Abstract: A separator for removing oil from a fluid mixture at a well site. An elongated conduit is arranged for support on an offshore structure and extends downward into a body of water into which cleaned water is to be discharged. The process fluid flows downward in the conduit past a series of baffles and out the lower end into the body of water. Quiescent regions at each baffle allows oil droplets to migrate into entrapment regions and be withdrawn up a riser connected to each entrapment region. A mixture inlet tube extends down to discharge below the topmost baffle. A fluid enclosure above the topmost baffle accepts the collected oil. An oil collection box is situated in the fluid enclosure and receives oil directly from the riser, some of which is allowed to flow out openings into the enclosure. An oil outlet standpipe collects oil from the oil box for removal.