Geologic CO₂ storage (GCS) is a method to mitigate the adverse impact of global climate change. Potential leakage of CO₂ from fractured cement at the wellbore poses a risk to the feasibility of GCS. Foamed cement is widely applied in deepwater wells where fragile geologic formations cannot support the weight of conventional cement. Thus, it is critical to know whether fractures in foamed cement self-seal in a similar manner as conventional cement systems. This study is the first to investigate the changes in physical and chemical attributes of foamed cement under dynamic flow conditions using CO₂-saturated water. Self-sealing of fractures in the cement was observed at a solution flow rate of 0.1 mL/min and a pressure of 6.9 MPa. The formation of CaCO₃ precipitates in pore spaces and fractures led to a decrease in permeability by 1 order of magnitude. The extents of self-sealing in foamed cement samples, specifically the 20 and 30% air volume formulations, were similar to that of conventional cements. We attribute this to the greater alteration depth in the foamed cement, which compensated for the reduced availability of Portlandite and higher initial porosity. The results can be used to evaluate the risk of leakage associated with foamed cement.

中文翻译：

---

暴露于 CO2 饱和水中的破裂泡沫水泥的变化：对井完整性的影响

地质 CO ₂封存 (GCS) 是一种减轻全球气候变化不利影响的方法。CO ₂从井筒裂缝水泥中的潜在泄漏对GCS 的可行性构成了风险。泡沫水泥广泛应用于深水井，在这些井中，脆弱的地质构造无法承受传统水泥的重量。因此，了解泡沫水泥中的裂缝是否以与传统水泥系统类似的方式自密封是至关重要的。本研究首次使用 CO ₂饱和水研究动态流动条件下泡沫水泥的物理和化学属性的变化。在 0.1 mL/min 的溶液流速和 6.9 MPa 的压力下观察到水泥中裂缝的自密封。CaCO的形成₃孔隙空间和裂缝中的沉淀导致渗透率下降 1 个数量级。泡沫水泥样品的自密封程度，特别是 20% 和 30% 空气体积配方，与传统水泥相似。我们将此归因于泡沫水泥中更大的蚀变深度，这弥补了硅酸盐的可用性降低和更高的初始孔隙率。结果可用于评估与泡沫水泥相关的泄漏风险。