Underground natural gas storage fields in the American Gas Association’s (AGA) East region have neared their capacity limits before each winter since 2005. Storage field utilization in the East has ranged between 87% to 92% before November of each year despite changes to market conditions. However, storage capacity utilization varies by region because of differences in weather patterns, types of facilities, pipeline constraints, proximity to supplies, and regulations, according to U.S. EIA.
Storage levels and available capacity for working natural gas, or natural gas that is used for withdrawal, respond to a different set of factors in each region:
The Producing region differs from the East and West regions in that its salt cavern storage facilities require lower volumes of base gas, which is natural gas required to maintain adequate pressure in the facilities. Since the beginning of 2012, base gas has accounted for about 41% of total storage capacity in the Producing region, versus 53% in the East region and 46% in the West region. This difference in the base gas required means that a relatively greater portion of storage capacity in the Producing region can be set aside for working gas. Changes in the Producing region’s pre-winter working gas inventories have driven changes to overall inventories in the Lower 48 states.
The Short-Term Energy Outlook projects that U.S. working inventories will reach 3,800 Bcf by the end of October 2013, with April-October injections similar to those in 2008–11, but much higher than in 2012, when October 31 inventories reached a record 3,930 Bcf. Projected inventory levels for October 31, 2013 are lower than those for the same date in 2012 because of increased withdrawals in the Producing region during a colder 2012–13 winter, along with flattening production in 2013.
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Source: EIA, September 4, 2013