Fracking wastewater is mostly brines, not man-made fracking fluids

Fracking wastewater is mostly brines, not man-made fracking fluids
An unconventional shale gas well on the Fort Berthold Reservation in North Dakota. (Photo Credit: Avner Vengosh)

Naturally occurring brines, not man-made fracking fluids, account for most of the wastewater coming from hydraulically fractured unconventional oil and gas wells, a new Duke University study finds.

"Much of the public fear about fracking has centered on the chemical-laden fracking fluids—which are injected into wells at the start of production—and the potential harm they could cause if they spill or are disposed of improperly into the environment," said Avner Vengosh, professor of geochemistry and water quality at Duke's Nicholas School of the Environment.

"Our new analysis, however, shows that these fluids only account for between 4 and 8 percent of wastewater being generated over the productive lifetime of fracked wells in the major U.S. unconventional oil and gas basins," Vengosh said. "Most of the fracking fluids injected into these wells do not return to the surface; they are retained in the shale deep underground.

"This means that the probability of having environmental impacts from the man-made chemicals in fracking fluids is low, unless a direct spill of the chemicals occurs before the actual fracking," he said.

More than 92 percent of the flowback and produced water—or wastewater—coming from the wells is derived from naturally occurring brines that are extracted along with the gas and oil.

These brines carry their own risks, Vengosh stressed. They contain varying levels of salts, heavy metals and naturally occurring radioactive elements, and their sheer volume makes disposing of them a challenge.

"But with proper treatment, they potentially could have beneficial reuses," he said, "especially out West, where our study shows most brines being produced by fracked wells are much less saline than those in the East. These Western brines, which are similar in salinity to sea water, could possibly be treated and re-used for agricultural irrigation or other useful purposes, especially in areas where freshwater is scarce and drought is persistent."

The Duke team published its findings Oct. 14 in the peer-reviewed journal Science of the Total Environment.

The researchers used three statistical techniques to quantify the volume of wastewater generated from unconventional oil and in six basins nationwide: the Bakken formation in North Dakota; the Marcellus formation in Pennsylvania; the Barnett and Eagle Ford formations in Texas; the Haynesville formation in Arkansas, Louisiana and East Texas; and the Niobrara field in Colorado and Wyoming.

Using multiple statistical techniques "helped us more accurately account for changes in each well's wastewater volume and salinity over time, and provide a more complete overview of the differences from region to region," said Andrew J. Kondash, a doctoral student in Vengosh's lab at Duke's Nicholas School, who led the study.

"This makes our findings much more useful, not just for scientists but for industry and regulatory agencies as well," he said.

Among other findings, the new study shows that the median volume of wastewater produced by an unconventional oil or gas well ranges from 1.7 to 14.3 million liters per year over the first five to 10 years of production. The volume of produced water coming from these declines over time, while its salinity increases.

"The salt levels rise much faster than the volume declines, resulting in a high volume of saline wastewater during the first six months of production," Vengosh said. After that, the volume of produced by a well typically drops, along with its hydrocarbon output.

Elizabeth Albright, assistant professor of the practice of environmental science and policy methods at the Nicholas School, co-authored the study with Kondash and Vengosh.


Explore further

How much water does US fracking really use?

More information: Andrew J. Kondash et al, Quantity of flowback and produced waters from unconventional oil and gas exploration, Science of The Total Environment (2017). DOI: 10.1016/j.scitotenv.2016.09.069
Journal information: Science of the Total Environment

Provided by Duke University
Citation: Fracking wastewater is mostly brines, not man-made fracking fluids (2016, October 17) retrieved 22 September 2019 from https://phys.org/news/2016-10-fracking-wastewater-brines-man-made-fluids.html
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Oct 17, 2016
Relax guys, it's 92% naturally toxic water.

Just stop it. You mix household bleech to a lesser lesser concentrate than 8%.

Fracking fluid is specifically formulated to destroy the environment it's pumped into, don't tell me it's safe when it gets out

Oct 17, 2016
You really should kiss a Fracker today. Better abundant and cheap than the left's cold, dark alternatives.

Oct 17, 2016
Brine pollutes groundwater or aquifers and causes earthquakes by stressing strata beyond it's plastic limits in the context of it's setting the whole idea is failed, it's not based on petrology and tectonics where stressing strata does something over a time appropriate to the stress and duration.

The industry has proven it doesn't know where that tipping point is for Oklahoma, Texas and now Kansas why not spread it around?

I'm sure the real estate brokers and town officials love seeing their housing prices and tax base go away with every quake over M4 a bet, when they hit rock bottom how long before they sue?

Oct 17, 2016
Our global problem is like this, a full glacial cycle takes 100,000-years and CO2 varies 100-ppm, from 180-280-ppm, that's textbook Pleistocene-Holocene history averages.

During the 800k-year ice-core record the maximum CO2 was 305±5-ppm, 3 interglacials ago, ok, we passed that about 1916 and since then added 100-ppm ... let that sink in for rate-of-change.

That's a glacial cycle in only 100-years and it's all ABOVE the highest CO2 value ever reached in a million years, acidifying the oceans 10-times faster than an extinction event: ICES ASC 2013 plenary lecture by Dr Richard Feely, 9:10 into 1:01:08; https://www.youtu...ob9Wy45E

We must exit the Steam Age for electrons, most grid power is for thermal end-uses 80%, not electricity 20%, so to switch will only take 5-years moving to solar-HVAC, maybe 2-months if it was a war but don't tell.?

Oct 18, 2016
Shootist1 /5 (1) 5 hours ago
You really should kiss a Fracker today.


I've got a fracking well, so you can kiss my ass you dust farting POS spammy old oxygen thief!

Oct 18, 2016
That's fracking good news, until that "shit" eventually comes back up, unless of course, what goes down stays down.

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