Page 407 - Fundamentals of Gas Shale Reservoirs

OTHER AIR EMISSIONS 387
Colorado (UC) at Boulder published a new paper on methane U.S. oil and gas are projected to increase 4.5% by 2018
leakage in the journal Geophysical Research Letters. It as emissions from industry growth—particularly in oil
reports an alarmingly high level of methane emissions in the production—outpace reductions from regulations already
Uintah Basin of Utah—6.2–11.7% of total production for an on the books. However, the industry could cut methane
area about 1000 square miles. The scientists have 3 h of emissions by 40% below projected 2018 levels at an average
observations, and no direct way of knowing whether those annual cost of less than 1 cent per thousand cubic feet of
observations are representative of methane emissions over produced natural gas by adopting available emissions‐
longer periods of time. Most emissions in the basin are due control technologies and operating practices. This would
to gathering, processing, and transmission, rather than the require a capital investment of $2.2 billion, which Oil &
fracking process itself. A GAO study in 2010 estimated that Gas Journal data shows to be less than 1% of annual industry
a full 93% of fugitive methane emissions came from pneu- capital expenditure.
matic devices and glycol dehydrators—equipment used in The full life cycle impact of natural gas production is
gathering, processing, and transmission, not in fracking attracting increased interest as studies such as Horwarth’s
itself (GAO, 2010). Indeed, the GAO estimates only 4% of surface and energy policies include an expanded role for
emissions come from well completions. natural gas. All sources of the so‐called greenhouse gases
Two other recent studies help frame the debate over are important and every effort to reducing those methane
methane emissions. A study conducted by the University of emissions should be a priority for the natural gas industry.
Texas and sponsored by the Environmental Defense Fund Any methane emissions are unwanted. But it is important to
and nine petroleum companies takes a comprehensive look separate emissions from above ground operations versus
at the extent to which methane leaks during drilling and pro- fracking itself. Fortunately, there are straightforward tech-
duction offset the environmental benefits of the clean‐ nological requirements that can be imposed on gathering
burning natural gas the wells produce and was the first to and processing systems that would greatly cut down on this
conduct detailed examinations of individual drilling sites leakage. The Howarth study is an important reminder that
(Allen et al., 2013a). The study concluded that emissions the whole life cycle impact is what matters, not just the
of methane, a greenhouse gas and primary component of immediate emissions.
natural gas, were lower than previously estimated during
well completion but are higher than previously estimated
from other aspects of production, including from pneumatic 18.6 OTHER AIR EMISSIONS
controllers and equipment leaks. The study’s finding that
99% of methane emissions during completion are captured Other air quality impacts from shale gas operations include
by containment measures is significantly greater than had emissions of carbon dioxide stripped from the gas, volatile
been previously estimated using engineering estimates and organic compounds, sulfur dioxide and/or hydrogen sulfide
emissions factors developed in the early 1990s. The report from treating sour water for use as hydraulic fracture fluid,
estimates the national methane leakage rate associated with and NOX and other emissions from compressors, pollution
the phase of natural gas extraction to be equivalent in line from diesel engines, and ground level ozone. EPA has iden-
with EPA’s current emission inventory estimate for the pro- tified these emissions as one of the largest sources of air
duction segment of the supply chain. A second study coau- pollution from the energy industry and is working on new
thored by the Colorado NREL and Joint Institute for Strategic emission regulations for all oil and gas field productions.
Analysis and published in the journal Science in February In response to tightening emissions standards and to
2014 (Brandt et al., 2014), reviewed more than 200 earlier reduce operational costs, companies such as Cabot Oil &
studies. The study concluded that methane leakage was not Gas, a leading independent natural gas producer with
great enough to negate the climate benefits of switching significant operations in the Marcellus, recently announced
from coal to natural gas as a fuel for electricity although that it is using natural gas from the Marcellus to fracture
methane emissions are 50% higher than the estimates by the wells via an innovative dual‐fuel technology. The use of this
EPA. The authors said that fracking likely accounts only for technology, which uses engines that operate on a mixture of
a small portion of the excess methane emissions. Natural gas both natural gas and diesel, may help reduce the use of
production and processing, leaks from distribution systems, diesel—the traditional fuel of choice to operate hydraulic
and abandoned oil and gas wells are all likely to be larger fracturing equipment—by as much as 70%.
sources of fugitive emissions. According to a statement released by the company, dual‐
Finally, an analysis released in March 2014 by ICF fuel technology offers several benefits, including (1)
International shows that the U.S. oil and gas industries reduced air emissions for a cleaner environment, due to a
can significantly and cost‐effectively reduce emissions of reduction in diesel usage, (2) reduced truck traffic when
methane using currently available technologies and operating field gas at or near the well site is used due to a reduction in
practices (Economic, 2014). Total methane emissions from the transportation of diesel fuel to site, and (3) reduced