Optimization of Underbase Drainage Systems for Gravity Structures on Sand

For many off-shore sites, gravity structures can provide cost-effective solutions for the provision of support to topside facilities. Uncertainties in drivability and longterm performance of piled foundations, particularly in new and unusual ground conditions, can lead to the adoption of relatively shallow foundation systems to carry the forces collected by the superstructure. Installation of a gravity structure can be undertaken without the requirement for an expensive heavy lift vessel in attendance while a steel jacket structure is set onto the site seabed and piled. The need for such a vessel at the platform site can be completely avoided if the topsides are mated to the structure in the construction yard or inshore. Furthermore, the large volumes associated with gravity structures can be utilised for oil storage off-shore.