The safety and stability of the wellbore during geological sequestration of CO2 are of paramount importance. The accumulation of corrosive scale in the casing can result in local stress concentrations and increase the risk of damage to the cement plug. In this study, the stresses under the concentration-diffusion-controlled corrosion boundary are numerically solved using the boundary element method (BEM) based on the fundamental solution of the displacement boundary. The Mazars damage model was employed to analyze the damage sustained by the cement plugs, and the influence of the diffusion coefficient on this damage was examined across a broad spectrum of values. Ultimately, a predictive formula for the damage height of the cement plugs was proposed, along with a temporal prediction for the complete degradation of the wall. The results indicate that damage occurs more significantly in areas with high bicarbonate concentrations, while damage is often already present in regions with low concentrations. Furthermore, at higher diffusion coefficients, cement plugs sustain complete damage within a few years. In contrast, at lower diffusion coefficients, cement plugs can preserve long-term integrity for hundreds to thousands of years. The numerical stress solution presented in this paper effectively calculates the stress on the cement plug under the casing corrosion boundary. Additionally, the proposed formula for predicting damage height offers a foundation for safety practices and long-term reliability assessments in geological CO2 sequestration projects.

中文翻译：

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CO2地质封存中套管腐蚀作用下水泥塞的数值应力及损伤分析


在 CO2 地质封存过程中，井筒的安全性和稳定性至关重要。腐蚀水垢在套管中积聚会导致局部应力集中，并增加水泥塞损坏的风险。在本研究中，基于位移边界的基本解，使用边界元法 （BEM） 对浓度扩散控制腐蚀边界下的应力进行数值求解。采用 Mazars 损伤模型来分析水泥塞所遭受的损伤，并在广泛的值范围内检查扩散系数对这种损伤的影响。最终，提出了水泥塞损伤高度的预测公式，以及对墙体完全退化的时间预测。结果表明，损害在碳酸氢盐浓度高的区域发生得更明显，而损害通常已经存在于低浓度的地区。此外，在较高的扩散系数下，水泥塞会在几年内完全损坏。相比之下，在较低的扩散系数下，水泥塞可以保持数百到数千年的长期完整性。本文提出的数值应力解有效地计算了套管腐蚀边界下水泥塞上的应力。此外，所提出的损伤高度预测公式为地质 CO2 封存项目中的安全实践和长期可靠性评估提供了基础。