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CN-122010590-A - Ultralow-density high-strength ceramsite propping agent and preparation method thereof

CN122010590ACN 122010590 ACN122010590 ACN 122010590ACN-122010590-A

Abstract

The invention provides an ultralow-density high-strength ceramsite proppant and a preparation method thereof, wherein the preparation raw materials comprise, by weight, 40-50 parts of fly ash floating beads, 8-12 parts of expanded perlite microbeads, 10-15 parts of medium-grade bauxite, 5-8 parts of primary fly ash, 3-5 parts of boron nitride coated mullite hollow microspheres, 2-4 parts of nano silicon dioxide, 3-5 parts of microcrystalline cellulose, 2-3 parts of potassium feldspar powder, 2-4 parts of borate-starch grafted modified carboxymethyl cellulose, 1-2 parts of chopped carbon fibers and 20-40 parts of absolute ethyl alcohol. The ceramic proppant provided by the invention can efficiently regulate and control the overall density, can form a high-strength crystalline phase, improves the binding force of particles and the hardness of microspheres, can inhibit crack growth, reduces sintering temperature, ensures stable structure, and has uniform powder dispersion and uniform product performance.

Inventors

  • MENG QINGKE
  • LIU SHIKAI
  • ZHENG XINHUA
  • ZHAO CHAOFENG
  • XU PENGYU
  • MA CHENGLIANG
  • ZHANG JIANZHONG
  • ZHAO WUJUN
  • PENG QIAN

Assignees

  • 郑州德赛尔陶粒有限公司

Dates

Publication Date
20260512
Application Date
20260202

Claims (9)

  1. 1. The ultra-low density high strength ceramsite proppant is characterized by comprising, by weight, 40-50 parts of fly ash floating beads, 8-12 parts of expanded perlite microbeads, 10-15 parts of medium-grade bauxite, 5-8 parts of primary fly ash, 3-5 parts of boron nitride coated mullite hollow microspheres, 2-4 parts of nano silicon dioxide, 3-5 parts of microcrystalline cellulose, 2-3 parts of potassium feldspar powder, 2-4 parts of borate-starch grafted modified carboxymethyl cellulose, 1-2 parts of chopped carbon fibers and 20-40 parts of absolute ethyl alcohol.
  2. 2. The ultra-low density high strength ceramic proppant according to claim 1, wherein the medium grade bauxite has an Al 2 O 3 -70%, a particle size of 200-300 mesh, a first grade fly ash loss on ignition of 5% or less, a SiO 2 content of 40% or more, a nano silica gas phase nano silica with a specific surface area of 180-220m 2 /g, a chopped carbon fiber length of 0.5-1mm and a diameter of 10-20 μm.
  3. 3. The ultra-low density high strength ceramic proppant according to claim 1, wherein the preparation raw materials of the boron nitride coated mullite hollow microsphere comprise, by weight, 20-25 parts of ethyl orthosilicate, 8-10 parts of aluminum nitrate, 75-90 parts of absolute ethyl alcohol, 25-30 parts of deionized water, 10-12 parts of liquid paraffin, 2-3 parts of sorbitan monooleate and 5-10 parts of ammonia water with a mass fraction of 5% -8%.
  4. 4. The ultra-low density high strength ceramic proppant of claim 3, wherein the method for preparing the boron nitride coated mullite hollow microspheres comprises the steps of: 1) Uniformly mixing absolute ethyl alcohol and deionized water according to a volume ratio of 3:1, adding tetraethoxysilane and aluminum nitrate, adjusting pH to 3.0-3.5 by adopting dilute nitric acid with mass fraction of 1-5%, and magnetically stirring for 20-30min at a rotating speed of 300-400r/min to obtain silica-alumina sol; 2) Mixing liquid paraffin with sorbitan monooleate as an oil phase, shearing at high speed of 8000-10000r/min, dripping the oil phase into silica-alumina sol, emulsifying for 15-20min at oil-water volume ratio of 1:5 to form W/O emulsion; 3) Dropwise adding ammonia water with the mass fraction of 5% -8% into the microspheres obtained in the step 2), regulating the pH to 8.0-8.5, standing and aging for 12-16h at 50-60 ℃, and centrifugally separating for 10-15min at the rotating speed of 8000-10000r/min to obtain core-shell microspheres; 4) Washing the core-shell microspheres with absolute ethyl alcohol for 3-5 times, then placing the core-shell microspheres in a blast drying oven at 60-80 ℃ for drying for 8-10 hours, transferring the core-shell microspheres into a muffle furnace, heating the core-shell microspheres to 1100-1200 ℃ at 5-8 ℃ per min in an air atmosphere, and preserving heat for 2-3 hours to obtain mullite hollow microspheres; 5) Placing the mullite hollow microspheres in a tube furnace, introducing nitrogen at a rate of 100-200mL/min as carrier gas, heating to 800-900 ℃, introducing a borane and ammonia mixed gas with a volume ratio of 1:2, performing chemical vapor deposition for 2-3h under normal pressure at a total flow rate of 150-300mL/min, and cooling to obtain the boron nitride coated mullite hollow microspheres.
  5. 5. The ultra-low density high strength ceramic proppant of claim 1, wherein the raw materials for preparing the borate-starch graft modified carboxymethyl cellulose comprise, by weight, 10-12 parts of carboxymethyl cellulose, 3-4 parts of soluble starch, 5-6 parts of trimethyl borate, 100-120 parts of deionized water, 30-40 parts of absolute ethyl alcohol and 0.1-0.3 part of ammonium persulfate.
  6. 6. The ultra-low density high strength ceramic proppant of claim 5, wherein the preparation method of the borate-starch graft modified carboxymethyl cellulose comprises the following steps: (1) Dissolving carboxymethyl cellulose in deionized water, and stirring at 200-300r/min for 30-40min under the water bath condition of 50-60 ℃ to obtain carboxymethyl cellulose aqueous solution; (2) Dissolving soluble starch and trimethyl borate in all absolute ethyl alcohol, and stirring for 15-25min at 200-300r/min to obtain monomer mixed solution; (3) Dropwise adding the monomer mixture into carboxymethyl cellulose water solution, stirring at 50-60 ℃ for 10-15min at 200-300r/min, introducing nitrogen to purge oxygen for 20-30min, adding ammonium persulfate, and stirring at 200-300r/min for reaction for 4-6h; (4) Slowly pouring the reaction liquid obtained in the step (3) into absolute ethyl alcohol for precipitation, filtering, placing a filter cake into a vacuum drying oven, drying for 10-12h under the conditions of vacuum degree of-0.08 MPa to-0.10 MPa and 60-70 ℃, and crushing to 200-300 meshes to obtain the borate-starch graft modified carboxymethyl cellulose.
  7. 7. A method of preparing the ultra-low density high strength ceramsite proppant of any one of claims 1-6, comprising the steps of: S1, respectively placing fly ash floating beads, expanded perlite microbeads, medium-grade bauxite, primary fly ash and potassium feldspar powder in a blast drying oven, and drying for 4-6 hours at 105-110 ℃ until the water content is less than or equal to 2%; S2, adding the pretreated material in the step S1, microcrystalline cellulose, chopped carbon fibers and nano silicon dioxide into a ball mill, adding absolute ethyl alcohol, controlling the ball-material ratio to be 3:1, and performing ball milling at the ball milling rotating speed of 200-250r/min for 1.5-2h to obtain uniform dry-mixed slurry; S3, adding boron nitride coated mullite hollow microspheres into the dry mixed slurry, and continuing ball milling for 30-40min; S4, preparing aqueous solution with mass fraction of 5% -8% of borate-starch graft modified carboxymethyl cellulose by deionized water, slowly dripping the aqueous solution into the slurry, stirring for 20-30min at 150-200r/min, granulating by a disc granulator at speed of 30-40r/min for 10-15min to obtain ceramsite green pellets with particle size of 0.8-2.0 mm; s5, placing the ceramsite green pellets into a blast drying oven, firstly drying for 2-3 hours at 40-50 ℃, and then heating to 80-90 ℃ and drying for 4-5 hours until the water content is less than or equal to 1%; s6, placing the dried green pellets in a muffle furnace, heating to 400-500 ℃ at 5-8 ℃ per min, preserving heat for 1-1.5h, heating to 1150-1250 ℃ at 3-5 ℃ per min, preserving heat for 2-3h, and cooling to room temperature at 2-3 ℃ per min to obtain a ceramsite semi-finished product; S7, preparing nano silicon dioxide into a suspension with the mass fraction of 3% -5% by using absolute ethyl alcohol, immersing the ceramsite semi-finished product into the suspension for 1-2min, taking out, and then placing the suspension in a 60-70 ℃ drying oven for drying for 2-3h to obtain the ultra-low density high strength ceramsite propping agent.
  8. 8. The method of producing ultra-low density and high strength ceramic proppant according to claim 7, wherein in step S4, the environmental humidity of the disc granulator is controlled to be 40% -60%.
  9. 9. The method of preparing ultra-low density and high strength ceramic proppant according to claim 7, wherein in step S7, the suspension is stirred at 300-400 r/min.

Description

Ultralow-density high-strength ceramsite propping agent and preparation method thereof Technical Field The invention relates to the technical field of ceramic propping agents, in particular to an ultralow-density high-strength ceramic propping agent and a preparation method thereof. Background The ceramic proppant is a core functional material for hydraulic fracturing exploitation of oil and gas fields, and the density and mechanical strength of the ceramic proppant directly influence the diversion capacity of artificial cracks and the long-term production efficiency of oil and gas wells. Along with the extension of oil gas exploitation to deep wells and unconventional reservoirs, the fracturing operation provides double performance requirements of ultralow density and high strength for the ceramic propping agent, and meanwhile, the direction has become an important development direction in the field of deep processing of nonmetallic minerals by relying on the low-carbon preparation concepts of industrial solid waste resource utilization and low-energy-consumption sintering. In the prior art, in order to realize the ultralow density of the ceramic proppant, the modes of introducing light hollow particles, adding pore-forming agents and the like are usually adopted, and aluminum-silicon raw materials are added to promote the generation of high-strength crystalline phases for improving the mechanical strength, but the synergistic regulation effect of the light hollow particles and the pore-forming agents is poor, the conventional means is adopted to reduce the density, so that the pore structure of the proppant matrix is uneven, the bonding strength among the particles is insufficient, the mechanical properties such as compressive strength are obviously reduced, and the use requirement of deep well high closing pressure cannot be met. Meanwhile, the traditional preparation process depends on high sintering temperature to ensure crystal phase development and bonding effect among raw materials, so that the production energy consumption is high, and the production process is contrary to the development requirement of industrial low-carbon preparation. Therefore, developing a ceramic proppant which can realize the synergistic optimization of ultra-low density and high strength performance and is suitable for low-carbon preparation requirements and a preparation method thereof becomes a technical problem to be solved in the field. Disclosure of Invention Aiming at the problems in the prior art, the invention provides an ultralow-density high-strength ceramsite proppant and a preparation method thereof. In order to achieve the above purpose, the invention is realized by the following technical scheme: The invention discloses an ultralow-density high-strength ceramsite proppant which is prepared from, by weight, 40-50 parts of fly ash floating beads, 8-12 parts of expanded perlite microbeads, 10-15 parts of medium-grade bauxite, 5-8 parts of primary fly ash, 3-5 parts of boron nitride coated mullite hollow microspheres, 2-4 parts of nano silicon dioxide, 3-5 parts of microcrystalline cellulose, 2-3 parts of potassium feldspar powder, 2-4 parts of borate-starch grafted modified carboxymethyl cellulose, 1-2 parts of chopped carbon fibers and 20-40 parts of absolute ethyl alcohol. According to the technical scheme, the fly ash floating beads and the expanded perlite microbeads can cooperatively reduce the overall density of the propping agent, the middle-grade bauxite provides an alumina component, the first-grade bauxite supplements a silica component, the two components can participate in forming a high-strength crystalline phase, the hollow mullite microsphere coated with boron nitride is reduced in an auxiliary manner by virtue of a hollow structure, the boron nitride coating layer can remarkably improve the hardness of the microsphere, nano silica can fill gaps among raw materials, the bonding strength among particles is enhanced by silica bonds formed after sintering, microcrystalline cellulose can form pores in the sintering process, the density of the propping agent is adjusted, potassium feldspar powder is used as a fluxing agent, the sintering temperature of a system can be reduced, the bonding and crystalline phase growth among the raw materials are promoted, the borate-starch grafting modified carboxymethyl cellulose can promote the bonding performance among the raw materials, the green ball forming and the structural stability after sintering are ensured, the chopped carbon fibers can be dispersed in a matrix, the crack expansion is restrained, the mechanical property of the propping agent is improved, and the components of each powder can be uniformly dispersed by anhydrous alcohol, and the uniformity of the propping agent is ensured. Preferably, the content of Al 2O3 in the medium-grade bauxite is 60-70%, the grain size is 200-300 meshes, the ignition loss of the primary fly ash is less than or equal to