thermosensitive polymer formed by polymerizing a thermosensitive monomer, the thermosensitive monomer including N-isopropylacrylamide. In the photocurable resin composition, the photocurable resin is 70 parts by weight, the photoinitiator is 5 parts by weight, and the diluent is 20 parts by weight.

[0088] In this embodiment, the pH / mineralization dual-responsive hydrogel system includes an acrylic acid (AA)-N-isopropylacrylamide (NIPAM)-dimethylaminoethyl methacrylate (DMAEMA) ternary copolymer microgel.

[0089] In this embodiment, the thickness of the fluorescent layer 2 is 100 μm; the thickness of the microgel layer 3 is 500 nm.

[0090] In this embodiment, the matrix layer 1 accounts for 90% of the total weight of the fracturing proppant; the fluorescent layer 2 accounts for 9% of the total weight of the fracturing proppant; and the microgel layer 3 accounts for 1% of the total weight of the fracturing proppant.

[0091] Comparative Example 1 This comparative example provides a fracturing proppant, which, from the inside out, sequentially includes a matrix layer and a thermosetting fluorescent layer covering the matrix layer; the fluorescent layer includes a thermosetting system and a quantum dot system.

[0092] The matrix layer comprises 100 parts by weight of quartz sand; the thermosetting system comprises 60 parts by weight of epoxy resin (E-51), 8 parts by weight of curing agent (diethylenetriamine), and 15 parts by weight of diluent (dibutyl phthalate). The quantum dot system comprises 2 parts by weight of CdSe / ZnS quantum dots.

[0093] This comparative example provides a method for preparing fracturing proppant, comprising the following steps: Step S1, Slurry preparation: Mix 60 parts of E-51 epoxy resin, 8 parts of diethylenetriamine, and 15 parts of dibutyl phthalate, add 2 parts by weight of CdSe / ZnS quantum dots, 0.8 parts of antioxidant, and 4 parts of hydrophobic modifier, and disperse at 1500 r / min for 30 minutes. Step S2, heat curing: Preheat the quartz sand to 120°C, spray the slurry, and then transfer it to a 150°C oven for 6 hours to complete the curing. Step S3, post-processing: The composite particles are dried, dispersed, cooled, and sieved to obtain fracturing proppant.

[0094] Comparative Example 2 This comparative example provides a fracturing proppant, which, from the inside out, sequentially includes a matrix layer and a photocurable fluorescent layer covering the matrix layer.

[0095] The matrix layer comprises 100 parts of quartz sand; the photocurable fluorescent layer comprises 2 parts by weight of unmodified CdSe / ZnS quantum dots and 1.5 parts by weight of coupling agent, which is methyl vinyl dimethoxysilane.

[0096] The preparation method of the fracturing proppant in this comparative example is the same as the main steps in Example 5.

[0097] Comparative Example 3 This comparative example provides a fracturing proppant, which, from the inside out, sequentially includes a matrix layer and a photocurable quantum dot ink layer coated on the matrix layer. The photocurable quantum dot ink layer includes quantum dots modified with an unsaturated silane coupling agent, wherein the unsaturated silane coupling agent is methylvinyldimethoxysilane.

[0098] The preparation method of the fracturing proppant in this comparative example is the same as the main steps in Example 4.

[0099] The performance of the propped fracturing agents in Example 4 and Comparative Examples 1-3 was tested. Table 2 is the performance test table of the propped fracturing agents. Please refer to Table 2. The test results are shown in Table 2.

[0100]

[0101] Please refer to Table 2. The fracturing proppant of Example 4 has a coating peeling rate of only 10% after 7 days at a formation water flow rate of 0.2 m / s, which is much lower than the peeling rate of Comparative Examples 1-3. It is significantly superior to traditional proppant in terms of tracer accuracy (number of codes, response time, detection error), mechanical properties (anti-fracture, shape recovery, fracture repair), conductivity stability and fluorescence maintenance rate, and can meet the high-efficiency development requirements of multi-stage fracturing in unconventional oil and gas reservoirs.

[0102] Comparative Example 1 represents a traditional thermosetting epoxy resin coating process for quantum dots, with a peeling rate as high as 70%. Comparative Example 2 represents a process using photocuring but without chemical modification of the quantum dots, relying solely on physical mixing, resulting in a quantum dot peeling rate as high as 50%. Comparative Example 3 represents a process using commercially available photocurable quantum dot ink directly applied to pressure proppant; its coupling agent system differs from that of this invention. Comparative Example 3 uses existing photocurable ink directly, not a dedicated coupling agent system, demonstrating that not all combinations of photocurable resin systems and modified quantum dot systems are suitable for extreme downhole environments. Using general-purpose coupling agents such as methylvinyldimethoxysilane, the interfacial bonding strength with quantum dots and resin is insufficient in downhole environments. Furthermore, the quantum dot modification of the quantum dot ink does not consider temperature-sensitive response and pH / mineralization response functions, failing to achieve the crack repair and dynamic flow control of this embodiment.

[0103] This embodiment utilizes a quantum dot surface modification specifically designed for downhole environments. It combines a photocurable resin composition with a modified quantum dot composition and provides a three-layer composite structure with a pressure proppant. This systematically solves industry pain points of traditional tracer proppants, such as easy quantum dot detachment, difficulty in low-temperature curing, poor environmental stability, and limited functionality. It achieves integrated tracing, repair, and flow control, making it particularly suitable for long-term, accurate monitoring of low-temperature tight reservoirs. A systematic comparison of key performance indicators such as coating adhesion, environmental stability, fluorescence retention, and engineering applicability demonstrates the comprehensive advantages of this embodiment in low-temperature adaptability, quantum dot binding stability, and long-term coded tracing.

[0104] This invention is not limited to the above-described embodiments. If any modifications or variations to this invention do not depart from the spirit and scope of this invention, and if such modifications and variations fall within the scope of the claims and equivalent technologies of this invention, then this invention also intends to include such modifications and variations.

Claims

1. A fracturing proppant with quantum dot tracer function used in oil and gas development, characterized in that: From the inside out, it includes a matrix layer, a fluorescent layer covering the matrix layer, and a microgel layer covering the fluorescent layer; The fluorescent layer comprises a photocurable resin composition and a quantum dot tracer composition; The quantum dot tracer composition includes modified fluorescent quantum dots, which are obtained by grafting a silane coupling agent onto the surface of the fluorescent quantum dots, and the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane. The microgel layer comprises a pH / mineralization dual-responsive hydrogel system.

2. The fracturing proppant according to claim 1, characterized in that: The mass ratio of the silane coupling agent to the fluorescent quantum dots is 1:1 to 2:

1.

3. The fracturing proppant according to claim 1, characterized in that: The fluorescent quantum dots include at least one of CdSe / ZnS core-shell quantum dots, carbon quantum dots, graphene quantum dots, perovskite quantum dots, and CdTe / CdS quantum dots, with a particle size of 2-10 nm.

4. The fracturing proppant according to claim 1, characterized in that: The photocurable resin composition includes a photocurable resin, a photoinitiator, and an active diluent; the photocurable resin includes a thermosensitive polymer formed by the polymerization of a thermosensitive monomer, wherein the thermosensitive monomer includes at least one of N-isopropylacrylamide and poly(D,L-lactide-co-ε-caprolactone) acrylate.

5. The fracturing proppant according to claim 4, characterized in that: In the photocurable resin composition, the photocurable resin is 50-70 parts by weight, the photoinitiator is 2-5 parts by weight, and the diluent is 10-20 parts by weight.

6. The fracturing proppant according to claim 1, characterized in that: The pH / mineralization dual-responsive hydrogel system comprises an acrylic acid-N-isopropylacrylamide-dimethylaminoethyl methacrylate terpolymer microgel.

7. The fracturing proppant according to claim 1, characterized in that: The matrix layer accounts for 70-90% of the total weight of the fracturing proppant; the fluorescent layer accounts for 5-25% of the total weight of the fracturing proppant; and the microgel layer accounts for 1-5% of the total weight of the fracturing proppant.

8. The fracturing proppant according to claim 1, characterized in that: The thickness of the fluorescent layer is 1-100 μm; the thickness of the microgel layer is 100-500 nm.

9. The application of the fracturing proppant with quantum dot tracer function used in oil and gas development according to any one of claims 1-8 in monitoring the production capacity of multi-stage fracturing in horizontal wells, characterized in that: Different types of fracturing proppant with different codes are injected into different fracturing sections. By exciting the fluorescence of the fluorescent layer and detecting the returned drainage spectrum, the segmented production capacity of different fracturing sections can be identified.

10. A method for preparing the fracturing proppant according to any one of claims 1-8, characterized in that, Includes the following steps: Fluorescent quantum dots are dispersed in a solvent, a silane coupling agent is added, the mixture is stirred, centrifuged, and dried. The silane coupling agent is γ-methacryloxypropyltrimethoxysilane, to obtain quantum dot tracer composition particles. A photocurable resin, a photoinitiator, and a reactive diluent are mixed to obtain a photocurable slurry; Quantum dot tracer composition particles are added to a photocurable slurry, along with antioxidants and hydrophobic modifiers, to ensure uniform dispersion of the quantum dot tracer composition particles, thereby obtaining a fluorescent layer slurry. A fluorescent layer slurry is sprayed onto the surface of the substrate layer, and then the fluorescent layer slurry is irradiated with a light curing light source to cure the fluorescent layer slurry and coat the surface of the substrate layer, thus obtaining a substrate layer coated with a fluorescent layer. The substrate layer coated with a fluorescent layer is immersed in a microgel solution, and a microgel outer layer is deposited on the surface of the substrate layer particles coated with the fluorescent layer to obtain composite particles. The composite particles are dried, dispersed, cooled, and sieved to obtain the fracturing proppant.

Images