High-performance well cementation cement system for deep geothermal development

Abstract

The invention discloses a high-performance well cementation cement system for deep geothermal development, and relates to the technical field of well cementation materials for oil and gas field development. The well cementation cement system is prepared from the following components in parts by weight: 100 parts of a cementing material, 35 to 40 parts of a high-temperature reinforcing material, 7 to 10 parts of a high-thermal-conductivity toughening composite material, 0.5 to 1.5 parts of a suspension stabilizer, 0.3 to 0.6 part of a dispersing agent, 1.5 to 2.5 parts of a fluid loss agent, 1.0 to 2.5 parts of a retarder and 0.1 part of a de-foaming agent, the solid-to-liquid ratio of the well cementation cement system is 0.40 to 0.50. The high-temperature stability, corrosion resistance and long-term durability of the set cement can be guaranteed, and the heat conductivity of the set cement can be greatly improved. The cement slurry has the characteristics of higher high-temperature strength, low high-temperature strength decline rate, lower elastic modulus, high heat transfer efficiency and the like, can realize excellent engineering performance of the well cementation cement slurry under the condition of a hot dry rock high-temperature environment, and meets the engineering construction requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of cementing materials for oil and gas field development, and more particularly to a high-performance cementing system for deep geothermal development. Background Art

[0002] Geothermal resources, as a heat source, offer advantages such as stability, high efficiency, low carbon footprint, environmental friendliness, and renewable energy. Hot dry rock geothermal power generation is a technological approach that effectively utilizes geothermal resources. Its basic principle involves injecting high-pressure water into rock formations 2,000 to 6,000 meters underground through injection wells. This water penetrates artificially fractured fissures and absorbs heat from the rock, generating high-temperature water and steam reaching temperatures of 150 to 200°C. This high-temperature water and steam, after heat exchange, are then extracted to the surface through production wells. This heat exchange is then used to circulate through a ground-based power generation device for steam generation. The cooled water is then reinjected underground for recycling, generating continuous electricity. This geothermal development model, known as the Enhanced Geothermal System (EGS), is currently the most prevalent.

[0003] Compared to cement used in oil and gas resource development, cementing materials for hot dry rock low-heat power generation differ in several key respects, primarily in the cement's toughness, corrosion resistance, high-temperature durability, and thermal conductivity. For example, the cement requires superior toughness to withstand changes in formation fractures, temperature, and stress. The long-term cyclic injection of recovered water, combined with the various ions in the water, also places high demands on the cement's corrosion resistance. Furthermore, as a long-term geothermal power generation project, the cement must possess excellent high-temperature durability and long-term stability. Furthermore, excellent thermal conductivity ensures that the deep rock mass can transfer heat to the fluid within the wellbore.

[0004] Prior art, such as the invention patent publication number CN114163172A, entitled "A High-Temperature-Resistant Cement Slurry System for Hot Dry Rock Cementing," provides a cement slurry system base comprising oil well cement, a strength stabilizer, and a mineral admixture. The cement slurry system is prepared from this cement slurry base, one or more of a fluid loss additive, a dispersant, and a retarder, and water. Another example, the invention patent publication number CN117659971A, entitled "A High-Temperature-Resistant Cement Slurry System for Hot Dry Rock Cementing," utilizes silicate cement combined with nano-liquid silicon, iron ore powder, sodium silicate, polyvinyl alcohol, and other materials, and then adds a glass fiber-based whisker agent and flaky talc modifier to create a high-temperature-resistant cement system. For example, patent publication number CN119661179A, entitled "A Cement Slurry System, Its Preparation Method, and Application," discloses a cement slurry system with excellent thermal conductivity obtained by uniformly mixing cement, graphite slag, fluid loss additive, activating material, reinforcing agent, floating beads, and water. Another example is patent publication number CN119320255A, entitled "A Cementing Slurry Resistant to Ultra-High Temperatures and Large Temperature Differences, Its Preparation Method, and Application," which uses cement, quartz sand, silica fume, a fluid loss additive, a retarder, granular silicon, and water to prepare a cementing slurry capable of withstanding ultra-high temperatures of 180-220°C and large temperature differences exceeding 80°C. At the same time, the thermal conductivity of the cement slurry currently used for cementing is only 0.19 to 0.65 W / (m·K) after solidification, which is much smaller than the thermal conductivity of rock (1.6 to 3.6 W / (m·K)), resulting in a lower heat production rate of geothermal wells. The addition of ordinary thermal conductive materials to cement slurry will cause poor slurry stability, strength decline, poor fluidity, and the thermal conductivity is still not high enough to meet the requirements of geothermal well cementing operations. For example, Zhang Hao et al. (Factors Affecting Thermal Conductivity of Geothermal Well Cementing Materials) added natural flake graphite, iron powder, and quartz to cement, achieving a thermal conductivity of 1.87 W / (m·K), but reducing the compressive strength of the cement. Guo Wen et al. (Research on the Formulation of a Cement Slurry System for Geothermal Well Cementing with "Water Preservation and Heat Extraction" Based on a Hybrid Weighted Method) studied geothermal well insulation cement, using natural flake graphite, silicon carbide, and aluminum oxide to improve the thermal conductivity of the cementing material. However, the higher the thermal conductivity, the more significantly the compressive strength of the cement decreased, making it unable to meet general strength requirements.

[0005] The above-mentioned technical means have achieved some results in the high-temperature resistance and thermal conductivity of cement stone for cementing. However, there are still deficiencies in the cementing operation requirements for the extreme environment of deep geothermal, especially in terms of the toughness, corrosion resistance, high-temperature durability, long-term stability and thermal conductivity of cement stone. Summary of the Invention

[0006] In order to overcome the defects and deficiencies in the above-mentioned prior art, the present invention provides a high-performance cement system for deep geothermal development. The present invention aims to improve the difficulties of existing hot dry rock cement slurry such as slurry instability and poor long-term service performance under high temperature conditions, and to avoid problems such as poor high-temperature suspension stability of the slurry, low high-temperature strength, excessively high elastic modulus of cement stone, and low thermal conductivity efficiency. The present invention can not only ensure the high-temperature stability, corrosion resistance and long-term durability of the cement stone, but also greatly improve the thermal conductivity of the cement stone. It has the characteristics of high high-temperature strength, low high-temperature strength decay rate, low elastic modulus and high heat transfer efficiency, and can achieve excellent engineering performance of cement slurry under high-temperature dry rock environment conditions, meeting the needs of engineering construction.

[0007] In order to solve the above problems in the prior art, the present invention is implemented through the following technical solutions.

[0008] The present invention provides a high-performance cementing system for deep geothermal development. The cementing system comprises, by weight, 100 parts of a gelling material, 35-40 parts of a high-temperature reinforcing material, 7-10 parts of a high-thermal-conductivity toughening composite material, 0.5-1.5 parts of a suspension stabilizer, 0.3-0.6 parts of a dispersant, 1.5-2.5 parts of a fluid loss additive, 1.0-2.5 parts of a retarder, and 0.1 part of a defoamer. The solid-to-liquid ratio of the cementing system is 0.4-0.5. The cementitious material is prepared by compounding Grade G high sulfate resistance oil well cement and low hydration heat cement in a weight ratio of (40-50):(50-60); The high-temperature reinforcing material is prepared by mixing quartz sand, dehydrated pyrophyllite, single crystal silicon byproduct, ultrafine metakaolin and dolomite in a weight ratio of (40-45): (25-30): (10-15): (10-15): (5-10); The high thermal conductivity toughened composite material is prepared by spraying a modified composite high thermal conductivity material dispersion on the surface of a modified fiber reinforced material, drying, and mixing, wherein the mass ratio of the modified composite high thermal conductivity material dispersion to the modified fiber reinforced material is (85-90):(10-15); The modified composite high thermal conductive material dispersion is prepared by mixing water, the modified composite high thermal conductive material, nanocellulose fibers, xanthan gum, and polycarboxylic acid in a mass ratio of (68-79):(20-30):(0.5-1.0):(0.2-0.3):(0.3-0.7); The modified composite high thermal conductive material is prepared by compounding modified thermal conductive material A, modified thermal conductive material B and thermal conductive material C in a mass ratio of (50-60):(20-30):(15-20) and adopting a vibration mixing method; The modified thermal conductive material A is obtained by weighing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of (40-50):(35-40):(10-15):(5-10), mixing them by ball milling to obtain powder A, and then coating the obtained powder A with nano-SiO2 by a sol-gel method; The modified thermal conductive material B is prepared by weighing carbon black powder and graphite powder in a mass ratio of (40-45):(55-60), mixing them by ball milling to obtain powder B, and then subjecting the powder B to low-temperature plasma treatment using O2 as a modifying gas to form a mixture of modified carbon black and modified graphite, thereby obtaining the modified thermal conductive material B; The thermal conductive material C is obtained by mixing nano-AlN and nano-GaN in a mass ratio of (60-65):(35-40) by ball milling; The modified fiber-reinforced material is obtained by mixing carbon fibers and SiC whiskers in a mass ratio of (55-60):(40-45) and performing surface modification on the mixture.

[0009] Further preferably, when the modified composite high thermal conductivity material dispersion is sprayed on the surface of the modified fiber reinforced material, the spraying pressure is controlled to 0.3 MPa, and the distance between the spray gun and the surface of the modified fiber reinforced material is maintained at 14 cm-16 cm; after the spraying is completed, the sprayed material is sent to an infrared medium-temperature drying equipment and blown and mixed at a gas flow rate of 10 m / s for 5 minutes. After sufficient mixing, the high thermal conductivity toughened composite material is obtained.

[0010] Further preferably, the modified composite high thermal conductive material dispersion is prepared by adding water to a container with a stirring device and stirring at a speed of 500±50r / min, then adding nanocellulose fiber, xanthan gum and polycarboxylic acid in sequence, continuing to stir for 30 minutes, adding the modified composite high thermal conductive material, increasing the stirring speed to 800±50r / min, and continuing to stir for 1 hour to obtain the modified composite high thermal conductive material dispersion.

[0011] Further preferably, the modified thermal conductive material A is prepared by weighing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of (40~50):(35~40):(10~15):(5~10), mixing them by ball milling, setting the ball milling speed to 300±50r / min, and milling time to 1h to obtain powder A, and then coating the obtained powder A with nano-SiO2 by a sol-gel method.

[0012] More preferably, the specific process of coating the powder A with nano-SiO2 by the sol-gel method is as follows: Take 5g of powder A, 50ml of deionized water, 150ml of anhydrous ethanol and 5ml of NH3·H2O; add them to a container with a reflux condenser and perform ultrasonic dispersion in a 75°C water bath. The ultrasonic power is set to 300W and the ultrasonic time is 30min. After the ultrasonic dispersion, add 4ml of TEOS. In a 75°C water bath environment, continue magnetic stirring at a speed of 500±50r / min for 2h to allow it to react uniformly. After the reaction is completed, filter by suction to obtain a solid powder; then wash the solid powder with anhydrous ethanol, isopropanol and deionized water in sequence to remove unreacted NH3·H2O and TEOS. Finally, the obtained solid powder is dried in an 85°C oven to obtain a multi-component composite metal oxide SiO2-coated nanomaterial, namely, modified thermal conductive material A.

[0013] More preferably, the particle size of nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in the raw materials of the modified thermal conductive material A is in the range of 50nm to 80nm.

[0014] More preferably, the solute mass fraction of the NH3·H2O is 25%.

[0015] Further preferably, the modified thermally conductive material B is prepared by weighing carbon black powder and graphite powder in a mass ratio of (40~45):(55~60), mixing them by ball milling, with a ball milling speed of 300±50r / min and a ball milling time of 1h to obtain powder B, and then using O2 as the modifying gas, the O2 gas flow rate is set to 80ml / min, and the powder B is subjected to low-temperature plasma treatment, wherein the low-temperature plasma treatment temperature is 65°C and the processing power is 150w, so that the powder B becomes a mixture of modified carbon black and modified graphite, thereby obtaining the modified thermally conductive material B.

[0016] Further preferably, among the raw materials of the modified thermal conductive material B, the carbon black powder has a particle size range of 10 μm to 20 μm, and a carbon content of more than 95%; the graphite powder has a natural flake structure, a particle size range of 10 μm to 50 μm, and a carbon content greater than 90%.

[0017] Further preferably, the particle sizes of the nano-AlN and nano-GaN in the thermal conductive material C are both in the range of 60 nm to 100 nm.

[0018] Further preferably, the surface modification treatment steps of the modified fiber reinforced material are as follows: 10 g of a mixed fiber reinforced material prepared by mixing carbon fiber and SiC whisker in a mass ratio of (55-60):(40-45) was placed in 100 ml of deionized water and ultrasonically dispersed for 30 min at an ultrasonic power of 300 W in a 50°C water bath. 50 ml of sodium dodecylbenzenesulfonate was added to the dispersion, and ultrasonic dispersion was continued for 15 min. Then, 25 ml of N-(hydroxymethyl)acrylamide was added, and the pH value of the solution was adjusted to 5. The mixture was magnetically stirred at a speed of 400±50 r / min for 3 h and then cooled to room temperature. Finally, the mixture was filtered by suction, washed twice with deionized water, and vacuum dried at a drying temperature of 85°C to obtain a modified fiber reinforced material.

[0019] After the surface modification of the fiber-reinforced material, it not only wraps and protects the composite fiber to prevent it from being corroded and damaged in the cement slurry, but also changes its surface hydrophilicity, so that it can better fit and bond with the modified composite high thermal conductivity material, so that the various materials can better play a synergistic role. While ensuring high thermal conductivity efficiency, it can also better play the role of fiber toughening and strengthening the strength of cement stone.

[0020] More preferably, the mass volume concentration of the sodium dodecylbenzenesulfonate is 0.05 g / ml.

[0021] More preferably, the mass volume concentration of the N-(hydroxymethyl)acrylamide is 0.05 g / ml.

[0022] Further preferably, the carbon fiber is a mesophase pitch-based carbon fiber with a tensile strength of ≥1200 MPa, an elastic modulus of ≥200 GPa, a thermal conductivity of ≥900 W / (m·K), a fiber length controlled within the range of 1 mm to 3 mm, and a fiber diameter range of 5 μm to 10 μm; the SiC whisker is β -SiC whiskers with diameters ranging from 0.1μm to 1μm and lengths ranging from 5μm to 30μm.

[0023] Further preferably, the average diameter of the nanocellulose fibers is 10 nm; the molecular weight of the xanthan gum is 4 million to 6 million; and the polycarboxylic acid is a polycarboxylic acid with maleic anhydride as the main chain and grafted with polyethers of different side chain lengths.

[0024] Further preferably, in the high-temperature reinforcing material, the SiO2 content in the quartz sand is above 96%, and the particle fineness thereof is above 200 mesh; the SiO2 content in the dehydrated pyrophyllite is above 60%, the Al2O3 content is above 15%, and the particle fineness thereof is above 300 mesh; the SiO2 content in the single crystal silicon by-product is above 98%; the powder particle size of the ultrafine kaolin is above 600 mesh; the CaO content in the dolomite is above 30%, the MgO content is above 10%, the SiO2 content is above 10%, and the particle size thereof is above 300 mesh.

[0025] Further preferably, the low hydration heat cement has a dicalcium silicate content of not less than 42%, a tricalcium aluminate content of not more than 6%, a free calcium oxide content of not more than 1%, and a hydration heat of not more than 300 kJ / kg at 28 days.

[0026] Further preferably, the suspension stabilizer comprises, by weight, 7% sodium tannate, 8% sodium lignin sulfonate, and 85% modified bentonite powder.

[0027] Further preferably, the dispersant is at least one of polystyrene sulfonate, polynaphthalene sulfonate, lignin sulfonate and ketone-aldehyde condensation polymers; the fluid loss additive is at least one of polyamide, polyvinyl alcohol and AMPS polymer; the retarder is at least one of tartrate, citric acid, boric acid and phosphate; and the defoamer is at least one of polypropylene alcohol, organosilicon and tributyl phosphate.

[0028] Compared with the prior art, the beneficial technical effects brought about by the present invention are as follows: 1. The theoretical density of the cement paste in the present invention is in the range of 1.80~1.95g / cm 3 The applicable ground temperature can reach 250℃, the compressive strength after 3 days of curing can be above 38MPa, and the 28d strength decline rate is less than 5%. The maximum density difference between the upper and lower cement stones is only 0.02g / cm 3 , the thickening time can be adjusted according to actual needs.

[0029] 2. The cementitious material of the present invention is compounded with G-grade oil well cement and low-hydration hot cement. The low-hydration hot cement has a lower calcium-silicon ratio than ordinary cement, and its long-term strength stability is higher, which can reduce the strength decay rate at high temperatures. However, its early strength develops relatively slowly. Therefore, after compounding with G-grade oil well cement, the phenomenon of slow early strength development and significant late strength decay when using low-hydration hot cement alone can be avoided to a certain extent, and the long-term service requirements of deep geothermal hot dry rock cementing cement can be met.

[0030] 3. The high-temperature enhancement material of the present invention contains dehydrated pyrophyllite and polysilicon by-products, which contain a large amount of active SiO2 components, which can provide the siliceous material components required for high-temperature cementing to a certain extent; the ultrafine kaolin not only provides some siliceous and aluminum materials to the slurry system, but also has a beneficial effect on the suspension stability of the slurry, avoiding the problem of slurry instability and stratification at high temperatures.

[0031] 4. The high thermal conductivity material of the present invention is compounded from modified nano-metal oxides, modified carbon materials, and oxide ceramic materials. A composite structure is formed by metal oxides such as nano-CuO and TiO2 and a nano-SiO2 coating layer. The nano-metal oxide itself has high thermal conductivity. The nano-scale particles give it nano-scale characteristics in the cement paste, which can generate a weak potential difference to disperse the particulate material in the paste and construct a continuous thermal conductivity path. Secondly, after the nano-SiO2 is used to wrap the nano-metal oxide material, the surface hydrophilicity of the nano-metal oxide is improved, which not only enhances the dispersibility of the material and prevents agglomeration that reduces thermal conductivity, but also enhances the bonding between the nano-material and the cement paste, making it easier to disperse in the cement paste, so that the paste can form a three-dimensional network structure. The various binders in the paste can be more easily suspended, greatly enhancing the colloidal stability of the paste, and are more likely to participate in the cement hydration process reaction and be embedded in it, greatly improving the thermal conductivity of the cement paste. It can also fill the micropores and cracks of the hardened cement paste, thereby greatly reducing the permeability of the cement paste. Secondly, after low-temperature plasma treatment, polar groups are introduced on the surface of carbon black and graphite, which improves the interfacial bonding with the cement matrix while maintaining the high thermal conductivity of the carbon material to form a carbon-based thermal conductive network; at the same time, nano-AlN and GaN, as nitride ceramic materials, have both ultra-high thermal conductivity and high-temperature resistance, which compensates for the performance attenuation of metal oxides and carbon materials at high temperatures and ensures the stability of thermal conduction in dry hot rock environments.

[0032] 5. The modified fiber reinforcement material in the present invention is a mixture of mesophase asphalt-based carbon fibers and β-SiC whiskers, which can form a composite reinforcement mechanism of "coarse fibers bearing stress + fine whiskers bridging cracks". The carbon fibers bear the main load, and the SiC whiskers fill microcracks and inhibit crack propagation, which can greatly improve the compressive strength and flexural strength of the cement stone. By functionalizing the fiber surface, polar groups such as hydroxyl and amide groups are introduced to form chemical bonds with cement hydration products (such as CSH gel), thereby reducing pore defects at the interface between the fiber and the matrix, improving interfacial bonding strength, and avoiding the degradation of mechanical properties caused by traditional thermal conductive fillers (such as pure carbon black).

[0033] 6. The high thermal conductivity toughening composite material in the present invention is a composite material made by surface spraying, bonding, drying and dispersing a composite modified high thermal conductivity material and a modified fiber reinforcement material. On the premise of improving the thermal conductivity of cement stone, it can also improve the toughness of cement stone, so that the cement ring is not prone to cracks in subsequent operations. Among them, the multi-material compounding of metal oxides, carbon materials, nitride ceramic materials and thermally conductive toughening fiber materials has a multi-material composite synergistic effect, which can form a "point-line-surface" multi-dimensional thermal conductive network structure, which can not only fill the tiny gaps and cracks in cement stone, but also participate in the cement hydration process, making the solidified cement stone more compact and with lower permeability, and further reducing the elastic modulus of cement stone. In addition, the thermal conductivity of cement stone can be increased by several times compared with traditional cement stone, which significantly improves the heat transfer efficiency of cement stone. DETAILED DESCRIPTION

[0034] The technical solutions of the present invention are further described in detail below in conjunction with the examples. It should be noted that the embodiments described below are only preferred embodiments of the present invention and not all embodiments. Therefore, these embodiments are only used to help understand the present invention and do not constitute a limitation of the present invention.

[0035] The cementitious material described in the following embodiments of the present invention is prepared by compounding Grade G high sulfate resistance oil well cement and low heat of hydration cement in a certain weight ratio; wherein the low heat of hydration cement has a dicalcium silicate content of not less than 42%, a tricalcium aluminate content of not more than 6%, a free calcium oxide content of not more than 1%, and a hydration heat of not more than 300 kJ / kg at 28 days.

[0036] The high-temperature reinforcing material described in the following embodiments of the present invention is a compound of quartz sand, dehydrated pyrophyllite, polycrystalline silicon by-product, ultrafine kaolin and dolomite in a certain weight ratio; wherein the SiO2 content in the quartz sand is above 96%, and its particle fineness is above 200 mesh; the SiO2 content in the dehydrated pyrophyllite is above 60%, the Al2O3 content is above 15%, and its particle fineness is above 300 mesh; the SiO2 content in the single crystal silicon by-product is above 98%; the powder particle size of the ultrafine kaolin is above 600 mesh; the CaO content in the dolomite is above 30%, the MgO content is above 10%, the SiO2 content is above 10%, and its particle size is above 300 mesh.

[0037] The high thermal conductivity toughened composite materials described in the following embodiments of the present invention are prepared by spraying a modified composite high thermal conductivity material dispersion on the surface of a modified fiber reinforcement material, drying, and mixing. The specific preparation method is as follows: After weighing water, modified composite high thermal conductive material, nanocellulose fiber, xanthan gum and polycarboxylic acid according to the set mass ratio, first add water into a container with a stirring device and stir at a speed of 500±50r / min. Then add nanocellulose fiber, xanthan gum and polycarboxylic acid in sequence and continue stirring for 30 minutes. Finally, add the modified composite high thermal conductive material and increase the stirring speed to 800±50r / min. Stir for another 1 hour to obtain a modified composite high thermal conductive material dispersion.

[0038] The modified composite high thermal conductivity material dispersion is evenly sprayed on the surface of the modified fiber reinforced material. The spraying pressure is controlled to 0.3 MPa during spraying, and the distance between the spray gun and the material surface is maintained at about 15 cm (generally within the range of 14 cm-16 cm). After spraying, the material is sent to the infrared medium-temperature drying equipment, the drying temperature is set to 85 ° C, and the drying time is 1 hour. The dried material is then blown and mixed through a high-speed gas blowing and mixing equipment at a gas flow rate of 10 m / s. The blowing and mixing time is 10 minutes to fully mix the modified composite high thermal conductivity material and the modified fiber reinforced material to finally obtain a high thermal conductivity toughened composite material.

[0039] As an example of the following embodiments, the average diameter of the nanocellulose fibers is 10 nm; the molecular weight of the xanthan gum is 4 to 6 million; and the polycarboxylic acid is a polycarboxylic acid with maleic anhydride as the main chain and polyethers of different side chain lengths grafted thereon.

[0040] The modified composite high thermal conductive material mentioned above and the modified composite high thermal conductive material in the following embodiments are obtained by compounding modified thermal conductive material A, modified thermal conductive material B and thermal conductive material C in a set mass ratio by vibration mixing.

[0041] The modified thermal conductive material A is prepared by mixing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a set mass ratio, using a ball milling method, with the ball milling speed set to 300±50r / min and the ball milling time being 1h to obtain powder A, and then the obtained powder A is coated with nano-SiO2 using a sol-gel method.

[0042] The modified thermal conductive material B is prepared by mixing carbon black powder and graphite powder in a set mass ratio, using ball milling for mixing, with a ball milling speed of 300±50r / min and a ball milling time of 1h to obtain powder B, and then using O2 as a modifying gas to perform low-temperature plasma treatment on powder B, wherein the O2 gas flow rate is set to 80ml / min, the low-temperature plasma treatment temperature is 65°C, and the treatment power is 150w, so that powder B becomes a mixture of modified carbon black and modified graphite, thereby obtaining the modified thermal conductive material B.

[0043] The thermal conductive material C is obtained by mixing nano-AlN and nano-GaN in a certain mass ratio and then ball milling, wherein the ball milling speed is 300±50 r / min and the ball milling time is 1 hour.

[0044] As examples of the following embodiments of the present invention, the raw materials for modified thermal conductive material A include nano-CuO, nano-TiO2, nano-Sc2O3, and nano-Y2O3, with particle sizes ranging from 50 to 80 nm. The raw materials for modified thermal conductive material B include carbon black powder with a particle size range of 10 to 20 μm and a carbon content exceeding 95%. The graphite powder has a natural flake structure, a particle size range of 10 to 50 μm, and a carbon content exceeding 90%. The nano-AlN and nano-GaN particles in thermal conductive material C range in size from 60 to 100 nm.

[0045] The process of coating powder A with nano-SiO2 by sol-gel method in the above and following examples is as follows: Take 5g of powder A, 50ml of deionized water, 150ml of anhydrous ethanol and 5ml of NH3·H2O (25% concentration); add them into a container with a reflux condenser and perform ultrasonic dispersion in a 75℃ water bath with the ultrasonic power set to 300W and the ultrasonic time set to 30min. After the ultrasonic dispersion, add 4ml of TEOS and continue magnetic stirring at a speed of 500±50r / min for 2h in a 75℃ water bath environment to ensure uniform reaction. After the reaction, filter by suction to obtain a solid powder; then wash the solid powder with anhydrous ethanol, isopropanol and deionized water in sequence to remove unreacted NH3·H2O and TEOS. Finally, dry the obtained solid powder in an 85℃ oven to obtain a multi-component composite metal oxide SiO2-coated nanomaterial, namely, modified thermal conductive material A.

[0046] The modified fiber-reinforced materials described in the above and following embodiments of the present invention are obtained by mixing carbon fibers and SiC whiskers in a certain mass ratio and modifying their surfaces.

[0047] The surface modification treatment steps of the fiber-reinforced material described in the above and following embodiments of the present invention are as follows: 10 g of a mixed fiber-reinforced material prepared by mixing carbon fibers and SiC whiskers in a set mass ratio is placed in 100 ml of deionized water, ultrasonically dispersed in a 50° C. water bath at an ultrasonic power of 300 W for 30 min, and then 50 ml of sodium dodecylbenzenesulfonate (0.05 g / ml mass volume concentration) is added to the dispersion. After ultrasonic dispersion is continued for 15 min, 25 ml of N-(hydroxymethyl)acrylamide (0.05 g / ml mass volume concentration) is added, the pH value of the solution is adjusted to 5, and the reaction is carried out by magnetic stirring at a speed of 400±50 r / min for 3 h, and then cooled to room temperature. Finally, the mixture is filtered by suction, washed twice with deionized water, and vacuum dried at a drying temperature of 85° C. to obtain a modified fiber-reinforced material.

[0048] As an example of the following embodiment of the present invention, the carbon fiber is a mesophase pitch-based carbon fiber with a tensile strength of ≥1200 MPa, an elastic modulus of ≥200 GPa, a thermal conductivity of ≥900 W / (m·K), a fiber length of 1 to 3 mm, and a fiber diameter of 5 to 10 μm; the SiC whisker is β Type SiC whiskers, with diameters ranging from 0.1 to 1 μm and lengths ranging from 5 to 30 μm.

[0049] The suspension stabilizer used in the embodiments of the present invention is preferably the slurry stabilizer disclosed in Patent No. ZL202110550154.8, with a specific weight ratio of 7% sodium tannate, 8% sodium lignin sulfonate, and 85% modified bentonite powder. As an alternative, other ratios within the scope of Patent No. ZL202110550154.8 may also be used.

[0050] In the embodiment of the present invention, the dispersant is at least one of polystyrene sulfonate, polynaphthalene sulfonate, lignin sulfonate and ketone-aldehyde condensation polymer; the loss reducing agent is at least one of polyamide, polyvinyl alcohol and AMPS polymer; the retarder is at least one of tartrate, citric acid, boric acid and phosphate; and the defoamer is at least one of polypropylene alcohol, silicone and tributyl phosphate.

[0051] Example 1 As a preferred embodiment of the present invention, this embodiment discloses a high-performance cement system for deep geothermal development, comprising the following components, calculated by weight: 100 parts of a cementitious material, 36 parts of a high-temperature reinforcing material, 7 parts of a high-thermal-conductivity toughening composite material, 0.8 parts of a suspension stabilizer, 0.3 parts of a dispersant, 2.0 parts of a fluid loss additive, 1.8 parts of a retarder, and 0.1 parts of a defoamer. The cement slurry system has a liquid-to-solid ratio of 0.44 and a theoretical slurry density of 1.87 g / cm3 .

[0052] The cementitious material is prepared by compounding G-grade high sulfate resistance oil well cement and low hydration heat cement in a weight ratio of 40:60.

[0053] The high-temperature reinforcing material is prepared by mixing quartz sand, dehydrated pyrophyllite, single crystal silicon by-product, ultrafine metakaolin and dolomite in a weight ratio of 45:25:15:10:5.

[0054] The high thermal conductivity toughened composite material is prepared by spraying a modified composite high thermal conductivity material dispersion on the surface of a modified fiber reinforcement material, drying, and mixing the modified composite material; wherein the mass ratio of the modified composite high thermal conductivity material dispersion to the modified fiber reinforcement material is 85:15; Specifically, the modified composite high thermal conductive material dispersion is prepared by weighing water, the modified composite high thermal conductive material, nanocellulose fibers, xanthan gum, and polycarboxylic acid in a mass ratio of 68:30:1:0.3:0.7, placing the mixture in a container and performing ultrasonic dispersion until the mixture is uniformly dispersed. The modified composite high thermal conductive material is compounded by modified thermal conductive material A, modified thermal conductive material B and thermal conductive material C in a mass ratio of 50:30:20; the modified thermal conductive material A is obtained by mixing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of 40:35:15:10 to obtain powder A, and the obtained powder A is coated with nano-SiO2 by a sol-gel method; the modified thermal conductive material B is obtained by mixing carbon black powder and graphite powder in a mass ratio of 45:55 to obtain powder B, and then subjecting powder B to low-temperature plasma treatment; the thermal conductive material C is obtained by mixing nano-AlN and nano-GaN in a mass ratio of 60:40; The modified fiber-reinforced material is obtained by mixing carbon fibers and SiC whiskers in a mass ratio of 58:42 and then performing surface modification on the mixture.

[0055] The suspension stabilizer is obtained by uniformly mixing 7% of sodium tannate, 8% of sodium lignin sulfonate and 85% of modified bentonite powder.

[0056] The dispersant is polycarboxylic acid.

[0057] The loss reducing agent is an AMPS polymer.

[0058] The retarder is tartrate.

[0059] The defoaming agent is polypropylene alcohol.

[0060] Example 2 As a preferred embodiment of the present invention, this embodiment discloses a high-performance cement system for deep hot dry rock development, comprising the following components by weight: 100 parts of a cementitious material, 37 parts of a high-temperature reinforcing material, 8 parts of a high-thermal-conductivity toughening composite material, 1.3 parts of a suspension stabilizer, 0.4 parts of a dispersant, 2.3 parts of a fluid loss additive, 2.2 parts of a retarder, and 0.1 parts of a defoamer. The cement slurry system has a liquid-to-solid ratio of 0.48 and a theoretical slurry density of 1.82 g / cm 3 .

[0061] The cementitious material is prepared by compounding Grade G high sulfate resistance oil well cement and low hydration heat cement in a weight ratio of 42:58.

[0062] The high-temperature reinforcing material is prepared by mixing quartz sand, dehydrated pyrophyllite, single crystal silicon by-product, ultrafine metakaolin and dolomite in a weight ratio of 40:28:14:11:7.

[0063] The high thermal conductivity toughened composite material is prepared by spraying a modified composite high thermal conductivity material dispersion on the surface of a modified fiber reinforcement material, drying, and mixing; wherein the mass ratio of the modified composite high thermal conductivity material dispersion to the modified fiber reinforcement material is 85:15; Specifically, the modified composite high thermal conductive material dispersion is prepared by weighing water, the modified composite high thermal conductive material, nanocellulose fibers, xanthan gum, and polycarboxylic acid in a mass ratio of 70:28.5:0.8:0.2:0.5, placing the mixture in a container and performing ultrasonic dispersion until the mixture is uniformly dispersed. The modified composite high thermal conductive material is compounded by modified thermal conductive material A, modified thermal conductive material B and thermal conductive material C in a mass ratio of 52:30:18; the modified thermal conductive material A is obtained by mixing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of 45:40:10:5 to obtain powder A, and the obtained powder A is coated with nano-SiO2 by a sol-gel method; the modified thermal conductive material B is obtained by mixing carbon black powder and graphite powder in a mass ratio of 43:57 to obtain powder B, and then low-temperature plasma treatment of powder B is performed; the thermal conductive material C is obtained by mixing nano-AlN and nano-GaN in a mass ratio of 63:37; The modified fiber-reinforced material is obtained by mixing carbon fibers and SiC whiskers in a mass ratio of 55:45 and then performing surface modification on the mixture.

[0064] The suspension stabilizer is obtained by uniformly mixing 7% of sodium tannate, 8% of sodium lignin sulfonate and 85% of modified bentonite powder.

[0065] The dispersant is a ketone-aldehyde condensation polymer.

[0066] The loss reducing agent is polyvinyl alcohol.

[0067] The retarder is citrate.

[0068] The defoaming agent is polypropylene alcohol.

[0069] Example 3 As a preferred embodiment of the present invention, this embodiment discloses a high-performance cement system for deep hot dry rock development, comprising the following components by weight: 100 parts of a cementitious material, 40 parts of a high-temperature reinforcing material, 10 parts of a high-thermal-conductivity toughening composite material, 1.5 parts of a suspension stabilizer, 0.3 parts of a dispersant, 2.5 parts of a fluid loss additive, 1.0 parts of a retarder, and 0.1 parts of a defoamer. The cement slurry system has a liquid-to-solid ratio of 0.50 and a theoretical slurry density of 1.80 g / cm 3 .

[0070] The cementitious material is prepared by compounding G-grade high sulfate resistance oil well cement and low hydration heat cement in a weight ratio of 50:50.

[0071] The high-temperature reinforcing material is prepared by mixing quartz sand, dehydrated pyrophyllite, single crystal silicon by-product, ultrafine metakaolin and dolomite in a weight ratio of 42:26:12:12:8.

[0072] The high thermal conductivity toughened composite material is prepared by spraying a modified composite high thermal conductivity material dispersion on the surface of a modified fiber reinforcement material, drying, and mixing; wherein the mass ratio of the modified composite high thermal conductivity material dispersion to the modified fiber reinforcement material is 88:12; Specifically, the modified composite high thermal conductive material dispersion is prepared by weighing water, the modified composite high thermal conductive material, nanocellulose fibers, xanthan gum, and polycarboxylic acid in a mass ratio of 75:23.5:0.7:0.3:0.5, placing the mixture in a container and performing ultrasonic dispersion until the mixture is uniformly dispersed. The modified composite high thermal conductive material is compounded by modified thermal conductive material A, modified thermal conductive material B and thermal conductive material C in a mass ratio of 55:28:17; the modified thermal conductive material A is obtained by mixing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of 50:35:10:5 to obtain powder A, and the obtained powder A is coated with nano-SiO2 by a sol-gel method; the modified thermal conductive material B is obtained by mixing carbon black powder and graphite powder in a mass ratio of 40:60 to obtain powder B, and then subjecting powder B to low-temperature plasma treatment; the thermal conductive material C is obtained by mixing nano-AlN and nano-GaN in a mass ratio of 65:35; The modified fiber reinforced material is obtained by mixing carbon fibers and SiC whiskers in a mass ratio of 60:40 and then performing surface modification on the mixture.

[0073] The suspension stabilizer is obtained by uniformly mixing 7% of sodium tannate, 8% of sodium lignin sulfonate and 85% of modified bentonite powder.

[0074] The dispersant is polystyrene sulfonate.

[0075] The fluid loss additive is a polyamide fluid loss additive.

[0076] The retarder is a phosphate retarder.

[0077] The defoaming agent is tributyl phosphate.

[0078] Example 4 As a preferred embodiment of the present invention, this embodiment discloses a high-performance cement system for deep hot dry rock development, comprising the following components by weight: 100 parts of a cementitious material, 39 parts of a high-temperature reinforcing material, 8 parts of a high-thermal-conductivity toughening composite material, 1.0 parts of a suspension stabilizer, 0.5 parts of a dispersant, 1.8 parts of a fluid loss additive, 2.0 parts of a retarder, and 0.1 parts of a defoamer. The cement slurry system has a liquid-to-solid ratio of 0.42 and a theoretical slurry density of 1.90 g / cm 3 .

[0079] The cementitious material is prepared by compounding G-grade high sulfate resistance oil well cement and low hydration heat cement in a weight ratio of 45:55.

[0080] The high-temperature reinforcing material is prepared by mixing quartz sand, dehydrated pyrophyllite, single crystal silicon by-product, ultrafine metakaolin and dolomite in a weight ratio of 43:30:11:10:6.

[0081] The high thermal conductivity toughened composite material is prepared by spraying a modified composite high thermal conductivity material dispersion on the surface of a modified fiber reinforcement material, drying, and mixing; wherein the mass ratio of the modified composite high thermal conductivity material dispersion to the modified fiber reinforcement material is 89:11; Specifically, the modified composite high thermal conductive material dispersion is prepared by weighing water, the modified composite high thermal conductive material, nanocellulose fibers, xanthan gum, and polycarboxylic acid in a mass ratio of 77:21.4:0.8:0.2:0.6, placing the mixture in a container and performing ultrasonic dispersion until the mixture is uniformly dispersed. The modified composite high thermal conductive material is compounded by modified thermal conductive material A, modified thermal conductive material B and thermal conductive material C in a mass ratio of 60:20:20; the modified thermal conductive material A is obtained by mixing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of 42:38:12:8 to obtain powder A, and the obtained powder A is coated with nano-SiO2 by a sol-gel method; the modified thermal conductive material B is obtained by mixing carbon black powder and graphite powder in a mass ratio of 42:58 to obtain powder B, and then subjecting powder B to low-temperature plasma treatment; the thermal conductive material C is obtained by mixing nano-AlN and nano-GaN in a mass ratio of 62:38; The modified fiber-reinforced material is obtained by mixing carbon fibers and SiC whiskers in a mass ratio of 57:43 and then performing surface modification on the mixture.

[0082] The suspension stabilizer is obtained by uniformly mixing 7% of sodium tannate, 8% of sodium lignin sulfonate and 85% of modified bentonite powder.

[0083] The dispersant is a ketone-aldehyde condensation polymer.

[0084] The loss reducing agent is polyvinyl alcohol.

[0085] The retarder is citrate.

[0086] The defoaming agent is tributyl phosphate.

[0087] Example 5 As a preferred embodiment of the present invention, this embodiment discloses a high-performance cement system for deep hot dry rock development, comprising the following components by weight: 100 parts of a cementitious material, 35 parts of a high-temperature reinforcing material, 9 parts of a high-thermal-conductivity toughening composite material, 0.5 parts of a suspension stabilizer, 0.6 parts of a dispersant, 1.5 parts of a fluid loss additive, 2.5 parts of a retarder, and 0.1 parts of a defoamer. The cement slurry system has a liquid-to-solid ratio of 0.40 and a theoretical slurry density of 1.95 g / cm 3 .

[0088] The cementitious material is prepared by compounding Grade G high sulfate resistance oil well cement and low hydration heat cement in a weight ratio of 47:53.

[0089] The high-temperature reinforcing material is prepared by mixing quartz sand, dehydrated pyrophyllite, single crystal silicon by-product, ultrafine metakaolin and dolomite in a weight ratio of 40:25:10:15:10.

[0090] The high thermal conductivity toughened composite material is prepared by spraying a modified composite high thermal conductivity material dispersion on the surface of a modified fiber reinforcement material, drying, and mixing; wherein the mass ratio of the modified composite high thermal conductivity material dispersion to the modified fiber reinforcement material is 90:10; Specifically, the modified composite high thermal conductive material dispersion is prepared by weighing water, the modified composite high thermal conductive material, nanocellulose fibers, xanthan gum, and polycarboxylic acid in a mass ratio of 79:20:0.5:0.2:0.3, placing the mixture in a container and performing ultrasonic dispersion until the mixture is uniformly dispersed. The modified composite high thermal conductive material is compounded by modified thermal conductive material A, modified thermal conductive material B and thermal conductive material C in a mass ratio of 58:27:15; the modified thermal conductive material A is obtained by mixing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of 48:36:10:6 to obtain powder A, and the obtained powder A is coated with nano-SiO2 by a sol-gel method; the modified thermal conductive material B is obtained by mixing carbon black powder and graphite powder in a mass ratio of 44:56 to obtain powder B, and then subjecting powder B to low-temperature plasma treatment; the thermal conductive material C is obtained by mixing nano-AlN and nano-GaN in a mass ratio of 64:36; The modified fiber-reinforced material is obtained by mixing carbon fibers and SiC whiskers in a mass ratio of 56:44 and then performing surface modification on the mixture.

[0091] The suspension stabilizer is obtained by uniformly mixing 7% of sodium tannate, 8% of sodium lignin sulfonate and 85% of modified bentonite powder.

[0092] The dispersant is polycarboxylic acid.

[0093] The loss reducing agent is an AMPS polymer.

[0094] The retarder is citric acid.

[0095] The defoaming agent is silicone.

[0096] Comparative Example 1 The comparative example is a conventional high-temperature cementing cement, which is composed of the following components in parts by weight: 100 parts of G-grade high-resistance oil well cement, 36 parts of quartz sand, 0.3 parts of dispersant, 2.0 parts of water-reducing agent, 1.8 parts of retarder, and 0.1 parts of defoamer. The liquid-to-solid ratio of the system is 0.44, and the theoretical density of the slurry is 1.86 g / cm 3 ; The types of dispersants, fluid loss additives, retarder and defoaming agents in this comparative example are the same as those in Example 1 above.

[0097] Comparative Example 2 The comparative solution is a conventional high-temperature cementing cement, which is composed of the following components in parts by weight: 100 parts of G-grade high-resistance oil well cement, 37 parts of quartz sand, 0.4 parts of dispersant, 2.3 parts of water-reducing agent, 2.2 parts of retarder, and 0.1 parts of defoamer. The liquid-to-solid ratio of the system is 0.48, and the theoretical density of the slurry is 1.82 g / cm 3 ; The types of dispersants, fluid loss additives, retarder and defoaming agents in this comparative example are the same as those in Example 2 above.

[0098] Comparative Example 3 The comparative example is a conventional high-temperature cementing cement, which is composed of the following components in parts by weight: 100 parts of G-grade high-resistance oil well cement, 40 parts of quartz sand, 0.3 parts of dispersant, 2.5 parts of water-reducing agent, 1.0 parts of retarder, and 0.1 parts of defoamer. The liquid-to-solid ratio of the system is 0.50, and the theoretical density of the slurry is 1.81 g / cm 3 ; The types of dispersants, fluid loss additives, retarder and defoaming agents in this comparative example are the same as those in Example 3 above.

[0099] Comparative Example 4 The comparative example is a conventional high-temperature cementing cement, which is composed of the following components in parts by weight: 100 parts of G-grade high-resistance oil well cement, 39 parts of quartz sand, 0.5 parts of dispersant, 1.8 parts of water-reducing agent, 2.0 parts of retarder, and 0.1 parts of defoamer. The liquid-to-solid ratio of the system is 0.42, and the theoretical density of the slurry is 1.90 g / cm 3 ; The types of dispersants, fluid loss additives, retarder and defoaming agents in this comparative example are the same as those in Example 4 above.

[0100] Comparative Example 5 The comparative example is a conventional high-temperature cementing cement, which is composed of the following components in parts by weight: 100 parts of G-grade high-resistance oil well cement, 35 parts of quartz sand, 0.6 parts of dispersant, 1.5 parts of water-reducing agent, 2.5 parts of retarder, and 0.1 parts of defoamer. The liquid-to-solid ratio of the system is 0.40, and the theoretical density of the slurry is 1.95 g / cm 3 ; The types of dispersants, fluid loss additives, retarder and defoamer in this comparative example are the same as those in Example 5 above.

[0101] Example 6 In this example, the cement slurries prepared in Examples 1-5 and Comparative Examples 1-5 were tested and analyzed according to GB / T 19139, "Test Methods for Oil Well Cement." The experimental conditions were as follows: a thickening temperature of 220°C, a thickening pressure of 100 MPa, a heating time of 150 minutes, a curing temperature of 250°C, and curing times of 1 day, 7 days, and 14 days, respectively. The experimental results are shown in the following table: From the experimental results in the table above, it can be seen that the density of the cement system in the present invention can be between 1.80 and 1.95 g / cm 3 The slurry thickening time can be adjusted according to actual needs. Compared with the experimental results in all comparative examples, the cement stones in all embodiments of the present invention do not show any strength decline after a certain curing age, and the permeability of the cement stones is much lower than the experimental data in the comparative examples. At the same time, the elastic modulus of the cement stones is low, and the toughness of the cement stones is good. In particular, the thermal conductivity of the cement stones is significantly improved, indicating that the cement system of the present invention has good engineering performance and meets the engineering requirements of deep geothermal hot dry rock power generation cementing operations.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention in any form. Any simple modification made by any technician familiar with the field without departing from the concept and principle of the technical solution of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A high-performance cementing system for deep geothermal development, characterized by: The cementing system comprises, by weight, 100 parts of a gelling material, 35-40 parts of a high-temperature reinforcing material, 7-10 parts of a high-thermal-conductivity toughening composite material, 0.5-1.5 parts of a suspension stabilizer, 0.3-0.6 parts of a dispersant, 1.5-2.5 parts of a fluid loss additive, 1.0-2.5 parts of a retarder, and 0.1 parts of a defoamer; the solid-to-liquid ratio of the cementing system is 0.4-0.5; The cementitious material is prepared by compounding Grade G high sulfate resistance oil well cement and low hydration heat cement in a weight ratio of (40-50):(50-60); The high-temperature reinforcing material is prepared by mixing quartz sand, dehydrated pyrophyllite, single crystal silicon byproduct, ultrafine metakaolin and dolomite in a weight ratio of (40-45): (25-30): (10-15): (10-15): (5-10); The high thermal conductivity toughened composite material is prepared by spraying a modified composite high thermal conductivity material dispersion on the surface of a modified fiber reinforced material, drying, and mixing, wherein the mass ratio of the modified composite high thermal conductivity material dispersion to the modified fiber reinforced material is (85-90):(10-15); The modified composite high thermal conductive material dispersion is prepared by mixing water, the modified composite high thermal conductive material, nanocellulose fibers, xanthan gum, and polycarboxylic acid in a mass ratio of (68-79):(20-30):(0.5-1.0):(0.2-0.3):(0.3-0.7); The modified composite high thermal conductive material is prepared by compounding modified thermal conductive material A, modified thermal conductive material B and thermal conductive material C in a mass ratio of (50-60):(20-30):(15-20) and adopting a vibration mixing method; The modified thermal conductive material A is obtained by weighing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of (40-50):(35-40):(10-15):(5-10), mixing them by ball milling to obtain powder A, and then coating the obtained powder A with nano-SiO2 by a sol-gel method; The modified thermal conductive material B is prepared by weighing carbon black powder and graphite powder in a mass ratio of (40-45):(55-60), mixing them by ball milling to obtain powder B, and then subjecting the powder B to low-temperature plasma treatment using O2 as a modifying gas to form a mixture of modified carbon black and modified graphite, thereby obtaining the modified thermal conductive material B; The thermal conductive material C is obtained by mixing nano-AlN and nano-GaN in a mass ratio of (60-65):(35-40) by ball milling; The modified fiber-reinforced material is obtained by mixing carbon fibers and SiC whiskers in a mass ratio of (55-60):(40-45) and performing surface modification on the mixture.

2. The high-performance cement system for deep geothermal development according to claim 1, characterized in that: When the modified composite high thermal conductivity material dispersion is sprayed on the surface of the modified fiber reinforced material, the spraying pressure is controlled to 0.3 MPa, and the distance between the spray gun and the surface of the modified fiber reinforced material is maintained at 14 cm-16 cm; after the spraying is completed, the sprayed material is sent to an infrared medium-temperature drying equipment and blown and mixed at a gas flow rate of 10 m / s for 5 minutes. After sufficient mixing, the high thermal conductivity and toughened composite material is obtained.

3. The high-performance cement system for deep geothermal development according to claim 1, characterized in that: The modified composite high thermal conductive material dispersion is prepared by adding water to a container equipped with a stirring device and stirring at a speed of 500±50 r / min, then sequentially adding nanocellulose fibers, xanthan gum and polycarboxylic acid, continuing stirring for 30 minutes, adding the modified composite high thermal conductive material, increasing the stirring speed to 800±50 r / min, and continuing stirring for 1 hour to obtain the modified composite high thermal conductive material dispersion.

4. A high-performance cementing system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The modified thermal conductive material A is prepared by weighing nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in a mass ratio of (40-50):(35-40):(10-15):(5-10), mixing them by ball milling, setting the ball milling speed to 300±50r / min and the ball milling time to 1h to obtain powder A, and then coating the obtained powder A with nano-SiO2 by a sol-gel method.

5. A high-performance cementing system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The specific process of coating powder A with nano-SiO2 using the sol-gel method is as follows: Take 5g of powder A, 50ml of deionized water, 150ml of anhydrous ethanol and 5ml of NH3·H2O; add them to a container with a reflux condenser and perform ultrasonic dispersion in a 75°C water bath. The ultrasonic power is set to 300W and the ultrasonic time is 30min. After the ultrasonic dispersion, add 4ml of TEOS. In a 75°C water bath environment, continue magnetic stirring at a speed of 500±50r / min for 2h to allow it to react uniformly. After the reaction is completed, filter by suction to obtain a solid powder; then wash the solid powder with anhydrous ethanol, isopropanol and deionized water in sequence to remove unreacted NH3·H2O and TEOS. Finally, the obtained solid powder is dried in an 85°C oven to obtain a multi-component composite metal oxide SiO2-coated nanomaterial, namely, modified thermal conductive material A.

6. A high-performance cementing system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The particle size of nano-CuO, nano-TiO2, nano-Sc2O3 and nano-Y2O3 in the raw materials of the modified thermal conductive material A is in the range of 50nm to 80nm.

7. The high-performance cement system for deep geothermal development according to claim 5, characterized in that: The solute mass fraction of the NH3·H2O is 25%.

8. A high-performance cement system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The modified thermal conductive material B is prepared by weighing carbon black powder and graphite powder in a mass ratio of (40~45):(55~60), mixing them by ball milling, with a ball milling speed of 300±50r / min and a ball milling time of 1h to obtain powder B. Then, O2 is used as a modifying gas, and the O2 gas flow rate is set to 80ml / min. The powder B is subjected to low-temperature plasma treatment, wherein the low-temperature plasma treatment temperature is 65°C and the treatment power is 150w, so that the powder B becomes a mixture of modified carbon black and modified graphite, thereby obtaining the modified thermal conductive material B.

9. A high-performance cementing system for deep geothermal development according to claim 8, characterized in that: Among the raw materials of the modified thermal conductive material B, the carbon black powder has a particle size range of 10 μm to 20 μm and a carbon content of more than 95%; the graphite powder has a natural flake structure, a particle size range of 10 μm to 50 μm, and a carbon content of more than 90%.

10. A high-performance cement system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The particle sizes of the nano-AlN and nano-GaN in the thermal conductive material C are both in the range of 60 nm to 100 nm.

11. A high-performance cementing system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The surface modification treatment steps of the modified fiber reinforced material are as follows: 10 g of a mixed fiber reinforced material prepared by mixing carbon fiber and SiC whisker in a mass ratio of (55-60):(40-45) was placed in 100 ml of deionized water and ultrasonically dispersed for 30 min at an ultrasonic power of 300 W in a 50°C water bath. 50 ml of sodium dodecylbenzenesulfonate was added to the dispersion, and ultrasonic dispersion was continued for 15 min. Then, 25 ml of N-(hydroxymethyl)acrylamide was added, and the pH value of the solution was adjusted to 5. The mixture was magnetically stirred at a speed of 400±50 r / min for 3 h and then cooled to room temperature. Finally, the mixture was filtered by suction, washed twice with deionized water, and vacuum dried at a drying temperature of 85°C to obtain a modified fiber reinforced material.

12. A high-performance cementing system for deep geothermal development according to claim 11, characterized in that: The mass volume concentration of the sodium dodecylbenzenesulfonate is 0.05 g / ml.

13. The high-performance cement system for deep geothermal development according to claim 11, characterized in that: The mass volume concentration of the N-(hydroxymethyl)acrylamide is 0.05 g / ml.

14. A high-performance cementing system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The carbon fiber is a mesophase pitch-based carbon fiber with a tensile strength of ≥1200 MPa, an elastic modulus of ≥200 GPa, a thermal conductivity of ≥900 W / (m·K), a fiber length controlled at 1 mm to 3 mm, and a fiber diameter range of 5 μm to 10 μm; the SiC whisker is β -SiC whiskers with diameters ranging from 0.1μm to 1μm and lengths ranging from 5μm to 30μm.

15. A high-performance cementing system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The average diameter of the nanocellulose fibers is 10 nm; the molecular weight of the xanthan gum is 4 million to 6 million; and the polycarboxylic acid is a polycarboxylic acid with maleic anhydride as the main chain and polyethers of different side chain lengths grafted thereon.

16. A high-performance cement system for deep geothermal development according to any one of claims 1 to 3, characterized in that: In the high-temperature reinforcing material, the SiO2 content in quartz sand is above 96%, and its particle fineness is above 200 mesh; the SiO2 content in dehydrated pyrophyllite is above 60%, the Al2O3 content is above 15%, and its particle fineness is above 300 mesh; the SiO2 content in the single crystal silicon by-product is above 98%; the powder particle size of ultrafine kaolin is above 600 mesh; the CaO content in dolomite is above 30%, the MgO content is above 10%, and the SiO2 content is above 10%, and its particle size is above 300 mesh.

17. A high-performance cement system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The low hydration heat cement has a dicalcium silicate content of not less than 42%, a tricalcium aluminate content of not more than 6%, a free calcium oxide content of not more than 1%, and a hydration heat of not more than 300 kJ / kg at 28 days.

18. A high-performance cement system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The suspension stabilizer comprises 7% sodium tannate, 8% sodium lignin sulfonate and 85% modified bentonite powder by weight.

19. A high-performance cementing system for deep geothermal development according to any one of claims 1 to 3, characterized in that: The dispersant is at least one of polystyrene sulfonate, polynaphthalene sulfonate, lignin sulfonate and ketone-aldehyde condensation polymer; the fluid loss additive is at least one of polyamide, polyvinyl alcohol and AMPS polymer; the retarder is at least one of tartrate, citric acid, boric acid and phosphate; and the defoamer is at least one of polypropylene alcohol, organosilicon and tributyl phosphate.

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