Potential Underestimate in Reported Bottom-up Methane Emissions from Oil and Gas Operations in the Delaware Basin

Methane is a greenhouse gas and identified as a key driver of near-term climate change. Bottom-up approaches estimate annual methane loss from US natural gas production and transport at 6 Tg, but recent studies suggest this may be an underestimate. To investigate this possibility, an equipment-based...

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Bibliographic Details
Published in:Atmosphere 2024-02, Vol.15 (2), p.202
Main Authors: Riddick, Stuart N., Mbua, Mercy, Santos, Arthur, Hartzell, Wendy, Zimmerle, Daniel J.
Format: Article
Language:English
Subjects:
bottom-up
Climate change
Distribution
Emission analysis
Emission inventories
Emission measurements
Emissions
Emissions (Pollution)
Environmental aspects
Environmental monitoring
Estimates
Gas flaring
Gas production
Gas venting
Greenhouse gases
inventory
Methane
Methane emissions
Natural gas
oil and gas
Oil and gas operations
Oil and gas production
Oil production
Oils & fats
Petroleum industry
Petroleum production
reconciliation
Satellites
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Summary:Methane is a greenhouse gas and identified as a key driver of near-term climate change. Bottom-up approaches estimate annual methane loss from US natural gas production and transport at 6 Tg, but recent studies suggest this may be an underestimate. To investigate this possibility, an equipment-based emissions inventory, using EPA emission factors, was developed to calculate methane emissions from oil and gas operations in the Delaware basin, USA. Emission factors and activity data were then updated using contemporary and region-specific measurement data. The original inventory estimated emissions at 315 Gg CH4 y−1 (gas production-normalized rate of 0.6% loss), while the updated inventory estimated emissions of 1500 Gg CH4 y−1 (2.8% loss). The largest changes resulted from large fugitive emissions from oil production (+430 Gg CH4 y−1), updating maintenance activity emissions (+214 Gg CH4 y−1), considering flaring inefficiency (+174 Gg CH4 y−1), and the inclusion of associated gas venting (+136 Gg CH4 y−1). This study suggests that a systematic underestimate probably exists in current bottom-up inventories and identifies sources currently missing or may be incorrect. We also strongly recommend that emission factors should be validated through direct comparison against measurement campaigns that include long-tail distributions typical of oil and gas activities.
ISSN:2073-4433
2073-4433
DOI:10.3390/atmos15020202