Research On The Method Of Calculating The Probability Of Oil Spills At Sea

Through summarizing the domestic and international oceanic oil spill incidents of the recent years, this thesis classifies all the causes of oil spills into following three types:ship accident that leads to spill; terminal tank farm accident that causes spill; drilling platform and subsea pipeline accident that creates spill. According to the statistics, ship accident is accounted for the largest percentage among all accidents. In contrast, terminal tank farm accident or drilling platform accident and subsea pipeline accident takes small proportion. Nevertheless, they should be taken seriously because of their severe consequences. In recent years, many studies within or outside of our country have been carried out for the risk occurrence of oil spill caused by ship accident under the support of basic probability method and logical probability method. However, methods to calculate the frequency of oil spill caused by terminal tank farm accident or by drilling platform and subsea pipeline accident are absent.Therefore, focusing on the fairly comprehensive statistical data for ship accident oil spills, this paper will apply the basic probability method to the risk assessment of the oil spills caused by the ship accidents in Dandong Port. The results after the calculations indicate that the rate for the operational accident oil spill in amount below 1 ton is about once every 1.24 years; the rate for the average accident oil spill in amount more than 50 tons is about once every 15.58 years. Due to the strong interrelation among incidents led by terminal tank farm accidents or drilling platform accident and subsea pipeline accidents, Fault Tree Analysis (FTA) is used in the risk assessment of the oil spills caused by the accidents on #3 terminal tank farm at south of Dadong District in Dandong Port, resulting at the rate of about once every 129 years for oil spill more than 100 tons. Event Tree Analysis (ETA) is used in the risk assessment of the oil spills caused by the accidents of drilling platforms and subsea pipelines in Tanhai area of Liaohe, resulting at the rate of about once every 356.7 years for oil spill more than 500 tons. The final part of the thesis addresses the prevention and control measures for the three types of oil spill accidents.This thesis studies the applicability of different probability estimation methods and applies each method accordingly to the three types of oil spill accidents to draw the results that can provide some simple and scientific measures for occurrence of oil spill.