The drawdown of storage in the producing region was likely due to the shut-in of some Gulf of Mexico wells as Isaac meandered by.
From the Energy Information Administration:
Released: September 6, 2012 at 10:30 a.m. (eastern time) for the Week Ending August 31, 2012.
Next Release: September 13, 2012
Working gas in storage was 3,402 Bcf as of Friday, August 31, 2012, according to EIA estimates. This represents a net increase of 28 Bcf from the previous week. Stocks were 395 Bcf higher than last year at this time and 329 Bcf above the 5-year average of 3,073 Bcf. In the East Region, stocks were 93 Bcf above the 5-year average following net injections of 34 Bcf. Stocks in the Producing Region were 174 Bcf above the 5-year average of 943 Bcf after a net withdrawal of 7 Bcf. Stocks in the West Region were 61 Bcf above the 5-year average after a net addition of 1 Bcf. At 3,402 Bcf, total working gas is above the 5-year historical range.
Working gas stocks in the Producing Region, for the week ending August 31, 2012, totaled 1,117 Bcf, with 221 Bcf in salt cavern facilities and 897 Bcf in nonsalt cavern facilities. Working gas stocks decreased 6 Bcf in the salt cavern facilities and remained at the previous week's level in the nonsalt cavern facilities since August 24. An historical series of the salt and nonsalt subtotals of the Producing Region is available for download at: wngsr_producing_region_salt.xls.