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Collaborating Authors
Results
Design And Cost Study of Gravity-Based Substructure In the Sea of Okhotsk
Kamesaki, K. (NKK Corporation) | Shimazaki, K. (NKK Corporation) | Kasui, K. (NKK Corporation) | Matsumoto, H. (Japan National Oil Corporation) | Frederking, R. (National Research Council of Canada) | Timco, G.W. (National Research Council of Canada) | Sayed, M. (National Research Council of Canada) | Tseng, J. (Sandwell Engineering Inc.)
ABSTRACT This paper examines a preliminary design aimed at evaluating the cost of a gravity based structure in the Sea of Okhotsk. Emphasis is placed on a simplified design for the ice belt zone of the structure in order to reduce the cost. The present work includes a method for estimating first-year ice loads on the structure. The method consists of analysis of actual ice data obtained for the Molikpaq structure in the Beaufort Sea, combined with numerical simulations. The results give global ice loads forl00-year return period and a new pressure-area relation. INTRODUCTION The development of oil and gas in the Sea of Okhotsk faces several technical challenges, which reflect on the required capital expenditures. Reducing the cost of drilling structures is considered the key to success of that development. Such costs, however, remain uncertain. The uncertainty is mainly the result of the lack of well-defined functional requirements for the structures and corresponding designs. Ice loads on the structure are particularly considered to have a significant efl~ct on the design and cost of the structure. Therelbre, accurate ice load estimates and reasonable design methods are important Ibr developing cost effective structures. With this background, Japan National Oil Corporation, NK_K Corporation, the National Research Council of Canada (NRC), and Sandwell Engineering Inc. initiated a three-year research project in 1996, aimed at developing accurate estimates of ice loads and a reasonable structure design. In the first year, the influence of ice conditions on the design and ice load estimate methods were investigated. In the second and third years, field measurements were compiled and analyzed in order to obtain more accurate results, and preliminary numerical simulations were compared to other proposed load estimation methods (Frederking et al., 1999a and Timco et al., 1999b).
- Asia (1.00)
- North America > Canada > Ontario (0.28)
Survey And Maintenance of Oil Storage Vessels At Mooring Site
Muraoka, Eiichi (Japan National Oil Corporation)
Abstract Shirashima Oil storage base consists of 8 large oil storage barges. The barges are one of the largest floating structures in the world. The oil barges are being surveyed and repaired at mooring site from June 1999 to September 2000. The barges were supposed to be surveyed in detail at dry dock every 12 years. The dry-docking survey required transporting a barge from mooring site to the dry dock through the open sea and removing breakwaters at frequent intervals. In order to reduce the risks and cost of this work, the inspection and maintenance system at mooring site was examined and a new survey plan for the inspection and maintenance at mooring site was developed. This paper describes the summary of the new survey program and maintenance work at Shirashima base. The survey program can be applied not only to oil storage ships but also to all kinds of very large floating structures such as floating airports and floating container terminals in principle. Introduction National petroleum stockpiling activities and oil storage bases in Japan Japan National Oil Corporation (JNOC) began conducting national petroleum stockpiling activities in Japan in 1978 and completed stockpiling 50 million kiloliters of petroleum, which is a national petroleum target, in 1998. Fifty million kiloliters are stockpiled in 10 oil storage bases which are operated by 8 National Petroleum Stockpiling Companies established by JNOC and private companies. The oil storage bases are divided in four different systems, such as On ground tank system. In-ground tank system, Underground cavern tank system and Floating tank system. There are two bases of the floating tank system in Japan. One is Kamigoto oil storage base, which was entered into service in 1978 and is the first base in the world to use such system.