地聚合物新型固井胶凝材料及其抗盐性能分析

针对深井高盐环境中水泥浆固井胶凝材料耐腐蚀性低的问题，提出了地聚合物作为一种潜在新型固井胶凝材料的可行性，并对其抗盐性进行了实验分析。通过测量粉煤灰+偏高岭土基地聚物和G级油井水泥在不同浓度盐溶液中养护28 d的抗压强度，发现水泥试件随着盐溶液浓度提高，强度损失增大，而地聚物试件的强度却随着盐浓度的提高逆势提升。通过XRF元素分析、XRD矿物分析、酸碱性分析发现，盐水环境中的离子交换显著改变了水泥的水化环境和生成物成分，导致其强度显著降低，但对地聚物的地质聚合反应产物影响甚微。扫描电子显微镜SEM下的形貌分析表明，盐水环境可使地聚物产生更加致密的微观结构，这是其强度提高的主要原因。该研究表明，早龄期地聚物具有优异的抗盐性能，可在进一步加强实验验证后考虑在深井高盐腐蚀环境中代替水泥使用。 

A New Geopolymer Well Cementing Gelled Material and Analysis of Its Resistance to Salt Attack

A geopolymer has been proposed to replace the low corrosion resistance gelled material used in cement slurries for cementing deep high salinity wells. Experiments have been done to study the resistance of the geopolymer to salt attack. A mixture of fly ash, metakaolin based geopolymer and class G cement was cured in salt solutions of different salinities for 28 d, and the compressive strength of the mixture was measured. It was found that with an increase in salinity, the loss of the compressive strength of the common set cement is increasing, while the compressive strength of the mixture is increasing with increase in salinity to the contrary. Element analysis with XRF, mineral analysis with XRD and analysis of acidity and alkalinity showed that ion exchange in saltwater environment remarkably changes the hydration environment and hydration product components of cement, resulting in remarkable strength loss of the cement. For the geo-polymerization of geopolymer, however, the effect of the ion exchange process is quite weak. Morphology analysis using SEM demonstrated that in salt water, geopolymer can form much denser microstructure, which is considered to be the main reason for the geopolymer to have an enhanced strength. This study showed that a geopolymer at its early age has superior resistance to salt attack, and can be used to replace cement in cementing deep high salinity wells after being verified with more experiments.