Flexible Subsea Storage Unit Development and Applications

The paper describe the KONGSBERG patented Subsea Storage Unit (SSU) technology and the ongoing Qualification Program. The SSU is characterized by using a flexible bag as oil / fluid storage. It's a gravity based storage unit that differ from conventional gravity storage systems by the flexible bag, which eliminates contact between sea-water and the stored fluid, thus eliminating the problems with emulsion layer and risk of bacteria growth. The bag is further covered by a protection structure, which accommodate the whole volume of the stored fluid thereby providing a second barrier should the bag rupture. There is free flow of seawater into the base of the protection structure and hence no needs to design against the water pressure. The top of the protection structure is designed such that the bag may be retracted separately from the storage tank if necessary for repair or replacement. Different fields would have variable storage needs and the ability to size, combine and manifold multiple SSU's provides attractive flexibility. The number of SSU's could also be varied over the field life and the paper present how the SSU is an enhancer for subsea processing and production in arctic areas and also how it may commercialize development of marginal oil field or tail end production.