Wednesday, November 3, 2010

What to do With Flowback? Just Pump it Back Downhole.

photo of Range Resources impoundment, courtesy SRBC
It takes anywhere from 3 to 5 million gallons of water to frack a Marcellus well, water that companies are pumping from local rivers or purchasing from municipalities. But, says Dave Yoxtheimer at Penn State University, drillers are looking into alternatives: treated wastewater, cooling water from power plants, and abandoned mine drainage. They’re also exploring ways to reuse their flowback and waste fluids.

A number of companies have engineered recycling technologies, including Aqua Pure and GE. But, says Tony Gaudlip, water operations manager for Range Resources, recycling flowback may be as simple as pumping it back down the hole. In an October 21 webinar Gaudlip said that Range Resources has been recycling 100 percent of their flowback for the past year. Reusing the water has resulted in a savings of $200,000 per well, about 5 percent of the total drilling cost.

We’re not talking a lot of flowback – only 10 percent of what’s injected comes back out. Still, the company’s engineers needed to consider a few things before pumping wastefluid back down the hole: pumping pressure – horizontal wells require about 80 to 100 barrels of water per minute to fracture the rock; and the chemicals they used. Fracturing Marcellus requires different chemicals than shale wells in other parts of the country.

“Initially we took the flowback and the brine, mixed it all together and pumped it downhole,” Gaudlip said. They watched the dials and gauges, looked at bacterial growth and scaling, and analyzed fluid stability. “We saw some increase in friction, but that was manageable,” Gaudlip said. What they didn’t see was scaling. Nor did they see an elevation of the total dissolved solids (TDS) levels. Conventional wisdom expected those levels to climb higher with each reuse.

What this meant for Range Resources was that they could reuse their fluids with minimum – or no – treatment. So for the past year they’ve been diluting the flowback in a new mix that’s three-quarters fresh water combined with one-quarter reused waste fluids.

Where do they store this flowback until they need it? In pits. Gaudlip admitted that Range Resources has had some issues with bacterial growth on the surface, which he attributed to the levels of polyacrilamides and solids in the flowback. So now, they truck their
flowback fluids to Eureka Resources, in Williamsport. After raising the pH, adding flocking agent to settle the solids and tossing in chlorine to control bacteria, the “clarified” waste fluid is hauled back to the well pad where it is stored until it’s reused in fracking.

The idea behind reusing drilling waste fluid was two-fold: to reduce the amount of water withdrawn from the rivers and streams, and to reduce the amount of truck traffic hauling both fresh and wastewater on the road. Gaudlip admits that trucking the flowback 35 miles to the treatment facility is not an ideal situation. Not for Range and not for the local residents.

Long term plans call for Range Resources to incorporate mobile water treatment units at their drilling sites. But that’s still a few months off, says Matt Pitzarella, Range Resource Public Affairs Director for the Marcellus region. The company’s ultimate goal, he said, is to maintain zero liquid discharge in Pennsylvania’s surface waters.

You can hear Gaudlip’s webinar presentation here. The longer article that was published in Broader View Weekly last week should be available here sometime next week.

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