The Energy Information Administration (EIA) began releasing weekly estimates of natural gas in underground storage for the United States on May 9, 2002. The estimates are posted on the EIA Web site (look for the "Weekly Natural Gas Storage" link) between 10:30 and 10:40 a.m. every Thursday, and include data for the lower 48 states and three regions: East, West, and Producing. The Web site includes a link to a spreadsheet of weekly and monthly storage estimates. The storage estimates will also be part of Natural Gas Weekly Update, a weekly summary of recent market events, released at 2:00 p.m. each Thursday.

Weekly estimates of working gas in storage were first provided by the American Gas Association (AGA) in 1994. In October 2001, the AGA announced that it would discontinue its survey due to resource considerations. AGA's last report appeared on May 1, 2002. The following week, EIA released its first estimates (shown in the table below).

Working Gas in Underground Storage Week Ending May 3, 2002 (Billion Cubic Feet, Except as Noted)
Regiona	Current Week	Prior Week	Net Change	Year Ago
East	736	719	17	540
West	249	237	12	160
Producing	609	599	10	354
Total Lower 48	1,594	1,555	39	1,054
Regiona	5-Year (1997-2001) Average	Current Week's Difference from 5-Year Average (percent)	Survey Sample Coverage (percent)	Estimated Standard Error for Current Week
East	638	15.4	92	24
West	188	32.4	93	17
Producing	424	43.6	91	7
Total Lower 48	1,250	27.5	91	31
aSee Footnotes and Definitions for definitions of regions. Source: Energy Information Administration.

Methodology

EIA has provided information to help users understand how the new survey differs from the previous one, including a description of the survey sample and the calculations used to estimate gas storage (select the "Methodology" link on the Weekly Natural Gas Storage Report Web page).

The EIA survey has a number of similarities with the AGA product. The key differences involve the survey sample and the methodology for estimating regional working gas volumes.

The AGA survey relied on a self-selected sample of AGA member firms and nonmember storage operators who reported on a voluntary basis. The EIA uses a sample that has been statistically selected to be representative of all underground natural gas storage operators, and participation is mandatory. The calculation methods of the two surveys are similar, but some differences in results are expected because of the way data are adjusted under each procedure.

Comparable Results

The EIA began collecting weekly underground storage data on March 18, 2002. The overlap in EIA and AGA operations provided an opportunity to compare estimates directly. An assessment indicates that the two weekly data series yield similar results.

The correlations between the EIA and AGA weekly storage series are quite high. The correlation coefficients are virtually 1.0 for both the total U.S. and the East Region; the lowest correlation value is 0.939 for the Producing Region, with the West Region at 0.967. These very high correlations indicate that the estimates in the EIA and AGA series track closely. The comparisons can be found in the paper "Comparative Assessment of EIA and AGA Weekly Storage Estimates" (select the "EIA-AGA Comparison" link).

The EIA has also generated a set of weekly estimates for the period from 1994 to March 2002, based on monthly storage data the EIA has collected for those years and the weekly variation in the AGA data. This series is used in the historical comparisons presented in the Weekly Natural Gas Storage Report. A description of the database and the methodology used to derive these estimates is found on the EIA Web site (select the "Historical Data" link).

Weekly Natural Gas Storage Report is available only via the Internet.

If you are having technical problems with this website, please contact the EIA Webmaster at wmaster@eia.doe.gov or call 202-586-8959. For general information about energy, contact the National Energy Information Center at 202-586-8800 or infoctr@eia.doe.gov.

Questions about the report's content should be directed to:

Bill Trapmann, Office of Oil and Gas

william.trapmann@eia.doe.gov

Phone: (202) 586-6408

URL: http://www.eia.doe.gov/emeu/plugs/plweekng.html
File last modified: May 23, 2002