Performance prediction of underground gas storage in salt caverns

Underground gas storage is a common activity in countries with major transport and distribution gas pipeline infrastructures, which allows to efficiently resolve demand seasonality problems. Subsurface caverns in salt formations are being increasingly used for storage of natural gas. In this study, a real salt cavern having the potential for being an underground gas storage unit was evaluated. A model of the salt cavern was constructed within the gas simulator established for the purposes of this study. The simulator IMEX that is CMG's (Computer Modelling Group) new generation adaptive implicit explicit simulator was used to investigate the production and injection performance and depth of caverns. Grid description of the salt cavern was used. Theoretically a cylindrical prism was chosen for modelling of the salt cavern. The production and injection well was set in the middle of the salt cavern. The place of the salt cavern was chosen in Tuz Golu field in central Turkey. The data of this field and old wells were reviewed. In calculations, the actual data of the field was used. The data includes formation and salt characteristics (densities, limiting stress of salt, temperature). The selection of the cavern depth is one of the most critical points. The depth determines the cavern pressure. Six depth intervals were chosen for the top level of cavern. From various selected depths, the depth of the cavern was optimized and found as 1,275 m. It was seen that as depth increased maximum cavern pressure increased but also allowable minimum cavern pressure increased. For various flow rates, maximum numbers of injection and production days were obtained. At the end of simultaneous optimum production flow rate was found as 17.66 MMSCF/D, and optimum injection flow rate was found as 14.13 MMSCF/D for the optimum cavern depth.