Many gas discoveries are located far from shore in deep water environments. Without existing oil & gas offshore plants close to such fields, the main alternative is to develop a direct production tie-back to shore. Considering this philosophy, a study on a gas condensate field development located in 2000m water depth and 150km from shore has been conducted by TOTAL and Saipem. The proposed paper focuses on the description of the main issues regarding the development of a direct tie-back to shore, and presents associated innovative solutions to solve production issues and reduce costs.

The interest in lowering the number of flowlines to only a single gas export line with the use of subsea processing solutions (gas/liquid separation with liquid boosting and/or gas compression) will be explained. Replacing the mono-ethylene glycol (MEG) injection network by an anti-agglomerate solution will also be discussed. Finally, simplification of the main umbilical functionalities, use of subsea chemical storage and an all electrical control system will be presented. The paper will conclude by identifying the most interesting architecture to develop at a good cost and with a short planning period for this type of field.


After the recent discoveries around the world and global increase of gas demand, the offshore Oil & Gas industry is nowadays interested in exploring and developing ultra-deep gas fields. Considering the water depth and characteristics of these reservoirs, exploitation of such fields represents a technical and economic challenge. The study performed between TOTAL and Saipem is aimed at overcoming these difficulties and identifying the best way to develop an ultra-deep water gas field without topside facilities.

The area studied is a generic ultra-deep gas condensate field (WD=2000m) located 150km from shore. The paper will demonstrate the interest in single line development for such a long tie-back.

Two field architectures based on a single gas production line are proposed, considering different subsea processing solutions installed at mid-life to maximize gas recovery. The first architecture is developed with subsea gas/liquid separation, the other with subsea compression. Overall field development consideration and optimisation (including hydrate management, umbilical and installation) will be presented.

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