CO₂ leakage through damaged wellbore cement sheaths is a major risk of geologic CO₂ storage (GCS), as conventional wellbore cement is brittle and can be damaged due to acid attack and downhole stresses during CO₂ injection. Here we examine a novel fiber-reinforced engineered cementitious composite (ECC) proposed as a substitute to conventional wellbore cement due to its superior ductility and intrinsic crack width control. ECC and conventional wellbore cement coupons were exposed to water in equilibrium with CO₂ at 50 °C and 10 MPa. The samples were retrieved after several days and their mechanical performance was evaluated using a four-point bending test, microhardness, and compressive strength analyses. Optical microscopy and mercury intrusion porosimetry were used to characterize the progression of the carbonation front and pore structures of the specimens. Control experiments were conducted under the same temperature and pressure conditions but with a N₂ headspace to isolate the impact of CO₂. It was found that carbonation increased the ultimate flexural strength of ECC but decreased its ductility. However, the ductility of carbonated ECC remained higher than that of conventional wellbore cements that exhibited brittle failure under all test conditions. Additionally, ECC exhibited minimal material loss and continued resistance to deformation in comparison to conventional wellbore cements. This suggests that while the exposure of ECC to CO₂ will alter its mechanical properties, altered ECC will continue to exhibit mechanical performance superior to conventional wellbore cement, and therefore shows promise as a highly durable wellbore cementing material for GCS applications.

由于损坏的井眼水泥套管而导致的CO ₂泄漏是地质CO ₂储存（GCS）的主要风险，因为常规井眼水泥易碎，并且在注入CO _2时会因酸侵蚀和井下应力而损坏。在这里，我们研究了一种新型的纤维增强工程胶结复合材料（ECC），由于其优越的延展性和固有的裂缝宽度控制能力，可替代传统的井筒水泥。将ECC和常规井眼水泥试件暴露在与CO ₂平衡的水中在50°C和10 MPa下。几天后取回样品，并使用四点弯曲试验，显微硬度和抗压强度分析评估其机械性能。光学显微镜和压汞法用于表征样品的碳化前沿和孔结构。在相同的温度和压力条件下进行控制实验，但要使用N ₂顶空以隔离CO ₂的影响。发现碳酸化增加了ECC的极限弯曲强度，但降低了其延展性。但是，碳酸ECC的延展性仍然高于在所有测试条件下均表现出脆性破坏的常规井筒水泥。另外，与传统的井眼水泥相比，ECC表现出最小的材料损失和持续的抗变形能力。这表明，尽管将ECC暴露于CO ₂会改变其机械性能，但改变后的ECC将继续表现出优于常规井眼水泥的机械​​性能，因此显示出有望作为GCS应用的高度耐用的井眼固井材料。