Study On Risk Analysis And Emergency Measures Of Submarine Pipeline Leakage Accidents

Submarine pipelines in marine environment are experiencing complicated loads in term of environment, working and incidents, which leads to high failure probability. The repair or replacement of submarine pipeline failure not only affects the normal delivery of oil and gas,but also leads to marine environment pollution or even ecological disaster. Marine oil and gas exploitation depth has extended from shallow water to around 3000 m so that more and more submarine pipelines are being installed in deep seafloor and the corresponding risk increases rapidly. Study on risk analysis and emergency measures of submarine pipeline leakage accidents can improve the level of operation management and accident treatment. This dissertation mainly focuses on the need of offshore oil and gas safe transportation of submarine pipelines, which is a part of the central academy basic research operating expenses special funding supported projects “Methods Studying on Unstable State Evaluation of Submarine Pipelines Under Complicated Conditions” and postgraduate student innovation engineering supported project(CX-1226) “Study on Risk Analysis and Emergency Measures of Submarine Pipeline Leakage Accidents”.This dissertation investigated the databases at home and abroad. The extensive statistics of submarine pipeline leakage accidents in the Gulf of Mexico and domestic sea were completed in this dissertation. By means of mathematical statistics, the cause of the accident, water depth, offshore distance, area distribution and medium have been analyzed. Through establishing a Fish Bone Fig model, this dissertation analyzed the cause of submarine pipeline span deeply. A new method for submarine pipeline fatigue damage assessment has been proposed with consideration that the state of submarine pipeline span varies from embedding, nudity, spanning to re-burying. Based on the measured data of a submarine pipeline span in east China, the fatigue damage of submarine pipeline has been investigated with GM(1, 1) model. By using Visual Basic tools, this dissertation developed a submarine pipeline span risk assessment software. The direct causes of submarine pipeline internal/ external corrosion failure have been analyzed(external corrosion mainly focused on cathodic protection and external pipeline coatings) from the perspective of technology. A Fish Bone Fig model for pipeline corrosion failure has been established, and eventually the essence causes has been obtained. The FLUENT mathematical simulation technology was adopted to establish the simulation model of spilled oil diffusion under water, at the same time the influence of leakage pressure and flow rate on oil spill diffusion range, diffusion path and leakage volume have been studied. In addition, in the point view of the FLUENT simulation model for submarine pipeline negative pressure protection,the three factors, i.e. the block valves delay, start time of pressure relief and duration of the pressure relief effect on oil spill volume have been calculated, the effective measures to reduce the oil spill consequences have been proposed in this dissertation.