Numerical modeling of triaxial tests on salt rocks using a creep law with damage-induced flow

Resumo

This work performs a numerical modeling of triaxial tests on salt rocks, using the Multimechanism
Deformation Coupled Fracture (MDCF) creep law and the software ABAQUS. In the design of wellbores drilled
on salt rocks for oil and gas exploration, computational modeling of creep is important for stability. Constitutive
models describe the salt behavior and are calibrated by laboratory triaxial tests. Brazilian salt rocks are usually
modelled using the double mechanism deformation, which is a good fit to several experimental tests. Yet, one of
its limitations is to describe only the steady-state stage. In the literature, some more complex models represent
salt creep, such as MDCF, which reproduces full creep stages and evolution of damage from the confining and
deviatoric stress. The damage mechanism influences the creep strain rate, especially under low confining stresses.
To achieve the proposed aim, the methodology adopted is divided into three main steps: i) numerical simulation
of triaxial tests using ABAQUS; ii) customization of ABAQUS to incorporate the MDCF; iii) validation of the
incorporation by comparisons with results available in the literature. The results show adequate responses for the
modeled triaxial tests under several conditions. The main contribution of this work is its use as a startup step for
the incorporation of the MDCF creep law in the modelling and verification of oil wellbore drilled on salt rocks
stability.