The Marcellus Shale is only one of a number of similar gas-bearing shales that are currently under development via horizontal drilling and hydraulic fracturing in the US. Others include the Barnett Shale in Texas and the Haynesville Shale
in Louisiana. Still more are being developed around the world. The amount of water required to hydraulically fracture a well depends upon the rock properties of the particular target formation in question, which can also differ from well to well
within that formation, as conditions are nor uniform throughout a formation. The amount of water required to stimulate (the industry term for cracking the shale through hydraulic fracturing to release the natural gas ) an individual well also
depends heavily upon the length of the laterals (the horizontal portions) of that well. It takes between 300,000 and 500,000 gallons of water to fracture each 500 feet of well bore