||Upper Devonian age in the Michigan Basin, in the US state of Michigan, and extending into Ohio and Indiana.
||39,000 square miles
||7 trillion cubic feet of gas
||60 - 220 feet
||Antrim shale is brownish-black shale that overlies the Traverse Formation. The formation was previously known as the St. Cleric Shale in Michigan, and the Genessee Shale in Indiana. The formation is called the Kettle Point Formation in Ontario, and is the stratigraphic equivalent of the New Albany Shale in the Illinois Basin. It is overlain by the Bedford Shale, and underlain in some areas by the Jordan River Formation, and elsewhere by the Thunder Bay Limestone.
||Although the Antrim Shale has produced gas since the 1940s, the play was not active until the late 1980s. During the 1990s, the Antrim became the most actively drilled shale gas play in the US, with thousands of wells drilled. Original gas content ranges from 40 to 100 standard cubic feet per ton. To date, the shale has produced more than 2.5 TCF from more than 9 thousand wells. Most natural gas production is in Antrim, Crawford, Montmorency, Oscoda and Otsego counties. In 2007, the Antrim gas field produced 136 billion cubic feet of gas, making it the 13th-largest source of natural gas in the United States.
||The shale mainly produces methane (CH4) with minor amounts of CO2.