Modular or Turnkey FPSO; a World of Interfaces
Authors: Keolanui G. , Lunde P. , Jeannin O. 
Published: October 2008

FPSO development time cycles have been continuously reduced in recent times with a tendency to start viewing them as a modularly assembled commodity and at the same time, FPSO complexity is continually rising due to deeper water depth, greater amount of risers, harsher environments, tougher environmental and safety regulations and larger, more complex production facilities. The modular approach has the potential for neglecting the large number of critical interface engineering requirements which can result in costly and time consuming corrections. This Paper describes the interface design parameters which have to be considered between the various components or subassemblies which make up a typical FPSO such as the vessel, mooring system. subsea systems and topsides process equipment. lt further addresses the inherent iterative links between these parameters related to planning, designing, manufacturing and installation aspects. The interface engineering and design loop formulation required to develop a successfully integrated FPSO are presented. This interface engineering is a critical part of the work for assigned FPSO design teams to ensure that all engineering activities are carried out concurrently under common direction and goals. The resulting engineering deliverables ensure that each separate subassembly will mate together and operate as an integrated system during the FPSO's construction, assembly, testing and commissioning phases of development. Examples of interface engineering and construction methods used for two recently developed newbuild and converted FPSOs are discussed. The Paper suggests ideas which can reduce budget and schedule overruns resulting from improper interfacing on a typical turnkey type FPSO.

Introduction

Today. over sixty monohull type floating production storage and offloading vessels (FPSOs) have been installed in almost every area of the globe to develop offshore oil and gas fields. When FPSOs first arrived on the scene, beginning with the Castellon Field offshore Spain in 1977, they were heralded as the ultimate replacement for the fixed production platform in deep water locations, for marginal fields and in areas lacking the infrastructures needed to store and move the produced oil to refineries. FPSOs proved to be cheaper, faster to develop, very mobile and more practical in water depths over 1,000 feet and still are. As FPSOs have become more complex and project schedules have been squeezed to, or beyond the practical limits, some projects have suffered significant schedule and cost overruns. At times, there have been attempts to "assemble" an FPSO from components purchased from suppliers or fabricators with little appreciation for the complex interaction of the vessel, process, mooring and subsea systems. Problems which arise from this interaction in a shipyard or integration facility are primarily due to inadequately addressed interfaces. There must be a focused responsibility for the FPSO from a single turnkey contractor or from an operator having the resources and expertise to manage the details of a fast-paced, multidiscipline and integrated engineering and construction project. The contractor or operator should have:an organized project management team with clear lines of responsibilities and accountabilities andan experienced project manager to run the team under the precept that interface management is major part of his responsibilities.