Controlled release testing of the static chamber methodology for direct measurements of methane emissions

Abstract

Abstract. Direct measurements of methane emissions at the component level provide the level of detail necessary for developing actionable mitigation strategies. As such, there is a need to understand the magnitude of component level methane emission sources and test methane quantification methods that can capture methane emissions from component level sources. The static chamber method is a direct measurement technique that is being applied to measure large and complex methane sources such as oil and gas infrastructure. In this work we compile component level methane emission factors from the IPCC emission factor database to understand the magnitude of component level methane flowrates, review the tested flowrates and measurement techniques from 38 controlled release experiments, and perform 64 controlled release testing of static chambers methodology with mass flowrates of 1.02, 10.2, 102, and 512 grams of methane per hour (g/hour). We vary the leak properties, chamber shape, chamber size, and usage of fans to evaluate how these factors affect the accuracy of the static chamber method. We find that 99 % of component level methane emission rates from the IPCC emission factor database are below 100 g/hour, and that 76 % of previously-available controlled release experiments did not test for methane mass flowrates below 100 g/hour. We find that the static chamber method quantified methane flowrates with an overall accuracy of ±14 %, and that optimal chamber configurations (i.e., chamber shape, volume, usage of fans) can improve accuracy to below ±5 %. We find that smaller chambers (<20 L) performed better than larger volume chambers (>20 L), regardless of the shape of chamber or usage of fans. However, we found that the usage of fans can substantially increase the accuracy of larger chambers, especially at higher mass flowrates of methane (>100 g/hour). Overall, our findings can be used to engineer static chamber systems for future direct measurement campaigns targeting a wide range of sources, including landfills, manholes, and oil and natural gas infrastructure.

Methane Emissions from Abandoned Oil and Gas Wells in Alberta and Saskatchewan, Canada: The Role of Surface Casing Vent Flows

“…We measured all sites that could be measured according to site access and configuration and did not consult provincial surface casing vent flow or gas migration databases during site selection to limit potential bias. We quantified methane flow rates at each well site using a twostep process including chamber-based measurements, 1,21,22 which are described in the Supporting Information.…”

“…Aerial or vehicle-based surveys can reduce site access issues and potentially increase the number of wells screened and identify more superhigh emitters. Nevertheless, direct component-level and site-level measurements are still needed to measure lower flow rates ( 10 4 mg/h) and to differentiate between collocated sources, 9,22 such as surface casing vent and non-surface casing vent emissions.…”