Rock salt is a globally recognized ideal medium for energy storage.Due to the special characteristics of Chinese rock salt,e.g.,thin depth,high impurity content and containing many insoluble interlayers,the horizontal cavern is more suitable for the underground energy storage in China.In order to ensure the safety of the cavern and to maximize the total storage volume,a new storage form of the horizontal cavern with two wells under constant internal pressure was proposed.The two wells,which were used to inject and extract brine and natural gas respectively,were evenly arranged in a rotating cavern.During natural gas extraction/injection,brine was injected into/extracted from the cavern,so that the internal pressure was maintained at its constant maximum level.Based on the actual geological structure and mechanical parameters of the salt rock in Jintan,a numerical model of the new horizontal cavern was established,and then a simulation was carried out with the finite difference software FLAC3D.The feasibility and safety of the storage form were studied from four aspects:stability,tightness,usability and blowout analysis.Besides,the operation of the traditional gas storage was also simulated for comparison.The results showed that,the new storage form could meet all aspects of safety requirements,and its performance was significantly better than that of the traditional gas storage.In addition,the new storage form had some other advantages,such as good economic efficiency,flexibility,strong ability of peak regulation,good ability to cope with blowout,low cost of the unit volume,making full use of salt layer and so on; thus,the new storage form is demonstrated to be quite suitable for China's rock salt.
