Occidental Petroleum Corp, Diamondback Energy Inc and a host of smaller Permian-focused U.S. shale producers on Monday forecast lower oil output in the first quarter, giving the first indications of the hit to the industry caused by last week’s winter storm. Areas of Texas not used to the cold were hit by sub-zero temperatures and record snow falls last week. While natural gas producers benefited from cold weather forcing closure of wells, shale oil drillers stood on the losing side of the trade as frozen pipes and power supply interruptions were expected to slow an output recovery, operators said. Shale oil producers could take at least two weeks to restart the more than 2 million barrels per day (bpd) of crude output lost during the cold snap and some production may never return because of the cost of restarting marginal wells, analysts said. ADVERTISEMENT Diamondback estimated it lost four to five days worth of total production from its current-quarter earnings, sending its shares down nearly 4% to $65.95 in late trading. Oil shares had rallied during the day on higher oil prices. Occidental forecast the storm would cut about 25,000 barrels of oil and gas from its first-quarter production. Its shares also reversed course after the bell and were down about 2%. Among others posting production knocks: Cimarex Energy Co forecast a hit of up to 7% to first-quarter volume. Laredo Petroleum Inc also said well shut-ins and completion delays will reduce first-quarter total oil and gas production by about 8,000 bpd. Its production is starting to return to pre-storm levels, officials said. Shale’s outlook was challenged even before the recent storm and “will remain difficult”, said Peter McNally, global sector lead for industrials, materials and energy at research firm Third Bridge. Diamondback forecast full-year oil and gas production of between 308,000 and 325,000 bpd, higher than the 300,300 bpd it produced in 2020 when production was curbed because of pandemic-driven plunges in crude prices. Occidental, which cut production guidance to reduce expenses, forecast full year oil and gas output to drop from 2020’s 1.35 million bpd to an expected 1.14 million bpd in 2021, as it sells assets to pay off debt it took on to acquire Anadarko Petroleum Corp in 2019.