The towering flares that turn night into day in the Marcellus Shale gaslands are becoming an increasingly rare sight.
Natural gas producers are turning to new techniques to capture the gas emitted during the well-completion process. In the past, a well's initial production was typically vented or burned off to allow impurities to clear before the well was tied into a pipeline.
Now, more operators are employing reduced-emission completions - a "green completion" - a process in which impurities such as sand, drilling debris, and fluids from hydraulic fracturing are filtered out and the gas is sold, not wasted.
The five gas wells that EQT Corp. completed in October at this remote site in Washington Township, Pa., are typical. Compared to a gas flare, which roars like a jet engine and licks the sky with flame like a giant welder's torch, green completion is dull and quiet.
EQT is not the only drilling company that has embraced green completions. The equipment for separating the gas from the "flowback" has been perfected in the past decade, and in the next three years, using it will become standard practice across the nation.
The U.S. Environmental Protection Agency approved new rules this year requiring green completions nationwide by 2015, except for exploratory wells unconnected to pipelines. As of Oct. 15, drillers can no longer vent the gas into the atmosphere without burning.
The EPA says green completions will save drillers up to $19 million a year by capturing natural gas that would be wasted.
The advent of green completions is an example of the rapid development of shale-gas technology, which has revived a flagging domestic energy sector in just a few years.
"What was true yesterday is no longer true today," said Andrew Place, director of public policy research at EQT, based in Pittsburgh. "Systems are evolving."
Much of the new technology has been driven to address fears about drilling, including hydraulic fracturing, the extraction technique that has turned impermeable shale into a bonanza of oil and gas.
"Public concerns have pushed the engineers to come up with solutions," Place said.
Activists and regulators are paying more attention to air emissions from shale-gas development, including toxins emitted during drilling and production. Much of the focus has been on releases of methane, the main component of natural gas as well as a potent greenhouse gas, though there is substantial disagreement over studies attempting to measure the methane leaks.
In devising the new rules, the EPA said it was acting under its Clean Air Act mandate to reduce emissions of volatile organic compounds and pollutants such as benzene, which can cause cancer. The agency said the new rules were expected to eliminate 95 percent of the smog-forming volatile organic compounds emitted from more than 13,000 new gas wells each year.
The EPA said a "co-benefit" of green completions was a reduction in methane emissions by 1 million to 1.7 million tons a year.
The government delayed full implementation of the rule until 2015 to allow the industry to build enough equipment to handle the workload.
The American Petroleum Institute and other industry groups are challenging the new rules in the U.S. Court of Appeals in Washington. So are environmental groups.
"We'd say the rules have not gone far enough," said Jay Duffy, a staff attorney with Philadelphia's Clean Air Council, which joined with Earthjustice in October to notify the EPA it planned to sue.
Duffy praised the EPA for taking action to curb toxic emissions from drilling, but he contends the federal agency failed to directly confront the climate-change issue. The EPA concluded in 2009 that greenhouse gases endangered public health and welfare, but it has not devised standards on methane emissions.
Anti-drilling activists argue that so much methane escapes from gas development it undermines the industry's claims about the clean-air benefits of the shale-gas boom.
The industry says environmentalists and the EPA are using inflated, biased estimates of methane emissions. It has denounced as hoaxes some of the infrared videos posted online that purport to show methane plumes.
Some industry leaders say the biggest benefit to green-completion technology is that they hope it puts the emissions controversy to rest.
"I do think it addresses a criticism that the industry has had in terms of methane emissions, and maybe we can take that off the table," Jack P. Williams Jr., president of XTO Energy, said in a recent interview.
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EQT differs from many gas-exploration companies because it also serves a retail customer base through its gas utility in southwestern Pennsylvania, Equitable Gas Co. It says green completions achieve a significant emission reduction.
"EQT has an interest in minimizing our impact, our air impact in this case, in the basin where we have a social license to operate," said Place, a deputy secretary of the Pennsylvania Department of Environmental Protection before he went to work for EQT.
"We've been here for 120 years," he said. "We live in this community."
At EQT's drilling site on Pettit Run Road in rolling farmland about seven miles northwest of Waynesburg, Pa., workers explained the kind of assembly-line drilling operation they have devised that now incorporates green completions.
Before EQT began drilling on this five-acre site carved out of a hillside, the company first extended its pipeline network to the location so it would be ready to receive any gas produced, said Michael Rehl, manager of completion operations.
During the spring, the five wells were drilled in a row, 15 feet apart, to a depth of about 7,500 feet, where they turn horizontally into the Marcellus Shale layer and follow parallel paths, separated by about 1,000 feet. Then the wells were lined with several layers of steel pipe and concrete, and hydraulically fractured.
The completion process commenced in October when a contractor, Pure Energy Services Ltd., began cleaning out wells one at a time.
At the outset, a well disgorges mostly sand, water, and chemicals used during the fracking process, along with drilling debris and minerals such as barium and manganese picked up from the shale formation. After about four days, the well produces mostly natural gas.
During a green completion, the mixture is routed through a series of filters. A cylindrical sand trap collects the solid materials, which are sent to a landfill. The water, containing the chemicals and mineral contaminants, is treated and stored for reuse in the next drilling operation.
And the natural gas is channeled into a pipeline and sent off to market, rather than being flared into the sky to achieve no other purpose than to heat the planet.
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