'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.