Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
Scientific Aviation, Boulder, Colorado 80301, United States.
Environ Sci Technol. 2020 Apr 21;54(8):5112-5120. doi: 10.1021/acs.est.0c00179. Epub 2020 Apr 13.
Methane (CH) emissions from oil and gas activities are large and poorly quantified, with onshore studies showing systematic inventory underestimates. We present aircraft measurements of CH emissions from offshore oil and gas platforms collected over the U.S. Gulf of Mexico in January 2018. Flights sampled individual facilities as well as regions of 5-70 facilities. We combine facility-level samples, production data, and inventory estimates to generate an aerial measurement-based inventory of CH emissions for the U.S. Gulf of Mexico. We compare our inventory and the Environmental Protection Agency Greenhouse Gas Inventory (GHGI) with regional airborne estimates. The new inventory and regional airborne estimates are consistent with the GHGI in deep water but appear higher for shallow water. For the full U.S. Gulf of Mexico our inventory estimates total emissions of 0.53 Tg CH/yr [0.40-0.71 Tg CH/yr, 95% CI] and corresponds to a loss rate of 2.9% [2.2-3.8%] of natural gas production. Our estimate is a factor of 2 higher than the GHGI updated with 2018 platform counts. We attribute this disagreement to incomplete platform counts and emission factors that both underestimate emissions for shallow water platforms and do not account for disproportionately high emissions from large shallow water facilities.
甲烷（CH）排放来自石油和天然气活动，数量巨大且难以量化，陆上研究表明清单存在系统低估。我们展示了 2018 年 1 月在美国墨西哥湾进行的海上石油和天然气平台 CH 排放的飞机测量结果。飞行过程中对单个设施以及 5-70 个设施的区域进行了采样。我们将设施层面的样本、生产数据和清单估算相结合，为美国墨西哥湾生成了基于航空测量的 CH 排放清单。我们将我们的清单和美国环境保护署温室气体清单（GHGI）与区域航空估计值进行了比较。新的清单和区域航空估计值与 GHGI 在深水区域是一致的，但在浅水区似乎更高。对于整个美国墨西哥湾，我们的清单估计总排放量为 0.53Tg CH/yr[0.40-0.71Tg CH/yr，95%置信区间]，对应于天然气产量的损失率为 2.9%[2.2-3.8%]。我们的估计值比 2018 年更新的平台数量的 GHGI 高出一倍。我们将这种差异归因于不完整的平台计数和排放因子，这些都低估了浅水区平台的排放量，并且没有考虑到来自大型浅水区设施的不成比例的高排放量。
