at the bottom of shell 164 the flow of water downwardly from above the module 152 comes either from optional deck drain flow lines not shown on platform 32 entering casing 58 immediately below the oil pad 310 or from the oil helix modules 152 located above lower oil helix modules 152 if there is only one oil helix module 152 and no deck drains there would be no flow down around the top oil helix if a plurality of oil helices 152 are used there would be no flow down around the top oil helix if there were no deck drain connections water entering the oil helix 152 through entrance 185 encounters the pipes 274 and swirls gently downward remaining in the reynold 39 s laminar flow regime based on stoke 39 s law oil particles flow counter currently to the water stream and rise upwardly through the oil helix oil will rise upwardly due to its lower density relative to water and the small droplets of oil will strike the underside of the vanes of the oil helices 152 adhere and travel upwardly along the underside of the vanes of the oil helices 152 into hole 186 as indicated by the arrows 186b the water continues to travel downwardly and joins the stream 192 after its exit from the bottom of the module thus the helical shaped vanes in addition to stoke 39 s law separation centrifugally force the water to the outside of shell 164 and the oil to the inside of the shell.