ABSTRACT:

Oil and gas wellbores experience a number of phases and scenarios during their lifespan. Drilling, completion, production and abandonment imply significant changes in the mechanical behavior of the well and its surrounding rock formation. Stress state and temperature changes are even more significant in Pre-salt wellbores since the creep behavior inherent to the salt rocks is strongly influenced by these state variables. This work presents a comprehensive Pre-salt wellbore integrity analysis addressing key phases of the well lifespan. Preventing casing from plastic deformations is recommended. The analyses were carried out with an in-house finite element simulator, GeoFlux3D, and have highlighted the wellbore casing sensitivity to the internal pressure and to the channels in the cement sheath. Plastic deformation has not been detected; however, the full evacuation periods and the cement channel affect negatively the casing integrity by triggering severe stress changes and non-uniformities, respectively. Therefore, proper definition of the loading and geometry scenarios to which Pre-salt wellbores are subjected is fundamental for reliable integrity predictions.

1. INTRODUCTION
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