New Solutions Needed to Recycle Fracking Water

Rice University Scientists Seek Long-term Answers to Stem Increase of Water Use at Wells

Rice University scientists have performed a detailed analysis of water produced by hydraulic fracturing (aka fracking) of three gas reservoirs and suggested environmentally friendly remedies are needed to treat and reuse it.

More advanced recycling rather than disposal of "produced" water pumped back out of wells could calm fears of accidental spillage and save millions of gallons of fresh water a year, said Rice chemist Andrew Barron. He led the study that appeared this week in the Royal Society of Chemistry journalEnvironmental Science: Processes and Impacts.

The amount of water used by Texas drillers for fracking may only be 1.5 percent of that used by farming and municipalities, but it still amounts to as much as 5.6 million gallons a year for the Texas portion of theHaynesvilleformation and 2.8 million gallons forEagle Ford. That, Barron said, can place a considerable burden on nearby communities.

Barron noted that shale gas wells, the focus of the new study, make most of their water within the first few weeks of production. After that, a few barrels a day are commonly produced.

The project began with chemical analysis of fracking fluids pumped through gas-producing shale formations in Texas, Pennsylvania and New Mexico. Barron and the study's lead author, Rice alumnus Samuel Maguire-Boyle, found that shale oil and gas-produced water does not contain significant amounts of thepolyaromatic hydrocarbonsthat could pose health hazards; but minute amounts of other chemical compounds led them to believe the industry would be wise to focus its efforts on developing nonchemical treatments for fracking and produced water.

Currently, fracturing fluid pumped into a well bore to loosen gas and oil from shale is either directed toward closed fluid-capture systems when it comes out or is sent back into the ground for storage. But neither strategy is an effective long-term solution, Barron said.

Fracking fluid is 90 percent water, Barron said. Eight to nine percent of the fluid contains sand or ceramicproppantparticles that wedge themselves into tiny fractures in the rock, holding open paths for gas and oil to escape to theproduction well.

The remaining 1 or 2 percent, however, may contain salts, friction reducers, scale inhibitors, biocides, gelling agents, gel breakers and organic and inorganic acids. The organic molecules either occur naturally or are a residue from the added components.

The researchers found most of the salt, organic and other minerals that appear in produced water from shale gas reservoirs originate in theconnate waterstrapped in the dense rock over geologic time scales.

Source: Rice University

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