| With the development of industrial technology , our national demand for the resources such as petroleum and natural gas has been increasing day after day. As the land resources are running out at a high speed, the petroleum and natural gas exploration and exploitation is gradually turning to the deep seas and oceans. Although our country depend much on the imported petroleum, yet we have huge amount of petroleum and gas reserves in the ocean areas. Therefore, it is urgent for our country to strengthen the research and development ability in marine facility. In the past two decades, FPSO has become the most popular exploitation approach of the marine oil and gas field. FPSO is different from the ordinary shipping boats in that it is moored in the sea on the long-time basis. This makes the out transportation of the marine petroleum and natural gas an indispensable task. In the process of transportation, the real-time change of the ship draft and interaction between ships will occur, which can lead to the hydrodynamic performance change of the ship, thus increasing the risk coefficient of operation. Therefore, it is a project of great significance to study side docking ,out transportation and hydrodynamic performance.This paper takes a sample FPSO of 150000-ton and an ordinary sample shuttle tanker of 100000-ton as study subjects, with the water depth 200 meters. First, the hydrodynamic performance of a fully-loaded FPSO is discussed. Meanwhile, it studies and compares the hydrodynami performance of FPSO and side docking system of shuttle tankers. It reports the experiments in the peaceful pool, such as Hydrostatic attenuation, regular and irregular waves which attempt to prove the correctness of the results from the digital simulation. Also,the features of wind loading and current loading of FPSO and single floating shuttle tanker are studied and compared. Finally, this paper analyzes the time domains of FPSO and a side docking system, considering the security of out transportation in the South China Sea and trying to optimize the multi-point mooring and side-docking system. The specific contents are as follows.(1) In order to study the mutual impact of hydrodynami performance between FPSO and shuttle tankers, this paper analyze the ship drafts when a fully-loaded FPSO floats separately and when it is side-docking near a shuttle tanker, the associated mass, radiation damping RAO and the variation trend of wave force when FPSO is mooring near a shuttle tanker at different distances. Studies show that the existence of the side docking shuttle tanker considerably influences the hydrodynami performance of the FPSO. This can be mainly seen in that horizontal wave force and motion response can occur when waves goes against FPSO. The variation of ship drafts can similarly influence the hydrodynami performance of ships. Among them, the rolling response of unloaded shuttle tankers will go up greatly around 0.75rad/s while it will respond slightly when fully loaded. As the side docking distance gets smaller and smaller, the horizontal load and motion response will correspondingly increase.(2) To prove the correctness of the hydrodynami performance of FPSO and the side-docking system of a shuttle banker, experiments in pool were carried out. Restricted by the depth of the pool water, the researcher designed truncated mooring cable in the direction of the water depth, and did the hydrostatic attenuation experiments under the conditions of shuttle banker, FPSO , and multi-point mooring. From these experiment, the the researcher has got important parameters of eigen period and attenuation coefficient. Under the condition of horizontal compliant mooring of FPSO and shuttle banker, regular wave experiment was conducted and from the experiment, amplitude response operator was got.Under the sea condition of South China Sea, irregular wave experiments were done, from which motion time domain response curves and mooring line tension curves for multi-point mooring FPSO and shuttle bankers moored by side docking were obtained.(3) At present, the study about ship wind load and current load is generally based on the established empirical formula. However, because of the disturbance from FPSO and shuttle bankers in the wind field and flow field, the correctness of the established empirical formula is also influenced. Therefore, the wind field and flow field models of FPSO and shuttle bankers are created to study the wind load and current load. This study takes the influence of flow rate, ship draft and side-docking gap into consideration and compares curve changes of current load variation with flow rate change with the curves of FPSO and floating shuttle banker. The above studies show that though the influence of ship on the flow field is complex, current load is in inverse proportion to flow rate squared. The studies also suggest that current load is extremely sensitive to the change of ship draft, and in certain cases, the phenomenon of current load going inversely may occur. The change rules of wind load are similar to those of current load.(4) In the study, time domain analysis model was established based on the multi-point mooring and side-docking systems of the experiment models, and also, three hours' analysis on time domain was conducted according to the experimental condition. The result is that the motion response deviation does exist in the direction of surging, swaying and yawing,while the motion responses in the direction of swaying, surging and heaving are in better accordance. Meanwhile, Meanwhile, the collected tension data of multi-point mooring rope and side-docking system rope are , to some extent, a little bigger than experimental data, but their tendency is in good accordance. Moreover, through the time domain analysis , this study analyzed the optimizing the multi-point mooring ropes of FPSO and side-docking system ropes. In this analysis, it has been discovered that when the water depth is 200 meters, the traditional three-stage chain is not the best choice for multi-point mooring. The steel rope chain can bring about better effect. Anchor points can similarly influence the effect of multi-point mooring. The studies also found that when mooring rope and the profile are at 60 degree angle, the mooring effect is the best. In the study of side docking rope, it has been discovered that the mooring effect can be optimized by changing the rope weight and cable holes and that the change of cable holes can considerably influence the effect of side docking. |
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