The Proceedings of the National Academy of Sciences recently published a study conducted by the University of Texas that measured methane emissions from natural gas production, focusing specifically on emissions at well sites conducting hydraulic fracturing operations.
The study included the direct measurement of methane emissions at 190 natural gas sites with 489 wells in the Gulf Coast, Midcontinent, Rocky Mountain, and Appalachian regions from May 2012 through December 2012. The study concluded that emissions of methane, a greenhouse gas and primary component of natural gas, were lower than previously estimated during well completion but are higher than previously estimated from other aspects of production, including from pneumatic controllers and equipment leaks. The study’s finding that 99% of methane emissions during completion are captured by containment measures is significantly greater than had been previously estimated using engineering estimates and emissions factors developed in the early 1990s.
The use of horizontal drilling and hydraulic fracturing techniques is projected to grow significantly in the coming years. The results of this study likely came as a surprise to the U.S. Environmental Protection Agency who to date focused most of its efforts on controlling emissions during well completion. While the data collected is necessarily site-specific, the study should be helpful to the oil and gas industry to identify best practices to further prevent methane loss from equipment and to environmental/oil and gas regulators in tailoring future regulations to address those emissions sources that can be controlled cost effectively.
Sources: here and here