The Subdivision, General Arrangement, Structure Design And Checking Of Sandglass-type FDPSO

Floating Drilling Production Storage and Offloading is a multifunction floating platform, which has the integral function of drilling, production, storage and offloading, living and power as well. For the limitation of sensitivity to wave direction, severity of green water on deck, poor performance of heave motion of traditional ship, the Sandglass-type FDPSO is put forward, which is a new conceptual design with excellent hydrodynamic performance and deep water mooring performance. And this paper mainly includes three contents, namely the subdivision, general arrangement, structure design and checking.At first, in order to maintain the optimum hydrodynamic performance of platform such as heave and pitch performance during the whole production cycle, a new floating platform which can keep the float state and stability in the process of loading and unloading is put forward. On the basis of constant float condition, a new "geometric volume subdivision" is come up with and determine the style of subdivision, the number of cabins and bulkheads. Eventually, the feasibility of subdivision scheme is demonstrated from the initial stability and hydrodynamic performance.Secondly, the fundamental functions of drilling, production, storage and offloading of Sandglass-type FDPSO are generally introduced. Based on the fully understanding of the system operation process, the principal of general arrangement is proposed and the preliminary positions of each module are determined. Finally, the weight of the platform and the center of gravity position is estimated.Thirdly, the standardized design method is applied to determining the style of plate frame, the thickness and the size of girders and aggregates. And then, the finite element model is established to check the structure strength and design the structure again until meeting the strength requirement. After repeater design and checking, the plate thickness and type of steel, the size of girder and aggregate are ultimately determined.Fourthly, the traditional method that uses trochoidal wave theory and considers two typical states of the vertical and the arch is introduced to check the total longitudinal strength of the new FDPSO. Besides, the full load and ballast conditions are considered for the two typical working states of platform.At last, in order to consider the influence of wave impact, the CFD method is used to calculate the pressure distribution curve for the two-dimensional wedge section into water. And on the basis of three dimensional potential flow theory, a wave motion response is computed in one-year return period sea state. In the end, the wave impact pressure is applied to the finite element model and the local structure strength is finally checked.