PureWest Energy LLC operates oil and gas fields with assets in Wyoming. Ultra Petroleum was incorporated in 1979 in British Columbia. Jerry Albertus joined the company in 1996, and the company acquired significant mineral rights in the Green River basin, and it listed on the American stock exchange in 2001. The company filed for bankruptcy in 2016 and emerged from restructuring in 2017. In September 2019, the company emerged from Chapter 11 bankruptcy as UP Energy and was then renamed PureWest in May 2021.