Análise estocástica de decisão multicritério para descomissionamento de dutos rígidos submarinos

Abstract

Decommissioning of subsea structures is gaining increased importance in Brazil as mature fields reach their end of life. Therefore, there is an increasing need for robust analyses on whether, when, and how to efficiently decommission subsea facilities. The aim of this paper is to provide a stochastic multicriteria decision analysis (MCDA) methodology to help the decision maker select the best alternative for decommissioning rigid offshore pipelines. A case study based on a rigid submarine pipeline located in the Cação field (Espírito Santo basin, Brazil) is presented to illustrate the applicability of the methodology. The following decommissioning alternatives are considered: leaving in situ with no further remediation, leaving in situ with rock dumping of pipeline ends, removing whole length by cut and lift, and finally, removing whole length by reverse S-lay. To evaluate decommissioning alternatives some aspects should be examined, such as technical and engineering aspects, safety considerations, marine and terrestrial environmental impacts, consumption of natural resources and energy, consequences on the activities of communities as well as economic aspects. The results indicate the total abandonment of the line as the alternative that best applies in this context, since the decommissioning option had already been determined.