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Enron Mail |
--------- 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
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