Abstract

Underground reservoirs (depleted gas reservoirs, aquifer reservoirs and salt cavern reservoirs ) are most important type of underground natural gas storage. Characteristics of underground storage facilities need to be defined and measured: Total gas storage capacity, Total gas in storage, Base gas (also referred to as cushion gas), Working gas capacity, Working gas, Physically unrecoverable gas, Cycling rate, Deliverability, and Injection capacity (or rate). Underground natural gas storage is relied upon to smooth the natural gas supply to feed high peak gas demands. The key to smoothing the supply is to be able to store during periods of low demand large quantities of gas that can be produced quickly to meet peak demand. Surplus natural gas (methane) delivered by pipelines to consuming areas is injected into large underground reservoirs. The most important characteristic of an underground storage reservoir is its capability to hold natural gas for future delivery.