1. EIA’s Weekly Underground Natural Gas Storage Program Federal Energy Regulatory Commission Technical Conference September 28, 2004 Elizabeth Campbell Energy Information Administration (EIA) Elizabeth.Campbell@eia.doe.gov www.eia.doe.gov

2. Overview of Presentation Survey respondents and sample Survey content Collection methods Estimation Release of estimates

3. EIA Underground Natural Gas Storage Surveys—Weekly and Monthly Survey Number of Respondents Number of Fields Volume Coverage Weekly, EIA- 912 56292 91-96% by region Monthly, EIA-191 120395100%

4. Working Gas: Working Gas: The volume of gas in the reservoir that is in addition to the base gas. It may or may not be completely withdrawn during any particular withdrawal season. Conditions permitting, volumes may be withdrawn and reinjected more than once during any season. Base Gas: Base Gas: The volume of gas needed as a permanent inventory to maintain adequate reservoir pressures and deliverability rates throughout the withdrawal season. Terms for Natural Gas in Storage Source: EIA-912 Weekly Underground Natural Gas Storage Report Instructions.

5. Weekly Storage Report Regions West Region East Region Depleted Fields Salt Caverns Aquifers Producing Region Source: Energy Information Administration

7. Overview of Operations Working gas volumes as of 9:00 a.m. on Friday; due by COB Monday Respondents report company volumes at a regional level; estimates allowed EIA edits data; quality comparisons provided to monthly surveys EIA provides secure work areas for processing

8. Revision Policy for Respondents Revised data should be submitted whenever the measure of working gas for the prior week in any region has been revised by 500 million cubic feet or more. Respondents are requested to submit a revised form when that happens

9. Revision Policy for the EIA Weekly Natural Gas Storage Report (WNGSR) Revisions shall be disseminated in the WNGSR according to the established schedule and shall occur when the effect of reported changes is at least seven billion cubic feet at either a regional or national level. If a revision is made, changes to all regions shall be recorded. Changes shall only lead to a published revision when it exceeds the seven billion cubic feet threshold. Revisions shall not be disseminated on an unscheduled basis. EIA will include revisions in the estimates as part of the next release of the Weekly Natural Gas Storage Report on its web site.

10. Estimation Formula where: Y = Estimate of working gas for a region A = Estimation factor in the given region wwg = Weekly working gas in storage for sample operators in region for the collection week n = Number of operators in the estimation companies group m = Number of operators in the base group; hence the total number of operators in the sample group equals n + m K = Volumes of working gas that exhibited little or no variation at a company level, for companies in the nonsampled group

11. Weekly Natural Gas Storage Report

13. www.eia.doe.gov