Quantifying atmospheric methane emissions from oil and natural gas production in the Bakken shale region of North Dakota

Abstract

Abstract We present in situ airborne measurements of methane (CH 4 ) and ethane (C 2 H 6 ) taken aboard a NOAA DHC‐6 Twin Otter research aircraft in May 2014 over the Williston Basin in northwestern North Dakota, a region of rapidly growing oil and natural gas production. The Williston Basin is best known for the Bakken shale formation, from which a significant increase in oil and gas extraction has occurred since 2009. We derive a CH 4 emission rate from this region using airborne data by calculating the CH 4 enhancement flux through the planetary boundary layer downwind of the region. We calculate CH 4 emissions of (36 ± 13), (27 ± 13), (27 ± 12), (27 ± 12), and (25 ± 10) × 10 3 kg/h from five transects on 3 days in May 2014 downwind of the Bakken shale region of North Dakota. The average emission, (28 ± 5) × 10 3 kg/h, extrapolates to 0.25 ± 0.05 Tg/yr, which is significantly lower than a previous estimate of CH 4 emissions from northwestern North Dakota and southeastern Saskatchewan using satellite remote sensing data. We attribute the majority of CH 4 emissions in the region to oil and gas operations in the Bakken based on the similarity between atmospheric C 2 H 6 to CH 4 enhancement ratios and the composition of raw natural gas withdrawn from the region.