Understanding the physico-chemical evolution at the steel-cement interfaces in geological CO2 storage environments

碳捕获和储存（CCS）是指从大型点源（例如发电厂、制氢设施、水泥厂和钢铁生产厂）捕获CO2，然后压缩并将CO2输送到适当的地下储层进行封存或强化采油的若干技术。然而，这些技术的实施需要长期的井筒完整性，以防止CO2泄漏回大气中。研究强调，潜在的临界失效点与套管水泥相关的碳酸化反应以及套管本身的外部完整性有关。据报告，CO2通过环空的泄漏比通过地层岩石的地质泄漏发生得快得多，导致经济损失、储存效率降低和储存位置受损。这种泄漏的可能性引起了对长期井筒隔离和水合水泥耐久性的相当大的关注。SLB的研究通过一系列长期暴露实验，审查了地质聚合物水泥与普通波特兰水泥相比具有更好的抗CO2性能的潜力。该项目旨在了解和量化地质聚合物水泥与波特兰水泥相比的抗CO2性，特别关注（i）在超临界CO2条件下碱活化水泥的散装物理化学演变和相关孔隙结构的评估，以及（ii）与此类水泥接触的套管材料的反应机制。该项目的成功完成将使我们能够了解两个过程的演变，同时在一个系统中，实验模拟钢-水泥界面，从而使局部生长/溶解在钢-水泥界面被理解和相关的倾向脱粘和CO2泄漏。

Carbon capture and storage (CCS) refers to a number of technologies which involve capturing CO2 from large point sources (e.g. power generation plants, hydrogen production facilities, cement plants and steel production plants), followed by compressing and transporting the CO2 to appropriate subsurface reservoirs for sequestration or enhanced oil recovery. However, the implementation of such technologies necessitates long-term wellbore integrity to prevent CO2 leakage back into the atmosphere. Studies have highlighted that a potential critical point of failure is related to the carbonation reactions associated with casing cement as well as the external integrity of the casing itself. CO2 leakage through the annulus is reported to occur much more rapidly than geological leakage through the formation rock, leading to economic loss, reduction of storage efficiency and compromise of the storage location. The potential for such leaks raises considerable concern regarding long-term wellbore isolation, and the durability of hydrated cement. Research by SLB has reviewed the potential for geopolymer cements to afford better CO2 resistance in comparison to ordinary Portland cement through a series of long term exposure experiment. This project is directed towards understanding and quantifying the CO2 resistance of geopolymer cements in contrast to Portland cement with particular focus on (i) assessment of the bulk physico-chemical evolution of alkali-activated cement and the associated pore structure, under super-critical CO2 conditions, and (ii) the reactions mechanisms of casing material in contact with such cements. The successful completion of this project will enable to understand the evolution of both processes simultaneously in a system which experimentally simulates the steel-cement interface, thus enabling the local growth/dissolution at the steel-cement interface to be understood and related to the propensity for de-bonding and CO2 leakage.