Study On Risk Analysis And Evaluation For The Salt Cavern Storage

With the increasingly serious problem of energy shortage in the world, the strategic reserve of energy has been performed in our country. Based on the good characters of creep property, low permeability and self-healing of damage, Salt rock has been widely used in energy storage of oil and gas. Nowadays, most research are concerned on the mechanical properties of salt rock at home and abroad, but the studies about risk analysis on the salt cavern storage are still few. Especially compared with the thick salt dome of abroad, the salt bed has the characters of small thickness, multi-laminated, and shallow depth in our country. The hidden troubles have been brought to the safe operation of the salt cavern storage. So in order to explore the risk mechanism of salt cavern, in the background of salt rock gas storage named JINTAN in JiangSu province under the support of National Key Basic Development Plan(973 subject)-《Risk assessment of catastrophe and regulation mechanism for soil and gas storage in the operation process》, the risk analysis and evaluation of the salt cavern storage has been carried out in the life cycle, which will be an effective guidance for the risk elusion of salt cavern storage during the operational period. The content and innovative points included in the article are presented as follows:In the first place, the risk definition of the salt cavern storage is made clear. The risk factors of the salt cavern storage in its life cycle are identified; especially the main risk factors during the planning period, design period, construction period and operational period are gained.In the second place, Fault tree analysis (FTA) is applied to establishing the analytical models on cavern failure, surface subsidence and storage leakage during the operational period. The risk factors during the operational period are sorted on their influence level, and the 17 main risk factors influencing the safety of the salt cavern storage seriously are got. In the third place, expert investigation is carried out to get the influence level statistics data of the risk factors of the salt cavern storage during the operational period. Fuzzy comprehensive evaluation (FCE) is applied to obtain the degree classification of the risk factors on cavern failure, surface subsidence and storage leakage.In the fourth place, based on the criteria of the structural failure probability, the failure grade standards of salt cavern storage are established. And according to the cases, that the cavern diameter ratio is changed and the inside pressure of the salt cavern is different, the failure standards of the cavern are plotted out.Last but not least, the basic requirements of risk control of the salt cavern storage during the operational period are proposed. The measures of risk control of cavern failure, surface subsidence and storage leakage are also proposed.