As with many of the booming oil and gas regions in the United States, the Marcellus basin was known to have gas deposits for decades before they were ever considered viable. Once the first horizontal well began producing in 2005, however, a boom was ignited in Pennsylvania.
In a few short years, the Marcellus Basin has become the largest natural gas field in the country, providing 20% of our total natural gas output. Thanks to the successes provided by hydraulic fracturing techniques, the estimate of technically recoverable gas has increased from 1.9 trillion cubic feet, to the latest EIA estimate of 143.8 trillion cubic feet, with some outside estimates even going as high as 480 trillion cubic feet.