Faced with the challenge of a small reservoir located in 420 feet of water eight miles distant from the existing Tartan 'A' Platform in the U.K. sector of the North Sea, Texaco selected a subsea development plan to achieve both early production and full field development, paving the way to exploit 90-odd marginal fields known to exist in the North Sea.
With an innovative subsea design using gas lift and water injection manifolding in one template, electrical submersible pumps in the riser and flexible flow lines, this ended up being the world's first subsea tie-back with a subsea separator and slug catcher, which is still working today, and which has been the model for current subsea separation in deep water until now.
Detailed weight control involving removals as well as new design kept overall weight / space additions to a minimum. Careful planning of tie-ins and temporary re-allocations of production facilities allowed Tartan 'A' production to remain largely uninterrupted throughout the process. Close control of construction operations allowed the limited spare bed space on the platform to be used for construction personnel avoiding the expense of bringing Flotel equipment alongside.
The end result was not only one platform capable of handling two fiscally separate oil fields, but a thoroughly modernized computer controlled process facility as well.