'Green' Completions Reduce Gas Industry Emissions

The State Journal
28 September 2011
By Pam Kasey

Some producers already use "green" practices that reduce their greenhouse gas, or GHG, emissions and improve their bottom lines.

In an ongoing debate about the level of lifecycle greenhouse gases emitted by natural gas from shale formations, one analysis says it's more than coal, others say less.

But as the U.S. Environmental Protection Agency seeks comment on regulations that would cut a variety of oil and gas industry air emissions, some producers already use "green" practices that reduce their greenhouse gas, or GHG, emissions and improve their bottom lines.

"It makes business sense to do it," said Andrew Place, director of public policy research for Pittsburgh-based EQT.

It has been long and widely said that natural gas emits half the greenhouse gases of coal, a generalization based on a comparison of carbon dioxide emissions when the two are burned for electricity.

But a March study from Cornell University looking at the "lifecycle," extraction-to-end use GHG footprint of shale gas, set off a public debate.

The Cornell study noted that the high-volume hydraulic fracturing the industry developed a decade ago for "completing" natural gas wells drilled into shale formations -- that is, making them ready for production -- releases large volumes of methane, a far more potent GHG than carbon dioxide.

The researchers estimated that, including methane released during completion and methane leaked afterward during processing, transmission, storage and distribution, as much as 8 percent of a shale well's final volume could be lost to the atmosphere. Their study concluded that the global warming potential of shale gas exceeds that of coal on a 20-year time horizon and, because methane decays faster than the carbon dioxide-dominated emissions released by coal, it is comparable on a 100-year horizon.

A spate of studies followed, one in process at the same time as Cornell's and others in response to it. A National Energy Technology Laboratory report in May and August papers from Carnegie Mellon University and the Worldwatch Institute found, variously, that the use of a 20-year time horizon is non-standard in the scientific

community and discounts the future too heavily while disadvantaging natural gas; that the industry does not and would not tolerate the loss of as much as 8 percent of its product; and that even with lifecycle emissions considered,

the global warming potential of shale gas compares favorably with coal for electricity production on a 100-year time horizon.

Scientists in both camps, however, acknowledged the high release of methane from shale gas wells during completion. The NETL paper, for example, used an estimate of 47 thousand cubic feet, or Mcf, of methane released during completion of a conventional well, compared with more than 11,000 Mcf released during a completion in the Barnett shale.

That relatively small release during conventional well completion is vented off or flared.

But for the larger volume of methane brought to the surface during completion of a shale well, technologies and practices are available for green completions that capture the methane, preventing its release to the atmosphere and making it available for processing and sale.

Shale gas production took off in the early 2000s, first in the Barnett shale in Texas, then in other shales, and in the Marcellus in the latter part of the decade.

Companies extracting gas from shale recognize the methane losses during high-volume hydraulic fracturing.

But because capturing that methane for sale requires getting a sales pipeline in place before a well is completed, EQT's Place said, and because historically some wells drilled in new plays come up dry, producers have wanted to gain experience in each shale play before making those pipeline investments up front.

As each shale play has matured, some operators have begun using green completions.

"It's interesting now in the Marcellus because you're not wildcatting, you're not going to come up with a dry well,"

Place said. "You can plan ahead because you know within reasonable certainty how much gas will come up -- there's no downside for investing the substantial sum to get the sales line there ahead of time."

EQT is executing green completions on nearly every Marcellus well, Place said, flaring only in a new field where infrastructure has not caught up.

He hesitated to estimate how much methane the company is capturing that might previously have been flared, noting that each well is unique and saying only that green completions address a "significant" part of shale gas's GHG emissions.

Green completions are just a matter of internal planning for EQT, Place said, because the company has a midstream arm, Equitable, that handles pipeline.

"It's a matter of having access to capital, staffing and technological expertise to put the pieces together. For larger operators, even if they don't have a midstream arm, they can make these midstream arrangements," he said.

"It's not a real challenge except for maybe a smaller operator who has little acreage that may not be co-located."

The EPA wants to minimize methane emissions from the oil and gas industry, which it says amount to almost 4 percent of U.S. GHG emissions and which are increasing with the rapid growth in shale gas production.

Proposed agency regulations open for public comment until Oct. 24 would reduce methane and other air emissions from the industry. The proposed means for methane reductions at the wellhead are those in use now by EQT and other producers.

For information on the proposal, visit http://epa.gov/airquality/oilandgas; to file a comment online, go to http://www.regulations.gov and type "EPA-HQ-OAR-2010-0505-0002" in the search box.