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Contenu archivé le 2022-12-27

PERMANENT MOORING OF A FLOATING UNIT IN DEEP WATER BY MEANS OF A MULTIARTICULATED COLUMN

Objectif

Development of the articulated column technique for permanent mooring of a floating unit in 600 to 1,000 m water depth and North Sea or Mediterranean environments.
The general analysis phase has revealed the advantages of permanent mooring systems on a multi-articulated column for the development of deep water offshore fields. The reason is that there are many applications, ranging from simple buffer storage to the accumulation of the support functions of equipment for controlling and processing production, storage of the oil produced and its discharge via shuttle tankers moored in pairs or in tandem.
The main alternatives defined both for the architecture of the mooring structures and the fluid transfer system have demonstrated the existence of a wide variety of solutions for the technical problems set that will be selected to suit each specific case studied in the rest of the project.
In addition, specific work was devoted to the examination of problems raised by the eventual immersion of the upper part of the articulated columns in case of very violent storms. Arrangements were made to protect the rotary joints in case of accidental immersion.
The study also concerned the efforts exerted on the mooring arms owing to the slamming phenomenon.
Additional studies were carried out specific to the definition of a purpose built floating unit, associated to an articulated column
.
Feasibility studies have been especially devoted to the sizing of each structure "600-1000 m-Mediterranean Sea", "600-1000 m-North Sea". Their operational performances have been analysed in detail with both theoretical computations and experimental tests.
The scantling of each structure has been performed and the installation procedures have been reviewed by an expert company
.
This results in a new type of structure, whose feasability has been proved, available in many kinds of environment (including North Sea ), which can permanently moor a storage, or production and storage, and offloading floating unit (FSO/FPSO).
General analysis:
- definition of the requirements of the oil companies
- a review of the different mooring systems developed or now undergoing development for big water depth
- definition of the representative conditions of environment for both types of site (waves, wind, currents, soil)
- definition of typical production schemes for fluid transfer systems study
- review of the fluid transfer systems available (low and high pressure.
Preliminary projects:
- definition of the general structure of deep water columns
- development of methods for predimensioning and analysing the behaviour of the structures
Specific studies:
- application of weight-reducing materials for the construction of high pressure buoys
- analysis of fluid transfer systems along the column.
Feasability studies:
- definition of the joints (U joint and triaxial joint)
- definition of connection systems in order to ease the installation
- definition of bases adapted to different soil conditions
- definition of columns structures
- two series of model tests were performed to check the operational behaviour and the towing and installation operations
- installation procedures and maintenance procedures
- study of columns behaviour including dynamic behaviour and fatigue life
- cost estimates.

Appel à propositions

Data not available

Régime de financement

DEM - Demonstration contracts

Coordinateur

GERTH
Contribution de l’UE
Aucune donnée
Adresse
232 AV. NAPOLEON BONAPARTE
92500 Rueil Malmaison
France

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