Satellite-based estimates of nitrogen oxide and methane emissions from gas flaring and oil production activities in Sakha Republic, Russia

Abstract

Crude oil production activities and associated petroleum gas (APG) flaring are responsible for significant air polluting and greenhouse gas (GHG) emissions and have negative effects on the environment and climate. In Russia, one of the world's major oil producers, APG flaring remains a routine practice despite regulatory policies. We present the first analysis of nitrogen oxide and methane emissions over Tas-Yuryakh and Talakan oil fields in Sakha Republic (Eastern Siberia, Russia) using multi-satellite observations. Satellite-based TROPOMI (TROPOspheric Monitoring Instrument) nitrogen dioxide (NO2) mean fields show local NO2 enhancements corresponding to the locations of gas flares detected from Sentinel 2 imagery and VIIRS (Visible Infrared Imaging Radiometer Suite) fire data. We derive the annual nitrogen oxide (NOx = NO2+NO) emissions from TROPOMI NO2 observations using an exponentially-modified Gaussian model. We obtain NOx emissions up to 1.34 mol/s (in 2019) in Tas-Yuryakh, where persistent production APG flaring is detected, and about 0.6 mol/s in Talakan, where oil production is three times larger than in Tas-Yuryakh but gas flaring is employed only occasionally. In 2019 we observe a new flaring site in Tas-Yuryakh from the NO2 mean fields, corresponding to an increase in the environmental fees paid by the companies to the local budgets. Assuming that all NOx emissions are associated with APG flaring, the volume of gas flared for 2019 is estimated at 1.25 ± 0.48 billion cubic metres (bcm) in Tas-Yuryakh and 0.5 ± 0.2 bcm in Talakan. Furthermore, we find a clear methane (CH4) anomaly of about 30 ppb from the TROPOMI XCH4 mean fields near Talakan oil field. We estimate CH4 emissions of about 28–63 tons/h from individual TROPOMI XCH4 plumes using the cross-sectional flux method. The estimated satellite-based NOx and CH4 emissions are higher than the inventories, which are expected to underestimate the contribution from the oil and gas industry and are generally available with several years of delay. TROPOMI NO2 and CH4 observations demonstrate their capability in identifying emission sources from space with unprecedented detail. The results show how satellite observations can support environmental authorities in monitoring the emissions from the oil and gas industry and the commitment of oil companies in reducing APG flaring.