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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.
Born national – going global
Published in Taran Thune, Ole Andreas Engen, Olav Wicken, Petroleum Industry Transformations, 2018
Helge Ryggvik, Ole Andreas Engen
What from the early 1970s seemed to become an internationally integrated open offshore supply market, from the mid-1970s became more or less closed national markets. As early as 1971, with the so-called ‘ten oil commandments’, formulated by the Norwegian parliament, the development of a local supply industry was established as a central part of Norwegian oil policy (Innst. S., 1970–1971). A political goal to develop a local industry did not in itself imply a strict protectionist policy. However, concerns from the two largest shipbuilding groups, Aker and Kværner, were important when in 1972 the government stated in a royal decree: ‘In cases where Norwegian commodities and services are competitive, in quality, service, delivery time and price, these are to be used’ (Royal Decree, 1972). Despite the Ministry of Industry’s insistence that ‘§54’, as it was later called, was not a protectionist measure, most parties involved knew that if the government wanted to use the paragraph actively, this offered an opening for the government to force operators to increase Norwegian participation (NOU, 1979). Norwegian shipowners saw the paragraph as an immediate threat, both to their international shipping activities and to their recent successful breakthrough in the semi-submersible drilling rig market. The paragraph, however, had little significance before the international economic crisis following the sharp rise in oil prices struck in 1974. At this time, Britain was also taking measures to protect its oil industry.
Design for resilience: Using latent capabilities to handle disruptions facing marine systems
Published in Pentti Kujala, Liangliang Lu, Marine Design XIII, 2018
S.S. Pettersen, B.E. Asbjørnslett, S.O. Erikstad, P.O. Brett
The Deepwater Horizon semi-submersible drilling rig exploded and sank after a blowout when operating the Macondo Prospect in the American section of the Gulf of Mexico, in April 2010 (Deepwater Horizon Study Group, 2011). The oil spill in the aftermath lasted for 87 days before the well was capped, and the leak stopped. The accident created an enormous, temporary demand for emergency response services that far surpassed the dedicated emergency response infrastructure, typically emergency response and rescue vessels (ERRVs). The resulting response effort consisted of a “fleet” of vessels, ranging from small privately owned boats, to fishing vessels, to US Coast Guard vessels, and to advanced offshore service vessels, working towards the common goal of reducing the impact of the accident (Graham et al., 2011, Mileski & Honeycutt, 2013).
Prediction of slamming pressure considering fluid-structure interaction. Part I: numerical simulations
Published in Ships and Offshore Structures, 2022
Dac Dung Truong, Beom-Seon Jang, Han-Baek Ju, Sang Woong Han
During service, ships and offshore structures are commonly exposed to impact pressures induced by slamming, sloshing and green water phenomena. Based on the region impacted by water, slamming events can be classified into three types of slam loads, namely bottom, flare, and stern slamming. When slamming occurs, structures are likely subjected to a slamming load with high pressure and short time duration. This load can cause local and global damages to structures. In the present study, bottom-type slamming (slamming acting on flat structures with zero or very small dead-rise angle) is investigated. In addition to slamming impacts on ship structures, slamming loads on the bottom deck hull of a semi-submersible drilling rig and/or the topside platform of spar structures also need to be studied.
Latent capabilities in support of maritime emergency response
Published in Maritime Policy & Management, 2020
Sigurd Solheim Pettersen, Jose Jorge Garcia Agis, Carl Fredrik Rehn, Bjørn Egil Asbjørnslett, Per Olaf Brett, Stein Ove Erikstad
In April 2010, the Deepwater Horizon semi-submersible drilling rig exploded and sank after experiencing a blowout when operating on the Macondo Prospect in the American sector of the Gulf of Mexico (Deepwater Horizon Study Group 2011). Oil spewed from the well for 87 days causing massive environmental damage before the well was capped. Eleven people lost their lives in the accident, and the fines paid by British Petroleum (BP) exceeded 50 billion USD (British Petroleum 2016). The response to the Deepwater Horizon accident involved ships ranging from US Coast Guard vessels to other available assets like offshore service vessels, fishing vessels, and smaller, privately owned boats (Graham et al. 2011). AIS (Automatic Identification System) data analyses show that offshore support vessel activity increased up to 40% the aftermath of the accident (Kaiser 2016). This ‘fleet’ collaborated towards the common objective of stopping the spill and reducing the environmental impact through oil recovery efforts. This was done even though ownership and management of the vessels were distributed across a variety of stakeholders (Mileski and Honeycutt 2013), and the vessels were intended primarily for other purposes, notably advanced offshore exploration, installation and production-related operations. The accident response shows that dedicated emergency response infrastructures were insufficient (Sylves and Comfort 2012), and that infrastructures for emergency response may need to piggyback on assets with useful design characteristics.
Vessel stability in polar low situations: case study for semi-submersible drilling rigs
Published in Ships and Offshore Structures, 2018
Adekunle Peter Orimolade, Svein Larsen, Ove Tobias Gudmestad
A typical sixth generation DP3 and moored harsh environment semi-submersible drilling rig (North Dragon), with the capability for operations in the Barents Sea is considered in this study. The perspective view of the semi-submersible, modelled using the Maxsurf software program (Bentley Systems 2017) is shown in Figure 4. A weight summary of the semi-submersible in the different loading conditions is presented in Table 1.