【摘要】 高温高压含水气相CO₂环境下，传统硅酸盐水泥易受酸性环境腐蚀，出现强度衰退、结构劣化现象。在水泥中掺入纳米SiO₂，可降低水泥石的Ca/Si比值和渗透性，从而提高材料的抗高温、耐腐蚀性能。纳米二氧化硅颗粒（NS）和溶胶（SS）是最常见的纳米SiO₂类型，但两种材料在水泥浆中的应用效果各有利弊。本文基于高温高压气相CO₂腐蚀实验，开展抗压强度、XRD、FTIR和SEM等测试，以探究不同类型纳米SiO₂对高温及腐蚀后水泥石力学强度、腐蚀产物和水化产物种类及微观结构的影响规律。结果表明，150℃高温养护后，掺入1%、2%和3%NS后，水泥石的抗压强度依次增加了1.82%、9.1%和15%，而掺入1%、2%和3%SS后抗压强度分别降低了7.73%、4.09%和2.73%。相对于G级油井水泥，分别掺入3%NS和3%SS，高温养护后水化产物中C-S-H凝胶的Ca/Si比分别降低了33.23%和24.37%,Ca（OH）₂含量降低，其中掺入NS使得水化产物Ca（OH）₂（001）晶面的衍射峰强度降低明显，改善Ca（OH）₂的晶面取向；腐蚀后水泥石抗压强度的衰退率依次降低了10.35个百分点和10.98个百分点，腐蚀产物CaCO₃减少，水泥颗粒之间胶结作用更强，水泥石耐腐蚀性能提高。综合对比腐蚀前后水泥石的力学强度及微观结构测试结果，NS对水泥石耐高温及耐腐蚀性能的改善作用优于SS。更多还原

【Abstract】 Under high temperature and high-pressure water-containing gas-phase CO₂ environments,conventional silicate cements are susceptible to corrosion by acidic environments,which results in strength decline and structural deterioration. Mixing nano-SiO₂ in cement can reduce the Ca/Si ratio and permeability,thus improving the material’s resistance to high temperature and corrosion.Nano-silica particles（NS）and sol-gel（SS）as the most common types of nano-SiO₂,but the application of the two materials in the cement paste has its own advantages and disadvantages. In this paper,based on the high-temperature and high-pressure vapor-phase CO₂ corrosion experiments,the compressive strength,XRD,FTIR and SEM tests were carried out to investigate the influence laws of different types of nano-SiO₂ on the mechanical strength,types of corrosion products and hydration products,and microstructures of the cement stone. The results showed that the compressive strength of cementite increased by 1.82%,9.1% and 15% sequentially at 150 ℃ with 1%,2% and 3% NS,while it decreased by 7.73%,4.09% and 2.73% with 1%,2% and 3% SS,respectively.Compared to the oil well cement,the Ca/Si ratio of C-S-H gel in the hydration product was reduced by 33.23% and 24.37%,and the Ca（OH）₂ content was reduced after mixing 3% NS and 3% SS,respectively. The addition of NS made the diffraction peak intensity of the hydration product Ca（OH）₂（001）crystal plane decrease obviously,and improved the crystal orientation of Ca（OH）₂. The decline rate of the cement compressive strength was reduced by 10.35 percentage point and 10.98 percentage point,and the corrosion products CaCO₃ were reduced,the cement particles were more strongly cemented,and the corrosion resistance of cement stone was improved. Comprehensive comparing the mechanical strength and microstructure of cement stone before and after corrosion,NS had better effect on improving the high temperature resistance and corrosion resistance of cement stone than SS.更多还原