Water use in Barnett Shale gas wells
All forms of energy require water, and natural gas is the most efficient option, using only 1 to 3 gallons of water per MMBTU (million British thermal units). This includes all forms of natural gas production from conventional onshore wells, offshore wells, and natural gas from shales, including the Barnett Shale.
With the drought conditions that we had in Texas in 2011, there have been questions about the water that is used in the hydraulic fracturing process.
As it turns out, the water used to hydraulically fracture shales does its job very efficiently by unlocking significant amounts of natural gas for every gallon of water used. The high production volume from deep shale natural gas wells sets them apart from other natural gas wells, including coal bed methane and conventional wells. From a water perspective, it is this high production that helps offset the larger volumes of water used in the hydraulic fracturing process.
The numbers explain the situation well. A typical Barnett Shale natural gas well will produce roughly 2 million to 4 million MMBTUs (million British thermal units) over its lifetime; consequently, it will use between 1.5 and 2.5 gallons of water per MMBTU.
Although some of the produced water is recycled, the majority goes into deep disposal wells. However, in less than a year, a Barnett Shale gas well will produce enough natural gas, that when burned, will generate more water vapor than was used to drill and produce the well, therefore making it the most efficient use of water among energy resources, excluding wind and solar, which are not significant power sources (GWPC, “Deep Shale Natural Gas and Water Use.” 2010).
The bottom line: all of our energy needs require water, so it makes sense to promote and use the most efficient user of water—natural gas. Coupled with the fact that natural gas is clean, abundant and domestic, it could be the fuel of choice moving forward, whether water is plentiful or under recommended restriction.