Trace gas Trace gas The most abundant gases in the atmosphere are nitrogen (78.1%), oxygen (20.9%), and argon (0.934%). Combined, oxygen, argon, and nitrogen make up 99.934% of the gases in the atmosphere (not including water vapor). The other gases that are not part of the 99.934% of the atmosphere are called trace gases. The abundance of a trace gas can range from a few parts per trillion (ppt) by volume to several hundred parts per million by volume (ppmv). When a trace gas is added into the atmosphere, that process is called a "source". There are two possible types of sources
Shale gas in the United States a Haynesville Shale gas well. Haynesville shale wells have also been drilled in northeast Texas, where it is also known as the Bossier Shale. From 2008 through 2010 Encana accumulated a "large land position" (250,000 net acres) at an "average $150/acre" in the Collingwood Utica shale gas play in Michigan's Middle Ordovician Collingwood formation. Natural gas is produced from the Collingwood shale and the overlying Utica shale. The Michigan public land auction took place in early May 2010 in one of "America's most promising oil and gas plays". The Devonian-Mississippian New Albany Shale produces gas in the southeast Illinois Basin