A Decision Model for Optimum FPSO Acquisition and Management
Authors: Ray Tapabrata , Mallick Sandip K. 
Published: October 2008

FPSO is an acronym for floating production storage and offloading system which combines the production, storage and offloading capability into a single facility. Over the last thirty years, FPSOs proved to be the most promising floating production concept because of its flexibility in operation. The current practice of selection among alternative concepts of FPSO is largely based on decision makers experience and in most cases is not evaluated through a structured decision model. Thus the current ill-structured decision making process suffers fiom the problem of incommensurable unit handling and conflicting requirement analysis. Moreover, the process of selection is even more complex in the domain of concept selection as it involves decisions in presence of imprecise and incomplete information of the future. With a rapid increase in the use of FPSOs and its possible variations in features, the chances of making wrong decisions have also grown up substantially establishing a serious need to develop a decision model for optimum FPSO acquisition and management. In this paper, a decision model is proposed to handle the selection among alternative concepts of FPSO configurations. The proposed decision model is capable of handling alternatives involving tanker conversions, new-buildings with various economic and performance features which involve subjective attributes of assessment in addition to the conflicting field requirements. Apart from supporting the decision maker in the selection process, the model also adds accountability to the selection process as the decision maker's preferences are captured through pairwise comparisons between the alternatives and the criteria. The model can be readily used to establish the stability of the outranking alternative under the simulated operating scenario. A simple case study has been taken up to illustrate the methodology of optimum FPSO selection using the structured decision model.

Introduction

The advent of FPSOs begun since 1976, the first FPSO was installed in the same year for the Castellon Field, offshore Spain. The basic fluid transfer technology and mooring system configuration evolved fiom the already available knowledge and experience gained from Offshore Loading Terminals, Floating Storage Units(FSUs) and Floating Storage and Omoading Units(FS0s). FPSOs wide spread use is largely attributed to its effective and cost viable solution for both early as well as marginal fields.

Similar to the evolution of other types of platforms, the FPSO concept has already been through a number developments in mooring, processing and shipboard systems. The initial tanker based units with classical mooring systems have given way to new vessels equipped with dynamic positioning(DP) assistance, sophisticated permanent turrets or dis-connectable mooring systems. Co-ordination between various groups/builders are becoming more and more important for the success of the project requiring adequate decision support throughout the entire planning and the development phases.

Decisions taken by various agencies e.g. owner/ builder/representatives or suppliers are usually not numerically supported and currently rely on qualitative judgement through subjective assessment and often fancies. The following section briefly discusses the current process of decision making involved in FPSO acquisition and management.