Numerical investigations of cement interface debonding for assessing well integrity risks

Loading history during drilling, completion and operations of the well can affect wellbore integrity. Debonding along well cement interfaces leads to the creation of micro-annuli and potential leakage pathways. We investigate the risk of debonding by modeling the integrity of an example well throughout its life-time using a finite element analysis tool. Well cement properties under downhole conditions are uncertain and therefore treated in a probabilistic manner. Simulation results for an example well show that a flexible annular cement reduces the risk of debonding and creation of micro-annuli along well cement interfaces. A quantitative measure of risk reduction is provided by probability density functions. Overall, probability functions of model output parameters from simulations with real well data can be used as input to a well integrity risk assessment framework that can incorporate diverse data and uncertain information.