Repeated leak detection and repair surveys reduce methane emissions over scale of years

Abstract

Reducing methane emissions from the oil and gas industry is a critical climate action policy tool in Canada and the US. Optical gas imaging-based leak detection and repair (LDAR) surveys are commonly used to address fugitive methane emissions or leaks. Despite widespread use, there is little empirical measurement of the effectiveness of LDAR programs at reducing long-term leakage, especially over the scale of months to years. In this study, we measure the effectiveness of LDAR surveys by quantifying emissions at 36 unconventional liquids-rich natural gas facilities in Alberta, Canada. A representative subset of these 36 facilities were visited twice by the same detection team: an initial survey and a post-repair re-survey occurring ∼0.5-2 years after the initial survey. Overall, total emissions reduced by 44% after one LDAR survey, combining a reduction in fugitive emissions of 22% and vented emissions by 47%. Furthermore, >90% of the leaks found in the initial survey were not emitting in the re-survey, suggesting high repair effectiveness. However, fugitive emissions reduced by only 22% because of new leaks that occurred between the surveys. This indicates a need for frequent, effective, and low-cost LDAR surveys to target new leaks. The large reduction in vent emissions is associated with potentially stochastic changes to tank-related emissions, which contributed ∼45% of all emissions. Our data suggest a key role for tank-specific abatement strategies as an effective way to reduce oil and gas methane emissions. Finally, mitigation policies will also benefit from more definitive classification of leaks and vents.

Methane emissions from upstream oil and gas production in Canada are underestimated

“…1 ). This variability has been documented in recent Canadian studies, at both regional 10 , 17 , and component-level scales 12 , 19 , 20 , as a function of several determinants. In no particular order, the first determinant is the fluid type.…”

Field Performance of New Methane Detection Technologies: Results from the Alberta Methane Field Challenge

“…Davis Safety Consulting Inc. ('OGI crew') was selected to collect baseline methane emissions data using OGI technology based on prior participation and experience in collecting researchquality data [15]. The OGI crew used a FLIR Technologies' GF-320 infrared camera for emissions detection and the Providence Photonics QL-320 quantitative optical gas imaging (QOGI) instrument for emissions quantification.…”

“…While recent studies have found OGI-based LDAR surveys effective in detecting and reducing emissions, they are time-consuming and expensive [10], [15]. OGI-based surveys involve a 2person crew covering 4 -6 well sites per day, which does not scale effectively across thousands of geographically sparse well sites.…”

“…OGI-based surveys involve a 2person crew covering 4 -6 well sites per day, which does not scale effectively across thousands of geographically sparse well sites. This makes frequent monitoring challenging even as other studies point to the need to quickly find and repair stochastic, high-emitting leaks [16]- [18].…”

A Machine Learning Approach to Methane Emissions Mitigation in the Oil and Gas Industry

“…While assessing model impact on time and financial investment, we assume an average OGI-based LDAR survey speed of 5 sites/day at a cost of $3000/day, observed in typical field conditions and follows EPA guidelines [9,10]. Figure 1 shows the number of super-emitter sites surveyed across the three survey scenarios.…”