Decommissioning of Umbilicals and Flexible Pipes - A Sensitivity Analysis in Decision-Making Process

Abstract The decommissioning of subsea equipment is a reality in Brazil and worldwide, highlighting the need for the development of decision-making methodologies for application in decommissioning projects. In Brazil, the volume of umbilicals and flexible pipes to be decommissioned in the future is huge and an analysis of the best decommissioning alternative would be desirable. Based on a decision-making methodology developed by a COPPE/UFRJ research group, this work aims to present the technical criterion for decommissioning decision-making process and a sensitivity analysis regarding the approach developed for this criterion. Among five different criteria, the proposed technical approach is composed of two sub-criteria — Complexity of Operations and Technological Risk — allowing us to assess the complexity of execution and operational activities of decommissioning alternatives and the technological risk associated with them. The decommissioning alternatives were divided into two groups — leave in situ and removal — and a total of six alternatives were considered in this study. The analyses developed to show the influence of different parameters in the methodology results emphasizes the robustness of the proposed methodology. Also, this work presents a preliminary indication for various decommissioning scenarios, varying combinations of water depth, structural integrity, cleaning status, and other factors. The results obtained in this work contribute to the consolidation of a robust methodology for the application and foundation of decision-making in decommissioning projects for flexible and umbilical lines.