The incident happened while crews were preparing to move the rig to a new site.
Officials say a drill rig collapsed near Belfield in western North Dakota this week but no one was hurt.
Nabors Drilling officials tell The Bismarck Tribune that no fluids spilled when the rig's tall derrick collapsed. The company is looking into what happened.
State Mineral Resources spokeswoman Alison Ritter tells KXMB-TV that the incident happened while crews were preparing to move the rig to a new site.
The Dickinson Press reports that it's unclear whether the collapse happened Tuesday or Wednesday.