Shale gas is found in shale “plays,” which are shale formations containing significant accumulations of natural gas and which share similar geologic and geographic properties. A decade of production has come from the Barnett Shale play in Texas. Experience and information gained from developing the Barnett Shale have improved the efficiency of shale gas development around the country. Another important play is the Marcellus Shale in the eastern United States. Geophysicists and geologists identify suitable well locations in areas with potential for economical gas production by using surface and subsurface geology techniques and seismic techniques to generated maps of the subsurface. See animated maps of production growth in the Barnett Shale and Marcellus Shale plays in Today in Energy articles — July 12, 2011 and May 23, 2012.
