EIA’s Weekly Underground EIA’s Weekly Underground Natural Gas Storage ProgramNatural Gas Storage Program
Federal Energy Regulatory Commission
Technical ConferenceSeptember 28, 2004
Elizabeth Campbell
Energy Information Administration (EIA)
www.eia.doe.gov
Overview of PresentationOverview of Presentation
• Survey respondents and sample
• Survey content
• Collection methods
• Estimation
• Release of estimates
EIA Underground Natural Gas Storage EIA Underground Natural Gas Storage Surveys—Weekly and MonthlySurveys—Weekly and Monthly
SurveyNumber of
RespondentsNumber of Fields
Volume Coverage
Weekly, EIA-912
56 29291-96% by
region
Monthly, EIA-191 120 395 100%
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 It may or may not be completely withdrawn during any particular withdrawal season. Conditions permitting, volumes may be withdrawn and reinjected more than once during any season.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 permanentinventory 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.
Weekly Storage Report RegionsWest Region
East Region
Depleted Fields
Salt Caverns
Aquifers
Producing Region
Source: Energy Information Administration
Overview of OperationsOverview 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
Revision Policy for RespondentsRevision 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
Revision Policy for the EIA Weekly Revision Policy for the EIA Weekly Natural Gas Storage Report (WNGSR)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.
Estimation FormulaEstimation 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
KwwgwwgAYmn
11
*
Weekly Natural Gas Storage ReportWeekly Natural Gas Storage Report
Weekly Natural Gas Storage ReportWeekly Natural Gas Storage Report
www.eia.doe.gov