Abstract: An arrangement and method are disclosed for providing a fluid flow path between a seabed supply of hydrocarbons and a turret moored storage vessel. A steel catenary riser interface buoy provides support for a steel catenary riser and the lower end of a flexible riser. This arrangement allows both risers to be pre-installed prior to arrival of the storage vessel or other floating storage facility. A turret interface buoy, secured to an upper end of the flexible riser is used in the installation process as well as in the hook-up of the riser system to the storage vessel.

Abstract: In certain offshore locations, for example off the West Coast of Africa, FPSO facilities provide an offloading facility to receive and load produced crude oil onto shuttle tankers. In such arrangements FPSO facilities use spread moored tankers with flowlines suspended in the water column to an offloading buoy or buoys which are located 1,000 to 1,500 meters away from the FPSO. Typically steel pipe flowlines as used with intermediate floatation to provide a suitable configuration that will avoid detrimental loads being imposed resulting from relative motions of the FPSO and the offloading buoy. According to the invention, a Suspended Pipe Line End Manifold (SPLEM) is connected to the end of the flowline assembly for support during towout. The SPLEM is positioned near the buoy and then connected at the sea surface to the bottom of the buoy by flexible leads such as anchor chains. The SPLEM is then flooded by selectively flooding compartments to cause it to sink to an operational position below the buoy.