Quantifying methane emissions from oil and gas operations in the New Mexico Permian Basin

Methane leakage from point sources in the oil and gas industry is a major contributor to global greenhouse gas emissions. The majority of such emissions come from a small fraction of ``super-emitting" sources. The characteristics and the prevalence of these relatively rare super-emitting events cannot be thoroughly explored with conventional surveys that sample a small subset of the oil and gas asset population. This study analyzes methane emissions from the upstream and midstream oil and gas sector in the New Mexico part of the Permian Basin, by taking advantage of a population-level dataset from aerial surveys. The mean loss rate estimate of 9.4\% (+3.6\%/-3.2\%, 95\% CI) from our analysis is significantly higher than the 2.2\% national average loss rate in the upstream and midstream O\&G sectors. Part of the reason for the discrepancy is New Mexico Permian Basin specific. With the rapid development and the low price environment, the tools and incentives for operators to cut methane emissions are limited in this region. Secondly, the conventional ground-based surveys tend to have fewer than enough representative super-emitters in the sample and underestimate the total emissions, given the underlying heavy-tailed distribution of emission sizes.

Compared to estimates from satellite observation-based inversion modeling, our emission estimate is also higher. In addition to the conservative inversion modeling approach, the discrepancy can also be attributed to the observations from satellites with constant afternoon overhead times that are not representative of daily-average methane enhancement caused by emissions. The aerial survey finds that emission incidences vary across the day, with morning surveys more likely to see emissions than afternoon surveys. One possible explanation is that more well operations and maintenance work tend to happen in the morning in the Permian Basin to avoid the high afternoon temperatures often found in the region.