NGFE Reports: Shale Gas and Water Supply

Locally sourced water crucial to reducing shale gas drilling footprint

“A gallon saved is a penny earned,” said Dave Yoxtheimer, who is a hydrogeologist at Pennsylvania State University in the US, of the water used in shale gas drilling operations.

“We try to make every gallon count in Pennsylvania, so taking flowback and reusing it has been the choice,” he added.

Yoxtheimer spoke about water supply considerations in drilling for shale gas at the Global Shale Gas Summit in Warsaw, Poland.

“Is there water near your project?” he queried. “When the leasing craze happened, not many operators considered if there was an availability of a reliable water source and how close it was. If you can avoid trucking that in, you can save lots of money. Finding local sources keeps the public’s ire down.”

It is also a question, he said, of whether water availability is seasonal or year round. “Store it if you get it and need it later,” said Yoxtheimer. “If it’s from a river or stream, you’ve got to leave enough for other users.”

According to him, water quality is also a consideration. “We have a history of coal mines which makes the water have a lower PH,” he said, adding, “it’s not good for fracking, so you may need to treat it.”

“In the US it takes quite a while to withdraw water from a stream or a river, up to two years,” said Yoxtheimer. “Budget is also a consideration.”

In Pennsylvania, the cost of water for shale gas drilling could depend on whether an enterprise is utilizing municipal or public water resources. Yoxtheimer explained, “If you truck it 50 or more miles it gets expensive. Groundwater wells are being considered and can be a cost effective way of accessing water, taking out the trucking equation. Waste water and cooling water are also being considered.”

He said there in Pennsylvania, there were a number of water use permit agencies: federal, a “river basin commission” as well as state and local authorities.

“For the Marcellus shale, water use is considered consumptive because it stays down there.”

Yoxtheimer also talked about water storage: centralized impoundment, single pad dedicated impoundment, frac tanks, which he said had a small footprint there) He advised, “Make sure impoundment is properly designed and built to specification.”

“Once you frac the well you get 15-20% back on the surface. Flowback from the Marcellus looks like a pint of Guinness. The mobile filtration process can be used to treat the water and reuse it to cycle it over again,” he said.

There were, he added, some parameters of concern including dissolved solids, suspended solids, metals, sulfates and carbonates which can affect well performance, and bacteria.

“Concentrate is hauled off for more treatment at centralized treatment facility,” explained Yoxtheimer. “Reuse has put the need for centralized treatment facilities on hold, it’s slowed the need because they’re reusing flowback.”

“If you’re doing a 4 million gallon frac, you get back 800,000 gallons back,” he remarked. “That’s 18 cents per gallon for treatment and trucking, so if you can reuse it you can get a cost savings of US$ 50,000.”

And, said Yoxtheimer, it would be possible to save thousands of gallons of water if drilling operations reuse their water and find a local water source.

“Local water sources keep trucks off the road, and keeps your operation off the radar.”

He added, “Integrated water resource management helps you meet your objectives while minimizing the environmental effects.”

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