A high-strength ceramic proppant and a method of making the same

Abstract

The application relates to the technical field of fracturing proppants, in particular to a high-strength ceramsite proppant and a preparation method thereof. Aluminous soil, manganese powder, potassium feldspar and dolomite are mixed, crushed and ball milled to obtain mineral powder; the mineral powder is granulated, screened, dried, secondarily screened, sintered and cooled to obtain ceramsite; the ceramsite is preheated, modified hyperbranched epoxy resin, amino-terminated polyester microspheres and a curing agent are added, and the mixture is cured and cooled to obtain a finished product. The ceramsite proppant finished product prepared by the application has excellent hydrophobic and oleophobic properties, strength and toughness, and therefore has a wide application prospect in the technical field of fracturing proppants.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fracturing proppants, in particular to a high-strength ceramic proppant and a preparation method thereof. BACKGROUND

[0002] In the modern industry and energy field, ceramic proppants have shown an undeniable value due to their unique performance and wide application. In the field of oil exploitation, ceramic proppants play a key role. With the gradual advancement of oil exploitation to deep and complex formations, traditional proppants are prone to breakage and deformation under high strength and high closure pressure, resulting in a decrease in fracture conductivity. Ceramic proppants, however, have characteristics such as high strength, low density, high roundness and sphericity, etc., and can maintain good morphology under high pressure environment, effectively supporting the fractures formed by fracturing, allowing oil and gas to flow more smoothly into the wellbore, and improving the production and recovery rate of oil and gas wells. In the development of unconventional oil and gas resources such as shale gas, ceramic proppants are indispensable and provide strong support for the protection of national energy security. From the perspective of environmental protection, ceramic proppants can be produced using industrial waste such as fly ash and clay as raw materials, not only reducing the pollution of waste to the environment, but also realizing the recycling of resources, in line with the concept of sustainable development. Moreover, during use, ceramic proppants have stable performance and do not pollute the formation and underground water, helping to protect the ecological environment.

[0003] However, in the process of oil and gas exploitation, the fluid composition in the reservoir is complex, containing oil, water, etc. The surface of ceramic proppants is easily infiltrated by oil and water. After being infiltrated, oil droplets or water droplets will adhere to the surface of the proppants, which will increase the adhesion between the proppants, leading to uneven distribution of the proppants in the fractures, reducing the conductivity of the fractures, and further affecting the flow of oil and gas and the efficiency of exploitation. Therefore, the hydrophobic and oleophobic properties of the proppant surface are needed to repel oil and water, maintain the dispersibility and fluidity of the proppants, and allow oil and gas to flow more smoothly through the fractures filled with proppants, improving the production of oil and gas wells. In addition, the hydrophobic and oleophobic surface can also reduce the contact between the proppants and corrosive substances in the formation, prolonging the service life of the proppants. In addition, ceramic proppants have to withstand extremely high pressure downhole. In fracturing operations, the formation closure pressure will be applied to the proppants. If the strength and toughness of the proppants are insufficient, they are prone to breakage. Broken proppants will block the fracture channel, reducing the effective flow area of the fracture and seriously affecting the exploitation of oil and gas. Therefore, it is necessary to improve the strength and toughness of the proppants so that they can maintain their integrity in a high-pressure environment, continuously and effectively support the fractures, and ensure that the fractures have good conductivity for a long time.

[0004] In order to overcome the defects of the prior art, the present application provides a high-strength ceramic proppant and a preparation method thereof. SUMMARY

[0005] The present application aims to provide a high-strength ceramic proppant and a preparation method thereof to solve the problems in the prior art.

[0006] To achieve the above-mentioned object, the present application provides the following technical solutions.

[0007] The preparation method of the high-strength ceramic proppant comprises the following steps: mixing bauxite, manganese powder, potassium feldspar and dolomite, crushing and ball milling to obtain a mineral powder; granulating, screening, drying, secondary screening, sintering and cooling the mineral powder to obtain ceramic particles; preheating the ceramic particles, adding modified hyperbranched epoxy resin, amino-terminated polyester microspheres and a curing agent, and curing and cooling to obtain a finished product.

[0008] More preferably, when the ceramic particles are preheated, the temperature is 130-150 DEG C and the time is 1-2 h; the curing parameters are as follows: the curing temperature is 120-130 DEG C and the curing time is 7-8 h; the particle size of the mineral powder is 400-450 mesh; the drying temperature is 200-300 DEG C; the sintering temperature is 1200-1300 DEG C; and the particle size of the finished ceramic proppant is 30-50 mesh.

[0009] More preferably, the content of each component of the mineral powder is as follows: 70-80 parts by mass of bauxite, 4-5 parts by mass of manganese powder, 10-12 parts by mass of potassium feldspar and 4-5 parts by mass of dolomite; and the content of each component of the ceramic proppant is as follows: 85-95 parts by mass of ceramic particles, 10-15 parts by mass of modified hyperbranched epoxy resin, 3-5 parts by mass of amino-terminated polyester microspheres and 1-2 parts by mass of a curing agent.

[0010] More preferably, the preparation process of the modified hyperbranched epoxy resin is as follows:

[0011] Step S1: mixing acryloyl chloride, cuprous chloride and n-hexane, uniformly mixing, heating to 50-55 DEG C, slowly adding 2,2,2-trifluoroethanol and 4-dimethylaminopyridine, gradually heating to 60-65 DEG C after the addition is completed, continuously reacting for 5-6 h, cooling, neutralizing, washing and drying after the reaction is completed to obtain an intermediate product; mixing the intermediate product, sodium tungstate, methyltrioctylammonium chloride, hydrogen peroxide and phosphoric acid, refluxing at 60-70 DEG C for 15-20 h, and extracting, drying and rotary evaporating after the reaction is completed to obtain an epoxidized hydrophobic monomer;

[0012] Step S2: mixing sebacic acid and diethylene glycol, continuously heating to 130-140 DEG C, starting to stir, continuously heating to 175-185 DEG C, and incubating for 5-6 h, and cooling and drying after the reaction is completed to obtain a hydroxyl-terminated polyester;

[0013] Step S3: Bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, and epoxidized hydrophobic monomer are mixed uniformly, then a catalyst is added, and reflux reaction is carried out at 90-95 DEG C for 8-10 h; after the reaction is completed, cooling, washing, rotary evaporation, and vacuum drying are carried out to obtain the modified hyperbranched epoxy resin.

[0014] More preferably, in step S1, the content of each component of the epoxidized hydrophobic monomer is as follows: 3.5-4.5 parts of acryloyl chloride, 0.04-0.05 parts of cuprous chloride, 3-4 parts of n-hexane, 3.5-4.0 parts of 2,2,2-trifluoroethanol, 0.04-0.05 parts of 4-dimethylaminopyridine, 0.25-0.30 parts of sodium tungstate, 0.13-0.15 parts of methyltrioctylammonium chloride, 8.5-9.0 parts of 8wt% hydrogen peroxide, and 3.0-3.2 parts of 85wt% phosphoric acid.

[0015] More preferably, in step S2, the molar ratio of sebacic acid to diethylene glycol is 1.0: (1.2-1.3).

[0016] More preferably, in step S3, the mass ratio of bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer, and catalyst is 1: (2.0-2.5):3: (3.5-4.0): (0.04-0.05); the catalyst is tetrabutylammonium bromide.

[0017] More preferably, the preparation process of the amino-terminated polyester microspheres is as follows: tripropyleneglycol diacrylate, acetonitrile, and piperazine are mixed, then the mixture is stirred for 30-40 min after being sealed, stirring is carried out uniformly, then reaction is carried out at 2-4 DEG C for 12-14 h, and after the reaction is completed, centrifugation, washing, and drying are carried out to obtain the amino-terminated polyester microspheres.

[0018] More preferably, the molar ratio of tripropyleneglycol diacrylate to piperazine is 1: (1.5-1.7); the amount of tripropyleneglycol diacrylate and piperazine in the reaction system is 5-8wt%.

[0019] The beneficial effects of the present application are as follows:

[0020] The present application has the characteristics that substitution reaction occurs by adding acryloyl chloride and 2,2,2-trifluoroethanol to obtain an intermediate product with carbon-carbon double bonds; the intermediate product, sodium tungstate, methyltrioctylammonium chloride, hydrogen peroxide, and phosphoric acid are mixed, reflux reaction is carried out, olefin epoxidation reaction occurs, and an epoxidized hydrophobic monomer is obtained. Sebacic acid and diethylene glycol are mixed, polycondensation reaction occurs, and a hydroxyl-terminated polyester is obtained. Bisphenol A, the hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, and the epoxidized hydrophobic monomer are mixed uniformly, reflux reaction is carried out under the action of a catalyst, and a modified hyperbranched epoxy resin is obtained.

[0021] The fluorine atom in the epoxidized hydrophobic monomer has very high electronegativity, so when the fluorine atom is introduced into the molecular structure, the fluorine-containing segment tends to migrate and enrich to the material surface, forming a layer of low surface energy fluoride on the material surface, thereby effectively reducing the affinity of the material surface with water and oil, and imparting excellent hydrophobic and oleophobic properties to the modified hyperbranched epoxy resin. Bisphenol A is a commonly used raw material in the synthesis of epoxy resins, and its molecular structure contains a benzene ring, which has a rigid structure that can improve the rigidity and stability of the molecular chain. In the modified hyperbranched epoxy resin, the molecular chain segments formed by bisphenol A participating in the reaction can increase the hardness and strength of the resin. Trimethylolpropane triglycidyl ether has three epoxy groups, and in the subsequent curing reaction, these epoxy groups can undergo crosslinking reactions with other components to form a highly crosslinked three-dimensional network structure. This crosslinked structure can effectively transmit stress and prevent crack propagation, thereby improving the strength of the material. In addition, the hydroxyl-terminated polyester molecular chain synthesized from sebacic acid and diethylene glycol has a certain flexibility. In the modified hyperbranched epoxy resin, the flexible segment of the hydroxyl-terminated polyester can act as a toughening agent and be embedded in the highly crosslinked network structure. When the material is subjected to external force impact, these flexible segments can deform to a certain extent, absorbing and dissipating energy, thereby improving the toughness of the material. In addition, the hyperbranched structure synthesized from the above raw materials has a large number of branches and terminal groups. The synergistic effect of the flexible hydroxyl-terminated polyester segment and the hyperbranched structure allows the modified hyperbranched epoxy resin to absorb and disperse energy through molecular chain deformation and movement when subjected to stress.

[0022] The application is characterized in that tripropylene glycol dipropyl acrylate, acetonitrile and piperazine are mixed, and an amine-ene nucleophilic addition reaction is carried out at low temperature to obtain amino-terminated polyester microspheres. The tripropylene glycol part provides a certain molecular chain length and flexible connection structure. These flexible segments can bend and stretch to a certain extent when the microspheres are subjected to external force, absorbing and dissipating energy. When the microspheres are impacted or stretched, the deformation of the flexible segments can relieve stress and prevent brittle fracture of the microspheres, thereby improving the toughness of the microspheres. In addition, by setting the reaction molar ratio of tripropylene glycol dipropyl acrylate and piperazine to 1:(1.5-1.7), the piperazine is relatively excessive in the system, and the amino-terminated structure is obtained, so that the amino-terminated polyester microspheres can be effectively mixed, cured and crosslinked with the modified hyperbranched epoxy resin in the subsequent process. In addition, multiple tripropylene glycol dipropyl acrylate molecules are connected together to form a polyester backbone structure, which provides basic skeletal support for the microspheres and helps to improve the strength of the microspheres. Piperazine molecules contain two secondary amine groups, which have strong nucleophilicity and can undergo nucleophilic addition reaction with the acrylate groups of tripropylene glycol dipropyl acrylate. Piperazine acts as a crosslinking agent to connect multiple tripropylene glycol dipropyl acrylate molecules to form a three-dimensional network structure. This crosslinking structure can effectively transfer stress and prevent deformation and damage of the microspheres under stress, thereby improving the strength of the microspheres.

[0023] The application is characterized in that bauxite, manganese powder, potassium feldspar and dolomite are mixed, crushed and ball milled to obtain a mineral powder; the mineral powder is granulated, screened, dried, secondarily screened, sintered and cooled to obtain ceramsite; the ceramsite is preheated, and then modified hyperbranched epoxy resin, amino-terminated polyester microspheres and a curing agent are added to obtain a finished product. The application uses 100% mineral powder for production. This measure effectively avoids the high-temperature calcination link in the traditional process, and instead uses tail gas waste heat to dry the mineral powder at a low temperature of 200-300 DEG C. The low-temperature drying process has important resource protection significance. It significantly reduces the burning loss rate of raw materials in the processing process by accurately controlling the temperature, ensures efficient use of resources, and meets the strategic requirements of resource rational allocation and sustainable development. In addition, the application uses a sintering method using clean energy natural gas as fuel. This method greatly improves energy utilization efficiency, greatly reduces energy consumption, significantly reduces pollutant emissions during production, effectively reduces the negative impact on the environment, and sets an example for the green development of the industry.

[0024] In summary, the added bauxite and other raw materials are sintered to form a stable skeleton, the modified hyperbranched epoxy resin contains rigid structures and crosslinking networks, and the amino-terminated polyester microspheres have a filling and reinforcing effect. The sintering makes the minerals form compact crystals, and the solidification makes the components tightly combined. The fluorine-containing structure of the modified hyperbranched epoxy resin endows hydrophobic and oleophobic properties, and the flexible segments and microspheres synergistically improve the toughness, and the overall structure effectively transmits stress to enhance strength. Therefore, the proppant has a broad application prospect in the field of fracturing proppant technology. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] Raw material sources:

[0027] The bauxite was provided by Hebei Hengguang Mineral Products Co., Ltd., with a particle size of 325 mesh; the manganese powder was provided by Qinghe County Xingxin New Material Technology Co., Ltd., with a particle size of 300 mesh; the potassium feldspar was provided by Hebei Jiyang Mineral Products Co., Ltd., with a specification of 325 mesh; the dolomite was provided by Lingshou County Zhansheng Mineral Products Co., Ltd., with a particle size of 30 mesh; the curing agent was polyetheramine D230; in terms of mass fraction, one part was 1 g.

[0028] Example 1: Step S1: 4.5 g of acryloyl chloride, 0.05 g of cuprous chloride and 4 g of n-hexane were mixed, uniformly mixed, and then heated to 55℃, and then 4.0 g of 2,2,2-trifluoroethanol and 0.05 g of 4-dimethylaminopyridine were slowly added, and after the addition was completed, the temperature was gradually increased to 65℃, and the reaction was continued for 6 h. After the reaction was completed, the mixture was cooled, neutralized, washed and dried to obtain an intermediate product. Then the intermediate product, 0.30 g of sodium tungstate, 0.15 g of methyltrioctylammonium chloride, 9.0 g of 8 wt% hydrogen peroxide, and 3.2 g of 85 wt% phosphoric acid were mixed and refluxed at 70℃ for 20 h. After the reaction was completed, the mixture was extracted, dried and rotary evaporated to obtain an epoxidized hydrophobic monomer.

[0029] Step S2: Sebacic acid and diethylene glycol were mixed and continuously heated to 140℃, and then the stirring reaction was started. Then the temperature was continuously increased to 185℃, and the reaction was kept for 6 h. After the reaction was completed, the mixture was cooled and dried to obtain a hydroxyl-terminated polyester. The reaction molar ratio of sebacic acid to diethylene glycol was 1.0:1.25.

[0030] Step S3: Bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer were mixed uniformly, then tetrabutylammonium bromide was added, and refluxed at 95℃ for 10h. After the reaction was completed, it was cooled, washed, rotary evaporated, and vacuum dried to obtain the modified hyperbranched epoxy resin; the mass ratio of bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer, and tetrabutylammonium bromide was 1:2.3:3:3.7:0.045;

[0031] Step S4: Tripropyleneglycol diacrylate, acetonitrile, and piperazine were mixed and stirred for 40min at 4℃ for 14h after uniform stirring. After the reaction was completed, it was centrifuged, washed, and dried to obtain the amino-terminated polyester microspheres; the molar ratio of tripropyleneglycol diacrylate and piperazine was 1:1.6; the amount of tripropyleneglycol diacrylate and piperazine in the reaction system was 6wt%;

[0032] Step S5: 80g bauxite, 5g manganese powder, 12g potassium feldspar, and 5g dolomite were mixed, crushed, and ball milled to obtain a mineral powder; the mineral powder was then granulated, sieved, dried, secondarily sieved, sintered, and cooled to obtain ceramsite; 95g ceramsite was preheated at 150℃ for 2h, then 15g modified hyperbranched epoxy resin, 5g amino-terminated polyester microspheres, and 2g curing agent were added, and cured at 130℃ for 8h and cooled to obtain the finished product; the particle size of the mineral powder was 400 mesh; the drying temperature was 300℃; and the sintering temperature was 1300℃.

[0033] Example 2: Step S1: 4.5g acryloyl chloride, 0.05g cuprous chloride, and 4g n-hexane were mixed, uniformly mixed, and then heated to 53℃; then 4.0g 2,2,2-trifluoroethanol and 0.05g 4-dimethylaminopyridine were slowly added; after the addition was completed, the temperature was gradually increased to 63℃, and the reaction was continued for 5.5h; after the reaction was completed, it was cooled, neutralized, washed, and dried to obtain an intermediate product; then the intermediate product, 0.30g sodium tungstate, 0.15g methyltrioctylammonium chloride, 9.0g 8wt% hydrogen peroxide, and 3.2g 85wt% phosphoric acid were mixed, and refluxed at 65℃ for 17h; after the reaction was completed, it was extracted, dried, and rotary evaporated to obtain an epoxidized hydrophobic monomer;

[0034] Step S2: Sebacic acid and diethylene glycol were mixed, and the temperature was continuously increased to 135℃; stirring was started, and then the temperature was continuously increased to 180℃; the reaction was continued for 5.5h; after the reaction was completed, it was cooled and dried to obtain a hydroxyl-terminated polyester; the molar ratio of sebacic acid and diethylene glycol was 1.0:1.25;

[0035] Step S3: Bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer were mixed uniformly, then a catalyst was added, and refluxed at 92℃ for 9h. After the reaction was completed, it was cooled, washed, rotary evaporated, and vacuum dried to obtain the modified hyperbranched epoxy resin; the mass ratio of bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer, and tetrabutylammonium bromide was 1:2.3:3:3.7:0.045;

[0036] Step S4: Tripropyleneglycol diacrylate, acetonitrile, and piperazine were mixed, sealed, and stirred for 35min. After being stirred uniformly, it was reacted at 3℃ for 13h. After the reaction was completed, it was centrifuged, washed, and dried to obtain the amino-terminated polyester microspheres; the molar ratio of tripropyleneglycol diacrylate and piperazine was 1:1.6; the amount of tripropyleneglycol diacrylate and piperazine in the reaction system was 6wt%;

[0037] Step S5: 80g bauxite, 5g manganese powder, 12g potassium feldspar, and 5g dolomite were mixed, crushed, and ball milled to obtain a mineral powder; the mineral powder was then granulated, sieved, dried, secondarily sieved, sintered, and cooled to obtain ceramsite; 95g ceramsite was preheated at 140℃ for 1.5h, then 15g modified hyperbranched epoxy resin, 5g amino-terminated polyester microspheres, and 2g curing agent were added, and cured at 125℃ for 7.5h and cooled to obtain the finished product; the particle size of the mineral powder was 400 mesh; the drying temperature was 250℃; and the sintering temperature was 1250℃.

[0038] Example 3: Step S1: 4.5g acryloyl chloride, 0.05g cuprous chloride, and 4g n-hexane were mixed, uniformly mixed, and then heated to 50℃; then 4.0g 2,2,2-trifluoroethanol and 0.05g 4-dimethylaminopyridine were slowly added; after the addition was completed, the temperature was gradually increased to 60℃, and the reaction was continued for 5h; after the reaction was completed, it was cooled, neutralized, washed, and dried to obtain an intermediate product; then the intermediate product, 0.30g sodium tungstate, 0.15g methyltrioctylammonium chloride, 9.0g 8wt% hydrogen peroxide, and 3.2g 85wt% phosphoric acid were mixed, and refluxed at 60℃ for 15h; after the reaction was completed, it was extracted, dried, and rotary evaporated to obtain the epoxidized hydrophobic monomer;

[0039] Step S2: Sebacic acid and diethylene glycol were mixed, and the temperature was continuously increased to 130℃; stirring was started, and then the temperature was continuously increased to 175℃; the reaction was continued for 5h; after the reaction was completed, it was cooled and dried to obtain the hydroxyl-terminated polyester; the molar ratio of sebacic acid and diethylene glycol was 1.0:1.25;

[0040] Step S3: Bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer were mixed uniformly, then catalyst was added, and the mixture was refluxed at 90°C for 8h. After the reaction was completed, the mixture was cooled, washed, rotary evaporated, and vacuum dried to obtain the modified hyperbranched epoxy resin; the mass ratio of bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer, and tetrabutylammonium bromide was 1:2.3:3:3.7:0.045;

[0041] Step S4: Dipropylene glycol diacrylate, acetonitrile, and piperazine were mixed, and stirred for 30min after sealing. After stirring uniformly, the mixture was reacted at 2°C for 12h. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the amino-terminated polyester microspheres; the molar ratio of dipropylene glycol diacrylate and piperazine was 1:1.6; the amount of dipropylene glycol diacrylate and piperazine in the reaction system was 6wt%;

[0042] Step S5: 80g bauxite, 5g manganese powder, 12g potassium feldspar, and 5g dolomite were mixed, crushed, and ball milled to obtain a mineral powder. The mineral powder was granulated, sieved, dried, secondarily sieved, sintered, and cooled to obtain ceramsite. 95g ceramsite was preheated at 130°C for 1h, then 15g modified hyperbranched epoxy resin, 5g amino-terminated polyester microspheres, and 2g curing agent were added, and the mixture was cured at 120°C for 7h and cooled to obtain the finished product; the particle size of the mineral powder was 400 mesh; the drying temperature was 200°C; and the sintering temperature was 1200°C.

[0043] Comparative Example 1: The epoxidized hydrophobic monomer was removed, and the remaining steps were the same as those in Example 1. The specific steps were as follows: Step S1: Sebacic acid and diethylene glycol were mixed, and the temperature was continuously increased to 140°C. Stirring was started, and the temperature was continuously increased to 185°C. The mixture was incubated for 6h. After the reaction was completed, the mixture was cooled and dried to obtain the hydroxyl-terminated polyester; the molar ratio of sebacic acid and diethylene glycol was 1.0:1.25;

[0044] Step S2: Bisphenol A, hydroxyl-terminated polyester, and trimethylolpropane triglycidyl ether were mixed uniformly, then catalyst was added, and the mixture was refluxed at 95°C for 10h. After the reaction was completed, the mixture was cooled, washed, rotary evaporated, and vacuum dried to obtain the modified hyperbranched epoxy resin; the mass ratio of bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, and tetrabutylammonium bromide was 1:2.3:3:0.045;

[0045] Step S3: Dipropylene glycol diacrylate, acetonitrile, and piperazine were mixed, and stirred for 40min after sealing. After stirring uniformly, the mixture was reacted at 4°C for 14h. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the amino-terminated polyester microspheres; the molar ratio of dipropylene glycol diacrylate and piperazine was 1:1.6; the amount of dipropylene glycol diacrylate and piperazine in the reaction system was 6wt%;

[0046] Step S4: 80 g bauxite, 5 g manganese powder, 12 g potassium feldspar, 5 g dolomite were mixed, crushed, ball milled to obtain a mineral powder; the mineral powder was then granulated, screened, dried, rescreened, sintered, and cooled to obtain ceramsite; 95 g of the ceramsite was preheated at 150 °C for 2 h, then 15 g of the modified hyperbranched epoxy resin, 5 g of the amino-terminated polyester microspheres, and 2 g of the curing agent were added, and the mixture was cured at 130 °C for 8 h and then cooled to obtain the finished product; the particle size of the mineral powder was 400 mesh; the drying temperature was 300 °C; and the sintering temperature was 1300 °C.

[0047] Comparative Example 2: The hydroxyl-terminated polyester was removed, and the rest was the same as in Example 1, and the specific steps were as follows: Step S1: 4.5 g of acryloyl chloride, 0.05 g of cuprous chloride, and 4 g of n-hexane were mixed, and after being uniformly mixed, the mixture was heated to 55 °C, then 4.0 g of 2,2,2-trifluoroethanol and 0.05 g of 4-dimethylaminopyridine were slowly added, after the addition was completed, the temperature was gradually increased to 65 °C, and the reaction was continued for 6 h; after the reaction was completed, the mixture was cooled, neutralized, washed, and dried to obtain an intermediate product; the intermediate product, 0.30 g of sodium tungstate, 0.15 g of methyltrioctylammonium chloride, 9.0 g of 8 wt% hydrogen peroxide, and 3.2 g of 85 wt% phosphoric acid were mixed, and the mixture was refluxed at 70 °C for 20 h; after the reaction was completed, the mixture was extracted, dried, and rotary evaporated to obtain an epoxidized hydrophobic monomer;

[0048] Step S2: Bisphenol A, trimethylolpropane triglycidyl ether, and the epoxidized hydrophobic monomer were uniformly mixed, then a catalyst was added, and the mixture was refluxed at 95 °C for 10 h; after the reaction was completed, the mixture was cooled, washed, rotary evaporated, and vacuum dried to obtain a modified hyperbranched epoxy resin; the reaction mass ratio of bisphenol A, trimethylolpropane triglycidyl ether, the epoxidized hydrophobic monomer, and tetrabutylammonium bromide was 1:3:3.7:0.045;

[0049] Step S3: Dipropargyl glycol diacrylate, acetonitrile, and piperazine were mixed, sealed, and stirred for 40 min; after being uniformly stirred, the mixture was reacted at 4 °C for 14 h; after the reaction was completed, the mixture was centrifuged, washed, and dried to obtain amino-terminated polyester microspheres; the reaction molar ratio of dipropargyl glycol diacrylate to piperazine was 1:1.6; the amount of dipropargyl glycol diacrylate and piperazine in the reaction system was 6 wt%;

[0050] Step S4: 80 g bauxite, 5 g manganese powder, 12 g potassium feldspar, 5 g dolomite were mixed, crushed, ball milled to obtain a mineral powder; the mineral powder was then granulated, screened, dried, rescreened, sintered, and cooled to obtain ceramsite; 95 g of the ceramsite was preheated at 150 °C for 2 h, then 15 g of the modified hyperbranched epoxy resin, 5 g of the amino-terminated polyester microspheres, and 2 g of the curing agent were added, and the mixture was cured at 130 °C for 8 h and then cooled to obtain the finished product; the particle size of the mineral powder was 400 mesh; the drying temperature was 300 °C; and the sintering temperature was 1300 °C.

[0051] Comparative Example 3: The amino-terminated polyester microspheres were removed, and the rest was the same as Example 1, and the specific steps were as follows: Step S1: 4.5 g of acryloyl chloride, 0.05 g of cuprous chloride, 4 g of n-hexane were mixed, after uniform mixing, the temperature was raised to 55℃, then 4.0 g of 2,2,2-trifluoroethanol and 0.05 g of 4-dimethylaminopyridine were slowly added, after the addition was completed, the temperature was gradually raised to 65℃, and the reaction was continued for 6 h, after the reaction was completed, it was cooled, neutralized, washed, and dried to obtain an intermediate product; then the intermediate product, 0.30 g of sodium tungstate, 0.15 g of methyltrioctylammonium chloride, 9.0 g of 8 wt% hydrogen peroxide, and 3.2 g of 85 wt% phosphoric acid were mixed and refluxed at 70℃ for 20 h, after the reaction was completed, it was extracted, dried, and rotary evaporated to obtain an epoxidized hydrophobic monomer;

[0052] Step S2: Sebacic acid and diethylene glycol were mixed and continuously heated to 140℃, stirring was started, then the temperature was continuously raised to 185℃, and the reaction was kept for 6 h, after the reaction was completed, it was cooled and dried to obtain a hydroxyl-terminated polyester; the reaction molar ratio of sebacic acid to diethylene glycol was 1.0:1.25;

[0053] Step S3: Bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, and epoxidized hydrophobic monomer were uniformly mixed, then a catalyst was added, and the mixture was refluxed at 95℃ for 10 h, after the reaction was completed, it was cooled, washed, rotary evaporated, and vacuum dried to obtain a modified hyperbranched epoxy resin; the reaction mass ratio of bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer, and tetrabutylammonium bromide was 1:2.3:3:3.7:0.045;

[0054] Step S4: 80 g of bauxite, 5 g of manganese powder, 12 g of potassium feldspar, and 5 g of dolomite were mixed, crushed, and ball milled to obtain a mineral powder; then the mineral powder was granulated, screened, dried, secondarily screened, sintered, and cooled to obtain a ceramsite; 95 g of the ceramsite was preheated at 150℃ for 2 h, then 15 g of the modified hyperbranched epoxy resin and 2 g of a curing agent were added, and the mixture was cured at 130℃ for 8 h and cooled to obtain a finished product; the particle size of the mineral powder was 400 mesh; the drying temperature was 300℃; and the sintering temperature was 1300℃.

[0055] Detection test:

[0056] Adsorption test: The finished ceramsite proppant prepared in the application was used as a sample, the sample was immersed in a fracturing fluid for 50 h, the mass of the sample before and after immersion was weighed, and then the data was substituted into the formula (mass after immersion-mass before immersion) / mass before immersion x 100%=weight increase rate to obtain the weight increase rate; wherein the fracturing fluid was according to the formula disclosed in CN117887441B.

[0057] Mechanical property test: the finished ceramic proppant prepared by the application is used as a sample, and the crushing rate of the sample under a closed pressure of 103 MPa is tested according to SY / T 17125-2019 "Fracturing fluid proppant performance index and evaluation test method". The results are as follows:

[0058]

[0059] Conclusion: the amount of examples 1-3 is unchanged, only the reaction parameters are modified. From the experimental data, the performance of the sample does not change significantly.

[0060] Comparative example 1: remove the epoxidized hydrophobic monomer, the rest is the same as example 1, from the experimental data, compared with example 1, the weight gain rate increases to 9.3%, and the crushing rate increases to 8.5%, the reason is that the epoxidized hydrophobic monomer contains a large amount of fluorine element, and the fluorine atom has very high electronegativity, so the fluorine-containing group has very low surface energy, so the sample has excellent hydrophobic and oleophobic properties. Therefore, after removing the epoxidized hydrophobic monomer, the weight gain rate increases significantly.

[0061] Comparative example 2: remove the hydroxyl-terminated polyester, the rest is the same as example 1, from the experimental data, compared with example 1, the weight gain rate increases to 3.1%, and the crushing rate increases to 11.7%, the reason is that the flexible segment of the hydroxyl-terminated polyester can be used as a toughening agent and embedded in the highly cross-linked network structure, thereby improving the toughness of the material. Therefore, after removing the hydroxyl-terminated polyester, the crushing rate increases.

[0062] Comparative example 3: remove the amino-terminated polyester microspheres, the rest is the same as example 1, from the experimental data, compared with example 1, the weight gain rate increases to 2.5%, and the crushing rate increases to 10.2%, the reason is that on the one hand, the flexible segment in the amino-terminated polyester microspheres can bend and stretch to a certain extent when the microspheres are subjected to external force, absorbing and dissipating energy. On the other hand, by setting the reaction molar ratio of dipropylene glycol diacrylate and piperazine to 1: (1.5-1.7), the piperazine is relatively excessive in the system, and the amino-terminated structure is obtained, so the amino-terminated polyester microspheres can be effectively mixed, cured and cross-linked with the modified hyperbranched epoxy resin in the subsequent process. This cross-linked structure can effectively transfer stress and prevent the microspheres from deforming and breaking when subjected to stress, thereby improving the strength of the microspheres. Therefore, after removing the amino-terminated polyester microspheres, the crushing rate increases.

[0063] It is to be noted that, in the present text, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0064] Finally, it should be noted that the above-mentioned only constitutes preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications, equivalent substitutions, improvements and the like of the technical solutions described in the foregoing embodiments can still be made. Any modifications, equivalent substitutions, improvements and the like made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for preparing a high-strength ceramic proppant, characterized in that: The process includes the following steps: mixing bauxite, manganese powder, potassium feldspar, and dolomite, crushing and ball milling to obtain mineral powder; then granulating, sieving, drying, secondary sieving, sintering, and cooling the mineral powder to obtain ceramsite; preheating the ceramsite, then adding modified hyperbranched epoxy resin, amino-terminated polyester microspheres, and a curing agent, followed by curing and cooling to obtain the finished product; The preparation process of the modified hyperbranched epoxy resin is as follows: Step S1: Acryloyl chloride, cuprous chloride, and n-hexane are mixed and heated to 50-55℃. Then, 2,2,2-trifluoroethanol and 4-dimethylaminopyridine are slowly added. After the addition is complete, the temperature is gradually increased to 60-65℃ and the reaction is continued for 5-6 hours. After the reaction is completed, the mixture is cooled, neutralized, washed, and dried to obtain an intermediate product. The intermediate product, sodium tungstate, methyltrioctylammonium chloride, hydrogen peroxide, and phosphoric acid are mixed and refluxed at 60-70℃ for 15-20 hours. After the reaction is completed, the mixture is extracted, dried, and rotary evaporated to obtain an epoxidized hydrophobic monomer. Step S2: Mix sebacic acid and diethylene glycol, continuously heat to 130-140℃, start stirring the reaction, and then continue heating to 175-185℃, keep the reaction at this temperature for 5-6 hours. After the reaction is completed, cool and dry to obtain hydroxyl-terminated polyester. Step S3: Mix bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, and epoxidized hydrophobic monomer evenly, then add catalyst, and reflux at 90-95℃ for 8-10 hours. After the reaction is completed, cool, wash, rotary evaporate, and vacuum dry to obtain modified hyperbranched epoxy resin. The preparation process of amino-terminated polyester microspheres is as follows: tripropylene glycol diacrylate, acetonitrile, and piperazine are mixed, sealed, and stirred for 30-40 minutes. After stirring evenly, the mixture is reacted at 2-4℃ for 12-14 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain amino-terminated polyester microspheres.

2. The method for preparing a high-strength ceramic proppant according to claim 1, characterized in that: When preheating the ceramsite, the temperature is 130-150℃ and the time is 1-2 hours; the curing parameters are: curing temperature is 120-130℃ and curing time is 7-8 hours; the mineral powder particle size is 400-450 mesh; the drying temperature is 200-300℃; the sintering temperature is 1200-1300℃; and the particle size of the proppant in the finished ceramsite is 30-50 mesh.

3. The method for preparing a high-strength ceramsite proppant according to claim 1, characterized in that: The mineral powder components are as follows (by weight): 70-80 parts bauxite, 4-5 parts manganese powder, 10-12 parts potassium feldspar, and 4-5 parts dolomite; the ceramsite proppant components are as follows (by weight): 85-95 parts ceramsite, 10-15 parts modified hyperbranched epoxy resin, 3-5 parts amino-terminated polyester microspheres, and 1-2 parts curing agent.

4. The method for preparing a high-strength ceramsite proppant according to claim 1, characterized in that: In step S1, the content of each component of the epoxidized hydrophobic monomer is as follows (by mass): 3.5-4.5 parts acryloyl chloride, 0.04-0.05 parts cuprous chloride, 3-4 parts n-hexane, 3.5-4.0 parts 2,2,2-trifluoroethanol, 0.04-0.05 parts 4-dimethylaminopyridine, 0.25-0.30 parts sodium tungstate, 0.13-0.15 parts methyltrioctylammonium chloride, 8.5-9.0 parts 8wt% hydrogen peroxide, and 3.0-3.2 parts 85wt% phosphoric acid.

5. The method for preparing a high-strength ceramsite proppant according to claim 1, characterized in that: In step S2, the molar ratio of sebacic acid to diethylene glycol is 1.0:(1.2-1.3).

6. The method for preparing a high-strength ceramsite proppant according to claim 1, characterized in that: In step S3, the reaction mass ratio of bisphenol A, hydroxyl-terminated polyester, trimethylolpropane triglycidyl ether, epoxidized hydrophobic monomer, and catalyst is 1:(2.0-2.5):3:(3.5-4.0):(0.04-0.05); the catalyst is tetrabutylammonium bromide.

7. The method for preparing a high-strength ceramsite proppant according to claim 1, characterized in that: The reaction molar ratio of tripropylene glycol diacrylate and piperazine is 1:(1.5-1.7); the amount of tripropylene glycol diacrylate and piperazine in the reaction system is 5-8 wt%.

8. A high-strength ceramic proppant, characterized in that, Prepared by the preparation method according to any one of claims 1-7.

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