Role of Intermittency on the Effectiveness of Methane Emissions Detection at Oil and Gas Facilities: Comparative Assessment of Optical Gas Imaging and Site-wide Surveys

Intermittent emission events are a significant source of methane emissions from oil and gas operations. New technologies such as site-wide aerial surveys promise more effective detection of intermittent emission events compared to conventional optical gas imaging (OGI) surveys. In this work, we present case studies to assess role of intermittent emission events on the emissions reduction equivalence between conventional OGI-based surveys and site-wide screening surveys with new technologies. We find that the equivalence condition between OGI-based surveys and site-wide screening is robust against different assumptions about the duration of large emitters. As duration of large emitters decrease, monthly site-wide screening surveys are more effective at detecting large emitters compared to quarterly OGI monitoring. However, the contribution of large emitters to total emissions also decreases, which reduces the impact of the higher detection effectiveness of site-wide surveys. In addition, annual OGI survey as part of site-wide screening strategy is more critical when the detection threshold of the screening technology is greater than 10 kg/h or higher as the screening survey does not detect below detection threshold emissions.