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1.0 Executive Summary

In the United States, oil and gas development is a significant anthropogenic source of atmospheric methane, a potent greenhouse gas, that is 86-times as climate forcing as carbon dioxide over a 20-year timeframe. Quantitative optical gas imaging (QOGI) is a method of atmospheric methane and hydrocarbon detection that can help to quantify methane emissions. From 2018 to 2019, Earthworks conducted a field sampling effort to measure methane emissions from upstream oil and gas sources in several states, including three oil and gas basins: Denver-Julesburg (Colorado), San Juan (Colorado and New Mexico), and Permian (New Mexico and Texas). This report aims to contextualize methane emission measurements collected by Earthworks using QOGI technology across these three select basins in 2018 and 2019 using methane emission estimates and measurements from the peer-reviewed literature and emissions inventories.

In this report we (1) review and summarize the peer-reviewed literature, government reports, and emissions inventories on methane emission measurements and estimates from the fields, equipment and facilities where Earthworks collected their QOGI-based methane emission measurements; (2) discuss oil and gas production trends over time in these select basins; and contextualize methane emissions measurements collected by Earthworks with QOGI technology using basin-level annual production, basin-level methane emissions estimates, and additional equipment-level methane emission measurements and estimates. Key limitations regarding data availability and quality and challenges comparing methane emission rates from various data sources are also discussed. Key findings from this assessment are summarized below:

  • Overall, basin-level methane emission rates — reported in the peer-reviewed literature and emissions inventories — generally appear to increase proportionally with oil and gas production trends in the San Juan Basin, Denver-Julesburg Basin, and Permian Basin overtime.
  • The majority of methane emission measurements collected by Earthworks fell within the range of methane emission estimates provided in the literature and emissions inventories for corresponding sources in the select basins, particularly for tanks and unlit flares.
    • Tanks: Earthworks’ methane emission measurements from tanks were lower than average values reported from tanks in the San Juan Basin and in the Permian Basin, but higher than average values reported from tanks in the Denver-Julesburg Basin.
    • Unlit flares: Methane emission rates from unlit flares detected by Earthworks also fell within the ranges presented in the literature. Earthworks’ average methane emission rates detected from unlit flares were above the average of values available in the literature in both the San Juan Basin and Permian In the San Juan Basin, Earthworks’ maximum detected emissions from unlit flares exceeded the maximum value reported in the literature for this basin. However, the maximum methane emission rate associated with unlit flares in the Permian Basin was far less (approximately half of) the maximum value reported in the literature and emissions inventories in the Permian Basin, indicating that in certain cases Earthworks’ measurements may underestimate methane emission rates from specific sources, such as unlit flares in this particular basin.
  • Earthworks detected methane emission rates from pipe fittings and pneumatic controllers in the San Juan Basin that exceeded rates presented in the literature and emissions inventories.
    • Pipe fittings and pneumatic controllers: Earthworks’ methane emission rates for pipe fittings and pneumatic controllers in the SJB were expanded over a wider range of values as compared to the reported estimates in the literature, often exceeding the maximum emission rate reported from these sources in the literature.

The limitations of this assessment are discussed in detail in the report. The key limitations include:

  • Limitations of data availability and uncertain representativeness of both the Earthworks’ dataset and the data presented in the peer-reviewed literature and emissions inventories
  • Challenges presented during Earthworks’ field sampling, including lack of site access and pad-level operational information, limited proximity to observed emission sources and lack of gas composition data for specific sources
  • Uncertainty regarding comparable source categories related to upstream oil and gas activities and equipment to enable accurate comparison of methane emission measurements across data

Despite these limitations, this report contributes to the current literature by assessing methane leakage associated with oil and natural gas development by situating equipment- level emission rates in the Denver-Julesburg, San Juan, and Permian Basins, measured by Earthworks using QOGI technology, within the methane emission estimates published in the peer-reviewed literature and methane emissions inventories. Additionally, this assessment contextualizes methane emissions observed during Earthworks data collection efforts with respect to trends of crude oil and natural gas production and basin-level methane emission estimates in previous years. Earthworks’ field sampling provides additional methane emission measurements to improve understanding about methane leakage associated with oil and gas development and to help to inform efforts aimed to reduce methane emissions from this sector.

Future projections of hydrocarbon production in the San Juan, Denver-Julesburg and Permian Basins indicate that methane emissions are anticipated to remain a matter of climate concern. Our assessment indicates that future research in this area should include detailed categorizations of methane emission sources, an increase in sample size per emission source collected over a longer time-horizons, and an examination of methane emissions sources in additional oil and gas basins.

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