Abstract

An overall conceptual design development of a deep sea FPSO suitable for the Gulf of Mexico area is described. The oil storage capacity was determined after the market screening by analyzing the answers to questionnaires submitted to potential field operators. The locations of turret, accommodation, topsides, flare boom and offloading equipment have been studied carefully before selecting the final location on the general arrangements. The basic drawings of general arrangements, lines, mid-ship section, accommodation layout and outfitting systems are developed. The basic hydrostatic calculations, stability, motions, mooring, structural and riser analyses are also carried out. The model tests are carried out at 2-dimensional wave flume for roll motion and wave model basin for global performances. In order to reduce the roll motion, a box-like mid-ship section is adopted with projected bilge keels. The model tests confirmed the expected good motion performances. A turret moored, one million barrels storage capacity, double hull FPSO is found to be most suitable in the Gulf of Mexico.

Introduction

The Gulf of Mexico was the last offshore oil field area not open for FPSOs. The absence of FPSOs from the GoM is partly due to the well-developed production and pipeline infrastructure. Another reason is the relative prevalence of gas developments in the GoM. As production enters deeper water and far away from any export infrastructure, the demand for FPSOs gets stronger. The final threshold to open the GoM for FPSOs was a safety confirmation. MMS (the Minerals Management Services) have expressed concerns about FPSO deployment, which have focused on the performance of offloading operations and the vessels' survivability during hurricanes in the GoM. According to the EIS (Environmental Impact Statement) recently issued by MMS, potential sitespecific impacts are essentially the same as with other deepwater development and production systems. The FPSO has been widely used as a most competitive production system concept in other offshore fields where infrastructure is not sufficient, or where the fields are marginal. As the water depth for offshore fields increases, more offshore operators have selected the FPSO concept. Considering the size of the oil reservoirs in the GoM, FPSOs will be widely adopted by the main operators.

On December 31st 2001 the MMS announced its decision to allow the industry to propose using FPSOs in the central and western Gulf of Mexico.

This paper presents an overall conceptual design development of a deep sea FPSO suitable for the Gulf of Mexico area. The locations of turret, accommodation, topsides, flare boom and offloading equipment have been studied carefully before selecting the final location on the general arrangements. Environmental conditions in the Gulf of Mexico, such as hurricanes, ultra-deep water depth and loop currents, required special consideration in the dimensioning and arrangements.

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