Method and system for gathering, transporting and marketing offshore oil and gas

A method has been provided for gathering, transporting, and marketing hydrocarbons from offshore fields (20A-20D). The method can include gathering different quality oils and then storing and/or segregating the oils according to such qualities. The oils can then be marketed, according to the qualities, to one or more locations via a floating vessel (50). In some configurations, the method can further include a gathering of gas and then processing of at least a portion of the gathered gas on the vessel (50). Gas processing techniques can include, among others, a compression of the gas, a generation of electricity, an internal utilization on the vessel (50), and a gas-to-liquids processing. The product of some of the processing techniques can, in turn, be marketed to one or more locations.