Carbonation of well cement under high-temperature and high-pressure conditions is a significant concern in geological sequestration projects. This study evaluates the carbonation-induced properties of low to high calcium-based one-part alkali-activated cements (AACs) as an alternative to Portland oil well cement under reservoir conditions. Fly ash/slag-based AACs exposed to saturated (SAT) and supercritical (SUP) CO₂ for 28 days were characterised using compressive strength, XRD and SEM tests. The strength properties of AACs increased with increasing slag content from 40% (low calcium AACs) to 100% (high calcium AACs) by weight of the binder under both SAT and SUP conditions. Aragonite is the major polymorph of CaCO₃ in all AACs, irrespective of the type of CO₂ exposure, and the highest aragonite content was observed in 100% slag AAC. The amorphous phase content decreased while the crystalline CaCO₃ increased in carbonated AACs with increasing slag content, resulting in a dense microstructure in high calcium AACs. Sealing of microcracks and pores was observed in high calcium AACs with the accelerated precipitation of CaCO₃ by reducing total porosity. Low calcium AACs resulted in a more highly porous carbonated microstructure than high calcium AACs under SAT and SUP conditions.

高温高压条件下井水泥碳化是地质封存工程中的一个重要问题。本研究评估了低至高钙基单组分碱活化水泥 (AAC) 在油藏条件下作为波特兰油井水泥替代品的碳化诱导特性。使用抗压强度、XRD 和 SEM 测试对暴露于饱和 (SAT) 和超临界 (SUP) CO ₂ 28 天的飞灰/矿渣基 AAC进行表征。在 SAT 和 SUP 条件下，AAC 的强度特性随着炉渣含量从 40%（低钙 AAC）增加到 100%（高钙 AAC）的粘合剂而增加。无论 CO ₂的类型如何，文石是所有 AAC中 CaCO ₃的主要多晶型物在 100% 矿渣 AAC 中观察到最高的文石含量。随着炉渣含量的增加，碳酸化AAC中的非晶相含量降低，而结晶CaCO ₃增加，导致高钙AAC中的微观结构致密。通过降低总孔隙率，CaCO ₃加速沉淀，在高钙 AAC 中观察到微裂纹和孔隙的密封。在 SAT 和 SUP 条件下，低钙 AAC 导致比高钙 AAC 具有更高孔隙率的碳酸化微观结构。