Sour crudes typically trade for less than their sweet counterparts because of their high sulfur content, which requires more processing at refineries. Wyoming sours are also heavier, making them more costly to transport, and are further from the market, factors that also hamper their prices.

Wyoming general sour ended Tuesday at $9 a barrel while medium and heavy sour finished the day at $11.85 and $10.85 a barrel, respectively. Wyoming sweet is fairing slightly better at $18.21 a barrel.

In an attempt to cut costs, sour producers have elected to close some wells that were in need of repairs. Wells not forecast to be economical at present prices have also been shut-in, producers said.

Citation closed 51 wells in 2015, according to a Star-Tribune review of state well records. That was up from 36 in 2014 and 10 the year prior. Citation is hardly alone. Marathon Oil closed 60 wells last year compared to 25 the year prior. Breitburn Energy shut-in 46 wells in 2015 from 16. Vanguard increased its numbers of closures from four in 2014 to 19 last year. The closures do not mean production is permanently halted. The pumps could be turned on again if prices improved. But for that to happen prices would have to be “substantially higher,” Christofferson said.