U.S. natural-gas futures gained roughly 2.2% on Thursday after the Energy Information Administration reported a far smaller-than-expected increase in inventories. Underground storage rose by 13 billion cubic feet in the week ended Aug. 15, well below the 18-Bcf analyst consensus and the prior week’s 56-Bcf injection. Total working gas in storage reached 3,199 Bcf, according to the EIA. That level is 95 Bcf lower than a year ago but remains 174 Bcf above the five-year average, keeping inventories within the historical range for this point in the injection season.