In shallow water, the motion performance of a single point moored 320 kDWT FPSO is investigated in 100-year environment conditions with different water depths. The ratios of the water depths to the draft are within the range from 1.3 to 1.1. Both numerical calculation and experimental research are carried out in this paper. The results of the calculation and the model test are compared and analyzed. It is shown that with the decrease of the water depth, the wave frequency motions of the FPSO decrease obviously. The research result is expected to be used in optimizing design of the FPSO in the oil fields with shallow water.
The need for oil increases rapidly during the past twenty years, which leads to world-wide demand for floating production and storage vessels. FPSO (Floating, Production, Storage and Offloading units) has been recently established as attractive alternative for the exploitation of offshore oil field because of its flexibility, reliability, the low cost and adapting for the variety of water depth. In China, there are 9 FPSOs working in the South China Sea, the East China Sea and the Bohai Bay. And the amount of FPSO is still growing (MaoYongjun, 1998). In China, so far the most attractive and abundant oil exploitation area is in the offshore of Bohai Bay, which is a shallow water area with the water depth of only about 20–30m. The added masses and damping coefficients are calculated by the linear 3-D potential theory and the wave frequency motions are determined by means of time-domain computations according to Cummins impulse response technique. The model tests in 100-year condition, including the collinear wind and wave and the crossed current, were carried out in the ocean engineering basin of the State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University.