Research On Risk Assessment Of Underground Gas Storage In Salt Caverns

As an important means of gas storage and peak regulation,the salt cavern underground gas storage has the characteristics of sudden suddenness,large destructiveness,wide range of impact,and easy secondary disasters.Compared with foreign gas storage,the geological conditions of underground gas storage in salt caverns in China are relatively complex,with thinner salt beds,more interbeds and higher operational risk,and the risk assessment of underground gas storage in salt caves in China is still in the preliminary stage of study.Therefore,the research on the risk assessment of salt cavern underground gas storage is not only the need to ensure the safety of energy reserve and public safety,but also to provide guidance for ensuring the safe operation of salt cavern underground gas storage.This paper aims to realize the risk assessment of salt cavern underground gas storage from two aspects:static(baseline risk assessment)and dynamic(risk development trend prediction),and supplemented by examples.The specific research content of this paper is as follows:(1)Establish the risk assessment system of underground gas storage in salt caves:The structural characteristics of underground gas storage in salt caves are analyzed.The failure concepts and failure forms,baseline risk assessment concepts and risk prediction concepts of underground gas storage in salt caves are defined.The risk assessment units are divided and the risk assessment tasks and methods are defined,and the reasons and purposes of using this method are analyzed.The above content lays the theoretical and methodological basis for the later research and analysis.(2)Analysis of risk factors of underground gas storage in salt caverns:The system theory method is used to establish the cross-causal cascading compound accident causal model of salt cavern gas storage and the risk factors are identified from four aspects:environment,process equipment,management and personnel of salt cavern gas storage.Based on integrated D/I(Decision Making Trial Evaluation Laboratory/Interpretative Structural Model)model and MICMAC(Matriced' Impacts Croises-Multiplication Applied to Classification),the risk factors of gas storage are analyzed,and risk factors are transformed into hierarchical models with good structural relationship,and different factors are analyzed from the perspective of system theory.Based on this method,the software for risk factor analysis of underground gas storage in salt caverns is developed.(3)Assessing the baseline risk of salt cavern underground gas storage:Based on the modified probability and Bayesian network model,the possibility of failure of ground station facilities and underground gas storage facilities in salt cavern gas storage is determined,considering the influence of wind speed,atmospheric stability,humidity and pressure leakage diameter on the failure of the salt cavern gas storage reservoir,the failure consequence analysis based on PHAST is realized,and the baseline risk assessment of personnel,safety equipment,technology,environment and management risk subsystems based on the entropy weight-extension matter-element model is realized.The baseline risk assessment results will serve as the initial input parameters for the risk prediction model,thus laying the foundation for risk development trend prediction.(4)Predicting the risk development trend of salt cavern underground gas storage:The applicability of system dynamics in the risk prediction of salt eaverm underground gas storage is defined,the risk evolution process is analyzed,the time-varying of risk system and the coupling of risk factors of underground gas storage in salt caverns is grasped,by embedding the basic flow-in tree model of each subsystem flow rate,the Vensim software is used to construct a prediction model of the risk development trend of the salt cavern underground gas storage system based on system dynamics,and the dynamic assessment of risk is realized.(5)Realize the risk assessment of M salt cave gas storage:Based on the baseline risk assessment model and risk development trend prediction model established in this paper,the baseline risk assessment(static risk assessment)and r:isk development trend prediction(dynamic risk assessment)of M salt cave underground gas storage are realized.