Research On High-impact Area Identification And Risk Assessment Technology Of Shale Gas Gathering And Transportation Pipeline

The proven reserves of shale gas in China are the first in the world,so it is very important for the large-scale development of shale gas to ensure the safe operation of collecting and transporting pipelines.However,compared with the conventional natural gas gathering and transportation pipeline,the operation pressure attenuation of shale gas gathering pipeline is fast,which leads to the rapid change of the identification results of the high consequence area of shale gas gathering and transportation pipeline with time,and the method of regular high-consequence area review of conventional natural gas gathering and transportation pipeline is less adaptable to this feature.The sediment content of pipeline is high,so that the probability of erosion risk event is much higher than that of conventional natural pipeline,and the failure data of erosion risk event of conventional natural gas pipeline can not be directly applied to shale gas gathering and transportation pipeline.In addition,the change of the operating conditions of shale gas gathering and transportation pipeline makes the failure probability change with time.In order to solve the above problems,this paper formulates an early warning mechanism for the re-identification of high-consequence areas,and forms a high-consequence area identification scheme for shale gas gathering and transportation pipelines.The Bayesian network method is introduced,the erosion and wear law of pipeline is studied by using Fluent software,the correction factor of erosion risk event is worked out,and the failure probability calculation method of shale gas gathering and transportation pipeline is formed.The specific research contents are as follows:(1)According to the relationship between the operating pressure and the potential influence radius of the high consequence area,on the basis of the standard of identification of the high consequence area of the conventional natural gas pipeline,the early warning mechanism of the high consequence area is added,and the identification scheme of the high consequence area of the shale gas gathering and transportation pipeline is formed.According to the change of operation pressure of shale gas gathering and transportation pipeline,the early warning mechanism can automatically give the time of re-recognition in high consequence area,adjust the re-identification period dynamically,avoid the drawbacks of the traditional re-identification method,improve the recognition efficiency,and save the management cost.(2)The failure probability calculation model of shale gas gathering and transportation pipeline is established.According to the operating condition and temperament component characteristics of shale gas gathering and transportation pipeline,the pipeline risk factor system is established,and the basic failure probability of risk event is obtained by using the method of failure database and expert evaluation.Aiming at the problem of erosion and wear caused by sand and water content in shale gas gathering and transportation pipeline,the relationship between erosion wear rate,sandstone particle size,sandstone mass flow and sandstone inlet velocity is obtained by numerical simulation using RNG ?-? model.PDM model and Mixture model with bending pipe as the research object.Based on the law of erosion and wear,the correction factor of erosion event of shale gas gathering pipeline is obtained by combining the proportional relationship between shale gas gathering and transportation pipeline and conventional natural gas gathering and transportation pipeline in sandstone particle size,sandstone mass flow rate and sandstone inlet velocity.The correction factor is used to modify the basic failure data to obtain the probability of the occurrence of erosion risk events in shale gas gathering and transportation pipeline.Finally,Bayesian network algorithm is used to calculate the failure probability of shale gas gathering and transportation pipeline.The calculation model can dynamically adjust the probability of erosion risk events according to the change of operating conditions of shale gas gathering and transportation pipeline,and provide technical support for the calculation and renewal of failure probability of shale gas gathering and transportation pipeline.(3)The failure consequence calculation model of shale gas gathering and transportation pipeline is established.The failure mechanism and consequence type of pipeline are studied,and the event tree of pipeline failure consequence is plotted.Based on the analysis of the leakage process,fire and explosion process of shale gas gathering and transportation pipeline,the leakage model,fire model and explosion model of shale gas gathering and transportation pipeline are established.Three models can be used to calculate the quality of gas leakage after pipeline failure,the range of casualties caused by accidents and the number of casualties,so as to lay a foundation for the risk evaluation of pipelines.(4)The risk evaluation model of shale gas gathering and transportation pipeline is established.According to the relevant standard standards,the failure probability and failure consequences of shale gas gathering pipeline are divided into 5 levels respectively,and the 5x5 Risk Evaluation matrix is established.Using the evaluation matrix,managers can quickly determine the level of risk accidents and whether the risks are acceptable,and provide a basis for the formulation of risk decisions.