PDC Energy, Inc., formerly Petroleum Development Corporation, doing business as PDC Energy, is a domestic independent exploration and production company, which acquires, develops, explores, and produces natural gas, natural gas liquids (NGLs), and crude oil. Its Western Operating Region is focused on development in the Wattenberg Field in Colorado, particularly in the liquid-rich horizontal Niobrara play and on the ongoing development of refractures and recompletions of its Wattenberg wells. In its Eastern Operating Region, it is focused on horizontal development in the Marcellus Shale in northern West Virginia, and initiated exploration and development activity in the Utica Shale play in Ohio. Its segments include Oil and Gas Exploration and Production, and Gas Marketing. In July 2012, it acquired core Wattenberg assets. In September 2012, Miller Energy Resources, Inc. acquired its Tennessee assets.