EIA Natural Gas Stocks Change

The Weekly Natural Gas Storage Report, or WNGSR, is published by the EIA, the independent statistics agency of the U.S. Department of Energy. It estimates working gas, gas available for withdrawal, held in underground storage in the Lower 48 states, excluding Alaska and Hawaii. It excludes base gas, weekly production, consumption, imports and exports, and the Henry Hub price. Stocks and weekly net change come in billion cubic feet (Bcf).

They rest on a weekly Form EIA-912 sample of about 80 to 85 reporters typically covering at least 90% in each stratum. There is no seasonal adjustment; EIA gives context through year-ago values and 5-year averages.

Stocks are measured as of 9:00 AM Central Time each Friday and reported to EIA by 5:00 PM Eastern Time the next Monday. If Monday is a federal holiday, the deadline moves to Tuesday, and EIA checks the data from Monday to Wednesday. EIA publishes year-round at 10:30 AM Eastern Time each Thursday, about 6 days later, except in holiday weeks.

Each release shows regional and Lower 48 stocks, net change, implied flow, year-ago and 5-year comparisons, a summary, a chart, and sampling errors. Respondents are asked to report revisions over 500 million cubic feet, and EIA publishes revisions at 4 Bcf. An unscheduled release comes at 2:00 PM Eastern after notice between 1:00 and 1:10 PM when corrections reach 10 Bcf.

Weekly change reflects injections, withdrawals, and accounting adjustments across six regions.

• East: working gas in eastern consuming states, drawn down by winter heating demand.
• Midwest: working gas in midwestern consuming states, also driven by winter heating demand.
• Mountain: smaller stocks in western interior producing and consuming states.
• Pacific: small western stocks covered by a full census of all eight operators with no sampling error.
• South Central Salt: fast cycling storage in Gulf Coast salt caverns used to balance production and LNG.
• South Central Nonsalt: slower seasonal storage in depleted fields and aquifers in the same producing states.

The week ending January 5, 2018 withdrew a record 359 Bcf, beating the prior 288 Bcf record from 2014 by 25%. The 2-week withdrawal reached 565 Bcf in extreme cold, beating the prior 510 Bcf record from January 1 to 15, 2010. Stocks fell to 2,767 Bcf, 12% below year-ago levels and 13% below the 2013 to 2017 average, as use surged and freezes cut output. Northeast spot prices spiked, with Algonquin Citygate at $82.75 and Transco Zone 6 NY at $140.52 per MMBtu.

1. 12-month average: For each company, average monthly stocks over the latest 12 months from the EIA-191 census.
2. Weekly ratio: Divide each reporter current stocks by its own 12-month average.
3. Regional medians: Take the median of seasonal factors and weekly ratios across reporters in each region.
4. Nonreporter estimate: Scale each missing company average by the regional ratio, adjusted for its own seasonality. An average of 50 Bcf with a regional ratio of 0.925 and a factor of 0.5 gives about 48.1 Bcf.
5. Total and net change: Add reported and estimated volumes by region, round each region independently, then subtract the prior week estimate. For example, 328 Bcf minus 320 Bcf gives a net injection of 8 Bcf. An 8 Bcf change holding 5 Bcf of reclassification gives 3 Bcf of implied flow.
6. Implied flow and history: Subtract reclassifications of 4 Bcf or more to get implied flow, the flow without accounting shifts. Build 5-year averages and year-ago values by daily interpolation between Friday readings. A 50 Bcf draw with error 2.2 gives a 90% margin near 4 Bcf, or -54 to -46 Bcf.