Gas drilling used 4 percent of water in Barnett Shale in 2011, UT study says

02/12/2014 5:56 PM

02/12/2014 11:45 PM

Drilling and hydraulic fracturing in the Barnett Shale used about 8.5 billion gallons in 2011, or about 4 percent of all water used in a 15-county region, according to a new study by the Bureau of Economic Geology at the University of Texas at Austin.

In all, some 55 billion gallons of water have been used in drilling activity between 1981, when natural gas production started in the Barnett Shale, and 2011, the latest year for which overall water use figures were available, the study found. Drilling was very limited in the Barnett until about the mid-1990s and peaked in 2008-2009 before declining sharply in recent years.

While those water volumes aren’t negligible, they are “not much in the grand scheme of the water cycle” in the 10,000-square-mile Barnett Shale region, said lead researcher Jean-Philippe Nicot. In an interview with the Star-Telegram, Nicot, a water resources scientist, said he’s more concerned about the surface impacts of drilling, such as chemical spills, than the quantity of water used.

The study, published in Environmental Science & Technology, estimated that statewide, hydraulic fracturing accounted for about 0.5 percent of total water use in 2011. Nicot noted that in parts of the state that are drier and are seeing more intensive energy development, water use for hydraulic fracturing can be a bigger issue.

That concern is expressed in another recent study by Ceres, a group with about 130 member organizations that advocates for sustainable economic practices. That report, issued last week, said “rapid hydraulic fracturing growth in Texas, the nation’s most active shale energy state by far, is causing serious water competition challenges.”

That national study focused on drilling in South Texas’ Eagle Ford Shale and the Permian Basin in West Texas and New Mexico. It noted that nearly all the wells drilled in those fields are in areas of “high or extremely high water stress.”

Ceres and the UT study found similar use of water in the state for hydraulic fracturing. Ceres estimated use at 25 billion gallons in 2012, and the UT study estimated 26.6 billion gallons in 2011.

Dan Mueller, director of natural gas exploration and production at the Environmental Defense Fund, said in a prepared statement that “understanding the historical evolution of its water use is invaluable to assess the water footprint for energy production.” But each of the nation’s energy-producing areas is different, he said, and “water use for hydraulic fracturing, and other water uses for that matter, varies dramatically by region and by localized areas.”

Sharon Wilson, organizer of the Texas Oil & Gas Accountability Project for the environmental group Earthworks, said collecting accurate statistics on water use can be difficult and “water use is often underreported,” and not just for energy.

“They don’t really know what the number is,” Wilson said, adding that she has heard from landowners in Montague County complaining that their water wells are running dry because of heavy withdrawals of groundwater by drillers. She said water use for fracking is fundamentally different than household use or irrigation because the water leaves the hydrologic cycle of evaporation and precipitation as it is used and disposed of.

Water use by hydraulic fracturing as a percentage of total water use varies widely by county, depending on the level of drilling compared to other water consumption, such as municipal use, agriculture and industry. In the Barnett, population is the biggest factor in overall water use, whereas in West Texas agriculture is a bigger factor.

For example, in Tarrant County, hydraulic fracturing accounted for about 2.9 billion gallons in 2011, the UT study says. That amounts to about 2.5 percent of the county’s total water use that year of about 115 billion gallons, Nicot said.

But in sparsely populated Montague County, one of the busiest counties for drilling in the Barnett in recent years, hydraulic fracturing accounted for about 36 percent of total water use in 2011, Nicot said.

Ceres said that West Texas’ Glasscock County ranked among the biggest Permian Basin water users for hydraulic fracturing. In that arid climate, however, energy use was just about a tenth of the water reportedly used for irrigation.

According to the UT study, the average Barnett Shale well used between 3 million and 5 million gallons for hydraulic fracturing in recent years, roughly a 60 percent increase since the mid-2000s. Greater use per well was driven by longer horizontal wellbore lengths, called laterals, and that has kept water use relatively high even as the number of wells drilled declined.

The study also looked at disposal of wastewater from hydraulic fracturing by underground injection, and found that the amount injected in the Barnett is even more than the amount of water used for fracturing. Nicot said the Barnett Shale is “an anomaly” among shale fields in that a high percentage of injected water flows back, accompanied by naturally occurring groundwater produced along with the oil or natural gas.

Only about 5 percent of this flowback fluid has been recycled for reuse, the study estimates.

The study was financed by the University of Texas Energy Institute.

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