0927 ET - U.S. natural gas futures are giving back some of the previous session's hefty gains that were largely due to an interruption on a TC Energy pipeline in West Virginia. "It now appears that this outage could prove brief," Ritterbusch & Associates says in a note. "Yesterday's price response to the pipeline outage was likely exacerbated by a continued heavy speculative presence on the short side of this market, where participants have likely been lulled to sleep by what has been a sizable storage cushion across the past summer." Yesterday's EIA report showed the storage surplus shrinking for a sixth consecutive week, and further reductions are likely as heat has lingered across much of the southern U.S., the firm adds. Nymex natural gas is down 4.6% at $3.147/mmBtu.