Optimization of Legs Batter In Fixed Offshore Platforms

Fixed offshore platforms are commonly utilized for various purposes including offshore drilling, processing and support of offshore operations in Persian Gulf. Jacket type structures are appropriate for relatively shallow water areas. A jacket is a supporting structure for deck facilities stabilized by leg piles through the seabed. The size of a jacket depends on deck size, pile dimension and environmental loads. Since these structures are very expensive, weight optimization could reduce their capital investment. In the current study, the effect of legs' batter on the overall cost of platform is investigated by comparing the weight of jackets with different batters. All jackets studied here, are located in 70 m depth of Persian Gulf. These jackets are modeled in SACS finite element program under the same load conditions. After the in-place and seismic analysis, the weight of pile and jacket for each batter is determined. Finally, variation of platforms weight in comparison with leg batter for in-place and seismic analyses have been obtained and the platform minimum weight has been identified. Finally, the relevant leg batter of the platform with minimum weight is selected as the optimum one.