A research team led by the University of Texas at Austin (UT) is collaborating with nine natural gas producers on a major field study to measure methane emissions at onshore gas well sites, about which only a handful of empirical data exist.

Anadarko Petroleum Corp., BG Group plc, Chevron Corp., Encana Oil & Gas (USA) Inc., Pioneer Natural Resources Co., Royal Dutch Shell plc, Southwestern Energy Co., Talisman Energy USA and ExxonMobil Corp. subsidiary XTO Energy Inc. agreed to provide the researchers access to production facilities in several key unconventional plays, including the Barnett, Eagle Ford, Fayetteville, Haynesville and Marcellus shales, as well as the Denver-Julesburg Basin.

“The major focus of the field work is quantifying emissions from well completions, gas well liquid unloading and well workovers — activities that have not been extensively characterized to date — in addition to other routine well site fugitive emissions,” UT said.

The study, to be completed in January, is to obtain “scientifically rigorous, representative data from multiple producing basins.” The Environmental Defense Fund (EDF) also is participating, as well as environmental testing firms URS and Aerodyne Research. Field measurements began in May and are to continue over the next few weeks.

“This study is unparalleled in its scope and approach,” said principal investigator David Allen, who directs UT’s Center for Energy and Environmental Resources within the Cockrell School of Engineering. “Through the data our research team collects from wells and facilities in the nation’s major shale producing areas and the data we receive from the nine participating natural gas producers, we hope to bring hard, scientific findings to an environmental issue that is still not well understood.”

Researchers plan to estimate the methane emission rates from the participating operators’ gas production sites, including hydraulically fractured wells, with direct measurement techniques at a sample of the drilling locations. The data is to be used to create a “better understanding of the amount of methane that is emitted into the atmosphere,” which then could guide well site management policies.

The researchers agreed that natural gas burns “substantially cleaner than other fossil fuels,” and that the abundance from unconventional resources “is helping reduce U.S. carbon dioxide emissions,” UT said. “However, some reports have raised questions about the overall effect of natural gas usage on total U.S. greenhouse gas emissions because of widely varying assumptions concerning the potential emissions of methane during extraction and production processes.

“Just how much methane is released into the atmosphere during these processes is highly uncertain because the measured data is limited and drilling and completion processes have evolved rapidly in recent years. The less methane leaked into the atmosphere, the more the climate benefits of using natural gas as compared to other fossil fuels are preserved.”

EDF Chief Counsel Mark Brownstein, who heads the group’s natural gas efforts, said the study was “unique in that it brings multiple, key stakeholders to the table to make measurements of emissions at the well pad. “If we want natural gas to be an accepted part of a strategy for improving energy security and moving to a clean energy future, it is critical for all of us to work together to quantify and reduce methane emissions as may be appropriate. Such a strategy could yield enormous environmental and health benefits.”

According to UT, the participants “all support advancing the science related to air emissions from natural gas production activities, and they look forward to accurate and fact-based scientific results.”

An advisory panel composed of six academic experts in fields relevant to the study is acting as an independent adviser. Final results are to be published in a peer-reviewed journal and are to be publicly available. Allen, who is leading the study, disclosed that he serves on the science advisory board for the U.S. Environmental Protection Agency and is a consultant for “several industry groups,” UT said. UT and Pennsylvania State University have come under fire in recent months because some natural gas studies were conducted by university researchers who had not disclosed industry ties.