Chief Oil & Gas is a company founded in Dallas, Texas in 1994 by Trevor Rees-Jones. Its primary holdings of natural gas were developed in the core areas of the Barnett Shale in Tarrant County, Denton County and Parker County. In 1999, new technology in horizontal drilling and hydraulic fracturing along with rising gas prices made the Barnett Shale, an unconventional resource for natural gas, more economical. Chief rapidly expanded its leasehold position and drilling and production program in the Barnett Shale to become the fields second largest producer there.After selling, in 2006, the majority of its leasehold and production assets to Devon Energy and its pipeline and midstream assets to Crosstex Energy for $2.63 billion, Chief entered the Marcellus Formation gas play in Appalachia, with its primary leasehold position in Pennsylvania, West Virginia and New York. Chief drilled their first Marcellus Shale gas well in Lycoming County, Pennsylvania in Watson Township in the fall of 2007. The company also has a leasehold position in the Utah Thrust Belt in central Utah with development expected to begin in 2009.Quicksilver Resources Inc., a Fort Worth-based company, purchased another portion of Chief’s Barnett Shale holdings in July 2008. Quicksilver purchased natural gas producing properties in Tarrant and Denton counties from several companies including Chief Oil & Gas LLC, Hillwood Oil & Gas LP and Collins and Young LLC for $1.3 billion.In December 2010, Chief entered into an asset purchase and sale agreement to sell certain natural gas properties in the Marcellus Shale to EXCO Holding PA, a subsidiary of EXCO Resources Inc., for approximately $459 million. The sale assets include 15 producing wells, 11 wells waiting on completion and approximately 50,000 net acres located in Lycoming, Sullivan and Columbia counties in Pennsylvania.