Abstract: A method for separating a multi-phase fluid, the fluid comprising a relatively high density component and a relatively low density component, the method comprising: introducing the fluid into a separation region; imparting a rotational movement into the multi-phase fluid; forming an outer annular region of rotating fluid within the separation region; and forming and maintaining a core of fluid in an inner region; wherein fluid entering the separation vessel is directed into the outer annular region; and the thickness of the outer annular region is such that the high density component is concentrated and substantially contained within this region, the low density component being concentrated in the rotating core.