MULTI-OBJECTIVE OPTIMISATION AND ITS APPLICATION TO CONCEPT DEVELOPMENT IN FLOATING OFFSHORE SYSTEMS

Abstract

This paper addresses the need for a rapid, multi-disciplined and rational approach to floating system concept development and selection during the very earliest stages of project definition. It describes the implementation of a modified multi- objective Genetic Algorithm for this purpose. A formulation of the NSGA-II algorithm is combined with additional Target Functions to reduce otherwise large multi-disciplined problems to more tractable solution using tools commonly available in the design office. It also provides a rational basis for the comparison of different design solutions each of which are Pareto Optimal with respect to the technical and economic performance of each underlying concept. A specific example of marginal field development using a novel FPSO concept is presented. Starting with just the oil field location and reserves estimate, the algorithm provides the means to define preliminary hull form and production facility capacities, match performance to payload, and give preliminary indicators of likely investment performance. The method may also be applied more generally in preliminary ship design, particularly where it is possible to model economic performance alongside efficiency, safety and key technical factors in hydrodynamics and structures.