Abstract: The invention relates to a concept for controlled containment of oil and condensate and possibly other types of liquids and chemicals in constructions as a possible failure of the conventional prior art barriers used in offshore petroleum exploration and production activities, intended for use at several water depths. The concept comprises a support structure (10) and a deck structure (14) positioned on top of the support structure (10), from where drilling may be performed, and where possible spillage of hydrocarbons from the drilling or production activities, in case of failure of the conventional barriers, will be contained and directed in a controlled manner to collecting storage tanks (46) integrated in the support structure (10).