Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA.
Center for Energy and Environmental Resources, University of Texas at Austin, 10100 Burnet Road, Austin, TX 78758, USA.
Sci Total Environ. 2022 Jul 10;829:154277. doi: 10.1016/j.scitotenv.2022.154277. Epub 2022 Mar 8.
In comparing observation based methane emission estimates for oil and gas well sites to routine emissions reported in inventories, the time scale of the measurement should match the time scale over which the inventoried emissions are estimated. Since many measurements are of relatively short duration (seconds to hours), a tool is needed to estimate emissions over these time scales rather than the annual totals reported in most emission inventories. This work presents a tool for estimating routine emissions from oil and gas well sites at multiple time scales; emissions at well sites vary over time due to changes in oil and gas production rates, operating practices and operational modes at the sites. Distributions of routine emissions (expected and inventoried) from well sites are generally skewed, and the nature and degree to which the distributions are skewed depends on the time scales over which emissions are aggregated. Abnormal emissions can create additional skew in these distributions. At very short time scales (emissions aggregated over 1 min) case study distributions presented in this work are both skewed and bimodal, with the modes depending on whether liquid storage tanks are flashing at the time of the measurement and whether abnormal emissions are occurring. At longer time scales (emissions aggregated over 1 day) distributions of routine emissions simulated in this work can have multiple modes if short duration, high emission rate events, such as liquid unloadings or large abnormal emissions, occur at the site. Multiple applications of the methane emission estimation tool (MEET), developed in this work, are presented. These results emphasize the importance of developing detailed emission inventories, which incorporate operational data, when comparing measurements to routine emissions. The model described in this work supports such comparisons and is freely available.
在将基于观测的油气井场甲烷排放估算与清单中报告的常规排放进行比较时，测量的时间尺度应与估算清单排放的时间尺度相匹配。由于许多测量的持续时间相对较短（几秒钟到几小时），因此需要一种工具来估算这些时间尺度上的排放，而不是大多数排放清单中报告的年度总量。这项工作提出了一种用于估算多个时间尺度上的油气井场常规排放的工具；由于油、气产量的变化、站点的操作实践和操作模式，井场的排放随时间而变化。井场常规排放（预期和清单）的分布通常是偏态的，分布偏态的性质和程度取决于排放汇总的时间尺度。异常排放会使这些分布产生额外的偏态。在非常短的时间尺度（排放在 1 分钟内汇总）下，本研究中提出的案例研究分布既有偏态又有双峰，取决于测量时是否有液体储罐闪蒸以及是否存在异常排放。在较长的时间尺度（排放在 1 天内汇总）下，本工作中模拟的常规排放分布如果在站点发生短时间、高排放率事件（如液体卸载或大的异常排放），则可能有多个峰。本文介绍了多次应用甲烷排放估算工具（MEET）的情况。这些结果强调了在将测量值与常规排放进行比较时，开发详细的排放清单（包括操作数据）的重要性。本文中描述的模型支持这种比较，并且是免费提供的。
