An energy industry-backed study of methane emissions at well sites published Monday relies on a too-small sample that was selected by industry participants where “best practices” emissions reductions are already in place; therefore, it’s findings are not broadly applicable, critics said Tuesday. However, industry analysts suggested that the research and more to follow could take some of the greenhouse gas (GHG) emissions heat off of the natural gas industry.

The first of 16 methane emissions studies focusing on unconventional natural gas production and organized by the Environmental Defense Fund (EDF) said industry efforts to control emissions at well sites are having a significant impact (see Shale Daily, Sept. 17). The research involved more than 90 partners, including universities, scientists, research facilities, and oil and gas companies.

On Tuesday the group Physicians, Scientists, and Engineers for Healthy Energy (PSE) complimented the effort; however, the research is “fatally flawed,” they said.

“The research bears directly on the powerful GHG/global warming effects of methane and thus the implications for regulation and continued widespread development of shale gas,” PSE said. “But it has concluded that methane leakage at well sites, selected in time and location by industry participants, is so low as to be nearly trivial. This is a finding at odds with other researchers’ work that shows much higher rates.”

Separately, analysts at ClearView Energy Partners LLC said in a note Tuesday that the findings of the EDF/industry study could help dispel some of the concern over methane leakage stirred up by a 2011 study by Cornell researchers (see Shale Daily, April 13, 2011). ClearView noted that there is plenty more research — 15 more papers — to come from the EDF/industry camp, and this will address other aspects of the natural gas value chain downstream of the wellhead.

The Environmental Protection Agency’s (EPA) GHG regulations “are progressing through GHG emissions source categories in descending order, from largest to smallest,” ClearView said. “Future findings concerning the midstream and downstream segments that diminish the system-wide footprint of oil and gas operations could potentially refocus EPA on NSPS [New Source Performance Standards] for GHG emissions from refineries that the agency appears to have mothballed.”

However, PSE maintains that the EDF/industry wellhead research doesn’t let the natural gas off the hook there, and the downstream emission of methane needs to be considered, too.

Weighing in for PSE on the EDF/industry study were Anthony Ingraffea, the Dwight C. Baum professor of engineering at Cornell University and PSE president; and Seth B. Shonkoff, also of PSE and an environmental researcher at the University of California, Berkeley.

The PSE scientists said the study is based on a small sampling of hydraulically fractured wells that may not adequately represent national oil and gas activity and the variability within and across production basins. The fugitive methane losses reported by the study are 10 to 20 times lower than those calculated from more complete (field-level) measurements, Ingraffea and Shonkoff said.

The EDF/industry study concluded that methane emissions from the gas industry amount to 0.42% of gross annual domestic production of associated gas from oil wells and nonassociated gas from gas wells, they said, adding that the researchers made “no attempt” to discuss other findings that are in conflict with their own. “How might one explain this huge discrepancy in measured emissions?”

Ingraffea and Shonkoff said the well selection process for the study is a problem and suggested that the study used the cream of the crop of wells, at least as far as low emissions are concerned.

“While it is possible that the gas industry can produce gas with relatively low associated emissions at the well site, this is likely not now the norm nationally, regionally, or even within a single production play,” the scientist said. “It is in the interest of industry to select lower-emitting wells for sampling.

“Studies carried out by NOAA [National Oceanic and Atmospheric Administration] and other independent researchers, which report significantly higher rates of emissions rely, on atmospheric measurements and chemical analysis of atmospheric samples to assess emissions across the entirety of a production field rather than a small subset of selected wells. As such, these studies are more likely to reflect accurately real-world emissions from the industry as a whole.”

The scientists also said industry involvement in the study and the fact that operators knew their wells were being watched played a role in the findings. “…[W]hen industry knows that they are being carefully watched they are motivated to, and capable of, substantially reducing fugitive methane emissions at the well site,” they said. “However, in the real world, not every well has oversight by scientists and engineers…In fact, many state oil and gas regulatory agencies in the United States have too few inspectors to monitor the large numbers of wells and regulatory oversight is, thus, greatly limited.”

Ingraffea and Shonkoff said the EDF/industry study “failed to employ basic scientific rules, including transparent criteria for the selection of study sites to measure, sufficient sample sizes, and the attempt to place their results in the context of other scientific studies to date. This study falls short in its attempt to help answer questions about methane emissions from modern gas development beyond the small number of gas industry-selected wells where measures were taken.”