The Marcellus Shale is a Middle Devonian-age black, low density, carbonaceous (organic rich) shale that occurs in the subsurface beneath much of Ohio, West Virginia, Pennsylvania and New York. A company called Range Resources is arguably the industry player attributed with starting Marcellus Shale gas play. In 2003 Range drilled a Marcellus well in Washington County, Pennsylvania and found a promising flow of natural gas. They experimented with horizontal drilling and hydraulic fracturing methods, which worked well in the Barnett Shale of Texas, and brought their first Marcellus gas well to production in 2005. In just a few years later, more than 375 gas wells targeting Marcellus had been permitted in Pennsylvania. The presence of an enormous volume of potentially recoverable gas in the eastern United States has great economic significance. This is some of the closest natural gas to the high population areas of New Jersey, New York and New England. This location gives Marcellus gas a distinct advantage in the market place. Currently, through joint development with its partners, Mitsui had secured around 135,000 net leasehold acres, and has participated in approximately 1,100 wells in shale play. After divestment of acreage previously operated by Anadarko, Mitsui currently has 62,000 net acreage and working interests in 750 wells.