Quantitative Risk Assessment Method And Its Application For Long Distance Natural Gas Pipeline

In order to prevent and reduce the occurrence of accidents,quantitative risk assessment method is widely used in the oil and gas pipeline industry,mainly including risk identification,accident probability calculation,accident consequence assessment,risk quantification and risk assessment.Accident probability calculation,accident consequence evaluation and risk acceptance criterion are three important parts of quantitative risk evaluation.However,there are many limitations in the existing research,such as the fact that the accident probability calculation is not combined with the actual situation,the accident consequence evaluation does not consider the intangible loss,the risk acceptable standard does not include the reputation loss risk acceptable standard and so on.In order to solve the above problems,this paper,by means of theoretical analysis and practical investigation,takes into account that the consequences of natural gas pipeline accidents are often greater than the consequences of oil pipeline accidents,and carries out quantitative risk assessment method and its application for natural gas pipeline.The main contents are as follows:Firstly,according to the typical pipeline failure database,the statistical characteristics of the basic failure probability data of long distance natural gas pipeline are analyzed.Based on the reality of our country,the failure probability correction model of long distance natural gas pipeline is put forward.On the basis of considering the ignition source type and ignition probability,the calculation model of accident probability of long distance natural gas pipeline is established.Secondly,the cases of pipeline accidents are analyzed.The types of accident consequences include jet fire,flash fire and steam cloud explosion.Accident losses are divided into tangible losses and intangible losses.This paper puts forward a procedure for evaluating the consequences of natural gas pipeline accidents:selecting representative calculation material,selecting typical pore size,determining the type of leakage,calculating the leakage rate and estimating the total amount of the leakage material,identifying the consequences of the accident,using the consequences calculation model,determining the impact scope of the accident and calculating the pipeline accident loss.Thirdly,the connotation of natural gas pipeline accident risk is studied,which includes human safety and health loss risk,economic loss risk,environmental loss risk and reputation loss risk.A quantitative risk evaluation model is constructed from three aspects:accident probability calculation,accident consequence evaluation and risk acceptance criteria.According to the ALARP principle,the acceptable standards of human safety and health loss risk,economic loss risk,environmental loss risk and reputation loss risk are determined respectively,and then the acceptable standards of risks of natural gas long-distance pipelines are proposed.Finally,the method and model proposed in this paper are applied to a specific project to verify its scientificity and rationality.The innovation of this paper is as follows:(1)according to the historical failure data and the actual situation of natural gas long distance pipeline,the correction method of accident probability calculation is proposed;(2)multiple losses caused by accidents are considered in the calculation of accident consequences,and the evaluation of accident consequences is more authentic;(3)the acceptable standard of pipeline risk includes the acceptable standard of human safety and health loss risk,economic loss risk,environmental loss risk and reputation loss risk,which makes the risk quantification more comprehensive.In this paper,the existing quantitative risk assessment method of long distance natural gas pipeline is improved,which can provide reference and decision basis for safety risk management of pipeline enterprises.