Unit Corporation, together with its subsidiaries, operates as an oil and natural gas contract drilling company primarily in the United States. The company operates through three segments: Oil and Natural Gas, Contract Drilling, and Mid-Stream. The Oil and Natural Gas segment explores, develops, acquires, and produces oil and natural gas properties primarily located in Oklahoma and Texas, as well as in Arkansas, Colorado, Kansas, Louisiana, Mississippi, Montana, New Mexico, North Dakota, and Wyoming. As of December 31, 2014, this segment had approximately 177 gross proved undeveloped wells. The Contract Drilling segment is involved in the land contract drilling of onshore oil and natural gas wells for its own account, as well as for a range of other oil and natural gas companies principally in Oklahoma, Texas, Louisiana, Kansas, Wyoming, and North Dakota. As of December 31, 2014, this segment had 75 operating rigs. The Mid-Stream segment buys, sells, gathers, transports, processes, and treats natural gas for third parties and for its own account. This segment operates 3 natural gas treatment plants, 14 processing plants, and 38 gathering systems, as well as approximately 1,525 miles of pipeline in Oklahoma, Texas, Kansas, Pennsylvania, and West Virginia. Unit Corporation was founded in 1963 and is based in Tulsa, Oklahoma.