Denver-based Cimarex Energy is an independent exploration and production company with operations throughout the Southern and Central United States, where its focus includes the Permian Basin, the Cana-Woodford Shale, and the Meramec horizon. The firm was created in 2002 when it spun off from Helmerich & Payne and then merged with Key Production. At year-end 2015, Cimarex's proved reserves were 510.2 mmboe, with net production of 164 mboe/d. Natural gas represented 47% of production and 55% of reserves.