Abstract: A conduit structure (44) connects subsea oil wells to a floating structure (12) such as a vessel, in shallow water, the conduit structure providing a low cost and reliable fluid connection during drift of the vessel. The conduit structure includes a seafloor riser support (50) with a lower end (52) fixed to the seafloor and an upper end (54) lying a plurality of meters above the seafloor. A flexible pipe or hose (46) extends in a double catenary curve from the top of the seafloor riser support, at a downward incline away from the seafloor riser support and then at an upward incline to the floating structure. A rigid pipe (70) can extend along a plurality of meters of the height of the riser support to minimize the required length of flexible hose and facilitate installation.

Abstract: A conduit structure (44) connects subsea oil wells to a floating structure (12) such as a vessel, in shallow water, the conduit structure providing a low cost and reliable fluid connection during drift of the vessel. The conduit structure includes a seafloor riser support (50) with a lower end (52) fixed to the seafloor and an upper end (54) lying a plurality of meters above the seafloor. A flexible pipe or hose (46) extends in a double catenary curve from the top of the seafloor riser support, at a downward incline away from the seafloor riser support and then at an upward incline to the floating structure. A rigid pipe (70) can extend along a plurality of meters of the height of the riser support to minimize the required length of flexible hose and facilitate installation.

Abstract: A conduit structure (44) connects subsea oil wells to a floating structure (12) such as a vessel, in shallow water, the conduit structure providing a low cost and reliable fluid connection during drift of the vessel. The conduit structure includes a seafloor riser support (50) with a lower end (52) fixed to the seafloor and an upper end (54) lying a plurality of meters above the seafloor. A flexible pipe or hose (46) extends in a double catenary curve from the top of the seafloor riser support, at a downward incline away from the seafloor riser support and then at an upward incline to the floating structure. A rigid pipe (70) can extend along a plurality of meters of the height of the riser support to minimize the required length of flexible hose and facilitate installation.

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.

Abstract: A disconnectable vessel mooring system including a storage vessel (10) with a turret (32) mounted therein so that the vessel is free to weathervane about an anchored turret. A spider buoy (44) in a docked position is received within the turret (32) with the upper part of the buoy at a position above the sea water level to permit dry servicing of the buoy (44). Anchor legs (68) in the docked position are secured to the turret (32) by securing means (71). Guide tubes (72) on the outer surface of the buoy (44) receive the anchor legs (68) therein for limited longitudinal travel. Selected anchor legs (68) may be disconnected from the buoy (44) when detached from the turret (32) for lowering onto the sea floor to reduce the weight of anchor legs supported by the buoy (44).

Abstract: A riser buoy (36) supports a plurality of risers (19) and is releasably docked within a generally cylindrical turret (20) of a floating storage vessel (10) at a location above the sea level (12) to provide dry access to quick disconnect/connect mating couplings (32, 40) on the turret (20) and riser buoy (36). A weight (58) connected by anchor chain (44) to riser buoy (36) is connected at its upper end to a retrieval line (60) which is controlled by a winch (62). Riser buoy (36) upon disconnection from vessel (10) is positioned at a predetermined submerged water depth below tanker traffic and high wave loads. Riser buoy (36) is docked within turret (20) independently of positioning means such as anchor chains (17) between the sea bed and the turret, or a thrusting positioning system including thrusters (16) of the vessel.