Research Digest 012

Christopher G. Nixon
Greenhouse Gas Scientist

In this article

The Highwood Bulletin is our way of sharing what we learn. We publish regular updates on emissions management news, novel research, and special insights from our team of experts and our partners.


With methane quantification research gaining momentum by the day, it was truly difficult to narrow this Research Digest down! In this edition, we recap the latest measurement-based inventory research, exciting progress on super-emitter quantification, and the latest results from satellite quantification, including the very first published results from NASA’s latest orbital emissions detection technology, EMIT.

First Orbital Emissions Observations from NASA’s EMIT

The first methane and carbon-dioxide observations from NASA’s EMIT imaging spectrometer aboard the international space station are presented. Emissions from energy-producing countries in the Middle East and Central Asia are analyzed. 88.7% of methane emissions in the countries analyzed here are from oil and gas, and 8.2% from the waste sector; the largest total country wide methane emissions are observed in Turkmenistan (731 tCH4/h). The authors indicate EMIT is almost 100 times more sensitive than TROPOMI, and demonstrate its ability to identify, geolocate, and quantify multiple emission sources in close proximity (<1 km). They conclude that these capabilities and EMIT’s 60m spatial resolution are needed to close carbon budgets here.

Thorpe, A. K., Green, R. O., Thompson, D. R., Brodrick, P. G., Chapman, J. W., Elder, C. D., … & Miller, C. E. (2023). Attribution of individual methane and carbon dioxide emission sources using EMIT observations from space. Science advances9(46), eadh2391.

Super-Emitter Methane Estimation From Satellite Data in Algeria

Methane data from Sentinel-2 and TROPOMI satellite instruments are used to estimate 2020 emissions in Algeria; in the Hassi R’Mel gas field and oil-production-dominated Hassi Messaoud region. Emission time series are estimated for 11 super-emitters and combined with the remaining diffuse area. The analysis indicates that more of Algeria’s methane emissions (∼75%) come from oil production than nationally reported (5%). The authors state that due to the availability of global data from both TROPOMI and Sentinel-2, their system can be used in other regions, especially those with low cloud cover and uniform surface albedo such as Libya and Iran. They recommend that addressing the largest super-emitters can significantly reduce emissions in Algeria. However, they caution that the majority of sources are individually below the Sentinel-2 detection limit (1–2 t/h), meaning that optimal region-wide emissions reductions will likely require general infrastructure improvements beyond addressing the largest super-emitters here.

Naus, S., Maasakkers, J. D., Gautam, R., Omara, M., Stikker, R., Veenstra, A. K., … & Aben, I. (2023). Assessing the Relative Importance of Satellite-Detected Methane Superemitters in Quantifying Total Emissions for Oil and Gas Production Areas in Algeria. Environmental Science & Technology57(48), 19545-19556.

Geostationary Monitoring of Large Methane Sources

Large transient methane sources are monitored in the US using the Geostationary Operational Environmental Satellites (GOES). This work shows that GOES’s 1-2 km resolution can monitor very large methane point sources in the Americas with up to 5-min continuous coverage. The full evolution of an extreme methane release from a natural gas pipeline in Durango, Mexico on 12 May 2019 is tracked, totalling ~ 1200 tCH4 over 3 hours. The authors infer, from other detections, a detection limit of 10 to 100 t/h. The authors argue that due to extreme releases of methane often lasting less than an hour, as from deliberate venting, these would be difficult to identify and quantify with low-Earth orbit satellites. The results are described as highlighting the importance of developing dedicated geostationary satellite instruments to monitor greenhouse gasses, due to near-real-time detection of extreme methane point sources, here.

Watine-Guiu, M., Varon, D. J., Irakulis-Loitxate, I., Balasus, N., & Jacob, D. J. (2023). Geostationary satellite observations of extreme and transient methane emissions from oil and gas infrastructure. Proceedings of the National Academy of Sciences120(52), e2310797120.

Upstream Measurement Based Inventories in Saskatchewan

Two comprehensive aerial surveys of upstream oil and gas infrastructure are used to derive measurement-based methane inventories in Saskatchewan, Canada. The authors observe that “Saskatchewan is the most methane intense oil and gas producer in Western Canada by a significant margin”. They state their results reveal the futility of relative reduction targets and argue that regulations should be designed to meet independently measurable emission intensities. They conclude by considering relevance of the impending import restrictions in the European Union here.

Conrad, B. M., Tyner, D. R., & Johnson, M. R. (2023). The Futility of Relative Methane Reduction Targets in the Absence of Measurement-Based Inventories. Environmental Science & Technology.

Hybrid Methane Inventories for Upstream Oil and Gas in Alberta

Two aerial surveys in Alberta, Canada, are used to develop a measurement-based, source-resolved, hybrid top-down/bottom-up methane inventory for upstream oil and gas. The authors state that derived methane intensities are approximately 4 times those in neighbouring British Columbia, highlighting the importance of independent monitoring, reporting, and verification in reducing emissions. With their source-resolved measurement-based inventory exceeding official estimates by 50%, the authors stress the importance of a third-party in monitoring, reporting, and verification (MRV) frameworks here.

Conrad, B. M., Tyner, D. R., Li, H. Z., Xie, D., & Johnson, M. R. (2023). A measurement-based upstream oil and gas methane inventory for Alberta, Canada reveals higher emissions and different sources than official estimates. Communications Earth & Environment4(1), 416.

Alberta Methane Measurements in Midstream, End-Use, and Upstream Facilities

Aerial mass balance measurements are conducted in Alberta at 16 upstream O&G facilities and 24 midstream and end-use facilities. Investigated sites are on average reported to emit 1.7 (upstream) and 3.4 (midstream/end-use) times more methane than reported. The authors underscore the importance of empirical measurements of midstream/end use emissions, stating that they are crucial for gap bridging measurement data. Observing that energy buyers are increasingly demanding O&G products with lower CH4 footprints, the authors stress the importance of measurement-based reporting instead of conventional emission factors multiplied by activity here.

Li, H. Z., Seymour, S. P., MacKay, K., Wang, J. S., Warren, J., Guanter, L., … & Xie, D. (2023). Direct measurements of methane emissions from key facilities in Alberta’s oil and gas supply chain. Science of The Total Environment, 169645.

Measurement-Based Emissions Estimates in the Delaware Basin

Two types of oil and gas equipment-based methane emissions inventories are compared for the Delaware Basin. One, using EPA emission factors, estimates emissions at 315 Gg CH4/y (0.6% gas loss). Another, using region-specific measurement data, estimated emissions of 1500 Gg CH4/y (2.8% loss). The researchers observe that the largest discrepancies resulted from, in descending order: Large fugitive emissions from oil production, updating maintenance activity emissions, considering flaring inefficiency, and the inclusion of associated gas venting. The authors suggest that “a systematic underestimate probably exists in current bottom-up inventories” and strongly recommend emission factors should be validated. They conclude by recommending areas of further development to mitigate the gaps between bottom-up and top-down methods: Dynamic emission factors/activity data, Temporal variability in emissions, Data collection frequency/latency/absence, Granular facility-level data collection, Data quality/reliability, Customized approach for different facilities in basin-wide models, Collaboration/data sharing, and Policy updates as deserving critical attention here.

Riddick, S. N., Mbua, M., Santos, A., Hartzell, W., & Zimmerle, D. J. (2024). Potential Underestimate in Reported Bottom-up Methane Emissions from Oil and Gas Operations in the Delaware Basin. Atmosphere15(2), 202.

Estimating Source Duration with Operational Data

A novel framework to estimate the duration of aerially detected methane emissions is presented. The authors discuss implementation of the framework, in which detected emissions may be estimated with engineering estimates, emissions factors, detection information, default durations, and/or operational data. The authors propose aircraft-based screening to enhance methane emission inventories, while noting the limitation of snapshot-based measurements. The complementary nature of the aircraft-based methane screening data and process data is underscored — the authors predict this combination will be important for understanding and quantifying emissions for emission inventories. They recommend that good policy design would consider evolving technology, novel techniques, and integrating multiple kinds of information here.

Higgins, S., Hecobian, A., Baasandorj, M., & Pacsi, A. P. (2023). A practical framework for oil and gas operators to estimate methane emission duration using operational data. SPE Journal.

Investigation of GHG Emissions at Decommissioned Unconventional Wells in BC

Integrity of nine abandoned unconventional wells is investigated through emissions evaluation of surrounding soil in the Montney region of BC. The researchers observe that over half of the unconventional wells are potentially releasing both fugitive CO2 and CH4 into the surrounding soil, although CH4 is likely mitigated significantly by soil-based oxidation. They state the merits of further investigating natural soil-based CH4 mitigation. The authors conclude by recommending further monitoring and evaluation of unconventional well integrity in all relevant jurisdictions here.

Cahill, A. G., Joukar, M., Sefat, M., & van Geloven, C. (2023). Evaluating methane emissions from decommissioned unconventional petroleum wells in British Columbia, Canada. Geophysical Research Letters50(24), e2023GL106496.

Analysis of Low-Cost Fixed-Sensor LDAR Framework

A prototypical low-cost fixed sensor program framework is defined and considered from an operational perspective. Large operational costs are caused mainly by (i) follow-up callouts, (ii) nontarget emissions, and (iii) maintenance requirements; these are identified by the authors as areas for improvement. The authors discuss the issue of ineffective alerts in low-cost fixed sensors, suggesting better sensors, improved quality management, and better algorithms as potential solutions. However, they suggest a possible limit for program cost competitiveness. It is suggested that for cost competitiveness, regulators may need to allow flexibility to selectively ignore alerts; this presents a considerable challenge for regulators. Caution with presently available low-cost fixed sensor LDAR programs is recommended here.

Barchyn, T. E., Hugenholtz, C. H., Gough, T., Vollrath, C., & Gao, M. (2023). Low-cost fixed sensor deployments for leak detection in North American upstream oil and gas: Operational analysis and discussion of a prototypical program. Elementa: Science of the Anthropocene11(1).

The Highwood Bulletin is our way of sharing what we learn. We publish regular updates on emissions management news, novel research, and special insights from our team of experts and our partners.

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