courtesy Penn State Extension Shale Team
The Marcellus shale has become one of the large-scale unconventional natural gas resources, producing over 18 billion cubic feet per day. While this natural gas resource is important to the US energy portfolio, there has been a concern and need for more information on the emissions of greenhouse gases, largely methane, from all stages of shale gas development.
A group of researchers at several universities and research institutes issued the study, "Analysis of local-scale background concentrations of methane and other gas-phase species in the Marcellus Shale" in the journal, Elementa: Science of the Anthropocene on February 9, 2017. The study analyzed concentrations of methane in the Marcellus shale regions of southwestern and northeastern Pennsylvania in 2012 and in northeastern Pennsylvania again in 2015. The report found methane to be a higher concentrations in southwestern PA than in northeastern PA, indicating spatial variability in methane concentrations across the area. Methane was observed to be slighter greater in 2015 than in 2012, indicating background concentrations may have likely increased due to increased emissions in the region. Methane levels didn't seem to be influenced by well area density or by average production rates at the mobile sampling locations.
The equipment used for the monitoring was found to be useful for understanding ambient concentrations and emission of pollutants during the early stages of shale development and to help provide a baseline to help understand future impacts.
In January, 2017, researchers with the US Dept. of Energy's National Energy Technology Laboratory released a paper, "Synthesis of recent ground-level methane emission measurements from the US natural gas supply chain" in the Journal of Cleaner Production. The paper looks at various stages of the natural gas supply chain. Based on ground-based measurements, the study found 1.7% of the methane in natural gas is emitted between the extraction and delivery. The results indicate that gathering systems, production pneumatics, and unassigned emissions are the top three contributors to the emissions. The report states the concerted data collection effort has improved our understanding of methane emissions, but further data are necessary to resolve knowledge gaps and to help support environmentally responsible natural gas operations.