Buckling analysis for the long-term integrity evaluation of a hydrocarbon well

During the exploitation of a reservoir the displacements occurring in the near wellbore areas may induce mechanical actions on the well completions, including the steel casing and the cemented annulus, bringing to instability and failure of the well structure, with strong impacts on the economics of the field. The evaluation of the well completion integrity in the long-term is therefore a critical issue in the design phase. With reference to a synthetic case, the paper describes the procedure developed using Abaqus to evaluate the casing and cement integrity for a producing well. In addition to the evaluation of possible well damages related to the stress/strain evolution in the well completion, the well integrity assessment has been performed by forecasting the buckling risk in Abaqus/Standard at every production step. A safety factor related to the stability of the slender well structures has, thus, been computed and a sensitivity analysis has been performed on the characteristics of the steel used for the casing material. In conclusion, the results of the numerical simulations performed with Abaqus may provide highly valuable information and knowledge to build a proper design of the well completion, able to ensure the stability of the well during the whole production life of the field.