Abstract: A system comprising a semisubmersible, at least two offloading terminals and shuttle tankers in optional combination with an FSO may be deployed in deep water harsh environments where riser performance (either SCR or LWSCR) is a key performance parameter. The semisubmersible is used to support the risers because of its favorable motion characteristics under harsh conditions. The semisubmersible supports the entire process train and provides well maintenance, which may include water and/or gas injection. The semisubmersible may provide work-over capabilities for well intervention. The produced hydrocarbons are exported through flexible pipes to at least two off-loading buoys. A FSO or shuttle tanker receives the produced hydrocarbons. Two or more off-loading buoys may be employed to allow for uninterrupted production when a shuttle-tanker-only embodiment is utilized.

Abstract: In an offshore production system, a semisubmersible supports the risers and provides the service requirements for the wells, while an associated FPSO provides the processing functions and storage of the produced hydrocarbons. As a result, a greater number of risers can be supported in a harsh environment while the turret and swivel requirements of the system are significantly reduced.

Abstract: A vessel (14) that stores crude oil in tanks (12A-12H) in the vessel hull, maintains oxygen-free gas in the tank spaces (32) that lie above the crude oil. This is achieved by flowing in hydrocarbon-inert gas (gas that does not react with hydrocarbons), when crude oil is removed so the crude oil level drops, and by flowing out vent gas that includes the flowed-in hydrocarbon-inert gas and gaseous hydrocarbons that come from the crude oil, when crude oil flows into the tank and the oil level rises. A vacuum is applied to the vent pipe by connecting the vent pipe to an eductor (102) through which pressured gas is flowed. The hydrocarbon-inert gas is a fuel gas, which is a gas such as propane that is stored and used to fuel engines on the vessel.

Abstract: A vessel (14) that stores crude oil in tanks (12A–12H) in the vessel hull, maintains oxygen-free gas in the tank spaces (32) that lie above the crude oil. This is achieved by flowing in hydrocarbon-inert gas (gas that does not react with hydrocarbons), such as flue gas, when crude oil is removed so the crude oil level drops, and by flowing out vent gas that includes the inert gas and gaseous hydrocarbons that come from the crude oil, when crude oil flows into the tank and the oil level rises. An inert gas pipe (50) is used to flow inert flue gas into the tanks, and a separate vent gas pipe (52) is used to flow out the vent gas. A vacuum is applied to the vent pipe by connecting the vent pipe to an eductor (102) through which pressured gas, such as steam, is flowed. The vent gas is usually released into the atmosphere, but is burned when there is almost no wind, to prevent a buildup of hydrocarbon gas on the vessel deck.

Abstract: A vessel (14) that stores crude oil in tanks (12A-12H) in the vessel hull, maintains oxygen-free gas in the tank spaces (32) that lie above the crude oil. This is achieved by flowing in hydrocarbon-inert gas (gas that does not react with hydrocarbons), such as flue gas, when crude oil is removed so the crude oil level drops, and by flowing out vent gas that includes the inert gas and gaseous hydrocarbons that come from the crude oil, when crude oil flows into the tank and the oil level rises. An inert gas pipe (50) is used to flow inert flue gas into the tanks, and a separate vent gas pipe (52) is used to flow out the vent gas. A vacuum is applied to the vent pipe by connecting the vent pipe to an eductor (102) through which pressured gas, such as steam, is flowed. The vent gas is usually released into the atmosphere, but is burned when there is almost no wind, to prevent a buildup of hydrocarbon gas on the vessel deck.