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Underground Gas Storage

Since natural gas is a combustible material, that is odorless, tasteless and colorless, it is commonly stored in gaseous form in underground gas storage areas. Since it a gaseous substance it must be stored under pressure in a variety of containers. There are three types of underground gas storage facilities that can be used to keep the natural gas safe.

The underground gas storage facilities are depleted reservoirs in oil or gas fields, salt cavern formation and aquifers. Liquid gas is never stored in these types of underground gas storage facilities but is stored above ground instead. Each of these types of underground gas storage facilities has unique features and characteristics. Some of the characteristics of these underground gas storage facilities include permeability, retention capability and porosity.

Another factor that is considered when choosing an underground gas storage facility is the economics involved in storing it safely. The economic factors include the time and material costs to prepare the site for underground gas storage and the maintenance cost after it is constructed. The rate of speed that the product can be delivered from the site is also considered. The cycling capability will determine if the underground gas storage facility is suitable for certain applications.

The most widely used facility method for underground gas storage is through the use of depleted natural gas and oil fields. These underground gas storage locations are preferred because they are close to consumption centers. There are many of these depleted oil and gas reservoirs and they are the most wide used form of storage facility. These underground gas storage facilities are easy to convert to storage facility use because they already have gathering systems, existing wells and pipeline connection already in place.

Natural aquifers have also been converted to underground gas storage facilities. These storage areas are very suitable for use when the water bearing rock made of sedimentary rock formation is overlaid with a cap rock. This type of underground gas storage area is very similar to a depleted production field but requires more monitoring of withdrawal performance and injection performance. There may be an enhancement in delivery rates noted by the presence of an active water drive in these underground gas storage areas.

The salt cavern underground gas storage areas provide a very high withdraw rate and injection rating that relates to their active gas capacity. There are relatively low base gas rates found in this type of underground gas storage area. The Gulf Coast states have the largest number of salt cavern underground gas storage formations. This type of underground gas storage area is more costly than any other type of underground gas storage area in use today.

There are other types of underground gas storage facilities that have been experimented with, such as abandoned mines, but the effort failed. There are plans to conduct research on the use of a hard-rock cavern as an underground gas storage facility. To date, there are no underground gas storage facilities planned for storage of natural gas products.