The Turret Moored Platform (TMP) offers a unique design of floating production system that bridges the gap between semi submersible and tanker, yet retains the desirable characteristics of both vessel types. The TMP consists of a fully submerged lower hull for of storage positioned a small distance below a surface piercing hull with inter-hull columns connecting the two hulls. The concept. IS current.ly under consideration by a number of operators for target field locations In the UK and Norwegian sectors as well as offshore South East Asia and Australasia. This paper reviews the TMP concept and the major technical advantages gained through use of the design for floating production applications. The work discusses hydrostatic stability, wave induced motions, station keeping and structural loading. Particular emphasis IS placed on the survival capability of the vessel in cyclonic weather conditions with particular reference to the mooring system. These weather conditions are representative of those encountered in South East Asia. Analysis of the turret mooring system in a multitier directional environment is carried out including the effects of slowly varying daft forces on the vessel horizontal motions. The critical role played by damping forces is discussed together with its Influence on the extreme line tensions. An optimisation procedure to minimise intensions by choice of equilibrium line pre-tension angle IS outlined. The mooring analysis is extended to look at transient and steady state motions of the vessel during a line breakage situation.
As more offshore hydrocarbon discoveries become classified as marginal there is an increasing need to develop these fields with minimal exposure to economic risk whilst maintaining impeccable safety standards where protection of life and environment is of paramount concern. There is also a relatively long development time and large initial capital investment before cash flow.