U.S. natural gas inventories likely saw a sixth consecutive below-normal build last week, further shrinking the storage surplus over the five-year average as a warmer-than-usual September supported demand from the power sector.

Natural gas in underground storage is seen increasing by 53 billion cubic feet to 3,351 Bcf in the week ended Sept. 18, according to the average estimate of 11 analysts, brokers and traders surveyed by The Wall Street Journal. Estimates range from an injection of 35 Bcf to an injection of 72 Bcf.

The expected inventory build compares with a five-year average increase for the week of 76 Bcf, and would reduce the surplus to 95 Bcf from 118 Bcf the week before. It would extend the storage deficit to the year-earlier level to 146 Bcf from 122 Bcf the previous week.

The U.S. Energy Information Administration is scheduled to report weekly natural gas storage on Thursday at 10:30 a.m. EDT.