--------- Inline attachment follows ---------

From:  <mguido@Hess.com>
Date: Thursday, June 20, 2002 4:09:52 GMT
Subject: 


Subject: FW: Revisions to EIA Monthly and Weekly Gas Storage Estimates 




Listed below is the EIA explanation that was released at the time of week's
storage data.

Revisions to EIA Monthly and Weekly Gas Storage Estimates
Measures of working gas, base gas, and total gas in storage for March 2002
based on the EIA monthly survey of all gas storage operators were released
on June 19, 2002, along with revisions for the months of November 2001
through February 2002 in the Natural Gas Monthly.

The March monthly data provided the first opportunity since the beginning of
the EIA weekly natural gas storage survey to compare the reports of monthly
and weekly surveys for weekly sample members for a comparable report period
(the end of March for the monthly survey and the weekly surveys for the
Fridays preceding and following the end of March). As a result of the
cross-survey data comparison, a number of questions were directed to the
respective respondent contacts. Many of these questions have been resolved,
resulting in new or revised submissions of data for either the monthly or
weekly surveys. Although most respondents have been prompt, a few questions
remain. Reasons for revisions in monthly and weekly data include resolution
of:
? Companies' reporting responsibilities for their field operations
? Questions about how joint operations of a field should be reported
? Questions about whether gas should be identified as base or working gas
Revisions to Derived Weekly Estimates. The recent revisions to EIA monthly
data for November 2001 through February 2002 required reestimation of the
derived estimates for the weeks in that period to conform to the methodology
for the derived estimates. The derived estimates (which are calculated to
provide comparison to prior years) are weekly stock estimates calibrated to
the EIA monthly surveys. (A description of the methodology is available at
http://tonto.eia.doe.gov/oog/info/ngs/history.html.) Changes to the derived
estimates will occur whenever the EIA monthly volumes for periods prior to
March 2002 are revised. Eventually, weekly estimates based on the EIA weekly
survey (Form EIA-912) will be available for all prior period comparisons. 
The largest revision to any derived weekly stock estimate for the weeks
during November 2001-February 2002 is an increase of 50 Bcf, or 1.6 percent,
for the November 30, 2001, estimate. This adjustment is composed of
increases of 31 Bcf in the Consuming East Region and 19 Bcf in the Producing
Region. These changes represent 1.6 percent and 2.1 percent of inventories
in the respective regions. Revisions to total stocks and those stocks in the
Consuming East Region and the Producing Region in any other week are 1.6
percent or less. However, revisions to the data for the Consuming West
Region have a higher relative impact, partly owing to the smaller working
gas volumes for that region. 
Revisions to Weekly Data from the EIA-912 Survey. On June 20, 2002, the
weekly working gas stock estimates from the EIA-912 survey were revised for
all weeks from March 15, 2002, through June 7, 2002. These changes represent
an increase of 30 Bcf on average for all weeks from March 15 to June 7. As a
result of the revisions, inventories in all three regions are higher. The
average change for U.S. total inventories is less than 2 percent. The
largest average revision occurred in the East Region, where the stocks
increased by 3.2 percent. Revisions occurred in inventory levels for all
weeks and consequently had little effect on the net change estimates, which
reflect the movement in inventory estimates for two consecutive weeks. The
revisions to weekly estimates were the result of revised data reports and
the use of updated ratios for expansion of the sample reports. The use of
ratios based on monthly surveys is explained in the Methodolog