Study On Analysis And Evaluation To The Long-term Stability Of Salt Rock Gas Storage

Underground gas storages as peak shaving facilities of t he natural gas supply system,not only has the storage amount,good economy,high safety factor and regulation of natural gas usage are not effective means.Salt karst cavity is an ideal storage medium because of its excellent creep characteristics,damage and recovery characteristics.Therefore,salt rock gas storage has become a widely recognized natural gas reserve in the world.The creep of salt rock has an impact on the stability of gas storage,which is not conducive to the safe operation in the life cycle.In this paper,we use a combination of theoretical analysis and numerical simulation method,the stability of gas storage in salt rock research,gas storage in salt rock stability fuzzy comprehensive evaluation model was established,and to predict the life of gas storage in salt rock,specific content is as follows:On the basis of study on creep properties of salt rock,select the important influence factors on gas storage in salt rock stability.Through the numerical simulation method,cavity weeks maximum creep displacement and dissolved cavity volume shrinkage rate as a reference standard for evaluation of gas storage in salt rock stability,the influence law of each factor of gas storage in salt rock stability,customary international of the reference standard,determine the parameters of reasonable range.According to the calculation of gas storage in salt rock stability evaluation criterion and numerical simulation considering gas storage stability influence factors,the establishment of gas storage in salt rock stability evaluation index system and according to the nature of the evaluation index to determine the set of evaluation,application level analysis method,determined the weight of each index,combined with rock salt gas storage stability numerical simulation results,determine rules for the score of each index,constructing appropriate membership functions to calculate the membership degree,and the eventual establishment of gas storage in salt rock stability fuzzy comprehensive evaluation model.According to the gas storage in salt rock stability fuzzy comprehensive evaluation the evaluation set of gas storage in salt rock operating state is divided into five state,respectively is acceptable risk state I,state of mild risk II,moderate risk status III,severe risk state IV,disaster risk state V;ran after the numerical simulation based on the using reliability analysis of gas storage state transition matrix.Finally,absorbing state Markov models and concepts based on the average absorption time in different operating conditions of salt rock gas storage life prediction.