Thermomechanical analysis of leak-off test in salt formations: Axisymmetric multilayer modeling for vertical wells

Accurate prediction of formation breakdown pressure during Leak-off Tests (LOTs) in pre-salt evaporite formations is hindered by the heterogeneous and viscoelastic nature of salt rocks, which conventional models often oversimplify. This study introduces an axisymmetric multilayer thermomechanical model to overcome these limitations, integrating viscoelastic creep, fluid injection dynamics, and fracture propagation (PKN, KGD, Penny-shaped models) through finite element analysis. Validated against field data from three pre-salt wells, the model achieves high precision, with the PKN model yielding errors of 0.23 %, 0.006 %, and 0.38 % in leak-off pressure predictions across diverse lithological scenarios. By capturing the interplay of thermal, mechanical, and hydraulic effects, this model enhances well design, casing strategies, and operational safety in pre-salt environments. The model is limited to vertical wells and does not account for salt dissolution, warranting further research for broader applications.