American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
Many floating offshore storage systems are designed to operate on an oil/water displacement principle in which there is direct contact between the oil and the displacement water. One of these is the Shell Storage- and Loading Spar used in offshore oil field development. The high standards of purity of the displacement water required for environmental conservation makes the water disposal system a vital element in the design of the storage system.
The paper discusses the flow sheet and the important items such as low pressure drop hermetically closing check valves, pressure drop hermetically closing check valves, automatic measuring and alarm systems, and an oil-water separator developed specially for use on floating platforms.
The spar is a floating platform with a reduced water plane area giving it an attractive motion characteristic when subjected to the environmental forces of wind and waves. She derives her name from her long and thin shape (Fig. 1), which floats upright in the water like a sparbuoy. This floating platform may be utilized for various purposes in an offshore oil field, e.g. to carry a production separator station, water- or gas injection modules, a storage- and tanker loading terminal or other facilities. The maximum water depth in which a Spar may be used is in principle unlimited, the minimum depth is limited to approximately 200 ft since in shallow water it becomes increasingly difficult to locate the main buoyancy deep and still maintain positive stability. The first application of the Spar is as a storage- and tanker loading terminal and this terminal is presently on location in the Brent oil field area in the northern North Sea 100 miles off the coast of the Shetland Islands in 460 feet of water. She is owned and being operated by Shell UK Exploration and Production Ltd., a joint venture of the Royal Dutch/Shell Group and Exxon. (Ref. 1).
To allow operations as a terminal in open sea this Spar is provided with living facilities for the operators, power generators, tanks, loading pumps, oil skimmers, utilities and a single point mooring turntable with loading gear.
