The shear strength and hydraulic permeability of the interface between well cement and casing was investigated using a triaxial direct shear apparatus. For the first time, these experiments provide measurements under controlled stress conditions with fluid flow measurements along the interface. The low cohesion (1.1 ± 1.1 MPa) and the high friction angle (43.4 ± 2.0°) indicates that the shear strength of the interface is provided by friction. This implies that the state of stress of the cement is critical to well integrity. The hydraulic aperture of the undamaged cement-steel samples was 6.8 ± 1.0 microns. Shear damage to the interface caused a decrease (-20 %) in hydraulic aperture for samples aged up to 1 month, and an increase (+300 %) for samples cured for two years. We performed numerical simulations to estimate the leakage potential from a carbon storage operation. This model predicts negligible leakage amounts (47 tonnes) in a shear-damaged well for the modeled injection of ∼1.26 million tonnes of CO₂. Thus, our measurements indicate that the cement-casing interface is not a significant leakage pathway in its intact or damaged state, and that shear-driven failure scenarios for this interface are not a significant risk to CO₂ storage security.

使用三轴直接剪切装置研究了井水泥与套管之间界面的剪切强度和水渗透性。这些实验首次提供了在受控应力条件下的测量结果以及沿界面的流体流量测量结果。低内聚力（1.1±1.1 MPa）和高摩擦角（43.4±2.0°）表示界面的剪切强度是由摩擦力提供的。这意味着水泥的应力状态对于井的完整性至关重要。未损坏的水泥钢样品的水力孔径为6.8±1.0微米。界面的剪切损坏导致老化至1个月的样品的液压孔径减小（-20％），而固化两年的样品的液压孔径减小（+ 300％）。我们进行了数值模拟，以估算碳储存作业的泄漏潜力。该模型预测，在模拟注入约126万吨CO的情况下，剪切损伤井中的泄漏量可以忽略不计（47吨）₂。因此，我们的测量结果表明，水泥套管界面在其完好或损坏状态下不是显着的泄漏途径，并且该界面的剪切驱动破坏场景对CO ₂储存安全性不是重大风险。