Well integrity may be defined as the capability of the well to prevent leakage into the environment, which is a very important feature for oil and gas wells. A way to prevent leaks during operation is to perform maintenance interventions, seeking to keep redundancy in the well’s safety barriers....

Well integrity may be defined as the capability of the well to prevent leakage into the environment, which is a very important feature for oil and gas wells. A way to prevent leaks during operation is to perform maintenance interventions, seeking to keep redundancy in the well’s safety barriers. Cost assessment regarding the wells maintenance interventions should be done during the initial phases of the production development project, when the construction campaign is both technically and economically evaluated. This paper presents an approach for development wells integrity analysis considering the existence of intermediate stages, when the integrity has not been lost but the well is considered to be in a degraded status. The method is based on the barriers integrated sets (BIS), proposed by Miura (A study on safety of construction and repair in offshore oil and gas wells (in Portuguese). PhD thesis, University of Campinas, Brazil, Campinas, 2004) and described by Miura et al. (J Pet Sci Eng 51:111–126, 2006), and on general reliability engineering techniques. The approach may be used for maintenance interventions resource assessment considering a well construction campaign. Furthermore, through the determination of the mean time to failure of each BIS identified in the completion configuration it is possible to estimate when the well is in a degraded status, relying on a single BIS, and when the well is expected to leak

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