Application of an Alternative Concept in Dynamic Positioning to a Tanker Floating Production System
Author N.J. Davison and N.T. Thomas (BP Shipping) and U. Nienhuis and J.A. Pinkster (MARIN)
Title Application of an Alternative Concept in Dynamic Positioning to a Tanker Floating Production System
Conference/Journal Offshore Technology Conference (OTC), Houston
Paper no. OTC1987-5444
Month May
Year 1987

Abstract
This paper describes the development of a cost-effective floating production system, comprising a conventional tanker fitted with a dynamic positioning (DP) system to maintain the riser connection to the well head.

Reduced costs in the DP system are achieved by using a control strategy based on thrusters at the forward end of the vessel thus allowing the vessel to rotate freely, i.e. weathervane, to the environment. A description of the principles of this control strategy is given.

Application of this DP system to a conventional tanker is briefly outlined. Special attention was required in the location of the thrusters in the forward cargo tank and a description is given of the numerical studies and model tests used to optimise thruster location.

In order to gain insight into vessel behaviour under such a DP system, simulation studies were carried out and the results correlated with model tests in a wind, wave and current environment. These results indicated the need for a thruster at the aft end of the vessel under certain environmental conditions.

The paper concludes with an economic assessment of the operational costs of such a DP system, which together with reduced thruster and power plant costs presents an attractive solution to production from marginal fields.

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