An Application of Fault Tree Analysis for Decommissioning of Subsea Flexible Pipeline in Brazil

The decommissioning of underwater structures has expanded in recent years, as the number of facilities at the end of their useful lives is increasing and legislation becomes more severe. Unlike the production units which already have their decommissioning plans consolidated, subsea pipelines represent the greatest technological, environmental and financial challenge of this stage. Currently, there are few studies to evaluate failures in the decommissioning of flexible pipelines. In addition, these studies generally use simplified analyses. Therefore, this study aims to elaborate a failure analysis for a Reverse Reeling option, in order to contribute to the decision-making process and reduction of failures. For this, a Fault Tree Analysis will be developed followed by the subsequent elaboration of its minimum cut sets. The main results present a total of 13 first-order minimal cut set, 5 second-order minimal cut set and 7 third-order minimal cut set.