The Research Of Subsea Pipeline Oii Spill Risk Assessment System

Pipeline risk assessment technology has gone through the process from qualitative risk assessment method to quantitative risk assessment since born in 1970s. It has achieved a certain success by using pipeline risk assessment in on shore pipelines. However, the application of pipeleine risk assessment in offshore pipelines is still quite limited. Based on the successful experience of pipeline risk assessment overseas, combining the actual operational state of pipeline and environmental conditions in our country, a set of subsea pipeline oil spill risk assessment method was built in this thesis.First of all, hazard identification was conducted. Then fault tree analysis of subsea pipeline oil spill was done. With the basis of FTA, the subsea pipeline oil spill risk assessment system was built by applying the multi-level fuzzy comprehensive evaluation method.(1) The probability index system of subsea pipeline oil spill employed corrosion, third party damage, natural force, fatigue, human error as the first hieratchy indexes. The second, third hieratchy indexes were then formed. The consequence index system of subsea pipeline oil spill took the harm of products and the consequence control as the first level indexes. And then formed the second, third hieratchies.(2) The weight of ench index was obtained by using the method of analytic hieratchy process. Expert opinions were adopted to get the fuzzy relation matrix. The final results are two grades between 0 to 100 both probability and consequence by applying the multi-level fuzzy integrative evaluation method. The higher the grades are, the higher the risk is. The risk matris is used to decide if the risk is acceptable.(3) The oil spill quantity in oil pipeline, gas pipeline and oil and gas pipeline has been researched. In order to simultaneously consider the five sources of risk in the consequence index system, the idea of synthetical oil spill quantity was proposed.(4) A preliminary study of pipeline oil spill probability under corrosion was conducted on pipeline quantitative assessment. The depth of inner corrosion was simulated by SwRI model while the length of inner corrosion was treated as a variable obeying Weibull distribution. Both the depth and the length of external corrosion were treated as variables obeying Weibull distribution. Different burst pressure model were used in calculating the oil spill probability.