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)

Elizabeth.Campbell@eia.doe.gov

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 It may or may not be completely withdrawn during any particular withdrawal season. Conditions permitting, volumes may be withdrawn and reinjected more than once during any season.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

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Weekly Natural Gas Storage ReportWeekly Natural Gas Storage Report

Weekly Natural Gas Storage ReportWeekly Natural Gas Storage Report

www.eia.doe.gov