Editor’s Note: The Farm and Dairy published a three-part series on Marcellus Shale earlier this fall. Follow these links for more information: Can a safe water drinking supply sustained?, Consulting an attorney and Sifting through the good and bad.

UNIVERSITY PARK, Pa. — Billions of dollars already have been invested by natural gas companies in Pennsylvania for Marcellus Shale gas exploration. Similarly, millions of gallons of water have been utilized to develop billions of cubic feet of natural gas.

Minimizing impact

The natural gas industry is pursuing ways to minimize potential environmental impacts during development of the rich Marcellus formation, such as by treating and reusing wastewater produced during the process.

However, according to one Penn State expert, as the Marcellus natural gas play grows, the demand for water for hydraulic fracturing will directly increase, as will the need for infrastructure to treat flowback water for reuse or disposal.

“To minimize the environmental and financial costs of flowback treatment, many operators are now reusing flowback and other impaired waters such as acid mine drainage,” said David Yoxtheimer, hydrogeologist and extension associate with Penn State’s Marcellus Center for Outreach and Research.

Featured speaker

Yoxtheimer was one of the featured speakers during an Oct. 21 Web-based seminar, Water Use and Water Reuse/Recycling in Marcellus Shale Gas Exploration and Production.

Sponsored by Penn State Cooperative Extension, the webinar provided an overview of new strategies to conserve fresh water and reuse waters affected by the gas exploration process.

When shale gas drillers develop natural gas using the hydraulic-fracturing technique, they inject 3 million to 5 million gallons of water, along with sand and a relatively low concentration of additives into the Marcellus formation to release the natural gas.

According to the Susquehanna River Basin Commission, about 10 percent (300,000 to 500,000 gallons) of the injected hydraulic-fracturing fluids return to the surface via the natural-gas well within about one month.

Flowback

This wastewater, known as “flowback,” contains relatively high concentrations of salt as well as some metals that were dissolved out of the shale during the fracturing process.

The flowback water requires treatment prior to release back into the environment, but many companies are now reusing the flowback for subsequent hydraulic-fracturing operations, which has environmental benefits and reduces truck traffic on roads.

“Simply reusing the water is only the first step, but the lack of processing back to the water-quality standards is a big challenge to conventional thinking,” said Tony Gaudlip of Range Resources.

Gaudlip, a co-presenter in the webinar, joined Range Resources in January 2008 following various industry positions in south Texas, Wyoming, the Middle East, Europe and Asia.

“We do not need crystal clear water to use as a base fluid for fracturing,” he said.

“We do not need to treat the water at all in order to get good production — no distillation, crystallization, reverse osmosis, nanofiltration, etc. That’s all unnecessary to meet new downhole requirements,” Gaudlip said.

Trends

“What Range is doing is different,” Yoxtheimer said. “The company is fairly progressive and basically is recycling 100 percent of its water, and other companies are now following that trend.”

Yoxtheimer added that reusing flowback — and using impaired waters such as acid mine drainage and effluent from municipal or industrial wastewater plants — greatly offsets the need to use fresh water drawn from local streams and rivers.

Yoxtheimer said that Marcellus development is “proceeding pretty much full steam ahead” in Pennsylvania despite some opposition.

“There are a lot of economic opportunities there that are potentially good, but also some potential environmental consequences. Ideally, a fine balance can be struck by doing the exploration and extraction in an environmentally responsible way.”