SandRidge Energy, Inc., together with its subsidiaries, operates as an independent natural gas and oil company in the United States. The company engages in the exploration, development, and production of oil and gas properties. Its Exploration and Production segment explores for, develops, and produces natural gas and oil reserves with focus on the Mid-Continent and Permian Basin. This segment also operates leasehold positions in the West Texas Overthrust (WTO), Gulf Coast, and Gulf of Mexico. The company’s Drilling and Oil Field Services segment is involved in the contract drilling of oil and natural gas wells primarily in the west Texas region. This segment also offers oil field services, including providing pulling units, trucking, rental tools, location, and road construction and roustabout services. Its Midstream Gas Services segment engages in purchasing, gathering, treating, and selling natural gas in west Texas. As of December 31, 2011, its estimated proved reserves were 470.6 million barrels of oil equivalent, of which approximately 52% were oil. The company also had interests in 5,043 gross producing wells, as well as in approximately 2,695,000 gross acres under lease. In addition, it had 21 rigs drilling in the Mid-Continent and 15 rigs drilling in the Permian Basin. SandRidge Energy, Inc. is headquartered in Oklahoma City, Oklahoma.