This paper addresses the probabilistic analysis of casing tubulars, regarding the failure modes defined in API 5C3 code, which refers to the violation of elastic regime due to internal and external pressures, and axial force. The casing system performs important structural and isolation functions, ensuring the well integrity through its life cycle. The reliability-based casing design handles rigorously the uncertainties associated with the tube manufacturing, as variations in geometrical and mechanical properties, allowing to evaluate the probability of failure. It is presented a parametric analysis over different steel grades and tube slenderness, besides the application to a design scenario, by using Monte Carlo simulation and first-order reliability method. The results indicate that: collapse is the dominant failure mode; wall thickness and the yield limit govern the probabilistic response; the triaxial envelopes, revisited in a probabilistic framework, consist in a powerful tool, supporting the decision-making process in casing design.

中文翻译：

---

使用寿命极限状态下API套管强度的概率评估

本文针对API 5C3代码中定义的失效模式，对套管的概率分析进行了分析，该失效模式是指由于内部和外部压力以及轴向力而违反了弹性状态。套管系统执行重要的结构和隔离功能，在整个生命周期中确保井的完整性。基于可靠性的套管设计严格处理与管材制造相关的不确定性，如几何和机械性能的变化，从而可以评估发生故障的可能性。通过应用蒙特卡罗模拟和一阶可靠性方法，除了对设计方案的应用外，还对不同钢种和管材细长度进行了参数分析。结果表明：坍塌是主要的破坏模式；壁厚和屈服极限控制概率响应；在概率框架中重新审视的三轴封套包含一个功能强大的工具，可支持套管设计的决策过程。