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November 18, 2013
Study quantifies methane emissions

The results of a study that measured fugitive methane emissions from hydraulically fractured gas wells received significant attention at a recent hearing of the Oversight Subcommittee of the Senate’s Environment and Public Works Committee. 

The study found that fugitive methane emissions from well completions were much lower than estimates the EPA had included in its national emissions inventory.  But the study also found that methane emissions from certain equipment used at natural gas wells were higher than EPA’s estimates.  Overall, total methane emissions from all the natural gas production wells monitored in the study were comparable to the Agency’s estimates.

Methane, the principle component of natural gas, is many times more powerful as a greenhouse gas (GHG) than carbon dioxide (CO2).

190 representative wells

The study was a product of a collaboration between nine energy companies, researchers from the University of Texas at Austin (UT), and the Environmental Defense Fund (EDF), which initiated the project.  According to the EDF, the study was the first of its kind to directly measure fugitive methane emissions from a large selection of wells that used hydraulic fracturing to extract gas from shale formations. 

According to David Allen, the UT engineering professor who led the research team, measurements were taken from 190 hydraulically fractured natural gas well completions that were representative of company operations in the Gulf Coast, Mid-Continent, Rocky Mountain, and Appalachian regions.  The companies that participated in the study account for 16 percent of natural gas production and roughly half of new gas well completions in the United States.   

In discussing the study, Republican senators at the hearing emphasized how wrong the EPA had been in its emissions estimates for well completions and how the Agency’s New Source Performance Standards (NSPS) requiring emissions controls at gas wellheads were based on faulty information.  In a statement, the EDF countered that the low emissions from well completions were early evidence that the NSPSs were working. 

99 percent control

A well completion is a process that clears sand and liquids from a fractured well.  For two-thirds of the completion flowbacks sampled, Allen stated that control equipment reduced methane emissions by 99 percent—that is, only 1 percent of the methane leaving the well during completion flowback was emitted to the atmosphere.

Allen also reported that methane emissions from certain types of pneumatic equipment that include control devices such as valves on well sites are 30 percent to several times higher than EPA’s estimates for this equipment.  The researchers estimated that, combined, emissions from pneumatics and equipment leaks account for about 40 percent of national emissions of methane from natural gas production.

More studies to follow

The peer-reviewed wellhead study is the first in a series of 16 studies under the EDF-led initiative that will measure methane emissions from the entire natural gas supply chain, which also includes gathering lines, processing facilities, long-distance pipelines, storage, local distribution, and commercial trucks and refueling stations.  The EDF says that more than 90 partners are involved in the overall project, including universities, scientists, research facilities, and oil and gas companies.

Smart regulation

At the hearing, Mark Boling, representing Southwestern Energy Company, noted that for his company, the real impetus behind reducing methane emissions has been EPA’s Natural Gas Star Program, which Southwestern joined in 2005.  Boling testified that since 2006, Southwestern has reported cumulative methane reductions of over 37 billion cubic feet primarily due to their use of reduced emissions completions, also called green completions.  The EPA included the green completion process as a major part of its revised NSPS (40 CFR Part 60, Subpart OOOO, or Quad O). 

“Southwestern believes that the ‘Quad O’ regulations are ‘smart regulations’ as they effectively manage [VOC] emissions (and indirectly methane emissions) from the production sector by requiring proven, cost-effective technologies and practices to reduce VOC emissions,” testified Boling.  “In fact, much of the equipment, controls, and practices required by ‘Quad O’ have already been implemented by Southwestern and many other companies that participate in the Natural Gas Star Program.”

Testimony from the hearing

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