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Valve and Actuator Technology for the Offshore Industry
Published in Karan Sotoodeh, Coating Application for Piping, Valves and Actuators in Offshore Oil and Gas Industry, 2023
The fourth type of platform is semi-submersible, which is a special type of platform with legs or pontoons that provide buoyancy for the platform to float, and weight to keep the structure upright. Columns in the platform are used to provide stability, and pontoons connect the columns together. This type of platform, illustrated in Figure 5.6, can be used for multiple purposes, such as offshore drilling rigs and oil production. It is noticeable that the old semi-submersible platforms could have multiple purposes, but the newly designed, semi-submersible platforms are specifically designed for a unique purpose. As illustrated in the figure, this type of platform has large columns that are connected to large pontoons. A semi-submersible platform has some advantages, such as providing a large deck, exceptional stability on the sea and ocean, the possibility of being moved from one location to another, etc. This type of platform can be used for oil field development as deep as almost 3,000 m. All facilities, including valves, actuators and piping systems, are located topside on the top or deck of the jacket, as illustrated in Figure 5.6.
Introduction
Published in Srinivasan Chandrasekaran, Offshore Semi-Submersible Platform Engineering, 2020
Floating offshore platforms are position-restrained generally using the Dynamic Positioning System (DPS), which is referred to as the active-restraining system. Semi-submersible platforms are classified as floating facilities, which are position-restrained by mooring lines (Nguyen, 2010). Alternatively, Dynamic Positioning Systems (DPS) are also deployed for this purpose. Semi-submersibles comprise stationery floating hulls supported by pontoons that are tethered to the seabed with mooring lines. These mooring lines can be wire rope, chains, polyester, or any combination of these. Unlike a SPAR, semi-submersibles are not typically designed to accommodate dry-trees. They host one or more subsea systems, which may be deployed to one or more oil fields. Semi-submersibles usually export oil and gas via export risers that form the pipeline systems (Jensen et al., 2010; Niedzwecki and Liagre, 2003). The first FPS was a converted semi-submersible drilling rig, installed on Hamilton Oil Co. Ltd.’s Argyll field offshore the United Kingdom in June 1975. One of the most in-depth semi-submersible production units is Anadarko’s Independence Hub, commissioned in 2007, in Gulf of Mexico at a water depth of 2376 m. More details on the geometric forms and response analyses can be seen in further chapters. Figure 1.17 shows the schematic view of the Blind Faith semi-submersible.
Numerical simulation and experimental study on perforated heave plate of a DeepCwind floating wind turbine platform
Published in Ships and Offshore Structures, 2023
Wei Wang, Cheng Zhao, Panpan Jia, Zhiqiang Lu, Yonghe Xie
Drawing from the design classifications of floating offshore platforms in the oil and gas industry, floating wind turbines can also be categorised into four main types: spar-buoy, tension-leg platform (TLP), semi-submersible (column stabilised), and pontoon-type (barge-type) (Wang et al. 2010). Compared with other types, the semi-submersible platform has the advantages of a flexible setting water depth and convenient assembly and maintenance. Some countries are limited by their geographical location and ocean conditions, and thus semi-submersible platforms have become the first choice. The semi-submersible platform has a shallow draft, and the main body of the platform is located near the free surface of the ocean. The position and stability of an offshore wind turbine are maintained through a balance of gravity, buoyancy, and catenary tension. The heave motion of a semi-submersible platform can be affected by the heave plate, amplitude of the heave and pitch can be effectively reduced, and pitching motion can be improved (Jonkman 2007).