A Methodology for a Wellbore Casing Integrity Assessment in Scenarios of Salt Rock Dissolution

Dissolution in salt rocks can occur around injection wells when the injected water percolates through permeable rocks, reaching evaporite rock layers and developing cavities. This work focuses on the integrity of casings of injection wellbores in evaporite dissolution zones. Through a parametric investigation on the effects of cavity properties, lithology, and cement characteristics, casing behavior is assessed. Numerical analyses using the finite element method generate a database of this study. Salt rocks are modeled as elasto-viscoplastic materials, with creep simulated by the Double Mechanism Law. Cement and casing are modeled as elasto-plastic materials described by the Mohr-Coulomb and the von Mises criteria, respectively. The criterion for loss of casing integrity is the emergence of plastic deformations. The scenarios take into account different cavity geometry parameters (shape, size, and distance to the wellbore) and internal pressure values. Finite element model generation follows through templates developed specially for this problem. The results of the simulations point out the most relevant parameters and the critical scenarios. The experience gained in this work is of great importance for future studies and applications, adding up previous knowledge to new scenarios.