Winter storm Fern has slashed U.S. oil and gas production as operators curtailed output amid the big freeze. Over the weekend, the storm led to producers losing up to 2 million barrels per day (bpd) of oil production, or about 15% of total U.S. oil output, according to estimates by analysts and traders cited by Reuters. According to estimates by Energy Aspects, the Permian alone saw production outages of around 1.5 million bpd. However, production is already recovering, and the lost output in the Permian is down to some 700,000 bpd. Output is expected…