Leak detection and repair data from California's oil and gas methane regulation show decrease in leaks over two years

Abstract

Leak detection and repair (LDAR) programs are commonly used to identify and mitigate unintentional emissions at oil and gas facilities. This study utilizes regulatory reporting data from 2018 to 2019 at over 300 facilities (including crude oil production, natural gas production, natural gas storage, and natural gas transmission) to evaluate the effectiveness of California's statewide LDAR requirements. The results from this study can offer guidance for other jurisdictions looking to reduce methane emissions from oil and gas facilities. Total leaks found in 2018 and 2019 were 11,359 and 7,208, respectively. Although the number of components surveyed increased from 2018 to 2019 by 16%, the number of leaks decreased over the eight quarterly surveys (slope [95% confidence interval]: -287 leaks/quarter [-395, -180]). In both 2018 and 2019, 20% of all leaks accounted for approximately 50% of estimated emissions from leaking components, demonstrating the importance of frequent LDAR surveys to mitigate emissions from larger leaks. Emission reductions from LDAR surveys were estimated by using correlation equations to roughly approximate emission rates based on measurements of concentration. In 2018 and 2019, emission reductions were 5,400 and 3,000 metric tons methane, respectively (∼9% and ∼4% of total fugitive methane emissions from oil and gas production and processing according to California's emissions inventory for 2018 and 2019).