ANNA KARION | National Oceanic and Atmospheric Administration
"Methane Emissions Estimates from Oil and Natural Gas Production Using Atmospheric Measurements"
The recent development of horizontal drilling technology by the oil and gas industry has dramatically increased onshore U.S. natural gas and oil production in the last several years. This production boom has led to widespread interest from the policy and scientific communities in quantifying the climate impact of the use of natural gas as a replacement for coal. Quantifying this climate impact requires an understanding of the magnitude of methane emissions from natural gas and oil operations, because methane, the primary component of natural gas, is also a powerful greenhouse gas.
Several recent scientific field studies have focused on using atmospheric measurements to estimate natural gas methane emissions in different production basins. Methane can be measured precisely with commercial analyzers, and aircraft-based measurements of methane, coupled with meteorological measurements, allow researchers to estimate emissions from regions of concentrated gas and oil production. Ethane, other light hydrocarbons, and carbon isotope measurements can be used as tracers for differentiating natural gas emissions from those of other methane sources, such as agriculture or landfills, which do not contain any non-methane hydrocarbons and have a different isotopic signature.
Here we will present estimates of methane emissions to the atmosphere from natural gas and oil production in two different unconventional basins in the U.S.: the Uinta (in Utah) and the Denver-Julesburg (in Colorado), along with preliminary results from a more recent measurement campaign in the Barnett Shale (in Texas). Our results are based primarily on atmospheric composition observations from instrumented light aircraft and ground-based meteorological measurements. We find that current emissions inventories for the first two regions may be underestimated by a factor of two, indicating that further study is needed to identify the sources of the discrepancies between inventories and top-down estimates based on atmospheric measurements.