Assessing the Applicability of Existing Burst Strength Models to Corroded Casing in Offshore CO2 Storage Wells

Reliable burst strength assessment of corroded casing is essential for wellbore integrity in offshore CO2 storage. Existing burst strength models were mostly developed in the pipeline context, and some have been introduced into downhole casing assessment because few casing-specific models are available. However, the basis and limitations of this transfer remain insufficiently clarified. This study assesses the applicability of five commonly used burst strength models for corroded casing, namely DNV, BS7910, CSA, SHELL92, and PCORRC. A finite element analysis method is established and validated to provide reference results for model assessment. The defect depth and length analyses first reveal overall model conservatism. Extending the analysis to casing steel grades exposes limitations in the material-strength representation of these models. Further analysis of the model formulations traces the observed conservatism and limitations to specific model components. The model assessment provides guidance for model selection and targeted correction, with DNV serving as a conservative reference for preliminary assessment and PCORRC offering a more promising basis for correction. More broadly, the findings provide a baseline for extending burst strength assessment to more complex loading and boundary conditions.