Recent studies have reported methane (CH₄) emissions from abandoned oil and gas wells across the United States and the United Kingdom. These emissions can reach hundreds of kg CH₄ per year per well and are important to include in greenhouse gas emission inventories and mitigation strategies. Emission estimates are generally based on single, short-term measurements that assume constant emission rates over both short (hours) and longer (months/years) time periods. To investigate this assumption, we measure CH₄ emissions from 18 abandoned oil and gas wells in the USA and the UK continuously over 24 h and then make repeat 24 -h measurements at a single site over 12 months. While the lack of historical records for these wells makes it impossible to determine the underlying leakage-pathways, we observed that CH₄ emissions at all wells varied over 24 h (range 0.2-81,000 mg CH₄ hr⁻¹) with average emissions varying by a factor of 18 and ranging from factors of 1.1–142. We did not find a statistically significant relationship between the magnitude of emissions and variability or that variability is correlated with temperature, relative humidity or atmospheric pressure. The results presented here suggest high CH₄ emission events tend to be short-lived, so short-term (< 1 h) sampling is likely to miss them. Our findings present the dynamic nature of CH₄ emissions from abandoned oil and gas wells which should be considered when planning measurement methodologies and developing greenhouse gas inventories/mitigation strategies. Incorporation of these temporal dynamics could improve national greenhouse gas emissions inventories.

最近的研究报告了美国和英国各地废弃的油气井中的甲烷（CH ₄）排放。每口井每年的排放量可达数百公斤CH ₄，对于将其纳入温室气体排放量清单和缓解策略非常重要。排放估算通常基于单个短期测量，这些测量假定在短（小时）和较长（月/年）时间段内的恒定排放率。为了研究这个假设，我们测量CH ₄美国和英国的18口废弃油气井的碳排放量持续超过24小时，然后在12个月内在单个站点重复进行24小时测量。尽管缺乏这些井的历史记录，无法确定潜在的泄漏途径，但我们观察到所有井中的CH ₄排放量在24小时内变化（范围为0.2-81,000 mg CH ₄ hr ^-1），平均排放量变化为系数是18，系数是1.1-142。我们没有发现排放量与可变性之间的统计显着关系，也没有发现可变性与温度，相对湿度或大气压相关。此处显示的结果表明CH ₄高发射事件往往是短暂的，因此短期（<1小时）采样可能会错过它们。我们的发现提出了废弃油气井中CH ₄排放的动态性质，在计划测量方法和制定温室气体清单/缓解策略时应考虑这些因素。纳入这些时间动态可以改善国家温室气体排放清单。