A new steel multi-well (112 headwells) platform was developed by Bohai Engineering and Design company in China. New Diversion Setting Foundation is adopted in this steel platform, which has rectangular deck supported by four large columns. Unlike conventional fixed platform, the platform used aerodynamic method for self-floating and being towed to the location to safely submerge to designed depth of seabed. To confirm the behaviour of the platform in transportation and submerging under several sea states, a series model tests have been conducted in CSSRC (China Ship Scientific Research Center). The results indicated that the behaviour of the platform is satisfactory. The advantages of the platform are reduction of engineering investment, installation time saving and it is estimated that the structure cost will cut down in 50%.

1. Platform Features
(1) Design Background of the Platform

For more than 20 years, Bohai Engineering & Design Company designed and installed about 30 platforms for different uses. Most of them were pile-base jacket platforms. Years of practical application shows that, for china the technique of design, manufacturing and installation for this kind of platform have met the international standard. However, there are still somethings to be improved for Jacket platform, Such as: Large amount of offshore work, more opportunities of sea state" s interference, long installation period in cooperating of thick mud on bottom, shallow penetration of jacket into mud and long pile span, the platform is liable to vibrate. On the mean time, wellhead conductor is exposing to the actions of waves and sea ice, which affect the Safety of the platform.

(2) Platform features

For solving these problems above, non-pile multi-well platform came to its design. This kind of platform consists of four large-diameter legs which are connected by two layers of trusses.

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