Bloomberg News is reporting that Ultra Petroleum has filed for bankruptcy. The gas company is based in Houston, but has most of its assets in Wyoming.

In the papers filed in court in Houston, the company lists $1.3-billion in assets and $3.9-billion in debt.

With 159 employees overall, it is the biggest gas company in Wyoming, and has asked the court to allow it to continue its surety bonding program in the state to insure there will be remediation of roads, drill sites and plugging of wells.

Low commodity prices are to blame for the company’s problems, they say.