Efficient plugging and channeling prevention cement system for shale oil and gas development

Abstract

The application discloses a kind of shale oil and gas development with efficient leak stoppage anti-channeling cement system, it is related to shale oil and gas engineering material technical field.The cement system includes oil well cement 100 parts by mass, temperature-resistant reinforcing material 28~35 parts, lightening material 0~15 parts, leak stoppage material 7~15 parts, thixotropic material 0.2~0.6 parts, gas channeling prevention material 4~8 parts, micro-expansion material 1~3 parts, fluid loss additive 2~3.5 parts, retarder 1.5~2.5 parts, dispersant 0.2~0.5 parts, defoaming agent 0.2 parts;Liquid-solid ratio is 0.44~0.60, slurry density can be regulated in 1.50g / cm 3 ~1.90g / cm 3 Range.The application can improve the problems of slurry instability, poor plugging performance, weak plugging effect and insufficient engineering performance of leak stoppage slurry under high temperature conditions, meet the well cementing and leak stoppage construction requirements of complex conditions such as multi-scale fracture-cave leakage, narrow safety density window and the like of high temperature formation.

Description

Technical Field

[0001] This invention relates to the field of materials technology for shale oil and gas drilling, completion, cementing and workover engineering, and more specifically to a high-efficiency plugging and anti-channeling cement system for shale oil and gas development. Background Technology

[0002] Shale oil and gas, as an important component of unconventional oil and gas resources, has become a strategic focus of oil and gas exploration and development in my country. Shale oil and gas-rich areas, represented by the Sichuan Basin and the Ordos Basin, are gradually becoming the main replacement areas for increasing reserves and production. Its development relies heavily on long horizontal wells and staged fracturing technology. The reservoirs generally exhibit characteristics such as well-developed natural fractures, brittle rocks, low formation pressure capacity, and narrow safe density windows, easily leading to serious problems such as leakage and gas channeling during oil and gas development. The main shale oil and gas development blocks have complex geological conditions. In the Sichuan Basin, the Longmaxi Formation shale is buried at depths mostly above 3500m, with high formation temperatures. The upper Permian Maokou Formation and Qixia Formation limestone karst caves are well-developed, making them prone to fracture-cavity loss-of-return leakage. The target layer, the Longmaxi Formation, has highly developed microfractures, bedding fractures, and structural fractures, with fracture apertures ranging from micrometer-level pores to centimeter-level caves, forming a multi-scale fracture-cavity network. Leakage types include permeable seepage, intermittent severe leakage, and malignant loss-of-return leakage.

[0003] When formation loss occurs, the primary technical approach is formation sealing. Existing technologies have been extensively studied for cementing loss in shale gas wells. For example, the invention patent with publication number CN121591462A, entitled "A Composite Plugging Agent, Plugging Composition, and Plugging Cement Slurry for Shale Gas Formation Fractures," provides a composite plugging agent and plugging cement slurry specifically for shale gas formation fractures. This composite plugging agent is composed of bridging material, filling material, and end-capping material in a mass ratio of (1.2–1.4):0.5:(0.1–0.3). The bridging material consists of organic fibers with a length of 3–5 mm; the filling material consists of inert particles with a particle size of 35–280 μm and microsilica with a particle size of 0.15–1 μm; and the end-capping material consists of organic fibers with a length of 8–9 mm and walnut shell particles with a length of 3–5 mm. The bridging material in this patent is mainly organic fiber, which may undergo thermal degradation under high-temperature deep well conditions, limiting its temperature resistance. Furthermore, the gradation effect depends on precise control of the on-site slurry preparation process, making construction quality control relatively difficult.

[0004] For example, the invention patent with publication number CN117801795A, entitled "A cement slurry-type plugging material resistant to downhole fluid dilution and its preparation method and application", provides a cement slurry-type plugging material resistant to downhole fluid dilution. The components include oil well cement, spherical weighting agent, high temperature anti-dilution agent, high temperature anti-suspending agent, high temperature anti-retarding agent, high temperature anti-toughening agent and high temperature anti-flocculating agent.

[0005] For example, the invention patent with publication number CN117361944A, entitled "Pluging Cement Slurry and Its Application", uses G-grade oil well cement as the matrix and introduces 10-35 parts by weight of temperature-sensitive expansive material, supplemented with components such as filtration loss reducer and nano filler. In this patent, the temperature-sensitive expansive material is relatively sensitive to temperature response, and the expansion effect is difficult to guarantee in the leakage layer with variable temperature or low temperature, and the sealing effect on large-sized cracks may be limited.

[0006] For example, the invention patent with publication number CN116874234A, entitled "A drilling plugging cement composition, cement slurry system and preparation method thereof", provides a drilling plugging cement composition, which consists of plugging cement main material and anti-water dispersion additive, wherein the anti-water dispersion additive includes acrylamide-based water loss reducing agent and naphthalene sulfonic acid formaldehyde condensate; this patent mainly solves the problems of difficult cement slurry retention and alkaline water flushing, but the sealing strength may be insufficient for ultra-large leakage channels.

[0007] Existing plugging technologies for shale oil and gas development still suffer from common shortcomings: First, most plugging materials lack the ability to seal micro- and nano-scale fractures at multiple scales; second, the synergistic control of the thixotropy, gas channeling prevention, and micro-expansion properties of cement slurry systems is insufficient; third, the long-term performance of plugging materials under high-temperature conditions is difficult to meet the requirements of staged fracturing; and fourth, conventional plugging materials are mostly single rigid bridging particles or flexible fibers, lacking a cross-scale, holistic design approach. Most research still focuses on single-performance optimization, only able to seal single-scale fractures, with poor adaptability to multi-scale fractures and cavities, resulting in low success rates for single-pass plugging and high re-leakage rates. Therefore, there is an urgent need to develop a high-efficiency plugging cement system with excellent comprehensive performance, capable of simultaneously achieving efficient sealing, stable retention, gas channeling prevention, and good mechanical compatibility under complex leakage conditions. Summary of the Invention

[0008] To overcome the defects and shortcomings of existing technologies, this invention provides a high-efficiency plugging and anti-channeling cement system for shale oil and gas development. The purpose of this invention is to address the industry pain points of existing plugging technologies, such as poor adaptability to multi-scale fractures, insufficient synergistic control of multiple performance aspects, weak long-term high-temperature performance, and low success rate of first-time plugging. It achieves integrated functions including efficient plugging across all scales under complex leakage conditions in shale oil and gas wells, stable slurry retention, annular gas channeling prevention, and formation mechanical adaptation. This invention can significantly improve the problems of slurry instability, poor plugging performance, weak plugging effect, and insufficient engineering performance of existing plugging slurries under high-temperature conditions, meeting the cementing and plugging construction needs of complex conditions such as multi-scale fracture and cavity leakage in high-temperature formations and narrow safety density windows.

[0009] To address the problems existing in the prior art, the present invention is achieved through the following technical solution.

[0010] This invention provides a high-efficiency plugging and anti-channeling cement system for shale oil and gas development. The cement system comprises the following components by weight: 100 parts oil well cement, 28-35 parts heat-resistant reinforcing material, 0-15 parts weight-reducing material, 7-15 parts plugging material, 0.2-0.6 parts thixotropic material, 4-8 parts gas channeling prevention material, 1-3 parts micro-expansion material, 2-3.5 parts fluid loss reducing agent, 1.5-2.5 parts retarder, 0.2-0.5 parts dispersant, and 0.2 parts defoamer; The plugging material is prepared by uniformly mixing amphiphilic modified flexible material, amphiphilic modified rigid material and amphiphilic modified biomass material in a mass ratio of (35~40):(25~30):(30~35); The amphiphilic modified flexible material is formed by uniformly mixing and compounding modified xanthan gum, modified bitumen powder and modified nitrile rubber powder in a mass ratio of (30~35):(35~40):(25~30); The amphiphilic modified rigid material is made by mixing modified nano-hexagonal boron nitride and modified silicon carbide whiskers in a mass ratio of (50~55):(45~50); The amphiphilic modified composite biomass material is prepared by mixing corn cob powder and sawdust powder in a mass ratio of (6~8):(2~4) and then modifying it with amphiphilic material. The thixotropic material is prepared by mixing hydroxyethyl cellulose, nano-silica and modified sodium-based montmorillonite in a mass ratio of (5~10):(15~25):(70~80); The liquid-to-solid ratio of this cement system is 0.44~0.60. By adjusting and reducing the amount of material admixtures and the liquid-to-solid ratio, the paste density of the cement system is made to be 1.50 g / cm³. 3 ~1.90g / cm 3 Regulation within a specified range.

[0011] More preferably, the modified xanthan gum is prepared by the following method: S1-1. Xanthan gum is dispersed in anhydrous N,N-dimethylformamide. After oxygen is removed by nitrogen, ethylenediamine is added and stirred under ice bath conditions. Then sodium cyanoborohydride is added and heated to react. After post-treatment, primary modified xanthan gum is obtained. S1-2. Primary modified xanthan gum is dispersed in anhydrous N,N-dimethylformamide, triethylamine is added to adjust the pH, and α-bromoisobutyryl bromide is added dropwise under low temperature conditions to carry out the acylation reaction. After post-treatment, secondary modified xanthan gum is obtained. S1-3. Using secondary modified xanthan gum as a substrate, sodium 2-ethanesulfonate methacrylate, 3-(methacrylamido)phenylboronic acid, copper bromide, tris(2-dimethylaminoethyl)amine, N,N-dimethylformamide, and deionized water were first added. After stirring, removing oxygen, and sealing, the first stage of polymerization was initiated by blue light. Then, isobornyl methacrylate, adamantyl methacrylate, and vinyltriethoxysilane were added to the system. After removing oxygen and sealing, the second stage of polymerization was initiated by blue light. After post-treatment, modified xanthan gum was obtained.

[0012] More preferably, in step S1-1, the solid-liquid ratio of xanthan gum to anhydrous N,N-dimethylformamide is 1:(15~20); 500wt% of ethylenediamine is added, and the mixture is stirred for 30min in an ice bath at 0~3℃ and 200r / min; then sodium cyanoborohydride of equal mass to ethylenediamine is added, and the mixture is heated to 35℃ and reacted in the dark for 12h; after the reaction is completed, the mixture is precipitated with anhydrous ethanol, filtered, and then washed with a mixture of anhydrous ethanol and anhydrous N,N-methylformamide in a volume ratio of 5:5, and then vacuum dried at 35℃ for 24h.

[0013] In a further preferred embodiment, in steps S1-2, the solid-liquid ratio of primary modified xanthan gum to anhydrous N,N-dimethylformamide is 1:(20~25); triethylamine is added to adjust the pH to 8.0; α-bromoisobutyryl bromide of 2 times the mass of primary modified xanthan gum is added dropwise at a uniform rate over 2 hours under an ice bath at 0~3℃; after the addition is completed, the temperature is raised to 30℃ and the reaction is carried out in the dark for 8 hours; the reaction product is precipitated with ice-cold anhydrous ethanol, washed, and vacuum dried at 35℃ for 24 hours.

[0014] More preferably, in steps S1-3, secondary modified xanthan gum, sodium 2-ethanesulfonate methacrylate, 3-(methacrylamido)phenylboronic acid, copper bromide, tris(2-dimethylaminoethyl)amine, N,N-dimethylformamide, and deionized water are added sequentially in a mass ratio of 100:(0.3~0.5):(0.1~0.2):(0.05~0.1):(0.05~0.1):(0.5~1.0):100. The mixture is stirred uniformly at 200 rpm for 30 min at room temperature, and then nitrogen gas is introduced to remove oxygen for 20 min. After sealing, the mixture was placed under a blue light source and reacted at room temperature for 5 hours. Then, isobornyl methacrylate, adamantyl methacrylate, and vinyltriethoxysilane were added at a mass ratio of 7:2:1, with the total mass of the three being 350-400 wt% of the total mass of sodium 2-ethanesulfonate methacrylate and 3-(methacrylamido)phenylboronic acid. After purging with nitrogen for 10 minutes, the mixture was sealed and reacted under a blue light source at room temperature for 5 hours. The product was then poured into a 1:1 mixture of ice-anhydrous ethanol and acetone to precipitate, filtered, washed with anhydrous ethanol, and dried under vacuum at 35°C for 24 hours.

[0015] More preferably, the modified asphalt powder is prepared through the following steps: S2-1. Dry, pulverize, and sieve the asphalt to obtain ultrafine asphalt powder with D50≤50μm; prepare an ethanol buffer solution containing KH550 silane coupling agent. S2-2. The organomontmorillonite and the ultrafine asphalt powder are modified using the ethanol buffer solution to obtain modified organomontmorillonite and primary modified asphalt powder. S2-3. Mix the primary modified asphalt powder with modified organic montmorillonite, add octadecyl methacrylate, hydroxyethyl methacrylate, azobisisobutyronitrile and antioxidant 1076, and disperse at high speed at room temperature to obtain secondary modified ultrafine asphalt powder. S2-4. The modified asphalt powder is reacted under supercritical CO2, dried, pulverized, sieved, and then blended with fumed silica to obtain the modified asphalt powder.

[0016] In a further preferred embodiment, in step S2-1, 20 parts by mass of anhydrous ethanol are taken, 0.2 parts by mass of glacial acetic acid are added, the pH is adjusted to 5.0, and then 2.5 to 3.5 parts by mass of KH550 silane coupling agent are added. The mixture is stirred evenly at room temperature to obtain an ethanol buffer solution.

[0017] In a further preferred embodiment, in step S2-2, 10 parts by mass of organomontmorillonite are placed in a mixer, heated to 80°C and the rotation speed is adjusted to 1500 r / min. 4 vol%~6 vol% of the ethanol buffer solution prepared in step S2-1 is added dropwise, and after high-speed dispersion for 1 h, modified organomontmorillonite is obtained.

[0018] In a further preferred embodiment, in step S2-2, 100 parts by mass of ultrafine asphalt powder are placed in a mixer, the speed is adjusted to 500 r / min, the remaining ethanol buffer solution is added dropwise at room temperature for 20 min, after which the temperature is raised to 65°C, the speed is increased to 1000 r / min and stirred for 1 h, then poured out and vacuum dried at 60°C for 3 h to obtain primary modified ultrafine asphalt powder.

[0019] In a further preferred embodiment, in step S2-3, 100 parts by weight of primary modified ultrafine asphalt powder and 4.5-5.5 parts by weight of modified organomontmorillonite are added sequentially to a mixer and stirred at a speed of 1000 r / min; then the speed is increased to 200 r / min, and 6.5-7.0 parts by weight of octadecyl methacrylate, 4.0-4.5 parts by weight of hydroxyethyl methacrylate, 0.3-0.4 parts by weight of azobisisobutyronitrile, and 0.2-0.3 parts by weight of antioxidant 1076 are added and dispersed at high speed at room temperature to obtain secondary modified ultrafine asphalt powder.

[0020] More preferably, in step S2-4, 100 parts by mass of the secondary modified ultrafine asphalt powder are transferred to a reactor, high-purity CO2 is introduced to replace the air in the reactor, and the reactor is sealed. The temperature is increased to 120°C at 2°C / min, and the pressure is increased to 20MPa simultaneously to make the CO2 reach a supercritical state. The stirring speed is adjusted to 300r / min and the reaction is carried out for 3 hours. Then, heating and stirring are stopped and the pressure in the reactor is released. The reactants are vacuum dried at 140°C to remove unreacted residues. Then, they are pulverized and sieved to obtain powder with D50≤20μm. Then, the powder is poured into a mixer, 0.4~0.6 parts by mass of fumed silica are added, and the mixture is stirred at 1500r / min at room temperature to obtain the modified asphalt powder.

[0021] More preferably, the asphalt is any one of 50#, 70# and 90# asphalt.

[0022] More preferably, the modified nitrile rubber is prepared by the following steps: S3-1. Prepare an ethanol buffer solution containing KH570 silane coupling agent; prepare an epoxy resin solution containing bisphenol A type epoxy resin, cashew nut shell liquid modified phenolic resin and butyl acrylate; prepare an acrylate solution containing methacrylic acid and butyl acrylate; prepare an initiator solution containing potassium persulfate and deionized water. S3-2. Use an ethanol buffer containing KH570 silane coupling agent to perform coupling modification on ultrafine nitrile rubber powder to obtain primary modified ultrafine nitrile rubber powder. S3-3. Disperse the primary modified ultrafine nitrile rubber powder, add sodium dodecylbenzene sulfonate, octylphenol polyoxyethylene ether and sodium polyacrylate, heat to 80°C in a nitrogen atmosphere, and add epoxy resin liquid and 70% volume ratio of initiator liquid dropwise in sequence; then add acrylate liquid and the remaining initiator liquid dropwise to react. S3-4. After cooling to 40°C, dicyandiamide, 2-ethyl-4-methylimidazole and antioxidant 1010 are added and dispersed at high speed to form a uniformly dispersed emulsion. The emulsion is then spray-dried to obtain the modified nitrile rubber.

[0023] More preferably, in step S3-1, 35-40 parts by weight of anhydrous ethanol are taken, glacial acetic acid is added to adjust the pH to 4.0, 3.0-4.0 parts by weight of KH570 silane coupling agent are added, and the mixture is stirred at room temperature to obtain the ethanol buffer solution.

[0024] In a further preferred embodiment, in step S3-1, 40-43 parts by weight of bisphenol A type epoxy resin, 30-33 parts by weight of cashew nut shell liquid modified phenolic resin and 15-18 parts by weight of butyl acrylate are used, and the mixture is stirred evenly at room temperature to obtain epoxy resin liquid.

[0025] In a further preferred embodiment, in step S3-1, 14-17 parts by mass of methacrylic acid and 1-2 parts by mass of butyl acrylate are used, and the mixture is stirred evenly at room temperature to obtain an acrylate solution.

[0026] In a further preferred embodiment, in step S3-1, 1.0 to 1.2 parts by mass of potassium persulfate are added to 10 parts by mass of deionized water, and the mixture is stirred evenly at room temperature to obtain the initiator solution.

[0027] In a further preferred embodiment, in step S3-2, 100 parts by mass of ultrafine nitrile rubber are added to a dispersion vessel, and the ethanol buffer solution prepared in step S3-1 is added dropwise at a speed of 1500 r / min for 20 min. After the addition is complete, the temperature is raised to 60°C and the mixture is stirred for 1.5 h. After the reaction is complete, the product is washed with anhydrous ethanol to remove unreacted coupling agent and other impurities, and then vacuum dried at 60°C for 24 h to obtain primary modified ultrafine nitrile rubber powder.

[0028] In a further preferred embodiment, in step S3-3, 100 parts by weight of primary modified ultrafine nitrile rubber powder are added to a reaction vessel, followed by 250 parts by weight of deionized water, 2.5-3.0 parts by weight of sodium dodecylbenzenesulfonate, 1.0-1.5 parts by weight of octylphenol polyoxyethylene ether, and 0.5-1.0 parts by weight of sodium polyacrylate. The mixture is stirred at 300 r / min for 10 min at room temperature, then stirred at 5000 r / min for 30 min. Nitrogen gas is introduced into the reaction vessel to replace the air inside. The reaction vessel is heated to 80°C, and the stirring speed is reduced to 500 r / min. The epoxy resin solution prepared in step S3-1 and 70% of the initiator solution are added dropwise at a uniform rate for 1 hour. After the addition is completed, the reaction is kept at the temperature for 2 hours. Then, the acrylate solution and the remaining 30% of the initiator solution are added dropwise at a uniform rate for 0.5 hours. After the addition is completed, the reaction is kept at the temperature for 3 hours.

[0029] More preferably, in step S3-4, the reaction vessel is cooled to 40°C, and then 5.0-5.5 parts by weight of dicyandiamide, 0.2-0.4 parts by weight of 2-ethyl-4-methylimidazole, and 0.3-0.5 parts by weight of antioxidant 1010 are added. The rotation speed is adjusted to 3000 r / min, and the mixture is dispersed at high speed for 20 min to form a uniformly dispersed emulsion. The emulsion is then fed into a centrifugal spray dryer, with the inlet air temperature set to 130°C, the outlet air temperature set to 60°C, and the atomizing disc rotation speed set to 25000 r / min for continuous spray drying to obtain the modified nitrile rubber powder.

[0030] More preferably, the ultrafine nitrile rubber powder in step S3-2 has a mesh size ≥ 200 mesh.

[0031] More preferably, the modified nano-hexagonal boron nitride is prepared by the following method: S4-1. Nano-hexagonal boron nitride powder is subjected to plasma treatment followed by calcination; S4-2. Add the calcined nano-hexagonal boron nitride to anhydrous ethanol, add anhydrous acetic acid to adjust the pH, and modify it sequentially with KH550 silane coupling agent and 1H,1H,2H,2H-perfluorodecyltriethoxysilane. S4-3. The reactants obtained in step S4-2 are washed and dried to obtain the modified nano-hexagonal boron nitride.

[0032] More preferably, in step S4-1, the plasma treatment conditions are: treatment time 15~20 min, temperature 35℃, power 100 W, oxygen flow rate 20 sccm, vacuum degree 10 Pa; calcination temperature 500~550℃, calcination time 5 h.

[0033] More preferably, in step 4-2, the solid-liquid ratio of the calcined nano-hexagonal boron nitride powder to anhydrous ethanol is 1:(80~90); anhydrous acetic acid is added to adjust the pH to 5.0; in a 60°C water bath, 25~30wt% of calcined nano-hexagonal boron nitride KH550 silane coupling agent is added, and the reaction is maintained at this temperature for 2 hours; then, 10~15wt% of calcined nano-hexagonal boron nitride 1H,1H,2H,2H-perfluorodecyltriethoxysilane is added dropwise at a constant pressure dropping funnel over 1 hour, and the reaction is stirred for 5 hours after the addition is complete.

[0034] More preferably, the modified silicon carbide whiskers are prepared by the following method: S5-1. Take β-silicon carbide whiskers, heat them to 750~800℃ at 10℃ / min, and calcine them in air atmosphere for 2~3h to obtain primary modified silicon carbide whiskers. S5-2. Under room temperature conditions, the primary modified silicon carbide whiskers were dispersed in anhydrous ethanol at a solid-liquid ratio of 1:(50~60). Nitrogen gas was introduced to remove oxygen, and the mixture was ultrasonically dispersed for 20 min with stirring at 300 r / min. Anhydrous acetic acid was added to adjust the pH to 5.0. The mixture was then transferred to a 60℃ water bath, and 30~35 wt% of KH560 silane coupling agent (by weight of the primary modified silicon carbide whiskers) was added. The mixture was stirred and kept at the temperature for 4 h. After the reaction was completed, the mixture was washed with anhydrous ethanol and then vacuum dried to obtain secondary modified silicon carbide whiskers. S5-3. Under room temperature conditions, secondary modified silicon carbide whiskers were dispersed in N,N-dimethylformamide at a solid-liquid ratio of 1:(40~45). Nitrogen gas was introduced to remove oxygen, and the mixture was ultrasonically dispersed for 20 min with stirring at 300 r / min. Then, 25~30 wt% of triethylamine was added to the mixture. The mixture was then transferred to a water bath at 90℃ and stirred and kept at the temperature for 8 h. After the reaction was completed, the mixture was washed with deionized water and then vacuum dried to obtain the modified silicon carbide whiskers.

[0035] More preferably, in step S5-1, the diameter of the β-silicon carbide whisker is 0.1~0.5μm and the length is 5-20μm.

[0036] More preferably, the amphiphilic modified composite biomass material is prepared by the following method: S6-1. Take corn cobs and sawdust, dry them separately, crush them, and sieve them through a 200-mesh standard sieve to obtain corn cob powder and sawdust powder. S6-2. Mix corn cob powder and sawdust powder evenly at a mass ratio of (6~8):(2~4), add 50~55wt% of petroleum ether of the total amount of composite powder, and extract by Soxhlet extraction for 5 hours; filter dry by suction, add 50~55wt% of 85% ethanol solution of the total amount of composite powder and continue extraction for 3 hours; wash the product with anhydrous ethanol and then vacuum dry to obtain purified composite biomass powder; S6-3. Add the purified composite biomass powder to the alkaline alcohol solution at a solid-liquid ratio of 1:(28~33), purge with nitrogen to remove oxygen, seal, stir at 200 r / min at room temperature for 6~8 h, then raise the temperature to 60℃ and stir for another 2~3 h. After the reaction is complete, wash with deionized water and then vacuum dry to obtain activated composite biomass powder. S6-4. Using activated composite biomass powder as a substrate, phenol, glycidyl methacrylate, styrene, and N-hydroxymethylacrylamide are added at a mass ratio of 100:(25~30):(30~35):(8~12):(2~4). Deionized water is added to prepare a solution with a solid content of 20~25%. 0.8~1.0wt% of ammonium persulfate and 1.5~2.0wt% of sodium carbonate are added to the total amount of the system. The mixture is stirred evenly at room temperature. S6-5. Introduce nitrogen to purge oxygen, raise the temperature to 50°C, and stir the reaction at 300 r / min for 1-2 h. Then raise the temperature to 85°C and continue stirring the reaction for 2-3 h. After the reaction is completed, cool to room temperature, wash with anhydrous ethanol and deionized water in sequence, and then vacuum dry to obtain the amphiphilic modified composite biomass material.

[0037] More preferably, the alkaline alcohol solution is prepared by mixing a 10% NaOH solution and anhydrous ethanol at a volume ratio of (3~4):(7~6).

[0038] More preferably, the leak-sealing material is prepared by weighing amphiphilic modified flexible material, amphiphilic modified rigid material and amphiphilic modified biomass material according to the above mass ratio, placing them in a high-speed mixer, stirring at 1500 r / min for 20 min at room temperature, and mixing evenly to obtain the leak-sealing material.

[0039] More preferably, the modified sodium-based montmorillonite is prepared by the following method: S7-1. Take 100g of calcium-based montmorillonite, disperse it evenly in 1L of deionized water, add 5g of anhydrous sodium carbonate, heat to 65℃, stir and react at a constant temperature for 2h, wash with deionized water and dry to obtain sodium-based montmorillonite. S7-2. Take 50g of sodium-based montmorillonite prepared in step S7-1, disperse it in 1L of deionized water to form a uniform montmorillonite suspension, and adjust the pH to 8.5 with 0.5mol / L dilute hydrochloric acid. S7-3. Heat 500ml of deionized water to 75℃, then add 6g of dioctadecyl dimethyl ammonium chloride to the deionized water and stir at a constant temperature to dissolve, forming an aqueous solution of dioctadecyl dimethyl sodium chloride. S7-4. The aqueous solution of dioctadecyl dimethyl sodium chloride obtained in step S7-3 is added dropwise to the montmorillonite suspension obtained in step S7-2. The addition time is 30 min. After the addition is completed, the mixture is stirred at a constant temperature for 3 h. After the reaction is completed, the mixture is cooled to room temperature, centrifuged, washed multiple times with deionized water at 75 °C, and then vacuum dried and ground to obtain the modified sodium-based montmorillonite.

[0040] More preferably, the oil well cement is Grade G oil well cement, or oil well cement made by mixing Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:2.

[0041] More preferably, the heat-resistant reinforcing material is a mixture of quartz sand, microsilica, metakaolin, diabase powder and cordierite in a mass ratio of 60:18:12:5:5.

[0042] More preferably, the quartz sand has a SiO2 content ≥95% and a particle size ≥200 mesh; a microsilica SiO2 content ≥97% and a specific surface area ≥18000 m². 2 / kg; metakaolin SiO2 content ≥52%, Al2O3 content ≥38%, particle size ≥800 mesh; diabase powder SiO2 content ≥48%, Al2O3 content ≥15%, CaO content ≤8%, MgO content ≤6%, particle size ≥400 mesh; cordierite SiO2 content ≥49%, Al2O3 content ≥35%, MgO content ≥14%, particle size ≥325 mesh.

[0043] More preferably, the weight-reducing material is prepared by mixing hollow glass microspheres, diatomaceous earth and sepiolite in a mass ratio of 70:20:10.

[0044] More preferably, the bulk density of the hollow glass microspheres is 0.38 g / cm³. 3The compressive strength is ≥90MPa, and its D50 ≤55μm; the diatomaceous earth has a SiO2 content ≥90% and a bulk density of 0.40g / cm³. 3 Approximately 325 mesh in size; the sepiolite is β-sepiolite with a bulk density of 0.28 g / cm³. 3 Approximately 500 μm, SiO2 content ≥55%, MgO content ≥22%, loss on ignition ≤12%, and particle size ≥200 mesh.

[0045] More preferably, the anti-gas channeling material is a mixture of styrene-butadiene latex, nitrile latex, and nano-calcium carbonate in a mass ratio of 6:3:1.

[0046] More preferably, the styrene-butadiene latex is a carboxyl-modified styrene-butadiene latex with a solid content of 50%; the nitrile latex has a solid content of 50%; and the nano-calcium carbonate is activated nano-calcium carbonate treated with a titanate coupling agent with a particle size D50≤60nm.

[0047] More preferably, the micro-expansion material is prepared by mixing and compounding sulfoaluminate clinker, lightly calcined magnesia, zeolite powder and wollastonite fiber in a mass ratio of 4:3:2:1.

[0048] More preferably, the anhydrous calcium sulfoaluminate content in the sulfoaluminate clinker is ≥60%, and the specific surface area is ≥450 m². 2 / kg; the calcination temperature of the raw material for lightly calcined magnesium oxide is 800~1000℃, and the particle size is ≥200 mesh; the specific surface area of ​​the zeolite powder is ≥420m². 2 / kg; Wollastonite fiber length ≤150μm.

[0049] More preferably, the water loss reducing agent is at least one of polyamides, polyvinyl alcohols, AMPS polymers, sulfonated styrene-maleic anhydride copolymers, and organosilicon-modified polymers.

[0050] More preferably, the retarder is at least one of tartrates, citric acid, boric acid, phosphates, lignin sulfonates, naphthalene sulfonates, aminosulfonates, and AMPS copolymers.

[0051] More preferably, the dispersant is at least one of carboxylates, polystyrene sulfonates, polynaphthalene sulfonates, lignin sulfonates, and ketaldehyde condensates.

[0052] More preferably, the defoamer is at least one of polyacryl alcohol, organosilicon, and tributyl phosphate.

[0053] The liquid-to-solid ratio of the system described in this invention is 0.44~0.60. By adjusting and reducing the amount of material added and the liquid-to-solid ratio of the system, the slurry density can be made to be 1.50~1.90 g / cm³.3 Within a certain range, it can be adjusted and is suitable for sealing operations in formations with a formation temperature not exceeding 200℃. After curing for 24 hours, its compressive strength is above 14MPa. The slurry has good rheological stability and excellent anti-channeling and sealing performance. At the same time, the thickening time of the cement slurry can be adjusted according to actual needs, and it has the mechanical properties of high strength and low elastic modulus.

[0054] Compared with the prior art, the beneficial technical effects of this invention are as follows: 1. The plugging material of this invention undergoes amphiphilic modification treatment on all three types of plugging materials: flexible, rigid, and biomass, giving them both hydrophilic and oleophilic properties. This allows it to form a strong adsorption on the walls of oil-water two-phase fractures and karst caves, significantly improving the plugging effect and effective duration, and enhancing its resistance to formation fluid erosion. Furthermore, it constructs a multi-scale plugging structure ranging from nanometer to micrometer to millimeter, enabling simultaneous plugging of micro, medium, and large fractures in carbonate formations during shale oil and gas development. This significantly improves plugging efficiency compared to single-particle-size systems.

[0055] 2. The plugging material of this invention undergoes amphiphilic modification on all three core plugging material components: flexible, rigid, and biomass. This makes each material possess both hydrophilic and oleophilic properties, allowing it to be uniformly and stably dispersed in water-based systems, oil-based systems, and complex mixed fluid systems where oil and water coexist. It does not agglomerate, separate, or change its properties, and can simultaneously adapt to various complex formation leakage conditions such as porous, fractured, cavernous, and microfracture-pore composite types. This truly achieves multi-scenario and cross-system versatility, significantly improving the scenario adaptability and field applicability of the plugging material.

[0056] 3. The sealing material of this invention adopts a synergistic compound system of flexible materials, rigid materials, and biomass materials. The flexible materials possess excellent viscoelasticity and deformation-filling capabilities, adaptively filling fractures and pores according to changes in formation stress and temperature. At high temperatures, they can soften and mend gaps, improving sealing density. The rigid materials can quickly overlap within the leakage channels to form a stable three-dimensional skeleton structure, providing mechanical support for the overall sealing layer and significantly improving the pressure-bearing strength of the sealing body. The biomass materials can precisely fill the gaps and micro-voids in the skeleton, further enhancing sealing performance. These three materials synergistically construct a multi-level sealing structure of "rigid bridging – flexible filling – biomass sealing," significantly improving sealing success rate and pressure-bearing capacity, fundamentally reducing the risk of repeated formation leakage, and ensuring long-term sealing stability.

[0057] 4. This invention endows the sealing layer with self-healing properties, temperature resistance, and interfacial crosslinking by grafting dynamic covalent bonds, rigid groups, and siloxane groups onto modified xanthan gum; by using supercritical CO2 intercalation to modify asphalt powder, its upper limit of service temperature is increased from 120℃ to 200℃, while the elastic modulus is reduced by 30%; and by using modified silicon carbide whiskers to form a "needle-plate" interwoven network with hexagonal boron nitride, the wear resistance and shear strength of the sealing layer are improved.

[0058] 5. This invention significantly improves the temperature resistance, salt resistance, and structural stability of the sealing material through multiple chemical modifications: Modified xanthan gum grafting introduces sulfonic acid groups, hydrophobic salt-resistant groups, and boric acid active sites, maintaining good viscosity, elasticity, and filling performance even under harsh environments such as high temperature, high salt, and saturated salt water; Modified ultrafine asphalt powder undergoes supercritical CO2 treatment, organomontmorillonite intercalation, and functional monomer grafting, significantly improving its high-temperature resistance to softening and loss, and expanding its applicable temperature range; Modified nano-hexagonal boron nitride and modified silicon carbide whiskers undergo surface amphiphilic treatment, greatly improving their dispersibility in water-based and oil-based systems, preventing agglomeration and structural damage under high temperature and high salt environments, and maintaining a long-term bridging and supporting function. The overall material exhibits significantly better high-temperature resistance, shear resistance, and aging resistance than conventional sealing materials.

[0059] 6. The plugging material of this invention uses agricultural and forestry waste such as corn cobs and sawdust as biomass raw materials, realizing the resource utilization of solid waste. While reducing material costs, the material is non-toxic, harmless, and biodegradable, and does not pollute the formation, groundwater, or working environment. It is in line with the policy orientation of green environmental protection, low carbon energy conservation, and clean drilling and completion in oil and gas fields. All raw materials used are general industrial-grade raw materials, the modification process is mature and controllable, and can be scaled up industrially. There are no special and demanding requirements for reaction equipment. The production process is simple and energy consumption is moderate. It has the prospect of large-scale production and wide-ranging field application.

[0060] 7. The sealing material of the present invention has multiple functions, including physical bridging and sealing, in-situ filling and compaction, and interface bonding enhancement. After entering the leakage stratum, it can quickly form a solidified sealing layer with strength, toughness and sealing properties. It is firmly bonded to the rock interface of the stratum, is not easily eroded by fluids, and is not easily broken by pressure. The sealing layer has strong integrity and high stability, which can significantly reduce the number of sealing constructions and operating costs, and improve the efficiency of leakage control in complex strata.

[0061] 8. The plugging material of this invention exhibits excellent compatibility with various drilling fluids and cement slurry systems. Its addition does not disrupt the rheological properties, filtration performance, or stability of the original working fluid. It requires no significant adjustments to the on-site slurry system and can be directly applied in increased quantities. It is convenient to use, highly adaptable, and can meet the immediate plugging needs under various operating conditions such as drilling, well completion, well workover, and cementing. Through multi-level particle size compounding and amphiphilic structure design, the plugging material can simultaneously achieve large fracture bridging, medium fracture filling, and micropore sealing. It has excellent sealing effects on leakage channels of different scales, from micro-nano pores to millimeter-scale fractures, breaking through the limitation of traditional plugging materials that can only adapt to single-scale leakage. It has stronger comprehensive sealing capabilities and a wider range of applicable formations. The plugging material possesses excellent shear and erosion resistance, maintaining the integrity of the sealing structure even under high-speed fluid erosion and high pressure differentials. It is not prone to failure or backflow, and can continuously perform its sealing function during long-term production operations, effectively extending the effective sealing period, reducing repetitive operations, and lowering the overall cost of oil and gas field development.

[0062] 9. This invention uses a multi-component material compound to prepare a temperature-resistant reinforced system. Through the synergistic regulation of flexible plugging material and rigid reinforcing material, the elastic modulus of cement stone is significantly reduced compared with conventional cement, while maintaining high compressive strength. This achieves a mechanical match of high strength and low elastic modulus, which can effectively absorb formation stress, prevent the sealing layer from cracking and failing due to formation deformation, avoid secondary leakage problems, and simultaneously solve the problems of severe strength degradation, long-term durability and cracking of cement stone at high temperatures.

[0063] 10. This invention employs a compounded lightweight system, thixotropic system, anti-gas channeling system, and micro-expansion system, enabling the preparation of cement paste with a density range of 1.50~1.90 g / cm³. 3 It can precisely control the slurry density during sealing operations under different formation pressure coefficients; at the same time, the addition of thixotropic materials can ensure that the slurry has good settling stability and meet the rheological characteristics of static high viscosity becoming thinner during pumping; the synergistic application of micro-expansion materials and anti-gas channeling materials can also achieve good micro-expansion characteristics after cement stone sets, compensate for the chemical shrinkage of cement stone, eliminate gas channeling channels, and ensure excellent sealing effect and capability. Detailed Implementation

[0064] The technical solution of the present invention will be further described in detail below with reference to the embodiments. It should be noted that the embodiments described below are merely preferred embodiments of the present invention, and not all embodiments. Therefore, these embodiments are only described to help understand the present invention and do not constitute a limitation thereof. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0065] Example 1 This embodiment discloses a high-efficiency plugging and anti-channeling cement system for shale oil and gas development, comprising the following components by weight: 100 parts oil well cement, 30 parts heat-resistant reinforcing material, 3 parts weight-reducing material, 10 parts plugging material, 0.3 parts thixotropic material, 7 parts anti-channeling material, 2 parts micro-expansion material, 2.5 parts water loss reducing agent, 2 parts retarder, 0.4 parts dispersant, and 0.2 parts defoamer. The cement system has a slurry liquid-to-solid ratio of 0.55 and a slurry density of 1.65 g / cm³. 3 .

[0066] The oil well cement is Grade G oil well cement (HSR). The heat-resistant reinforcing material is prepared by mixing and compounding quartz sand, microsilica, metakaolin, diabase powder, and cordierite in a ratio of 60:18:12:5:5. Furthermore, the quartz sand has an SiO2 content ≥95% and a particle size ≥200 mesh; the microsilica has an SiO2 content ≥97% and a specific surface area ≥18000 m². 2 / kg; metakaolin SiO2 content ≥52%, Al2O3 content ≥38%, particle size ≥800 mesh; diabase powder SiO2 content ≥48%, Al2O3 content ≥15%, CaO content ≤8%, MgO content ≤6%, particle size ≥400 mesh; cordierite SiO2 content ≥49%, Al2O3 content ≥35%, MgO content ≥14%, particle size ≥325 mesh.

[0067] The weight-reducing material is prepared by mixing hollow glass microspheres, diatomaceous earth, and sepiolite in a ratio of 70:20:10. Furthermore, the bulk density of the hollow glass microspheres is 0.38 g / cm³. 3 The compressive strength is ≥90MPa, and its D50 ≤55μm; the diatomaceous earth has a SiO2 content ≥90% and a bulk density of 0.40g / cm³. 3 Approximately 325 mesh in size; the sepiolite is β-sepiolite with a bulk density of 0.28 g / cm³. 3 Approximately 500 μm, SiO2 content ≥55%, MgO content ≥22%, loss on ignition ≤12%, and particle size ≥200 mesh.

[0068] The sealing material is prepared by uniformly mixing amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material in a ratio of 35:30:35. Further, the amphiphilic modified flexible material is prepared by uniformly mixing modified xanthan gum, modified ultrafine asphalt powder, and modified ultrafine nitrile rubber powder in a mass ratio of 32.5:37.5:30; the amphiphilic modified rigid material is prepared by uniformly mixing modified nano-hexagonal boron nitride and modified silicon carbide whiskers in a mass ratio of 52.5:47.5; and the amphiphilic modified composite biomass material is prepared by further amphiphilic modification of a composite biomass material obtained by mixing corn cob powder and sawdust powder in a mass ratio of 7:3.

[0069] Specifically, the preparation process of the modified xanthan gum is as follows: S1-1. Xanthan gum and anhydrous N,N-dimethylformamide were added to a three-necked flask at a solid-liquid ratio of 1:17.5. The mixture was stirred at 200 r / min in a water bath at 35°C until completely dispersed. High-purity nitrogen was introduced for 10 min to purge oxygen. 500 wt% ethylenediamine (by weight of xanthan gum) was added to the solution. The mixture was stirred at 200 r / min in an ice bath at 0-3°C for 30 min. Sodium cyanoborohydride (by weight of ethylenediamine) was then added. The mixture was heated to 35°C and reacted in the dark for 12 h. After the reaction was completed, the product was precipitated in excess anhydrous ethanol. After filtration, the product was washed three times with a mixture of anhydrous ethanol and anhydrous N,N-dimethylformamide at a volume ratio of 5:5. The product was then vacuum dried at 35°C for 24 h to obtain primary modified xanthan gum. S1-2. Add primary modified xanthan gum and anhydrous N,N-dimethylformamide to a Schlenk flask at a solid-liquid ratio of 1:22.5. Stir at 200 rpm in a 30°C water bath until completely dissolved. Add triethylamine to adjust the pH of the solution to 8.0. Transfer to an ice bath and control the temperature at 0-3°C. Add α-bromoisobutyryl bromide at a uniform rate of 2 times the mass of primary modified xanthan gum over 2 hours using a constant pressure dropping funnel. After the addition is complete, raise the temperature to 30°C and react in the dark for 8 hours. After the reaction is complete, pour the product into ice-cold anhydrous ethanol to precipitate. After filtration, wash three times with anhydrous ethanol and dry under vacuum at 35°C for 24 hours to obtain secondary modified xanthan gum. S1-3, in a Schlenk flask, secondary modified xanthan gum, sodium 2-ethanesulfonate methacrylate, 3-(methacryloylamino)phenylboronic acid, copper bromide, tris(2-dimethylaminoethyl)amine, N,N-dimethylformamide, and deionized water were added according to a mass ratio of 100:0.4:0.15:0.075:0.075:0.75:100. The mixture was stirred at 200 rpm for 30 min at room temperature, then purged with nitrogen for 20 min to remove oxygen. The flask was then sealed and placed under a blue light source at room temperature for 5 h. Then, the solution was further... Isoborneol methacrylate, adamantyl methacrylate, and vinyltriethoxysilane (total mass of the three is 375 wt% of the total mass of sodium 2-ethanesulfonate methacrylate and 3-(methacryloylamino)phenylboronic acid) were added in a mass ratio of 7:2:1. After purging with nitrogen for 10 min, the mixture was sealed and reacted at room temperature under a blue light source for 5 h. After the reaction was completed, the product was poured into a 1:1 volume mixture of ice-anhydrous ethanol and acetone to precipitate. After filtration, the product was washed three times with anhydrous ethanol and dried under vacuum at 35 °C for 24 h to obtain modified xanthan gum.

[0070] Specifically, the modified asphalt powder is prepared through the following steps: S2-1. Take 70# asphalt and vacuum dry it at 120℃ for 4 hours. After pulverizing it with a universal pulverizer, sieve it through a 300-mesh standard sieve to obtain ultrafine asphalt powder with D50≤50μm. Take 20 parts by weight of anhydrous ethanol, add 0.2 parts by weight of glacial acetic acid to adjust the pH to 5.0, then add 3 parts by weight of KH550 silane coupling agent, stir evenly at room temperature to obtain a buffer solution. S2-2. Take 10 parts by weight of organomontmorillonite powder and put it into a mixer. Heat the mixture to 80°C and rotate at 1500 r / min. Add 5 vol% of the above-mentioned ethanol buffer solution dropwise. Disperse at high speed for 1 hour and then pour out the mixture to obtain modified organomontmorillonite. Take 100 parts by weight of ultrafine asphalt powder and put it into a mixer. Rotate the mixture at 500 r / min and add the remaining 95 vol% ethanol buffer solution dropwise at room temperature for 20 minutes. After the addition is completed, heat the mixture to 65°C and adjust the rotation speed to 1000 r / min. Stir and react for 1 hour and then pour out the mixture. Dry it under vacuum at 60°C for 3 hours to obtain primary modified ultrafine asphalt powder. S2-3. In a mixer, add 100 parts by weight of primary modified ultrafine asphalt powder and 5 parts by weight of modified organic montmorillonite in sequence, and mix at 1000 r / min for 5 min. Increase the speed to 2000 r / min, add 6.75 parts by weight of octadecyl methacrylate, 4.25 parts by weight of hydroxyethyl methacrylate, 0.35 parts by weight of azobisisobutyronitrile, and 0.25 parts by weight of antioxidant 1076, and add for 15 min. Disperse at room temperature and speed for 30 min to obtain secondary modified ultrafine asphalt powder. S2-4. Transfer 100 parts by mass of the secondary modified ultrafine asphalt powder into a reactor. After purging the reactor with high-purity CO2 for 10 minutes, seal the reactor and raise the temperature to 120°C at 2°C / min. Simultaneously, increase the pressure to 20MPa to bring the CO2 to a supercritical state. Stir the reaction at 300r / min for 3 hours. Stop heating and stirring, slowly release the pressure inside the reactor, and vacuum dry the reactants at 140°C for 2 hours to remove unreacted residues. After pulverizing, sieve the powder through a 500-mesh standard sieve to obtain powder with D50≤25μm. Pour the powder into a mixer, add 0.5 parts by mass of fumed silica, stir at 1500r / min at room temperature for 10 minutes, and then pour out the mixture to obtain the modified ultrafine asphalt powder.

[0071] Specifically, the modified nitrile rubber is prepared through the following steps: S3-1. Take 37.5 parts by weight of anhydrous ethanol, add glacial acetic acid to adjust the pH to 4.0, then add 3.5 parts by weight of KH570 silane coupling agent, stir at room temperature for 30 minutes to obtain a buffer solution; prepare three groups of solutions A, B, and C: Solution A (epoxy resin solution) is prepared by stirring 41.5 parts by weight of bisphenol A type epoxy resin, 31.5 parts by weight of cashew nut shell liquid modified phenolic resin, and 16.5 parts by weight of butyl acrylate at room temperature until homogeneous; Solution B (acrylate solution) is prepared by stirring 15.5 parts by weight of methacrylic acid and 1.5 parts by weight of butyl acrylate at room temperature until homogeneous; Solution C (initiator solution) is prepared by dissolving 1.1 parts by weight of potassium persulfate in 10 parts by weight of deionized water at room temperature until homogeneous. S3-2. Take 100 parts by weight of 200 mesh ultrafine nitrile rubber powder and add it to a high-speed dispersion vessel. Add the above buffer solution dropwise at a speed of 1500 r / min for 20 min. After the addition is completed, heat to 60℃ and stir for 1.5 h. Wash the product three times with anhydrous ethanol and dry it under vacuum at 60℃ for 24 h to obtain primary modified ultrafine nitrile rubber powder. S3-3. Take 100 parts by weight of primary modified ultrafine nitrile rubber powder and add it to the reactor. Then add 250 parts by weight of deionized water, 2.75 parts by weight of sodium dodecylbenzenesulfonate, 1.25 parts by weight of octylphenol polyoxyethylene ether, and 0.75 parts by weight of sodium polyacrylate in sequence. Stir at 300 rpm for 10 min at room temperature, and then stir at 5000 rpm for 30 min. Purge the reactor with high-purity nitrogen to replace the air for 10 min. Raise the temperature to 80°C and reduce the stirring speed to 500 rpm. First, add solution A dropwise at a uniform rate, and then add solution C at 70% of its volume ratio. The dropwise addition time is 1 h. After the dropwise addition is completed, keep the reaction temperature at 2 h. Then add solution B and the remaining 30% of solution C dropwise for 0.5 h. After the dropwise addition is completed, keep the reaction temperature at 3 h. S3-4. Reduce the temperature of the reactor to 40℃, add 5.25 parts by weight of dicyandiamide, 0.3 parts by weight of 2-ethyl-4-methylimidazole, and 0.4 parts by weight of antioxidant 1010, and disperse at high speed for 20 minutes at a speed of 3000 r / min to obtain a uniform emulsion; send the emulsion into a centrifugal spray dryer, set the inlet air temperature to 130℃, the outlet air temperature to 60℃, and the atomizing disc speed to 25000 r / min, and spray dry continuously to obtain modified ultrafine nitrile rubber powder.

[0072] Specifically, the modified nano-hexagonal boron nitride is prepared by the following method: S4-1. Place nano-hexagonal boron nitride powder in the cavity of a low-temperature plasma treatment instrument and treat it for 17.5 min at 35℃, power 100W, oxygen flow rate 20sccm, and vacuum degree 10Pa. Then, place the treated powder into a muffle furnace and calcine it to 525℃ at 5℃ / min in an air atmosphere for 5 h. S4-2. In a three-necked flask, calcined nano-hexagonal boron nitride powder was added to anhydrous ethanol at a solid-liquid ratio of 1:85. Nitrogen gas was introduced to remove oxygen for 10 min, and the mixture was ultrasonically dispersed for 20 min under stirring at 300 r / min. Anhydrous acetic acid was added to adjust the pH to 5.0. The mixture was then transferred to a 60℃ water bath, and 27.5 wt% KH550 silane coupling agent of nano-hexagonal boron nitride was added. The mixture was stirred and kept at the temperature for 2 h. 12.5 wt% 1H,1H,2H,2H-perfluorodecyltriethoxysilane of nano-hexagonal boron nitride was added dropwise over 1 h using a constant pressure dropping funnel. After the addition was completed, the mixture was stirred and reacted for 5 h. S4-3. After filtering the reaction product, it was washed three times by centrifugation with anhydrous ethanol and dried under vacuum at 60°C for 24 hours to obtain modified nano-hexagonal boron nitride.

[0073] Specifically, the modified silicon carbide whiskers are prepared by the following method: S5-1. Take β-silicon carbide whiskers with a diameter of 0.1~0.5μm and a length of 5~20μm and place them in a muffle furnace. Heat the furnace to 775℃ at 10℃ / min and calcine in air atmosphere for 2.5h to obtain primary modified silicon carbide whiskers. S5-2. At room temperature, primary modified silicon carbide whiskers and anhydrous ethanol were added to a three-necked flask at a solid-liquid ratio of 1:55. Nitrogen gas was introduced to remove oxygen for 10 min, and the mixture was ultrasonically dispersed at 300 r / min for 20 min. Anhydrous acetic acid was added to adjust the pH to 5.0. The mixture was then transferred to a 60℃ water bath, and 32.5 wt% KH560 silane coupling agent (by weight of the whiskers) was added. The mixture was stirred and kept at this temperature for 4 h. The product was washed three times by centrifugation with anhydrous ethanol and dried under vacuum at 60℃ for 24 h to obtain secondary modified silicon carbide whiskers. S5-3. At room temperature, secondary modified silicon carbide whiskers and N,N-dimethylformamide were added to a three-necked flask at a solid-liquid ratio of 1:42.5. Nitrogen gas was introduced to purge oxygen for 10 min, and the mixture was ultrasonically dispersed at 300 r / min for 20 min. Then, 27.5 wt% p-aminobenzenesulfonic acid and 27.5 wt% triethylamine were added. The mixture was transferred to a 90°C water bath and stirred and kept at this temperature for 8 h. The product was washed three times with deionized water and dried under vacuum at 80°C for 48 h to obtain modified silicon carbide whiskers.

[0074] Specifically, the amphiphilic modified composite biomass material is prepared by the following method: S6-1. Take corn cobs and sawdust, rinse and filter them three times with tap water, dry them in a 60℃ forced-air drying oven for 24 hours, pulverize them with a high-speed universal pulverizer, and then sieve them through a 200-mesh standard sieve to obtain corn cob powder and sawdust powder. S6-2. Mix corn cob powder and sawdust powder evenly at a mass ratio of 7:3. Add 52.5 wt% petroleum ether to the total mass of the composite powder and extract for 5 hours using Soxhlet extraction to remove oils and waxes. After filtration, add 52.5 wt% 85% ethanol solution to the total mass of the composite powder and continue extraction for 3 hours to remove soluble components. Wash the product twice with anhydrous ethanol and vacuum dry at 60℃ for 24 hours to obtain purified composite biomass powder. S6-3. Add purified composite biomass powder and alkaline alcohol solution (10% NaOH solution and anhydrous ethanol at a volume ratio of 3.5:6.5) to a three-necked flask at a solid-liquid ratio of 1:30.5. Purge the flask with nitrogen gas for 10 min to remove oxygen, then seal it. Stir the mixture at 200 r / min for 7 h at room temperature, then raise the temperature to 60 °C and stir for another 2.5 h. Wash the product three times with deionized water and dry it under vacuum at 60 °C for 24 h to obtain activated composite biomass powder. S6-4. In a three-necked flask, add activated composite biomass powder, phenol, glycidyl methacrylate, styrene, and N-hydroxymethylacrylamide in a mass ratio of 100:27.5:32.5:10:3, and add deionized water to prepare a solution with a solid content of 22.5%. Add 0.9 wt% of ammonium persulfate and 1.75 wt% of sodium carbonate, and stir evenly at room temperature. S6-5. Nitrogen gas was introduced into the bottle to remove oxygen for 10 min. The temperature was raised to 50℃ and stirred at 300 r / min for 1.5 h. The temperature was then raised to 85℃ and stirred for another 2.5 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed three times with anhydrous ethanol and then three times with deionized water. It was then dried under vacuum at 60℃ for 24 h to obtain the amphiphilic modified biomass material.

[0075] Furthermore, according to the above proportions, weigh the amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material and put them into a high-speed mixer. Stir at 1500 r / min for 20 min at room temperature until they are evenly mixed to obtain the plugging material.

[0076] The thixotropic material is prepared by mixing hydroxyethyl cellulose, nano-silica, and modified sodium-based montmorillonite in a ratio of 5:20:75. Furthermore, the modified sodium-based montmorillonite is obtained by the following method: S7-1. Take 100g of calcium-based montmorillonite, disperse it evenly in 1L of deionized water, add 5g of anhydrous sodium carbonate, heat to 65℃, stir and react at a constant temperature for 2h, wash twice with deionized water and dry to obtain sodium-based montmorillonite. S7-2. Take 50g of sodium montmorillonite and disperse it in 1L of deionized water to form a uniform montmorillonite suspension. Adjust the pH to about 8.5 with 0.5mol / L dilute hydrochloric acid. S7-3. Heat 500ml of deionized water to 75℃, then add 6g of dioctadecyl dimethyl ammonium chloride, stir at a constant temperature to dissolve, and form an aqueous solution of dioctadecyl dimethyl ammonium chloride. S7-4. The aqueous solution of dioctadecyl dimethyl ammonium chloride was slowly added dropwise to the montmorillonite suspension through a constant pressure dropping funnel for 30 minutes. After the addition was completed, the mixture was stirred at a constant temperature for 3 hours. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed with deionized water at 75°C more than 5 times, and then vacuum dried and ground to obtain the modified sodium-based montmorillonite.

[0077] The anti-gas channeling material is composed of styrene-butadiene latex, nitrile-butadiene latex, and nano-calcium carbonate in a ratio of 6:3:1. Further, the styrene-butadiene latex is carboxyl-modified styrene-butadiene latex with a solid content of 50%; the nitrile-butadiene latex has a solid content of 50%; and the nano-calcium carbonate is activated nano-calcium carbonate treated with a titanate coupling agent, with a particle size D50 ≤ 60 nm.

[0078] The micro-expansion material is prepared by mixing and compounding sulfoaluminate clinker, lightly calcined magnesia, zeolite powder, and wollastonite fiber in a ratio of 4:3:2:1. Furthermore, the sulfoaluminate clinker contains ≥60% anhydrous calcium sulfoaluminate and has a specific surface area ≥450 m². 2 / kg; the calcination temperature of the raw material for lightly calcined magnesium oxide is 800~1000℃, and the particle size is ≥200 mesh; the specific surface area of ​​the zeolite powder is ≥420m². 2 / kg; Wollastonite fiber length ≤150μm.

[0079] The water loss reducing agent is G33S. The retarder is GH-9. The dispersant is USZ. The defoamer is XP-1.

[0080] Example 2 This embodiment discloses a high-efficiency plugging and anti-channeling cement system for shale oil and gas development, comprising the following components by weight: 100 parts oil well cement, 28 parts heat-resistant reinforcing material, 0 parts weight-reducing material, 15 parts plugging material, 0.2 parts thixotropic material, 6 parts anti-channeling material, 3 parts micro-expansion material, 3 parts water loss reducing agent, 2.5 parts retarder, 0.35 parts dispersant, and 0.2 parts defoamer. The cement system has a slurry liquid-to-solid ratio of 0.44 and a slurry density of 1.90 g / cm³. 3 .

[0081] The oil well cement is the same as in Example 1; the reinforcing material is the same as in Example 1.

[0082] The sealing material is prepared by uniformly mixing amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material in a ratio of 40:25:35. Further, the amphiphilic modified flexible material is prepared by uniformly mixing modified xanthan gum, modified ultrafine asphalt powder, and modified ultrafine nitrile rubber powder in a mass ratio of 30:40:30; the amphiphilic modified rigid material is prepared by uniformly mixing modified nano-hexagonal boron nitride and modified silicon carbide whiskers in a mass ratio of 50:50; and the amphiphilic modified composite biomass material is prepared by further amphiphilic modification of a composite biomass material obtained by mixing corn cob powder and sawdust powder in a mass ratio of 6:4.

[0083] Specifically, the preparation process of the modified xanthan gum is as follows: S1-1. Add xanthan gum and anhydrous N,N-dimethylformamide to a three-necked flask at a solid-liquid ratio of 1:15. Stir at 200 r / min in a water bath at 35°C until completely dispersed. Purge with high-purity nitrogen for 10 min to remove oxygen. Add 500 wt% ethylenediamine (by weight of xanthan gum) to the solution. Stir at 200 r / min in an ice bath at 0-3°C for 30 min. Add sodium cyanoborohydride (by weight of ethylenediamine) and heat to 35°C. React in the dark for 12 h. After the reaction, precipitate the product in excess anhydrous ethanol. Filter the product and wash three times with a mixture of anhydrous ethanol and anhydrous N,N-dimethylformamide at a volume ratio of 5:5. Dry under vacuum at 35°C for 24 h to obtain primary modified xanthan gum. S1-2. Add primary modified xanthan gum and anhydrous N,N-dimethylformamide to a Schlenk flask at a solid-liquid ratio of 1:20. Stir at 200 rpm in a 30°C water bath until completely dissolved. Add triethylamine to adjust the pH of the solution to 8.0. Transfer to an ice bath and control the temperature at 0-3°C. Add α-bromoisobutyryl bromide at a uniform rate of 2 times the mass of primary modified xanthan gum over 2 hours using a constant pressure dropping funnel. After the addition is complete, raise the temperature to 30°C and react in the dark for 8 hours. After the reaction is complete, pour the product into ice-cold anhydrous ethanol to precipitate. After filtration, wash three times with anhydrous ethanol and dry under vacuum at 35°C for 24 hours to obtain secondary modified xanthan gum. S1-3. In a Schlenk flask, add secondary modified xanthan gum, sodium 2-ethanesulfonate methacrylate, 3-(methacryloylamino)phenylboronic acid, copper bromide, tris(2-dimethylaminoethyl)amine, N,N-dimethylformamide, and deionized water in a mass ratio of 100:0.3:0.1:0.05:0.05:0.5:100. Stir at 200 rpm for 30 min at room temperature, purge with nitrogen for 20 min to remove oxygen, seal, and react under a blue light source at room temperature for 5 h. Then add to the solution in a mass ratio of... Isobornyl methacrylate, adamantyl methacrylate, and vinyltriethoxysilane (total mass of the three is 350 wt% of the total mass of sodium 2-ethanesulfonate methacrylate and 3-(methacryloylamino)phenylboronic acid) were added in a ratio of 7:2:1. After purging with nitrogen for 10 min, the mixture was sealed and reacted at room temperature under a blue light source for 5 h. After the reaction was completed, the product was poured into a 1:1 volume mixture of ice-anhydrous ethanol and acetone to precipitate. After filtration, the product was washed three times with anhydrous ethanol and dried under vacuum at 35 °C for 24 h to obtain modified xanthan gum.

[0084] Specifically, the modified asphalt powder is prepared through the following steps: S2-1. Take 50# asphalt and vacuum dry it at 120℃ for 4 hours. After pulverizing it with a universal pulverizer, sieve it through a 300-mesh standard sieve to obtain ultrafine asphalt powder with D50≤50μm. Take 20 parts by weight of anhydrous ethanol, add 0.2 parts by weight of glacial acetic acid to adjust the pH to 5.0, and then add 2.5 parts by weight of KH550 silane coupling agent. Stir evenly at room temperature to obtain a buffer solution. S2-2. Take 10 parts by weight of organomontmorillonite powder and put it into a mixer. Heat the mixture to 80°C and rotate at 1500 r / min. Add 4 vol% of the above-mentioned ethanol buffer solution dropwise. Disperse at high speed for 1 hour and then pour out the mixture to obtain modified organomontmorillonite. Take 100 parts by weight of ultrafine asphalt powder and put it into a mixer. Rotate the mixture at 500 r / min and add the remaining 96 vol% of the above-mentioned ethanol buffer solution dropwise at room temperature for 20 minutes. After the dropwise addition is completed, heat the mixture to 65°C and adjust the rotation speed to 1000 r / min. Stir and react for 1 hour and then pour out the mixture. Dry it under vacuum at 60°C for 3 hours to obtain primary modified ultrafine asphalt powder. S2-3. In a mixer, add 100 parts by weight of primary modified ultrafine asphalt powder and 4.5 parts by weight of modified organomontmorillonite in sequence, and mix at 1000 r / min for 5 min. Increase the speed to 2000 r / min, add 6.5 parts by weight of octadecyl methacrylate, 4.0 parts by weight of hydroxyethyl methacrylate, 0.3 parts by weight of azobisisobutyronitrile, and 0.2 parts by weight of antioxidant 1076, and add for 15 min. Disperse at room temperature and speed for 30 min to obtain secondary modified ultrafine asphalt powder. S2-4. Transfer 100 parts by mass of the secondary modified ultrafine asphalt powder into a reactor. After purging the reactor with high-purity CO2 for 10 minutes, seal the reactor and raise the temperature to 120°C at 2°C / min. Simultaneously, increase the pressure to 20MPa to bring the CO2 to a supercritical state. Stir the reaction at 300r / min for 3 hours. Stop heating and stirring, slowly release the pressure inside the reactor, and vacuum dry the reactants at 140°C for 2 hours to remove unreacted residues. After pulverizing, sieve the powder through a 500-mesh standard sieve to obtain powder with D50≤25μm. Pour the powder into a mixer, add 0.4 parts by mass of fumed silica, stir at 1500r / min at room temperature for 10 minutes, and then pour out the mixture to obtain the modified ultrafine asphalt powder.

[0085] Specifically, the modified nitrile rubber is prepared through the following steps: S3-1. Take 35 parts by weight of anhydrous ethanol, add glacial acetic acid to adjust the pH to 4.0, then add 3.0 parts by weight of KH570 silane coupling agent, stir at room temperature for 30 minutes to obtain a buffer solution; prepare three groups of solutions A, B, and C: Solution A is prepared by stirring 40 parts by weight of bisphenol A type epoxy resin, 30 parts by weight of cashew nut shell liquid modified phenolic resin, and 15 parts by weight of butyl acrylate at room temperature until homogeneous; Solution B is prepared by stirring 14 parts by weight of methacrylic acid and 1 part by weight of butyl acrylate at room temperature until homogeneous; Solution C is prepared by dissolving 1.0 part by weight of potassium persulfate in 10 parts by weight of deionized water at room temperature until homogeneous. S3-2. Take 100 parts by weight of 200 mesh ultrafine nitrile rubber powder and add it to a high-speed dispersion vessel. Add the above buffer solution dropwise at a speed of 1500 r / min for 20 min. After the addition is completed, heat to 60℃ and stir for 1.5 h. Wash the product three times with anhydrous ethanol and dry it under vacuum at 60℃ for 24 h to obtain primary modified ultrafine nitrile rubber powder. S3-3. Take 100 parts by weight of primary modified ultrafine nitrile rubber powder and add it to the reactor. Then add 250 parts by weight of deionized water, 2.5 parts by weight of sodium dodecylbenzenesulfonate, 1.0 part by weight of octylphenol polyoxyethylene ether, and 0.5 parts by weight of sodium polyacrylate in sequence. Stir at 300 r / min at room temperature for 10 min, and then stir at 5000 r / min for 30 min. Purge the reactor with high-purity nitrogen to replace the air for 10 min. Raise the temperature to 80℃ and reduce the stirring speed to 500 r / min. First, add solution A dropwise at a uniform rate, and then add solution C at 70% of the volume ratio. The dropwise addition time is 1 h. After the dropwise addition is completed, keep the reaction temperature at 2 h. Then add solution B and the remaining 30% of solution C dropwise. The dropwise addition time is 0.5 h. After the dropwise addition is completed, keep the reaction temperature at 3 h. S3-4. Reduce the temperature of the reactor to 40℃, add 5.0 parts by weight of dicyandiamide, 0.2 parts by weight of 2-ethyl-4-methylimidazole, and 0.3 parts by weight of antioxidant 1010. Adjust the speed to 3000 r / min and disperse at high speed for 20 min to obtain a uniform emulsion. Send the emulsion into a centrifugal spray dryer, set the inlet air temperature to 130℃, the outlet air temperature to 60℃, and the atomizing disc speed to 25000 r / min, and spray dry continuously to obtain modified ultrafine nitrile rubber powder.

[0086] Specifically, the modified nano-hexagonal boron nitride is prepared by the following method: S4-1. Place nano-hexagonal boron nitride powder in the cavity of a low-temperature plasma treatment instrument and treat it for 15 min at 35℃, power 100W, oxygen flow rate 20sccm, and vacuum degree 10Pa. Then, place the treated powder into a muffle furnace and calcine it to 500℃ at 5℃ / min in an air atmosphere for 5 h. S4-2. In a three-necked flask, calcined nano-hexagonal boron nitride powder was added to anhydrous ethanol at a solid-liquid ratio of 1:80. Nitrogen gas was introduced to remove oxygen for 10 min, and the mixture was ultrasonically dispersed for 20 min under stirring at 300 r / min. Anhydrous acetic acid was added to adjust the pH to 5.0. The mixture was then transferred to a 60℃ water bath, and 25 wt% KH550 silane coupling agent of nano-hexagonal boron nitride was added. The mixture was stirred and kept at the temperature for 2 h. 10 wt% 1H,1H,2H,2H-perfluorodecyltriethoxysilane of nano-hexagonal boron nitride was added dropwise over 1 h using a constant pressure dropping funnel. After the addition was completed, the mixture was stirred and reacted for 5 h. S4-3. After filtering the reaction product, it was washed three times by centrifugation with anhydrous ethanol and dried under vacuum at 60°C for 24 hours to obtain modified nano-hexagonal boron nitride.

[0087] Specifically, the modified silicon carbide whiskers are prepared by the following method: S5-1. Take β-silicon carbide whiskers with a diameter of 0.1~0.5μm and a length of 5~20μm and place them in a muffle furnace. Heat the furnace to 750℃ at 10℃ / min and calcine in air atmosphere for 2h to obtain primary modified silicon carbide whiskers. S5-2. At room temperature, primary modified silicon carbide whiskers and anhydrous ethanol were added to a three-necked flask at a solid-liquid ratio of 1:50. Nitrogen gas was introduced to remove oxygen for 10 min, and the mixture was ultrasonically dispersed at 300 r / min for 20 min. Anhydrous acetic acid was added to adjust the pH to 5.0. The mixture was then transferred to a 60℃ water bath, and 30 wt% of KH560 silane coupling agent (by weight of the whiskers) was added. The mixture was stirred and kept at this temperature for 4 h. The product was washed three times by centrifugation with anhydrous ethanol and dried under vacuum at 60℃ for 24 h to obtain secondary modified silicon carbide whiskers. S5-3. At room temperature, secondary modified silicon carbide whiskers and N,N-dimethylformamide were added to a three-necked flask at a solid-liquid ratio of 1:40. Nitrogen gas was introduced to remove oxygen for 10 min, and the mixture was ultrasonically dispersed at 300 r / min for 20 min. Then, 25 wt% p-aminobenzenesulfonic acid and 25 wt% triethylamine were added. The mixture was transferred to a 90°C water bath and stirred and kept at the temperature for 8 h. The product was washed three times with deionized water and dried under vacuum at 80°C for 48 h to obtain modified silicon carbide whiskers.

[0088] Specifically, the preparation process of the amphiphilic modified biomass material is as follows: S6-1. Take corn cobs and sawdust, rinse and filter them three times with tap water, dry them in a 60℃ forced-air drying oven for 24 hours, pulverize them with a high-speed universal pulverizer, and then sieve them through a 200-mesh standard sieve to obtain corn cob powder and sawdust powder. S6-2. Mix corn cob powder and sawdust powder evenly at a mass ratio of 6:4. Add 50wt% petroleum ether to the total mass of the composite powder and extract for 5 hours using Soxhlet extraction to remove oils and waxes. After filtration, add 50wt% 85% ethanol solution to the total mass of the composite powder and continue extraction for 3 hours to remove soluble components. Wash the product twice with anhydrous ethanol and vacuum dry at 60℃ for 24 hours to obtain purified composite biomass powder. S6-3. Add purified composite biomass powder and alkaline alcohol solution (10% NaOH solution and anhydrous ethanol at a volume ratio of 3:7) to a three-necked flask at a solid-liquid ratio of 1:28. Purge the flask with nitrogen gas for 10 min to remove oxygen, then seal it. Stir the mixture at 200 r / min for 6 h at room temperature, then raise the temperature to 60 °C and stir for another 2 h. Wash the product three times with deionized water and dry it under vacuum at 60 °C for 24 h to obtain activated composite biomass powder. S6-4. In a three-necked flask, add activated composite biomass powder, phenol, glycidyl methacrylate, styrene, and N-hydroxymethylacrylamide in a mass ratio of 100:25:30:8:2, and add deionized water to prepare a solution with a solid content of 20%. Add 0.8 wt% of ammonium persulfate and 1.5 wt% of sodium carbonate, and stir evenly at room temperature. S6-5. Nitrogen gas was introduced into the bottle to remove oxygen for 10 min. The temperature was raised to 50℃ and stirred at 300 r / min for 1 h. The temperature was then raised to 85℃ and stirred for another 2 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed three times with anhydrous ethanol and then three times with deionized water. It was then dried under vacuum at 60℃ for 24 h to obtain the amphiphilic modified biomass material.

[0089] Furthermore, according to the above proportions, weigh the amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material and put them into a high-speed mixer. Stir at 1500 r / min for 20 min at room temperature until they are evenly mixed to obtain the plugging material.

[0090] The thixotropic material is prepared by mixing hydroxyethyl cellulose, nano-silica, and modified sodium-based montmorillonite in a ratio of 5:15:80. Furthermore, the preparation method of the modified sodium-based montmorillonite is the same as in Example 1.

[0091] The anti-gas channeling material is the same as in Example 1. The micro-expansion material is the same as in Example 1. The water loss reducing agent is G310. The retarder is HX-20L. The dispersant is USZ. The defoamer is XP-1.

[0092] Example 3 This embodiment discloses a high-efficiency plugging and anti-channeling cement system for shale oil and gas development, comprising the following components by weight: 100 parts oil well cement, 32 parts heat-resistant reinforcing material, 15 parts weight-reducing material, 7 parts plugging material, 0.6 parts thixotropic material, 8 parts anti-channeling material, 1 part micro-expansion material, 3.5 parts water loss reducing agent, 1.5 parts retarder, 0.3 parts dispersant, and 0.2 parts defoamer. The cement system has a slurry liquid-to-solid ratio of 0.60 and a slurry density of 1.50 g / cm³. 3 .

[0093] The oil well cement is composed of Grade G oil well water (HSR) mixed with Grade D oil well cement (HSR) at a ratio of 8:2. The reinforcing material is the same as in Example 1.

[0094] The sealing material is prepared by uniformly mixing amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material in a ratio of 40:30:30. The amphiphilic modified flexible material is prepared by uniformly mixing modified xanthan gum, modified ultrafine asphalt powder, and modified ultrafine nitrile rubber powder in a mass ratio of 35:40:25. The amphiphilic modified rigid material is prepared by uniformly mixing modified nano-hexagonal boron nitride and modified silicon carbide whiskers in a mass ratio of 55:45. The amphiphilic modified composite biomass material is prepared by further amphiphilic modification of a composite biomass material made by mixing corn cob powder and sawdust powder in a mass ratio of 8:2.

[0095] Specifically, the preparation process of the modified xanthan gum is as follows: S1-1. Add xanthan gum and anhydrous N,N-dimethylformamide to a three-necked flask at a solid-liquid ratio of 1:20. Stir at 200 r / min in a water bath at 35°C until completely dispersed. Purge with high-purity nitrogen for 10 min to remove oxygen. Add 500 wt% ethylenediamine (by weight of xanthan gum) to the solution. Stir at 200 r / min in an ice bath at 0-3°C for 30 min. Add sodium cyanoborohydride (by weight of ethylenediamine) and heat to 35°C. React in the dark for 12 h. After the reaction, precipitate the product in excess anhydrous ethanol. Filter the product and wash three times with a mixture of anhydrous ethanol and anhydrous N,N-dimethylformamide at a volume ratio of 5:5. Dry under vacuum at 35°C for 24 h to obtain primary modified xanthan gum. S1-2. Add primary modified xanthan gum and anhydrous N,N-dimethylformamide to a Schlenk flask at a solid-liquid ratio of 1:25. Stir at 200 rpm in a 30°C water bath until completely dissolved. Add triethylamine to adjust the pH of the solution to 8.0. Transfer to an ice bath and control the temperature at 0-3°C. Add α-bromoisobutyryl bromide at a uniform rate of 2 times the mass of primary modified xanthan gum over 2 hours using a constant pressure dropping funnel. After the addition is complete, raise the temperature to 30°C and react in the dark for 8 hours. After the reaction is complete, pour the product into ice-cold anhydrous ethanol to precipitate. After filtration, wash three times with anhydrous ethanol and dry under vacuum at 35°C for 24 hours to obtain secondary modified xanthan gum. S1-3. In a Schlenk flask, add secondary modified xanthan gum, sodium 2-ethanesulfonate methacrylate, 3-(methacryloylamino)phenylboronic acid, copper bromide, tris(2-dimethylaminoethyl)amine, N,N-dimethylformamide, and deionized water in a mass ratio of 100:0.5:0.2:0.1:0.1:1.0:100. Stir at 200 rpm for 30 min at room temperature, purge with nitrogen for 20 min, seal, and react under a blue light source at room temperature for 5 h. Then add to the solution in a mass ratio of... Isobornyl methacrylate, adamantyl methacrylate, and vinyltriethoxysilane (total mass of the three is 400 wt% of the total mass of sodium 2-ethanesulfonate methacrylate and 3-(methacryloylamino)phenylboronic acid) were added in a 7:2:1 ratio. After purging with nitrogen for 10 min, the mixture was sealed and reacted at room temperature under a blue light source for 5 h. After the reaction was completed, the product was poured into a 1:1 volume ratio of ice-anhydrous ethanol-acetone mixture to precipitate. After filtration, the product was washed three times with anhydrous ethanol and dried under vacuum at 35 °C for 24 h to obtain modified xanthan gum.

[0096] Specifically, the modified asphalt powder is prepared through the following steps: S2-1. Take 90# asphalt and vacuum dry it at 120℃ for 4 hours. After pulverizing it with a universal pulverizer, sieve it through a 300-mesh standard sieve to obtain ultrafine asphalt powder with D50≤50μm. Take 20 parts by weight of anhydrous ethanol, add 0.2 parts by weight of glacial acetic acid to adjust the pH to 5.0, and then add 3.5 parts by weight of KH550 silane coupling agent. Stir evenly at room temperature to obtain a buffer solution. S2-2. Take 10 parts by weight of organomontmorillonite powder and put it into a mixer. Heat the mixture to 80°C and rotate at 1500 r / min. Add 6 vol% of the above-mentioned ethanol buffer solution dropwise. Disperse at high speed for 1 hour and then pour out the mixture to obtain modified organomontmorillonite. Take 100 parts by weight of ultrafine asphalt powder and put it into a mixer. Rotate the mixture at 500 r / min and add the remaining 94 vol% of the above-mentioned ethanol buffer solution dropwise at room temperature for 20 minutes. After the dropwise addition is completed, heat the mixture to 65°C and adjust the rotation speed to 1000 r / min. Stir and react for 1 hour and then pour out the mixture. Vacuum dry at 60°C for 3 hours to obtain primary modified ultrafine asphalt powder. S2-3. In a mixer, add 100 parts by weight of primary modified ultrafine asphalt powder and 5.5 parts by weight of modified organomontmorillonite in sequence, and mix at 1000 r / min for 5 min. Increase the speed to 2000 r / min, add 7.0 parts by weight of octadecyl methacrylate, 4.5 parts by weight of hydroxyethyl methacrylate, 0.4 parts by weight of azobisisobutyronitrile, and 0.3 parts by weight of antioxidant 1076, and add for 15 min. Disperse at room temperature and speed for 30 min to obtain secondary modified ultrafine asphalt powder. S2-4. Transfer 100 parts by mass of the secondary modified ultrafine asphalt powder into a reactor. After purging the reactor with high-purity CO2 for 10 minutes to replace the air inside, seal the reactor. Increase the temperature to 120°C at 2°C / min and simultaneously increase the pressure to 20MPa to make the CO2 reach a supercritical state. Stir the reaction at 300r / min for 3 hours. Stop heating and stirring, slowly release the pressure inside the reactor, and vacuum dry the reactants at 140°C for 2 hours to remove unreacted residues. After pulverizing, sieve the powder through a 500-mesh standard sieve to obtain powder with D50≤25μm. Pour the powder into a mixer, add 0.6 parts by mass of fumed silica, stir at 1500r / min at room temperature for 10 minutes, and then pour out the mixture to obtain the modified ultrafine asphalt powder.

[0097] Specifically, the modified nitrile rubber is prepared through the following steps: S3-1. Take 40 parts by weight of anhydrous ethanol, add glacial acetic acid to adjust the pH to 4.0, then add 4.0 parts by weight of KH570 silane coupling agent, stir at room temperature for 30 minutes to obtain a buffer solution; prepare three groups of solutions A, B, and C: Solution A is prepared by stirring 43 parts by weight of bisphenol A type epoxy resin, 33 parts by weight of cashew nut shell liquid modified phenolic resin, and 18 parts by weight of butyl acrylate at room temperature until homogeneous; Solution B is prepared by stirring 17 parts by weight of methacrylic acid and 2 parts by weight of butyl acrylate at room temperature until homogeneous; Solution C is prepared by dissolving 1.2 parts by weight of potassium persulfate in 10 parts by weight of deionized water at room temperature until homogeneous. S3-2. Take 100 parts by weight of 200 mesh ultrafine nitrile rubber powder and add it to a high-speed dispersion vessel. Add the above buffer solution dropwise at a speed of 1500 r / min for 20 min. After the addition is completed, heat to 60℃ and stir for 1.5 h. Wash the product three times with anhydrous ethanol and dry it under vacuum at 60℃ for 24 h to obtain primary modified ultrafine nitrile rubber powder. S3-3. Take 100 parts by weight of primary modified ultrafine nitrile rubber powder and add it to the reactor. Then add 250 parts by weight of deionized water, 3.0 parts by weight of sodium dodecylbenzenesulfonate, 1.5 parts by weight of octylphenol polyoxyethylene ether, and 1.0 part by weight of sodium polyacrylate in sequence. Stir at 300 r / min for 10 min at room temperature, and then stir at 5000 r / min for 30 min. Purge the reactor with high-purity nitrogen to replace the air for 10 min. Raise the temperature to 80°C and reduce the stirring speed to 500 r / min. First, add solution A dropwise at a uniform rate, and then add solution C at 70% of the volume ratio. The dropwise addition time is 1 h. After the dropwise addition is completed, keep the reaction temperature at 2 h. Then add solution B and the remaining 30% of solution C dropwise. The dropwise addition time is 0.5 h. After the dropwise addition is completed, keep the reaction temperature at 3 h. S3-4. Reduce the temperature of the reactor to 40℃, add 5.5 parts by weight of dicyandiamide, 0.4 parts by weight of 2-ethyl-4-methylimidazole, and 0.5 parts by weight of antioxidant 1010. Adjust the speed to 3000 r / min and disperse at high speed for 20 min to obtain a uniform emulsion. Send the emulsion into a centrifugal spray dryer, set the inlet air temperature to 130℃, the outlet air temperature to 60℃, and the atomizing disc speed to 25000 r / min, and spray dry continuously to obtain modified ultrafine nitrile rubber powder.

[0098] Specifically, the modified nano-hexagonal boron nitride is prepared by the following method: S4-1. Place nano-hexagonal boron nitride powder in the cavity of a low-temperature plasma treatment instrument and treat it for 20 min at 35℃, power 100W, oxygen flow rate 20sccm, and vacuum degree 10Pa. Then, place the treated powder into a muffle furnace and calcine it to 550℃ at 5℃ / min in an air atmosphere for 5 h. S4-2. In a three-necked flask, calcined nano-hexagonal boron nitride powder was added to anhydrous ethanol at a solid-liquid ratio of 1:90. Nitrogen gas was introduced to remove oxygen for 10 min, and the mixture was ultrasonically dispersed for 20 min under stirring at 300 r / min. Anhydrous acetic acid was added to adjust the pH to 5.0. The mixture was then transferred to a 60℃ water bath, and 30 wt% KH550 silane coupling agent of nano-hexagonal boron nitride was added. The mixture was stirred and kept at the temperature for 2 h. 15 wt% 1H,1H,2H,2H-perfluorodecyltriethoxysilane of nano-hexagonal boron nitride was added dropwise over 1 h using a constant pressure dropping funnel. After the addition was completed, the mixture was stirred and reacted for 5 h. S4-3. After filtering the reaction product, it was washed three times by centrifugation with anhydrous ethanol and dried under vacuum at 60°C for 24 hours to obtain modified nano-hexagonal boron nitride.

[0099] Specifically, the modified silicon carbide whiskers are prepared by the following method: S5-1. Take β-silicon carbide whiskers with a diameter of 0.1~0.5μm and a length of 5~20μm and place them in a muffle furnace. Heat the furnace to 800℃ at 10℃ / min and calcine in air atmosphere for 3h to obtain primary modified silicon carbide whiskers. S5-2. At room temperature, primary modified silicon carbide whiskers and anhydrous ethanol were added to a three-necked flask at a solid-liquid ratio of 1:60. Nitrogen gas was introduced to remove oxygen for 10 min, and the mixture was ultrasonically dispersed at 300 r / min for 20 min. Anhydrous acetic acid was added to adjust the pH to 5.0. The mixture was then transferred to a 60℃ water bath, and 35 wt% of KH560 silane coupling agent (by weight of the whiskers) was added. The mixture was stirred and kept at this temperature for 4 h. The product was washed three times by centrifugation with anhydrous ethanol and dried under vacuum at 60℃ for 24 h to obtain secondary modified silicon carbide whiskers. S5-3. At room temperature, secondary modified silicon carbide whiskers and N,N-dimethylformamide were added to a three-necked flask at a solid-liquid ratio of 1:45. Nitrogen gas was introduced to remove oxygen for 10 min, and the mixture was ultrasonically dispersed for 20 min under stirring at 300 r / min. Then, 30 wt% p-aminobenzenesulfonic acid and 30 wt% triethylamine were added. The mixture was transferred to a 90°C water bath and stirred and kept at the temperature for 8 h. The product was washed three times with deionized water and dried under vacuum at 80°C for 48 h to obtain modified silicon carbide whiskers.

[0100] Specifically, the preparation process of the amphiphilic modified biomass material is as follows: S6-1. Take corn cobs and sawdust, rinse and filter them three times with tap water, dry them in a 60℃ forced-air drying oven for 24 hours, pulverize them with a high-speed universal pulverizer, and then sieve them through a 200-mesh standard sieve to obtain corn cob powder and sawdust powder. S6-2. Mix corn cob powder and sawdust powder evenly at a mass ratio of 8:2, add 55wt% petroleum ether of the total mass of the composite powder, and extract by Soxhlet extraction for 5 hours to remove oil and wax; after vacuum filtration, add 55wt% 85% ethanol solution of the total mass of the composite powder and continue extraction for 3 hours to remove soluble components; wash the product twice with anhydrous ethanol and vacuum dry at 60℃ for 24 hours to obtain purified composite biomass powder; S6-3. Add purified composite biomass powder and alkaline alcohol solution (10% NaOH solution and anhydrous ethanol at a volume ratio of 4:6) to a three-necked flask at a solid-liquid ratio of 1:33. Purge the flask with nitrogen gas for 10 min to remove oxygen, then seal it. Stir the mixture at 200 r / min for 8 h at room temperature, then raise the temperature to 60 °C and stir for another 3 h. Wash the product three times with deionized water and dry it under vacuum at 60 °C for 24 h to obtain activated composite biomass powder. S6-4. In a three-necked flask, add activated composite biomass powder, phenol, glycidyl methacrylate, styrene, and N-hydroxymethylacrylamide in a mass ratio of 100:30:35:12:4, and add deionized water to prepare a solution with a solid content of 25%. Add 1.0 wt% of ammonium persulfate and 2.0 wt% of sodium carbonate, and stir evenly at room temperature. S6-5. Nitrogen gas was introduced into the bottle to remove oxygen for 10 min. The temperature was raised to 50℃ and stirred at 300 r / min for 2 h. The temperature was then raised to 85℃ and stirred for another 3 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed three times with anhydrous ethanol and then three times with deionized water. It was then dried under vacuum at 60℃ for 24 h to obtain the amphiphilic modified biomass material.

[0101] Furthermore, according to the above proportions, weigh the amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material and put them into a high-speed mixer. Stir at 1500 r / min for 20 min at room temperature until they are evenly mixed to obtain the plugging material.

[0102] The thixotropic material is prepared by mixing hydroxyethyl cellulose, nano-silica, and modified sodium-based montmorillonite in a ratio of 10:20:70. Furthermore, the preparation method of the modified sodium-based montmorillonite is the same as in Example 1.

[0103] The anti-gas channeling material is the same as in Example 1. The micro-expansion material is the same as in Example 1. The water loss reducing agent is BS108. The retarder is BS200L. The dispersant is USZ. The defoamer is BP-1A.

[0104] Example 4 This embodiment discloses a high-efficiency plugging and anti-channeling cement system for shale oil and gas development, comprising the following components by weight: 100 parts oil well cement, 35 parts heat-resistant reinforcing material, 7 parts weight-reducing material, 12 parts plugging material, 0.4 parts thixotropic material, 4 parts anti-channeling material, 2 parts micro-expansion material, 2 parts water loss reducing agent, 2.5 parts retarder, 0.2 parts dispersant, and 0.2 parts defoamer. The cement system has a slurry liquid-to-solid ratio of 0.48 and a slurry density of 1.73 g / cm³. 3 .

[0105] The oil well cement is the same as in Example 3. The reinforcing material is the same as in Example 1.

[0106] The sealing material is prepared by uniformly mixing amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material in a ratio of 40:27.5:32.5. Further, the amphiphilic modified flexible material is prepared by uniformly mixing modified xanthan gum, modified ultrafine asphalt powder, and modified ultrafine nitrile rubber powder in a mass ratio of 35:35:30; the amphiphilic modified rigid material is prepared by uniformly mixing modified nano-hexagonal boron nitride and modified silicon carbide whiskers in a mass ratio of 50:50; and the amphiphilic modified composite biomass material is prepared by further amphiphilic modification of a composite biomass material obtained by mixing corn cob powder and sawdust powder in a mass ratio of 7.5:2.5.

[0107] In this embodiment, the preparation steps of modified xanthan gum, modified ultrafine asphalt powder, modified ultrafine nitrile rubber powder, modified nano-hexagonal boron nitride, and modified silicon carbide whiskers are completely consistent with those in Example 1, with only the preparation parameters of the amphiphilic modified biomass material and the final formulation of the plugging material being adjusted.

[0108] Specifically, the preparation process of the amphiphilic modified biomass material is as follows: S6-1. Take corn cobs and sawdust, rinse and filter them three times with tap water, dry them in a 60℃ forced-air drying oven for 24 hours, pulverize them with a high-speed universal pulverizer, and then sieve them through a 200-mesh standard sieve to obtain corn cob powder and sawdust powder. S6-2. Mix corn cob powder and sawdust powder evenly at a mass ratio of 7.5:2.5, add 52wt% petroleum ether of the total mass of the composite powder, and extract by Soxhlet extraction for 5 hours to remove oil and wax; after vacuum filtration, add 52wt% 85% ethanol solution of the total mass of the composite powder and continue extraction for 3 hours to remove soluble components; wash the product twice with anhydrous ethanol and vacuum dry at 60℃ for 24 hours to obtain purified composite biomass powder; S6-3. Add purified composite biomass powder and alkaline alcohol solution (10% NaOH solution and anhydrous ethanol at a volume ratio of 3.5:6.5) to a three-necked flask at a solid-liquid ratio of 1:30. Purge the flask with nitrogen gas for 10 min to remove oxygen, then seal it. Stir the mixture at 200 r / min for 7 h at room temperature, then raise the temperature to 60 °C and stir for another 2 h. Wash the product three times with deionized water and dry it under vacuum at 60 °C for 24 h to obtain activated composite biomass powder. S6-4. In a three-necked flask, add activated composite biomass powder, phenol, glycidyl methacrylate, styrene, and N-hydroxymethylacrylamide in a mass ratio of 100:26:31:9:2.5, and add deionized water to prepare a solution with a solid content of 22%. Add 0.85 wt% ammonium persulfate and 1.6 wt% sodium carbonate, and stir evenly at room temperature. S6-5. Nitrogen gas was introduced into the bottle to remove oxygen for 10 min. The temperature was raised to 50℃ and stirred at 300 r / min for 1 h. The temperature was then raised to 85℃ and stirred for another 2.5 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed three times with anhydrous ethanol and then three times with deionized water. It was then dried under vacuum at 60℃ for 24 h to obtain the amphiphilic modified biomass material.

[0109] Furthermore, according to the above proportions, weigh the amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material and put them into a high-speed mixer. Stir at 1500 r / min for 20 min at room temperature until they are evenly mixed to obtain the plugging material.

[0110] The thixotropic material is prepared by mixing hydroxyethyl cellulose, nano-silica, and modified sodium-based montmorillonite in a ratio of 5:25:70. Furthermore, the preparation method of the modified sodium-based montmorillonite is the same as in Example 1.

[0111] The anti-gas channeling material is the same as in Example 1. The micro-expansion material is the same as in Example 1. The water loss reducing agent is G33S. The retarder is T613. The dispersant is USZ. The defoamer is BP-1A.

[0112] Example 5 This embodiment discloses a high-efficiency plugging and anti-channeling cement system for shale oil and gas development, comprising the following components by weight: 100 parts oil well cement, 33 parts heat-resistant reinforcing material, 10 parts weight-reducing material, 11 parts plugging material, 0.3 parts thixotropic material, 5 parts anti-channeling material, 3 parts micro-expansion material, 2.5 parts water loss reducing agent, 2.3 parts retarder, 0.5 parts dispersant, and 0.2 parts defoamer. The cement system has a slurry liquid-to-solid ratio of 0.52 and a slurry density of 1.82 g / cm³. 3 .

[0113] The oil well cement is the same as in Example 3. The reinforcing material is the same as in Example 1.

[0114] The plugging material is prepared by uniformly mixing amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material in a ratio of 38:28:34. Further, the amphiphilic modified flexible material is prepared by uniformly mixing modified xanthan gum, modified ultrafine asphalt powder, and modified ultrafine nitrile rubber powder in a mass ratio of 34:38:28; the amphiphilic modified rigid material is prepared by uniformly mixing modified nano-hexagonal boron nitride and modified silicon carbide whiskers in a mass ratio of 54:46; and the amphiphilic modified composite biomass material is prepared by further amphiphilic modification of a composite biomass material obtained by mixing corn cob powder and sawdust powder in a mass ratio of 6.5:3.5.

[0115] In this embodiment, the preparation steps of modified xanthan gum, modified ultrafine asphalt powder, modified ultrafine nitrile rubber powder, modified nano-hexagonal boron nitride, and modified silicon carbide whiskers are completely consistent with those in Example 1, with only the preparation parameters of the amphiphilic modified biomass material and the final formulation of the plugging material being adjusted.

[0116] Specifically, the preparation process of the amphiphilic modified biomass material is as follows: S6-1. Take corn cobs and sawdust, rinse and filter them three times with tap water, dry them in a 60℃ forced-air drying oven for 24 hours, pulverize them with a high-speed universal pulverizer, and then sieve them through a 200-mesh standard sieve to obtain corn cob powder and sawdust powder. S6-2. Mix corn cob powder and sawdust powder evenly at a mass ratio of 6.5:3.5, add 54 wt% petroleum ether of the total mass of the composite powder, and extract by Soxhlet extraction for 5 h to remove oil and wax; after vacuum filtration, add 54 wt% 85% ethanol solution of the total mass of the composite powder and continue extraction for 3 h to remove soluble components; wash the product twice with anhydrous ethanol and vacuum dry at 60℃ for 24 h to obtain purified composite biomass powder; S6-3. Add purified composite biomass powder and alkaline alcohol solution (10% NaOH solution and anhydrous ethanol at a volume ratio of 3.8:6.2) to a three-necked flask at a solid-liquid ratio of 1:32. Purge the flask with nitrogen gas for 10 min to remove oxygen, then seal it. Stir the mixture at 200 r / min for 7.5 h at room temperature, then raise the temperature to 60 °C and stir for another 2.5 h. Wash the product three times with deionized water and dry it under vacuum at 60 °C for 24 h to obtain activated composite biomass powder. S6-4. In a three-necked flask, add activated composite biomass powder, phenol, glycidyl methacrylate, styrene, and N-hydroxymethylacrylamide in a mass ratio of 100:29:34:11:3.5, and add deionized water to prepare a solution with a solid content of 24%. Add 0.95 wt% ammonium persulfate and 1.9 wt% sodium carbonate, and stir evenly at room temperature. S6-5. Nitrogen gas was introduced into the bottle to remove oxygen for 10 min. The temperature was raised to 50℃ and the mixture was stirred at 300 r / min for 1.5 h. The temperature was then raised to 85℃ and the mixture was stirred for another 3 h. After the reaction was completed, the mixture was cooled to room temperature. The product was washed three times with anhydrous ethanol and then three times with deionized water. It was then dried under vacuum at 60℃ for 24 h to obtain the amphiphilic modified biomass material.

[0117] Furthermore, according to the above proportions, weigh the amphiphilic modified flexible material, amphiphilic modified rigid material, and amphiphilic modified biomass material and put them into a high-speed mixer. Stir at 1500 r / min for 20 min at room temperature until they are evenly mixed to obtain the plugging material.

[0118] The thixotropic material is prepared by mixing hydroxyethyl cellulose, nano-silica, and modified sodium-based montmorillonite in a ratio of 8:17:75. Furthermore, the preparation method of the modified sodium-based montmorillonite is the same as in Example 1.

[0119] The anti-gas channeling material is the same as in Example 1. The micro-expansion material is the same as in Example 1. The water loss reducing agent is T816. The retarder is GH-9. The dispersant is USZ. The defoamer is XP-1.

[0120] Comparative Example 1 This comparative example uses a conventional high-temperature cementing system for plugging lost circulation, composed of the following components by weight: 100 parts of Grade G well cement (HSR), 33 parts of quartz sand, 15 parts of plugging material (fiber-based), 2.5 parts of fluid loss reducer (G33S), 2.5 parts of retarder (GH-9), 0.3 parts of dispersant (USZ), and 0.2 parts of defoamer (XP-1). The system has a liquid-to-solid ratio of 0.42 and a slurry density of 1.90 g / cm³. 3 .

[0121] Comparative Example 2 This comparative example uses a conventional high-temperature cementing system for plugging lost circulation, composed of the following components by weight: 100 parts of Grade G oil well cement (HSR), 34 parts of quartz sand, 10 parts of plugging material (mica powder), 5 parts of plugging material (cottonseed hulls), 2 parts of fluid loss reducer (G310), 2.5 parts of retarder (BS200L), 0.3 parts of dispersant (USZ), and 0.2 parts of defoamer (BP-1A). The system has a liquid-to-solid ratio of 0.55 and a slurry density of 1.65 g / cm³. 3 .

[0122] Performance comparison test: The high-efficiency plugging and anti-channeling cement system for shale oil and gas development obtained in Examples 1-5 above and the conventional high-temperature cementing plugging system prepared in Comparative Examples 1-2 were tested and analyzed in accordance with GB / T 19139 "Test Methods for Oil Well Cement" and SY / T 5840 "Indoor Test Methods for Bridging and Plugging Materials for Drilling Fluids". The experimental results are shown in the table below:

[0123] As shown in the experimental results in the table above, the cement system for plugging and preventing leakage in the embodiment of the present invention exhibits good slurry stability with a density difference of 0 between the upper and lower layers. The slurry also demonstrates good thixotropic properties, with a final shear force of over 15 Pa after 10 minutes. This plays a crucial role in suspending the plugging material and resisting the scouring capacity of formation fluids. Furthermore, the cement stone exhibits good mechanical properties, displaying a high strength and low elastic modulus. The gas channeling coefficient is less than 0.3, and the pressure resistance of 5 mm cracks and pores is greater than 10 MPa. All experimental data indicate that its plugging performance and mechanical properties are significantly superior to those of the comparative example, demonstrating the superiority of the technical solution of the present invention.

[0124] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications made by those skilled in the art without departing from the concept and principles of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development, characterized in that: This cement system, by weight, comprises the following components: 100 parts oil well cement, 28-35 parts heat-resistant reinforcing material, 0-15 parts weight-reducing material, 7-15 parts plugging material, 0.2-0.6 parts thixotropic material, 4-8 parts gas channeling prevention material, 1-3 parts micro-expansion material, 2-3.5 parts fluid loss reducing agent, 1.5-2.5 parts retarder, 0.2-0.5 parts dispersant, and 0.2 parts defoamer; The plugging material is prepared by uniformly mixing amphiphilic modified flexible material, amphiphilic modified rigid material and amphiphilic modified biomass material in a mass ratio of (35~40):(25~30):(30~35); The amphiphilic modified flexible material is formed by uniformly mixing and compounding modified xanthan gum, modified bitumen powder and modified nitrile rubber powder in a mass ratio of (30~35):(35~40):(25~30); The amphiphilic modified rigid material is made by mixing modified nano-hexagonal boron nitride and modified silicon carbide whiskers in a mass ratio of (50~55):(45~50); The amphiphilic modified composite biomass material is prepared by mixing corn cob powder and sawdust powder in a mass ratio of (6~8):(2~4) and then modifying it with amphiphilic material. The thixotropic material is prepared by mixing hydroxyethyl cellulose, nano-silica and modified sodium-based montmorillonite in a mass ratio of (5~10):(15~25):(70~80); The liquid-to-solid ratio of this cement system is 0.44~0.

60. By adjusting and reducing the amount of material admixtures and the liquid-to-solid ratio, the paste density of the cement system is made to be 1.50 g / cm³. 3 ~1.90g / cm 3 Regulation within a specified range.

2. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 1, characterized in that: The modified xanthan gum was prepared by the following method: S1-1. Xanthan gum is dispersed in anhydrous N,N-dimethylformamide. After oxygen is removed by nitrogen, ethylenediamine is added and stirred under ice bath conditions. Then sodium cyanoborohydride is added and heated to react. After post-treatment, primary modified xanthan gum is obtained. S1-2. Primary modified xanthan gum is dispersed in anhydrous N,N-dimethylformamide, triethylamine is added to adjust the pH, and α-bromoisobutyryl bromide is added dropwise under low temperature conditions to carry out the acylation reaction. After post-treatment, secondary modified xanthan gum is obtained. S1-3. Using secondary modified xanthan gum as a substrate, sodium 2-ethanesulfonate methacrylate, 3-(methacrylamido)phenylboronic acid, copper bromide, tris(2-dimethylaminoethyl)amine, N,N-dimethylformamide, and deionized water were first added. After stirring, removing oxygen, and sealing, the first stage of polymerization was initiated by blue light. Then, isobornyl methacrylate, adamantyl methacrylate, and vinyltriethoxysilane were added to the system. After removing oxygen and sealing, the second stage of polymerization was initiated by blue light. After post-treatment, modified xanthan gum was obtained.

3. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 2, characterized in that: In step S1-1, the solid-liquid ratio of xanthan gum to anhydrous N,N-dimethylformamide is 1:(15~20); 500wt% of ethylenediamine is added, and the mixture is stirred for 30min in an ice bath at 0~3℃ and 200r / min; then sodium cyanoborohydride of equal mass to ethylenediamine is added, and the mixture is heated to 35℃ and reacted in the dark for 12h; after the reaction is completed, the mixture is precipitated with anhydrous ethanol, filtered, and then washed with a mixture of anhydrous ethanol and anhydrous N,N-methylformamide at a volume ratio of 5:5, and dried under vacuum at 35℃ for 24h.

4. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 2, characterized in that: In steps S1-2, the solid-liquid ratio of primary modified xanthan gum to anhydrous N,N-dimethylformamide is 1:(20~25); triethylamine is added to adjust the pH to 8.0; α-bromoisobutyryl bromide of 2 times the mass of primary modified xanthan gum is added dropwise at a uniform rate over 2 hours under an ice bath at 0~3℃; after the addition is complete, the temperature is raised to 30℃ and the reaction is carried out in the dark for 8 hours; the reaction product is precipitated with ice-cold anhydrous ethanol, washed, and dried under vacuum at 35℃ for 24 hours.

5. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 2, characterized in that: In steps S1-3, secondary modified xanthan gum, sodium 2-ethanesulfonate methacrylate, 3-(methacrylamido)phenylboronic acid, copper bromide, tris(2-dimethylaminoethyl)amine, N,N-dimethylformamide, and deionized water are added sequentially in a mass ratio of 100:(0.3~0.5):(0.1~0.2):(0.05~0.1):(0.05~1.0):

100. The mixture is stirred uniformly at 200 rpm for 30 min at room temperature, then nitrogen gas is introduced to purge oxygen for 20 min before sealing. The mixture was placed under a blue light source and reacted at room temperature for 5 hours. Then, isobornyl methacrylate, adamantyl methacrylate, and vinyltriethoxysilane were added at a mass ratio of 7:2:1, with the total mass of the three being 350-400 wt% of the total mass of sodium 2-ethanesulfonate methacrylate and 3-(methacrylamido)phenylboronic acid. After purging with nitrogen for 10 minutes to remove oxygen, the mixture was sealed and reacted at room temperature under a blue light source for 5 hours. The product was then poured into a 1:1 mixture of ice-anhydrous ethanol and acetone to precipitate, filtered, washed with anhydrous ethanol, and dried under vacuum at 35°C for 24 hours.

6. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 1, characterized in that: The modified asphalt powder is prepared through the following steps: S2-1. Dry, pulverize, and sieve the asphalt to obtain ultrafine asphalt powder with D50≤50μm; prepare an ethanol buffer solution containing KH550 silane coupling agent. S2-2. The organomontmorillonite and the ultrafine asphalt powder are modified using the ethanol buffer solution to obtain modified organomontmorillonite and primary modified asphalt powder. S2-3. Mix the primary modified asphalt powder with modified organic montmorillonite, add octadecyl methacrylate, hydroxyethyl methacrylate, azobisisobutyronitrile and antioxidant 1076, and disperse at high speed at room temperature to obtain secondary modified ultrafine asphalt powder. S2-4. The modified asphalt powder is reacted under supercritical CO2, dried, pulverized, sieved, and then blended with fumed silica to obtain the modified asphalt powder.

7. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 6, characterized in that: In step S2-1, take 20 parts by mass of anhydrous ethanol, add 0.2 parts by mass of glacial acetic acid, adjust the pH to 5.0, then add 2.5~3.5 parts by mass of KH550 silane coupling agent, stir evenly at room temperature to obtain ethanol buffer solution.

8. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 7, characterized in that: In step S2-2, 10 parts by mass of organomontmorillonite are placed in a mixer, heated to 80°C and the rotation speed is adjusted to 1500 r / min. 4 vol%~6 vol% of the ethanol buffer prepared in step S2-1 is added dropwise, and after high-speed dispersion for 1 h, modified organomontmorillonite is obtained.

9. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 8, characterized in that: In step S2-2, 100 parts by weight of ultrafine asphalt powder are placed in a mixer, the speed is adjusted to 500 r / min, and the remaining ethanol buffer solution is added dropwise at a uniform rate at room temperature for 20 min. After the addition is completed, the temperature is raised to 65℃, the speed is increased to 1000 r / min, and the mixture is stirred and reacted for 1 h. The mixture is then poured out and vacuum dried at 60℃ for 3 h to obtain primary modified ultrafine asphalt powder.

10. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 6, characterized in that: In step S2-3, 100 parts by weight of primary modified ultrafine asphalt powder and 4.5-5.5 parts by weight of modified organomontmorillonite are added sequentially to the mixer and stirred at 1000 r / min. Then, the speed is increased to 200 r / min, and 6.5-7.0 parts by weight of octadecyl methacrylate, 4.0-4.5 parts by weight of hydroxyethyl methacrylate, 0.3-0.4 parts by weight of azobisisobutyronitrile, and 0.2-0.3 parts by weight of antioxidant 1076 are added and dispersed at high speed at room temperature to obtain secondary modified ultrafine asphalt powder.

11. The high-efficiency plugging and anti-channeling cement system for shale oil and gas development as described in claim 6, characterized in that: In step S2-4, 100 parts by mass of the secondary modified ultrafine asphalt powder are transferred to a reactor. After the air inside the reactor is replaced by high-purity CO2, the reactor is sealed. The temperature is increased to 120°C at 2°C / min, and the pressure is increased to 20MPa simultaneously to make the CO2 reach a supercritical state. The stirring speed is adjusted to 300r / min and the reaction is carried out for 3 hours. Then, heating and stirring are stopped and the pressure inside the reactor is released. The reactants are vacuum dried at 140°C to remove unreacted residues. The reactants are then pulverized and sieved to obtain powder with D50≤20μm. The powder is then poured into a mixer, and 0.4~0.6 parts by mass of fumed silica are added. The mixture is stirred at 1500r / min at room temperature to obtain the modified asphalt powder.

12. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 6-11, characterized in that: The asphalt is any one of 50#, 70# and 90# asphalt.

13. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 1, characterized in that: The modified nitrile rubber is prepared through the following steps: S3-1. Prepare an ethanol buffer solution containing KH570 silane coupling agent; prepare an epoxy resin solution containing bisphenol A type epoxy resin, cashew nut shell liquid modified phenolic resin and butyl acrylate; prepare an acrylate solution containing methacrylic acid and butyl acrylate; prepare an initiator solution containing potassium persulfate and deionized water. S3-2. Use an ethanol buffer containing KH570 silane coupling agent to perform coupling modification on ultrafine nitrile rubber powder to obtain primary modified ultrafine nitrile rubber powder. S3-3. Disperse the primary modified ultrafine nitrile rubber powder, add sodium dodecylbenzene sulfonate, octylphenol polyoxyethylene ether and sodium polyacrylate, heat to 80°C in a nitrogen atmosphere, and add epoxy resin liquid and 70% volume ratio of initiator liquid dropwise in sequence; then add acrylate liquid and the remaining initiator liquid dropwise to react. S3-4. After cooling to 40°C, dicyandiamide, 2-ethyl-4-methylimidazole and antioxidant 1010 are added and dispersed at high speed to form a uniformly dispersed emulsion. The emulsion is then spray-dried to obtain the modified nitrile rubber.

14. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 13, characterized in that: In step S3-1, take 35-40 parts by weight of anhydrous ethanol, add glacial acetic acid to adjust the pH to 4.0, add 3.0-4.0 parts by weight of KH570 silane coupling agent, and stir at room temperature to obtain the ethanol buffer solution.

15. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 14, characterized in that: In step S3-1, 40-43 parts by weight of bisphenol A type epoxy resin, 30-33 parts by weight of cashew nut shell liquid modified phenolic resin and 15-18 parts by weight of butyl acrylate are used and stirred evenly at room temperature to obtain epoxy resin liquid.

16. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 14, characterized in that: In step S3-1, 14-17 parts by mass of methacrylic acid and 1-2 parts by mass of butyl acrylate are mixed evenly at room temperature to obtain an acrylate solution.

17. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 14, characterized in that: In step S3-1, 1.0 to 1.2 parts by mass of potassium persulfate are added to 10 parts by mass of deionized water, and the mixture is stirred evenly at room temperature to obtain the initiator solution.

18. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 13-17, characterized in that: In step S3-2, 100 parts by mass of ultrafine nitrile rubber were added to a dispersion vessel, and the ethanol buffer solution prepared in step S3-1 was added dropwise at a speed of 1500 r / min for 20 min. After the addition was completed, the temperature was raised to 60℃ and the mixture was stirred for 1.5 h. After the reaction was completed, the product was washed with anhydrous ethanol to remove unreacted coupling agent and other impurities. The product was then vacuum dried at 60℃ for 24 h to obtain primary modified ultrafine nitrile rubber powder.

19. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 13-17, characterized in that: In step S3-3, 100 parts by weight of primary modified ultrafine nitrile rubber powder are added to the reactor. Then, 250 parts by weight of deionized water, 2.5-3.0 parts by weight of sodium dodecylbenzenesulfonate, 1.0-1.5 parts by weight of octylphenol polyoxyethylene ether, and 0.5-1.0 parts by weight of sodium polyacrylate are added sequentially. The mixture is stirred at 300 r / min for 10 min at room temperature, and then stirred at 5000 r / min for 30 min. Nitrogen gas is introduced into the reactor to replace the air inside. The reactor is heated to 80°C and the stirring speed is reduced to 500 r / min. The epoxy resin solution prepared in step S3-1 and 70% of the initiator solution are added dropwise at a uniform rate for 1 h. After the addition is completed, the reaction is kept at the temperature for 2 h. Then, the acrylate solution and the remaining 30% of the initiator solution are added dropwise at a uniform rate for 0.5 h. After the addition is completed, the reaction is kept at the temperature for 3 h.

20. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 19, characterized in that: In step S3-4, the reaction vessel is cooled to 40°C, and then 5.0~5.5 parts by weight of dicyandiamide, 0.2~0.4 parts by weight of 2-ethyl-4-methylimidazole, and 0.3~0.5 parts by weight of antioxidant 1010 are added. The rotation speed is adjusted to 3000 r / min, and the mixture is dispersed at high speed for 20 min to form a uniformly dispersed emulsion. The emulsion is fed into a centrifugal spray dryer, with the inlet air temperature set at 130℃, the outlet air temperature at 60℃, and the atomizing disc speed at 25000 r / min, for continuous spray drying to obtain the modified nitrile rubber powder.

21. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 13-17, characterized in that: The ultrafine nitrile rubber powder in step S3-2 has a mesh size ≥200 mesh.

22. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 1, characterized in that: The modified nano-hexagonal boron nitride was prepared by the following method: S4-1. Nano-hexagonal boron nitride powder is subjected to plasma treatment followed by calcination; S4-2. Add the calcined nano-hexagonal boron nitride to anhydrous ethanol, add anhydrous acetic acid to adjust the pH, and modify it sequentially with KH550 silane coupling agent and 1H,1H,2H,2H-perfluorodecyltriethoxysilane. S4-3. The reactants obtained in step S4-2 are washed and dried to obtain the modified nano-hexagonal boron nitride.

23. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 22, characterized in that: In step S4-1, the plasma treatment conditions are as follows: treatment time 15~20 min, temperature 35℃, power 100 W, oxygen flow rate 20 sccm, vacuum degree 10 Pa; calcination temperature 500~550℃, calcination time 5 h.

24. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 22, characterized in that: In step 4-2, the solid-liquid ratio of the calcined nano-hexagonal boron nitride powder to anhydrous ethanol is 1:(80~90); anhydrous acetic acid is added to adjust the pH to 5.0; in a 60℃ water bath, 25~30wt% of calcined nano-hexagonal boron nitride KH550 silane coupling agent is added, and the reaction is kept at this temperature for 2 hours. Then, 10~15wt% of calcined nano-hexagonal boron nitride 1H,1H,2H,2H-perfluorodecyltriethoxysilane is added dropwise at a constant pressure dropping funnel over 1 hour. After the addition is complete, the reaction is stirred for 5 hours.

25. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 1, characterized in that: The modified silicon carbide whiskers were prepared by the following method: S5-1. Take β-silicon carbide whiskers, heat them to 750~800℃ at 10℃ / min, and calcine them in air atmosphere for 2~3h to obtain primary modified silicon carbide whiskers. S5-2. Under room temperature conditions, the primary modified silicon carbide whiskers were dispersed in anhydrous ethanol at a solid-liquid ratio of 1:(50~60). Nitrogen gas was introduced to remove oxygen, and the mixture was ultrasonically dispersed for 20 min with stirring at 300 r / min. Anhydrous acetic acid was added to adjust the pH to 5.

0. The mixture was then transferred to a 60℃ water bath, and 30~35 wt% of KH560 silane coupling agent (by weight of the primary modified silicon carbide whiskers) was added. The mixture was stirred and kept at the temperature for 4 h. After the reaction was completed, the mixture was washed with anhydrous ethanol and then vacuum dried to obtain secondary modified silicon carbide whiskers. S5-3. Under room temperature conditions, secondary modified silicon carbide whiskers were dispersed in N,N-dimethylformamide at a solid-liquid ratio of 1:(40~45). Nitrogen gas was introduced to remove oxygen, and the mixture was ultrasonically dispersed for 20 min with stirring at 300 r / min. Then, 25~30 wt% of triethylamine was added to the mixture. The mixture was then transferred to a water bath at 90℃ and stirred and kept at the temperature for 8 h. After the reaction was completed, the mixture was washed with deionized water and then vacuum dried to obtain the modified silicon carbide whiskers.

26. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 25, characterized in that: In step S5-1, the diameter of the β-silicon carbide whisker is 0.1~0.5μm and the length is 5-20μm.

27. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 1, characterized in that: The amphiphilic modified composite biomass material was prepared by the following method: S6-1. Take corn cobs and sawdust, dry them separately, crush them, and sieve them through a 200-mesh standard sieve to obtain corn cob powder and sawdust powder. S6-2. Mix corn cob powder and sawdust powder evenly at a mass ratio of (6~8):(2~4), add 50~55wt% of petroleum ether of the total amount of composite powder, and extract by Soxhlet extraction for 5 hours; filter dry by suction, add 50~55wt% of 85% ethanol solution of the total amount of composite powder and continue extraction for 3 hours; wash the product with anhydrous ethanol and then vacuum dry to obtain purified composite biomass powder; S6-3. Add the purified composite biomass powder to the alkaline alcohol solution at a solid-liquid ratio of 1:(28~33), purge with nitrogen to remove oxygen, seal, stir at 200 r / min at room temperature for 6~8 h, then raise the temperature to 60℃ and stir for another 2~3 h. After the reaction is complete, wash with deionized water and then vacuum dry to obtain activated composite biomass powder. S6-4. Using activated composite biomass powder as a substrate, phenol, glycidyl methacrylate, styrene, and N-hydroxymethylacrylamide are added at a mass ratio of 100:(25~30):(30~35):(8~12):(2~4). Deionized water is added to prepare a solution with a solid content of 20~25%. 0.8~1.0wt% of ammonium persulfate and 1.5~2.0wt% of sodium carbonate are added to the total amount of the system. The mixture is stirred evenly at room temperature. S6-5. Introduce nitrogen to purge oxygen, raise the temperature to 50°C, and stir the reaction at 300 r / min for 1-2 h. Then raise the temperature to 85°C and continue stirring the reaction for 2-3 h. After the reaction is completed, cool to room temperature, wash with anhydrous ethanol and deionized water in sequence, and then vacuum dry to obtain the amphiphilic modified composite biomass material.

28. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 27, characterized in that: The alkaline-alcoholic solution is prepared by mixing a 10% NaOH solution and anhydrous ethanol at a volume ratio of (3~4):(7~6).

29. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, or 22-28, characterized in that: The leak-sealing material is obtained by weighing amphiphilic modified flexible material, amphiphilic modified rigid material and amphiphilic modified biomass material according to the above mass ratio, putting them into a high-speed mixer, stirring at 1500 r / min for 20 min at room temperature, and mixing them evenly.

30. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 1, characterized in that: The modified sodium-based montmorillonite was prepared by the following method: S7-1. Take 100g of calcium-based montmorillonite, disperse it evenly in 1L of deionized water, add 5g of anhydrous sodium carbonate, heat to 65℃, stir and react at a constant temperature for 2h, wash with deionized water and dry to obtain sodium-based montmorillonite. S7-2. Take 50g of sodium-based montmorillonite prepared in step S7-1, disperse it in 1L of deionized water to form a uniform montmorillonite suspension, and adjust the pH to 8.5 with 0.5mol / L dilute hydrochloric acid. S7-3. Heat 500ml of deionized water to 75℃, then add 6g of dioctadecyl dimethyl ammonium chloride to the deionized water and stir at a constant temperature to dissolve, forming an aqueous solution of dioctadecyl dimethyl sodium chloride. S7-4. The aqueous solution of dioctadecyl dimethyl sodium chloride obtained in step S7-3 is added dropwise to the montmorillonite suspension obtained in step S7-2. The addition time is 30 min. After the addition is completed, the mixture is stirred at a constant temperature for 3 h. After the reaction is completed, the mixture is cooled to room temperature, centrifuged, washed multiple times with deionized water at 75 °C, and then vacuum dried and ground to obtain the modified sodium-based montmorillonite.

31. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The oil well cement is Grade G oil well cement, or oil well cement made by mixing Grade G oil well cement and Grade D oil well cement in a mass ratio of 8:

2.

32. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The heat-resistant reinforcing material is a mixture of quartz sand, microsilica, metakaolin, diabase powder and cordierite in a mass ratio of 60:18:12:5:

5.

33. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 32, characterized in that: The quartz sand has an SiO2 content ≥95% and a particle size ≥200 mesh; the microsilica SiO2 content ≥97% and a specific surface area ≥18000 m². 2 / kg; metakaolin SiO2 content ≥52%, Al2O3 content ≥38%, particle size ≥800 mesh; diabase powder SiO2 content ≥48%, Al2O3 content ≥15%, CaO content ≤8%, MgO content ≤6%, particle size ≥400 mesh; cordierite SiO2 content ≥49%, Al2O3 content ≥35%, MgO content ≥14%, particle size ≥325 mesh.

34. A high-efficiency plugging and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The weight-reducing material is prepared by mixing hollow glass microspheres, diatomaceous earth and sepiolite in a mass ratio of 70:20:

10.

35. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 34, characterized in that: The bulk density of the hollow glass microspheres is 0.38 g / cm³. 3 The compressive strength is ≥90MPa, and its D50 is ≤55μm; the diatomaceous earth has a SiO2 content ≥90% and a bulk density of 0.40g / cm³. 3 The particle size is ≥325 mesh; the sepiolite is β-sepiolite with a bulk density of 0.28 g / cm³. 3 The SiO2 content is ≥55%, the MgO content is ≥22%, the loss on ignition is ≤12%, and the particle size is ≥200 mesh.

36. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The anti-gas channeling material is a mixture of styrene-butadiene latex, nitrile latex, and nano-calcium carbonate in a mass ratio of 6:3:

1.

37. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 36, characterized in that: The styrene-butadiene latex is a carboxyl-modified styrene-butadiene latex with a solid content of 50%; the nitrile latex has a solid content of 50%; and the nano-calcium carbonate is activated nano-calcium carbonate treated with a titanate coupling agent with a particle size D50≤60nm.

38. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The micro-expansion material is prepared by mixing and compounding sulfoaluminate clinker, lightly calcined magnesium oxide, zeolite powder and wollastonite fiber in a mass ratio of 4:3:2:

1.

39. The high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in claim 38, characterized in that: The anhydrous calcium sulfoaluminate content in the sulfoaluminate clinker is ≥60%, and the specific surface area is ≥450m². 2 / kg; the calcination temperature of the raw material for lightly calcined magnesium oxide is 800~1000℃, and the particle size is ≥200 mesh; the specific surface area of ​​the zeolite powder is ≥420m². 2 / kg; Wollastonite fiber length ≤150μm.

40. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The water loss reducing agent is at least one of polyamides, polyvinyl alcohols, AMPS polymers, sulfonated styrene-maleic anhydride copolymers, and organosilicon-modified polymers.

41. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The retarder is at least one of tartrates, citric acid, boric acid, phosphates, lignin sulfonates, naphthalene sulfonates, aminosulfonates, and AMPS copolymers.

42. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The dispersant is at least one of carboxylates, polystyrene sulfonates, polynaphthalene sulfonates, lignin sulfonates, and ketaldehyde condensates.

43. A high-efficiency leak-sealing and anti-channeling cement system for shale oil and gas development as described in any one of claims 1-11, 13-17, 22-28, or 30, characterized in that: The defoamer is at least one of polyacryl alcohol, organosilicon, and tributyl phosphate.

Images