Effective Modeling and Analysis of Salt-Cavern Natural-Gas Storage

Abstract

Summary A rigorous modeling approach is developed for effective management and inventory analysis of natural-gas storage in underground salt caverns by considering the interactions of storage gas with surface facilities through wells and surrounding salt formations. Computational-fluid-dynamics (CFD) and heat-transfer-modeling approaches are used to simulate the strongly coupled fluid-mechanics and heat-transfer problems involving cavern gas storage. Implementation of effective numerical methods and algorithms successfully generates the wellbore-temperature and -pressure distributions; storage-gas-temperature, -pressure, and -velocity distributions; and temperature and pressure distributions of the gas leaking into the surrounding naturally fractured salt formation. Practical applications are performed concerning typical gas-injection, -storage, and -production scenarios and inventory analyses for both regular- and irregular-shaped caverns. Reversible and irreversible losses of natural gas into surrounding salt formations through natural defects, such as natural fractures, and defects resulting from deformation, ballooning, and aging effects are taken into account. The maximum amounts of gas that can be stored up to the pressure-safety limit of caverns are shown to vary with cavern shapes. Thus, the cavern-gas inventory analysis is not only dependent on temperature, pressure, and total volume of the cavern, but also the cavern shape. Accurate prediction of the natural-gas storage performance and inventories on the basis of the present comprehensive simulation approach can be instrumental in effective management and balancing of the natural-gas supply and demand.