Methane emission detections and emission rate indications using handheld sensors at non-producing oil and gas wells

Abstract Methane (CH 4 ) is a potent greenhouse gas with large emissions from oil and gas infrastructure, including producing and non-producing wells. Non-producing oil and gas wells in Canada may contribute up to 13% of fugitive methane emissions from the oil and gas sector, yet there are challenges to cost-effective, fast, and reliable monitoring of the 425 000 non-producing wells in the country. This challenge is not unique to Canada, as there are ∼4 million non-producing wells in the United States and millions more globally. Therefore, we evaluated methane screening measurements using a handheld device against direct emission rates, quantified using the static chamber method, at 200 wells in Alberta and Saskatchewan, Canada, and compared screening capabilities of two sensors at different price points in a controlled release setting. Screening was conducted using a portable methane detector that satisfies key elements of the United States (U.S.) Environmental Protection Agency Method 21. We found screening concentrations and emission rates were strongly correlated in Alberta and weakly correlated in Saskatchewan. Using a 10 part per million (ppm) threshold, screening reliably detected medium (1000–10 000 mg h −1 ) and high (>10 000 mg h −1 ) emitters with a 92% and 100% success rates, respectively. However, low emitters (<1000 mg h −1 ) were often missed, with only 24% detected at this threshold. Average daily wind speed showed limited influence on screening measurements at the 1% and 5% significance level, while maximum wind gust showed no effect on screening measurements. Both the higher-cost infrared absorption sensor and the lower-cost semiconductor metal oxide sensor effectively detected methane with screening concentrations above 10 ppm across flow rates ranging from 250 to 3000 mg h −1 . Our findings indicate that handheld screening tools can serve as an effective screening approach to flagging high-emitting wells, which can be useful in environmental risk characterization and well plugging prioritization frameworks for state regulators and other stakeholders.