Drillers using hydraulic fracturing in the Barnett Shale were among the largest users of water when plumbing the depths in search of oil and natural gas, according to a first-ever nationwide analysis of water usage by energy companies by the U.S. Geological Survey.
In a peer-reviewed paper to be published in Water Resources Research, energy companies working in the watershed that includes the 5,000-square mile Barnett Shale natural gas field used an average of 2.6 million to 9.7 million gallons of water per well from 2011 to 2014.
The study also states that water usage by wells that were fracked has drastically increased over more than a decade ago from a median of about 177,000 gallons to about 4 million for oil-producing wells and 5 million gallons for those tapping into natural gas reserves. By comparison, an Olympic-size swimming pool holds about 166,000 gallons of water.
“We started this study because there seemed to be a concern about water usage and we wanted to provide more information to put those concerns into context,” said Tanya Gallegos, a USGS scientist and lead author of the paper.
She said the study, which also found that fracked wells used less water than suspected in some areas, could help policymakers discuss the environmental impacts of the drilling practice. “It also will help us manage and plan for usage of our water. There is not an unlimited amount of water,” Gallegos said.
Fracking involves the injection of water, sand and chemicals underground to break apart shale rock and free trapped oil or gas. Using this process, along with the technique of horizontal drilling, has allowed drillers to access oil and gas fields that were difficult to work. But the drilling method has been linked to possible water contamination and seismic activity, the study states.
A recent study by the University of Texas at Arlington found elevated levels of numerous metals and chemical compounds associated with fracking in public and private wells in the Barnett Shale. Scientists at Southern Methodist University also linked the oil and gas process to a rash of earthquakes northwest of Fort Worth in 2013 and 2014.
The USGS study used data from IHS Energy for about 82,000 wells covering January 2000 to August 2014. The study notes that not all of the fractured oil and gas wells in the country are included since reporting requirements differ across the country.
It also found that the amount of water varies depending on the shale formation, with the Eagle Ford, Barnett and Haynesville-Bossier in Texas among those that used the most water. In 52 out of the 57 watersheds with the highest average water use for hydraulic fracturing, over 90 percent of the wells were horizontally drilled, the study states.
While there was an increase in the number of wells horizontally drilled since 2008, about 42 percent completed in 2014 were still either vertical or directionally drilled, and those wells used less than 687,000 gallons of water, according to the study.
Gallegos and the other authors caution against making too many leaps with their data, especially since the widespread use of the lower-water-use vertical and directional wells explains, in part, why the amount of water used per well varies so much across the country.
“Because hydraulic fracturing is not a one-size-fits all operation, assumptions and generalizations regarding water use in hydraulic fracturing operations and the potential for environmental impacts should be made with caution,” the study states.
A small percentage
The amount of water being sold for fracking in North Texas has been declining, an official said.
In 2009, at the peak of the Barnett Shale boom, the Tarrant Regional Water District said it sold 1.1 billion gallons of water for fracking purposes, or about 1.02 percent of the water it sold that year, according to Chad Lorance, district spokesman.
The amount of water sold for drilling has been dropping ever since, with 86.2 million gallons sold in 2014 accounting for 0.073 percent, he said. The district’s operations span an 11-county area reaching from Jack County to Freestone County.
By comparison, the agency said that 38.5 billion gallons of water in 2014 went toward outdoor use, which includes watering laws and filling swimming pools.
“The water we sold for fracking purposes in 2014 was a literal drop in the bucket compared to the water we sold to our wholesale customers,” Lorance said.
Max B. Baker, 817-390-7714