One of the chief objections of those who oppose drilling for natural gas in the Marcellus Shale is the amount of water used in drilling—an average of 3-4 million gallons per well. Environmentalists raise the alarm of sourcing the water from rivers and streams, and the disposal of what’s left over.
Here’s how the numbers break down: It takes between 100,000 and 300,000 gallons of water during the drilling process itself, and another 3-4 million gallons of water gets mixed with sand and chemicals and pumped in under pressure to fracture the shale, releasing the gas. Anywhere from 10 to 50 percent of the water comes back out—something called “flowback.”
Drilling companies are no less concerned than environmentalists about where to find water for fracking, and what to do with it after fracking, in no small part because of the economics involved. Drillers now recycle wastewater or “flowback” more than ever—approaching 100 percent.
Dave Yoxtheimer, hydrogeologist with Penn State University’s Marcellus Center for Outreach and Research said:
“The majority of companies are working toward reusing 100 percent of their flowback water for several reasons. Environmentally it makes sense, and economically it makes more sense, even though they have to treat some fairly significant dissolved solids.”*
Kelvin Gregory, assistant professor of civil and environmental engineering at Carnegie Mellon University, said this about three of the biggest Marcellus Shale drillers in PA:
Range Resources…recycled 80 percent of its wastewater in 2009, at least 90 percent in 2010, and has set a goal of 100 percent for 2011. Chesapeake Energy and Atlas Energy, other big drilling operators in the state, also are moving in that direction.*
Mr. Gregory said some drillers are even looking at using water from abandoned coal mines.
Drillers are not only using less fresh water in their drilling operations—they’re also using fewer chemicals as well.
“Chemicals cost money,” Mr. Yoxtheimer said. “The less the companies can use without compromising production, the more it would add to their bottom line.”
Range Resources has reduced both the number and amount of chemicals it uses for fracking. The chemical parts of the fracking fluid dropped from one-half of 1 percent to approximately one-tenth of 1 percent.
“In Pennsylvania, you can frack with just about anything,” Mr. Gregory said. “Of the 100 or so chemicals available, they were adding just 10 or 20. Now it’s down to just four or five.”*
*Pittsburg Post-Gazette (Mar 1) – Gas drillers recycling more water, using fewer chemicals