NOVEL PRODUCTION CONCEPTS FOR DEEP WATER AND ASSOCIATED HYDRODYNAMIC PROBLEMS

Abstract

Offshore oil and gas production is now reaching to great depths, in excess of 1000 m, in the Gulf of Mexico and the Campos Basin, offshore Brazil. It will not be long before Australian companies look towards probable reserves in deeper waters that still remain within the Australian exclusive economic zone. Production concepts for deep and ultra deep water thus need to be studied and researched, and a constant watch should be maintained on developments around the world in this area.

This paper presents two popular, and constantly evolving, concepts for deep water, namely: tension leg platforms (TLP) and spars. Tension leg platforms have been in existence for about 14 years, and are actively sought for deep water by worldwide operating companies. They are vertically moored by means of taut tethers which present interesting motion characteristics and unique hydrodynamic problems. Spar platforms are currently being installed for production purposes. These are large deep draft cylindrical structures moored by catenary or taut spread mooring systems. Physical details, advantages and limitations of both systems are discussed.

While many aspects of these production systems are now understood, there are still several unknowns. Deeper waters translate to newer problems. Potential problems of the future are discussed in this paper, and research needs are highlighted.