Inter J Nav Archit Oc Engng (2010) 2:155~170 DOI 10.3744/JNAOE.2010.2.3.155
Issues in offshore platform research - Part 1: Semi-submersibles
R. Sharma1, Tae-Wan Kim2, O. P. Sha3 and S. C. Misra4
Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai, India. Department of Naval Architecture and Ocean Engineering, Research Institute of Marine SystemsEngineering, Seoul National University, Seoul, Republic of Korea. 3 Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology Kharagpur, Kharagpur, India. 4 Indian Maritime University, Visakhapatnam Campus, India.
ABSTRACT: Availability of economic and efficient energy resources is crucial to a nation’s development. Because of their low cost and advancement indrilling and exploration technologies, oil and gas based energy systems are the most widely used energy source throughout the world. The inexpensive oil and gas based energy systems are used for everything, i.e., from transportation of goods and people to the harvesting of crops for food. As the energy demand continues to rise, there is strong need for inexpensive energy solutions. An offshoreplatform is a large structure that is used to house workers and machinery needed to drill wells in the ocean bed, extract oil and/or natural gas, process the produced fluids, and ship or pipe them to shore. Depending on the circumstances, the offshore platform can be fixed (to the ocean floor) or can consist of an artificial island or can float. Semi-submersibles are used for various purposes inoffshore and marine engineering, e.g. crane vessels, drilling vessels, tourist vessels, production platforms and accommodation facilities, etc. The challenges of deepwater drilling have further motivated the researchers to design optimum choices for semi-submersibles for a chosen operating depth. In our series of eight papers, we discuss the design and production aspects of all the types of offshoreplatforms. In the present part I, we present an introduction and critical analysis of semi-submersibles. KEY WORDS: Deepwater drilling; Semi-submersible; Mooring systems; Maneuvering characteristics.
An offshore platform is a large structure (floating or fixed) which is used to house workers and machinery needed to drill wells in the ocean bed, extract oil and/or natural gas, processthe produced fluids, and ship or pipe them to shore. Based upon the geographic location a platform cab be fixed to the ocean floor, can consist of an artificial island, or can be a float structure. The offshore platforms can be classified on the basis of operating water depths, and the two classifications are: shallow water offshore platforms and deep water offshore platforms. Also, the offshoreplatforms can be classified on the basis of their objective, and the two classifications are: drilling offshore platforms, storage offshore platforms and drilling/storage/offloading platforms. The shallow water offshore platforms can be of two types: fixed offshore platforms and floating offshore platforms. The classification of the offshore platforms is listed in Table 1. Till recently, theproduction economics ensured that most of the offshore platforms were located on the continental shelf at shallow water depths. However, because of drying resources at the shallow water depths and with advances in
Corresponding author: Tae-Wan Kim e-mail: firstname.lastname@example.org
technology and increasing crude oil prices, drilling and production in deeper waters has become both feasible and economicallyviable. This has given rise to the more interest in to the deeper water platforms. In general, an offshore platform can have around 30~50 wellheads that are located on the platform and directional drilling allows reservoirs to be accessed at both different depths and at remote positions up to 10~15km from the platform. The remote subsea wells are connected to the platform by flow lines and by...